138 feet is a good length if you use a large series capacitor to tune out the
inductive reactance. I've used one for years, and the capacitor makes tuning
adjustments easy. Also, it raises the high current portion of the antenna
above the ground, and reduces ground losses. I'm currently using 4 elevated
radials (about a quarter wave straight, then at right angles), and have full
coverage from 1800-1900 by adjusting the capacitor for lowest SWR at about 1835.
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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