WiFi Signal Level Fluctuating

[halfpower]

I have a wifi adapter with an external antenna for a wireless network. I built a makeshift parabolic reflector from an empty can of fruit cocktail. I examined my received signal strength and noted that it was fluctuating between 5.0*10^-8 mW and 8.0*10^-8 mW. The reflector was then removed to how much the signal strength would change. It decreased to 2.0*10^-8 mW. After a few minutes it decreased further to 1.3*10^-8 mW. It appears that each configuration produced equal amounts of fluctuation. Preliminary tests also showed that fluctuations were occurring more rapidly when the reflector was in place. This rapid fluctuation, however, is rather difficult to explain. Reflector or not, does anyone know why these fluctuations occur?

 

[halfpower]

By the way, I used the Asus WiFi@Home wifi-g wireless PCI adapter to perform the experiment. I obtained the data using the packaged software.

**Regarding reflector, I think the word cylindrical is probably more appropriate than parabolic.

 

[Mday]

the change isnt that much, i am assuming you're using mW, and not dBW. you're well within normal fluctuations, imo. It's hard to describe what's normal, but I will say that it's not abnormal behavior.

multipath propogation will lead to some fluctuations. External antennae with long cables (relative to effective antenna height) will also lead to this type of problem if the cable is not properly shielded.

Besides, I wouldn't trust the software anyway.

 

[halfpower]

It might be normal, but a 60% change sounds like an awful lot.

 

[brentkiosk]

A 60% change in power is a little over 2 dB. That sounds within normal behavior.

 

[beer]

There is a reason that RF power is usually given in dBm. As mday said, it is primarily a multipath thing, any small change in phase or signal reflection will really kill it, under certain circumstances.