Absolutely. There's really only *one* "Zepp" antenna. It is a 1/2 wave radiator fed at the end with 1/4 wave of open wire line. Used on Zeppelins as a trailing wire antenna.
The problem with it is, if you want a low impedance at the rig end of the open wire line, is that it's only good at ONE frequency: that at which the feeder is 1/4 wave and the radiator is 1/2 wave. With that combination, there's little radiation from the feed line since it's still balanced. Although the antenna end of one side of the feeder connects to nothing, the other side is looking into the high impedance of the 1/2 wave wire so there's little imbalance in the feed line termination. Now, such an antenna can work FB on many frequencies, but the feed line will radiate since it's going to be very unbalanced and the feed point impedance at the rig might be anything, just as one would expect feeding a single wire antenna. Ron AC7AC -----Original Message----- From: Stephen W. Kercel [mailto:kerc...@suscom-maine.net] Sent: Saturday, May 16, 2009 7:38 PM To: wrco...@flash.net Cc: 'Elecraft Discussion List'; 'David Wilburn'; Ron D'Eau Claire Subject: Re: [Elecraft] OT - SteppIR Vertical and Elecraft Products Willis and others: There is a much cheaper trick than big coils and capacitors that ought to work, and could easily handle high power. Although I have never tried end feeding a half wave antenna, I have had great success in center feeding full wave antennas. The trick is to use an open wire feedline as a quarter wave transformer. I used the old fashioned "ladder line" with plastic spreaders and bare copper wire rated at 450 Ohms. Since the velocity factor is practically 1, I cut the length to the theoretical free space quarter wavelength. One end feeds the center of the antenna, and the other end goes to a 1:1 balun. It presents a very low SWR to 50 Ohm coax. I have done this on various bands with great success. I have not tried the "end fed Zepp" configuration implied by an end feeding scheme, but for the sake of this discussion, I have run a quick simulation. ______________________________________________________________ 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
