36 ft is 1/2 WL on 20M.
The W2PV Yagi Antenna Book shows that there is
virtually NO difference in gain for a 4, 5, or 6L Yagi
on a 1/2 WL boom. The gain vs. boom length curve
is NOT linear and if fact, has the smallest slope in
the region from .35 to .65 WL.
1/2 WL boom antennas offer little gain improvement
over 1/3 WL booms (24 ft on 20M), require more elements
to achieve good F/B and are therefore heavier and have
higher wind load. To achieve 2 dB more gain than a
3L or 4L 20 on a 24 ft boom, you need to go to 5L on
a 3/4 WL boom (56 ft). At 36 ft you would be lucky
to get 1 dB over a 24 ft boom, and probably less.
The Telrex 3L20 and HyGain 204BA have virtually
identical gain and F/B curves, peaking at 8.1 dBi
in the CW portion of the band and 8.4 dBi in the SSB
portion of the band. I would be surprised if the CC
4L20 or the 205BA gave much more than 9.1 dBi.
I'll let you do the modeling.
de Tom N4KG
On Thu, 1 Mar 2001 21:44:12 -0500 dan r goddar goddard <firstname.lastname@example.org>
> What do some of you believe is the best 20 meter, mono band, 36 foot
> antenna on the market. I just can't seem to decide on which one to
> As far as Ham Radio I am what some of you would a button pusher. So
> rely on the knowledge of those who are real pro's about these
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