Any example were the 20m monoband yagi is 10dB better then the tri-band
antenna?
It seems very unlikely to me, Optibeam 21-3 and 5-20 are my examples.
73
Peter
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Tony
Sent: Sonntag, 15. Februar 2026 01:14
To: TowerTalk@contesting.com
Subject: [TowerTalk] Modeling Tri-Band Yagi Antennas
All:
I've noticed that most tri-band Yagi antennas that cover 20,15 and 10 meters
seem to have compromised F/B ratios on the 20-meter band. Some mid-sized
antennas have peak F/B ratios of only 15db on 20M, which isn't terrible, but
that figure is likely to get worse as you sweep across the band.
It must be a necessary trade-off in tri-band design since JK Antennas,
Optibeam and others lean towards the same compromise, which is a shame since
one would want that extra F/B performance on that band.
On average, a 20M mono-band Yagi outperforms the tri-band antenna by 10db or
more, which seems pretty substantial. I'm sure someone in the group has
modeled tri-band antennas like the mid-sized JK and Optibeam, and it would
be interesting to know what the criteria is for the 20M performance
trad-off.
Tony -K2MO
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