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ferrymanr wrote:
Dan Remember that this has to be a 'stealth' antenna as I live dead center in the town with a lady councillor opposite, the town council office 75 yards away and town hall about 150 yards away. This rules out low loss copper pipe etc. Most of the small 'magnetic loop' antennas are intended for vertical use which would also stand out like a sore thumb here. The advantage of the wire loop is that many buildings here have wire around the roof to deter seagulls, that means my wire would not be conspicuous. When I modelled my 21' x 24' horizontal square loop with loading coils of about 90uH in each side leg I got a feed impedance of over 300 ohms but with -j5000 or thereabouts. The swr curved dipped nicely at 3.65 MHz to a manageable level if I used a 4:1 balun and 300 ohm line feed. I reasoned that as the natural loop resonance was between 20M band and 30M band I could link out the coils and operate those bands too, although that would means climbing up a ladder out of the rooflight rather more often than my old bones like. Richard (Dick) G4BBH In 'G' land what is the concern regarding public officials and radio antennas? Here in W/K land public officials and radio antennas are not a concern. Public safety issues are a matter of local building codes. Private contracts, known as CC&Rs, are a problem. |
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