Topband: Effect of trees

[Gary and Kathleen Pearse]

It's that time of year when trees and temps become Topband topic. Propagation must be poor. 

Until the supporting tree blew down, my Inv-L for 160 required shortening of the L in the Fall when the supporting and surrounding trees froze along with the ground below. However, in mid-winter if the air temp rose above freezing for a spell (rare in Fairbanks, but…) I'd have to lengthen the same element, but rarely more than 6". The total length change between summer and winter was typically about 12-18" for 135' of insulated #12 stranded house wire at 1835 MHz. 

The 1/4 WL L paralleled a White Spruce tree for half its length, folded over the top, but the end was never near another tree for about 20-30'. Winds would alter the SWR slightly as the horizontal portion changed distance relative to the 8 tuned elevated radials and ground (dirt) beneath.

Without trees, some of us wouldn't have aerials.

73, Gary NL7Y