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The History of Car Antennas

by Eli Laurens

Automotive antennas have evolved since their introduction in the 1930s. Once tacked on as optional equipment, they are now designed into the car as an indispensable accessory. Several different approaches have been used to improve performance while making the antenna attractive, including embedded windshield versions and electric hide-away styles.

The First Antennas

In the 1930s, car antennas were incorporated into the radio body, as most stations were in the AM band, which required a ferrous core receiver antenna. The lack of bandwidth competition and general radio noise in the 1930s also meant that stations could be picked up for a long distance without external receiver antenna hardware.

FM Bands

With the advent of FM bands, the antenna was required to be a straight section of wire bolted onto the body of the car at any convenient location. FM, or frequency modulation, was a different way to broadcast a radio signal. While a clearer signal would propagate further distances, the equipment became more complex. The antenna was still a simple length of hard steel or alloy wire mounted to the body by drilling a hole for the mounting hardware. But the primary antenna had to have a rubber gasket where it contacted metal to prevent it from grounding to the body.

Power and Aesthetics

As luxury car manufacturers sought innovative ways to hide the external radio antenna (seen as an eyesore), they began installing electrical motors that would extend the antenna when needed. A motor pushes a plastic or metal driver through a series of interlocked metal tubes, which would then be used for radio reception once extended. In the 1970s, General Motors got creative with radio antennas, pressing small wires into the windshields of their products to provide radio reception. These wires were placed into a "T" formation, with two wires coming up through the center, then branching out to each side. While these windshield antennas gave decent directional reception, replacing or repairing them was expensive. Most manufacturers standardized antennas in the 1980s so that they were not much more than metal poles for cheap vehicles and electric-powered units for expensive models.

Radio Antenna Technology Improves

Antennas found on most 21st century cars use the same basic principle as the metal pole versions, but they are more compact and stylish. They have a small strand of wire, cut to the same length as a metal pole, but are wrapped into a coil rather than stretched out. This allows for a much shorter unit with the same capabilities. Citizens' Band radios have been using this concept since the 1970s to extend range, but only at the turn of the century has it been applied to general radio reception for cars. These smaller antennas are set at rakish angles to improve the car's appearance, although such placement really does not improve reception.

The Future of Radio Antennas

As new technology comes onto the field, AM and FM radios are soon to be phased out for better methods of communication. While the merits of keeping the media are numerous, satellite broadcasting has become a popular replacement. The satellite radio antennas are even smaller than modern radio antennas and resemble small, black plastic squares. As they are not used to receive terrestrial transmission, they do not need to be long and upright; they only need to be pointed at the satellite and grounded away from the vehicle. As this antenna is much easier to hide, the classic metal pole antennas that became the mainstay of automobiles during the last century will disappear.

About the Author

Eli Laurens is a ninth-grade physics teacher as well as a computer programmer and writer. He studied electrical engineering and architecture at Southern Polytechnic University in Marietta, Ga., and now lives in Colorado.

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