Hi

I would like to detect motion in a certain area, such as someone walking past.

Traditional you could use PR sensor, but these are bulky.

Has anyone used radar or a time of light sensor for such application in the past?

 

Czuinik mikrofalowy at Allegro or microwave proximity sensor at Aliexpress and/or ebay. Just push the knob and choose should it be 12 V or 220 V. https://nowodvorski-lampy.pl/eng_pl_Mikrofalowy-czujnik-ruchu-bialy-20853_1.jpg One knob adjusts the distance in what it feels human, other for time how long the lamp shines after human is detected, and third - how dark must be let it detects night - thus lamp shines interrupted.