That's why I prefer an end-fed dipole to a Marconi antenna, even if I have to get creative to get wire up and in the clear.
The advantage is that the high impedance feed point at the end means very little current flows, so very little current need flow into the "ground" connection. Very little current means very little loss, since it's the ground resistance that bedevils efficiency in a Marconi (i.e. 1/4 wavelength or less) antenna. But that high impedance at the feed point is also the end fed dipole's downside. If near a half wave the impedance is usually beyond the matching range of most ATUs. However a small compromise in length will usually yield a "matchable" but high impedance. As one moves up in frequency that impedance will vary widely but will always be fairly high compared to a 1/4 wave radiator, and so offer much better efficiency for any given ground system. With the end fed dipole, an RF ground becomes more important to "keep RF out of the shack" by keeping RF voltages at the rig ground low rather than for efficiency. Ron AC7AC -----Original Message----- (For the record, I am also addressing some off-reflector extensions of this thread with a single post.) We are still talking about an end-fed antenna for 80-10 which presents unique problems. Trimming the horizontal length of up 30, out 30 for a good match will help a lot. But that will not address avoiding an up to 10 dB loss problem in the radial system that can make it perform like a wet noodle dipole... 73, Guy. ______________________________________________________________ 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
