Radio Transmitter Fundamentals
How does a radio transmitter work?
This depends in part on what you mean by transmitter. Transmitter can refer
to an entire radio set responsible for transmitting a signal, or just the
particular bits of such a set that amplify the signal up to a high enough
level to be detectable once radiated.
The first thing a transmitter needs is a carrier signal. this is the radio
frequency it will transmit at. (Radio frequency, or RF, is an electrical
variation in the thousands, millions, or even billions of times per second)
The next thing it needs is intelligence. (something we're actually trying to
transmit, such as music or a voice) This is modulated onto the carrier
frequency in one of two ways. Frequency Modulation (FM) is where the
intelligence varies the frequency of the carrier signal. And Amplitude
Modulation, (AM) where the transmitted strength is varied instead.
After these two signals are provided, a transmitter just has to amplify
them. The exact amount varies, from a few watts for a cell phone, to
millions of watts for high powered RADARs. The methods of amplifying
usually include either transistors, (simple electronic components that
increase power by acting like a gate on a larger power source), or Vacuum
tubes (think "really fancy light bulbs") that accomplish the same thing as a
Click here to return to the Engineering Archives
Update: June 2012