Exactly. Consider that the idea is to avoid RF currents being induced in the earth near the antenna. There are two ways to reduce those currents: more copper under the antenna and more separation between the antenna and the earth. So the higher the base of the vertical and radials are above the earth the less current will be induced in the lossy ground.
Almost all the studies about radials are to figure out the optimum tradeoff between cost and antenna efficiency for a given situation. As Don points out, it's important that the radials be fed in phase (connected to the same point) and arranged exactly opposite the vertical so the RF field created by one radial is cancelled by the opposite radial. Otherwise, the radial(s) will act like a random wire antenna very close to the earth. So, does a one-radial antenna work? Certainly since part of the RF power is still being radiated by the vertical itself. It's all a matter of arranging things to radiate more from the vertical and having less absorbed by the earth. 73, Ron AC7AC -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Barry LaZar Sent: Monday, July 01, 2013 3:06 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] OT- Radials for Vertical Antenna Mike, Tuned radials are really not needed in an elevated radial setup. You just put an ATU at the base of the vertical section and run 2-4 radials from the ground of the ATU. The only issue is making sure the antenna system is really high enough to be called raised. I would shoot for elevations in excess of 1/10 wavelength, and preferably a bit more. Impedance of the antenna is totally unimportant as the ATU takes care of making sure your transmitter "sees" a proper load. 73, Barry K3NDM ______________________________________________________________ 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
