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Make Wi-Fi Visible - Season 1 Recap

12/31/2014

As 2014 is ending today, this makes it the perfect day to do a recap of the first season of Make Wi-Fi Visible. This series of articles is aimed to explain Wi-Fi concepts using the light analogy.

The first season focused on the major Radio Frequency (a.k.a. RF) properties. Since both Wi-Fi and light are made of electromagnetic waves, the idea was to use light to have a visual idea of what these RF properties are and how they can affect our Wi-Fi networks.

Here is a recap of each episode. Feel free to click on the links provided to read the full episodes. Comments and feedbacks are always welcomed :)!

Episode #1 - Propagation

Propagation is the idea that a radio frequency electromagnetic wave is losing energy as it travels away from its source.

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Episode #2 - Reflection

Radio frequency reflection occurs when the electromagnetic wave encounters a flat surface and is reflected with a loss of energy.

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Episode #3 - Refraction

Refraction occurs when a radio wave is moving to a medium having a different density.

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Episode #4 - Diffraction

Radio waves tend to bend around sharp objects creating a new wave front. This phenomena is called diffraction. This allows the waves to go around an object and still reach a receiver.

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Episode #5 - Scattering

Scattering happens when the diffusion of the signal is reflected in multiples directions when hitting an uneven surface.

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Episode #6 - Absorption

Absorption is the fact that a radio wave loses some of its energy going through a medium or an obstacle.

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As of today, I am happy to announce that season #2 of Make Wi-Fi Visible will be released in 2015! This second series of articles will focus on antennas.

Happy new year 2015!
Bonne année à tous!

Written by François Vergès

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Make Wi-Fi Visible #6 - Radio Frequency Absorption

12/27/2014

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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 #6 - Radio Frequency Absorption

Let’s finish this first series of article with absorption! Absorption is the fact that a radio wave loses some of its energy going through a medium or an obstacle. A radio wave will typically lose some of its energy as it travels trough the air du to absorption.

Light waves are easily absorbed. Indeed, the simple fact of blocking a flashlight with your hand will block the light. A wall will also totally block light. Some other materials like glass will let the light pass through with less absorption.

As you probably understood, absorption depend on the material the radio wave goes through. Typically, a Wi-Fi wave will be less absorbed going through a dry wall than going through a brick wall. While deploying Wi-Fi, it is important to keep in mind what objects absorbe Wi-Fi radio wave the most in order to find the best APs locations. Performing on-site site survey will help you determining the absorption of the objects of your environment.

Written by François Vergès

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Make Wi-Fi Visible #5 - Radio Frequency Scattering

12/12/2014

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Episode #5 - Radio Frequency Scattering

Radio waves are sometimes scattered. It happens when the diffusion of the signal is reflected in multiples directions when hitting an uneven surface. It could be the sunlight going through a cloud or a radio wave hitting a rain drop.
Scattering is illustrated below:

If we think of sunlight going through multiple clouds, some clouds will be thicker and some others will be thinner. The light will be scattered since it will be reflected unevenly as illustrated below:

As a Wi-Fi professional, it important to remember that as the scattering of a signal continues to occur, the signal will lose its integrity and eventually die off. Scattering could happen indoor if you have a lot of inside trees. It could also happen on outdoor Wi-Fi bridges while raining as the signal hits rain drops.

Written by François Vergès

"Episode #1 - Radio Frequency Propagation" is still available!
"Episode #2 - Radio Frequency Reflection" is still available!
"Episode #3 - Radio Frequency Refraction" is still available!
"Episode #4 - Radio Frequency Diffraction" is still available!
"Episode #6 - Radio Frequency Absorption" coming next!