Dutch Amateur / Ham Radio operator Peter Knol PA1SDB has enabled a 10 GHz transmitter with weak software beacon Opera, costing €3.
Peter describes how he used the €3 HB100 Miniature Microwave Motion Sensor which is an X-Band Bi-Static Doppler transceiver module. Using the free Opera software and dish antennas he was able to decode the 10 GHz signal at distances up to 32km.
Read the article in Google English - http://tinyurl.com/10GHz-for-3Euros
Article in Dutch - http://home.deds.nl/~knol/HB100/
Opera - https://rosmodem.wordpress.com/