What does a TV antenna do?

In Melbourne, antennas are used to pick up a strong signal for your TV,
In Melbourne, antennas are used to pick up a strong signal for your TV,

You may have noticed a metal stick protruding from your roof. The suburban roof is home to many weird objects such as chimneys and possum deterrent devices, but nothing is so ubiquitous as the humble TV antenna in Melbourne. The spindly structures are responsible for catching the signals sent out by the broadcasters, pumping video and audio directly into your living room.

To find out what an antenna does, let’s do a thought experiment. Imagine your antenna was snapped off your roof, perhaps by hooligans or a vicious thunderstorm. You switch your TV on, and a picture may still arrive. However, it will be extremely unclear. Watching a TV show becomes much less enjoyable when you can hardly tell the characters apart. You may notice black and white fuzz appearing on your screen. Now you know that an antenna is necessary for the TV to do its job effectively, but at the moment it is something of a black box as far as you are concerned. It just works, and you have no idea why. Rather than leave you in suspense, let’s discover a little about the basics of how the TV antenna works for analogue television.

Broadcasters send video to you as electromagnetic radiation. Think of this as a wave, where the distance spanning a single peak and trough is on the scale of metres. Different channels use waves of different lengths. For a strong signal, the receiver needs to be a multiple of the length of the wave. The different metal bars across the antenna each correspond to one channel.

Now you know what your television antenna is for, and a little about how it works. While you are not yet an antenna specialist, Melbourne suburbs are great for exploring to spot the different kinds of antennas in use.