[TenTec] OCF: 3 1/2 wave collinear

[M.Wood]

I thought some of you interested in OCF antennas (that fit your suburban lot) 
might like to know of a solution that has worked well for me: A collinear 
dipole constructed of 3 1/2 wave elements. The "long" side has 2 half-waves 
joined by a 1/4 wave phasing loop, the "short" side is 1/2 wave. The antenna 
is cut for 30m, and is somewhere around 138' long (I cut and pasted until I 
got it right so I can't really say exactly how long). It is about 47' high 
from center support, and droops slightly toward the ends. Feed is ladder 
line, about 97' long or so, to a balanced tuner (not a matchbox). A W2DU 
choke balun is placed between transceiver and tuner. (References: Wire 
Antenna Classics, Antenna Book.)

The antenna tunes up on all bands from 15m to 80m; the tuner can make a 1/1 
match on all except 17m and 40m where there is about 1.1-1.4 swr according to 
Autek meter. Output power is about 70w according to Autek meter, barefoot 
OmniD. Interestingly, there seems to be some kind of resonance for 80/75 
meters such that output power appears to be boosted over other bands.

Mike K2CSJ