When working with AM/FM radio equipment, you may find that a lot of components, such as the antennas, are made of aluminum. It may strike one as odd, but aluminum is used more often—and more effectively—than many “stronger” metals.
There are two main reasons why the lightweight metal is used for things such as antennas and receivers, and they balance each other out. Aluminum is the metal of choice because it balances conductivity and cost.
Conductivity: Where Aluminum Ranks Among Other Metals
Aluminum is often used with antennas and broadcasting equipment because it is a good and reliable conductor of electricity. In fact, few metals in electrical equipment are better conductors of electricity than aluminum. Because of this, airwave signals (which are electrical impulses) are better collected from open-air electrical conductors.
There are a few better metals to accomplish the task than aluminum, and they include gold, silver, and copper. In fact, silver and copper are at the top, with copper only slightly less conducive to the task than silver. In this, aluminum ranks around fifth in the conductivity contest. So why aluminum over the others?
Cost: Aluminum Provides Value While Allowing For a Quality Signal
Most broadcasting technology uses aluminum (and far less frequently, copper) for one simple reason: cost. In 2015, copper costs as much as four times as much as aluminum, and silver costs almost twenty times as much. While copper is often used in wiring, the wiring is protected and is therefore less susceptible to the elements. By comparison, aluminum is much more commonly used in exposed material because it is easily replaceable. Both copper and aluminum, if exposed to the elements, will develop a patina, and will still function effectively. However, most developers of broadcasting equipment find that aluminum’s conductivity, for the cost, is more than sufficient.
Can one go cheaper than aluminum in developing a receiver? Yes. Cheaper AM/FM equipment might use antennas made of iron (which costs about one-third to one-fourth as much as aluminum) but the quality of reception is heavily compromised. The signal strength of iron to aluminum is barely comparable. Because of this, most manufacturers are willing to sacrifice at least some signal strength to reduce the cost, but not as much as lower-class metals other than aluminum provide. Because of this, high-end production will usually use copper, but for basic use, aluminum remains the metal of choice among broadcasters.