Understanding WiFi interference and impedance


Learn more about WiFi interference and wireless signal interference. Interference can be caused by other devices on your own network or neighboring WiFi networks.

Understanding Interference

Interference can be caused by a large variety of devices, mostly from other devices on your own network or neighbouring WiFi networks, but can also include:

  • Bluetooth headphones or speakers
  • Microwave ovens
  • Cordless phones
  • Garage door openers
  • Any other devices that may be broadcasting wirelessly

Unlike wired connections, which are dedicated, wireless devices have to share the wireless connection with all other devices. Even if your subscribed plan might be 120Mb/s, if your WiFi router tops out at 60Mb/s, you won’t get full speeds wirelessly. If you have three wireless devices simultaneously trying to use that same 60Mb/s capable router, the speeds you get on one device could be only 20Mb/s or less. So your single device is getting interference from co-workers on the same network. Modem WiFi Range Diagram

Similarly, if there’s 5, 10, 20 or more networks around you, all with many wireless devices connecting, the speeds could be greatly reduced from all this usage. As such, you might suffer slow speeds during congestion. The best options are to reduce competition on the network by using a hardwired Ethernet connection whenever possible. If your router can use 5GHz (sometimes called 5G) wireless, try to use devices only on 5GHz when possible. The 5GHz band can handle a lot more devices and runs faster too. It’s not as compatible with old devices and has a more limited range, so reserving 2.4GHz use for only older devices or equipment far from the network can help.

Understanding Impedance

Impedance is anything that reduces the power of the WiFi signal. Think of trying to talk to someone through a wall compared to face-to-face in the same room. Without the wall impeding your voice, you can talk more quickly, clearly, and it’s easier to be understood.

WiFi is basically light, just at a much lower frequency. You might even say that WiFi is a colour of light that we can’t see. The WiFi modem puts out a bright signal, and different things in your environment will ‘dim’ the signal, making it hard for your devices to ‘see’ the WiFi. A good analogy would be how you can see a flashlight shine through a piece of paper, or through your hand, but if you try to shine it through a wall, you’re likely not going to see anything.

Here is a list of common things found in an office that can impede the WiFi signal:



MaterialImpedance level
AirVery Low
Thin Glasslow-medium
Thick or double/triple pan glassMedium-high
MetalVery high
MirrorVery high

Newer WiFi equipment has made great strides in being able to overcome some of these obstacles a little better, but there’s still no getting through thick concrete walls. This makes placement of the WiFi modem or access point critical to ensure impedance is minimized. Our technicians assess the business at install, and will try to position the modem to maximize coverage within the space. If you are having issues getting WiFi in a particular place in the business, try moving the modem to reduce the number of things that may be in the way that could impede the signal.

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