++++++++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 20:24:06 -0700 From: "Ron D' Eau Claire" Subject: RE: [Elecraft] Superantennas MP-1 Julian wrote: To > my surprise, I go 1.0:1 on 20m, which was very active one of the days I > listened, and 1.1:1 on 40m...both better than here at the house. I was > easily able to pick put stations in California (lots of W/K6's), > Oregon-Washington, and even Colorado. Picked a few K0/N0s while I was > listening, but as should be expected, the -6 area was most active > for what I > was receiving. > > The thing that really blew me away abou this was the > rocky-clay soil had > better characteristics -- even in a valley -- than I got here at > the house. Better 'characteristics' for a low SWR perhaps, but the worse the ground and the poorer the radiation efficiency of the antenna system, the easier you should expect your ATU to find a match under most conditions. You should expect to find the tuning a lot less 'finicky' since you are pumping most of the r-f into a very broadband resistor (the poor earth) instead of a higher-Q radiator (the whip). Perhaps a better measure would be the bandwidth of the system. If the short antenna exhibits a very narrow frequency range over which the SWR will be reasonable without the KAT2 retuning, that would be a very good sign that the system efficiency is high. In an efficient system, a short radiator will have less bandwidth, and the bandwidth will drop very fast as the physical length of the radiator drops below 1/4 wavelength. If it doesn't, you have a resistive loss in there somewhere. It might be a lossy earth connection, a lossy loading coil or some other resistor that consumes a good part of the r-f instead of letting it be radiated. Ron AC7AC K2 # 1289 +++++++++++++++++++++++++++++++++++ Subject: RE: [Elecraft] Superantennas MP-1 Robert Perkins wrote: > I also recalled an article in QST a year or so ago where strips were used > like an Outbacker tripod. > In my simple-minded gullibility, I bought an Outbacker with the fancy tripod mount several years ago. It worked, but when compared side-by-side on several bands to a $5 dipole, my $600 Outbacker setup was absolutely and horribly pitiful. I believe portable vertical antennas of this sort seem to work only in the sense that even a set of metal couch springs can be made to radiate something. I've experimented with antennas of many types suitable for portable operation for more than 25 years of camping and backpacking operations. I have NEVER found anything that even begins to approach the performance of a simple resonant dipole. Certainly nothing except an end-fed wire is as cheap to assemble, and as light and compact to stow. I recently put together a 40m portable dipole for my K1, with an insulator and jumper in the middle of each leg that can be manually opened for 20m operations. I also have a dipole of similar construction that I've used for years that covers all HF bands from 40m to 10m. The only rationale for using a portable vertical, IMHO, would be in areas where end-support for a dipole is lacking. 73, Mike / KK5F ++++++++++++++++++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 14:16:13 -0400 From: "Steve Lawrence" Subject: RE: [Elecraft] Superantennas MP-1 (Portable Antennas... really) Mike, I was interested in your comments concerning dipole performance vs. compact vertical antennas in a portable environment. While I have no practical experience yet (my K2 is about 1/2 complete), I'm looking for a good "first portable antenna" choice. I'm not (yet) interested in minimizing weight for backpacking, but would like to bundle the K2, antenna, battery, etc. into a small suite case for field deployment. Mentally, I'm beginning to focus on a center fed dipole (fed with either small ladder line or even 300 ohm TV style twin-lead) cut for 40m, and (hopefully) tuning it for the higher bands through the use of the KAT2 tuner. I'm also interested in the possibility of an off-center fed dipole for some of it's multi-band capabilities. I'm looking for field experience on either of these designs in general, and some practical experience concerning several aspects... 1.) Dipole vs. off-center fed dipole: advantages? disadvantages? designs people have used that worked well? 2.) Use of ladder line vs. TV "twin lead": feed line for portable multi-band use? 3.) Balun: what type to use to connect to the KAT2 tuner? should it be used? choke vs. toroidal? 1:1 vs 4:2? 4.) KAT2: how well does it work for this proposed antenna? Thanks Mike. I would love to make my first portable K2 operation a success! 73, Steve aa8af +++++++++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 10:49:39 -0700 From: Louis Hlousek Subject: Re: [Elecraft] Superantennas MP-1 <>> You can model all these antennas in EZNEC using real ground and you will find the same thing with the models. (It is kind of tedious inputting the model of a the couch spring.) An interesting thing is that short loaded whips outperform 1/4 wave verticals if you neglect the losses in the coil. I should also point out that except for losses in matching networks and feedlines there is no benefit in having the antenna resonant. Luigi W7DZN +++++++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 13:56:31 -0500 From: "James Parsons" Subject: Re: [Elecraft] Superantennas MP-1 (Portable Antennas... really) Please post your answers here. These are good questions and I would like the answers also. 73 de Jim, K5ROV... > Mike, > I was interested in your comments concerning dipole performance vs. > compact vertical antennas in a portable environment. -----snip-------- +++++++++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 16:32:25 -0400 From: "Morrow, Michael A." Subject: RE: [Elecraft] Superantennas MP-1 Luigi wrote: > I should also point out that except for losses in matching networks and > feedlines there is no benefit in having the antenna resonant. > But often, that is one heck of a significant benefit. Additionally, one may be able to use a resonant dipole satisfactorily without any tuner for rigs that haven't the luxury of a built-in tuner. I always operated my DSW rigs that way, resulting in a super-small total carry weight. 73, Mike / KK5F +++++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 16:01:12 -0500 From: fkamp at home.com Subject: Re: [Elecraft] Superantennas MP-1 (Portable Antennas... really) Steve, On you antenna concerns, I have used all three, the plain dipole, the dipole fed with ladder line, and the off center fed dipole. Each work about the same. There is no real difference in performance or efficiency. The plain dipole is the easiest using coax as a transmission line. 75 ohm coax if it is flattopped at half-wavelength height. 50 ohm is a better match if the antenna is installed as an inverted vee. Use a choke balun to keep RF off the coax shield. The dipole with ladder line is an all band antenna when used with a tuner. It needs no balun because the feedline stays balanced all the way to the tuner. Dimensions are not critical. 50 feet per side will cover all the way down to 80 meters with the proper tuner. SWR on the feedline might be pretty high at some frequencies but it does not matter because ladder line is close to lossless. The off-center fed antenna is also known as the Windom. I use one on 75 and as an all band SWL antenna. If you cut the antenna for 80 meter CW it will also work well in the CW portions of all evenly related harmonic bands. Such as 3.5, 7.0, 14.0, 28.0. Since mine is cut for 3.9, I end up with 3.9, 7.8, 15.6, 31.2. That is not a problem since I have a built-in antenna tuner, but without the tuner it would be tough to use such an antenna as an all band antenna. My Windom has one leg 40 feet long, the other leg 80 feet long. It is installed as sort of a modified inverted vee. One end is at 35 feet, the center is at 48 feet, the other end is at 20 feet. It is fed with 47 feet of 300 ohm twin lead. The twinlead goes to a 4:1 balun. Then coax to the radio. At one point I did have it cut for 3.55 mHz as the lowest frequency and it had less than 1.3:1 SWR on 80, 40, 20, and 10 meter CW band segments without having to use a tuner. The worst problem this antenna can cause is harmonic radiation. That is not a problem with modern equipment that filters harmonics, but should you get an old boatanchor or poorly designed homebrew rig feeding it, you might get a card from the FCC. Standard dipoles tend to subdue harmonics. At least more so than the Windom. I have used all three of these antennas at different times over a period of about 25 years. All of these three antennas were mounted in exactly the same way. Their performance was about the same. No real difference. I prefer the Windom because it makes a better SWL antenna. Frank Kamp K5DKZ ++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 15:55:02 -0700 (PDT) From: Jessie Oberreuter Subject: RE: [Elecraft] Superantennas MP-1 (Portable Antennas... really) I believe this month's QEX has an article addressing portable QRP OCF dipoles in the 'RF' section. NEC data and a design for a minature 4:1 current balun are presented, but the author's general conclusion seems to be that the OCFD is too sensitive to initial conditions to be a worthy competetor against clip adjustable dipoles or minature trap antennas. Still, the OCFD holds a facination. I'm going to be trying a loaded vertical OCF dipole for 160 and up this field day -- I'll let you all know how it goes. On Wed, 23 May 2001, Steve Lawrence wrote: > Mike, > I was interested in your comments concerning dipole performance vs. > compact vertical antennas in a portable environment. ----------snip----------------- +++++++++++++++++++++++++++++++++ Date: Thu, 24 May 2001 00:32:31 +0000 From: Michael Rioux Subject: RE: [Elecraft] Superantennas MP-1 As one who has operated from many DX locations - AMEN!!! 73 de W1USN - Mike I I >have NEVER found anything that even begins to approach the performance of a >simple resonant dipole. ++++++++++++++++++++++++++++++++++ Date: Wed, 23 May 2001 20:31:37 -0400 From: "Don Wilhelm" Subject: Re: [Elecraft] Superantennas MP-1 (Portable Antennas... really) Steve, (longish response) In my experience with antennas - particularly dipoles - is that they do not have to be resonant to do a good job of radiating a signal. Effeciency decreases dramatically if the length is less than 1/8 wavelength, and the radiation pattern will break into lobes if the length is more than 5/8 wave. One of the nice lengths for 40 thru 10 meters is 44 feet or 88 feet for 80 thru 20 meters (higher if you don't mind the extra lobes on the pattern). See L. B. Cebiks website for more information www.cebik.com and look for something like 'If I could have only one antenna'. Of course, mutiband antennas should be fed with a low loss line. I have used both 300 ohm twinlead and 450 ohm window line and true open wire feeders. The open wire feeders are the best, but the 300 ohm twinlead is fine for most uses too - the loss is not THAT great. A while back there was a discussion on QRP-L about feedline loss, and Ed Loranger did some tests - found that twisted pair made of the teflon insulated wire that N2GO sells shows quite low loss too (comparable with 450 ohm ladder line) and has a characteristic impedance of about 200 ohms - make the antenna from the same wire and you have a lightweight combination that is somewhat resistant to tangles, and can be erected as a dipole with 2 supports, on inverted vee with one support, or as an 'L' antenna in difficult situations (one leg as a vertical and the other as a single radial if you like that picture better) - (and yes - you can feed a vertical with balanced line). Just because you are feeding an antenna with 300 ohm or 450 ohm transmission line does NOT mean that you transmitter or ATU will see that impedance. You have to compute or measure the input impedance to know for sure - if the transmission line is a quarter wavelength long, it will change a high impedance to a low one (or vice versa) and if it is a half wwave long, it will repeat the input impedance. Bottom line here is to measure your feedline so you can compute the actual feedpoint impedance. Many hams assume they need a 4:1 balun if they are using 300 ohm or 450 ohm line, and many times a 1:1 balun is more appropriate - you don't know unless you measure or calculate the input impedance to the feedline. If you want only a single band, a resonant dipole fed with coax is the easiest solution. I long ago used off center fed dipoles - a windom fed with 300 ohm line. It worked fine, but I needed a really stiff RF ground to keep the equipment in the shack from biting me with RF. There is no way that OCF antennas can have equal and opposite currents on the feedline (unless it is fed at an odd multiple of 1/4 wave from one end), so do expect the feedline to radiate with these antennas. The KAT2 is capable of handling a wide range of impedances (except very high ones), so you should find a match with most any reasonable antenna/feedline combination that you can throw at it. 73, Don Wilhelm -Chapel Hill, NC W3FPR home page: http://www.qsl.net/w3fpr/ QRP-L # 485 K2 SN 0020 mailto: w3fpr at arrl.net ++++++++++++++++++++++++++++++++++++++++++++ Date: Fri, 25 May 2001 14:31:56 -0400 From: "Morrow, Michael A." Subject: RE: [Elecraft] Portable Antennas... Fran wrote: > The antenna that I built was made from a piece of zip cord. Think of it > as > a pair of dipoles, one for 80 and one for 40, that are glued together with > a > common feed point. I intended to feed it with 300 ohm line. > I question the use of zip cord, or computer ribbon cable, or what have you, for antenna wire. Good wire is cheap, at least in the quantities needed for a decent portable dipole. I also question the use of micro-diameter wire and coax for those who use that stuff (wire is light weight). The best portable dipole material I've ever found is a 12 ga. product known variously as "Flex-weave" or "Super-weave." This copper wire is comprised of bundles of very small diameter wire (well over 100 strands) woven such that even the 12 ga. product is incredibly flexible. It is a joy to work and to solder. It is nearly impossible to fatigue fail. It usually goes for about $0.18 per foot bare, and about $0.27 per foot insulated. It's also available in a smaller diameter at lower cost. I've tried various twin lead (450 ohm window, 300 ohm heavy-duty TV, regular 300 ohm TV) feed lines over the years and wound up discarding all of them. I found there to be significant bad effects when any excess twin lead was bunched up, rolled-up, or just laid across the ground on the way from the antenna to the tuner. > The original intention was to erect it as high as possible in an L > configuration. The advantage of this was that it is easy to > predict > the length of the feed line inadvance. I have a good idea how far away > the > operating position will be. > I have found the opposite to be true. As one sets up a portable station from one camp to another, it's usually difficult to know before the trips begins how high, how far, how oriented the antenna will be from the antenna to a comfortable place to locate the rig and campsite. > What is usually not known is how high the support will be. > I have had very good performance with resonant dipoles on 40 through 10 meters, even though I almost never have any part of the dipole more than about eight feet above the ground. > I had a ground wire come into my tent through the same hole as the > feed line. > I don't think a ground would be beneficial for a balanced inverted-V, or dipole. I'll use this as an opportunity to reprise my list of the advantages of a tuned dipole for portable operations: (1) You don't need ANY ground. (2) You don't need ANY counterpoise. (3) You may not need a tuner, depending on how upset you get running into a less than perfect VSWR. (4) You really DON'T need to worry about getting it way up in the air. (5) You can use coax feed (since it's a resonant dipole). (6) A balun really ISN'T required (I use them only in a permanent installation). (7) They are light-weight and low-bulk. (8) They are very inexpensive. Practically speaking, 50 to 75 ohm coax won't make any real difference. I use either RG-8X or RG-58. I wouldn't consider using RG-174 (line-loss, fragility, difficulty of getting a durable connector installation, etc.) I have tried multiband trap dipoles for portable operations. I discarded that idea. Traps, home-made or commercial, are heavy, bulky, and make the roll-up of the antenna for storage difficult. They can be lossy. They can promote radiation from the antenna system of second harmonic spurious output from our QRP rigs (which often barely meet FCC requirements). A better approach to traps (IMHO) is to put insulators in each dipole leg to form wire segments that can be connected by a short jumper across the insulator(s) to get a desired resonant length. I have one home-made portable dipole with six such insulators and integral alligator clip jumpers in each leg to create a tuned no-trap resonant dipole for any HF band from 40m to 10m. I made the insulators out of 3/8 inch O.D. PVC water tubing. Sure, you have to go to the antenna and manually change jumpers to change bands, but for a portable installation, that is a trivial disadvantage. It works like a champ. I worked 40 countries with it on a weekend camp trip a couple of years ago with it only about seven feet about ground at the highest point. (E-mail me if you'd like detailed construction details.) I would consider using a vertical only if I were in some place without trees to support the dipole ends. I would use a random wire with counterpoise only if that was all I had. I'll mention that I've also used at fixed camps the fancy Outbacker vertical and tripod (extremely poor performance for a terribly high price), the MFJ 30m to 10m loop (OK for what it was, expensive, but still unsatisfactory overall), and various "G5RV" types (needs to be hoisted high enough to get twin-lead section above the dirt, definitely needs a tuner, and I'm not convinced it works well on the WARC bands). I have never seen any technical advantage to an off-center-fed antenna (Windoms, end-fed Zepps, etc.), so I've never tried those. My apologies for the length of this post, and the fact that I can't cite numerical dB comparisons. The nicest thing about a dipole is that it won't cost you much to try it. The same can't be said for some of the other antennas I've tried. 73, Mike / KK5F +++++++++++++++++++++++++++++++++++++++++ Date: Fri, 25 May 2001 15:37:31 -0500 From: "Stuart Rohre" Subject: Re: [Elecraft] Portable Antennas... In the field, if you disconnect your antenna when you are NOT using the radio, (ALWAYS A GOOD IDEA), you do NOT need a ground wire with a balanced antenna such as a dipole!!!! This is a great misconception of the average ham. The ONLY reason for using a ground rod ever is for improving static discharge, and protection of the home station from indirect lightning induction. If you get a direct hit, a single ground rod is not going to do much to help stave off damage. Out in the tent, there is no need for a ground rod, if you are operating off a battery, or solar panel. You do want to keep your balanced line whether 300 or 450 type off the ground (dirt), and away from conductors for a couple diameters of the wire. Thus, use some nylon line to tie it to hang off your tent metal frame rather than lashing it to the metal frame directly. Use a direct run to the rig, and dont coil up any excess. If you do not want to cut your line to length, simply run an indirect path to the rig to use up line length. Twist the line every 18 inches or so to avoid coupling effects to metal in the environment or nearby trees, etc. This helps cut down on noise pickup in campgrounds that do have AC lines overhead. Of course, keep antennas and feeders away from lines as far as possible, and keep the antenna wire at right angles to any lines. Hope this helps, by the way the Pythagorean theorem can be applied to work out the feedline needed, if the rig is at the base of the fed portion of the dipole. The hypotenuse is half the dipole of the Vee. Squared it equals the sum of the squares of the distance from under end of dipole to under the center feed point, and the square of the vertical distance, which is the feeder. GL, 73, Stuart K5KVH +++++++++++++++++++++++++++++++++ Date: Tue, 29 May 2001 08:00:45 -0700 From: Eric Swartz WA6HHQ - Elecraft Subject: [Elecraft] [Fwd: K5OOR: FW: elecraft list] Virgil Stamps wrote: > > Eric, I still have no connection to elecraft at qth.net. I was wanting to post > a message to the K2 community. Please be so kind to pass it along. Virgil > > Are you interested in Pedestrian Mobile? I sure am. Especially after finding > a very good 5-band hand carried dipole. You can build it for less than $30 > from parts you can get at RadioShack and the local hardware store. I built > mine in an afternoon. The K2 tunes it perfectly. I have worked dx on 20, 17 > and 15 meters. I also made contacts from my hotel room by sticking the hot > side of the antenna out the window. The whole antenna shrinks down to less > than 2 feet. A great antenna for pedestrian mobile or walk-about portable > operation. Last night I worked ZL2BK mobile in New Zeland on his similar > dipole. Both at 12 feet. > > I have joined a group called HFPACK http://groups.yahoo.com/group/hfpack > that meets on 18157, 21437, 28337. Right now, the group is dominated by > FT817's and I was the first K2 to join in. So I challenge you to check it > out. Open to CW or SSB. > > See the antenna at: http://www.qsl.net/w3ff/photo.htm This antenna set a > long path record of 22,593 km recently. > The instructions to build it at are at http://www.qsl.net/w3ff/W3FF_5.htm > > There is going to be a national meeting of the HFPACKers on the day before > field day. I hope to work many K2's on that day. > 73's de K5OOR, Virgil > K2 #515 +++++++++++++++++++++++++++++++++++++++++ Date: Thu, 28 Jun 2001 20:50:31 -0500 From: "Kenneth Christiansen" Subject: [Elecraft] 44 ft dipole with 22 ft 300 ohm lead I do a lot of camping and I need to thank this reflector for my new camping antenna. 20 years ago I used dipoles cut for 40 and 20 fed with coax and my FT-100E. I was off the air for several years and changed campers, rigs and camping locations. I bought a fiberglass camper and a new rig but for several reasons I could not use the old full length dipoles. I set up a 16 ft copper pipe vertical using the steel frame of the 16 ft fiberglass camper as a counterpoise and for the last three years thought I was having good results. This week end I set up this vertical antenna and my new 44 ft dipole with 22 ft of 300 ohm twin lead (NO BALUN) and tuned each with the KAT2. I could compare them with the push of the ANT button and I was in for a surprise. The dipole almost always was stronger and had less QSB. I also gained back 30 and 40 meters. The dipole was only 10 ft off the ground using PVC pipe for supports while the vertical was the 16 ft piece of copper pipe and the 16 ft trailer frame counterpoise. I also tried my ZM-2ATU and it works well but the KAT2 is quicker and easier to use. I could not see any difference grounding the rig, reversing antenna leads or find any indication of RF in the camper so decided to use the KAT2 only I worked 7 CW QSOs on 20, 30, and 40 from the State Park over three days. The QSOs were all over the country and I felt they were well balanced QSOs under poor band conditions. Some of the QSOs were at 5 watts and the rest were at 15 watts. This antenna is not as good as my CL33 beam at home but it is sure a keeper for the park. I put my old vertical in storage when I got home this evening. I hope this information helps anyone that is trying to decide what simple antenna to use. I tried a 13 ft 300 ohm lead and that worked well on 20 and 30 but even the ZM-2ATU was not able to tune it on 40. I then made the lead 22 ft as recommended and like magic it worked and the tuner settings stayed consistent from day to day. W0CZ Ken Christiansen K2-1031 ++++++++++++++++++++++++++++++++++ Date: Sat, 07 Jul 2001 22:09:30 +0000 From: Brendan Minish Subject: Re: [Elecraft] K2 At 09:36 06/07/2001 -0700, Daryl Cline wrote: >Also I am interested to know what >different people use for light weight antenna systems. >Especially those who backpack. Thanks. Bonnie Crystal KQ6XA Has come up with this clever and very versatile design for a portable wire antenna, it works a treat with the K2's internal ATU see http://www.qsl.net/kq6xa/antenna/ I have a short piece of coax with 2 banana plug sockets on one end and a BNC plug on the other end to connect my miniback to the K2, no need for a balun with the K2 if you have the ATU installed. Bonnie's main page is at http://www.qsl.net/kq6xa/ The K2's internal tuner Is REALLY good, It matches everything I have ever tried it on, It even matched a 2m rubber ducky on 40m, I even managed a local (~4 Miles) QSO with the Rubber ducky. You will not regret choosing a K2. - -- Brendan Minish EI6IZ ei6iz at oceanfree.net PGP key available from key servers wwwkeys.pgp.net +++++++++++++++++++++++++++++++ Date: Thu, 26 Jul 2001 14:26:11 -0700 From: "Ron D' Eau Claire" Subject: RE: [Elecraft] Portable Antenna Question Stuart wrote: > I would have expected better results the lower the antenna is placed for > NVIS. Tom, N0SS dropped me a line saying that a QST article a few years back about NVIS mentioned 1/8 wavelength high as being optimum. I don't have that QST handy but I want to look into it. My figures were based on articles going back over many decades on 'cloud warmers' for very short skip work (Now called NVIS). They suggest that the height is not particularly critical provided that it does NOT EXCEED 1/4 wavelength. Above that height, the lobe 'straight up' diminishes very quickly as more radiation is directed off at lower angles. The problem with lower antenna heights is that the ground losses escalate as the antenna gets closer to the earth. If you look at the dipole as the driven element of a 2-element beam and the earth as the reflector, the handbook nomographs will show that maximum gain occurs at just about 0.2 wave spacing. That seems to agree with the empirical data for 'cloud warmers' that I've seen up until now. That said, Tom's suggestion is one I'd try as well. Drop the antenna down to 1/8 wave and see if that helps based on what he found in the QST article. For one thing, the physical height and electrical height are usually not the same unless one is over salt water - they might be much different depending upon the terrain and soil conditions with the antenna electrically higher than one might think. Stuart makes an excellent point about the elevation. Getting something off the edge of an escarpment might be a good option. Given the height and a relatively unobstructed path to the locals, direct 'ground wave' might work as well. Normally ground wave is very limited on 7 MHz because of the effect to the earth absorbing the signal - but in this case most of that earth is a mile below the signal . Ron AC7AC K2 # 1289 +++++++++++++++++++++++ Date: Thu, 26 Jul 2001 16:53:31 -0500 From: "Stuart Rohre" Subject: Re: [Elecraft] Portable Antenna Question Ron, Good points about the beam analogy and 1/8 wave elevation for the NVIS. Of course, in the mountain forest a lot of things are going on. 9M2AA found that optimum NVIS in forest happened about at 4 MHz, due to absorption. we certainly have given the poster some ideas to try next trip. Hope to hear how it worked! 72, Stuart K5KVH +++++++++++++++++++++++ Date: Mon, 30 Jul 2001 08:33:53 +0200 From: david.reid at philips.com Subject: [Elecraft] re antenna for indoor use Lamar, have a look at my article on magntic loops...this is an ideal antenna for low band working from indoors (especially with QRP). It is not very efficient - but it does work well with low background noise. I use one from hotel rooms when working in Germany. the article is on my website: http://www.qsl.net/pa3hbb go to the Articles section and read the article "Practical Experiments with Magnetic Loop Antennas" Perhaps it will help get you QRV. 72/73 de Dave PA3HBB / G0BZF/ PB6X http://www.qsl.net/pa3hbb http://www.qsl.net/pb6x (contest station callsign ++++++++++++++++++++++++ Date: Mon, 30 Jul 2001 11:56:42 -0700 From: "Ron D' Eau Claire" Subject: RE: [Elecraft] Trip Report and Portable Ant for Close-in QSOs Carter Craigie N3AO wrote: >the > vertical wire up > the tree is the way to go for me. > > BTW, the 50-foot length of wire (still using the 33-foot-long > radial) tuned > to a 1.0 to 1 SWR on 20 meters at 14.060... I didn't try 20 meters, but I > will the next time, so I can learn more about what goes on with portable > antennas. I was really curious about whether you could get a 'ground wave' over that distance without any earth in the way to absorb the signal since earth was about a mile below you. The directivity of that arrangement is somewhat frequency selective. Where the antenna is one half wave overall (1/4 wave vertical and 1/4 wave horizontal) or LESS, it will show about 5 dB preference in the direction the horizontal "radial" is pointing. But if you QSY up where the overall length reaches 1 wavelength (1/2 wave vertical and 1/2 wave horizontal) the pattern will shift 90 degrees and the radiation angle will be higher. I haven't tried mixed lengths of radial and vertical sections. Thanks for the report on the one-radial 'vertical'. Glad it worked. It's always good to get some 'field test' results back! Ron AC7AC K2 # 1289 ++++++++++++++++++++ Date: Wed, 15 Aug 2001 17:16:56 -0500 From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] Question about a hunk o' wire Mike: As a Field Tester for the KAT2 and the KAT1, I threw just about anything I could think of at them and with VERY few exceptions, they tuned it with no complaining! I did, in most instances, have a 'counterpoise' wire attached to the case of the rig (more difficult with the K1 since It doesn't offer a ground terminal per se). But even when it wasn't connected, the ATU generally tuned to 1.5:1 or less. When no counterpoise was provided, I did find a much higher incidence of "RF in the shack" however. when I give presentations of the K1/K2, I usually take a 70' and a 30' length of wire. The 70' length (if I can get it stretched out), is usually connected to the center lead of a 15' length g-174/U coax thru 35 ferrite beads (a la W2DU 1:1 balun), and the 30' goes to the shield of the coax and often lays on the ground or over nearby bushes. When I've really cramped for space, I'll omit the coax/balun and go directly to the back of the ATU and to a ground on the rig. 73 - Tom Hammond N0SS >>I guess I should have clarified my question. I fully realize that actual >>performance of this hunk o' wire is more than likely dismal at best. I >>was just surprised at how easily the K2 loaded it up, particularly >>without any ground or counterpoise. I had expected the tuner to need >>some type of ground or counterpoise to effect such a good match. >Mike Boice, KW1ND ++++++++++++++++++++++++ Date: Thu, 20 Sep 2001 19:01:11 -0100 From: "Julian, G4ILO" Subject: [Elecraft] mobile/portable antenna for the K2 I have had good results on 20m and up using 10W of SSB and monoband mobile whips such as the Pro-Am type, not just with the K2 but in years gone by with things like an FT-7. You mention using only 5W of SSB, I'm not quite sure why, but it shouldn't make that much difference, being only half an S-point. For mobile whips to work well they must have an effective ground, ideally directly to the bodywork of the car. You really can't get away with using a mag mount. I second the recommendation of Rolf, DL8BAG, that the MFJ magnetic loops work very well if you have space for a 3 foot diameter aluminium hoop in your caravan. I happen to have one to sell. See my web page or email me if interested. 73, - -- Julian, G4ILO. (RSGB, ARRL, K2 #392) Homepage: http://www.qsl.net/g4ilo ++++++++++++++++++++++++++++ Date: Thu, 20 Sep 2001 19:55:31 From: "Mike WA8BXN" Subject: [Elecraft] Re: antenna for mobile/portable Hi have had a lot of fun with a K-1 at 5 W running mobile on 40 and 20 using Hustler resonators with the short mast mounted on the trunk deck. When camping I found the Super Antenna MP-1 works reasonably well on a picnic table or next to my tent when I don't want to string up a wire antenna. With a K-2 you will have more flexibility band wise of course. So the answer is yes, it will work and you will have fun. 73 - Mike WA8BXN +++++++++++++++++ Date: Fri, 21 Sep 2001 16:57:01 +0100 From: "derek warnett" Subject: [Elecraft] Antennas for mobile/portable My grateful thaks to all who sent advice and suggestions re the above- now all I have to do is make a decision and raise some cash !. Someone suggested that a summary of the results might well be of interest to others so here is how they went; Fibreglass poles with either vert. or horiz. dipoles. 3 Screwdriver 2 Perth Outbacker 3 MP-1 Superantenna 1 Hamstick 1 Texas Bugcatcher 1 Hustler 2 Mag. Loop 1 Half wave ant and quarter wave counterpoise 1 Wire slung up tree 1 You have certainly given me food for thought and at the moment am inclined towards either a Bugcatcher or an Outbacker both however are expensive over here so will have to get on right side of " she who must be obeyed". Thanks again to everyone-Regards-Derek ++++++++++++++++ Date: Tue, 23 Oct 2001 08:05:52 -0500 From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= Subject: Re: [Elecraft] portable antenna for business trips GM Rolf: >I would like to gather some information on which antenna to use for >business trips together with my Elecraft K2? Although the K2 definitely >has become my main rig for operation from my home shack, I believe that >K2s like travel every once in a while... In the past couple years, I have been frequently asked to give K1/K2 presentations at various ham radio clubs and hamfests in and around the state of Missouri. In all cases, I have used an antenna consisting of 100' of #20 insulated wire, cut into two pieces of 30' and 70'. I take with me a 30-foot telescoping mast and use it to support the 70-foot wire. I try to get it as high and stretched out as far as possible. The 30-foot wire is used as a counterpoise for 'vertical' 70-foot wire. Of course, it's not all vertical, but it's as close as I can get with only a 30-foot mast . I take a 15-foot length of RG-174/U which has BNC connectors on each end and 35 ferrite beads slipped over one end to form a W2DU-type ferrite-loaded coaxial RF choke. This helps to keep RF off the shield of the coax and a bit away from the rig. I also take a small 4:1 Guanella-type balun for those (very few) cases where the impedance of the 'vertical' is so high that the ATU cannot find a match. With this combination of wire lengths and the baluns, I can operate from 10m through 80m with no problems at all. Of course, if you were not terribly interested in 80/75M operation, you could use much shorter wires for 10m through 40m. If you are interested, pictures of the W2DU-style 1:1 balun and the 4:1 balun are available at: http://home.earthlink.net/~n0ss/qrp_1-1_w2du_coaxial_balun.pdf and http://home.earthlink.net/~n0ss/qrp_4-1_guanella-type_balun.pdf Hope this helps. 73 - Tom Hammond N0SS +++++++++++++++++++ Date: Tue, 23 Oct 2001 03:51:42 -0700 From: lhlousek Subject: Re: [Elecraft] portable antenna for business trips Hello Rolf, My portable antenna consists of two 1/4-wave ribbon cable elements and a collapsible 4.25 m (14’) fishing pole. The pole collapses to 36 cm (14”) and the entire setup weighs less than 0.34 kg (12 oz) including a 6m (20’) RG174 feedline. I use this setup on 40 through 10 meters with the KAT2 and 40 through 15 with the KAT1. Each ribbon cable element has three wires joined at one end and soldered to a small spade lug. The longest wire is cut for 40 meters, the next is cut for 20 meters and the last is cut for 10 meters. The 20 meter wire is separated from the 40 meter wire for 1/2 it’s length and the 10 meter wire is separated from the other wires for 1/2 it’s length. The two elements connect to a BNC to binding post adapter and when spread out give you the classic 40/20/10 meter dipoles. I spread mine out and trimmed the elements for resonance on 40, 20 and 10 but this certainly isn’t necessary when using the tuners. To use this setup in a hotel, I tape the adapter to the base of the fishing pole and run one of the elements along the pole with the 40 m wire dangling from the end and the 20 and 10 m wires dangling from along the pole. I usually attach a small weight (a paper clip) to the end of the 40 m wire. The pole is then stuck out the window and some furniture rearranged to support the butt of the pole. The other element is connected to the shield side of the binding post adapter and stretched out in the room to serve as a counterpoise (or the other end of the dipole, depending on how you look at it). Supporting the butt of the pole might take some creativity. To give you an idea, at the last hotel I put a hassock against the wall under the window and then put a small end-table on its side on top of the hassock. The butt of the pole went under a leg of the end-table and was held in place with some electrical tape. In another hotel with a balcony I was able to rearrange the deck furniture appropriately. In most hotels the windows on the upper floors will only open a few inches. This is usually enough unless there is a window screen. I bring a few tools so, if needed, I can remove the window stop and open the window far enough to get the screen off. I have also used this setup as an indoor dipole in buildings without a lot of metal in the structure. The fishing pole is available from www.cabelas.com item number IB-115800, $25. Lou W7DZN ++++++++++++++++++ Date: Tue, 23 Oct 2001 04:21:56 -0700 From: lhlousek Subject: Re: [Elecraft] portable antenna for business trips Hi Tom, You wrote: <<...I have used an antenna consisting of 100' of #20 insulated wire, cut into two pieces of 30' and 70'....>> 70' is a little long to be hanging out a hotel window so, like you suggested, I experimented with single shorter wires (36') for use on 40 m and up. Although they work, the SWR gets pretty high on some bands which, in itself, is not a problem except for loss in the RG174 feedline. I find that the added 20 and 10 meter elements in my ribbon cable setup considerably ameliorate the SWR. Also, making the counter poise closer to 1/4-wave resonance eliminates, or at least reduces, the need for the 1:1 balun. I forgot to mention in the write up of my ribbon cable setup that I also have a wire with an alligator clip that I will sometimes use to connect the shield side at the BNC/binding-post adapter to a metal window frame or some other "ground" point in the hotel room. This sometimes helps received (and I presume transmitted) signal strength. It can also eliminate proximity effects when touching the rig. Lou W7DZN +++++++++++++++++++ Date: Tue, 23 Oct 2001 11:46:50 -0500 (EST) From: Dave Gingrich K9DC Subject: Re: [Elecraft] portable antenna for business trips I also carry two pieces of wire, one is 85 ft for the radiator and 60 ft for a counterpoise. With a BNC to UHF adapter I just banana plug the wires to the back of the radio. I have yet to find a frequency the tuner cannot match, 160 thru 10. I carry a sling shot in lieu of the 30 ft pole :) K9DC ++++++++++++++++++++ Date: Sat, 16 Mar 2002 21:45:44 -0000 From: Mike Bray To: "'qrp-l at lehigh.edu'" Subject: [122268] 20 Meter Half Square Antenna for QRP Portable Operation Hi, gang - About a week ago I uploaded our brand new Mich-A-Con Amateur Radio Club web site. Our club serves the South Central Upper Peninsula of Michigan and North Eastern Wisconsin. It is not a QRP club, but the web site has a QRP slant because its creator is an avid QRPer - me (Mike, KA1DDB) - hi hi!. Please visit the site and check out the article on the portable 20 meter half square antenna. Click on "Tips 'n Tales" on the menu. The URL for the web site is: http://www.qsl.net/ka1ddb/ 72, Mike Bray, KA1DDB QRPing in the Upper Peninsula of Michigan Grid: EN65cr Mikebray at uplogon.com +++++++++++++++++++++ Date: Fri, 22 Mar 2002 08:28:19 -0500 From: John Mckee To: "'qrp-l at lehigh.edu'" Subject: [122908] very good portable antenna comparison There is a very good real world comparison of several types of portable antennas on the hfpack website. It's sort of like a portable antenna "shoot out". Very well done. ++++++++++++++++++++++ Date: Fri, 22 Mar 2002 09:06:20 -0600 From: Chuck Carpenter To: khopper at uchicago.edu, qrp-l at lehigh.edu Subject: [122915] HF Pack Web and Group [was -- very good portable antenna comparison] Message-ID: <3.0.2.32.20020322090620.00839100 at mail.9plus.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" At 08:59 AM 03/22/2002 -0600, you wrote: >how about a link to the "hfpack" website? > >tnx, >de ken n9vv > Website http://www.hfpack.com/ Yahoo Group http://groups.yahoo.com/group/hfpack/ Chuck Carpenter, W5USJ, Point, Rains Co., TX - EM22cv, NETXQRP #1 QRP-ARCI #5422, QRP-L #1306, SOC #57, 6 Club #201, SMIRK #6275 Zombie #759, QRPp-I #115, COG #11, NETXQRP http://www.netxqrp.org ++++++++++++++++++ Date: Tue, 04 Jun 2002 17:01:06 -0700 From: Vic Rosenthal Organization: Transparent Software To: Trevor Day Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] easy simple portable antennas? Trevor Day wrote: > > Funnily enough, I have just been playing with a pole antenna (courtesy > W0KPH web site) just to prove to myself that its surely not possible to > radiate a decent signal on 20m using an antenna that is: > > contained within a tube of 2 inches diameter by 14 inches long, > fed with 4 feet of coax, > and leaning against the inside of my shack window!!! The link is http://www.qsl.net/w0kph/ if anyone's interested. What he's done, it seems to me, is make a dipole with a large amount of capacity between the (small) halves and resonate it with a coil. This dipole would be expected to have a very low radiation resistance, which he matches via a link. Probably the circulating current in the coil is quite high, which means that for reasonable efficiency it should be made of copper strap or tubing. I think I'll try it -- I'll use tubing for the coil and put a capacitor in series with the link to simplify tubing. If it works at all, its small size makes it interesting! 73, Vic, K2VCO Fresno CA ++++++++++++++++ Date: Tue, 4 Jun 2002 20:39:41 -0400 (EDT) From: kc4kgu at ENTERZONE.NET To: Vic Rosenthal Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] easy simple portable antennas? On Tue, 4 Jun 2002, Vic Rosenthal wrote: > Trevor Day wrote: > > > > Funnily enough, I have just been playing with a pole antenna (courtesy > > W0KPH web site) just to prove to myself that its surely not possible to > > radiate a decent signal on 20m using an antenna that is: > > > > contained within a tube of 2 inches diameter by 14 inches long, > > fed with 4 feet of coax, > > and leaning against the inside of my shack window!!! > > The link is http://www.qsl.net/w0kph/ if anyone's interested. What he's done, > it seems to me, is make a dipole with a large amount of capacity between the > (small) halves and resonate it with a coil. This dipole would be expected to > have a very low radiation resistance, which he matches via a link. Probably the > circulating current in the coil is quite high, which means that for reasonable > efficiency it should be made of copper strap or tubing. > > I think I'll try it -- I'll use tubing for the coil and put a capacitor in > series with the link to simplify tubing. If it works at all, its small size > makes it interesting! > > 73, > Vic, K2VCO > Fresno CA Vic, et all: I looked into this antenna a few weeks ago. From everything I can find with testing, it acts like any other short, fat dipole. IE; It is not a very efficient radiator. Sure, it will load up. That is a function os the loading coil and the capacitance between the two elements. It doesn't appear to radiate nearly as well as a *low* half-wave dipole though. Additionally, I think if you do some searching at google or whatever other search engine you desire on the EH and the CFA antennas (the EH design is apparently the prior work of Dr. Fathi Kabbary on his way to designing the CFA antenna) you'll find that there has been NO real-world testing done that shows results anywhere NEAR the claimed performance of either EH Antenna Systems or CFA Limited. Take a look at this article from Radio World Newspaper: http://www.rwonline.com/reference-room/special-report/rw-antenna3.shtml 73 de John - KC4KGU K2/100 #2490 +++++++++++++++++++++ Date: Wed, 05 Jun 2002 09:46:40 -0700 From: Phil Wheeler Organization: Outstanding To: ham_tech at juno.com Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] easy simple portable antennas? My favorite for quicky ops is an 84 ft wire radiator with a 17 ft counterpoise -- for use with a rig with a tuner. I think it's called a W3EMD or some such. Likely the dimensions could be halved for use on 40 and up. I also like my MP-1 for quick setup and 20/15 ops. For more serious portable ops (e.g., Field Day) a dipole is good and some use a loop on a 10 meter fiberblass mast. Best link I know of for antenna stuff is: http://www.cebik.com/radio.html 73, Phil ham_tech at juno.com wrote: >Hi, > >I know that their are other groups out there like hfpack that deal with >this subject. > >What multiband or single band antennas are available to be used with the >K2, for quick ops? > >I know about the Walkabout and the MP-1/-2. Are there any other antenna >brands cheaper than the MP-1? > >Send me some links. While I go and surf the enet.. for more info. > +++++++++++++++++ Reply-To: giantbug at earthlink.net From: "Mychael Morohovich / AA3WF" To: ham_tech at juno.com, "Phil Wheeler" Cc: elecraft at mailman.qth.net Subject: Re: [Elecraft] easy simple portable antennas? Date: Wed, 5 Jun 2002 12:56:53 -0400 Phil W7OX wrote, "My favorite for quicky ops is an 84 ft wire radiator with a 17 ft counterpoise -- for use with a rig with a tuner..." Ah, now you are talking about my favorite antenna, the W3EDP end fed wire! As described in the book Practical Wire Antennas by John D. Heyes G3BDQ, it is an omni-directional wire antenna 85 feet in length with a 17 foot counterpoise that is connected on some bands. With the exception of 15 meters, it loads easily on 80-10 meters with my KAT2. I do tune the 'poise with an MFJ Artificial Ground, but supposedly this is not necessary. The antenna requires no special earthing arrangements and can wend its way around a piece of property as needed. Mychael AA3WF K2#1025 +++++++++++++++++ From: "Stuart Rohre" To: "elecraft" , Subject: Re: [Elecraft] easy simple portable antennas? Date: Wed, 5 Jun 2002 15:44:11 -0500 A light weight dipole, or an up and outer, (one wire radiator, one wire counterpoise), are about the simplest most effective antennas you can build. IF you can put up a vertical with two gull wing radials, that too, will give great DX working. See Force 12 antenna web site on those. And a vertical dipole is free of needing radials, and should be considered if you have tall supports or trees in the field. 72, Stuart K5KVH ++++++++++++++++++