Radio Principles

Amplitude modulation was the first method used in radio communications and is still an important technology today. Important pioneers were William Preece Guglielmo Marconi, and Reginald A Fessenden, the latter two having short articles about them on this site.

In this section we will look at the general theory of continuous sine waves, relate that to AM, and discuss a few important practical considerations to be borne in mind.

General Theoretical Concerns in AM

All radio communications are made using an electro-magnetic wave that is sinusoidal in nature. Let us consider the general form for the instantaneous value of electrical waves:

The graphical representation is as below:

From this we can see that if we alter anything on the right hand side of the equation, we also alter v on the left.