So far as is known, KDX Worldround Radio is the only Part 15 station that actually employs FM transmitters compliant within 15.239, well within a 100-foot range. The simple trick is that we use FM transmitters and radios in place of audio cables, to shuttle signals around our building and campus.
For KDX-FM, our main channel, we use a Decade GPL-32 FM Antenna in horizontal configuration. Of course reliable reception depends on a matching receive antenna at the FM tuner located at the control position.
But recently we lost our main EDM FM Transmitter to lightning, written about in other threads, and the backup Wholehouse 2.0 is designed to feed a vertical antenna.
To confound the situation there are other FM transmitters with various antenna patterns, so what we need at the FM receiver is an antenna capable of horizontal/vertical reception, perhaps circularly polarized.
Up until now the only circular antennas we've seen are designed for high power use, which makes them costly.
The public comment period opens now and will expire the day after Christmas.