At the club yesterday someone asked how a couple of local AM stations shared the same antenna. A quick look at a commercial VHF in-band high-band PMR transmitter combiner/duplexer rated for 50 Watts. And a much smaller, much wider bandwidth, out of band amateur "duplexer" that allows me to run my ancient FT736R VHF/UHF base station on one antenna. Out of band = one TX & RX on VHF, the other TX & RX on UHF. Compare the size of the in-band commercial VHF duplexer to the out of band VHF/UHF "duplexer".
