From msadams@acsu.buffalo.edu Tue Jul 2 16:05:42 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174761-18245>; Tue, 2 Jul 1996 12:05:16 -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 MAA56575 for ; Tue, 2 Jul 1996 12:04:46 -0400 Received: from ubppp-013.ppp-net.buffalo.edu (ubppp-013.ppp-net.buffalo.edu [128.205.222.77]) by destrier.acsu.buffalo.edu (8.7.4/8.7.3) with SMTP id MAA25262; Tue, 2 Jul 1996 12:04:17 -0400 (EDT) Message-ID: <31D9AA04.2899@acsu.buffalo.edu> Date: Tue, 02 Jul 1996 16:00:20 -0700 From: "Mark S. Adams" Organization: SUNY/Buffalo X-Mailer: Mozilla 2.0 (Win16; I) MIME-Version: 1.0 To: KFGlynn@aol.com CC: Low Power Amateur Radio Discussion Subject: Re: Half-Square Antenna References: <960702095949_426048620@emout18.mail.aol.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Hi Kevin and all, The formula for a half square is: Top Leg: 492/FREQ=feet Verticals: 240/FREQ=feet Feed with 50 ohm line, connecting the top leg to the center conductor of the coax, the vertical to the sheild. If you have the 9/94 CQ you have the article by N4PC on this antenna. He loved it. Especially the 21deg take-off angle. I will be QRV on 40M (7.040 +/-) from Rushford, NY, Allegany County, from Wed evening thru Friday eve. Rig will be MFJ 9040, antenna a half square. Hope to work a few QRP-listers and maybe a few county hunters! -- 72's de Mark, N2VPK, Member of the Buffalo QRP Connection TMPS 1996 Q's=117 WAS=27 Confirmed=05 DX=17 HW-9 @ 3W, MFJ941C, 142' Sloping Delta Loop 6W1 C6 CT3 DL EA ES HC LY LZ OM OZ SM U5 VE XE YT ZF Worked all Canada= VE1 VO1 VA2 VE2 VA3 VY2 VE6 From na5k@juno.com Tue Jul 2 16:08:07 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <175075-51527>; Tue, 2 Jul 1996 12:07:58 -0400 Received: from x5.boston.juno.com (x5.boston.juno.com [205.231.100.23]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id MAA151537 for ; Tue, 2 Jul 1996 12:07:49 -0400 Received: (from na5k@juno.com) by x5.boston.juno.com (queuemail) id MAA21759; Tue, 02 Jul 1996 12:06:22 EDT To: qrp-l@Lehigh.EDU Date: Tue, 2 Jul 1996 10:58:18 PST Subject: Re: Half-Square Antenna Message-ID: <19960702.110425.9638.2.na5k@juno.com> References: <960702095949_426048620@emout18.mail.aol.com> X-Mailer: Juno 1.00 X-Juno-Line-Breaks: 0-3,5,7,9-11,14-15,18-20,22,24,26-28,33-37 From: na5k@juno.com (Smitty Smith) On Tue, 2 Jul 1996 09:59:49 -0400 KFGlynn@aol.com writes: >Hi Gang, > >In a recent QRPp the half-square antenna was discussed. (Can't locate the >issue at the moment...) Does anyone have any experience with this antenna? > It sounds like the perfect thing to complement my delta loop for portable >field operation. I had good success with a Half Square antenna cut for 80 meters at my home station. It was fed at the bottom of one of the vertical legs. It also worked great on 40 and 30 meters. Seems like it would be a good camping antenna, 1/2 half wave accross the top and 1/4 wave dangling down at the ends. For 40 meters, find two trees that are at least 33 ft high and 66 feet apart. > >Looking for formulas for horizontal wire and two legs. Also wondering if I >brought the feedline off at a 45 degree angle vs. right angles, how would >that affect the radiation pattern. May be a bit difficult to bring it off at >right angles. Don't know about this, however, you can feed it at the bottom of one of the legs. The impedance might require that you use 300 ohm or 450 ohm feed line and a tuner, but I wonder if you could just camp under the tree and feed one of the vertical sections directly into a tuner. Remember, with a tuner, it will work on other bands. CUL, Smitty, NA5K From ac6ls@amsat.org Tue Jul 2 16:42:22 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174964-18245>; Tue, 2 Jul 1996 12:41:35 -0400 Received: from cylynk.cyberlynk.com (cyberlynk.com [206.54.59.2]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with SMTP id MAA124327 for ; Tue, 2 Jul 1996 12:28:45 -0400 Received: from philp@cyberlynk.com.cyberlynk.com (ppp39mer.cyberlynk.com [206.54.59.39]) by cylynk.cyberlynk.com (8.6.12/8.6.9) with SMTP id JAA21065; Tue, 2 Jul 1996 09:26:44 -0700 Message-ID: <31D94E1B.7509@amsat.org> Date: Tue, 02 Jul 1996 09:28:11 -0700 From: "Phil, AC6LS" X-Mailer: Mozilla 3.0b4Gold (Win95; I) MIME-Version: 1.0 To: KFGlynn@aol.com CC: qrp-l@Lehigh.EDU Subject: Re: Half-Square Antenna References: <960702095949_426048620@emout18.mail.aol.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit KFGlynn@aol.com wrote: > > In a recent QRPp the half-square antenna was discussed. (Can't locate the > issue at the moment...) here is the formula for the Half Square: -492/f- --------------------------------------------------0 | 0 feed pnt. | | | | | | 240/f | | 240/f | | | | | | | | the left leg is physicaly attached to the horizontal element. the horizontal element is the positive feedpoint, which should be feed with coax , and the right leg would be where you attach the coax shield. I have read some reports of "nesting" several different wavelength antennas together on the same feed point and also using twinlead and a tuner for multibanded operation. several places had info on this ant. Hambrew, QRPp, the Antennas West catalog just to name a few. I have a 20 and 40m version. The 20m version I have used with good results, the 40m has yet to see some action. (size is a factor.) 72, de Phil AC6LS From cebik@utkux.utcc.utk.edu Tue Jul 2 20:55:48 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174169-35400>; Tue, 2 Jul 1996 16:55:29 -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 QAA48043 for ; Tue, 2 Jul 1996 16:55:14 -0400 Received: by utkux4.utcc.utk.edu (SMI-8.6/2.7c-UTK) id QAA00457; Tue, 2 Jul 1996 16:54:45 -0400 Date: Tue, 2 Jul 1996 16:54:44 -0400 (EDT) From: "L. B. Cebik" X-Sender: cebik@utkux4.utcc.utk.edu To: KFGlynn@aol.com cc: qrp-l@Lehigh.EDU Subject: Re: Half-Square Antenna In-Reply-To: <960701101722_146601615@emout13.mail.aol.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Kevin, A half-square antenna consists of (roughly) two quarter-wave length vertical sections about a half wavelength apart and connected by a wire at the top. If one has a primary interest in a single band, then it is fed at one of the two upper corners and can present something close to 50-ohms impedance for direct coax feeding. Yhe advantage claimed for the half square is that it presents a mostly vertically polarized field, with a low take-off angle, without a radial system. The verticals can be fairly close to the ground. I modeled a 40 meter version. The vertical sections are 35' long, going from a height of 5' up to 40'. The half-wave section is 69.2' long. This seemed to maximize the vertical field, although I may not have gotten it to the absolute max. The input Z at the upper corner was resonant at about 60-ohms, and the impedance drops if the whole system is raised a bit. If the antenna runs from 35' to 70' at the top, the impedance drops to about 40 ohms. The pattern is a peanut, with the max gain perpendicular to the horizontal wire. It is a more radical peanut than the oval patterns I described in the notes on the delta loop, and the max gain is about 3.1 dBi--more than that of the delta loop (which is to be expected from a pattern that is more radically pinched). The angle of max radiation with the bottom of the vertical wires 5' off the ground is 21 degrees, similar to that of the delta loop. The model was of #14 copper wire over medium earth using Sommerfeld-Norton grounds on NEC-2. You can work out variations for other wire sizes and minimum heights. However, if you change the proportions of the vertical and horizontal sections, you will change the proportion of vertically polarized radiation. The result may be too much horizontally polarized radiation, which is mostly high-angle stuff. Keeping the proportions in the rough ballpark noted here will keep the antenna mostly vertically polarized for better dx signal to noise ratios. Feeding the antenna with 450-ohm line is feasible with an ATU. If fed at the same point, there will be no difference in 40 meter performance. I have not looked at the patterns and impedances for other bands. Feed the antenna at right angles to the wires for a significant distance. This means bringing the feedline from the upper corner horizontally away from the junction in a direction perpendicular to both the vertical and horizontal wires. A gentle slope of the feedline toward the ground should cause no problems. Good luck with the antenna. -73- LB, W4RNL From k3tks@u1.abs.net Thu Aug 22 12:22:25 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <174153-53272>; Thu, 22 Aug 1996 08:22:18 -0400 Received: from abs.net (k3tks@[207.114.0.130]) by nss2.CC.Lehigh.EDU (8.7.5/8.7.3) with ESMTP id IAA34351 for ; Thu, 22 Aug 1996 08:22:03 -0400 Received: from localhost (k3tks@localhost) by abs.net (8.7.4/8.7.3) with SMTP id IAA03747; Thu, 22 Aug 1996 08:21:55 -0400 (EDT) Date: Thu, 22 Aug 1996 08:21:55 -0400 (EDT) From: George Gingell To: DLShips@aol.com cc: W3RDF@aol.com, QRP List , Maryland Milliwatt Club -- Paul Stroud , Chuck Adams , "Gil KosT (The American QRP Key Mfg Co.)" , Ben Schultz , Bob White , "Craig J. Sterling" , Dave Johnson , "Don (Kite Beacon) Shipman" , Scott Rosenfeld , Randy Milliwatt Webmaster Berry , k3tks@u1.abs.net, John Foote , n2cx@voicenet.com, Niel Skousen , Niel Skousen , Pete Rossi , Bruce Muscolino , Mike Czuhajewski , Walt Thomas , "Jerry (MRC) Johnson" Subject: Re: Antenna comparisons In-Reply-To: <960821231058_462543140@emout07.mail.aol.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Thanks for the comments, I will pass them along to qrp-l for you. I am sure there will be others interested in hearing about some actual antenna comparisons. I don't know much about the theory, I just look em up in the book and build em.:^) What ever it takes. So far, my money is on the loop. I have a 40 meter vertical loop, aka Doug DeMaw "Classic Loop" the Rectangle that is about 35-40 feet off the ground at the top. I think the sides ar about 26 feet and the bottom is 10-12 feet off the ground. It is fed with RG8X and a Q section of RG11. It is one of the most reliable antennas that I have ever built. The other loop that I have is the 80 Meter horizontal A.O.G. ("Act of GOD") Loop at 45 feet and fed with Rg-59 Equiv. Computer LAN Cable.. I have a few Dipoles left over from the previous antenna farm. I think I counted 9 Coax Cables going out the RF pipe last week. :^) A few no longer have anything on the end of them. I replaced three with fresh coax for the Fall Antenna Party. :^) TKS again for the comments Don. I will be looking forward to hearing more about your Kites and Antennas. QRP DX TU (C) 1986 G.Danny Gingell, K3TKS@.abs.net On Wed, 21 Aug 1996 DLShips@aol.com wrote: > Dan, > > This may be of some interest to some of the guys....if you think so, feel > free to pass it along. I still haven't re connected to the QRP-L (List) but > intend to do so when I get back from a trip I'm taking (starting) tomorrow. > > Here's some antenna comparison info. > > I've been using a ground mounted, quarter wave vertical on 30 meters and > cosistantly work into Europe (when the band is open) with a couple of watts. > I'm in a very good radio location, two blocks off the beach. There's 8 > radials at the base of the vertical and the soil is sandy and damp and I have > an 8 ft. ground rod connected to the base. Impedence at the base of the > vertical is 47ohms and I'm feeding it with 1/2 wave of coax. > > The storm removed a 20 meter square loop I had between two pine trees so I > replaced it with a 30 meter loop, perfectly square and vertical, fed in a > lower corner with 450 ohm ladder line. This loop is 25 ft. on all sides and > is about 12 ft. above the ground at the bottom and 37 ft. at the top. It's > broadside to N. & S. > > My station is set up with switching capabilities that allow me to quickly > switch between 6 radios and 8 antennas, so I frequently compare the same > signals on differnet antennas. I have two quarter wave 40 meter verticals (a > quarter wave apart but not yet used together) , a pair of (90 degree phased) > 20 meter verticals, a 20 meter half square (oriented such to compare with the > 20 meter verticals), a long wire, and finally a 160 meter center fed low > flying wire (max hight is 25 ft above the ground. And a couple other antennas > that serve my test bench > > In comparing the 30 meter vertical with the loop, the loop comes out the > winner most of the time. It's no surprise to me. In many cases it's a good > couple of s-units. A couple of days ago I asked a German station to compare > the signal from each antenna and although he couldn't tell much difference, I > could hear him much better with the loop. I'm not ready to abandon the > vertical yet, but I once had a coax dipole in the place now occupied by the > loop and I was quite impressed with its performance. It was my best 30 meter > antenna at the time but I didn't run any serious comparison tests on it. > > I compared the 20 meter phased verticals with the 20 meter half square and > the half square seems to win most of the time (with signals broadside to the > half square and in line with the verticals) With signals broadside to the > verticals and at the end of the half square, there's a tiny difference in > favor of the verticals. This week I moved the verticals to the roof of my > shack (a 16' X 12' building in my back yard). Basically I changed them into > phased ground planes, each with four radials. I did this in an effort to get > the feed point impedence to look exactly alike on each pole, and to reduce > the ground loss. I was surprised at how little difference it made.. > > The bottom line is that it's hard to beat the simple half square antenna. I'm > not ready to throw in the towel with the verticals yet but I have brought > them back to ground level now. > > Should I decide to put the aluminum away, I may go back to a bobtail curtain > which I lost during one of the coastal storms, and begin to compare the > bobtail with the half square... By the way, the bottom of the vertical wires > of the half square are about 12 ft. off the ground..... > > Hope this starts you thinking of a new antenna...tee hee..... > > 72's ...de W3RDF, Don in North Myrtle Beach. > > > > From kd0fx@worldnet.att.net Sun Nov 3 20:07:04 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34835-42147>; Sun, 3 Nov 1996 15:07:02 -0500 Received: from mtigwc01.worldnet.att.net (ns.worldnet.att.net [204.127.129.1]) by nss2.CC.Lehigh.EDU (8.8.2/8.8.2) with ESMTP id PAA159987 for ; Sun, 3 Nov 1996 15:06:58 -0500 Received: from grope-s ([207.147.131.72]) by mtigwc01.worldnet.att.net (post.office MTA v2.0 0613 ) with SMTP id AAA12506 for ; Sun, 3 Nov 1996 20:06:08 +0000 Message-Id: <1.5.4.32.19961103200440.006649fc@postoffice.worldnet.att.net> X-Sender: kd0fx@postoffice.worldnet.att.net X-Mailer: Windows Eudora Light Version 1.5.4 (32) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Sun, 03 Nov 1996 12:04:40 -0800 To: qrp-l@Lehigh.EDU From: Mike Boice Subject: Bobtail Curtain/Half Square Question I'm contemplating building one of these (I believe they're the same design) cut for 18.096 MHz. I calculate the 1/2 wave top "leg" to be 27.2 ft, while each vertical leg to be 12.9 feet. I can accomodate both of these dimensions, just not "together." What I mean is, I have two wooden posts, one around 13 feet tall, one around 15 feet tall, on opposite sides of my house. The distance between these posts is around 55 feet. I can run one vertical leg and the horizontal leg, but the remaining vertical leg would end up laying on the roof (only a couple feet below). While I assume this would probably fall into the "effective" category (as related in recent postings), I'm wondering if there is a better way around this, or possibly an alternative antenna design for 17 meters that would better use this space (vertically &/or horizontally). I'm thinking that I might actually be able to get some type of "gain" antenna up (albeit relatively low to the ground) for this band, since the wavelengths are so short. Also, what is the rough feedpoint impedance of a bobtail curtain if properly hung? Oh yeah - what the heck is a Sterba Curtain? I've seen several references to it over the past few months, but I can't seem to find mention of it in my ARRL Antenna Handbook (circa 1976) or regular Handbook (1982 edition - yeah, I know it's time to get a little more up to date, but Christmas isn't here yet). Many thanks to all out there in "The Land of a Thousand Elmers." 73, mike KD0FX Richland WA QRP-L #576 QRP ARCI #9270 From stan@cruzio.com Tue Nov 5 07:35:25 1996 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34932-24059>; Tue, 5 Nov 1996 02:35:22 -0500 Received: from cruzio.com (mmdf@bbs.cruzio.com [165.227.10.31]) by nss2.CC.Lehigh.EDU (8.8.2/8.8.2) with SMTP id CAA214192 for ; Tue, 5 Nov 1996 02:35:17 -0500 Received: from surf82.cruzio.com by cruzio.com id aa11290; 4 Nov 96 23:33 PST Message-ID: <327EED70.50@cruzio.com> Date: Mon, 04 Nov 1996 23:32:00 -0800 From: Stan Goldstein X-Mailer: Mozilla 2.02Gold (Win95; I) MIME-Version: 1.0 To: kd0fx@worldnet.att.net CC: Low Power Amateur Radio Discussion Subject: Re: Bobtail Curtain/Half Square Question References: <1.5.4.32.19961103200440.006649fc@postoffice.worldnet.att.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Mike Boice wrote: > > I'm contemplating building one of these (I believe they're the same design) > cut for 18.096 MHz. >.... but the remaining vertical leg would > end up laying on the roof (only a couple feet below). While I assume this > would probably fall into the "effective" category (as related in recent > postings), I'm wondering if there is a better way around this, or possibly > an alternative antenna design for 17 meters that would better use this space > (vertically &/or horizontally). I'm thinking that I might actually be able > to get some type of "gain" antenna up (albeit relatively low to the ground) > for this band, since the wavelengths are so short. Hi Mike, As I recall the way a bobtail works is like 2 phased verticals . Bending one just a few feet down would probably alter the way the antenna works. Effective ? Try building or modeling it. If you can bring the vertical leg down, but at an angle, and you do the same thing with the other leg ( keeping them parallel ) , it sould work. > > Also, what is the rough feedpoint impedance of a bobtail curtain if properly > hung? The impedence , if fed form the bottom is very high, similiar to a half- wave vertical m in the order of several thousand ohms. I have seen top feed info that suggests the impedance can be made very close to 50 ohms. I think QST had an article on a "dual-bander " for 12/17 I think. Seems like it was about 2 years ago. I had one up for 80 m , for a while and it performed ok, about equal or perhaps a tad better in its favored direction when compared to a dipole @ 60 feet. 72.5 Stan , N6ULU