Antenna Install

Larry · Post by **Larry** » Thu Sep 05, 2002 3:10 am

I'm putting a 45 watt UHF with a 3db gain antenna and a 100 watt VHF with a quarter wave antenna in a pickup. Both antennas will be mounted centerline on the roof. For best performance and interferance issues, what would be the distance between each antenna ?

KG6EAQ · Post by **KG6EAQ** » Thu Sep 05, 2002 6:46 am

I'd aim for at least 23". 6" for the UHF, and 17" for the VHF... If you can put them farther... do it!

wa2zdy · Post by **wa2zdy** » Thu Sep 05, 2002 8:11 am

The rule of thumb is that an antenna have 1/4 wavelength of clear space around it to avoid interaction. So for hi band, that's about 19inches. At that distance, both your antennas will at least meet the standard rule of thumb. More of course is always better. My antennas on the trunk are 24 inches apart. One 5/8 wave putting out 135 watts on hi band, the other a UHF collinear from which I currently only run 5 watts. No signs of interaction at all.

So the above post from KG6EAQ with the recommendation of 23 inches is good, but the quarter waves do not need to be added together. The 19 inches is ok.

Good luck,