The theory behind radio technology is actually
disarmingly simple.
To better demonstrate this point, here is a little experiment that practically
anyone can do; first, take a fresh 9-volt battery and a small coin. Then, tune
an AM radio to static (i.e. where there are no pre-existing signals coming
through). If you place the battery relatively close to the antenna and tap the
coin against the battery terminals, you will hear this signal relayed over the
radio (it will break the static, effectively broadcasting the signal). You
couldn't use this method for much more than Morse code (and probably only over
a distance of a couple of centimeters), but still, it is a pretty impressive little
experiment, is it not?
At its core, radio isn’t much more complex than that. But
how does it actually work?
Well, basically, it all has to do with these things
called ‘sine waves’.
A sine wave is a radio wave that has been encoded in a specific way (this
prevents it from getting confused with any other radio wave). Each sine wave
operates along a different frequency, so there is no interaction between
signals. Without sine waves (or any similar technology), it would be next-to
impossible for us to use cell phones, AM/FM radios, walkie-talkies, TV, GPS and
much more, because all the signals would interact with one another, all at the
same time.
A radio, of any kind, needs a receiver. In the case of
our battery experiment, for example, there is both a transmitter and a
receiver. The battery/coin setup is the transmitter and the AM radio is the
receiver. Radio devices that can both send and receive signals are called
‘transceivers’.
Again, this setup is actually quite simple. The
transmitter encodes information (such as a TV broadcast, or a person’s voice)
into a sine wave and then transmits it, via the electrons in its antenna. The
receiver then captures the signal in the intended antenna (it has electrons
that are coded to the same frequency as the transmitter) and then decodes it,
using the radio’s internal system, so that the original information is readily
available to the user.
The science behind the decoding process is a little more
complex, but it isn’t really too difficult to grasp. We’ve run quite a few
answers on the ‘ins and outs’ of that stuff lately, so check those out if you
wish to know more. Thanks for your question.
