Without modeling your exact configuration, I would say that this is likely
OK. I have modeled other 20m / coil loaded 40m beams and have seen few
interaction issues other then some loss of 40m F/B. If the 340N is linear
loaded it may react differently.
Interlaced yagis have elements designed to work together and in my opinion
they are not easy to design, even for just two bands.
73,
John KK9A
To: <towertalk@contesting.com>
Subject: [TowerTalk] 40 + 20m interaction.
From: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 16 Dec 2014 08:51:46 -0800
I don?t have software to model this scenario. Can I install a F-12 mag 520,
6.5 feet above a F12 340N, without the 2 x yagis interacting?
The 520 is a 5 el 30m yagi on a 35 ft boom. The 340N is a 3 el 40m yagi
also
on a 35 ft boom. I wont attempt it if the 20m yagi gain drops
a few db.
It still baffles me how some xmas tree monoband stacks require huge vertical
spacing to eliminate gain redux, screwed up FB, yet F-12, optibeam, JK
ants,
N6BT, all sell
interlaced arrays, covering 2++ bands on one boom. Im not talking about
forward stagger designs..but stuff like the C49-XR, etc, which is clearly
interlaced.
Tnx... Jim VE7RF
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