Your radar tells you their position, heading and speed. Their radar detector tells them you're out there somewhere. They have no direction finding activity. There is no magic scope showing them the same blip on a screen you see. All they can say is "Yep, there's a radar out there somewhere." Advantage you!
Leave the blasted thing on 24 hours a day. When they detect you it only scares them because they know what follows the radar signals.
