Home experiments using wireless LAN or mobile phones about electromagnetism? Are there any nice experiments using wireless LAN access points or routers or mobile phones to demonstrate physical features of electromagnetic fields, especially em-waves? 
More precisely I am looking for experiments which use one of the devices above as the main tool and some materials that can be purchased at a reasonable cost from, say, a hardware store or electronic supply store only. I do not impose any restrictions on the cognitive level the experiments aim at; undergraduate level is fine as well as graduate level in em-theory.
Please use separate answers for different experiments.
 A: Simplest thing coming to my mind -- wrapping your mobile (or anything that is able to receive a signal) in some aluminium foil (or in anything made of conductive material).
Then your reciever won't be able to receive the signal. "'Cause conductors block e.m. waves."
A: Mapping EM Waves from Dipole Antennae


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*Apparatus: a wireless adapter with movable antennae, an OS with a wireless signal strength indicator (XP shows the number of bars for instance - or you could write a program for it). 

*Procedure: place apparatus at different locations w.r.t the wireless router and measure the signal intensity as a function of location and the orientation of the receiving antennae relative to the orientation of the emitting antennae (on the router).

*Analysis: From form of intensity function determine signal strenth loss as a function of distance and relative orientation between the two antennae. Repeat in different locations and environments - indoors, outdoors, etc.
A: Show that a metal dish "pantenna" increases Wi-Fi reception:

A: You could construct a Faraday cage and see that if you put a mobile phone inside you don't get any signal.
A: You can construct a slotted waveguide antenna for a wifi router. I guess that you can construct 2 of them, a working one with the slots at the right points, were the microwave power is at its maximum, and one with the slots at the wrong point, with the slots shifted by $\lambda/2$ to be at the point where the microwave power it minimal. The fact that the good one works and the other don't can be seen as a way to check the wavelength of the wifi signal. Maybe the best obtion would be to build one with "sliding slots", in order to go from one situation to the other.
You probably can play similar tricks with other wavelength dependent antenna design.
