+++++++++++++++++++ Vertical antennas... Everyone has a story to tell ++++++++++++++++++ From: "Doug Person" To: Date: Fri, 11 Oct 2002 08:51:57 -0400 Subject: [Elecraft] Re: [Icom] Opinions re: HF Verticals? I can't agree with this. I have had a GAP Titan up for 6 years. It easily outperformed the R5 it replaced and is generally always as good or better than the ground-mounted homebrew verticals I have had for 20 and 40 meters (minimum of 16 radials each). But, for my money, the best darn commercial antenna I've ever owned is a W9INN 5 band dipole. It's only 60 feet long and covers 80, 40, 20, 15 and 10. On 80 meters it only covers 25KHz - but that's fine. I only care about the DX window. On 40 it covers about 200KHz. On 20 - 10 it's pretty much like any other dipole. And, yes, it eats the GAP's lunch any day of the week. Doug -- W4DXV ----- Original Message ----- From: "John Geiger" To: Sent: Thursday, October 10, 2002 10:40 PM Subject: Re: [Icom] Opinions re: HF Verticals? > Don't waste your money on a GAP vertical. They are > greatly overpriced, ugly as sin, and don't perform > better than any other vertical. Get a Hustler, or > Cushcraft, and go to it. Used to have a HyGain 40-10 > meter vertical, and it worked wonders ground mounted > with no radials. Also had a Cushcraft R4 for awhile. > It covered 20, 15, 12, and 10 meters, with no radials, > but the SWR changed whenever it rained. The hustlers > are rated as good as anything else to day, and less > than half the cost. Do hear good things about the > Butternut HF2V if you want it for 80/40 only > > 73s John NE0P > --- "George, W5YR" wrote: > > Nonsense . . . > > > > 73/72, George > > Amateur Radio W5YR - the Yellow Rose of Texas > > In the 57th year and it just keeps getting better! > > Fairview, TX 30 mi NE of Dallas in Collin county > > EM13qe > > K2 #489 Icom IC-765 #2349 Icom IC-756 PRO > > #2121 > > > > > > Dave Edwards wrote: > > > > > > Well, no vertical will work as well as your wire > > antenna, but I may put up > > > another vert. Probably another Hustler. The > > butternut is junk. I had one, > > > and gave it away! > > ---- > > Your Moderator: Dick Flanagan W6OLD, ++++++++++++++++ To: elecraft at mailman.qth.net Date: Sat, 12 Oct 2002 09:27:53 -0500 From: Jeremiah J McCarthy Subject: [Elecraft] Re: Elecraft digest, Vol 1 #303 - 29 msgs Bought a Cushcraft R-7000 new several years ago...The longevity and performance of this stack of pipe and the attitude of the manufacturer read like a horror story, and I won't risk a law suit talking about...Needless to say, Cushcraft couldn't sell me a rubber ducky now... Jerry McCarthy, wa2dkg K2 #2549 ----- Original Message ----- From: "John Geiger" To: Sent: Thursday, October 10, 2002 10:40 PM Subject: Re: [Icom] Opinions re: HF Verticals? > Don't waste your money on a GAP vertical. They are > greatly overpriced, ugly as sin, and don't perform > better than any other vertical. Get a Hustler, or > Cushcraft, and go to it. Used to have a HyGain 40-10 > meter vertical, and it worked wonders ground mounted > with no radials. Also had a Cushcraft R4 for awhile. > It covered 20, 15, 12, and 10 meters, with no radials, > but the SWR changed whenever it rained. The hustlers > are rated as good as anything else to day, and less > than half the cost. Do hear good things about the > Butternut HF2V if you want it for 80/40 only > > 73s John NE0P ++++++++++++++++ From: "Stuart Rohre" To: "Doug Person" , "elecraft" Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Date: Mon, 14 Oct 2002 14:04:00 -0500 I have had all type of antennas, even some most hams only dream about. (Rhombic, Vee beam 10 waves on 10m, 400 foot long wire, dipoles, quarter wave vertical, trap verticals like Cushcraft, Butternut, etc.) Now I have the Gap Titan for some 7 or 8 years. Best performing vertical over the R7, R5, Butternut, and some horizontal antennas. It is equal to my best dipole, and excels on DX. It has NO traps, only aluminum stubs so the parallel lines act as traps but without coil loss, or lumped capacitance. The only compromise stub is the 80m capacitor loaded one. It is an adequate performer on that band. If you could get the aluminum and insulators, sure you could build your own Titan, but your labor must be worth something. Much easier to get the kit. Aluminum tubing in many sizes is harder to come by these days. No one antenna is always the best, so I have a combination. One of the best all around performers for me have been very large horizontal loops, put up no more than 20 feet high! With one 849 feet around, we worked Indonesia at QRP phone last Field Day. IDEZ antennas I developed are also excellent performers, but require a transmatch as does the large loops for all band use. (Inverted vee Double Extended Zepps). We use open wire feeders for those big wires. 72, Stuart K5KVH +++++++++++++++ From: "Mike McCoy" To: "Elecraft" Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Date: Mon, 14 Oct 2002 19:01:10 -0500 Well I broke down and ordered a Force 12 Sigma GT5 (no-trap/no radial vertical dipole) today. Since I have no horizontal space for a dipole I've been investigating verticals for a while. The thing that has put me off (aside from the need to plant radials) is that for virtually every vertical manufacturer it seems 1/2 of owners love em and the other 1/2 can't get rid of them fast enough. Except for Force 12... I haven't heard one person say anything (really) negative about Force 12 antennas. And apparently they can't keep the Sigma 5 in stock (backordered 3-4 weeks). And here's a very interesting new antenna from Force 12 just now available, a 16' 40-10 vertical dipole: http://force12inc.com/sigma40XKinfo-001.htm Not bad for $249... Mike - AD5IU ----- Original Message ----- From: "Stuart Rohre" To: "Doug Person" ; "elecraft" Sent: Monday, October 14, 2002 2:04 PM Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? > I have had all type of antennas, even some most hams only dream about. > (Rhombic, Vee beam 10 waves on 10m, 400 foot long wire, dipoles, quarter > wave vertical, trap verticals like Cushcraft, Butternut, etc.) -- snip -- ++++++++++++++++ Date: Mon, 14 Oct 2002 19:53:25 -0700 From: Vic Rosenthal Organization: Transparent Software To: Mike McCoy Cc: Elecraft Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Mike McCoy wrote: > > And here's a very interesting new antenna from Force 12 just now available, > a 16' 40-10 vertical dipole: > > http://force12inc.com/sigma40XKinfo-001.htm > > Not bad for $249... It's a very nice antenna, but keep in mind that it can be set up for any ONE band from 5-30 MHz -- it is NOT a multiband antenna. Vic K2VCO ++++++++++++++++++ Date: Mon, 14 Oct 2002 23:23:16 -0400 To: Vic Rosenthal , Mike McCoy From: Hank Kohl Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Cc: Elecraft At 10/14/2002 07:53 PM -0700, Vic Rosenthal wrote: >Mike McCoy wrote: > > > > And here's a very interesting new antenna from Force 12 just now available, > > a 16' 40-10 vertical dipole: > > > > http://force12inc.com/sigma40XKinfo-001.htm > > > > Not bad for $249... > >It's a very nice antenna, but keep in mind that it can be set up for any ONE >band from 5-30 MHz -- it is NOT a multiband antenna. True it's not automatic or remotely switched, but it is multi-band with manual, physical switching. The Sigma5 is 20-17-15-12-10M with relay control to change bands. A friend of mine used a couple of these on his last trip to the Pacific and said they performed great. Not bad for $349 and very portable. 73 Hank K8DD +++++++++++++++ From: "Dave Larson" To: Cc: Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Date: Tue, 15 Oct 2002 08:19:22 -0400 As the owner and user of one of the Sigma 5's that Hank refers to, let me say that it is an outstanding antenna for dx work. It does, however, have a low angle of radiation and would not be an antenna for emergency work for that reason. Ted, K8AQM, and I made 7500 Q's in the 9 days we were in 5W0 using the 2 Sigma 5 antennas on 20 meters and up. We worked a large number of QRP stations on RTTY, CW and SSB. We received many comments about how loud we were. WE tuned the Sigma's so that we had a low SWR from 14.025 to 14.260 and stayed well below the 2:1 SWR given in the specs. I've made a comparison from home (Michigan) comparing the Sigma to a R8 vertical and the Sigma is the winner on DX but the R8 beats it for stateside. The Sigma 5 will be going with me on the next DXpedition. Dave, K8AA 5W0DL K2/100 #2657 ++++++++++++++++ From: "Stuart Rohre" To: "Mike McCoy" , "elecraft" Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Date: Tue, 15 Oct 2002 13:48:27 -0500 Tom Schiller at Force 12 is a good antenna guru. He has done his homework, and the vertical half wave dipole is an excellent vertical antenna, with the usual advantage of low angle lobes for good DX work. No vertical will do some things a horizontal will, nor will a horizontal do all things a vertical can do. Sometimes one or the other will do what is normally associated with the other. Close in working is not the main forte of verticals, but can be done when conditions are right with good signal reports. It can hear just fine, it is the strength of the close in transmit that is down since most of the energy is going out in the low angle lobes to DX locations. That said, the loaded shortened half wave vertical, with loading coils to match it can also give a fine accounting. As the books will tell you, and W4RNL has extensively modeled, and written; a dipole can be shortened to 60 per cent of normal length and still be highly efficient. Thus, Force 12 has taken basic physics and made very effective antennas for 40 to 10 on the vertical center feed principle. Since there are two halves to the antenna no radial system is needed. Any ground enhancement would have to come in the far field, usually at 2 to 5 wavelengths away, well beyond the usual ham's control. The people who do not like verticals either do not understand they are superior for low angle DX, and want them to do close in work all the time, or they do not have an adequate ground system or radial system if using "half an antenna"-- the quarter wave vertical and its loaded equivalents. There are some loaded quarter wave type antennas, that are much less than 60 per cent of full length, where efficiency remains high on the dipole types. The shortened verticals will work sometimes much better than an excessively low dipole. They have many advantages some are: little real estate required above ground, and easily hidden behind the house in the back yard. For antenna challenged hams they may be a viable solution. Force 12 is one of the few antenna companies whose designers regularly partake of DX -peditions and test out their designs in real world operations. Look at their web page for excellent troubleshooting information on any antenna as well. Although I do not own one at present, we have bought them for research work and find they do things as advertised. Many personal visits with Tom have also shown me he knows antennas! 72, Stuart K5KVH +++++++++++++++ From: "Stuart Rohre" To: "Mike McCoy" , Subject: Re: [Elecraft] HF Verticals? Date: Tue, 15 Oct 2002 14:09:56 -0500 And the other great web site for antennas basics and applications: L. B. Cebik's W4RNL continuing efforts at www.cebik.com 72, Stuart K5KVH ++++++++++++++++ Date: Tue, 15 Oct 2002 13:03:58 -0700 From: Vic Rosenthal Organization: Transparent Software To: Elecraft Subject: Re: [Elecraft] Re: [Icom] Opinions re: HF Verticals? Stuart Rohre wrote: > The people who do not like verticals either do not understand they are > superior for low angle DX, and want them to do close in work all the time, Over poor or just OK ground, even a vertical with a good radial system will compare poorly for DX to a horizontal dipole at more than a half-wavelength above ground for DX. The theoretical pattern is subject to a big suck-in at low angles caused by poor ground in the Fresnel zone a few wl from the antenna. So above 7 MHz (wl/2 = 70 ft) most of us can build a horizontal antenna that is more effective than an excellent vertical (like the Force-12 verticals). > or they do not have an adequate ground system or radial system if using > "half an antenna"-- the quarter wave vertical and its loaded equivalents. Even a vertical dipole or a monopole with 120 radials behaves as above. By the way, Stuart, I don't know where you are located but some areas in Texas have very high ground conductivity and these places are, so to speak, fertile ground for verticals! 73 Vic K2VCO +++++++++++++ From: "Stuart Rohre" To: "Mike McCoy" , "Steve Lawrence" Cc: Subject: Re: [Elecraft] HF Verticals? Date: Fri, 18 Oct 2002 15:14:17 -0500 Steve and the group, be careful in trying to compare ANY vertical to a dipole. They are really for differing applications. The dipole at 30 feet high, will work more close in stations locals, and short hop, say on 40m. On the bands 20m and up it will be good for DX in the two directions a dipole works broadside to the wire. It will be of limited utility at 30 feet for 80m, even if long enough there. The vertical is an omnidirectional antenna. If there is DX in any direction, it should hear and work it, as it favors low take off angles if its vertical dimension is a substantial fraction of a half wave or quarter wave at the band in use. IF a quarter wave type, it HAS to have SOMETHING to replace the other missing half of the antenna. The near half wave verticals can do that, without added radials, or ground screen in near field below. The quarter wave must have help be it radials, elevated or ground, or a plane or screen. The vertical is mainly a low angle radiator, but can under conditions all the time work close in stations but perhaps without as strong a signal as a horizontal. That is because the horizontal wastes some signal in terms of DX working with overhead radiation, but that same overhead lobe, is what gives high angle ability to reach close in stations with good signals. The vertical has little radiation off its end, if of the classic type, much as the dipole has little radiation off its end. In the case of the vertical, you lose ONLY the overhead direction, while the dipole loses two directions off the ends. The real answer is you need both a dipole and a vertical for a good combination of high angle capability for in state, or close state work, and low band work, and the vertical for DX. The vertical, if a good one, is the cheapest DX antenna other than a very large Vee Beam, or Horizontal Loop, which few have the real estate to put up save perhaps for 10m. Those need to be 2 waves at least, and that would be 64 feet at 10m, doable on a city lot, but barely. If you must have low profile, a vertical behind the privacy fence and behind the house, will have lowest profile from the street, unless you have enough trees to hide a horizontal or loop. Don't give up on having an inverted Vee, if you still need stealth antennas. I know a ham who hung one within a large tree he had in back yard, and it was with such smaller wire and insulators that it was not seen from outside his yard, but worked well on the lower bands where Inv. Vees are commonly used. Insulators for those can be small pvc pipe couplings, or sections, or small vitamin plastic bottles. If you could only have one antenna, and it most be low profile, I would first go with a vertical. IF you could get a horizontal up half wave high, then that would be my first choice. At 30 feet, I would go with the vertical. A 30 foot vertical will give a good account of itself on 40m and up, if made for all those bands. 73, Stuart K5KVH +++++++++++++++ To: elecraft at mailman.qth.net Date: Fri, 18 Oct 2002 14:04:55 -0700 Subject: Re: [Elecraft] HF Verticals? From: k6se at juno.com Stuart, K5KVH wrote: "IF a quarter wave type, it HAS to have SOMETHING to replace the other missing half of the antenna. The near half wave verticals can do that, without added radials, or ground screen in near field below. The quarter wave must have help be it radials, elevated or ground, or a plane or screen." ========== While I agree with the rest of Stuart's post, I must take exception with his statement about 1/2-wave verticals (either dipoles or end-fed) and elevated radials. One of the most common misconceptions is that a low 1/2-wave vertical does not need radials. If a good radial system is not placed on the ground below this antenna, the same amount of energy heats up (is lost in) the ground just as much as it would with a 1/4-wave vertical. The only way around the ground loss problem is to make the center of the vertical at least 1/2-wave above ground, and preferably much higher. The same is true about a 1/4-wave vertical with elevated radials (unless there are as many radials as there would be if the vertical was ground-mounted). Many hams on 160m use only 4 elevated radials 10 feet high or less, thinking it will work as good as an on-ground system with 60 radials. 10 feet is less than 0.02 wavelength on 160m, so those 4 radials act the same as if they were on the ground or buried, therefore the same ground losses apply for the "elevated" system, so the ham using a low, elevated radial system is disappointed in the results compared to those who use extensive ground radial sustems under their verticals. Although the antenna will work, most of the power is lost in the ground. This has been proven by far-field field strength measurements by others who have investigated on-ground versus elevated radial systems. For a 4-radial elevated system to be any good, it must be *at least* 1/4-wave high. Even at that height the antenna efficiency suffers due to ground loss. Ground screens have also been investigated. While they are ok if they extend away from the base of the vertical as far as an extensive radial system would, the radials are still better (and far less expensive). 73, de Earl, K6SE +++++++++++++++ From: "Stuart Rohre" To: , Subject: Re: [Elecraft] HF Verticals? Date: Fri, 18 Oct 2002 16:43:56 -0500 Thanks for the comments Earl. I got to typing too fast and should have included the following: I should have clarified that extensive modeling work by L. B. Cebik, W4RNL, and published by him at his www.cebik.com web site, shows that CENTER FED vertical dipoles, at the heights he modeled, do not show much effect from the addition of ground screen under them. I refer those with questions to L. B.'s excellent web comments upon this point. He has been right on with all his modeling, and I know from personal correspondence, he checks things with all the available programs, even the professional ones, not ordinarily available to hams. The bottom fed half wave, as Earl reports, certainly might suffer earth loss. I have not seen modeling for this case as yet. (End feed, with and without added ground under it). I have not been worried about small improvements less than a dB or 2, but certainly, some might feel those should be pursued. Most antennas would benefit by improved RF earth in the Fresnel Zone, but that is out of hams control in most locations, being some 2 to 5 wave lengths away from the antenna. But, this area is the one you can somewhat control by locating your antenna on the edge or top of a high location. vertical dipoles, (center fed), are an underexplored resource available to hams for 20m and up, and in the capacitance hat loaded forms now being offered, for 40m and up. My work with 5 band models has been most encouraging, and our lab has acquired some more from Force 12 for our HF experiments. I hope to build an all band model without loading coils myself to see if there is good improvement from that effort. I would hope to use parallel vertical dipoles supported by the one for the lowest band. Sleeve feed would be possible it seems with such an arrangement. That works well in beams and horizontal antennas thus should be a natural for the home made vertical. 73, Stuart K5KVH ++++++++++++++++ To: elecraft at mailman.qth.net Date: Fri, 18 Oct 2002 16:05:11 -0700 Subject: Re: [Elecraft] HF Verticals? From: k6se at juno.com Stuart, K5KVH wrote: "I have not been worried about small improvements less than a dB or 2, but certainly, some might feel those should be pursued." ========== Dean Straw (N6BV), who is ARRL's antenna guru, used NEC-4 (which can model buried radials) to compare the efficiency of various radial systems. His modeling showed that for a system of four 1/4-wave radials on 80m in or over "very poor" ground, about 4.75 dB of the power being applied to the antenna was dissipated in ground losses. Increasing to sixty-four 1/2-wave radials reduced the ground loss to about 1.50 dB. Over "average" ground, the 4 radials resulted in about 1.75 dB loss, and 64 radials had about 1.0 dB loss. The moral of this story is that you should pick a site with high soil conductivity for your vertical (where the number of radials is less important). Now we know why maritime mobiles with their salt water ground are so loud on the low bands. And it explains why a balloon-supported 160m vertical over a moist salt lake bed easily outperforms mountain-top 4-square vertical arrays (which dispells the fallacy that mountaintop QTH's are better for HF or MF DXing). 73, de Earl, K6SE ++++++++++++++ From: "Stuart Rohre" To: , Subject: Re: [Elecraft] HF Verticals? Date: Fri, 18 Oct 2002 19:27:18 -0500 Earl, there have been a number of papers on improved radio locations from operating from elevated ground. I wish I could remember the paper, but there is one I have seen with the ray traces to show the signals improvement. The signal can go from the antenna toward ground, but if on a hill, the reflection happens at lower ground and they get a nice low angle of takeoff on the reflection, lower than the flat ground case. Locally, NT5C has had much good success from his hill, compared to my valley location. The paper I remember, had both operating measurements and modeling of the paths, supported by the operational experience. Sorry I cannot remember where I saw it, but might be QST or CQ, or QEX, even Communications Quarterly. We see the same thing in sonar measurements off reflections in a depression below the sonar source. It is proven Physics. 73, Stuart K5KVH ++++++++++++++ From: "Stuart Rohre" To: "Jason Hissong" , Subject: Re: [Elecraft] HF Verticals? Date: Fri, 18 Oct 2002 19:38:25 -0500 With the Hexbeam, which as I understand is a varient of the Moxon Rectangle, or the VK2BQW, you have a potential low angle radiator with gain, and front to back ratio. No reason to add vertical, unless Hex does not live up to its billing. The vertical would not have gain, unless, (and you could) phase two verticals. Make one a director, and lightweight material, and walk it around to various locations supporting it with a T fence post and short mast, (elevating the fed vertical), and ergo a vertical beam. Why not just make a dipole for the 70 foot space, and mount it below (or beside), the Windom a few feet, and droop both ends, so it can be closer to full length half wave dipole for 80m? It will also load on 160 m with low loss if fed with 450 ohm ladder line. A dipole can be shortened to 60 per cent and still work with nearly full efficiency. Transmatch can make it work on lowest band. That way, you could get 110 foot dipole in 70 foot length. A full size 80m is only about 130 foot. Make it of no. 14 solid pvc insulated wire from Home Depot. Please let us know how the Hexbeam works re DX. 73, Stuart K5KVH Orginal Message: From: "Jason Hissong" To: Subject: Re: [Elecraft] HF Verticals? Date: Fri, 18 Oct 2002 20:11:02 -0400 I have been following this thread with some interest. I just bought a Hexbeam and will be getting a WindomHSQ. The Hexbeam will be up about 32' (I could go higher if I got the 26' roof mounted tower instead.) The Windom will be mounted at about the 30' mark (center supported). That way, I could get the benefits of the beam, local stuff with the dipole. I guess my question is, would getting a vertical also be beneficial? I have no means to get on 80 and 160 with that antenna configuration. I have about 70 feet between two trees. Both of which I may be able to get a flat top at 30 feet. Was thinking about the Bencher (Butternut) 2 band antenna with the 30 and 160 meter kits. Thanks! Jason Hissong N8XE ++++++++++++ Reply-To: From: "Ron D'Eau Claire" To: Subject: RE: [Elecraft] HF Verticals? Date: Fri, 18 Oct 2002 18:30:24 -0700 Earl, there have been a number of papers on improved radio locations from operating from elevated ground. I wish I could remember the paper, but there is one I have seen with the ray traces to show the signals improvement. 73, Stuart K5KVH ---------------------- In the Ham literature, there is an excellent article by Al Christman, KB8I, "Elevated Vertical Antenna Systems, published in the August, 1988 QST. That article also appeared in the ARRL publication, "Vertical Antenna Classics". This article is a Ham-oriented version of Christman's "Vertical Monopoles with Elevated Ground Systems," published in the Proceedings of the Third Annual Review of Progress in Applied Computational Electrodynamics by the Naval Postgraduate School, Monterey, CA, March 1987. H. L. Ley, Jr., N3CDR, did some very enlightening and interesting experiments comparing a short loaded counterpoise to an elevated ground system. He published his findings in "A Multiband Loaded Counterpoise for Vertical Antennas" that appeared in "The ARRL Antenna Compendium, Vol. 2" as well as in "Vertical Antenna Classics". Ron AC7AC K2 # 1289 +++++++++++++++++ To: rondec at easystreet.com, elecraft at mailman.qth.net Date: Fri, 18 Oct 2002 19:50:56 -0700 Subject: Re: [Elecraft] HF Verticals? From: k6se at juno.com Ron, AC7AC wrote: "In the Ham literature, there is an excellent article by Al Christman, KB8I, 'Elevated Vertical Antenna Systems', published in the August, 1988 QST." ========== Although KB8I is much respected, especially for his papers on phasing systems he developed for vertical antenna arrays, his work on elevated radial systems has been much discussed and questioned on the topband reflector. I mentioned in an earlier post that far-field field strength tests were done to end the debate on whether elevated radials were any better than buried radials. These tests were done by Tom Rauch, W8JI, who is one of our most knowledgable AM BC engineers. Knowing Tom, I'm sure that the tests were very well controlled and honest. Anyway, the field strength measurements taken at a mile or so away from the antenna in all directions, proved that elevated radials 10' high have no advantage over the same amount of buried radials. 73, de Earl, K6SE +++++++++++++++++ Date: Sat, 19 Oct 2002 08:15:45 -0400 To: From: Charles Greene Subject: RE: [Elecraft] HF Verticals? Cc: Hi All, Anyone contemplating the use of elevated radials should read the article by Dick Weber K5IU in Spring 1997 Communications Quarterly. Basically, Dick points out that 1/4 wavelength is the length to be avoided in elevated radials. This is because the impedance of resonant radials is zero, and the current distribution in the radials is very uneven and one radial hogs the current, drastically modifying the radiation pattern. He recommends using radials of less than 60 degrees or more than 120 degrees to increase the impedance of the radials so that a minor variation in the impedance of one radial will not affect the current distribution. Moxon covers the subject of elevated radials and recommends using shortened radials with a common loading coil to tune them to resonance. He also states that the resonance length of 1/4 is the one to be avoided. Other authors such as ON4UN recommend the same approach. I have experimented with non resonance radials by making the radials short and increasing the length of the vertical element to tune the system to resonance, and by making the radials long and the vertical element short to tune the system to resonance. The reactance of the non resonant radials cancels the reactance of the vertical element so that the entire system is resonant. This may be covered in the literature somewhere but I haven't found it. I got the idea from KC1SD who has been using it for years for 20 and 40 meter portable elevated radial verticals for field day. The principle here is the same principal in use with an off-center-fed horizontal antenna to a lesser degree. I have found you can't depart very far from the resonant length of either the vertical or radial element. The antenna resistance at resonance with short radials and a long vertical is greater than 36 ohms, and the resistance of the antenna with long radials and a shortened vertical element is less than 36 ohms. I have found this in the modelling and verified it with the actual antenna. Modelling shows the longer vertical element has a fraction of a dB more gain than the shorter vertical element, as to be expected. I have modelled the system using an inductance to tune short radials as recommended by Moxon, and have also modelled placing the inductor half way up the vertical element to tune the system. The latter configuration shows more gain (less loss) than the former for the same reasons that a mid-loaded vertical has less loss than a base loaded vertical. KC1SD and I have been using 2 elevated radials. The model shows they work as well as a system with more. The model shows a surprisingly asymmetrical pattern with only two elevated radials, which of course is an advantage for portables. My current project uses two long radials and a shortened vertical element. The radial were elevated only 1' here at home, but they were on the edge of a 8' sea wall on the shore of Narragansett Bay. At the special event site, I used the same vertical but elevated the radial to 7.5' so that people could walk under them. There was a good bit of retuning required from the antenna with 1' elevated and the 7.5' elevated radials. At 06:30 PM 10/18/2002 -0700, Ron D'Eau Claire wrote: >In the Ham literature, there is an excellent article by Al Christman, >KB8I, "Elevated Vertical Antenna Systems, published in the August, 1988 >QST. That article also appeared in the ARRL publication, "Vertical >Antenna Classics". This article is a Ham-oriented version of Christman's >"Vertical Monopoles with Elevated Ground Systems," published in the >Proceedings of the Third Annual Review of Progress in Applied >Computational Electrodynamics by the Naval Postgraduate School, >Monterey, CA, March 1987. +++++++++++++++++++ From: "Stuart Rohre" To: "Paul Womble" , Subject: Re: [Elecraft] HF Verticals? Date: Mon, 21 Oct 2002 15:26:13 -0500 One should never be too quick to say absolutes about radio propagation and types of launching systems for the waves. The pioneering work now being done by Dr. Robert L. Rogers on the FLEX antenna, which does use resonant elements, but confined to much smaller volume than their total length, has shown much promise for efficient tho small antennas. The type of Earth under an antenna can have many interactive effects. Better ground may require more radials to avoid having currents lost to earth, than those radials lying on poor ground. There seems to be evidence that half wave antennas should operate virtually independent of earth, but field strength measurements are also needed to see if adding radials under them does anything. The complication is defining the earth under the antenna adequately, as most practical installations are over non homogeneous earth conditions. Near field objects in the practical ham installation may greatly affect and alter what otherwise would be optimum ways of using radials, ground reflectors, etc. My own grounding tests in tropical Malaysia, and desert West Texas undoubtedly are different from those in Northern U. S. The literature on the use of quads in overseas locations often reports excellent results at low heights, while there has been less favorable reports on quad vs. Yagi tests on towers in U.S. About all we can say absolutely is there is no one antenna "best" for all locations and conditions. Rarely have hams considered they should match their antenna choice to local earth under the proposed antenna, but my own experiments show I should have considered that earth, and characterized it before picking some antennas I have used. 72, Stuart K5KVH +++++++++++++++++