Diffraction is the phenomenon that occurs when waves pass around corners or edges, such as a diamond cutting a gemstone. You use this effect to transmit your wireless signal by using the destructive interference of another, near by wireless device to continue the transmission. In theory this should have no effect on your wireless signal whatsoever, but with different materials being used for these devices and how you are transmitting it there will be some minor differences in how well it works. Diffraction has what effect on a wireless signal’s propagation? Depending on the material used in your wireless device or cell phone, diffraction may have some effect as to how well your signal propagates.
The reason for this is because different materials interrupt the electromagnetic waves differently and thus change the frequency at which they travel. For example, air molecules do not affect 802.11b/g/n frequencies but concrete walls would significantly impact those frequencies if you were using them in an apartment building. When it comes to the diffraction of light and how that would change how a wireless signal propagates we are limited to what we can test without having a semiconductor lab or other materials that can show how light is affected by material around it.
What effects will diffraction have on a wireless signal :
1. Decrease in wireless signal strength :
Like many things wireless, wireless signals are affected by diffraction. If you were to walk around with a wireless device, you might notice the difference between your signal moving through air and the same signal passing through walls or a small room. Diffraction may also cause there to be more gaps in your wireless signal, which can throw off your position and level of security.
The amount of diffraction that will happen will depend on the material around your device as well as the angle at which it is being transmitted. For example, if you are using certain brands of 802.11b/g/n wireless devices in a concrete room, there are a high likelihood that you will notice a decrease in your signal strength (does not apply to 802.11a). This is because concrete walls do not allow electromagnetic waves to pass through them as easily as air does.
2. Increase in probability of error :
There are also some factors to consider when fighting the effects diffraction can have on your signal and only one of those is the type of material it is using to transmit and receive information. For example, if you were using 802.11b/g/n signals with diffraction and you were using concrete to transmit the signals through, it would have a negative effect on your signal’s strength.
However, this does not mean that you would suffer from a decrease in wireless reliability. What is happening is that your signal strength is decreasing thus leading to a lower chance of error during transmission. This means there will be more instances of ‘the faster you go the slower you are’ problem.
3. Barrier to wireless traffic :
The final and most important factor is where and how the device is being used. If your device is inside an apartment building, and it has been built with concrete walls, then there is a high likelihood that it will have some negative effects on your wireless signal. This goes for both 802.11g/n (does not apply to 802.11b/g) and 802.11b devices because both frequencies of wireless use diffraction.
This can create problems for using wireless devices in large buildings such as schools, hospitals and office buildings where there are many walls around them. Essentially this would create a barrier to wireless traffic that is more likely to fail when traveling through a building rather than the one on the side of the building. While this would be more of an issue in some places than others, it is something you should consider before purchasing your next wireless device or cell phone.
4. Increase use of higher frequencies :
If you have ever noticed that your cell phone and wireless signals have more static in them when driving under a bridge, this can be caused by diffraction. If a signal is traveling through an area where there needs to be a large wall for wireless signals to not be blocked, the frequency being used might need to be changed in order for it to travel through that area.
While this will only become an issue if you are using materials such as concrete or metal siding, it is something that you should note before purchasing your next wireless device or cell phone. The higher the frequency used, the less susceptible it is to diffraction or barriers like concrete or metal siding.
