Methods and apparatus related to a LED-based lighting unit (10; 110; 210; 310; 410) having a radar for presence detection. A radar circuit (140; 240; 340A; 340B; 440) may be electrically coupled to conductive wiring (25; 125; 225; 325; 425) of the LED-based lighting unit that at least selectively powers the radar circuit and at least selectively powers the LEDs. In some implementations, an antenna coupled to the radar circuit may be formed from the conductive wiring and optionally at least partially isolated from any current flowing through the LEDs.