Radio, a simplified explanation.

Most of us really don't understand radio. It is sort of like a car. We insert key and drive away. We have some idea about how a car works, but it is only a sort of generalized idea. Most folks understand radio even less, even though we use every day.

So here is a bit about what Radio is. It is pretty simplistic, but it may help you understand many of the more complex concepts.

If you take a coil of wire, and arrange it near a magnet that is spinning like a wheel, so that first one end passes the coil, then the other end, you will generate a small current in the wire.

If you were to hook a meter to the coil you would notice the current get larger, then smaller, then reverse direction and get more negative and then less negative (called polarity, first positive, then negative) as the north then south end of the magnet pass the coil.

If you spin it fast enough, perhaps so that the alternations occur 60 time a second you will have something like what is in the walls of your house. 60 cycle alternating current. You can find where the wires run in your walls by using a modern stud finder which usually also has an AC (alternating current) detector. This is so you don't pound nails through the wire. Not good. But you can only detect the wire for a very short distance. The alternating current in the wire creates an electromagnetic field around the wire, but it does not extend very far from the wire.

If your spin the magnet reallllllllly fast, say 500,000 time a second, you would be able to detect the electromagnetic field much farther away. However spinning something that fast is a mechanical impossibility. 

Fortunately some smart person noticed that if you put an non alternating electrical current (called direct current or DC, like from a battery) through a piece of quartz it will actually vibrate at some constant frequency. This vibration will change the direct current to one with the constant frequency superimposed on the DC.

By changing the shape and size of the quartz crystal, any desired frequency can be generated, Now we can easily generate frequencies of many million cycles per second. Using some other electronic components we can amplify the power of the electromagnetic field and with the proper receiving equipment, we can detect the field at great distances.

So what. Well, if you can detect the magnetic field, you can tell when it is there, and when it is not there. Suddenly we have a way to transfer a message. Turn the field on and off in some pattern at the transmitting site. At the receiving site, listen to the pattern and translate the code into text.

 A Mr. Morse created one of many encoding schemes. His is now the most common, called of course, Morse Code. The basis for this is a Continuous electromagnetic Wave (abbreviated CW) that is interrupted in some clever coding scheme.

Now we can really get something done with this electromagnetic wave thing. But using this CW method required much training and diligent application. Wouldn't it be better to just TALK? Well that came next. But it took many years to make it practical.