commgrp@silver.bacs.indiana.edu (10/07/88)
>I have an antenna on VHF that might have the properties you're >looking for. It is from FAA surplus and is labeled circularly >polarized, so I guess it is. It's rather hard to describe, but >here goes. The elements are swastika shaped.... > >I assume the FAA wants this kind of antenna to receive equally well >from airplanes in all directions; and circularly polarized so it >doesn't care about the orientation of the (linearly polarized) antenna >in the plane. > >haynes@ucscc.ucsc.edu Circular polarization helps eliminate "mobile flutter" and other polarization-related effects. Another reason for the unusual shape of FAA antennas is to achieve omnidirectionality without a null zone directly overhead, like that produced by a simple vertical. -- Frank W9MKV reid@gold.bacs.indiana.edu