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Looking to build a decent 6 mtr antenna ... probably a loop...
space no problem indoor out out... want to hit local repeater 50 miles away... ================================== The line-of-sight performance on a 50 mile path, at 50 MHz, with a Tx power of 50 watts and similarly polarised half-wave dipoles, is approx as follows - Tx to Rx transmission loss = 100 dB. 50-ohm Rx input volts = 500 micro-volts. Equivalent to S9 + 20 dB. Which is a very loud signal level. However, due to Earth curvature, at 50 MHz the radio horizon at ground level is only about 14 miles. And as Richard says, at least one of the Tx and Rx antennas must be elevated to more than 1250 feet above the other to achieve a line-of-sight condition without any high ground obstructions in between. Attenuation beyond the horizon increases rapidly due to diffraction. But you might just about make it with 50 watts and a 3-element vertical antenna. (A dipole with 1 reflector + 1 director.) (Or a dipole + 2 directors.) (Or you could try just 1 director.) Expect some fading depending on weather conditions. On the other hand, if you were lucky when you chose your QTH, you may come booming through. Enjoy yourself experimenting with a vertical antenna as high as possible above the roof tops. ---- Reg, G4FGQ |
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