Radio Scanner Guide
Part 7: Radio Scanner Accessories and Antennas
1. Flexible "Rubber" Handheld Antennas - Most handheld scanners come with a flexible "rubber" antenna, popularly referred to as a "rubber duckie". They consist of a coil of wire wrapped in a rubberized-plastic exterior. These antennas are small and convenient, but do not typically perform as well as a telescoping whip antenna. However, there is a significant difference in performance between different models of rubber antennas. If you are constantly moving and prefer a rubber antenna, you may still enjoy significant improvement in weak-signal reception with your radio scanner by purchasing a different rubber antenna. You may want to read some independent testing results verifying such improvement prior to purchasing a new antenna.
2. Telescoping Whip Antennas - - Telescoping whips antennas are extendable metal antennas made from a series of short tubes. They generally give better performance than a rubber antenna and are recommended for portable use where the small size and flexibility of a rubber antenna are not needed.
3. Mobile (Car-mounted) Antennas - When listening to your radio scanner in a vehicle, the vehicle's metal body will act as a shield, blocking most radio signals. A mobile scanner antenna is recommended. There are two types - magnetic-mount and glass-mount antennas. Magnetic mount antennas couple with your car's metallic body, using your car as a ground plane in order to improve reception. Glass mount antennas may use adhesive or a suction cup to adhere to a window or sun roof. They typically do not work quite as well as magnetic-mount antennas, but still provide the advantage of being outside of your vehicle's metal body and should out-perform any antenna inside of the vehicle. Glass-mount antennas can be less conspicuous and also avoid scratching your car's paint. Be advised that some state and local laws prohibit using scanners in vehicles.
Magnetic-mount antennas may also be used as a quick indoor base station antenna for with improved reception over a flexible or telescoping whip antenna. The magnetic-mount antenna should be mounted on a metal sheet or screen. Metal screen, small-mesh metal fencing, and cookie sheets, and aluminum foil are popular choices.
4. Base/Outdoor Antennas - These antennas are designed to mount on your roof, chimney, or a mast. Antenna reception range is directly related to height so scanner antennas should normally be located as high as possible. The three main types of antennas are dipoles, ground planes, and discones.
Dipoles and groundplanes have a fairly narrow bandwidth - that is the range of frequencies over which they will work. They have a small amount of gain and are small and inexpensive. A discone antenna has no gain but has a very wide bandwidth. Most discones sold for use with radio scanners are advertised as having a range of 25 to 1300 MHz, the entire scanner spectrum. In practice, these antennas usually do well for frequencies greater than 100 MHz but not as well on the VHF low band (25-54 MHz). Outdoor scanner antennas
5. Coaxial Cable to Antenna - Your antenna will require coaxial cable (commonly called "coax") to connect it with your radio scanner. The most important concern when choosing a cable is signal loss. With a high-loss cable, signals from an outdoor antenna are often weaker than from the antenna on top of your scanner. Obviously, this scenario would negate the purpose of erecting an outdoor antenna!
Cable loss is dependent upon cable type, cable length, and frequency. Loss increases as the length of cable increases and frequency increases. If a certain length of cable attenuates the signal by 50%, doubling the cable length will increase attenuation to 75%. The utra-high-frequency 450-470 and 800/900 MHz scanner radio bands are very sensitive to signal loss. Cable types available with acceptable loss include "RG-8", "RG-213", Belden "9913", Belden 8214, "RG-6", and "G-59". Avoid RG-174 completely. Avoid RG-58 for runs over 10 ft due to its high loss.
RG-6 (preferred) and RG-59 (acceptable) are designed for television systems but work very well for radio scanners. These two cable types are usually much cheaper and smaller than the RG-8, RG-213, and Belden 9913 cables, yet perform almost as well and much better than RG-58. The main difference is that they have an impedance of around 75 ohms, designed to match television antennas and receivers, while the other cables have an impedance of 50 ohms, like most scanner and 2-way radio equipment. However, any signal loss from this impedance mismatch is negligable. RG-6 and RG-59 will still have far lower overall signal loss than either RG-58 or RG-174 at scanner frequencies.
Another cable type known as "hardline" (due to its rigid shape) has even lower loss than the above recommendations. It is expensive and difficult to route, due to its rigid shape. It is really only needed for special applications, like long cable runs (e.g. over 50 ft.) at extremely high frequencies. Several scanner vendors sell it, but is beyond the needs of most scanner listeners.
Most listeners will prefer to buy cables with connectors already attached. Often adapters will be needed either at the antenna end or the scanner end. If possible, buy cable with the correct connectors to minimize adaptor use, as each additional connection adds some signal loss. Those handy with a solder iron may buy exactly the cable length they need (leaving extra for a drip loop) and install their own connectors.
The following table provides links directly to item listings on each vendor's site.