bigpimp347 wrote:avoid a discone, all they are are un resonant lengths of wire you could use a coat hanger and pick up as well..
if you want VHF and UHF many ham antennas will work as these are designed to be resonant in these areas..
airband is just outside these bands but not by much and for receiving they work great..
X-30 or X-50 ideal for local 30 mile stuff..
X-200/300 for greater reception,
X-510 if you think gain answers all your questions and you have a good filtered front end..
me personally use an X-50 and even an X-300 get to hear some great distance without too move overload from local pagers and such..
Every length of wire/metal is resonant at various frequencies, so a discone
is a resonant antenna. Just not at a specified frequency like with a amateur radio antenna.
You are right about a amateur radio antenna being ideal if you want to listen to amateur bands. HOWEVER, the higher the gain, the narrower the band of low VSWR. So a high gain amateur radio antenna, is not as good on PMR, marine & airband for example as low gain amateur radio antenna, or a antenna designed for those bands.
The advantage with a well designed discone is that it is wide band antenna & offers a listener a good compromise over a series of band specific antennas. Although, to be fair a lot of antennas sold as discones are little more than a mobile whip antenna & some counterpoises & thus NOT a discone.