antenna-theory.com

[Joesixty]

Hello, I've recently found your antenna-theory site and this forum. Thanks for doing this. I'm searching for a way to improve a small radar sensor I'm using. I looked first at all the existing posts, but didn't find a related item.
I'm using the HB100 Doppler motion sensor radiating at 10.525 GHz. http://www.limpkin.fr/public/HB100/HB100_Microwave_Sensor_Module_Datasheet.pdf https://www.tindie.com/products/limpkin/hb100-doppler-module-with-backpack-1
The sensor, with its associated backer board amplifier, puts out a logic level square wave of the Doppler frequency reflected from moving targets.

My first goal is to minimize the antenna sensitivity to motion from behind it and to the sides and top. The second goal is to perhaps improve the detector's range in the forward direction. I've considered both corner reflectors and horns, and I could use your expert opinions here since this is something of an unusual problem for me.

All the examples and formulas for horns that I've seen expect the signal to be delivered to the horn from a waveguide. Could I just place the sensor inside a horn of proper dimensions and get the improvements I need?

Corner reflectors all show the antenna at 1/2 wavelength from the corner. Since I have this fixed circuit board with offset antennas, plus a Doppler signal amplifier built on a circuit board behind the radar board, I can't get close enough to make the 1/2 wavelength, and I'm worried about what an arbitrary distance could do to the antenna impedance. Is there a way to modify the corner reflector concept in this situation?
Thanks for any advice in advance.