Motion detection behind wall

Please help me out with this....I need to make a multipurpose robot for my college project for which I need a sensor that could detect human motion behind doors/walls .I suppose a doppler radar that transmits a wave of 10ghz frequency would do this as microwave can penetrate walls.But got a mixed opinion about this on internet references..I just need to build a prototype and so false positives can be tolerated to an extend.So someone please do help me on this as soon as possible.....

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sounds like a military project to me.

Yea we plan to build a prototype of a robot for defence application.So if i cant use doppler radar What else can be a suitable alternative?? and why cant a 10Ghz doppler radar do the same inspite of its wall penetration property ???

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http://www.ebay.com/itm/Wireless-Module-Microwave-Doppler-Radar-Motion-Sensor-/130512020245

Sounds like a typical college project to me.

(removed your other thread)

For this specific application, using microwave with a moving robot introduces some serious complications. My recommendation would be to disable the microwave while the robot is moving, then stop the robot, and scan using the microwave sensor for motion behind walls (but ensure the robot is stationary).

The RCWL-0516 microwave radar sensor is a great start to handling this. I wrote a blog post on the RCWL-0516 and Arduino, if you're interested in testing the method I used above, check out the post:

(RCWL-0516 Microwave Radar Sensor)