[Elecraft] KAT500 Antenna Grounding

[Wes (N7WS)]

You've received some other advice/opinions about whether or not "ground" is 
"ground."

I won't expand on that but will address the real problem that you pose.  IMHO, 
whether or not you "ground", "short" or otherwise screw up the impedance of the 
driven element of the inactive antenna, there will be interaction between the 
two antennas.  Regardless of what you do to the inactive antenna's DE, all of 
the elements on both antennas are coupled.  To what extent, who knows?

This is true whenever there are two or more antennas in proximity Sometimes the 
effect is useful (stacked antennas); sometimes not. The only real way to know is 
to do some modeling.  You might see some effect upon the driven impedance of the 
active antenna, but this doesn't predict directivity effects.  One option might 
be to rotate one boom 90 degrees to the other.  Of course, now the boom of one 
antenna might upset the elements of the other.  Absent a science project, I 
suggest that you don't worry about it.

If you want to have some fun, however, you could ask Cushcraft to explain 
themselves.

Wes  N7WS

On Fri,5/8/2015 5:18 PM, David Ahrendts wrote:
>> I’m considering stacking the Cushcraft A503S 6M yagi with my MA5B mini-beam rather closely — like five-feet vertical separation (Rohn five-foot tripod on the roof in a tight lot). Cushcraft recommends using an antenna switch to ground the unused antenna since the two would react with each other at 17M. Both would be connected to the KAT500. So here’s the question: are the un-selected antennas out of the three on the KAT500 grounded  through the KAT500 or do they remain just unattached but active?