Q John, KF6EOJ, asks, “I just recently completed a modification of a RadioShack FM antenna for 2 meter use, but I am a little confused about the issue of vertical vs. horizontal polarization. Two members of my local club say that for FM use I should use the antenna vertically polarized, which means modifying the antenna mounting holes, which I have already done. Is this true? I only have a FM H-T and I intend on using the antenna to increase my range.”
A When amateur 2-meter FM repeaters came along in the 70s they were used primarily for mobile communication. Horizontal mobile antennas proved cumbersome (remember the Halo?) and so vertical whips were the favored. Repeaters followed suit, using vertically polarized antennas as well. The penalty for a polarization mismatch (using horizontal polarization when the other station is using vertical, or vice versa) is a substantial signal loss.
So, the established custom among FM operators is to use vertically polarized antennas. If you want to communicate with other FM stations, choose vertical polarization. On the other hand, you should know that 2-meter SSB and CW operators use horizontal polarization—if you ever decide to give 2-meter DXing a try.
from QST May 2000
