It is a matter of loss or lack of it. If you look at the takeoff patterns of a vertical antenna on a perfect ground and then with increasing loss, the pattern is modified to have increasing less energy on the horizon. However, this is the loss factor, not necessarily due to lack of resonance. As one removes the antenna network from direct ground, and substitutes radials, several things happen. IF, and that is a big IF, the amount of coupling to ground is maintained with non resonant radials or resonant radials are used, eff and match will remain . Example, a mag mount antenna or a ground plane vertical with three or four resonant radials works fine and any elevation. Just a point of thought.
Mel, K6KBE ________________________________ From: Steve Ellington <[email protected]> To: Guy Olinger K2AV <[email protected]>; Vic K2VCO <[email protected]> Cc: [email protected] Sent: Mon, December 20, 2010 3:44:28 PM Subject: Re: [Elecraft] Inverted-L (was OT: Vertical antenna) Guy: Very interesting.... Some of your comments were verified in a recent QST article. Mar 2010 - QST (Pg. 30) An Experimental Look at Ground Systems for HF Verticals The author experimented with resonant vs nonresonant radials on the ground and found performance improved when the radials were cut to electrical resonance vs just measuring them with a tape. Given this, it stands to reason that if the same radial field is used by a multiband vertical on a higher frequency, the high current point would be at some distance from the antenna's base thus reducing efficiency. Now here's the question.... Folks assume ground radials to be (non resonant) but that isn't the case. So what would be the best solution for a multiband antenna with ground radials? Well if we follow this idea, we would need multiple 1/4 wavelength radials for each HF band for best performance. My inverted L is 50' up and 150' out. I use a separate elevated counterpoise for each band. I've found that a ground rod and some buried radials have virtually no effect. I just use them for lightning protection. Steve N4LQ ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] 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:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
