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Hi, I work as a teacher at an army technical school.
I need a schematic on a simple FMCW-radar (VHF or UHF) that my students can build during a week(4-5 army cadettes, totally 30 lessons). It should use an oscilloscope as a display (A-indicator ?) it should be able to indicate a moving car.

I am really prepared to take any simple radarschematic, it don't has to necessarily be a FMCW-radar. Anything goes..

Kindest regards,


Hi There,

I take it that you want to measure distance to target not speed?

Do you have available a doppler radar head with a Varactor tuning diode (Type used in alarm sensors,etc)? This must be able to smoothly change the frequency of the unit over at least 300MHz range by varying the voltage on the varactor.

If you do, than i can email you a simple diagram on the requirements. There are a few things you will have to be careful of when using simple systems, the main one will be to avoid radar clutter(to many targets) when doing your testing, ideally some DSP would be required to filter the resultant signal.




Hi Graham I don't have a doppler radar head with a Varactor tuning diode, but please email what you have to me.

P.S. Do you know any other forum on the nrt where I can put out my request ? Perhaps a ham-forum ?


Anyone know about the FMCW radar signal processing point of view?



"doppler head" is a fancy name for one of the transmit/receiver/horn modules that you commonly see in supermarkets opening the automatic doors.  Some burglar alarms use them too.  M/A-com made a boat load of them, and they are pretty common at flea markets or on Ebay.  They transmit out around 10 GHz, I think, using a Gunn diode oscillator, and the same oscillator acts as a receiver LO.  If you move around, the receiver gives off a tone proportional to velocity.

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