Improve the Quality of FM Reception

The single most important component affecting FM reception quality is the antenna.  This device, which is simple in concept yet complex in operation, intercepts incoming electromagnetic radiation that has been transmitted by the radio station.  As the radiation comes into contact with the antenna, minute amounts of electrical current are induced into the antenna and the coaxial cable that links the antenna to the tuner.  The tuner then amplifies these current variations and extracts the usable sound information.

Multipath Distortion
Signal reflections that arrive at a receiver out-of-phase, slightly delayed in time, with the primary signal.  This tends to blur or distort the principal signal.   The effect on FM can range from a barely audible fuzziness to severely distorted sound quality, particularly at the high frequencies or treble.   The degree of distortion will depend on the number and relative strength of the signal reflections.

RF Overload
Common signs of radio frequency (RF) overload include any or all of the following: stations which show up at many points on the dial in addition to their assigned frequency, stations that “blanket” other adjacent stations, audio distortion on voice and music peaks and excessive noise despite a strong signal level.   The specific effects of RF overload will vary depending on the tuner, its characteristics, and the strength of the signal supplied to the tuner.

Coax cable is strongly recommended as lead-in for any antenna installation.  Although initially more expensive and exhibiting slightly greater signal loss than twin-lead, it will far outlast any twin-lead, it will insure unsullied delivery of the antenna’s signal to the tuner and its signal losses will remain fairly constant throughout its life.   Regardless of which lead-in you select, though, remember to keep it as short as possible.   The longer the lead-in the greater the signal loss will be.

It should be pointed out that FM antennae are available in both 75-ohm and 300-ohm versions for use with both types of leads.  Tuners and receivers are in many cases supplied with both impedance inputs and in cases where only a 300-ohm input is supplied, an inexpensive, readily available balun or matching transformer can be used.   If one needs to be installed at the antenna itself, because it is a 300-ohm antenna and you are using 75-ohm lead-in, make certain that you use an outdoor-type, waterproof balun.

Booster Amplifiers
Booster amps are useful only in fringe areas, when the antenna lead-in is excessively long causing substantial signal loss, or when multiple or a large number of sets are to be fed from a single antenna.  Booster amps are always best placed at the antenna itself.   The rule is to put the amplifier as early in the chain as feasible, thereby, compensating for any loss in the signal before it occurs.