Contents

The basics of radio

Wireless internet uses radio technology. That's right, the same stuff that we've been using since the 1920's to broadcoast audio to our homes and cars. You may be thinking  'ah, it's just radio!', but did you know radio isn't really all that simple? It's actually pretty sophisticated stuff and the explanation of how radio really works touches the crazy subject of quantum physics. Yep. Who could have thought that a simple article on the workings of wireless networks would involve quantum physics?

(To be perfectly honest, I knew, but I didn't want to make you feel stupid)

Animated Maxwell

 

Maxwell's discoveries

So, what is radio exactly? That is a big question and the gentleman bobbing his head above you provided a large part of the answer. He is called James Clerk Maxwell. James was a nineteenth century scientist that investigated the properties of light. James probably wouldn't be bobbing his head here if his investigations had not been so succesful.

In 1864 Maxwell, before the Royal Society of London in 'A Dynamic Theory of the Electro-Magnetic Field', said: "We have strong reason to conclude that light itself - including radiant heat and other radiation, if any - is an electromagnetic disturbance in the form of waves propagated through the electro-magnetic field according to electro-magnetic laws." (clerkmaxwellfoundation.com)

Maxwell discovered that light and a lot of other phenomena that were previously considered unrelated are all electromagnetic waves.

Radio is electromagnetism is light

As you might have guessed, radio is also an electromagnetic wave and therefore also a form of light. There are many more forms of electromagnetic waves surrounding us, such as microwaves, x-rays, visible light, ultraviolet light, infrared light, radioactive gamma radiation and heat. They are all electromagnetic waves of different frequencies (more on frequency later in this article). Below you see an overview of the electromagnetic spectrum. The electromagnetic spectrum is made up of all different frequencies of electromagnetic radiation.

em spectrum

As you can see radio waves are on the very left of the spectum, becuase radio has very long waves, from a few metres long to the size of huge buildings. In contrast to radio waves, gamma rays are tiny.

Energy in electromagnetic waves

The waves with the highest frequency contain the highest level of energy. That is why gamma radiation harms the cells in our body and radio waves don't.

Visibility of electromagnetic waves

Most of the electromagnetic waves are invisible to us, except light, which is often called "visible light" when talking about electromagnetism. As you can see in the spectrum image, visible light has a wavelength (more on wavelength later in this article) the size of small bacteria.

A closer look at waves

Electromagnetism is a natural phenomenon that is difficult to grasp, becuase it is so illusive. We can't see, hear or feel most of the electromagnetic radiation and still it's there in the form of cosmic background radiation, in x-rays, in radio devices, in wireless networks, in the form of infrared light remote controls, etc.

One way to look at electromagnetism is as a wave of energy. When talking about waves, the first thing you may think about is the wave you see when you throw a rock in the water. Electromagnetic waves share characteristics like frequency and wavelength with such mechanical waves. On the next page we will look more closely at mechanical waves and the characteristics they share with the electromagnetic waves of radio.