For a single band, there is an interesting old-time alternative called a single wire Windom. It is a horizontal halfwave with a single wire feedline connected to the horizontal wire off-center. For 20 the "dipole" part is 34 feet. The single wire feed is soldered to the horizontal at a point 12.5 feet from either end and drops to the ground.
The wire is fed against ground. The single wire exhibits a 400-450 ohm feed against ground, regardless of the height of the height of the horizontal under 3/4 wavelength. The vertical part radiates very little. A poor ground that would ruin a vertical's performance at 20-35 ohms feed Z will do OK at 400-450 feed Z. As in a single 17' radial wire just laid on the ground. You can feed it with a unun wound on a toroid with a 3:1 turns ratio. SWR on the low Z side easily matches 50 ohms well enough for coax or any antenna tuner, without having to endure the high voltages found on an endfed halfwave. It has the predictable performance of a good dipole, without the center insulator, and without the weight of a coax feed. If you use something like flex-weave for all the wires it can be wound up and carried around. 73, Guy. ----- Original Message ----- From: "Ron D'Eau Claire" <[EMAIL PROTECTED]> I think it must have been self defense by someone. Some time back I gave up using the term "dipole" because the current crop of Hams seems to think that means a center fed antenna of some arbitrary length, rather than an antenna that is exactly 1/2 wave long and which might be fed anywhere. So I gave up and started saying that I had a half wave antenna fed at the center, or at the end or off-center, etc. But, since I like others to understand what I'm saying, I avoid acronyms. I take it the coupler at: http://www.qsl.net/aa5tb/coupler.html Is for QRP only! At 50 watts or so, I used to get flash-over in a wide spaced air variable in that circuit. I used a large "Air Dux" coil with it. The voltages present at the end of a dipole are huge at any significant power level. I can't imagine the wire insulation on a toroid or a poly cap withstanding more than a few watts of RF there. Ron AC7AC _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
