Radar design with single antenna (monostatic)

Hi, for a radar design with a single Tx/Rx antenna, a circulator is normally used...

The question is -- are there any other ways to accomplish a single antenna with simultaneous Tx/Rx? A circulator is very impractical for surface-mount type technology...

Thanks!

A sp2t switch would work IF the target is sufficiently far away and it was not a cw radar.

Narrowband, you could probably do something with printed line couplers or a rat race design to have tx show up at the antenna, and rx go to the receiver. You will need good impedance matches on all ports to get any isolation though.

This is a fmcw narrowband (24 GHz) system.

Any references or more thoughts on the coupler/rat race designs? I'm thinking of a 3-layer board, SMT circuitry (one side), common ground plane (middle), patch antenna (other side) and obviously a circulator is not really compatible with SMT components for the circuit side...

Thoughts?

What is your target distance?

It's actually very short, we want to use this as a reflectometer. So say ~2-3 ft?

This is one of the reasons that I don't want to use two antennas...

Any thoughts?