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.
1930s Mopar Chrysler Delco AM Radio
Later car radio antennas were mounted under the running board. Also, in the 1940's Buick, Ford, and a few other GM brands used an antenna that was mounted on just above the windshield in the center. There was a knob inside that allowed you to turn the antenna down so it was not protruding above the car roof line. The antenna mast could be extended when in the up position and had to be retracted before lowering it. There was a bracket mounted to the center windshield post that would keep the antenna mast from rattling.
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.
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.
The antenna could be either raised or lowered manually with a dash-mounted switch or automatically by turning the radio on or off. The automatic kind will also lower when the ignition switch is turned off. Unlike most car antennas adjusted directly by hand, power antennas retract completely beneath the surface that they are mounted on. This convenience appeared on luxury cars as early as the mid-1950s. The automatic power antenna first appeared in the 1970s.
On many Cadillac models of the 1950s and '60s, the antenna could be raised and lowered by pulling out or pushing in on the radio's volume control knob. The Lincoln Continental of the late 1960s had push-button controls integrated into the factory radio. But most cars had a separate control that often was not even located near the car radio. And sometimes the control on early models was not even labeled (e.g., the late 1960s, early '70s Ford Thunderbird control was integrated into a courtesy light module on the dash panel).
Car manufacturers later sought to make car antennas vandal-proof. They developed the whip antenna- basically, a straight flexible wire or rod. The bottom end of the whip is connected to the radio receiver or transmitter. The antenna is designed to be flexible so that it does not break easily, and the name is derived from the whip-like motion that it exhibits when disturbed.
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.
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.
For satellite reception (e.g., Sirius and GPS), cars like the early 3rd generation Challengers, used roof-mounted antennas that resembled small, black plastic squares. Since they were not used to receive terrestrial transmission, they did not have to be long and upright. They only needed to be pointed at the satellite and grounded away from the vehicle. The AM-FM antenna is integrated into the rear window glass.
In more recent years, more stylish antennas, often called “shark fins” were installed on new vehicles. They are roof-mounted, set at rakish angles to improve the car's appearance, although such placement really does not improve reception