Homemade AM/FM Radio Antennas
An AM antenna is one thing and an FM antenna is another. They are at opposite ends of the radio spectrum. The AM radio wave is a long wave. The FM radio wave is a short wave. What one needs for an AM/FM antenna is two opposites functioning in the same antenna. Car radios feature AM/FM and satellite reception combined in single antenna by a means of matching coils. Homemade antennas are less expensive. They can be designed for indoors, outdoors or other conditions affecting reception.
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The Antenna Section
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A combination AM/FM antenna is compromised for size. It must fit the space, whether in your car or your living room. For this article the antenna of choice is an 18-inch telescoping antenna (see example and instructions in References). This antenna is supported by a broadband booster or amplifier that makes it an active antenna system. Other AM/FM commercial antenna systems costing $20 to $80 feature tower (vertical) antennas with a built-in adjustable amplifier. Others feature outdoor omnidirectional antennas and a noise-reducing Gamma-Loop technology with a high-gain signal amplifier on FM. This antenna also features "patented conduction circuitry" that isolates the AM and FM antenna elements for improved reception.
The AM/FM/SW Active Antenna
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The circuit shows an active antenna that can be used for AM, FM and shortwave (SW). It is similar to a 20- to 30-foot wire antenna on the shortwave band. The circuit is made for receivers that use untuned wire antennas. It is powered by a single 9-volt battery and contains about a half dozen parts. The unit can be built into the base of the telescoping antenna.
The proof of the antenna system is in its performance. First, see how it improves reception over the three bands. Next, try one or more of the commercial models from Universal Radio, Inc. Ask the manufacturer if you can test their antenna system. Another possibility is to take your homemade system to their showroom and do a side-by-side comparison. The results might surprise you.
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