One of the most enjoyable aspects of scanning is finding a new frequency, or finding out who is using a frequency. You can learn a lot by knowing about antennas. If you know what type of antenna to use, or you recognize an antenna on a vehicle or building you can close in on matching a frequency with a user.
The lower a frequency, the longer the antenna will be to transmit or receive on that frequency. In other words, bigger isn't always better. High Frequency (HF) frequencies are below 30MHz and will be very large, like a car CB (Citizen's Band is in the 27MHz area) antenna which is 100 inches long. On the other end of the scanable spectrum, 800MHz frequencies used by business, public safety, and cellular, to name a few, use antennas from 3 inches to 12 inches or so. In between are UHF in the 450MHz to 500MHz range with antennas about 6 inches long as a simple whip (no loading coils, like a regular broadcast radio antenna) or up to 36 inches or so with a band or loading coil in the middle. VHF-LO, which includes CB, may also be as short as 36 inches, but will have a longer loading coil at the base. A VHF-HI antenna covering frequencies above 30MHz and below 450Mhz will be about 36 inches with a shorter loading coil at the base, or it may be a simple 18 inch whip. You'll know you're hooked on scanning when you look at antennas on every vehicle you see, and try to match them up to the frequencies they might be using.
Common Vehicle Antennas (from lowest frequencies to highest).
If you know you are going to listen to only one band, it may be worthwhile to get an antenna for that band, however for most scanning (public safety, business, aviation), the all-purpose antennas should work fine for the Dallas/Fort Worth area. Also, unless you are outside of the MetroPlex, an omni-directional, like a discone, antenna will be your best bet. High gain or directional antennas, like for TV use, will pull in distant frequencies better, but you might miss out on local stuff in the opposite direction. My Radio Shack discone does seem to be more of a UHF and up antenna, so I use it for local stuff and, it seems to pull in UHF air (military) frequencies better. I also use a Radio Shack VHF antenna that works great for VHF, and also does a good job for most other frequencies.
Another important thing to know about is how to connect antennas to your scanner. Higher frequencies like 800MHz and up leak out more than lower frequencies over long cable runs, so make sure you use a high grade coax cable for runs of more than 50 feet. RG-58 is OK for the car and short cable runs, but you'll probably hear a lot more with RG-8, RG-6, or Belden 9913 if you've got a long run.
Finally, get that antenna up there. You'd be surprised what an extra foot of height will do for reception.
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