From owner-qrp-l@Lehigh.EDU Fri Mar 14 15:10:16 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id PAA17156 for ; Fri, 14 Mar 1997 15:10:14 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id PAA17156 for ; Fri, 14 Mar 1997 15:10:14 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35256-49526>; Fri, 14 Mar 1997 15:09:47 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34874-49526>; Fri, 14 Mar 1997 15:08:51 -0500 Received: from kodakr.kodak.com (kodakr.kodak.com [150.220.251.69]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with SMTP id PAA62549 for ; Fri, 14 Mar 1997 15:08:46 -0500 Received: from iiatasun.cba.kodak.com by kodakr.kodak.com with SMTP id AA19305 (5.67b/IDA-1.5 for ); Fri, 14 Mar 1997 10:51:18 -0500 Received: from brad.pixel.kodak.com ([129.126.122.34]) by iiatasun.cba.Kodak.COM (4.1/SMI-4.1 IIATASUN) id AA27996; Fri, 14 Mar 97 15:52:15 GMT Message-Id: <332A4667.6E7C@kodak.com> Date: Fri, 14 Mar 1997 22:49:11 -0800 Reply-To: bmitchel@kodak.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Bradley S. Mitchell" To: "Low Power Amateur Radio Discussion" Subject: Backpacking Antennas Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.01 (Win95; I; 16bit) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Any great ideas out there for backpacking antennas? For 80/40 meters, I think that an rg-174-U coax fed dipole would probably be fine, but are there any other nifty light weight ideas out there that we might be able to take advantage of? Previously as De-Maw stated in his qrp notebook, I have used the RG-174U with magnet wire, and buttons for insulators. This works great. What other ideas are out there? 73 Brad WB8YGG From owner-qrp-l@Lehigh.EDU Fri Mar 14 20:07:42 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id UAA11479 for ; Fri, 14 Mar 1997 20:07:41 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id UAA11479 for ; Fri, 14 Mar 1997 20:07:41 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35425-49526>; Fri, 14 Mar 1997 20:07:19 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35301-50035>; Fri, 14 Mar 1997 20:06:26 -0500 Received: from x9.boston.juno.com (x9.boston.juno.com [205.231.100.25]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id UAA57054 for ; Fri, 14 Mar 1997 20:06:21 -0500 Received: (from w77kxb@juno.com) by x9.boston.juno.com (queuemail) id U\A06228; Fri, 14 Mar 1997 20:05:16 EST Message-Id: <19970314.175453.8671.3.w77kxb@juno.com> Date: Fri, 14 Mar 1997 20:05:16 EST Reply-To: w77kxb@juno.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: w77kxb@juno.com (William Harris) To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas References: <332A4667.6E7C@kodak.com> X-To: bmitchel@kodak.com X-Cc: qrp-l@Lehigh.EDU X-Mailer: Juno 1.15 X-Juno-Line-Breaks: 0-2,4-20 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO How about an end fed wire against a counterpoise? Works great for me. Bill, W7KXB said that. On Fri, 14 Mar 1997 22:49:11 -0800 "Bradley S. Mitchell" writes: >Any great ideas out there for backpacking >antennas? > For 80/40 meters, I think that an rg-174-U >coax fed dipole would probably be fine, but are there any other >nifty light weight ideas out there that we might be able to >take advantage of? > > Previously as De-Maw stated in his qrp notebook, I have >used the RG-174U with magnet wire, and buttons for insulators. > >This works great. What other ideas are out there? > > > 73 Brad WB8YGG > > From owner-qrp-l@Lehigh.EDU Fri Mar 14 22:23:38 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id WAA15029 for ; Fri, 14 Mar 1997 22:23:37 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id WAA15029 for ; Fri, 14 Mar 1997 22:23:37 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35646-49526>; Fri, 14 Mar 1997 22:23:25 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35627-20853>; Fri, 14 Mar 1997 22:22:27 -0500 Received: from mail3.voicenet.com (mail3.voicenet.com [207.103.0.45]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id WAA42098 for ; Fri, 14 Mar 1997 22:22:19 -0500 Received: from cherryhill130.voicenet.com (cherryhill130.voicenet.com [207.103.11.209]) by mail3.voicenet.com (8.7.5/8.6.12) with SMTP id WAA27030; Fri, 14 Mar 1997 22:26:12 -0500 (EST) Message-Id: <199703150326.WAA27030@mail3.voicenet.com> Date: Fri, 14 Mar 1997 22:26:12 -0500 (EST) Reply-To: n2cx@voicenet.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Joe Everhart To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-To: bmitchel@kodak.com X-Cc: qrp-l@Lehigh.EDU X-Sender: n2cx@voicenet.com X-Mailer: Windows Eudora Light Version 1.5.2 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Brad, You queried about ideas for backpacking antennas. I am, of course rather partial to lightweight dipoles fed with small coax (like the PVC Gusher-II), but lately I've been focussing on another option. An end-fed half-wave antenna is even lighter than the dipole becasue it has no long coax feedline. You do need a tuner and a counterpoise, though they can be simple. The tuner can be a vary simple one like the Rainbow. and the counterpoise can be a very unsophisticated 1/4 wave wire. The Rainbow pc board weighs less than 2 oz and even when mounted in an Altoids tin, with a 12 volt lighter battery comes in at about 4 oz. The small diameter hookup wire and pvc pipe section insulators wire tip the scales at under a half pound and fit in a small zip-lock bag. For 40 or 80, the wire can be as efficient as a dipole when erected as an inveted vee or even better, a sloper. Check the next issue (April but no April fool!) of the NEQRP newsletter 72 for an article on the EFHWA (End Fed Half Wave Antenna). And you will *hear* one in QRP To The Field! 72/73, Joe E., N2CX from Southern New Jersey, y'all work: jeverhart@cayman.vf.mmc.com home: n2cx@voicenet.com From owner-qrp-l@Lehigh.EDU Sat Mar 15 00:13:21 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id AAA18082 for ; Sat, 15 Mar 1997 00:13:20 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id AAA18082 for ; Sat, 15 Mar 1997 00:13:20 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35407-39277>; Sat, 15 Mar 1997 00:13:08 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34914-32880>; Sat, 15 Mar 1997 00:10:46 -0500 Received: from marceau.fm.intel.com (marceau.fm.intel.com [132.233.247.8]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id AAA38182 for ; Sat, 15 Mar 1997 00:10:15 -0500 Received: from fmmail.fm.intel.com by marceau.fm.intel.com (8.8.4/10.0i); Sat, 15 Mar 1997 05:10:08 GMT Received: (from ccmgate@localhost) by fmmail.fm.intel.com (8.8.5/8.7.3) id VAA24791 for qrp-l@lehigh.edu; Fri, 14 Mar 1997 21:12:05 -0800 (PST) Received: by ccm.fm.intel.com (ccmgate 3.2 #2) Fri, 14 Mar 97 21:12:05 PST Date: Fri, 14 Mar 97 22:03:00 PST Reply-To: Cecil_A_Moore@ccm.ch.intel.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Cecil A Moore To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Message-Id: <97Mar15.001308est.35407-39277+5@fidoii.cc.lehigh.edu> Status: RO >From: "Bradley S. Mitchell" >Any great ideas out there for backpacking >antennas? 73 Brad WB8YGG Hi Brad, here is what I consider a great idea for backpack antennas. 102 ft dipole with whatever length of 300 ohm ladder-line that you want to carry. It will work for any HF band but should be tuned ahead of time. For any HF band, there is a place on the ladder-line close to the antenna that will result in a 1:1 SWR when a parallel capacitor is added. There is a second place close to the transmitter that will result in a 6:1 SWR when a parallel capacitor is added. Why would one want to do that? Because a 6:1 SWR will transform the 300 ohms to a perfectly resistive 50 ohms. Put a 1:1 current balun/choke between the ladder- line and the coax and one has a perfectly matched antenna. It's called the double stub matching technique. Is anybody interested in the details? 73, Cecil, W6RCA, OOTC From owner-qrp-l@Lehigh.EDU Sat Mar 15 10:19:15 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id KAA13034 for ; Sat, 15 Mar 1997 10:19:14 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id KAA13034 for ; Sat, 15 Mar 1997 10:19:14 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35462-32880>; Sat, 15 Mar 1997 10:19:01 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35388-35951>; Sat, 15 Mar 1997 10:17:19 -0500 Received: from boris.actnet.net (boris.WEBACCESS.NET [204.251.161.12]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id KAA72306 for ; Sat, 15 Mar 1997 10:17:12 -0500 Received: from SG2939B.webaccess.net ([204.163.168.77]) by boris.actnet.net (post.office MTA v2.0 0813 ID# 0-16334) with SMTP id AAA153; Sat, 15 Mar 1997 08:13:36 -0700 Message-Id: <332ABCE9.3A29@webaccess.net> Date: Sat, 15 Mar 1997 08:14:49 -0700 Reply-To: N0TU@webaccess.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Steve/n0tu To: "Low Power Amateur Radio Discussion" Subject: Impared Antenna Knowledge /Questions References: <97Mar15.001300est.35400-32880+4@fidoii.cc.lehigh.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: "\"Low Power Amateur Radio Discussion\"" , Cecil_A_Moore@ccm.ch.intel.com X-Mailer: Mozilla 3.01 (Win95; I) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Cecil A Moore wrote: > > >From: "Bradley S. Mitchell" > >Any great ideas out there for backpacking > >antennas? 73 Brad WB8YGG > > Hi Brad, here is what I consider a great idea for backpack > antennas. 102 ft dipole with whatever length of 300 ohm > ladder-line that you want to carry. It will work for any > HF band but should be tuned ahead of time. > > For any HF band, there is a place on the ladder-line close > to the antenna that will result in a 1:1 SWR when a parallel > capacitor is added. There is a second place close to the > transmitter that will result in a 6:1 SWR when a parallel > capacitor is added. Why would one want to do that? Because > a 6:1 SWR will transform the 300 ohms to a perfectly resistive > 50 ohms. Put a 1:1 current balun/choke between the ladder- > line and the coax and one has a perfectly matched antenna. > > It's called the double stub matching technique. Is anybody > interested in the details? > > 73, Cecil, W6RCA, OOTC Hello Cecil...I've read several of your postings on this concept...sounds like a great idea. However, my knowledge about antennas is impared as you can see from the questions I ask below! 1. I like the idea of using 300 ohm twinlead because it's lightweight and easy to handle in and out of the pack...I've been using it with simple CLC tuner w/SWR meter...works great. However, I would love to leave that 30 oz. tuner at home on the bench! Will the 300 ohm feedline (twinlead, non-open wire) work with your idea as opposed to the open wire ladderline (I sure haven't seen much of this stuff around lately with all the cable/satellite systems going in)? 2.Does it matter how long or short ur 50 ohm coax is...say you used only a 5' piece of coax? and 40'or so of twinlead? How do determine the where the cap goes and won't it change with frequency and the environmental surroundings. 3.What is a 1:1 current balun/choke? 4.Is this configuration similar to the G5RV? 5.Finally, I usually only operate one band/one rig during an outing so this concept is very appealing...If I understand your idea it's as follows: < 102' wire > ---------------------------- ---------------------------------- || || || < 300 ohm twinlead (?)length || \\ // \\ / \ / \ -||- cap accross feedline \ / at the magic spot? || \\ \\ 50 ohm coax any length? choke balun? +=========================== rig Thank for more details please...Steve ------------------------------------------------------------------ "Just doing it" - Havin'a blast buildin'& usin'QRP gear that is... n0tu/hw8/49er/SW40/38s/solar/backpack-mobile... QRP-L # 911 My homepage - http://www.webaccess.net/~S&P ARS# 206 CQC# 394 From owner-qrp-l@Lehigh.EDU Sat Mar 15 10:22:31 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id KAA13136 for ; Sat, 15 Mar 1997 10:22:30 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id KAA13136 for ; Sat, 15 Mar 1997 10:22:30 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35469-39277>; Sat, 15 Mar 1997 10:22:01 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35418-39277>; Sat, 15 Mar 1997 10:21:20 -0500 Received: from darius.concentric.net (darius.concentric.net [207.155.184.79]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id KAA63871 for ; Sat, 15 Mar 1997 10:21:09 -0500 Received: from cliff.cris.com (cliff.cris.com [199.3.12.45]) by darius.concentric.net (8.8.5/(97/03/03 3.23)) id KAA20101; Sat, 15 Mar 1997 10:21:08 -0500 (EST) [1-800-745-2747 The Concentric Network] Received: from Jess (cnc158041.concentric.net [206.173.169.41]) by cliff.cris.com (8.8.5) id KAA19938; Sat, 15 Mar 1997 10:21:06 -0500 (EST) Message-Id: <332ABF4C.74B0@concentric.net> Date: Sat, 15 Mar 1997 08:25:00 -0700 Reply-To: jessqrp@concentric.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Jess Gypin To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas References: <97Mar15.001256est.35399-39277+4@fidoii.cc.lehigh.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.02Gold (Win95; I) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Cecil A Moore wrote: > > >From: "Bradley S. Mitchell" > >Any great ideas out there for backpacking > >antennas? 73 Brad WB8YGG > > Hi Brad, here is what I consider a great idea for backpack > antennas. 102 ft dipole with whatever length of 300 ohm > ladder-line that you want to carry. It will work for any > HF band but should be tuned ahead of time. > > 73, Cecil, W6RCA, OOTC Hi all, I am not a backpacker, but, as Cecil has suggested, I have tried several antennas camping. I currently have only two that I use. I have tried a resonant dipole, a long wire with a counterpoise wire, a half square, ant the two that I now carry. One is the SLV with the "N0TFI coil". This is similar to the mod where you add a PVC coil wound with wire except that the coil is made from foam pipe insulation wrapped with tinned coil wire on hte lower section. I can find a match with a jumper wire on any band from 80-10 meters and it works! With the right coil tap position, the SWR is about 1.2-1 and the Z is about 44 ohms, so I know that it is working. I have worked all over the world with this set up. The other antenna that I would take with me if I could have only one is the one that Cecil suggests above. The location that i hve done most of my antenna testing from "camping" is up at the cabin at the YMCA camp in Estes Park that we go to a couple of time a year. I sring about 100 feet of 18 ga speaker wire fed with 300 ohm twin lead to a QRP tuner. I don't worry about the "matching" with the tuner. This antenna works FB on 80 meters and far and exceeids the dipoles and long wires that I have used. Whether the antenna is 20 feet up or 80 feet up, it hears and works well. Using the small speaker wire and light weight 300 ohm twin lead, the whole thing rolls up in a package that is very small and light, will fit in a baggy and coat pocket. This just aligns right with the old rule of antennas that you just out up as much wire as you can as high in the aire as you can get it and feed it with as low a loss line as possible, get on the aire and have fun! I would say that if you are going single band, take a resonant dipole and leave the tuner at home. If you are going to work multiple bands, get yourself a nice little tuner like Emtechs Z match and take a 100 + foot wire and have fun! Best Jess N0TFI http://www.concentric.net/~jessqrp From owner-qrp-l@Lehigh.EDU Sat Mar 15 11:20:20 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id LAA14624 for ; Sat, 15 Mar 1997 11:20:19 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id LAA14624 for ; Sat, 15 Mar 1997 11:20:19 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35419-35951>; Sat, 15 Mar 1997 11:19:49 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35316-35951>; Sat, 15 Mar 1997 11:18:06 -0500 Received: from ns.newwave.net (ns.newwave.net [204.70.211.98]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id LAA47838 for ; Sat, 15 Mar 1997 11:17:52 -0500 Received: from lizard (pm1s5.newwave.net [206.99.172.55]) by ns.newwave.net (8.8.5/8.8.5/8.7=Jerry) with SMTP id LAA03035; Sat, 15 Mar 1997 11:17:45 -0500 (EST) Message-Id: <332ACC36.15D0@newwave.net> Date: Sat, 15 Mar 1997 11:20:06 -0500 Reply-To: bwalker@newwave.net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Bill Walker To: "Low Power Amateur Radio Discussion" Subject: Re: Impared Antenna Knowledge /Questions References: <97Mar15.001300est.35400-32880+4@fidoii.cc.lehigh.edu> <332ABCE9.3A29@webaccess.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: N0TU@webaccess.net X-Cc: Low Power Amateur Radio Discussion X-Mailer: Mozilla 3.01 (Win16; I) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Steve/n0tu wrote: > > Cecil A Moore wrote: > > > > >From: "Bradley S. Mitchell" > > >Any great ideas out there for backpacking > > >antennas? 73 Brad WB8YGG > > > > Hi Brad, here is what I consider a great idea for backpack > > antennas. 102 ft dipole with whatever length of 300 ohm > > ladder-line that you want to carry. It will work for any > > HF band but should be tuned ahead of time. > > > > For any HF band, there is a place on the ladder-line close > > to the antenna that will result in a 1:1 SWR when a parallel > > capacitor is added. There is a second place close to the > > transmitter that will result in a 6:1 SWR when a parallel > > capacitor is added. Why would one want to do that? Because > > a 6:1 SWR will transform the 300 ohms to a perfectly resistive > > 50 ohms. Put a 1:1 current balun/choke between the ladder- > > line and the coax and one has a perfectly matched antenna. > > > > It's called the double stub matching technique. Is anybody > > interested in the details? > > > > 73, Cecil, W6RCA, OOTC > > Hello Cecil...I've read several of your postings on this > concept...sounds like a great idea. However, my knowledge about antennas > is impared as you can see from the questions I ask below! > > 1. I like the idea of using 300 ohm twinlead because it's lightweight > and easy to handle in and out of the pack...I've been using it with > simple CLC tuner w/SWR meter...works great. However, I would love to > leave that 30 oz. tuner at home on the bench! Will the 300 ohm feedline > (twinlead, non-open wire) work with your idea as opposed to the open > wire ladderline (I sure haven't seen much of this stuff around lately > with all the cable/satellite systems going in)? > > 2.Does it matter how long or short ur 50 ohm coax is...say you used only > a 5' piece of coax? and 40'or so of twinlead? How do determine the where > the cap goes and won't it change with frequency and the environmental > surroundings. > > 3.What is a 1:1 current balun/choke? > > 4.Is this configuration similar to the G5RV? > > 5.Finally, I usually only operate one band/one rig during an outing so > this concept is very appealing...If I understand your idea it's as > follows: > > < 102' wire > > ---------------------------- ---------------------------------- > || > || > || < 300 ohm twinlead (?)length > || > \\ > // > \\ > / \ > / \ > -||- cap accross feedline > \ / at the magic spot? > || > \\ > \\ 50 ohm coax any length? > choke balun? +=========================== rig > > Thank for more details please...Steve > ------------------------------------------------------------------ > "Just doing it" - Havin'a blast buildin'& usin'QRP gear that is... > n0tu/hw8/49er/SW40/38s/solar/backpack-mobile... QRP-L # 911 > My homepage - http://www.webaccess.net/~S&P ARS# 206 CQC# 394 Steve: I wonder if that magic capacitor could be a varibale so the line could be tuned on the fly? Bill NK8Y QRP #4103 From owner-qrp-l@Lehigh.EDU Sat Mar 15 18:38:21 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id SAA03495 for ; Sat, 15 Mar 1997 18:38:20 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id SAA03495 for ; Sat, 15 Mar 1997 18:38:20 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35657-39277>; Sat, 15 Mar 1997 18:38:06 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35651-32880>; Sat, 15 Mar 1997 18:36:47 -0500 Received: from marceau.fm.intel.com (marceau.fm.intel.com [132.233.247.8]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id SAA27780 for ; Sat, 15 Mar 1997 18:36:45 -0500 Received: from fmmail.fm.intel.com by marceau.fm.intel.com (8.8.4/10.0i); Sat, 15 Mar 1997 23:36:38 GMT Received: (from ccmgate@localhost) by fmmail.fm.intel.com (8.8.5/8.7.3) id PAA07975 for qrp-l@lehigh.edu; Sat, 15 Mar 1997 15:39:02 -0800 (PST) Received: by ccm.fm.intel.com (ccmgate 3.2 #2) Sat, 15 Mar 97 15:39:02 PST Date: Sat, 15 Mar 97 16:33:00 PST Reply-To: Cecil_A_Moore@ccm.ch.intel.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Cecil A Moore To: "Low Power Amateur Radio Discussion" Subject: Backpacking Antennas (and others) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Message-Id: <97Mar15.183806est.35657-39277+159@fidoii.cc.lehigh.edu> Status: RO This thread will describe a method of matching an antenna using one parallel capacitor. I'll describe the two capacitor method later. Let's take the easier one first which requires a certain total length of twinlead or ladder-line for each frequency. Let's concentrate on 300 ohm ladder-line with a velocity factor of 0.8 feeding a 102 ft center-fed dipole on 7.045 MHz. I have already published a BASIC program which allows one to estimate the location of the Imax (current loop) point on the feedline. If the 300 ohm SWR is greater than 6:1, we will be able to find a PC-50 point where a Parallel Capacitor will result in a perfectly resistive 50 ohms on one frequency. On each side of this resonant frequency, the antenna will act similar to a resonant dipole with rising SWRs. However, by varying the length of the ladder-line by a few feet, a 1:1 SWR can be achieved across the entire band. Lets look at our 102 ft dipole on 7.045 MHz. EZNEC says that the SWR of our 40 ft tall antenna is 10.6:1 so we are satisfied that we will be able to achieve our 50 ohm target. (300 divided by 10.6 is less than 50). The following statements apply to all frequencies. The fartherest away from the Imax point that the PC-50 point ever gets is 0.014 wavelength. For 300 ohm line with VF equal 0.8, dividing 787 by the frequency will give us one wavelength of ladder-line. The maximum value of capacitive reactance ever required is -j55 ohms. Our frequency is 7.045 MHz. 787/7.045 = 111.7 ft equals one wavelength. 0.014 times 111.7 equals 1.6 ft. Our BASIC program says that an Imax point exists at 35.6 ft. 35.6 + 1.6 = 37.2 ft. -j55 ohms at 7.045 MHz is about 400 pf so let's use a 1000pf variable capacitor. We need to feed this arrangement with a 1:1 current choke/balun. A number of turns of coax or a W2DU toroidal sleeve choke or a number of turns of coax on a toroid will work. We can use a 50 ohm antenna analyzer or the rig and an SWR meter for fine tuning. While varying the frequency and capacitor, we can find a resonant frequency. It is probably lower than 7.045 MHz. If it is, the feedline is too long so cut off six inches and try again. Keep it up until the antenna yields a 50 ohm SWR of 1:1 on 7.045 MHz. If the resonant frequency is too high, the feedline will need to be lengthened. Butt connectors are ideal for splicing ladder-line. Explaining something like this is extremely difficult without graphics. When we are finished, our antenna system should look something like this. +---------+ | 1:1 |---+------------------------------------- XMTR-| Current | 400pf cap about 33.4 ft twinlead to ant | Balun |---+------------------------------------- +---------+ If 33.4 ft is too short, simply add 1/2 wavelength of ladder-line. If it's not obvious, the 400pf capacitor *is* our balanced antenna tuner. Note that the 33.4 ft of twinlead is close to the length of the "tuned feeder" on a G5RV. This can be done for any length center-fed antenna on any frequency provided the 300 ohm SWR is greater than 6:1. (300/SWR < 50) 73, Cecil, W6RCA, OOTC From owner-qrp-l@Lehigh.EDU Sat Mar 15 20:00:51 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id UAA05988 for ; Sat, 15 Mar 1997 20:00:50 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id UAA05988 for ; Sat, 15 Mar 1997 20:00:50 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35136-35951>; Sat, 15 Mar 1997 20:00:37 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35024-39277>; Sat, 15 Mar 1997 19:59:39 -0500 Received: from x9.boston.juno.com (x9.boston.juno.com [205.231.100.25]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id TAA63434 for ; Sat, 15 Mar 1997 19:59:33 -0500 Received: (from w77kxb@juno.com) by x9.boston.juno.com (queuemail) id TQE29221; Sat, 15 Mar 1997 19:59:10 EST Message-Id: <19970315.174914.4831.1.w77kxb@juno.com> Date: Sat, 15 Mar 1997 19:59:10 EST Reply-To: w77kxb@juno.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: w77kxb@juno.com (William Harris) To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas References: <199703150326.WAA27030@mail3.voicenet.com> X-To: n2cx@voicenet.com X-Cc: qrp-l@Lehigh.EDU X-Mailer: Juno 1.15 X-Juno-Line-Breaks: 4-8,10-53 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Brad: Regarding my remarks about an end fed wire, make it an odd 1/4 wl. for the band of operation. In fact, a few degrees longer will bring you up to the 50 ohm feed point with some inductive reactance which you could tune out with a small air variable condenser of about 250 mmfd. If you can live with the vswr, forget the condenser. Bill W7KXB Mesa, Az. On Fri, 14 Mar 1997 22:26:12 -0500 (EST) Joe Everhart writes: >Brad, > >You queried about ideas for backpacking antennas. I am, of >course rather partial to lightweight dipoles fed with small >coax (like the PVC Gusher-II), but lately I've been focussing >on another option. > >An end-fed half-wave antenna is even lighter than the dipole >becasue it has no long coax feedline. You do need a tuner and >a counterpoise, though they can be simple. The tuner can be a >vary simple one like the Rainbow. and the counterpoise can be >a very unsophisticated 1/4 wave wire. > >The Rainbow pc board weighs less than 2 oz and even when >mounted in an Altoids tin, with a 12 volt lighter battery >comes in at about 4 oz. The small diameter hookup wire and >pvc pipe section insulators wire tip the scales at under a >half pound and fit in a small zip-lock bag. > >For 40 or 80, the wire can be as efficient as a dipole when >erected as an inveted vee or even better, a sloper. > >Check the next issue (April but no April fool!) of the NEQRP >newsletter 72 for an article on the EFHWA (End Fed Half Wave >Antenna). > >And you will *hear* one in QRP To The Field! > > > >72/73, > >Joe E., N2CX > >from Southern New Jersey, y'all > >work: jeverhart@cayman.vf.mmc.com >home: n2cx@voicenet.com > > > > > From owner-qrp-l@Lehigh.EDU Sat Mar 15 21:27:41 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id VAA09283 for ; Sat, 15 Mar 1997 21:27:39 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id VAA09283 for ; Sat, 15 Mar 1997 21:27:39 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35527-39277>; Sat, 15 Mar 1997 21:27:27 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34859-32880>; Sat, 15 Mar 1997 21:26:28 -0500 Received: from postal.atlanta.net (postal.atlanta.net [155.229.2.2]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id VAA63248 for ; Sat, 15 Mar 1997 21:26:24 -0500 Received: from LOCALNAME (venus16.atlanta.com [155.229.56.32]) by postal.atlanta.net (8.8.5/8.8.0) with SMTP id VAA03733 for ; Sat, 15 Mar 1997 21:26:22 -0500 (EST) Message-Id: <332B9282.1464@atlanta.com> Date: Sat, 15 Mar 1997 22:26:10 -0800 Reply-To: rbe@atlanta.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Bob Edwards, W4ED" To: "Low Power Amateur Radio Discussion" Subject: Backpacking Antennas MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailer: Mozilla 2.02E-KIT (Win16; U) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO To those interested in such antlers, and have not looked at the 40m/20m wire vertical on the TRF page, here is its WWW address: http://members.aol.com/aa7qu/tfridx.html Look at entry #2, the last half. This antenna does not need a tuner, but it does use a 300 ohm Q-section on 20m. -- /| Bob 72/73 / | | / |\ /| / E | \ W4ED x_AE4CA nr Atlanta @EM73wt /_|/____|__\_ ...."QRP", more from less.... [\--======-/ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ From owner-qrp-l@Lehigh.EDU Sat Mar 15 23:18:02 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id XAA12089 for ; Sat, 15 Mar 1997 23:18:00 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id XAA12089 for ; Sat, 15 Mar 1997 23:18:00 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35715-39277>; Sat, 15 Mar 1997 23:17:53 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35644-32880>; Sat, 15 Mar 1997 23:16:42 -0500 Received: from mail3.voicenet.com (mail3.voicenet.com [207.103.0.45]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id XAA47645 for ; Sat, 15 Mar 1997 23:16:38 -0500 Received: from cherryhill130.voicenet.com (cherryhill130.voicenet.com [207.103.11.209]) by mail3.voicenet.com (8.7.5/8.6.12) with SMTP id XAA04744; Sat, 15 Mar 1997 23:20:28 -0500 (EST) Message-Id: <199703160420.XAA04744@mail3.voicenet.com> Date: Sat, 15 Mar 1997 23:20:28 -0500 (EST) Reply-To: n2cx@voicenet.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: Joe Everhart To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-To: w77kxb@juno.com (William Harris) X-Cc: qrp-l@Lehigh.EDU, bmitchel@kodak.com X-Sender: n2cx@voicenet.com X-Mailer: Windows Eudora Light Version 1.5.2 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO At 07:59 PM 3/15/97 EST, you wrote: >Brad: Regarding my remarks about an end fed wire, make it an odd 1/4 wl. >for the band of operation. In fact, a few degrees longer will bring you >up to the 50 ohm feed point with some inductive reactance which you could >tune out with a small air variable condenser of about 250 mmfd. If you >can live with the vswr, forget the condenser. > >Bill W7KXB >Mesa, Az. > Bill and Brad, My preference is for the half wave antenna since it is much more ground-independent that the quarter wave. I agree that it is attractive to match a quarter wave antenna, but the problem is that efficiency can be very poor with the typical simple ground system passible in backpacking situations. The ARRL Antenna book estimates that quarter wave antennas with ground systems on the order of 10 quarter wave radials may be less than 50% (in fact I think they say less than that, but my book isn't handy). Now using a ground system with fewer radials may be proportionately worse! Sure, it may match very well, but most of the power will be wasted! On the other hand, the half-wave antenna uses s counterpoise or simple ground system primarily to decouple the feed system from the antenna. Even with a ground resistance of 50 ohms, loss will be negligible with an end-fed antenna whose radiation resistance is 1000 ohms or more. Plus, with the half-wave wire, radiation takes place high up in the air. With a quarter wave wire, it is right at ground level where it can be absorbved by surrounding objects. Anyway that's how I see it. :-) 72/73, Joe E., N2CX from Southern New Jersey, y'all work: jeverhart@cayman.vf.mmc.com home: n2cx@voicenet.com From owner-qrp-l@Lehigh.EDU Sun Mar 16 02:45:52 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id CAA18034 for ; Sun, 16 Mar 1997 02:45:51 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id CAA18034 for ; Sun, 16 Mar 1997 02:45:51 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35584-40325>; Sun, 16 Mar 1997 02:45:30 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35306-40325>; Sun, 16 Mar 1997 02:44:30 -0500 Received: from ridgecrest.ca.us (root@owens.ridgecrest.ca.us [199.120.150.1]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id CAA38324 for ; Sun, 16 Mar 1997 02:44:25 -0500 Received: from [199.120.150.62] (annex052 [199.120.150.62]) by ridgecrest.ca.us (8.8.5/8.8-custom) with SMTP id XAA03880 for ; Sat, 15 Mar 1997 23:42:02 -0800 (PST) Message-Id: Date: Sat, 15 Mar 1997 23:45:19 -0800 Reply-To: herr@ridgecrest.ca.us Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: herr@ridgecrest.ca.us (Michael Herr) To: "Low Power Amateur Radio Discussion" Subject: Re> Backpacking antenna Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Been reading all the suggestions for a backpacking antenna, so I have to add my two cents in. Well, I enjoy backpacking and haming, but I hate the weight! Every trip I look for what I could have done better, simpler, making one item do the job of two. Anything to reduce the weight, then the hassle, and increase the enjoyment. Over the years I have fooled around with just about everything. I'm sorry folks, but the idea of carring around a SLV on a 50 miler just isn't appealing! I've taken dipoles and long wires, tuners and no tuners. Here is where I have settled to. Dipole, (typically 40 meters), feed with RG-174, no tuner. use 100 pound jacketed parachute cord (this is small stuff, not the 550# line you typically see) for the ends. Small wire, about #26, insulated for the antenna. No end insulators, just tied straight to the cord. I don't take a wrist rocket or a special weight and I'd never throw my leatherman tool into a tree (might not see it again). I use a handy rock, tied to the parachute cord. No supports brought along, just what ever tree, bush, or rock wall available (have used tent poles as a support once tho). The bottom line, it has always worked! 72 Mike WA6ARA From owner-qrp-l@Lehigh.EDU Sun Mar 16 11:55:22 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id LAA13728 for ; Sun, 16 Mar 1997 11:55:19 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id LAA13728 for ; Sun, 16 Mar 1997 11:55:19 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35507-19078>; Sun, 16 Mar 1997 11:54:38 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35165-38531>; Sun, 16 Mar 1997 11:53:43 -0500 Received: from ice.onlinesys.com (root@onlinesys.com [199.45.70.2]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id LAA32721 for ; Sun, 16 Mar 1997 11:53:39 -0500 Received: from default (mp6-137.wwdc.com [207.200.132.137]) by ice.onlinesys.com (8.8.5/8.7.3) with SMTP id LAA03068; Sun, 16 Mar 1997 11:54:16 -0500 (EST) Message-Id: <332C2414.7743@wwdc.com> Date: Sun, 16 Mar 1997 11:47:16 -0500 Reply-To: jbcumming@wwdc.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: VE3JC John To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas References: <332A4667.6E7C@kodak.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-To: bmitchel@kodak.com X-Cc: Low Power Amateur Radio Discussion X-Mailer: Mozilla 2.0 (Win95; I) X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Bradley S. Mitchell wrote: > > Any great ideas out there for backpacking > antennas? I too have been enjoying the discussion regarding backpacking antennas, and thought I would throw in my 2 mW worth .... Choice of backpacking antenna (and rig, for that matter !) varies with personal preferences. For me, multiband capability is important, and ultralight weight is not the primary objective (obviously! since I lug a QRP+ ... the Sierra looks like the way to go...) Anyways, a single band rig/antenna is no fun on a canoe trip if the band closes half an hour before the tent is pitched, and it can be frustrating being stuck on a lower band if a rainy day keeps you huddled in the tent through the daylight hours! My choice for practical, reasonably light weight and versatile mult-band antenna is the "8-Band Backpacker Special" described in June 1994 QST. This is essentially a 20m/40m fan dipole with extensions using alligator clips, to give the desired band from 10 to 80 meters. The author, wb0krx, uses magnet wire and 174/u coax - I have used #28 teflon insulated wire and 25' of 174, with a 10' add-on of rg58. Set-up is extremely simple - get the centre insulator (made of a scrap of plexiglass) as high as possible, tie off the ends of the 40 m dipole into convenient trees with long pieces of small diameter nylon cord (so that when the 80m extensions are clipped on to the 40 m element, they can be held up by the nylon cord). The antenna, all extensions, and the cord all fit in a large zip-loc bag. Height, topography, etc will affect swr, but small (eg 6 inch) extensions can be used for "fine tuning". The Apr/94 article has numerous other tips, and makes good reading (especially when a late winter ice storm makes it look like backpacking and canoeing are a ways off!) 72 & 73, John ********************************************************************* VE3JC - JOHN CUMMING 192 WELLINGTON ST. DELAWARE, ON CANADA, N0L 1E0 From owner-qrp-l@Lehigh.EDU Mon Mar 17 09:13:19 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id JAA07526 for ; Mon, 17 Mar 1997 09:13:18 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id JAA07526 for ; Mon, 17 Mar 1997 09:13:18 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35242-18420>; Mon, 17 Mar 1997 09:13:01 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34889-38389>; Mon, 17 Mar 1997 09:11:40 -0500 Received: from Spacestar.Net (root@Larry.Spacestar.Net [204.220.147.2]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with SMTP id JAA41823 for ; Mon, 17 Mar 1997 09:11:31 -0500 Received: from groucho.spacestar.net by Spacestar.Net (8.6.11/SMI-4.1.R931202) id IAA27791; Mon, 17 Mar 1997 08:11:43 -0600 Message-Id: <199703171411.IAA27791@Spacestar.Net> Date: Mon, 17 Mar 1997 08:10:42 -0600 Reply-To: aplitech@Spacestar.Net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Claton Cadmus" To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas X-To: "Low Power Amateur Radio Discussion" X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1160 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO ---------- : From: Daniel C Winkler : : Incidently, the end fed wire is still a dipole. You have just shifted : its feedpoint rather dramatically toward one end. You need a : "counterpoise" to act as the other leg of the dipole. You simply : CANNOT feed an antenna at its very end- the impedance there : is infinite. You need just a little bit of dog to wag that tail! ooonnnnk! Wrong! You do not need a counterpoise to end feed a half wave dipole. You can easily feed a halfwave wire on it's end, the impedance at that end is a reflection of the "other" end and is usually in the range of a few thousand ohms. Examples are the Zepp and J-pole antennas. There was a fine article in Communication Quarterly some months back that explains the details of J-poles and how they work and how the end feed impedance is calculated and what effects it. Great reading. 73 de Cla KA0GKC From owner-qrp-l@Lehigh.EDU Mon Mar 17 09:28:39 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id JAA08087 for ; Mon, 17 Mar 1997 09:28:37 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id JAA08087 for ; Mon, 17 Mar 1997 09:28:37 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35179-38389>; Mon, 17 Mar 1997 09:28:11 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35068-18420>; Mon, 17 Mar 1997 09:27:18 -0500 Received: from marble (marble.litc.lockheed.com [198.7.15.33]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id JAA39915 for ; Mon, 17 Mar 1997 09:27:08 -0500 Received: from cayman.litc.lockheed.com (cayman.litc.lockheed.com [198.7.12.138]) by marble (8.8.3/8.8.2) with SMTP id HAA11769 for ; Mon, 17 Mar 1997 07:26:38 -0700 (MST) Message-Id: <970317085403.206339d5@cayman.vf.mmc.com> Date: Mon, 17 Mar 1997 8:54:03 -0500 Reply-To: JEVERHART@cayman.vf.mmc.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: JEVERHART@cayman.vf.mmc.com To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas X-To: dwink@juno.com X-Cc: qrp-l@Lehigh.EDU, jeverhart@cayman.vf.mmc.com X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Dan, Yes, I did intend to say "feedpoint" resistance. Blame it on a 5 hour drive (withourt a mobile rig) taking my son back to school! I know that it is a dipole but avoid saying that when discussing an end-fed antenna to avoid confusion. When I say dipole, I normally specify a center-fed dipole which is how radio amateurs normally think of them. And if I say "Zepp", I mean an (N times) half-wave antenna end-fed with open wire line, not the common but mistaken "center-fed zepp" used to describe a center fed dipole with open wire feedline. The Germans did not use two dirigibles to support a center fed antenna (and it wuld have required a third to house the transmitter at the other end of the feedline!) On that subject, you *can* wag the dog without a tail. The Zepp is just such a device. Limited in bandwidth, perhaps, but it does not, in theory require a "tail." On the other hand I always recommend a ground or counterpoise when using a half-wave end-fed wire so that there is a place for the RF current to flow, and the feedline is decoupled. A tail, if you will, for the dog to wag. 72/73, Joe E., N2CX From owner-qrp-l@Lehigh.EDU Mon Mar 17 12:25:39 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id MAA19297 for ; Mon, 17 Mar 1997 12:25:38 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id MAA19297 for ; Mon, 17 Mar 1997 12:25:38 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35196-38389>; Mon, 17 Mar 1997 12:24:35 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35166-38389>; Mon, 17 Mar 1997 12:23:34 -0500 Received: from europe.std.com (europe.std.com [199.172.62.20]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id MAA63709 for ; Mon, 17 Mar 1997 12:22:26 -0500 Received: from world.std.com by europe.std.com (8.7.6/BZS-8-1.0) id LAA05297; Mon, 17 Mar 1997 11:27:59 -0500 (EST) Received: from localhost by world.std.com (5.65c/Spike-2.0) id AA25538; Mon, 17 Mar 1997 11:27:58 -0500 Message-Id: Date: Mon, 17 Mar 1997 11:27:58 -0500 (EST) Reply-To: tmh@world.std.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: tmh@world.std.com To: "Low Power Amateur Radio Discussion" Subject: Backpacking: "self-contained" antennas Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-To: QRP-list X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO For backpacking I'm interested in antennas that are self-contained. By this I mean -- no radials -- no supports needed (trees, YLs) -- zero or asymtotically close to zero setup time We hike in the White Mountains of New Hampshire. Above 4,000 you're in alpine-tundra. No trees, just rocks and lichens. Monster storms come in from Canada on very short notice (the highest wind speed ever recorded was on Mt. Washington, 231mph if I remember correctly), sending everyone scurrying. Once we've reached a summit we typically eat lunch and spend a few hours. It's here I'd like to operate during the day on 20m. Other hikers will come by and I'll get to sell ham radio, etc. For these conditions antennas that meet the above requirements are pretty much mandatory. Radials are trip-hazards and might scare people away. There are no trees for dipoles. You have to be able to pack up and leave quickly. Can people suggest antennas that meet the above requirements? I have already built a Distributed Capacitance Twisted Loop (DCTL) out of 300-ohm twin lead (it's only a couple of feet on a side, and can hang from a walking stick). I'll try this little gizmo out this season. Don't know how it will be for QRP. I'm currently experimenting with two pieces of PVC tubing 1/2" diameter that go together, with a Radio Shack metal whip on the top. The total length is about 11' and it takes 10 seconds to set up (I'll leave it strapped to my backpack, sitting on the ground, for support). I would like to try *linearly loading* 1/2wl onto this (just to experiment with linear loading). If it doesn't work I'll wind it on inductively. I'll also have a 1/2wl counterpoise wrapped on the bottom. Is this 1/2wl vertical with counter-poise a theoretically valid antenna? Can I feed this arrangement with coax? -- Tim N1PAZ From owner-qrp-l@Lehigh.EDU Mon Mar 17 17:33:26 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id RAA09090 for ; Mon, 17 Mar 1997 17:33:25 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id RAA09090 for ; Mon, 17 Mar 1997 17:33:25 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <34845-38389>; Mon, 17 Mar 1997 17:31:22 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34976-18420>; Mon, 17 Mar 1997 17:29:44 -0500 Received: from bonny.hol.nl (root@bonny.hol.nl [193.67.155.250]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id RAA43106 for ; Mon, 17 Mar 1997 17:28:52 -0500 Received: from dial025.hol.nl (dial025.hol.nl [193.67.155.25]) by bonny.hol.nl (8.7.1/8.7.1) with SMTP id TAA10679 for ; Mon, 17 Mar 1997 19:58:43 +0100 (MET) Message-Id: <199703171858.TAA10679@bonny.hol.nl> Date: Mon, 17 Mar 1997 19:58:43 +0100 (MET) Reply-To: PA3ASC@mailbox.hol.nl Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: PA3ASC@mailbox.hol.nl (Mike Perry) To: "Low Power Amateur Radio Discussion" Subject: Subject: Re: Backpacking Antennas Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: mperry@mailbox.hol.nl X-Mailer: Windows Eudora Version 1.4.4 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO Dan, Cla, FWIW, In his book "HF Antennas for All Locations" (Chapter 4, 1 Edn.) Les Moxon G6XN is very clear about an end-fed wire antenna needing a counterpoise and he goes on to explain why a classical Zepp will never work well. D> From: Daniel C Winkler D> Incidently, the end fed wire is still a dipole. [...snip...] D> You need a "counterpoise" to act as the other leg of the dipole. >From Cla KA0GKC : C>You do not need a counterpoise to end feed a half wave dipole. [..snip..] C>Examples are the Zepp and J-pole antennas. Hope this helps. [Don't tell oi, tell 'ee] 73 de PA3ASC -- Best regards from The Netherlands, Mike Perry. [e-mail :- PA3ASC@mailbox.hol.nl ] =-=--=-=--=-=-=-=-=-=--=--=--=-=-=-=-=-=-=--=-=-=-= From owner-qrp-l@Lehigh.EDU Tue Mar 18 02:39:22 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id CAA27037 for ; Tue, 18 Mar 1997 02:39:21 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id CAA27037 for ; Tue, 18 Mar 1997 02:39:21 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35433-49543>; Tue, 18 Mar 1997 02:39:07 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <35386-50058>; Tue, 18 Mar 1997 02:37:39 -0500 Received: from x5.boston.juno.com (x5.boston.juno.com [205.231.100.23]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with ESMTP id CAA121896 for ; Tue, 18 Mar 1997 02:37:31 -0500 Received: (from dwink@juno.com) by x5.boston.juno.com (queuemail) id C[H02829; Tue, 18 Mar 1997 02:36:07 EST Message-Id: <19970317.234239.4951.3.DWink@juno.com> Date: Mon, 17 Mar 1997 23:21:49 PST Reply-To: dwink@juno.com Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: dwink@juno.com (Daniel C Winkler) To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas References: <199703171411.IAA27791@spacestar.net> X-To: aplitech@Spacestar.Net, Monte@pacificrim.com, qrp-l@lehigh.edu X-Mailer: Juno 1.00 X-Juno-Line-Breaks: 0-25,27-31,33-46,48-63,65-70,72-75,77,79,81-82, 84-87,89-100 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: O On Mon, 17 Mar 1997 08:10:42 -0600 "Claton Cadmus" exclaims: >ooonnnnk! Wrong! > >You do not need a counterpoise to end feed a half wave dipole. Well, I wondered if anyone would take the bait, but at the moment I am too tired to do justice to the debate I had planned. It goes something like this: Sorry Clayton, but you are wrong. I repeat, a halfwave resonant antenna CANNOT be fed at it's end. It's impedance is not a few thousand ohms, it is truly infinite, and it will not accept energy. But there is a catch. If you move in from the end, just a tiny bit, the impedance becomes finite. Very large, but finite. If you move in just a little further, you get the few thousand ohm figure that everyone talks about. When you put an antenna tuner on the end of that resonant wire, you are adding the "counterpoise" that it needs. Your coax to the tuner is part of that counterpoise. The rig and the key and you are all part of that counterpoise. With a perfect-halfwave wire, the impedance is so high that you *cannot* decouple these lines. They become the other end of the dipole whether you like it or not; whether you believe it or not. In the case of the J-pole and Zepp antennas, you are not feeding a half- wave resonant wire alone, you are feeding THE FEEDLINE, which is attached to a halfwave resonant wire. The feedline is obliged to radiate some portion of the signal in order to couple energy to the halfwave dipole (that amount can be very small, however). Here are two questions to ponder. If I had a point-source rf generator and stuck it on the very end of a resonant halfwave antenna, would the generator excite the antenna? What is the tangent of 90 degrees? Now you may feel that I am picking nits, and there may be an element of truth to that, but I think it is important that people understand this point. When you say you are feeding a a single wire at its end, you are deluding yourself. That wire is one portion of a dipole. It can be helpful to know what the other portion of that dipole is, if you want to decrease losses. Feedpoint impedance on a resonant dipole varies as the tangent of the electrical angle of the feedpoint from the center of the dipole. Tan(89) = 57.3 Tan(89.9) = 572.96 Tan(89.99) = 5729.578 Tan(89.999) = 57295.78 Tan(89.9999) = 572,957.8 . . .and we still aren't at the "end" of the wire! But we are about 0.1" from the end of a 40m dipole (67'). That's only twice the diameter of 16 gauge wire. The few thousand ohm impedance feedpoint will occur about 1" from the end. So we don't need MUCH of a "counterpoise", but don't believe for a second that it is not there! Do I hear a "so what?" Well, I think you end up losing more power than you need to in your matching circuit when you try to match impedances that high. If you make that feedpoint a few *feet* in from the end, instead of merely a few inches, the impedance comes down to very reasonable values, and you will lose less power in circulating currents in your matching circuit. I must go to bed. I'm sorry I can't do better on this explanation, but I hope everyone following this thread now sees both the validity and the absurdity of my initial statement. ps- I read the Communications Quarterly article. 73, ; D DWink@Juno.com Dan Winkler N7IVR Seattle, WA ----------whom the gods would destroy, they first make proud ---------- From owner-qrp-l@Lehigh.EDU Tue Mar 18 10:38:47 1997 Received: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id KAA21889 for ; Tue, 18 Mar 1997 10:38:46 -0500 (EST) X-Received-x: from fidoii.CC.Lehigh.EDU (fidoii.CC.Lehigh.EDU [128.180.1.4]) by oucsace.cs.ohiou.edu (8.7.6/8.7.1) with ESMTP id KAA21889 for ; Tue, 18 Mar 1997 10:38:46 -0500 (EST) Received: from Lehigh.EDU ([127.0.0.1]) by fidoii.cc.lehigh.edu with SMTP id <35209-49543>; Tue, 18 Mar 1997 10:33:47 -0500 Received: from nss2.CC.Lehigh.EDU ([128.180.1.26]) by fidoii.cc.lehigh.edu with ESMTP id <34976-50058>; Tue, 18 Mar 1997 10:32:00 -0500 Received: from Spacestar.Net (root@Larry.Spacestar.Net [204.220.147.2]) by nss2.CC.Lehigh.EDU (8.8.5/8.8.5) with SMTP id KAA68113 for ; Tue, 18 Mar 1997 10:31:53 -0500 Received: from groucho.spacestar.net by Spacestar.Net (8.6.11/SMI-4.1.R931202) id JAA15127; Tue, 18 Mar 1997 09:32:05 -0600 Message-Id: <199703181532.JAA15127@Spacestar.Net> Date: Tue, 18 Mar 1997 09:19:53 -0600 Reply-To: aplitech@Spacestar.Net Sender: owner-qrp-l@Lehigh.EDU Precedence: bulk From: "Claton Cadmus" To: "Low Power Amateur Radio Discussion" Subject: Re: Backpacking Antennas X-To: "QRP-l" X-MSMail-Priority: Normal X-Priority: 3 X-Mailer: Microsoft Internet Mail 4.70.1160 X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN Status: RO I thought about answering Daniel's comments but just don't have the time. I refer to real practical antenna's, not imagined RF point sources in space and antennas with no thickness. For those of you interested in end feeding a half wave resonant wire I refer you to the fine article on page 61 of Communications Quarterly Fall 1996. And the graph, referenced in the above article, in the Radio Handbook 1989 edition on impedance versus wavelength with respect to conductor size. And again, you can endfeed a half-wave wire antenna without the need of a counterpoise. (i.e.: an extra length of wire thrown about) It's done everyday in millions of antenna installations. Yes, you need a matching network of some kind. If you wish to call that a counterpoise go ahead. I for one call it a matching network. 73 de KA0GKC Cla