David, You're correct: with a high-Q loaded whip, especially on the low bands, position of the counterpoise relative to ground, structures and vegetation has a major impact. In some cases the counterpoise itself radiates more.
On top of that, the SWR can vary all over the map depending on counterpoise characteristics and terrain. This is why the AXE1 literature will specify that an ATU is required. Under all but ideal static conditions, SWR is unpredictable and the ATU will be required for transmit matching. 73, Wayne N6KR > On May 29, 2019, at 4:56 PM, David Gilbert <xda...@cis-broadband.com> wrote: > > > It's not the takeoff angle that makes the difference here. The takeoff angle > of a half wave vertical dipole over real ground is not much different than > the takeoff angle of a quarter wave (or shorter) vertical fed against a > ground plane or counterpoise. > > I'm pretty sure that what's really going on here is that as you make the > counterpoise wire more vertical the counterpoise is becoming the primary > radiating element The AX1 essentially becomes a loaded "counterpoise" for > the vertical trailing wire. I wouldn't be surprised if the counterpoise wire > does most of the radiating even if trailed across the ground, although much > of it would be lost to the lossy earth and the rest pointed upward. If we > were able to model the AX1 with the counterpoise we'd most likely see that > the integral of current as a function of length for the counterpoise wire > exceeds that of the AX1, and if the AX1 was vertical and the counterpoise > horizontal most of the radiated energy would be horizontally polarized. > Somebody could easily prove (or disprove) this with a short sense antenna and > a field strength meter. > > I suspect lots of people won't like this perspective, but there it is. > > 73, > Dave AB7E > > > > > On 5/29/2019 1:52 PM, Adam Goler wrote: >> I also anecdotally observed greater propagation with the counterpoise wire >> hanging vertically this past weekend. >> >> Intuitively, using a vertical counterpoise, as the "feedpoint" increases in >> height away from the ground plane of the Earth, the takeoff angle should >> decrease as the radiation pattern more and more resembles a free-space >> vertically oriented dipole field (picture a field shaped like a donut). >> >> >>> ---------------------------------------------------------------------- >>> >>> Message: 1 >>> Date: Tue, 28 May 2019 13:24:03 -0400 >>> From: Hank <h...@optilink.us> >>> To: VE2PID <ve2...@videotron.ca>, elecraft@mailman.qth.net >>> Subject: Re: [Elecraft] [AX1] Who has the AX1 antenna DX record? >>> Message-ID: <5bd0e4be75154c7f58e74eb7ee1b7...@optilink.us> >>> Content-Type: text/plain; charset=UTF-8 >>> >>> >>> Good info! >>> >>> I have noticed from operating in the field that I make more contacts if I >>> lay the counterpoise along the ground. ?I get better signal reports from >>> stations in the direction of the counterpoise. >>> >>> I noticed from operating this weekend at an overlook that with the >>> counterpoise over the side of the overlook going down hill at roughly 30 >>> degrees, my contacts were clustered farther away - again in the direction >>> of the counterpoise. >>> >>> I was operating on 20 and 17 with the AX1, KX3, SSB at 15 watts. >>> >>> Hank >>> K4HYJ >>> ? >>> ----- Original Message ----- >>> From: VE2PID (ve2...@videotron.ca) >>> Date: 05/28/19 11:30 >>> To: elecraft@mailman.qth.net >>> Subject: Re: [Elecraft] [AX1] Who has the AX1 antenna DX record? >>> >>> ... I used the AX1 as a test in WPX CW last weekend for only an hour on >>> a picnic table. No problem ...in that time I got 13 QSOs from FN45 >>> including FL. (10 Watts KX2, 13' counterpoise). >>> -- >>> After NEC simulations (0.005, 13 average ground) , we find how the gain >>> is maximized in the direction of the counterpoise. On 20 meters, if the >>> wire is horizontal at 4 feet height, the take-off angle is about 56 >>> degrees. But if the wire goes down from 4 feet to the ground (15 degrees >>> slope), the F/B is less but the take off angle is lower at 35 degrees >>> >>> (Image at https://i.imgur.com/XKPjM8T.jpg ) >>> >>> 73, Pierre VE2PID >>> >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> >> >> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
