[50mhz] Passive hilltop repeater for 50 MHz?
Bill W5WVO
w5wvo at cybermesa.net
Sun May 20 13:40:57 EDT 2007
Hams who inhabit the part of Albuquerque NM called the Northeast Heights have a severe handicap to overcome when working 6M sporadic-E: the Sandia Mountains to the east directly obscure half the compass. Take-off angles are limited to as high as ten degrees over much of this range, and this in turn limits the maximum single-hop distance to about half the upper limit (about 1400 miles) attainable with a flat 0-degree takeoff angle.
I've been thinking, just theoretically at this point, about passive repeaters -- basically two back-to-back antennas on top of the ridge with a short length of coax connecting the feedpoints together. I freely admit that the mathematics for computing how realistic this kind of idea is at 50 MHz is unknown to me. I know passive repeaters are used successfully in point-to-point microwave work, but the antenna gains involved there are extremely high. (Conversely, the path losses are greater.)
Does anybody have any experience or knowledge about this subject at VHF frequencies? Would the antennas required to make this actually useful just be really humungous (impractically so)?
Bill / W5WVO
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