As common as wireless internet connections are, there’s a lot that remains mysterious about them to the non-technical crowd.

Recently My Technology Pros did a WiFi install at a 10,000 square foot home on a private island (living in Florida is really awful; you shouldn’t come here). And even with four access points, there were some parts of the home that simply were impenetrable. The client asked us why this was so. Here, with slight modifications to protect the innocent, was our response:

First of all, we need to discuss in simple terms what wireless internet actually is. All we’re doing is taking the wired internet connection from your cable or DSL modem and instead of plugging it directly into your computer, we’re plugging it into a box called a wireless router. Examples are Apple’s Airport Extreme, Time Capsule or Airport Express. The wireless router converts that signal to radio waves. Wireless devices like your Macbook Pro, iPhone and iPad can send and receive those signals to communicate with the router (and therefore the internet) so that you are not tethered by a cable to a wired router.

So where’s the problem?

In simple terms: radio waves, like all waves, can get blocked or refracted. Several factors affect these waves. We’ll discuss each one below.

First, HVAC equipment — elevators, ovens, stoves, refrigerators — create interference on several levels. These big devices have big electromagnetic fields around them which (obviously) can block, reshape or otherwise interfere with a radio frequency. Since several of those devices (fridge, stove, freezer) are generally found in or near a kitchen, the interference is almost always greatest in that room of the house. Additionally, they are generally thick, have motors or are made of metal; all things that can interfere with waves. You might have noticed that the internet signal drops almost the second you cross the threshold into the kitchen. That’s why! We worked in an office once which was dropping WiFi around Noon every day for a while. We ultimately realized that people were using the microwave at that time, and that killed the signal. (There’s a great video I might be able to dig up that shows on an oscilloscope what happens to WiFi when a microwave is nearby).* Anyway, Channels 1 and 6 tend to avoid microwave interference, so we ended up on one of those channels for the office. That helps with microwave interference, but not with all interference. But I digress.

Secondly, physical barriers like walls present an issue in any building. Just as a wall blocks sound waves, so can it block radio waves like those transmitted from a wireless router. Every wall you put between the transmitter and the receiver reduces the signal. The material used and the solidness of the wall determine how much of the signal is blocked. Foil-backed insulation, metal studs and grates like air returns and vents are the worst; they can create what’s called a Faraday effect. Glass is also bad — especially the thick glass windows you have to protect that house from damaging hurricane winds. This is why almost no signal gets outside of that house; it’s too well built!

Finally, there are low level types of interference like low voltage lighting or lights with dimmer switches, wireless phones, fans or anything with a motor. Each one of these devices in the WiFi signal’s path can effect its strength and reliability.

As for the signal outside of the home, there is also ample evidence to suggest weather conditions play a role. Lightning (obviously) can cause problems, but even fog can block a signal as the droplets of water refract the signal repeatedly. Trees, rain and bad weather in general have been the bane of many satellite customers.

In summary, that house has pretty much ALL of the factors that make WiFi difficult, though we can certainly try some additional tricks if a signal in the kitchen is important to you. Just give us a call.

Hope this explains it!

*I found the video here. It’s probably boring to non-geeks, but it’s fairly short and worth a look if you’re interested in how people are investigating wave interference.