Radar

Doppler
http://www.ebay.com/itm/HB100-Microwave-Sensor-Module-10-525GHz-Doppler-Radar-Motion-Detector-Arduino-/171297069092

https://www.youtube.com/watch?v=2RXSVBzEs14 RCWL-0516 RCWL 0516 Microwave Radar Sensor, human. On aliexpress for $1. Range about 5m, which compares well with pet safe passives. Avoid radar signature interference when installing multiple units. See OutdoorBox

Radar Sensor Module Wireless HB100 Microwave Doppler Radar Detector Probe Wireless Sensor Module 10.525GHz from Aliexpress.com shop  ModuleFans  $2.65. attach to satellite dish 10m range

https://www.youtube.com/watch?v=9WiJJgIi3W0 radar burglar detection review of five different modules.

https://github.com/jdesbonnet/RCWL-0516   Information about RCWL-0516 microwave proximity switch module (ICStation.com SKU 10630

self driving cars
77ghz radar modules used in self driving cars are mass produced, reducing costs. Range is 150m

journals
https://www.hindawi.com/journals/ijmst/2014/958905/ A multifrequency radar system for detecting humans and classifying their activities at short and long ranges is described. The short-range radar system operates within the S-Band frequency range for through-wall applications at distances of up to 3 m. It utilizes two separate waveforms which are selected via switching: a wide-band noise waveform or a continuous single tone. The long-range radar system operating in the W-Band millimeter-wave frequency range performs at distances of up to about 100 m in free space and up to about 30 m through light foliage. It employs a composite multimodal signal consisting of two waveforms, a wide-band noise waveform and an embedded single tone, which are summed and transmitted simultaneously.

marine radar
https://www.sea-hawk.com/Small-target-detection/default.aspx If you are looking for superior small target detection for your vessel or for your offshore location, a polarimetric radar antenna should be your best choice. The Sea-Hawk radar is your future small target detection system. Sea-Hawk polarimetric radars are multi polarized, resulting in far more detailed detection ability than traditional radar systems. Sea-Hawk can detect very small, and even fast moving, objects and would therefore raise your small target detection capabilities to a level you could only dream about until recently.

RCWL-0516 RCWL
https://www.youtube.com/watch?v=rgVu9n_j9pM 10 ZAR for one 3.2ghz radar sensor(no heat). pInout diagram given.

Surveillance radar

 * https://en.wikipedia.org/wiki/Compact_surveillance_radar hack these Patents held by five companies.
 * https://spotterrf.com/ https://www.google.com/patents/US20150204969 A method for determining location information for a target may include generating a cyclic transmit signal having a fixed frequency slope over a substantial portion of each cycle and an operational frequency that is selected to penetrate foliage, transmitting the cyclic transmit signal without up-conversion with at least one transmit antenna, down-converting two or more return signals received from corresponding return antennas with the cyclic transmit signal to provide a corresponding set of baseband signals, extracting magnitude and phase information for each return signal as a function of range from the plurality of baseband signals, and determining a location of a target from the magnitude and phase information. A corresponding apparatus, system, and computer readable medium are also disclosed herein.
 * http://www.magosys.com/
 * http://www.geolux.co.za/Products/

dashcam radar
Podofo Car DVR Camear Radar Detector GPS 3 in 1 Ambarella Car-detector LDWS HD 1080P Recorder Registrar Anti Radar Dashcam WDR.