How to Increase the Range of a Radio Scannerby Fred Decker
There's an unseen world of radio communications going on in your area, 24 hours a day. From construction crews to passing truckers and emergency services to aircraft, radio signals are used for a wide range of purposes. Using a scanner to monitor radio frequencies can be a fascinating hobby, or a convenient way to keep track of your own company's operations. Unfortunately, a scanner's reception is sometimes limited by the supplied antenna and other factors.
Sometimes, just changing the location of your scanner can make a difference. Position your scanner in the upper floor of your house whenever possible, or near a large window. Some walls in your home, usually the central walls, have more electrical wiring in them than others. Those will limit your reception, so keep the scanner away from them if you can. Many appliances, such as microwaves and refrigerators, generate a great deal of electrical "noise" while operating. Keep your scanner physically separate from them, and use an electrical outlet that doesn't share its circuit with a problem device.
If you're using a handheld scanner, you're limited by the reception of the flexible "rubber duck" antenna that comes with most models. Reception in many bands can be improved by purchasing a telescoping metal antenna, which can be fully extended when in use and then collapsed when unneeded. Its reception of specific bands will vary depending how far it's extended, so do some experimentation. Upgraded flexible antennas are also available, with longer coils built in to improve reception. If you use your mobile scanner in a car, consider mounting a permanent antenna on the vehicle. If that's not possible, you can use a temporary window mount.
Base-model scanners usually include a small telescoping antenna that screws to the top of the unit. Longer telescoping antennas can be added to most base models. Some use a cylindrical PL-259 connector and others a push-and-twist BNC connector. Retailers such as Radio Shack carry adapters if you need one. For the best reception, consider mounting an outdoor antenna to a mast or rooftop mount. Some are designed to receive a single band of frequencies exceptionally well -- ideal for business use -- but most are compromise designs intended to provide acceptable all-around performance.
Choosing Outdoor Antennas
Outdoor antennas come in several varieties. If you listen primarily to a single group of frequencies, a simple dipole antenna -- a vertical "whip' -- will receive that band very well while screening out others. So do Yagi-type antennas, which arrange multiple elements in a flat array. Yagi antennas are directional, and must be pointed toward the source of your signals. For good reception across multiple bands, a discone-type antenna, consisting of prongs pointing in multiple directions, works well. So does a log dipole array, built rather like a traditional TV antenna. Be sure your antenna receives the same frequencies as your scanner, or you'll miss signals.
Mount an outdoor antenna on a high area of your roof, away from power lines and potential obstructions. Use a length of mast with a tripod mount or wall brackets, or mount the antenna to a free-standing mast or tower. Higher is better, and ideally your antenna will be above any obstructions such as trees. Use high-quality 50-ohm RG-8 or RG-58 cable to connect the antenna with your scanner. Observe all appropriate safety measures during installation. Use a scaffold or a sturdy ladder, don't mount your antenna in poor weather conditions, and have a friend's help. A safety harness is best, if you can borrow or rent one.
A few other accessories can be helpful. If you're using a directional antenna, install it on a remote-controlled rotator so you can turn it to improve reception without getting up on your roof. If you're in an outlying area, a preamplifier might improve your signal. A frequency converter installed between your antenna and scanner can add bands your scanner won't hear, converting them to a set of VHF frequencies. If you have trouble hearing weak signals because of a noisy listening environment, noise-cancelling headphones can also be useful.
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