Actually, it depends on what you want to listen to.
While Dubbin', is correct, the RadioShack 800mhz antenna is an excellent performer for 800 mhz scanning. For anything 800 mhz, conventional, trunked, P25, it excels.
BUT, I've found it's about the SAME as the 396T's stock duckie on VHF Hi band (150-159 mhz)
For UHF (400-460 mhz) it's performance is also marginal, and for aircraft band, (118-137 mhz), it's pretty much deaf to the world.
If you want increased VHF and UHF and aircraft reception, I reccomend the Diamond RH77CA antenna. It is a bit lengthy, but it's a awesome performer for those bands. Where the RH77CA lacks, the RS800 excels, and where the RS800 lacks, the Diamond 77CA' excels.