How do I physically find a wifi device using a laptop or mobile phone

Something that may work:

Go to the hardware store and buy some brass mesh and build a cone. You'll probably need to layer the mesh, then hold your phone in the middle of the cone. The brass mesh should block all radio signals, so if you get a signal, its coming from the direction of the open area of the cone. In theory, you can use this to home in on the device.

FYI, the brass mesh is one component in building a SCIF.

You can always use a Network Monitoring Software Tool like MoocherHunter to triagulate the geolocation of your wifi enabled device.

Actually the mentioned tool is used to triangulate the wifi moochers, but can do the trick for you,given that,the android device is conected to your LAN.

Your router's administrative console can help you find out more about your wireless network activity.It should provide a list of IP addresses, MAC addresses, and device names that it is connected to.with the help of these details this tool will help you locate the device down within 2 meters.(as per developers)

MoocherHunter has been used for law enforcement organizations in Asia to track Wi-Fi moochers.

The software description says it can geo-locate the wireless hacker from the traffic they send across the network, down to 2 meters accuracy. The software doesn't run as an executable in Windows,rather it needs to be burned to a CD, then used to boot the computer. The idea is, with your laptop (and the directional antenna on your wireless card), you'd walk around to triangulate the physical location of the Wi-Fi moocher.

you can find more about MoocherHunter via this link

this way you can locate the device with your laptop

Some wifi routers have a signal strength measurement on them. I know DD-WRT has this. If yours does, then you can do something like this:

• Get a long Ethernet cord
• Plug one end into the router and one into your cable modem/internet connection etc
• Move the router around your apartment and see where you get the strongest signal

Keep in mind, water pipes/metal studs etc can all distort wifi signals

Another option would be to make your own directional antenna, kind of like this.

You could also check out this page for some useful command line linux wifi commands.