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You can easily get much better signal reception on your USB dongle by replacing the stock antenna with a better antenna, or one better matched to the frequency range you are tuning to. Many of the USB dongles use a PAL or MCX connectors. You can purchase adapters that convert to BNC or SMA adapters for less than $4 on eBay. Once you have an adapter, you can easily connect another antenna. There are many options for antennas.
You can purchase telescopic CB or scanner radio antennas with BNC connectors for under $10 online. These are designed to go on handheld CB radios or small portable radio scanners. They are cheap and they can collapse to fit in your backpack or pocket.
These are simple whip antennas. They're typically magnetically mounted to vehicles, and are usually tuned between 140 MHz to 160 MHz (amateur and public safety frequencies). You can pick up one of these antennas in $40 range, and they'll also work with a mobile radio transceiver if you have one. You will likely need an adapter to convert to the PL-259 plug/SO-239 socket commonly used on these antennas.
Wideband antennas like TV antennas or discone antennas work well. They are designed to work over a wide range of frequencies. Contrast this with most ham radio antennas which are typically tuned to a narrow range of frequencies. Directional TV antennas can be purchased for fairly cheap online (20-40 dollars). TV antennas range from ones that can sit on top of your TV or on a desk to antennas that need to be mounted on your roof. Most US TV antennas use F-type connectors. These are the connectors used on the standard coax cable that goes into your TV. You will need an adapter to connect it to your SDR. Discone antennas are similarly priced. You will probably need a PL-259 plug/SO-239 socket adapter for a discone antenna.
Making your own
Making your own antenna is fairly easy, too. See the projects page for instructions on making some antennas.
You can also check the giant list of frequencies.
|144.390 MHz||NFM||APRS Calling Frequency|
|147.060 MHz||NFM||W4LEE Repeater|
|147.240 MHz||NFM||K4RY 2m Repeater|
|15x.xxx MHz||NFM||Auburn Fire Dispatch|
|155.610 MHz||NFM||Auburn Police Dispatch|
|162.525 MHz||NFM||NOAA Weather Radio Station WWF54|
|444.800 MHz||NFM||K4RY 70cm Repeater|