I've had good luck with the Sencomm NMO.
SenComm NMO Mount Antenna | 700MHz 800MHz 900MHz Mobile Antenna
...which has done a better job of keeping things audible while I'm moving (sometimes pretty quick,) or when I'm in a densely populated area with lots of tall(ish) buildings and such.
It's never been closer than about 24 inches at least from the VHF transmit antenna, and I haven't had any issues while transmitting. I don't scan a lot of VHF anymore though, if that makes any difference in regards to that issue.
It does cause a bit of a sensitivity issue when I'm close to a site, but the built-in ATT on the scanner has done pretty good there honestly.
The Sencomm is NOT inconspicuous if that matters at your agency. It's pretty big, and prompts a few "what the h#ll is that, doppler RADAR?" comments from other officers / command staff.