Make Wi-Fi Visible #1 – Radio Frequency Propagation

October 10, 2014

As we all know, Wi-Fi is amazing. The only thing is… it’s invisible.

So let’s start by explaining what makes Wi-Fi invisible? Wi-Fi uses radio frequencies electromagnetic waves to transfer information. These waves have wavelengths that are not within the visible space.

Light is also an electromagnetic wave. However, its wavelength is within the visible spectrum (between 330 nm and 700 nm). This is what make the light visible to the human eye. In fact, any electromagntic radiation having a wavelength between 330 nm and 700 nm is called “light” or to be precise “visible light”.

This means that we can explain Wi-Fi concepts using light analogies. In this set of articles, that is what we are going to do using simple drawings.

EPISODE #1 - RADIO FREQUENCY PROPAGATION

Today we are going to start with the simple concept of radio frequency propagation. This is the idea that a radio frequency electromagnetic wave is losing energy as it travels away from its source. We usually represent is this way :

This concept is illustrated below using the analogy of a light bulb. As you can see, the light is the most intense where the light bulb is (the source) and is getting less and less bright as you move away from the bulb.

If we compare this example to Wi-Fi, the bulb could be an Access Point using an omnidirectional antenna. The signal strength would be the highest near the AP and it would decrease as you go away from the AP.
Does it make more sense?

“Episode #2 – Radio Frequency Reflection” coming next!