Alabama's Public Liberal Arts University

Technology Services

Common Sources of Wireless Interference


The University of Montevallo's wireless network transmits on the standard 2.4 ghz radio frequency.  These radio waves are subject to interference from active and passive sources.  Knowing about the sources of such radio interference can help you position your wireless devices to limit or avoid interference.

Active Sources of Wireless Interference

An active source of wireless interference is usually a device that emits a radio signal on the same 2.4 ghz frequency as the wireless network.  Below is a list of common devices that can emit 2.4 ghz radio signals and can thus be potential sources of wireless interference:

Cordless Phones (2.4 ghz) Cordless phones that use the 2.4 ghz frequency can cause severe wireless signal interference
Bluetooth devices Bluetooth devices transmit over a short range 2.4 ghz signal.  Many cell phones, PDAs, cordless mice and other devices use Bluetooth.
Other wireless networks Multiple wireless networks setup within close range can cause mutual interference.
Other wireless devices Many other devices, such as wireless keyboards and mice, use the 2.4 ghz frequency
Fluorescent lights Some newer fluorescent light bulbs emit 2.4 ghz frequency radio waves
Microwave ovens Improperly shielded microwave ovens can emit 2.4 ghz frequency radio waves

If you find that you have a poor or inconsistent wireless signal in your room, see if you have any of these devices nearby.  In most cases, simply moving your wireless receiver father away from the source of interference is enough to solve the problem.

Sometimes, however, it is necessary to remove the interfering device from the environment.  This step can be problematical if the device is immovable or doesn't belong to you.  Under such circumstances, testing your wireless receiver in various locations may be your only option.

Passive Sources of Wireless Interference

A passive source of wireless interference is any substance that restricts or degrades a wireless signal that attempts to pass through it.  Generally, the denser a substance, the greater potential for interference it will have.

The following chart shows materials commonly used in building construction and their potential for wireless interference:

Substance Potential for Wireless Interference
Metal, Concrete Very High
Paper, Heavy Fabric High
Glass, Stone Medium
Wood, Brick Low

As you can see, metal and concrete hold the greatest potential for wireless interference, followed closely by paper and heavy fabric.  Less dense substances, such as wood and brick generally cause very little wireless interference.

Be aware that the potential for interference by these substances is not limited to their use as building materials.  Furniture and other objects made from these substances can cause serious interferences as well, especially if located in close proximity to your wireless receiver.  Avoid placing your wireless receiver on or near a metal desk or cabinet, and keep the area around it clear of stacks of books or clothing.