Proximity effect of 2 different vertical antennas
 

Hello again,

How close to my 20-meter mono-band vertical could
I put a 15-meter version of the same? I have a great
spot that's only about 10 feet away - will there be
negative interactions of the two? (Of course, it would
be nice if the sun had a few more spots!)

Thanks

Dave WB7AWK

Proximity effect of 2 different vertical antennas
 

"Zommbee" wrote in news:E-
:

Hello again,

How close to my 20-meter mono-band vertical could
I put a 15-meter version of the same? I have a great
spot that's only about 10 feet away - will there be
negative interactions of the two? (Of course, it would
be nice if the sun had a few more spots!)


Isn't that more like one antenna with two feedpoints. The 15m qw vertical
at 3m distance from the 20m antenna is just within the radian sphere, so
inside the near induction feild zone.

Owen

Proximity effect of 2 different vertical antennas
 

It depends.

This is an ideal problem for an antenna modeling program. You should be
able to get a pretty good answer from the free EZNEC demo available at
http://eznec.com.

Roy Lewallen, W7EL

Zommbee wrote:
Hello again,

How close to my 20-meter mono-band vertical could
I put a 15-meter version of the same? I have a great
spot that's only about 10 feet away - will there be
negative interactions of the two? (Of course, it would
be nice if the sun had a few more spots!)

Thanks

Dave WB7AWK

Proximity effect of 2 different vertical antennas
 

I suggest you put up the 15M and check how much the SWR on the 20M
antenna changes. I don't think it will change much at all. If the SWR
doesn't move then you don't have a problem.

Also, if you use a relay to disconnect the 15M antenna from it's coax
at the base of the antenna then you get a 42MHz resonant half wave
which will be even more out of the picture for your 20M antenna.

Bob AC7PN


Zommbee wrote:
Hello again,

How close to my 20-meter mono-band vertical could
I put a 15-meter version of the same? I have a great
spot that's only about 10 feet away - will there be
negative interactions of the two? (Of course, it would
be nice if the sun had a few more spots!)

Thanks

Dave WB7AWK