The availability of scanners and wideband receivers covering the upper UHF spectrum above 800 Mhz necessitates reasonably priced, wide bandwidth, effective antennas. The most commonly used arrangements for wideband reception on scanners using an outdoor antenna system are multiband trap antennas, a discone, or a simple ground plane antenna. These antennas are usually non- directional. They are generally designed for 50 ohms and are connected to the scanner or receiver through a length of coax cable, most likely RG8 or RG58 type or similar. However, often this arrangement provides disappointing or even poorer results at UHF than the indoor whip antenna mounted on the back of the scanner.
Some compromises have to be made for economic reasons.
There are no single solutions to all of these problems. Perhaps the best compromise is the use of a separate antenna and feedline for frequencies above 400 MHz. Antennas for this frequency range are smaller and enable the use of designs that are impractical at lower frequencies. The discone antenna is quite useful if its dimensions are reduced so its lower cutoff frequeny is around 400-500 MHz or so, yielding an overall size of six inches or less. Actually, the reduction of antenna size is a simple approach but has several advantages.