What is a Radio

The simplest answer may be that a radio is a device that either makes, or responds to, radio waves. You may have already learned that radio waves are part of the larger group of the electromagnetic waves, the group which also includes light, x-rays, even gamma rays. These waves can travel through materials, like air or wood or glass or concrete, or even through the empty vacuum of space. In fact, they travel best though empty space. Some of the waves, such as light, x-rays, and gamma rays can pass reasonably well through varying amount of water or metal. The radio waves we are interested in don’t penetrate water very well at all, and only a small amount of metal will stop them.

 

If all a radio did was just to make or respond to radio waves it would be a very fascinating scientific curiosity, but maybe only little more than that. It is the ability of radio to permit communications that makes it so vital to out modern society. Try to make a list of as many different ways you can think of for one person to communicate with another person. How many of those ways require the two people to be close to one another? For which kinds of communication may the persons be far apart? Which one happen right away, and which may take hours or even days or weeks? Which ones have to have a wire connecting the places where the people are? Which can take place without wires?

 

A radio transmitter (some just called a transmitter) is a device that can take some kind of information (might be voice, or music, or computer data) and convert it into the right kind of radio waves that can pass through the air or through space, without any wires. The waves are launched into space by an antenna. At another place a radio receiver (often just called a receiver) intercepts the radio waves from the air or space (using its own antenna) and changes the radio waves back into the information that the people need. The receiver doesn’t “use up” the radio waves, in fact, many, many receivers can “listen” to the radio waves produced by a single transmitter.

 

For two-way communications to take place (two-way radio) there must be a transmitter and a receiver at each location. Sometimes the transmitter and receiver are combined into a single box, which can then be called a transceiver. A modern cellular telephone is an example of a transceiver.