Hello, i would like to make some kind of radar for location people on ground. Best what i can think of is using Ultrasonic Sensor Distance Measuring Module with servos but this have radius about 6 metres. Is there any other option or project with bigger radius? Meybe something with multiple sound sensors? Thanks for any ideas.
ive been thinking about this too and i saw som place a censor ultrasonic censor that coul take up to 10 meters but i think i will add IR Thermometer so that it mostly wil be livving things or hot things it react on and not plants and trees
Check this sensor, it may hit 20 meters, but requires more circuitry.
however im looking for something more powerful and reliably. no matter of cost 
If you google "arduino radar sensor" maybe you can find something useful.
People are notoriously difficult to detect, depending on context.
Maybe FLIR is the answer.
Not Arduino territory though.
Here is a possibility:
http://www.edparadis.com/radar/
I checked, there are still some on eBay, both new and used.
The basic idea is to put the radar working end on a panning-head. The article goes into more detail on enhancements & modifications. It appears to be usable to approximately 30 meters.
Ray