I played with a fan dipole back in the 1960's, and played and played and played trying to get a decent (less than 3:1) match to 50 ohm coax. Never was happy.
That experiment taught me the efficiency, ease and simplicity of a doublet* fed with open wire line. Working out the process of getting the open wire line into the shack wasn't nearly as difficult as trying to get the antenna to present a decent match to the coax, and it was a wonderfully efficient and effective all band antenna mounted at an "inverted V" with the apex at 50 feet. BTW, my doublet was 100 feet end-to-end and worked beautifully on 160 through 10 meters. Granted, at so close to the ground the radiation was mostly straight up on 160 but on that band I was mostly interested in working locals out to 100 miles or so. We had a lot of mobiles active on 160 back then as well as fixed stations. And none of the rude nonsense so often found on 75. Ron AC7AC *Wire fed at the center but not necessarily a "dipole" - i.e. 1/2 wavelength long - on any band. -----Original Message----- Subject: Re: [Elecraft] K2 + ATU + Loop antenna in the attic Alan, Sorry to hear about your lack of success with the fan dipoles. I have three of them - one for 80 and 40, another for 30, 17 and 12m, and yet another for 20, 15, and 10. They work very well. My "secrets" - space the wires for each band away from one another - my 80 and 40 antennas are at right angles to each other, so there is little of any interaction. The other two have the wires spaced about 1 foot apart using CPVC pipe with holes drilled in them (wires through the holes) to maintain the spacing. PVC would work too, but is heavier). The antennas do interact, so plan ahead, you will have to do some "cut and try" pruning. Tune the lowest band or resonance first, and then the next band higher in frequency. Trying it the other "way 'round" is an exercise in futility (been there, done that, and have the scars). I usually consider 3 bands on one feedline the limit of my patience, but this last weekend I helped a friend construct an antenna with 4 wires - 80, 40, 20, and 10 meters. It was a bit of a pain to tune, but it worked out well. Cut the wires at least 10% long and prune as required. One other point - do not use separate wires for bands that are close to the 3rd harmonic of another band - in other words, for HF, do not put a 30 meter radiator on a feedline that contains an 80 meter wire, and do not put a 15 meter wire on a feedline that also has a 40 meter wire. The lower band antenna may be usable on the 3rd harmonic (likely with a tuner), but trying to combine those two wires will result in even more frustration. 73, Don W3FPR On 4/15/2011 6:15 PM, Alan D. Wilcox wrote: > FWIW, see my fan antenna at > http://wilcoxengineering.com/projects/amateur-projects/39-fan-dipole > A bright idea that didn't work out so well! > > Cheers, Alan > > Alan D. Wilcox, W3DVX (K2-5373, K3-40) > ______________________________________________________________ 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 ______________________________________________________________ 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
