[TowerTalk] Antennas for SO2R station

[Lux, Jim]

On 3/1/21 12:31 PM, john at kk9a.com wrote:
> I have never seen anyone put two SteppIRs on the same mast but the 7 ft
> separation is more than adequate for operating on two bands simultaneously.
> One of my homebrew 20m beams also has a commercial 40m beam mounted on the
> same boom and there is no interference except on the harmonic.

One potential threat I'll mention..

Say you're transmitting on antenna 1 on, say, 15 m, and using antenna 2 
on 20 m.

You then command antenna 2 to 10 m because of a band change. During the 
time that the antenna is changing the element lengths, there will be a 
short(TBD) time when the element lengths on antenna 2 are close to the 
element lengths on antenna 1, and the antenna to antenna coupling will 
greatly increase, especially if they're pointed the same direction.

(the pattern on antenna 1 will probably go wonky too, because of the new 
"parasitic elements" on the antenna)


If I did the analysis, and the levels looked scary from a receiver burn 
out standpoint, I'd arrange the switching logic so that Rigs don't 
connect to their antenna until they are in their final configuration. 
(and, also, that you have a lockout to prevent you from setting two 
antennas to the same band)

7 feet is a pretty small fraction of a wavelength (about 1/5th) , even 
on 10 meters.