From owner-qrp-l@Lehigh.EDU Sun Jun 2 14:57:17 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id OAA15914 for ; Sun, 2 Jun 1996 14:57:16 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id OAA15914 for ; Sun, 2 Jun 1996 14:57:16 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174376-51368>; Sun, 2 Jun 1996 14:56:27 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174166-51368>; Sun, 2 Jun 1996 14:55:34 -0400 Received: from mail.crl.com (mail.crl.com [165.113.1.22]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id OAA84817 for ; Sun, 2 Jun 1996 14:55:24 -0400 Received: from crl11.crl.com by mail.crl.com with SMTP id AA04457 (5.65c/IDA-1.5 for ); Sun, 2 Jun 1996 11:55:06 -0700 Received: by crl11.crl.com id AA20830 (5.65c/IDA-1.5); Sun, 2 Jun 1996 11:41:16 -0700 Message-Id: Date: Sun, 2 Jun 1996 11:41:15 -0700 (PDT) Reply-To: microres@crl.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Stanley Wilson To: "Low Power Amateur Radio Discussion" Subject: Re: Delta Loop Info Needed. In-Reply-To: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: Nancy-KL7NY/Jim-AL7FS/Juliann-WL7MP X-Cc: Low Power Amateur Radio Discussion X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Total length = 984/freq Each side = total length/3 b = side length/2 angle at each corner = 60 degrees On Sun, 2 Jun 1996, Nancy-KL7NY/Jim-AL7FS/Juliann-WL7MP wrote: > Greetings from Alaska. > > I have the rope up in the tree. I have searched for my info on the > dimensions for a 40 meter Delta Loop antenna and cannot find them. Help, > Please? > > I need the total length and how far down the one side the feed point should be. > > /\ > / \ Total Length = ? > B / \ > / \ A = > / \ C B = > =====O \ C = > / \ D = > A / \ > /________________\ > D > > Any pointers on the feedline or anything else? What if D is only 6 or 7 > feet off the ground? Am I wasting my efforts? I have the antenna > essentially built. I just need to pull it up in the tree and adjust to > final length. > > Thanks in advance. > > 73, > > > Jim Larsen > AL7FS > Anchorage, Alaska > > AL7FS TMPS 1996 Qs=003 States=02 Confirmed=00 DX=00 > CA OR > > > > From owner-qrp-l@Lehigh.EDU Sun Jun 2 21:11:47 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA04384 for ; Sun, 2 Jun 1996 21:11:46 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA04384 for ; Sun, 2 Jun 1996 21:11:46 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174691-51368>; Sun, 2 Jun 1996 21:10:43 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174184-48549>; Sun, 2 Jun 1996 21:09:56 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id VAA88243 for ; Sun, 2 Jun 1996 21:09:54 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id VAA11945; Sun, 2 Jun 1996 21:09:43 -0400 Message-Id: Date: Sun, 2 Jun 1996 21:09:42 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: 40 meter Delta loops MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO On received wisdom about 40 meter delta loops: Having read the recommendations for constructing a side-fed delta loop for 40 meters (center frequency 7.15 MHz), I went back into my modeling files and dug up some old info. Used NEC-2 over a high-accuracy ground. Built a model of a delta loop with the base 35' above ground and the peak 76.91' up. This is roughly 1038/f(MHz), with 1/3 on each of 3 sides and 60-degree angles. Modeled #14 copper wire. (Base and each side are 48.4' long). Side feeding: Input Z = 116 ohms, almost resonant (-j10 ohms) Gain is broadside to loop, slightly displaced toward the fed side. Max gain = 1.9 dBi at an angle of maximum radiation of 19 degrees. Pattern is very oval--almost circular on the fed side, flattened on the unfed side (about an 8 dB reduction from the main lobe). Bottom (center of bottom wire) feeding: Input Z = 138 ohms resonant (; Sun, 2 Jun 1996 23:43:40 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id XAA11554 for ; Sun, 2 Jun 1996 23:43:40 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174528-51368>; Sun, 2 Jun 1996 23:43:14 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174515-48039>; Sun, 2 Jun 1996 23:42:40 -0400 Received: from ume.med.ucalgary.ca (ume.med.ucalgary.ca [136.159.164.2]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id XAA42161 for ; Sun, 2 Jun 1996 23:42:35 -0400 Received: from localhost by ume.med.ucalgary.ca (4.1/CPSC-BACS4.1) id AA04103; Sun, 2 Jun 96 21:47:44 MDT Message-Id: Date: Sun, 2 Jun 1996 21:47:43 -0600 (MDT) Reply-To: zabrodsk@med.ucalgary.ca Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Rick Zabrodski To: "Low Power Amateur Radio Discussion" Subject: Re: 40 meter Delta loops In-Reply-To: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: "L. B. Cebik" X-Cc: Low Power Amateur Radio Discussion X-Sender: zabrodsk@ume X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO I have modelled ( and built ) two forty meter delta loops over the past 10 years at two different locations. I would aggree with LB that horizantal polarizaation is the way to go UNLESS you WANT rejection from high angle signals. As a general multipurpose 40 meter antenna the horizantal polarization works best. A practical plus is that although a loop is somewhat mor "quiet" than a dipole, this is MOST noticeable when horizatantally polarized. The better S/N ratio will make if a better performer as the "gain" is essentially the same for low angles as LB states. My question for LB. I am about to convert my 40 meter loop, apex at 60 feet, to a "sloping" loop for 80. It will be a quad configuration or possibly 6 sides. High end at 60 feet. Low end around 15 feet. The low end to high end horizanatal distance will be about 50 feet as I need to "stretch" things so I can get 250 feet or so of wire up there. (yes, I know this is a bit short.....that is the point of my question) I will feed it with 450 balanced line and one of my link coupled tuners (Perhaps my just aquired Johnson Match box ;-) ) My modelling suggests that even a little short, it should act like a full sized loop with a little less gain. It should have some gain in the direction of the slope and the gain should increase with frequency. Does this make sense? HOPEFULLY, somebody will then be able to hear me this winter come 40 meter fox hunting season!!!!!!! Comments appreciated, modellers and builders alike! Dr. Rick Zabrodski BSc, MD, CCFP(E) MRO * VE6GK Clinical Assistant Professor * NorCal 519 ARCI 7650 GQRP 8329 Faculty of Medicine, Univ. of Calgary * "Power is no substitute for skill" From owner-qrp-l@Lehigh.EDU Mon Jun 3 09:05:29 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id JAA08870 for ; Mon, 3 Jun 1996 09:05:28 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id JAA08870 for ; Mon, 3 Jun 1996 09:05:28 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174673-34133>; Mon, 3 Jun 1996 09:00:24 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174666-34133>; Mon, 3 Jun 1996 08:59:19 -0400 Received: from conciliator.acsu.buffalo.edu (root@conciliator.acsu.buffalo.edu [128.205.7.20]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id IAA65242 for ; Mon, 3 Jun 1996 08:59:09 -0400 Received: from ubppp-015.ppp-net.buffalo.edu (ubppp-015.ppp-net.buffalo.edu [128.205.222.79]) by conciliator.acsu.buffalo.edu (8.7.4/8.7.3) with SMTP id IAA21992; Mon, 3 Jun 1996 08:59:00 -0400 (EDT) Message-Id: <31B30BA0.4C99@acsu.buffalo.edu> Date: Mon, 03 Jun 1996 08:58:24 -0700 Reply-To: msadams@acsu.buffalo.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Mark S. Adams" To: "Low Power Amateur Radio Discussion" Subject: Re: Delta Loop Info Needed. References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: Nancy-KL7NY/Jim-AL7FS/Juliann-WL7MP X-Cc: qrp-l@Lehigh.EDU X-Mailer: Mozilla 2.0 (Win16; I) X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Hi Jim and Gang, >Thanks for the info. Question. I have received two replies that suggest I >need to feed it 1/2 way up the side for vertical polarization. Yours is 5 >feet up. I believe that feeding a delta halfway up a side will yield horizontal polarization, not vertical. See Doug Demaw's article on "Delta Loops at Low Height" from the 10/84 QST. I would fax it to you but I do not have a fax machine in the home office. It, along with the delta loop info in OH2UN's? book, "Low Band DX'ing" will clear all these questions up quite well. In the DXing book John says to feed the loop about ____ lamda (I do not remember the exact value, nor do I own the book) up from a lower corner for best low angle radiation. When I had my antenna horizontally polarized with the feed at the apex I heard/worked NO dx. When I moved it to just above the lower corner I struck gold. Rich, VE6GK? suggest a better sig:noise ratio for the horizontal case hence better receive performance. This did not work for me in practice. Also, with a tilted loop the polaraziation is probably mixed so the number of variables is too many to account for. If you cannot decide, is it possible to construct the antenna so you can simply rotate the wire after taking tension off loop? You could check both cases and see for yourself. I could not do this easily because my chimney is in the way. I ran for 3 months feeding the apex and thereafter feeding abt 5' up from a lower corner. >Also, I am inferring from replies that the feed point is about 200 ohms >and a 4:1 balun would work for a 40 mtr monoband antenna. Do you agree? YUP! If I were monobanding it I would use a 4:1 and coax fer sure. >Later, I may want to try the 450 ohm feedline. Trouble is I have never >used it and would have to find out where to buy it, how to run it into the >house, how to tune it, etc. Coax would be best for right now. Comments? I had the same trouble. I finally just bought some from the Wireman (ad in QST). I had some ceramic insulators with spikes that I hammered into the side of the house at 10' intervals as needed (the XYL asked many questions during installation) and ran into my basement shack thru a tiny vent window in the glass block that I replaced with a plexiglass panel. The panel has a slot for the twinlead and a bulkhead connector for coax. -- 72's de Mark/N2VPK TMPS 1996 Q's=41 States=19 Confirmed=00 DX=05 AL CA CO CT IN FL KY MA MI MD ME NC NY PA SC SD TN TX WI CT3 VE1 6W1 OZ7 HC1 From owner-qrp-l@Lehigh.EDU Mon Jun 3 15:11:52 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id PAA03512 for ; Mon, 3 Jun 1996 15:11:49 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id PAA03512 for ; Mon, 3 Jun 1996 15:11:49 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174465-43092>; Mon, 3 Jun 1996 14:50:03 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174295-25170>; Mon, 3 Jun 1996 14:47:35 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id OAA136982 for ; Mon, 3 Jun 1996 14:47:14 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id OAA25796; Mon, 3 Jun 1996 14:46:57 -0400 Message-Id: Date: Mon, 3 Jun 1996 14:46:56 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Delta loops (long, erase now if not interested) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO More notes on the delta loop Several folks raised some further questions about the delta loop. so I ran a more complete series of models, including some at lower heights and with varying feedpoints. Although I cannot put patterns on the net, here is a summary of the results. All antennas are #12 copper wire, total length 1038/f (42.8'/side at 7.15 MHz) over medium earth (via Somerfeld-Norton ground calculations). All initial models are 35' above ground at bottom and 76.91' at the top. All gain figures in dBi, dimensions in feet, and impedances in Ohms. 1. You can run a delta with the horizontal low or high. If you run it high, you will get better gain (more wire higher) and lower angles of maximum radiation (TO angles) than with the horizontal wire low, about 1.3 dB more, and about 9 degrees lower. 2. If you feed the side, a point about 25 percent up the leg from the bottom provides the lowest TO angle (15 degrees), the maximum vertical component to the wave polarization, but the lowest max. gain (1.4 dBi). By way of contrast, here is a chart of deltas and their radiation at 15 degrees: Type Feedpoint Gain Z Hor low Middle of bottom 2.28 138 - j1.4 Hor low Low corner 1.85 121 - j18 Hor low 25% up 1.39 110 - j15 Hor low Mid-side 1.91 116 - j11 Hor low Top peak 2.15 140 - j11 Hor high Middle of top 5.38 115 - j15 Hor high Bottom apex 5.24 117 - j23 Hor high Mid-side 2.97 111 - j11 Hor high 25% up side 1.17 108 - j11 As you can see, low angle radiation favors the centered horizontal feedpoint, whether top or bottom, whether the delta is point up or point down. Point down is the superior performer, as shown by this little chart: Type Feedpoint Gain TO Angle Z Hor high Middle of top 7.50 28 deg 115 - j15 Hor high Bottom apex 7.34 28 117 - j23 Hor low Top apex 5.88 37 140 - j11 Hor low Middle of bottom 6.01 37 138 - j1.4 Of course, bottom apex feeding of the hor high, apex low version may be the most convenient, and the .16 dB reduction below max gain is insignificant. 3. As you lower the bottom of the antenna, the TO angle increases, so that the bottom low middle of bottom wire fed version loses its advantage over the corner, 25% up, and 50%up the side fed versions. However, the Hor high, fed top or bottom version retains its advantage over the corner or side-fed versions. Type Heights (') Gain TO angle Z Hor high 35 bot, 76.91 top 7.34 28 deg 117 - j23 Same at TO = 15 deg 5.24 Hor high 20 bot, 61.91 top 6.28 35 135 - j17 Same at TO = 15 deg 2.91 Hor high 5 bot, 46.91 top 5.50 46 131 + j5 Same at TO = 15 deg 0.48 Hor low 35 bot, 76.91 top 6.01 37 138 - j1.4 Same at TO = 15 deg 2.28 Hor low 20 bot, 61.91 top 5.13 51 124 + j26 Same at TO = 15 deg -0.24 Hor low 5 bot, 46.91 top 1.91 72 107 + j43 Same at TO = 15 deg -4.96 The losses of radiation to ground increase rapidly as the horizontal at the bottom version of the delta loop gets lower. Where the horizontal is at the top of the antenna, the gain is initially higher, the angle is lower, and the gain decreases more slowly as the antenna approaches the earth. Until the apex of this version gets well under 20', it is still likely to outperform a corner/side-fed version, even at the lower angle needed for dx. (And, some studies suggest that at lower frequencies, the angle necessary for a path is higher than it is for higher frequencies--all within limits, of course, that is within the 8 to 20 degree range.) 4. Polarization: with any loop antenna used at HF for other than point-to- point communications (miscalled "line-of-sight"), polarization is of no concern. A loop has both kinds, because current is flowing in al the wires, the orientation of which determines field generation. The reason there is no magic to polarization is that the ionosphere scrambles it before it starts down. However, the side-fed models have lower angles of max radiation because of the greater proportion of vertically polarized radiation. Nonetheless, their total fields remain weaker due to some field/current cancellation. The key measures are a combination of total field and the TO angle of interest. The latter is often the angle of max radiation in the absence of other considerations, but if you have a path you are concerned about, then that angle is of concern. I have chosen 15 degrees for 2 reasons: it is the lowest angle of max radiation for the side-fed models and it is a good dx angle on 40 meters. The greater gain at higher angles of the top and bottom fed models is not lost, but will of greater benefit for domestic or short-hop QSOs. 5. Feeding the loop: With minor length adjustments (and remember that models will not tell us what your house and trees are doing to the antenna pattern of feedpoint impedance), any of the models can be brought to resonance and fed with a balun of the proper ratio and coax. Remember to cancel the reactance on the antenna side of the balun, since (as balun guru Jerry Sevick notes) transmission line transformers work best with resistive loads. However, as I see it (which may differ from how others see it), there is little point in putting that much wire in the air without trying it on a lot of bands. And that means parallel transmission line and an ATU. Losses in the line will be insignificant, even with the added ATU loss, and 450-ohm line should work very well with an easy match at 40 for almost any length on any ATU. If you can find good Belden (or equiv.) 300-Ohm line, use it, but avoid the TV cheapy stuff and the shielded parallel line. Rick (VE6GK, of FDIM lunch fame) asks about a 250-foot loop, sloping, multi- sided, 15' high at the bottom and 60' high at the top, fed with 450-ohm line and used on 80, 40, etc. That ought to work quite well, especially if you cannot get a full length 80-meter dipole up to the 60' level (which, from the photos I saw ought to put the second tower in the neighbor's yard). Models suggest performance at least as good as a 60' high dipole--better for some models, a tad worse for others, but I did not have the exact layout. If a Johnson matchbox cannot match this system, sell it to me for $5, since it obviously defective. Rick's situation is indicative of many others: one real high point, limited linear space. Make a loop as long as possible, get it as high as possible at as many points as possible, and try to keep the low point at least at roof-top level or better. The farther away from ground you place every point along the loop, the better it is likely (but not absolutely guaranteed) to work. Hope this exercise helps enough of the loopers and potential loopers on the net to justify the length of this note. To the non-loopers, my apologies. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Mon Jun 3 17:36:52 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id RAA14077 for ; Mon, 3 Jun 1996 17:36:50 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id RAA14077 for ; Mon, 3 Jun 1996 17:36:50 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174705-43092>; Mon, 3 Jun 1996 17:34:46 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174412-34133>; Mon, 3 Jun 1996 17:30:55 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id RAA54018 for ; Mon, 3 Jun 1996 17:30:28 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id RAA16982; Mon, 3 Jun 1996 17:30:10 -0400 Message-Id: Date: Mon, 3 Jun 1996 17:30:09 -0400 (EDT) Reply-To: wynnt@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: NONE To: "Low Power Amateur Radio Discussion" Subject: Re: Delta loops (long, erase no MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: wynnt@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO L. B., almost a very nice paper on deltas, but you left out two important items from the parametric mix. Please submit again with permutations and consideration for: 1. the tilt of the plane of the delta out of the vertical plane for 10, 20, and 30 degrees for both the horizontal low and horizontal high; 2. rotation of the plane of the delta within the vertical plane with horizontal vertical and vertical (apex) horizontal. Both these parameters will be useful to those constructors who can't arrive at the perfect equalateral triangle in a plumb condition. -wynnt From owner-qrp-l@Lehigh.EDU Mon Jun 3 21:53:05 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA27016 for ; Mon, 3 Jun 1996 21:53:04 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA27016 for ; Mon, 3 Jun 1996 21:53:04 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174780-25170>; Mon, 3 Jun 1996 21:52:38 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174771-25170>; Mon, 3 Jun 1996 21:51:43 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id VAA96321 for ; Mon, 3 Jun 1996 21:51:31 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id VAA02648; Mon, 3 Jun 1996 21:50:56 -0400 Message-Id: Date: Mon, 3 Jun 1996 21:50:55 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Re: Delta loops In-Reply-To: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: NONE X-Cc: Low Power Amateur Radio Discussion X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO On Mon, 3 Jun 1996, NONE wrote: > almost a very nice paper on deltas, but you left out two important > items from the parametric mix. Please submit again with permutations > and consideration for: Thank you, but no, thank you. W4RNL From owner-qrp-l@Lehigh.EDU Tue Jun 4 08:21:13 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id IAA28470 for ; Tue, 4 Jun 1996 08:21:11 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id IAA28470 for ; Tue, 4 Jun 1996 08:21:11 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174180-28903>; Tue, 4 Jun 1996 08:20:36 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174153-28903>; Tue, 4 Jun 1996 08:19:55 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id IAA114171 for ; Tue, 4 Jun 1996 08:19:51 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id IAA23593; Tue, 4 Jun 1996 08:19:17 -0400 Message-Id: Date: Tue, 4 Jun 1996 08:19:14 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Re: Delta Loops In-Reply-To: <199606040444.VAA02256@key.cyberg8t.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: Cam Hartford X-Cc: qrp-l@Lehigh.EDU X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO On Mon, 3 Jun 1996, Cam Hartford wrote: > In ON4UN's book, "Low Band DXing" there is an interesting discussion of the > delta loop. He suggests that if the loop is fed at a point which is a > quarter wave down one side from the top, it acts as two verticals with the > bottom essentially a radial. This gives the lowest possible angle of > radiation from a delta, which in some circumstances would make it more > useful than a center-bottom fed loop. Cam, Good question. ON4UN's book is a classic with many excellent presentations and ideas for the "low" band operator. Unfortunately, he did not have access to contemporary antenna modeling techniques that provide a check on the kind of mental pictures we often use to develop explanations. And in this case, the author goes a bit astray. For the "apex on top, horizontal wire on the bottom" version of the delta loop, the lowest angle of maximum radiation occurs when fed about 25% up from the bottom. This point coincides with the weakest total radiation field (predominantly vertically polarized) (<1.4 dBi at 15 degrees up) due to interactive cancellations of currents in the wires, especially in the upper regions of the antenna. THis can be seen by examining a chart of the wire currents and watching their phase angles: there are areas in which the "vertical" wires have comparable currents but opposing phase angles in near proximity--a good condition for a partial cancellation of fields. Feeding the wire at the 3/4 up point--or your 25% down point yields a modification of the top-apex fed version, with a reduction of gain to 4.6 dBi (from the max near 6 dBi) at 36 degrees as the angle of maximum radiation. The currents do not distribute themselves in mutually reinforcing ways, but simply progress along the full-wave loop with max at the feedpoint and a secondary max approximately a half-wavelength of wire around the loop. Current minima are approximately 1/4 wavelength from maxima, which places them at geometrically odd points for uncentered feed points, like either the 25% up or the 25% down locations. (I add the term "approximate" since mutual interaction over the antenna's geometry, plus ground reflections, complicate matters--and these complications are clearly visible in a chart of currents along the antenna wire.) Best delta loop performance occurs with the apex down, fed either at top (inconvenient) center or at the bottom apex. The antenna is best suited to situations where a full-length dipole cannot be placed at the height of the top wire of the delta. The full-length dipole at that height will provide roughly equal performance as the loop, but with half as much wire (but all of it "way up"). A quad loop will perform similarly, with its top wite at the same height as the delta loop top wire (which will raise the bottom wire, since the quad is 1/4 wl on a side). The Quad loop fits where only 1/4 wl linear space is available. In general (rule-of-thumb time) a quad or delta loop will provide about 1.8 dB additional gain over a dipole whose height is about centered in the loops vertical plane. Raise the dipole to the top of the loop, and the difference disappears, but at the expense of a longer antenna. Hence, first, think as HIGH as you can possible erect and maintain. Second, think loop when linear available linear space is less than 1/2 wl, but vertical space is available. BUT, do not throw away your copy of ON4UN's book--there is too much of value in it on a whole lot of subjects. Hope this is useful (and hence, distributing to QRP-L). -73- LB, W4RNL From owner-qrp-l@lehigh.edu Tue Jun 4 09:17:42 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id JAA00986 for ; Tue, 4 Jun 1996 09:17:41 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id JAA00986 for ; Tue, 4 Jun 1996 09:17:41 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174516-44772>; Tue, 4 Jun 1996 09:06:09 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174507-28903>; Tue, 4 Jun 1996 09:04:56 -0400 Received: from destrier.acsu.buffalo.edu (root@destrier.acsu.buffalo.edu [128.205.7.21]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id JAA125232 for ; Tue, 4 Jun 1996 09:04:38 -0400 Received: from ubppp-004.ppp-net.buffalo.edu (ubppp-004.ppp-net.buffalo.edu [128.205.222.68]) by destrier.acsu.buffalo.edu (8.7.4/8.7.3) with SMTP id JAA20916; Tue, 4 Jun 1996 09:04:24 -0400 (EDT) Message-Id: <31B45E6D.2052@acsu.buffalo.edu> Date: Tue, 04 Jun 1996 09:03:57 -0700 Reply-To: msadams@acsu.buffalo.edu Sender: owner-qrp-l@lehigh.edu Precedence: bulk From: "Mark S. Adams" To: "Low Power Amateur Radio Discussion" Subject: Re: Delta Loops References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: cebik@utkux.utcc.utk.edu X-Cc: Low Power Amateur Radio Discussion X-Mailer: Mozilla 2.0 (Win16; I) X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Hi L.B. and Gang, LB- The delta loop questions are sure difficult as this antenna seems to be somewhat difficult to model and first hand experience seems to counter the computer analysis. I have a delta in the air now. Its been up for over a year. Its configuration is as follows: * apex up at 35' * horizontal wire at 10' * cut to 142' length * fed with 450 ohm line at abt 5' up from a lower corner. I initially installed it with the feed at the apex. Worked ZERO DX in abt 3 months. After the feed change the DX was plentiful and the close in contacts were hard to come by. This seems contrary to the computer modeling. My antenna also seems to pull in 4-land like gangbusters. I suppose that is because I have an E-W gutter that is abt 8' from the loop helping it to radiate towards the south from here in WNY. So LB, do you think that I would be better off with a dipole all at 35' fed with laddder line instead of the loop with the lower avg height? I have struggled with this question for a while but I hate to climb on the roof and make changes when the loop works well. An option that I do not have is hanging the loop vertically. Part of the house is in the way. I read in an old QST article on diamond loops (this fella had a delta up first) that the delta had a much more variable signal. The diamond was far better for him. Again this is with one high support. Well, at any rate, even superb and undeniably excellent advice will not get acted upon here until my broken pelvis heals! See you on 30M! -- 72's de Mark/N2VPK TMPS 1996 Q's=43 WAS=19 Confirmed=00 DX=05 AL CA CO CT IN FL KY MA MI MD ME NC NY PA SC SD TN TX WI CT3 VE1 6W1 OZ7 HC1 From owner-qrp-l@lehigh.edu Tue Jun 4 13:15:44 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id NAA18485 for ; Tue, 4 Jun 1996 13:15:38 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id NAA18485 for ; Tue, 4 Jun 1996 13:15:38 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174709-44772>; Tue, 4 Jun 1996 12:45:06 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174696-28903>; Tue, 4 Jun 1996 12:44:10 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id MAA134710 for ; Tue, 4 Jun 1996 12:44:02 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id MAA29001; Tue, 4 Jun 1996 12:43:33 -0400 Message-Id: Date: Tue, 4 Jun 1996 12:43:32 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@lehigh.edu Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Re: Delta Loops In-Reply-To: <31B45E6D.2052@acsu.buffalo.edu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: "Mark S. Adams" X-Cc: Low Power Amateur Radio Discussion X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Mark, Do not change anything (unless you just want to, that is). If you will notice on one of my previous posts, when the bottom horizontal wire is very close to the ground (my model used 5', but 10' ain't significantly better), the gain of the antenna drops radically at all angles of radiation. It is under these conditions that side or corner feed may be superior. The gain at a 5' bottom wire height with bottom or top center feed drops to almost -5 dBi, with max gain at a whoppingly high angle of 72 degrees. The side-corner fed model tends to hold its gain at about 1.4 or so as the antenna is lowered from the more optimal heights used for some of the other models. 35' is only about a quarter-wavelength up--not a real good height for dipoles, Yagis, or other planar horizontal antennas (on 7 MHz band). If that is all one can do, then one should do it. But for horizontals, something around a half wavelength up and higher improves low angle performance tremendously. 35' becomes a sort of bare minimum for fair to good performance of horizontal antennas on 20 meters and up. (Yes, they will perform lower, but I am speaking in comparative terms here.) That is why verticals are often used on 160-40 meters. The GAP works well, but is very tall. Quarter wave verticals trapped for 40-10 meters (Butternut, Hy-Gain, etc.) tend to do better on roof tops with drooping radials (more than the instruction sheet minimum). That is because the drooping radials act as much like the other half of a vertical dipole as they act like a ground plane in this configuration. (I have used a 14AVQ for several years with great success from a roof top, and now have a GAP VI going on its 6th year of uninterrupted service.) Because so much of an actual installation depends upon surround objects, it is difficult to say which might be better--the elevated or half-wavelength vertical or the side-fed delta when the bottom wire is very low. Getting half a dozen folks to invest in both and put eahc one up very carefully for side-by-side tests would be asking more than folks can do. Wire loops are cheap; roof-top verticals are compact--more than theoretical performance will go into the final decision. But never argue with success. Except for periodic maintenance, never take down an antenna that is performing well. But if you get the chance to add an antenna for comparative performance checks, then by all means try it out. (But only after you are mended!) And I would not change the feedpoint of the delta unless you get a change to elevate it so the bottom wire is up 25' or more. Hope this clarifies the earlier notes, most of which are based on more highly elevated antennas than your installation. Get well soon. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Tue Jun 4 13:39:24 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id NAA20046 for ; Tue, 4 Jun 1996 13:39:21 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id NAA20046 for ; Tue, 4 Jun 1996 13:39:21 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174845-28903>; Tue, 4 Jun 1996 13:28:22 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174819-44772>; Tue, 4 Jun 1996 13:25:04 -0400 Received: from dt1.datatamers.com (root@dt1.datatamers.com [140.174.237.1]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id NAA92653 for ; Tue, 4 Jun 1996 13:24:27 -0400 Message-Id: Date: Tue, 4 Jun 1996 10:14:41 -0700 (PDT) Reply-To: ddm@datatamers.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "David D. Meacham" To: "Low Power Amateur Radio Discussion" Subject: Re: Delta Loops In-Reply-To: <31B45E6D.2052@acsu.buffalo.edu> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: "Mark S. Adams" X-Cc: Low Power Amateur Radio Discussion X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Mark, I have had the same results that you have had! My apex is at 37 ft, bottom wire at 7 ft, fed 1/4-wave down from apex with 72-Ohm transmitting twinlead, from a Johnson-Matchbox tuner. Antenna no good until about 500 miles out. Really plays beyond 900 miles out. Easily covers the whole 40m band. I love it for DX! 72, Dave, W6EMD From owner-qrp-l@Lehigh.EDU Wed Jun 5 11:30:07 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA29773 for ; Wed, 5 Jun 1996 11:30:06 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA29773 for ; Wed, 5 Jun 1996 11:30:06 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174663-50218>; Wed, 5 Jun 1996 11:28:20 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174672-50218>; Wed, 5 Jun 1996 11:25:47 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id LAA21304 for ; Wed, 5 Jun 1996 11:25:35 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id LAA10094; Wed, 5 Jun 1996 11:25:02 -0400 Message-Id: Date: Wed, 5 Jun 1996 11:25:01 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Deltas at lower heights (long, erase if uninterested) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Low-Down Deltas: More than one person has noted that my initial findings on the delta loop were based on well-elevated models, but that most (though not all) ham 40-meter deltas would likely be close to the ground at one point or more. This is a good observation. Initial models were made free and clear to form a baseline for knowing when data might become unreliable as we press models closer to the ground. Even NEC's Somerfeld-Norton ground calculation system is not perfect. The closer to the ground, the more uncertain models become. There is no way to know what your particular delta loop might be strung around or amid: trees, shrubs, house wiring, children's play sets, etc. So with the understanding that a. the closer to ground, the less reliable models become and b. the more the antenna will be influenced by things I cannot model, we can look at low down deltas. For now, we shall keep them upright (in a vertical plane). Like all the models, the antennas are made to the same circumference (1050/f (MHz)) of #12 copper wire over medium earth. We shall compare 4 versions: BOT = horizontal wire at the bottom, fed in the middle of the horizontal wire; APX = horizontal wire at the top, fed at the apex at the bottom; D25 = horizontal wire at the bottom, fed 25% up one side; and V25 = horizontal wire at top, fed 25% down one side. The reason for the choice of 25% up or down, is that this point yields the lowest angle of maximum radiation for the side-fed models. It is hard to print a complete chart across a single screen, so we shall pair up the antennas and look at the progressions of gain (GN) in dBi, angle of maximum radiation (TO), and feedpoint impedance (Z) in ohms at a series of heights. The heights will be for the lowest part of the antenna--the uppermost part will be about 40' or so higher. BOT APX GN TO Z Height GN TO Z 6.01 37 138 - j1.5 35 7.34 28 117 - j23 5.71 41 137 + j8 30 7.00 30 123 - j24 5.43 45 132 + j18 25 6.64 32 129 - j22 5.13 51 124 + j25 20 6.29 35 135 - j17 4.67 57 114 + j30 15 5.99 38 137 - j10 3.80 64 105 + j32 10 5.73 42 136 - 1.6 1.90 72 107 + j42 5 5.50 46 131 + 5.4 D25 V25 1.39 15 110 - j15 35 1.17 14 108 - j11 1.44 16 114 - j20 30 1.20 15 110 - j15 1.44 17 120 - j23 25 1.21 15 113 - j19 1.39 18 130 - j24 20 1.17 16 120 - j23 1.28 20 143 - j21 15 1.08 17 130 - j24 1.12 21 162 - j8.1 10 0.93 18 144 - j21 0.84 23 191 + j28 5 0.72 20 166 - j6.7 So what does the data from the models mean. Here is a random list of potential conclusions: 1. There is no performance difference between the two side-fed models. Differences in gain under 0.2 dB are insignificant, and the figures grow more tentative as the base-height approaches ground level. As noted in an earlier message in this series (which did not begin with the intention of being a series), the side-fed antennas maintain their performance over a range of base-heights. High-angle radiation (and reception potential, of course) are much reduced in both side-fed versions. Moving the feedpoint more than about +/-10% increases the high-angle radiation very quickly with increasing gain very fast (until you reach the 60% mark along the vertical wire), thus defeating the purpose of side feed. 2. At all base-heights, APX (horizontal wire at the top, fed at the apex at the bottom) provides superior performance to BOT (horizontal wire at the bottom, with the feedpoint in the center of that wire). Gain is higher (due to the horizontal wire being always higher), and the angle of max radiation is always lower. 3. The gain of APX at an angle of 15 degrees (comparable to the D25 and V25 angles of maximum radiation) has this short pattern: Height = 5' Gain at 15 degrees = 0.48 dBi 10' 1.30 15' 2.11 Note that by a base-height of 15', the gain at "dx" angles exceeds that of either side-fed model. However, the angle of max radiation is much higher, meaning that the antenna will respond to shorter skip comparatively strongly. For some this means more QSO possibilities, for others it means QRM on the dx contact. With the APX bottom apex at 15' up, the top horizontal wire would be higher than 55'. If you can get that wire up that high (or higher), the APX version may be the way to go. If you can't, then perhaps (assuming you just gotta have a delta loop), one of the side-feed models will fill the bill. 4. Although ON4UN's explanations of delta beam operation lack theoretical foundations, his conclusions are sound when the bottom wire has to be very close to the ground: the side-feed can out-perform the bottom feed for dx. The delta beam does not need a counterpoise or ground system. Since ground- mounted vertical losses are high in most ham installations, due to the use of short, low-Z verticals and relatively ineffective ground systems, the side-fed delta loop may outperform many of them for dx. However, it is unclear whether the side-fed delta loop, with its gain of less than 1.5 dBi can be expected (from modeling data) to consistently out-perform loaded half-wave vertical dipoles or roof-top quarterwave verticals (usually with traps) with at least 4 radials per band. The responses to earlier modeling notes on the delta loop have been extensive, but of course, only a minority of the net members are interested. But perhaps every individual subject serves only a minority of the 1K members of the net. I can only ask the indulgence of those whose interests lie elsewhere on behalf of those who use or are contemplating building a delta. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Wed Jun 5 12:23:45 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id MAA03861 for ; Wed, 5 Jun 1996 12:23:44 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id MAA03861 for ; Wed, 5 Jun 1996 12:23:44 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175284-50218>; Wed, 5 Jun 1996 12:16:34 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175202-50218>; Wed, 5 Jun 1996 12:14:20 -0400 Received: from conciliator.acsu.buffalo.edu (root@conciliator.acsu.buffalo.edu [128.205.7.20]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id MAA96341 for ; Wed, 5 Jun 1996 12:13:50 -0400 Received: from ubppp-021.ppp-net.buffalo.edu (ubppp-021.ppp-net.buffalo.edu [128.205.222.85]) by conciliator.acsu.buffalo.edu (8.7.4/8.7.3) with SMTP id MAA23984; Wed, 5 Jun 1996 12:13:39 -0400 (EDT) Message-Id: <31B5DC42.124@acsu.buffalo.edu> Date: Wed, 05 Jun 1996 12:13:06 -0700 Reply-To: msadams@acsu.buffalo.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Mark S. Adams" To: "Low Power Amateur Radio Discussion" Subject: Re: Deltas at lower heights (long, erase if uninterested) References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: cebik@utkux.utcc.utk.edu X-Cc: Low Power Amateur Radio Discussion X-Mailer: Mozilla 2.0 (Win16; I) X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Great work LB, and hello to the gang, I think that the low height deltas should be of great interest to most of us, especially the guys who like /P operations. This antenna is a good one to consider as it requires only one high support and can be tilted if necessary to conserve the vertical height you do not have all of the time. It gets a full wave lenght of with up for the lowest band you are working and can be fed with ladder line to work a bunch of bands! Now if you only have just so many nice trees and want a bunch of good single band antennas this could be your ticket. Consider the low height delta. And read the W1FB article in QST, 10/84? -- 72's de Mark, aka N2VPK TMPS 1996 Q's=52 WAS=19 Confirmed=00 DX=08 AL CA CO CT IN FL KY MA MI MD ME NC NY PA SC SD TN TX WI WY CT3 EA ES HC LY OZ VE1 6W1 From owner-qrp-l@Lehigh.EDU Wed Jun 5 14:17:14 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id OAA09678 for ; Wed, 5 Jun 1996 14:17:11 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id OAA09678 for ; Wed, 5 Jun 1996 14:17:11 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175569-50218>; Wed, 5 Jun 1996 13:57:27 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175241-24107>; Wed, 5 Jun 1996 13:55:23 -0400 Received: from mail13.digital.com (mail13.digital.com [192.208.46.30]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id NAA46411 for ; Wed, 5 Jun 1996 13:55:13 -0400 Received: from us1rmc.bb.dec.com by mail13.digital.com (8.7.5/UNX 1.2/1.0/WV) id NAA17331; Wed, 5 Jun 1996 13:45:12 -0400 (EDT) Received: from asdg.enet by us1rmc.bb.dec.com (5.65/rmc-22feb94) id AA05262; Wed, 5 Jun 96 13:45:18 -0400 Received: from asdg.enet; by us1rmc.enet; Wed, 5 Jun 96 13:45:18 EDT Message-Id: <9606051745.AA05262@us1rmc.bb.dec.com> Date: Wed, 5 Jun 96 13:45:18 EDT Reply-To: acito@asdg.ENET.dec.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Bill Acito 05-Jun-1996 1348 To: "Low Power Amateur Radio Discussion" Subject: Re: Deltas at lower heights (long, erase if uninterested) X-To: -qrp@us1RMC.bb.dec.com X-Cc: acito@asdg.ENET.dec.com X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO I agree with Mark.... keep it coming LB. b 40m Band Captain for W1FMR QRP-NE Field Day (who's planning a delta loop beam for Field Day). . . . . . . - I own my own words - . . . . . . Bill Acito acito@asdg.enet.dec.com |d|i|g|i|t|a|l| Digital Equipment Corporation Hudson, MA KC1GS qrp-ne qrp-l arci norcal amsat-na arrl-life From owner-qrp-l@Lehigh.EDU Wed Jun 5 20:54:01 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id UAA03231 for ; Wed, 5 Jun 1996 20:53:58 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id UAA03231 for ; Wed, 5 Jun 1996 20:53:58 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174153-51496>; Wed, 5 Jun 1996 20:52:33 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174153-50218>; Wed, 5 Jun 1996 20:51:49 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id UAA107156 for ; Wed, 5 Jun 1996 20:51:42 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id UAA19803; Wed, 5 Jun 1996 20:51:06 -0400 Message-Id: Date: Wed, 5 Jun 1996 20:51:06 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Tilt! (deltas again--you know the erase routine) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Deltas tilted and flat Hate to keep this up, but I have also been asked by a couple of folks what happens if I lay out a delta loop horizontally or tilted. I suspect that a tall tree or tower in the yard makes this a tempting layout. So I took my trusty #12 copper delta loop 1050/f (MHz) long total over medium S-N ground on a NEC-2 journey through tilt-over. Actually, I took two models: BOT with the horizontal wire down and fed in the middle of the lower wire, and APX with the horizontal wire up and fed at the lower apex. Here is what happened (with the usual cautions about being unable to account for yard clutter, etc.). All gain figures are broadside to the face of the loop or, when horizontal, along the axis from the apex through the middle of the top/bottom wire. BOT: I laid this model over to horizontal at both 35' (a typical height) and at 75' (a convenient tall height about where the peak of the upright delta was in the earliest models). I not only recorded the max gain, but also the gain at 15 degrees, the approximate optimal angle of max radiation for the side-fed models. Height Max Gain TO angle Z Gain at 15-deg angle Upright 6.01 37 138 - j1.5 2.28 35' 6.23 81 144 + j23 -1.80 75' 7.16 26 97 - j11 5.30 APX: The model fed at the apex (down) with the horizontal wire up can also be laid out horizontally. Height Max Gain TO angle Z Gain at 15-deg angle Upright 7.34 28 117 - j23 5.24 35' 6.05 85 151 + j14 -2.09 75' 6.91 26 99 - j16 5.05 In fact, there are no significant differences between these two models, which differ essentially only in whether they are fed at an apex or at a wire center. However, notice the height necessary to produce significant low angle radiation. 75' is just a little more than a half-wavelength at 7.15 MHz. I then tilted each antenna at a 45 degree angle to earth and modeled it with a base height of 35' and again at 10' off the ground. The top heights were 65' and 40' respectively. Here's what I got: BOT (feedpoint center of wire, which is at lowest point): Height Max Gain TO angle Z Gain at 15-deg angle 35' 5.89 46 144 + j2.3 0.76 10' 4.52 79 102 + j42 -4.12 APX (feedpoint at apex, which is at lowest point): Height Max Gain TO angle Z Gain at 15-deg angle 35' 6.35 34 131 - j29 3.11 10' 5.79 62 134 + j18 -0.78 Note that the tilted APX outperforms the tilted BOT, which is consistent with the previously reported model performance of the upright deltas. In both cases, performance is somewhere between the vertical and horizontal performance. The lower the antenna bottom, the higher the angle of maximum radiation and the less radiation at low dx angles. And what applies to transmitted radiation angles applies equally to reception angles. You can interpolate reasonable numbers for angles other than 45 degrees. Whether the performance is good or bad depends upon your standard of comparison. Remember that receivers for 40 meters have excess gain. So a low gain antenna is does not mean no contacts. The noise goes down with the gain, so the signal to noise ration remains relatively constant. Now, if the pattern is narrowed so that the antenna does not pick up noise from every possible direction in the hemisphere around it, then the signal to noise ratio is improved. One factor, previously unnoted, about the 25% up-the-side-fed deltas is the relative flatness of their patterns, with decreased noise pickup from higher vertical angles. That may contribute to their utility as weak signal antennas, if the operator increases the receiver gain. (Internal receiver noise will never be a problem on 40 meters as it can be on 10.) But the question remains, what is an appropriate standard against which to judge a delta loop? A low dipole? A high dipole? A ground-mounted vertical? A rook-mounted vertical? A loaded vertical dipole? Hmmm, back to the software. . . -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Thu Jun 6 08:03:53 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id IAA03299 for ; Thu, 6 Jun 1996 08:03:50 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id IAA03299 for ; Thu, 6 Jun 1996 08:03:50 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175777-50189>; Thu, 6 Jun 1996 08:03:12 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174403-50189>; Thu, 6 Jun 1996 08:02:41 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id IAA135880 for ; Thu, 6 Jun 1996 08:02:37 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id IAA15621; Thu, 6 Jun 1996 08:01:58 -0400 Message-Id: Date: Thu, 6 Jun 1996 08:01:57 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: deltas on other bands (long, erase, etc.) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO The 40-meter delta loop on other bands We have been looking at 40-meter delta loop models. The results can be scaled with caution for other bands. However, I have been asked whether the delta loop can be used effectively on other bands. It seems plausible, but let's see what is really likely to happen. I modeled three antennas: BOT (horizontal wire at bottom and bottom fed in the center of that wire); APX (horizontal wire at top, with feed at the apex at the bottom); and D25 (horizontal wire at bottom, fed 25% up on sloping side). I ran these #12 copper wire 1050/f (MHz) long antennas about 10' above over S-N medium ground at their lowest points to simulate what seems to be the average ham installation, and I ran models at 3.55, 7.15, 10.1, and 14.15 MHz. Here is what the models returned: BOT: Freq (MHz) Gain(dBi) TO angle (deg) Z (R+/-jX-Ohms) 3.55 2.16 90 8145 - j20310 7.15 3.80 64 105 + j32 10.10 4.94 36 1262 + j3831 14.15 5.48 88 368 + j83 APX: Freq (MHz) Gain(dBi) TO angle (deg) Z (R+/-jX-Ohms) 3.55 3.83 90 11450 - j29848 7.15 5.73 42 136 + j1.6 10.10 6.74 30 2638 + j1314 14.15 6.49 90 224 + j153 D25: Freq (MHz) Gain(dBi) TO angle (deg) Z (R+/-jX-Ohms) 3.55 -0.41 22 21604 - j35919 7.15 1.39 15 110 + j15 10.10 3.79 51 2727 + j2534 14.15 6.84 32 228 + j93 Because the 1 WL delta loop on 40 is a half WL closed loop on 80 meters, its feedpoint is very high, with high reactance--a tough match with even the best ATU. It would take some significant wire juggling to find the precise point where the reactance changes to inductive and passes through zero. Even with a good match, the radiation goes mostly straight up or nearly so for all but the D25. Likewise, but to a lesser degree, matching on 30 meters will not be easy for some networks. On this band, the D25 loses its low angle of radiation and receives well at all angles from about 10 degrees to 70 degrees. On 20, the 40-meter delta loop is a 2 WL loop and has a tame input impedance. However, for the BOT and APX models, the angle of max radiation is straight up. This radiation angle is largely due to the fact that the antenna is functioning like a beam, with the earth as an extra reflector. The D25 model is likely to be outdone by a dipole at 35' (7+ dBi gain, 24-25 degree TO angle). In looking at these results, be sure to round all numbers into ballpark figures. With a low base to these antennas, the surrounding world is going to significantly affect them, and slight changes in the model (and hence, slight variations from the model in the version you build) can make large changes in the numbers, especially the feedpoint impedance values. But the difference between "reasonable" and "very high" should persist in reality. These results do not mean that the upright delta cannot be used at other frequencies, and it may be better than available alternatives for a given home situation. However, best use seems to be as a single-band antenna. If you do use the antenna on other bands, think about adding antennas someday for each of those bands. Horizontal version of the deltas had high radiation angles on 40. These would lower on 20, but still remain high compared to the 15-degree figure for D25. Hence, it is also likely (although I have not modeled them) that tilted versions would also exhibit high radiation angles on most other bands. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Thu Jun 6 08:06:54 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id IAA03415 for ; Thu, 6 Jun 1996 08:06:50 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id IAA03415 for ; Thu, 6 Jun 1996 08:06:50 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175839-42510>; Thu, 6 Jun 1996 08:05:57 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175796-50189>; Thu, 6 Jun 1996 08:05:26 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id IAA139227 for ; Thu, 6 Jun 1996 08:05:23 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id IAA15751; Thu, 6 Jun 1996 08:04:39 -0400 Message-Id: Date: Thu, 6 Jun 1996 08:04:39 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: The omega on deltas (yup, long, erase, etc.) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Compare the delta loop to what? IF one can get the bottom of the antenna above about 15' or so on 40 meters, the APX version appears to make a good all-round antenna for both short and long hauls. For lower bottom-wire installations, the D25 (fed 25% up one sloping wire) offers dx potential compared to other low installations of the delta. Although its gain is low, its reduction of signal (both in and out) at higher radiation angles suggests that it might achieve a superior signal-to- noise ratio on signals at low angles (dx). However, it is not likely to be a sweepstakes or field day winner, where all one wants is US (although it might be useful on one or the other coast). All of this preamble is background for suggesting that the appropriate comparisons among antennas for the low-installation of a delta loop would be various types of vertical antennas. So I modeled a bunch--quickly, so the results are only indicative and no where near absolute. All the verticals used 1.5" diameter aluminum. If they had radials, they were #18 wire (although changing the radials to #12 made no difference). All antennas with radials used 4 27.5' sloping radials, simulating a roof-top installation. (I did not model a ground-mounted vertical, since their efficiency depends on the quality of the radial system--at, above, or below ground.) All antennas were placed over a medium S-N ground. Here is a run down of the models: QW-2030 A full size quarter WL vertical with 4 radials sloping 30 degrees and a base height of 20' QW-2530 A full size quarter WL vertical with 4 radials sloping 30 degrees and a base height of 25' QW-3530 A full size quarter WL vertical with 4 radials sloping 30 degrees and a base height of 35' QW-2545 A full size quarter WL vertical with 4 radials sloping 45 degrees and a base height of 25' QW-3545 A full size quarter WL vertical with 4 radials sloping 45 degrees and a base height of 35' QWL2530 An 18' vertical over 30 degree radials, with a mid-length loading coil (Q=300) to simulate trap verticals (roughly) VDPL66 A full size vertical dipole about 2' off the ground at the bottom. VDPL3625 A vertical dipole about 36' long, fed in the center at the 18' mark (which was 25 above ground) and loaded in each leg's mid point to simulate (roughly) commercial vertical dipoles. VDPL3635 A vertical dipole about 36' long, fed in the center at the 18' mark (which was 35 above ground) and loaded in each leg's mid point to simulate (roughly) commercial vertical dipoles. Here is a table of results, compared to old D25, our 25% up the leg delta loop at 10' and 35' over ground at the base. Feedpoint Z is omitted due to the roughness of the models. Antenna Gain (dBi) Max Radiation angle (degrees) D25-35' 1.39 15 D25-10' 1.12 21 QW-2030 0.45 21 QW-2530 0.57 19 QW-3530 0.70 17 QW-2545 0.62 19 QW-3545 0.83 17 QWL2530 0.55 21 VDPL66 -.07 18 VDPL3625 -.55 22 VDPL3635 -.22 19 First, do not worry about the negative gain numbers. Remember that gain in dBi is relative to an isotropic radiator, and a negative gain means that an antenna would have less radiation in the direction of interest than an isotropic radiator--less, but not none. Many antennas with negative gain numbers do work. The patterns of all these antennas are similar: nothing going straight up or close to straight up, and everything outward at relatively low angles (roughly between vertical angles of 10 degrees up to 45 degrees). The higher base antennas have slightly lower overall lobe angles than the lower base antennas. If you were expecting larger numbers for vertical antennas, these numbers may surprise you. Antennas many wavelengths above ground (like a 2-meter ground plane, etc.) are effectively isolated from real ground effects. However, on 40 meters, ground reflection and absorption, even beyond the limits of a ground plane, play a big role in the far field strength. You can get artificially high numbers by placing these same antennas over "perfect" ground, but unless you plan to copper plate your entire yard and to keep it polished (or some equivalent), you cannot achieve those numbers. So, with models of real antennas over simulated real ground conditions, the advantages of the D25 begin to show. Its max gain over the verticals is real and can reach up to 2 dB (almost half an S-unit, which can make a difference is weak signal snagging). Remember that the D25 is bi-directional broadside to the antenna plane: this is where it gets its gain over the omnidirectional verticals, and off the sides, the gain drops a few dB. These results do not mean that the verticals are poor antennas. Rather, in putting up a Butternut, Hustler, 14 AVQ, R-7000, GAP, etc., we give up a little gain to get multi-band omni-directional performance. But the delta remains cheaper. Proving once again that there is no magic in antennas: to get something you give up something else. So, in your planning, always ask yourself: what do you want? what are you willing to give? I suspect that this is now more than enough on delta loops. wish I could have shown patterns on e-mail, but that would also have made each message much longer. Enjoy building your loop while the weather is good. I think I'll take a small vacation. (I heard those sighs of relief from the disinterested. . .) -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Thu Jun 6 11:24:06 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA12422 for ; Thu, 6 Jun 1996 11:24:05 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA12422 for ; Thu, 6 Jun 1996 11:24:05 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175873-50189>; Thu, 6 Jun 1996 11:14:30 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174985-42510>; Thu, 6 Jun 1996 11:04:49 -0400 Received: from dns.okc (dns.oklahoma.net [206.190.50.2]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id LAA84814 for ; Thu, 6 Jun 1996 11:03:58 -0400 Received: from dub .oklahoma.net by dns.okc (SMI-8.6/SMI-SVR4) id KAA25362; Thu, 6 Jun 1996 10:06:37 -0500 Message-Id: <199606061506.KAA25362@dns.okc> Date: Thu, 6 Jun 1996 10:06:37 -0500 Reply-To: dub@oklahoma.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "j.w. thornton" To: "Low Power Amateur Radio Discussion" Subject: Loop Ants: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: dub@okc.oklahoma.net X-Mailer: Windows Eudora Pro Version 2.1.2 X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Hi List: Been followin the saga of the loop ant with interest. One of the more common ants found on (and highly touted), would be the horizontal loop, one wavelength @80 meters, fed with tuned feeders for all bands 80 & above. My own is @35' height, 3 sided, corner fed with homebrew 12ga ladder line to a tuner. Essentially, what I have retained from reading many opinions from many authors, is that the ant radiates primarily as a "cloud warmer" at the one wavelength design freq, while the gain increases and angle of radiation decreases as we move up to the higher bands. Be interesting to see this one modeled. "72" J. W. (Dub) Thornton WA5YFY Minco, Ok. From owner-qrp-l@Lehigh.EDU Thu Jun 6 11:55:06 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA13929 for ; Thu, 6 Jun 1996 11:55:02 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA13929 for ; Thu, 6 Jun 1996 11:55:02 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175881-22284>; Thu, 6 Jun 1996 11:49:32 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175821-50189>; Thu, 6 Jun 1996 11:41:37 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id LAA84859 for ; Thu, 6 Jun 1996 11:41:29 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id LAA16802; Thu, 6 Jun 1996 11:40:48 -0400 Message-Id: Date: Thu, 6 Jun 1996 11:40:47 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Right-Angle deltas (ETC.) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Right-Angle Delta Loop: Side-Fed Sorry, but I lied. Just could not resist trying out a different version of the delta loop on the modeling machine. What a surprise, and worth bringing to the attention of delta-contemplators. Let's keep this much the same: #12 copper wire, medium S-N ground. But let's change the look of the delta from its equilateral triangle shape hat we have been investigating. Using a bottom wire and an upward apex, lets change the angle of the apex from 60 degrees to 90 degrees. Sort of like this: /\ /A \ c/ \ b /B C\ ---------- a Now this will look different on each screen, and even more different on the printer, but let angle A = 90 degrees, and angles B and C = 45 degrees. A resonant length for 7.15 MHz on the modeling machine gives side lengths this way: Side a = 60.8'; sides b and c each = 43.0' The total antenna height is 30.4' from bottom wire to apex, which may let you raise the antenna a bit higher for a fixed tall antenna support--and that would be good. Now let us consider only the use of Side-feeding to get vertical antenna benefits from this arrangement. Go 1/6th the way up one of the sloping sides and feed it there. (That is 7'2" on this 7.15 MHz model, but +/-6" will make very little difference, although it may affect the feedpoint Z.) Now, on the equilateral triangle version of the delta, the feedpoint impedance was relatively constant wherever we fed it--between 110 and 140 ohms, which is a quite narrow range. Not so on this version. Feed the antenna at the middle of the bottom, and its Z is about 200 ohms. But, feed this version at the 1/6th-up-the-side point, and you can feed it with coax. See the table below. Use a 1:1 balun if you like. How you prop up the connection is a matter of individual ingenuity. But, being flatter, it will perform poorer than the equilateral delta used as a side-fed vertical at the 25% point, said the reasonably skeptical thinker about antennas. But sometimes with antennas, thinking will get you in trouble. The right-angle delta performs a little--not super much, but a significant amount--better than the equilateral delta in this configuration. Let's look at some modeling outputs: Height in feet degrees degrees Std Delta Bot ht Top ht Gain (dBi) TO angle BW [gain TO] 35 65.4 1.97 16 23 1.39 15 25 55.4 1.97 18 28 1.44 17 15 45.4 1.77 21 34 1.28 20 10 40.4 1.57 23 37 1.12 21 Note that for any bottom height, the equilateral version will be about 11.5' taller. For a given anchor mast/tower/tree/etc., you can now raise the baseline horizontal wire by that much--and 10' of further elevation helps either the gain or the TO angle or both. The BW=beamwidth, the vertical width of the radiation pattern to the points either side of maximum where the power drops to 1/2 maximum. Note that it is narrower (with less high angle radiation or receiving interference to dx) as you place the antenna higher. (The standard delta exhibits the same increasing beamwidth as the baseline height is lowered.) The gain is broadside to the face of the delta. To the edges, the gain is down 4 dB or so. The pattern makes a nice oval when viewed from on top (azimuth pattern). So have a pair of favored directions (or use an omnidirectional vertical). The feedpoint impedance is about 50 ohms roughly resonant at the 35' baseline height, about 56 ohms at 25', 69 ohms at 15' and 79 ohms at 10'. Baseline height and exact position along the sloping wire, counting from the bottom wire upward, will play a role in the exact impedance, but coax ought to do the trick. I did not invent the 90-degree delta--Moxon makes reference to this shaping in his book--although analysis is confusing. Moreover, some folks who have claimed to use coax to feed deltas have probably flattened them into right- angle versions--or something close. Will this antenna work? All I can say is that it should, but I cannot say for certain that it will. In fact, it may even be covered in ON4UN's book (which is not at hand as I look this model over). So who will try it--or discover they have tried it due to backyard limitations? Remember, in this application, keeping the delta upright (vertical) is important--and getting as high as feasible is also beneficial. I'll look forward to hearing about experiments. Now I really will go on vacation and give deltas a rest. (Famous last words.) -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Thu Jun 6 16:07:45 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id QAA28514 for ; Thu, 6 Jun 1996 16:07:43 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id QAA28514 for ; Thu, 6 Jun 1996 16:07:43 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175912-22284>; Thu, 6 Jun 1996 15:59:18 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174184-22284>; Thu, 6 Jun 1996 15:10:31 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id PAA78261 for ; Thu, 6 Jun 1996 15:07:06 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id PAA16423; Thu, 6 Jun 1996 15:04:42 -0400 Message-Id: Date: Thu, 6 Jun 1996 15:04:39 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Re: Loop Ants: In-Reply-To: <199606061506.KAA25362@dns.okc> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: "j.w. thornton" X-Cc: Low Power Amateur Radio Discussion X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Dub, Your horizintal plane loop, 1 wl at 80 meters, up 35' plays approximately like this: (forward will always mean in the direction of the feedpoint apex to your triangle. I cannot be exact, becaue I have only general descriptions to go by, but this will be ballpark) Freq Input Z Gain TO angle 3.55 95 + 4 6.31 90 Gain at 45 deg = 3.25 7.15 235 + 210 6.96 47 10.12 115 - 272 6.63 36 F-B ratio = 4 dB 14.15 305 + 175 10.05 28 F-B = 2 dB; pattern has side ears 18.1 435 + 715 12.01 20 F-B = 3 dB; bigger ears 21.1 175 + 280 11.68 17 F-B = 3 dB: 6-point star pattern 24.95 485 + 565 13.50 15 F-B = 3.5 dB; long Front and back points with frilly side ears 28.1 320 + 405 13.94 13 F-B = 4.5 dB; same as 24.95 Note that feedpoint values should be within reach of most ATUs. Angle high until 20 meters, then medium til 15, then good for dx, but side-to-side beam width of main lobe front and back gets very narrow on two upper bands. All in all, not a bad one-wire all-band antenna. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Fri Jun 7 10:30:53 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id KAA16835 for ; Fri, 7 Jun 1996 10:30:51 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id KAA16835 for ; Fri, 7 Jun 1996 10:30:51 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174453-46218>; Fri, 7 Jun 1996 10:30:18 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174171-52103>; Fri, 7 Jun 1996 10:29:17 -0400 Received: from scubed.com (server1b.scubed.com [192.31.68.21]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id KAA44943 for ; Fri, 7 Jun 1996 10:29:03 -0400 Received: from inferno.scubed.com by scubed.com (S3.4/solaris-main) id HAA01029; Fri, 7 Jun 1996 07:28:58 -0700 Received: from [192.31.66.229] by inferno.scubed.com (S3.4/s3-sgi-5) id OAA28121; Fri, 7 Jun 1996 14:27:52 GMT Message-Id: Date: Fri, 7 Jun 1996 08:30:54 -0600 Reply-To: ji3m@scubed.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: ji3m@scubed.com (James R. Duffey) To: "Low Power Amateur Radio Discussion" Subject: Multiband Delta Loops (long of course) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-To: "L. B. Cebik" X-Cc: qrp-l@Lehigh.EDU X-Sender: ji3m@inferno.scubed.com X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO L.B.-I enjoy your delta loop modeling efforts. They raise the general technical level of the group and are educational. Keep these antenna modeling efforts coming. I have a few comments on your multiband loop efforts. I suggest that a 30 M loop is more useful than a 40M one for multiband use. It will have reasonable feedpoint impedence at 40M and still be reasonably efficient. On 20M it is a wavelength and half loop with reasonable feedpoint and low angle radiation. On 17M it is still below 2 wavelengths and has a reasonable radiation pattern-at least this is what my simple modeling showed. It can be difficult to feed on this band though (more about that later). It suffers from extensive pattern breakup above 20 MHz though and another antenna should be used if low angle operation is desired. The antenna can be fed as is on 80 M with poor results due to the high input impedence, but it is preferred to feed it as a vertical by tieing the feeder ends together and feeding it against a counterpoise or ground as a vertical, or feeding one side of the feeder and grounding the other side. This second feed method makes a folded monopole, raising the radiation resistance and increasing efficiency slightly. The antenna can work on 160M too, I feed one side of the feeder against ground or counterpoise as a quarter wavelength vertical (Marconi). This is not too efficient, but allows me to get on the band and is easy to feed (primarily due to large losses I suspect). Most 160M antennas are not too efficient so it is not as much of a compromise as one would think. The 30M loop is best fed with 5M of feed line. This gives 40 M of wire in the antenna and feedline. This will work best (gives close to a resistive feedpoint) for the conventional bands, 160, 40, 80, 20. It will also load well on 15 and 10, but with appreciable high angle radiation. Another 2.5M or so of feedline will give a reasonable feedpoint on 30 M with 45M (1 1/2 wavelengths of wire in the antenna/feedline, and another 2 to 2.5M added to that for a total of 50M (3 wavelengths) in the antenna feedline system will give a reasonable feedpoint on 17 (and 12, but again the pattern is not optimized for low angle radiation. The above antenna can be supplemented with a 15M or 17M loop for (17M), 15, 12, and 10 M operation. This could also be fed as a vertical on the lower bands. Keep it coming. Your posts are well received here.-Duffey KK6MC/5 James R Duffey KK6MC/5 DM65 30 Casa Loma Road Cedar Crest, NM 87008 From owner-qrp-l@Lehigh.EDU Fri Jun 7 11:07:07 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA18543 for ; Fri, 7 Jun 1996 11:07:05 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA18543 for ; Fri, 7 Jun 1996 11:07:05 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <176041-52103>; Fri, 7 Jun 1996 11:03:55 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174171-46473>; Fri, 7 Jun 1996 11:02:29 -0400 Received: from conciliator.acsu.buffalo.edu (root@conciliator.acsu.buffalo.edu [128.205.7.20]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id LAA59442 for ; Fri, 7 Jun 1996 11:02:19 -0400 Received: from ubppp-039.ppp-net.buffalo.edu (ubppp-039.ppp-net.buffalo.edu [128.205.222.103]) by conciliator.acsu.buffalo.edu (8.7.4/8.7.3) with SMTP id LAA00314; Fri, 7 Jun 1996 11:02:03 -0400 (EDT) Message-Id: <31B86E92.4096@acsu.buffalo.edu> Date: Fri, 07 Jun 1996 11:01:54 -0700 Reply-To: msadams@acsu.buffalo.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Mark S. Adams" To: "Low Power Amateur Radio Discussion" Subject: Re: Multiband Delta Loops (long of course) References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: ji3m@scubed.com X-Cc: Low Power Amateur Radio Discussion X-Mailer: Mozilla 2.0 (Win16; I) X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Hi Gang, It is interesting to note in Jim Duffy's post on multibanding a delta cut for 30M instead of 40M that the feeding of 17M is difficult. I have found that my delta which is cut for 40M will not load on 17M. I have tried 3 different antenna tuners and cannot make the MFJ SWR analyzer happy. Best SWR is about 3.6:1. This is more than I care to risk with my HW-9. After all, it has brand new finals. Also, the SWR peak is super narrow. A few kcs off the 3.6:1 point sends the SWR sky high. I have thought that maybe adding/subracting a few feet of antenna wire would help and Jim's analysis seems to confirm this. I just might try shortening my loop to about XXX' from 142' to get 17M to play. I would just hate to lose 20M in the process, even though the 2 wavelenghts on 20 is not so good. Ideally I would like 40/30/20/17 to play well. 17M would be a plus. folks tell me it is a great qrp band. Well, since my broken pelvis still isn't healed yet I geuss I will resist the urge to play with the antenna just yet! -- 72's de Mark, aka N2VPK TMPS 1996 Q's=58 WAS=19 Confirmed=00 DX=08 AL CA CO CT IN FL KY MA MI MD ME NC NY PA SC SD TN TX WI CT3 EA ES HC LY OZ VE1 6W1 From owner-qrp-l@Lehigh.EDU Fri Jun 7 11:07:08 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA18545 for ; Fri, 7 Jun 1996 11:07:07 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id LAA18545 for ; Fri, 7 Jun 1996 11:07:07 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <172272-46218>; Fri, 7 Jun 1996 11:04:32 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175528-52103>; Fri, 7 Jun 1996 11:02:33 -0400 Received: from Fe3.rust.net (Fe3.rust.net [204.157.12.254]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id LAA121445 for ; Fri, 7 Jun 1996 11:02:32 -0400 Received: from LOCALNAME (bfld-34.rust.net [204.157.51.134]) by Fe3.rust.net (8.7.4/8.7.3) with SMTP id LAA03149 for ; Fri, 7 Jun 1996 11:01:54 -0400 (EDT) Message-Id: <31B86E73.59BB@rust.net> Date: Fri, 07 Jun 1996 11:01:23 -0700 Reply-To: hires@rust.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Floyd Soo, KF8AT" To: "Low Power Amateur Radio Discussion" Subject: 40 Meter Mobile Loop MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: QRP-L X-Mailer: Mozilla 2.01KIT (Win16; U) X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Gang, With all the attention that has been paid to the loops and delta loops, I wonder if anyone has successfully used a 40 meter delta loop from an automobile? Seems to me that strategically mounted masts on the corner of the vehicle (self-supporting, of course), some fine wire, maybe even some pulleys to move the feedpoint around to change the pattern some. I guess the masts would have to stay within the 13'6" maximaum height, so you won't leave the antenna at the first overpass you come to. Has anyone used a suitable (small and portable) transmatch with their 40 meter mobile loop? I wonder if this antenna can be modeled on a computer program... (Sorry for the bandwidth, but I couldn't resist! HI HI!) 72 and see you all on Field Day, Floyd, KF8AT From owner-qrp-l@Lehigh.EDU Mon Jun 10 21:07:13 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA12652 for ; Mon, 10 Jun 1996 21:07:08 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA12652 for ; Mon, 10 Jun 1996 21:07:08 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174405-42929>; Mon, 10 Jun 1996 21:06:36 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174353-54702>; Mon, 10 Jun 1996 21:05:26 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id VAA25139 for ; Mon, 10 Jun 1996 21:05:11 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id VAA19979; Mon, 10 Jun 1996 21:03:54 -0400 Message-Id: Date: Mon, 10 Jun 1996 21:03:53 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Horizontal delta loops MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: qrp-l@lehigh.edu X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Horizontal Deltas on all bands While I was on the road, several requests came in to model various antennas, mostly versions of the delta loop. While I do not have the time to do every antenna, I shall from time to time do a collection so that folks can see the trends and relate them to other information they have. An investigation of a very specific antenna would require more information at the input side than most requests have provided and take considerable time to ensure that the model was as close to the individual's real situation as I can make it. What I can do in fairly short order is to model generic antennas under various circumstances as a broad guide to builders, letting the individual extrapolate for their specific situation. For this exercise, let's look at the delta loop in the horizontal plane, fed at the apex. Feeding it across the way, at the center of the base wire will not change matters much. However, feeding it off center and off apex will likely change matters on all but the band for which the antenna is resonant. Moreover, we cannot assume that these ballpark numbers apply to the same delta loop when upright. The loop is #12 copper wire, and is at a height of 35', since this is a very popular amateur height. 1 wl at 80 meters (previously copied from an e-mail to Dub) Freq Input Z Gain TO angle Comments 3.55 95 + 4 6.31 90 Gain at 45 degrees = 3.25 dBi 7.15 235 + 210 6.96 47 10.12 115 - 270 6.63 36 F-B ratio 4 dB 14.15 305 + 175 10.05 28 F-B 2 dB, pattern has side ears 18.1 435 + 715 12.01 20 F-B 3 dB, bigger ears 21.1 175 + 280 11.68 17 F-B 3 dB, 6 point star pattern 24.95 485 + 565 13.50 15 F-B 3.5 dB, long, narrow F-B lobes, with frilly side ears 28.1 320 + 405 13.94 13 F-B 4.5 dB; same as 24.95 As noted earlier, the feedpoint Zs should be within the reach of most ATUs, and the angles are reasonable for an antenna that is low on the low bands and 1/2 wl up at 10 meters. About as good an all-band wire as one can make at this height above ground. Values not too different from a square or rectangular loop in the same plane or same height, although patterns will vary somewhat due to the change in geometry. 1 wl at 40 meters Freq Input Z Gain TO angle Comments 3.55 2740 - 20000 3.12 88 Gain at 45 degrees = 1.64 dBi 7.15 150 + 1 6.03 85 Gain at 45 degrees = 4.88 dBi 10.12 2655 + 510 5.36 46 14.15 255 + 75 8.06 28 Diamond pattern 18.1 665 - 1655 8.76 21 Figure-8 pattern 21.1 106 + 136 8.38 18 Hexagon pattern 24.95 905 - 1465 7.99 16 Amoeba pattern 28.1 290 + 180 10.64 14 8-lobe pattern This smaller delta loop at the same 35' up performs less well that the 80- meter loop. 80 meters has a lot of reactance. The number of cases of R or X above 1000 suggests that some tuners may have a hard time matching the system without some lucky choices of line length or some adjustment of the feedpoint (and the latter will alter the pattern somewhat). Gains are lower across the board. 1 wl at 30 meters Freq Input Z Gain TO angle Comments 3.55 19 + 2340 -.95 63 7.15 85 - 1120 5.45 67 Gain at 45 degrees = 4.91 dBi 10.12 151 + 3 5.35 45 14.15 2950 + 1030 6.17 30 18.1 330 + 550 8.76 21 Figure-8 pattern 21.1 330 + 550 8.76 19 Diamond pattern 24.95 890 - 1760 8.79 16 Figure-8 pattern 28.1 100 - 220 8.70 14 Hexagon pattern Low-band performance of this loop is not really very good. 80 and 40 will likely present matching difficulties with select line lengths or altered feedpoints. Upper band performance does not match the other models. The upshot of this exercise is that the 80-meter loop is perhaps the best all- band performer among delta loops in the horizontal plane at low heights (here 35' up). It requires a space a little over 40' by 80' and needs three hang points. Remember that if you change the feedpoint or the geometry, patterns and input Z will likely change. However, an 80 meter rectangular or square loop in the same plane and height will likely give somewhat similar performance to the comparable delta loop in terms of being accessible to most ATUs, having about the same TO angles, and about the same gains per band. going larger than an 80 meter loop, but not all the way to 160 meters, may alter the feedpoint impedances for better or worse, but is not likely to improve the performance by substantial amounts--only increased elevation can do that for a single element antenna. I'll look at upright deltas cut for various bands in another exercise. This is enough bandwidth for this time. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Tue Jun 11 10:45:50 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id KAA19690 for ; Tue, 11 Jun 1996 10:45:50 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id KAA19690 for ; Tue, 11 Jun 1996 10:45:50 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175429-54746>; Tue, 11 Jun 1996 10:41:41 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175425-46299>; Tue, 11 Jun 1996 10:36:17 -0400 Received: from dns.okc (dns.oklahoma.net [206.190.50.2]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id KAA50925 for ; Tue, 11 Jun 1996 10:35:35 -0400 Received: from dub .oklahoma.net by dns.okc (SMI-8.6/SMI-SVR4) id JAA15969; Tue, 11 Jun 1996 09:38:20 -0500 Message-Id: <199606111438.JAA15969@dns.okc> Date: Tue, 11 Jun 1996 09:38:20 -0500 Reply-To: dub@oklahoma.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "j.w. thornton" To: "Low Power Amateur Radio Discussion" Subject: RE: Horiz. Delta Loops Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: dub@okc.oklahoma.net X-Mailer: Windows Eudora Pro Version 2.1.2 X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Hi LB & gang: Very interesting and informative thread, this one on loop antennas. I have used the 80mtr delta loop @35', tuned feedline for several years, and find it to be a very good all (cept 160M) ant. I have read and re-read every article I could find on loop ants. This single posting by LB Cebik sure makes it easy to understand in a general way how the antenna is acting. LB, thanks for your fine efforts. I know this takes a lot of time and effort, but it is appreciated. J. W. (Dub) Thornton WA5YFY Minco, Ok. From owner-qrp-l@Lehigh.EDU Tue Jun 11 17:50:42 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id RAA17391 for ; Tue, 11 Jun 1996 17:50:39 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id RAA17391 for ; Tue, 11 Jun 1996 17:50:39 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <175590-54746>; Tue, 11 Jun 1996 17:49:01 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174648-53975>; Tue, 11 Jun 1996 17:14:22 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id QAA106870 for ; Tue, 11 Jun 1996 16:54:09 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id QAA23505; Tue, 11 Jun 1996 16:52:29 -0400 Message-Id: Date: Tue, 11 Jun 1996 16:52:29 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Horiz. deltas at 45' MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Horizontal Deltas on all bands (45' this time) Now the question is what happens to a horizontal delta loop at 45', the other favorite ham antenna height. The loop is #12 copper wire, and is at a height of 45', over medium earth. All other heights you will have to interpolate and extrapolate, since the behavior of the loop is consistent with what happens to any horizontal antenna when elevated further. Compare the results of the 35' up model, and you will see the TO angle go down some on most bands, and the gain go up a bit. Feedpoint is one apex of the equilateral triangle, and any strong lobes are along this axis, with the slightly stronger signal to the apex direction. 1 wl at 80 meters (total wire length = 1020/f) Freq Input Z Gain TO angle Comments 3.55 115 + 8 6.77 89 7.15 280 + 200 7.28 41 10.12 115 - 245 7.22 27 Hex pattern 14.15 280 + 225 10.60 22 Pattern has side ears 18.1 460 + 770 12.57 16 Bigger ears 21.1 180 + 325 12.25 14 6 point star pattern 24.95 515 + 650 13.97 12 Narrow lobes, with frilly ears 28.1 335 + 475 14.30 10 Same as 24.95 1 wl at 40 meters (total wire length = 1045/f) Freq Input Z Gain TO angle Comments 3.55 1670 - 15000 4.15 86 7.15 160 + 5 5.42 51 10.12 3120 + 705 5.92 33 14.15 225 + 160 8.65 22 Diamond pattern 18.1 455 - 1370 8.74 17 Figure-8 pattern 21.1 120 + 235 8.42 14 Hexagon pattern 24.95 630 - 1215 8.61 13 Wiggly fig. 8 28.1 330 + 290 10.77 11 8-lobe pattern 1 wl at 30 meters (total wire length = 1050/f) Freq Input Z Gain TO angle Comments 3.55 19 + 2340 0.42 58 7.15 90 - 1135 5.31 46 10.12 120 - 5 6.05 32 14.15 3580 + 385 6.17 22 diamond pattern 18.1 265 - 315 7.33 17 diamond pattern 21.1 360 + 525 8.73 15 diamond pattern 24.95 930 - 1795 9.06 12 Figure-8 pattern 28.1 100 - 220 8.92 11 Hexagon pattern Increased elevation can improve performance for a single element antenna. However, our increase of 10' did not make a very substantial difference in performance, because it was not a very significant increase in height. Input impedances are close between models. The differences might only be noticed in models and not in actual operation. Since you can use the 35' and 45' data to extrapolate for other typical ham heights (or see the article on the affects of heights on ham antennas I did for Communications Quarterly a few years ago), this will be the last notes on horizontal deltas and loops. I've been warned about burning out. . . -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Wed Jun 19 21:32:12 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA17148 for ; Wed, 19 Jun 1996 21:32:10 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA17148 for ; Wed, 19 Jun 1996 21:32:10 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174607-31577>; Wed, 19 Jun 1996 21:31:50 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174592-50522>; Wed, 19 Jun 1996 21:30:39 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id VAA107062 for ; Wed, 19 Jun 1996 21:30:09 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id VAA06679; Wed, 19 Jun 1996 21:30:26 -0400 Message-Id: Date: Wed, 19 Jun 1996 21:30:25 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: The right-angle delta loop, part 2 MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Follow-up on the right-angle upright delta loop, side fed I did a little more work on the right angle delta loop as a superior vertical radiator on 40 to the equilateral delta loop. As you recall, the right angle loop is shorter by about 10' than the equilateral loop, allowing it to be higher by that amount for a constant height top support. That is advantage number one. The second advantage is a closer match (depending upon the height of the horizontal base wire) to 50 or 75 ohm coax. The third advantage is somewhat less sensitivity to the position of the feedline along the sloping wire. And the fourth is somewhat greater gain at the angle of max radiation in that flattened vertically polarized pattern prized by dxers. The exact length of a right-angle delta depends on height. With the base at 35' and the apex at 65.4', the length at 7.15 MHz is about 1050/f or 146.8', with the sloping sides 43' long each and the base 60.8' long horizontally. With the base only 10' above ground, and the apex 40.2' high, the sloping sides are 42.8' each and the base is 60.6' long, for a total of 146.2' of wire, or 1045/f at 7.15 MHz. At the higher level, you can feed the sloping wire anywhere from 2% to about 25% along the wire (but not at the bottom corner) with little change in gain or input impedance. Both stay constant: gain 1.96 dBi; TO angle 16 degrees; Z = 49.3 to 51.4 ohms with less than 1 ohm reactance (in the model, which has no ground clutter). However, the least horizontal radiation occurs between 12 and 15 degrees along the wire--the 6' from the bottom corner region. (For comparison, the equilateral delta had a gain of about 1.4 dBi, with a TO angle of 15 degrees, and a 100-ohm feedpoint Z.) With the base only 10' off the ground and ignoring ground clutter (which a real antenna builder cannot do), the region of constant performance extends from about 4% to about 20% along the sloping wire, with the least horizontal radiation in the 13 to 16% range, again in the 6 to 7' from the corner vicinity. Gain is about 1.54 dBi, TO angle is 23 degrees, and feedpoint impedance is 77.5 to 79 ohms with negligible reactance. (For comparison, the equilateral delta with a 10' high base wire has a gain of about 1.12 dBi, a TO of 21 degrees, and a feedpoint Z of about 160 ohms.) The lower level right- angle delta loop is a better match for 75 ohm coax, but 50 ohm coax will show only about a 1.4:1 SWR, meaning insignificant loss from mismatch. The reason to use the feedpoint position of least horizontal radiation is that on either side of the region of best vertical performance, a secondary higher angle lobe grows. It is not very significant, but it does permit high-angle QRM/QRN to increase. If you use this antenna at all, it will be for its low angle properties, not its gain, and you will want the best signal to noise ratio possible on weak dx signals. Decreasing high-angle input decreases domestic noise, whether QRM or QRN (although it will not eliminate the neighbor's table saw noise). Hence, getting the feedpoint up to the 13% mark or so is useful, but there is a +/- 2 to 3% region of virtually no difference in both the high and low versions (meaning the region is there at all intermediate levels for the bottom wire). You can also interpolate probable feedpoint impedance from these limiting figures. All models were made over medium quality ground (Somerfeld-Norton analysis) with no ground radials, counterpoises, or other ground improvements. The delta loop needs no radials. Like the equilateral delta, the right-angle delta is not a sterling performer on other bands, even when the feedpoint is moved to the center of the bottom wire or to the top apex, with quite high values of resistance and reactance on 30 meters, medium high values on the WARC bands, and useable numbers on the harmonics of 7 MHz. But it will do ok, especially on the uppermost HF bands, if the bottom wire is at least 20' up. 80 meters, of course, is out for any closed loop 40 meter antenna. Remember: the loop gets a little smaller with smaller wire sizes (the opposite of linear elements that get smaller with fatter wire). And, unlike the equilateral loop that shows a small range of feedpoint Z change around the loop, the low Z values occur only along the sides. At the apex or at the center of the bottom wire, the Z goes to 200-250 ohm range on 40 meters. However, the right-angle delta shines as a 40-meter 1 wl loop fed on the side with a close-to-coax Z for maximizing vertical performance and dx work. Hope this data is useful. -73- LB, W4RNL From owner-qrp-l@LeHigh.EDU Fri Jun 21 21:54:37 1996 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA28922 for ; Fri, 21 Jun 1996 21:54:35 -0400 (EDT) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id VAA28922 for ; Fri, 21 Jun 1996 21:54:35 -0400 (EDT) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174398-21461>; Fri, 21 Jun 1996 21:53:58 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174388-67798>; Fri, 21 Jun 1996 21:52:53 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id VAA42175 for ; Fri, 21 Jun 1996 21:52:46 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id VAA13259; Fri, 21 Jun 1996 21:52:47 -0400 Message-Id: Date: Fri, 21 Jun 1996 21:52:47 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@LeHigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: the 40 meter loop on 80--opened MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO Dave, W6EMD suggested the a loop for 40 opened directly opposite the feed point would work on 80. Models indicate that it would indeed reduce the feedpoint impedance from very high values of both Resistance and reactance (both in the 10s of thousands of homs). However, it may lower the impedance too far for efficiency--something in the range of 5-10 ohms for upright delta loops with either the horizontal wire high or the apex high. The loop may load with an ATU, since the reactance is also fairly low, but I have to wonder about the efficiency of such antennas. The smallest resistance at contacts will convert a greater percentage of the fed power into heat rather than radiation. Hence, I have to believe that this is usable, but not optimal for 80. But without a lot od real estate, and sky hooks, not too much is truly optimal for 80--but a lot of stuff will work. -73- LB, W4RNL From owner-qrp-l@Lehigh.EDU Sat Jun 22 10:05:07 1996 Received: from boss.cs.OhioU.Edu (root@boss.cs.ohiou.edu [132.235.1.1]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id KAA01659 for ; Sat, 22 Jun 1996 10:05:06 -0400 (EDT) X-Received-x: from boss.cs.OhioU.Edu (root@boss.cs.ohiou.edu [132.235.1.1]) by oucsace.cs.ohiou.edu (8.7.1/8.7.1) with ESMTP id KAA01659 for ; Sat, 22 Jun 1996 10:05:06 -0400 (EDT) Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by boss.cs.OhioU.Edu (8.7.1/) with ESMTP id OAA01599 for ; Sat, 22 Jun 1996 14:05:03 GMT X-Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by boss.cs.OhioU.Edu (8.7.1/) with ESMTP id OAA01599 for ; Sat, 22 Jun 1996 14:05:03 GMT Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <174265-21484>; Sat, 22 Jun 1996 07:56:06 -0400 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174188-25833>; Sat, 22 Jun 1996 07:55:22 -0400 Received: from utkux4.utcc.utk.edu (UTKUX4.UTCC.UTK.EDU [128.169.76.11]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id HAA59472 for ; Sat, 22 Jun 1996 07:55:18 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id HAA29979; Sat, 22 Jun 1996 07:55:22 -0400 Message-Id: Date: Sat, 22 Jun 1996 07:55:21 -0400 (EDT) Reply-To: cebik@utkux.utcc.utk.edu Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "L. B. Cebik" To: "Low Power Amateur Radio Discussion" Subject: Re: Loops In-Reply-To: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: Bob_Tellefsen-CNSE97@email.mot.com X-Cc: qrp-l@Lehigh.EDU X-Sender: cebik@utkux4.utcc.utk.edu X-Listprocessor-Version: 7.2 -- ListProcessor by CREN Status: RO On 20 Jun 1996 Bob_Tellefsen-CNSE97@email.mot.com wrote: > LB > I've been reading your posts about modeling the delta loops. > I used to use them myself, but now run a pair of 40m diamond loops in phase. > I use a 50' tv pushup mast, and the sides of the diamond bulge out slightly, > so the longer axis is horizontal. > > The bottom corner is only about 6 ft above ground, and I feed at the side for > vertical polarity. > > Sometime, if curiousity moves you, I'd be interested in what the models say > about the comparison between the diamond loop and a delta on a comparable > mast. > > I've had good luck with both, but thot I'd use the diamond to more closely > approximate a vertical dipole. > > 72/73 Bob N6WG > Bob, Your use of a side-fed quad loop set up as a diamond is interesting and worth sharing. Using your max height as 50' and min height as 6', models suggest a total side span of 57.3', compared to the height span of 44'. This is not much of a bulge. In this same space, one can fit an equilateral delta loop, with the bottom at 8' and the top at between 49 and 50' So this is the model I used for comparison. I took data on 2 versions with the bottom wire low, one fed at bottom center (BOT) and the other fed about 25% up the side for maximum vertical radiation (SID). I also inverted the delta and fed it at the lower apex (APX). These I compared with the model of your loop (DIA). I used the SID model, having the lowest angle of max radiation (TO) of the deltas. So for BOT and APX, you will see two sets of gain numbers, one for the natural TO of the model, the other for 22 degrees, the TO of SID. I give in the table also the total wire length of the loop and the general formula for that length, just as a reference. It will vary with antenna height and wire size (as well as for insulated vs. uninsulated wire). Model Gain TO R +/- jX L Formula L SID 1.03 dBi 22 deg 172 + 1.8 145.2' 1038/f BOT 3.21 68 103 + 7.5 144' 1030/f -.76 22 APX 5.64 43 134 + 1.4 145.2' 1038/f 3.45 22 DIA 1.30 21 132 - 2.9 144.5' 1033/f Note that the side-fed delta and the side-fed diamond have very comparable figures, with the diamond having slightly more gain. The gain is a function of the higher feedpoint height. Both the DIA and the SID minimize horizontal radiation (which is mostly at higher angles) so that it is at least 20 dB below max gain and thus contributes little to the overall field. The patterns for BOT, SID, and DIA are broad ovals broadside to the face of the loop. The pattern of APX is more peanut-shaped in the same broadside plane. The APX, if mechanically feasible, is perhaps the best general purpose 40 meter antenna of the group, with good one hop and multi-hop gain. For DX, it has more gain on both transmission and reception, but it does receive well at higher angles, allowing more short distance noise and QRM into reception on a given frequency. A delta with the horizontal wire at the near 50' level and fed at the bottom apex has more gain at the 22-degree angle than either SID or DIA. However, it max gain at 43 degrees would likely mean greater noise and QRM from nearer (domestic) stations, reversing the strength relationship between nearer and more distant skip stations. If we assume that minimum gain for reception is achieved by all the models, then the antennas with a lower natural gain at higher angles may permit better reception of weak dx. However, transmitted gain will also be lower at the 22-degree angle for the lower gain vertically polarized antennas. On your question of approximating a vertical antenna (without need for a ground radial system), either SID or DIA fill that bill equally. Consider the mechanics: One 50' suspension point, a 6' bottom point, and side points 57.3' apart and only 28' high. This may be feasible for some folks and give some improvement over the side-fed delta. It can also be bottom fed, have the peak opposing the feedpoint opened for possible 80-meter use, be fed at the bottom in parallel as a fat-wire vertical, etc. There may be possibilities here for other builders, which is why I am sharing these notes on qrp-l. I did not model phased loops because well-phased vertical antennas add about 3 dB gain in the favored direction with a cardioid pattern, where front-to-back ratio is dependent on getting just the right degree of phasing for the exact distance apart--the results would simply have parallel the differences between SID and DIA. Hope these notes are useful to you. -73- LB, W4RNL