OPS243-C FMCW and Doppler Radar Sensor with WiFi/Bluetooth Interface - OmniPreSense
HanxiaoMeow on Twitter: "Found a 24Ghz FMCW radar module on Aliexpress, cost about 25USD. It looks like some sort of FR4, but is that possible to make 24Ghz Antenna on FR4? https://t.co/v93CAhoNP1" /