The airwaves are replete with songs about being born wild, finally getting back on the road again, or traveling in fast cars down one highway or another. A car’s antenna captures signals zipping effortlessly through the air so you can listen to those tunes on the radio. Yet, people have gone to great lengths to customize them with all manner of accoutrements that range from tennis balls, to styrofoam smiley faces, flags, and other crazy toppers.
Since the 1930s, car antennas have gone through several evolutionary phases. The standard length of an antenna used to be around 31 inches, but as technology has advanced, antennas have become shorter and smaller. Today, you’re far more likely to find a low-profile shark fin than a straight arrow protruding into the air. Not only do these fin-styled antennas provide a sleeker, more aerodynamic look, but they can also hold several antennas, each capable of snatching different signals (GPS, Wi-Fi, 4G/5G, etc.) from the air, making it a truly multi-functional piece of equipment.
Then you have antennas that appear to have a coil wrapped around them — also referred to as fluted or spiraled antennas – first introduced in the 1950s. There are actually a few reasons for the design, but let’s start with what seems to be a prevailing misconception — its only function is to keep the antenna from vibrating, thereby reducing the noise it creates as it slices through the air at breakneck speeds. While that’s certainly one helpful element, it’s far from its only purpose.
Spirals make the music shine
That coil is also known as helical or Scruton strakes, which can also be seen on ventilation and factory smokestacks, and they keep them from shaking apart in the wind. However, explaining the exact how and why these coils do what they do would involve diving into computational fluid dynamics and concepts like aeroelastic flutter-induced oscillations, vortex shedding, and harmonic frequency — none of which we’re going to do here. Just know that consistent vibration, especially at specific frequencies, can disrupt signal reception, and there’s a trunk full of solid math and science to back it all up.
Those coils serve other functions that are just as important to an antenna’s overall effectiveness, making them better than those without coils. First, it allows antennas to be shorter while still boosting signal reception, because it can receive electromagnetic waves over a wider range, making it ideal for monitoring multiple frequencies simultaneously. What’s more, thanks to their circular polarization, these broad-range antennas can both receive and transmit electromagnetic signals while also receiving linearly polarized waves in any orientation.
For the longest time, the size of the antenna did matter — in this case, the longer it was and the higher it sat on the car, the better the reception. Look at any older model car still driving around today, and you might see that nearly three-foot antenna, complete with a tennis ball. Or you might not, because those old-school antennas are fragile and tend to break off easily. The newer, coiled versions are smaller and sturdier, making them far more capable of withstanding even the nastiest wind or rogue car wash.
