For portable/belt use (where you don't want a really long antenna) for VHF-High and UHF I would HIGHLY recommend the Comet MH-255. It's only 3" tall but I have found it performs extremely well on VHF-High and UHF on my BCD396XT.just mostly local stuff. in or around the 154 155 and 455 range stuff local sheriff went 154 digital so some thing in that area..
There are 2 versions, one with a BNC connector and one with a SMA. I prefer the BNC version because I change antennas frequently depending on whether I use the scanner at home (base antenna), in the vehicle (mobile antenna), or portable (HT antenna). The adapter takes the wear from frequently changing antennas, is easily replaced if needed, and the additional signal loss is negligible.The Remtronix REM-VU100S works just as good as the Diamond rh77ca and does not need a adapter as it is sma connector.