Reddit mentions of Tram 1199 Glass Mount All-Band Scanner Antenna

Trunked systems let a large number of users (say, police, fire and other city services) share a small set of frequencies rather than each entity requiring its own. Trunking-capable scanners let you follow/scan particular users of the trunked system rather than monitoring the individual frequencies. Since the frequencies are shared among all users, parking yourself on a single one would give you bits and pieces of lots of different conversations. Trunk-capable scanners came out, oh, about 10 years ago maybe. The systems themselves (and radios for listening) were all still analog.

A few years ago, many areas began using digitally trunked systems (most supporting a system called P25), which required another generation of scanners. Now, many localities are beginning to encrypt some public service communications (mostly law enforcement), and scanner-owners are going to generally be out of luck.

If you couldn't care less about those sorts of communications, then any analog scanner with Mil-air coverage (225-400) will suit your needs. If you are interested in the law enforcement stuff, you'll probably want to hang out in the RR forums for your area to see if encryption is coming for the stuff you want to hear.

To answer your question above regarding antennas: it depends on how far away you are from the stuff you want to hear. I'm close enough to what I want to hear, so the stock rubber duck antenna suffices. I installed a fairly inexpensive through-glass antenna for my truck, and use that with the handheld sometimes. A good antenna in the attic (or better still, outside) will make a world of difference if you're trying to pull in distant signals. Discones are good for this sort of thing - I had one years ago but somehow managed to lose it in a move. Do you need one? The radio will work without one, but you'll certainly hear more with a good one.