[TowerTalk] 204BA boom resonance, problem for 40 or not ?

[john at kk9a.com]

A Moxon antenna may react differently than a loaded element 40m beam. I
have never modeled a Moxon. I had very little interaction between a
shortened (loading coils) 2el 40m OptiBeam and a homebrew 4el 20m that
were 8-9 feet apart at my P40A station.

John KK9A


To:	<towertalk at contesting.com>
Subject: [TowerTalk] FW: 204BA boom resonance, problem for 40 or not ?
From:	"Matt" <maflukey at gmail.com>
Date:	Wed, 13 Aug 2014 23:09:32 -0500

Just want to echo John's comment about the 20m - 40m interactions.  I have a
pair of stacked 204's going up with a 40m Moxon.   I had to move the upper
204 about 15' away from the 40m to get the 20m interaction on the 40m
elements down to a somewhat reasonable level.   No predictable interaction
on the boom however.

Matt
KM5VI

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
john at kk9a.com
Sent: Wednesday, August 13, 2014 6:18 AM
To: towertalk at contesting.com
Cc: marko.l.myllymaki at gmail.com
Subject: Re: [TowerTalk] 204BA boom resonance, problem for 40 or not ?

The 204ba boom will have no effect on the 40m beam if parallel.  Regarding
15m, the linear loaded 40m beam is not resonant on 15m so there should not
be problems mounting it 11 feet above and parallel.  The only issue for it
would be the 20m beam 3 feet below which would severe interaction.
Turning the 15m beam 90 degrees may cause other issues depending on the boom
length. I model all of my antennas and mount them on the tower so that
interaction is minimized, I suggest that you do the same.

John KK9A