Agree with Don 100%. Keep in mind that the power is divided between the counterpoise and the end fed antenna wire. The power divides according to their impedances; if the impedances are equal, you lose 3 dB (half of the power) in the counterpoise. So the idea is to have the counterpoise present the lowest impedance possible and the antenna present the highest impedance possible.
Usually the easiest first step is to raise the impedance the antenna presents. That's usually limited by the range of the tuner you are using to match the system to your transmitter but the ideal length is an electrical 1/2 wave of wire. Get a close as the tuner have can find a match. Next you lower the impedance of the counterpoise - the more wires the better although the advantage of more than 6 or 8 wires is pretty small. As Don noted, that also keeps the RF voltage at the rig low. Those are the ideals for an end fed wire. Most of us have to settle for something less for a variety of reasons. 73, Ron AC7AC -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Don Wilhelm Sent: Sunday, June 11, 2017 3:11 PM To: Gerry Miller; elecraft@mailman.qth.net Subject: Re: [Elecraft] Field use of Counerpiose Gerry, If your purpose for your "counterpoise" is simply to complete the antenna, then it does not make much difference whether it is grounded or not. But if its purpose is to keep RF off the enclosure of the rig, there is a difference. If it is 1/4 wavelength long, then it should not be grounded - just like any 1/4 wavelength wire, it is a low impedance point at the 'shack' end. OTOH, if it is 1/2 wavelength long, ground it to produce a low impedance at the 'shack end. A bit of study on antennas and feedline characteristics may be helpful. The 'counterpoise' acts like an antenna wire. 73, Don W3FPR On 6/11/2017 4:44 PM, Gerry Miller wrote: > > Does one ground to earth, the far end of an HF counterpoise or just let it float above ground at a field location? I had always believed it should not be grounded. ______________________________________________________________ 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 Message delivered to arch...@mail-archive.com
