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lets see, no tune, no atu, no switching, only coax.... not too many
restrictions here. i would recommend one of those super automatic no power no adjust antenna tuners that was sold briefly here in the states... until someone x-rayed the sealed enclosure and found it was nothing but a 50 ohm dummy load... worked relatively well with any length of wire over a wide frequency range with no adjustment. similar arrangements have been used for rhombics, adding a terminating resistor at the far end makes them much broader banded. the same thing is done on Beverage receive antennas, a resistor at the far end makes their pattern better. with this 'tuner' the idea is to swamp whatever odd impedance the wire antenna presented with the dummy load, at some frequencies you could get loss down to 3db or so, at others it was much higher, but you never had to tune anything and it was ready to go instantly on any frequency. the more acceptable answer is to get a rig with a built in tuner or get a small external tuner. "Bob Bob" wrote in message ... Hi All I want to get some ideas on how to feed my horiz 40M loop (NVIS) for harmonics of 7Mhz. It is sufficiently low to the ground that the feed Z is close to 50r (which makes 14Mhz - 100r, 21Mhz - 150r amd 28MHz - 200r) I realise that the radiation pattern may nit be desirable. Space is kind of limited here and stealth is important I want it to be "no tune/no ATU" and to avoid switching things in and out. It is currently fed directly with coax and a 1:1 ferrite balun. I cant use open wire feeder back to the TX (needing at least 10M of coax) Cheers Bob VK2YQA (bcnntp doesnt exist. If important use bcnoop) |
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