Radio Principles (Simple)

In this article we’re going to explain all the core mechanisms at play that allow radio to function. This is meant to serve as a quick introduction for people who want to get up to speed.

A more in depth explanation will come later. In the mean time, all sections will link to more detailed explanations elsewhere.

Electricity

Electricity is all about the flow of electrons. Electrons are the constantly moving particles that make up the outside of an atom. Materials in which electrons are able to flow freely, such as metals, are called conductors. Materials in which electrons cannot flow are called insulators.

The flow of these electrons is called “Current”. It is measured in the rate at which the electrons are moving.

The ability to cause electrons to flow is called “Voltage”. It is measured between two physical points, and is in terms of how forcefully a small charge like an electron would move between two points. We can say that voltage is a “scalar” value, which just means it can be represented by a single number. (ex: 10 or -5)

Magnetism

Magnets produce a potential to move, similar in many ways to Voltage. This is called the “magnetic field”. Unlike voltage, however, it is a vector. This means that instead of just being a single number, it now has a direction too. Intuitively, when you put magnets nearby, they are pushed or pulled in some direction, rather than just feeling a certain amount of force.

There is a surprising relationship between the magnets and electrity. In many different ways, one can produce the other.

There are two important outcomes for radio:

1. A changing magnetic field creates an electric field, and a changing electric field creates a magnetic field. This allows us to create moving waves that propogate outwards in some direction. (The Maxwell-Faraday law)

2. A changing magnetic field will create a voltage within any conductors it passes through. This allows us to indirectly measure changing magnetic fields by placing conductors (antennae), where the field will pass through them. (Faradays law)