Return Loss Bridge

The return loss bridge is a handy tool to have in the RF lab.  Lately the wide availability of inexpensive hobbyist grade VNA's have made it less relevant, but there definitely still are occasions where it is useful.

I made mine from a decades old simple design.  The results turned out great.  Check out the episode on YouTube:

Watch the episode

The circuit files below actually contain two designs - the bridge itself, plus a simple diode detector.  I didn't cover the detector in the episode.  It simply rectifies the RF energy sampled at the bridge detector port, letting you measure the result as a simple DC voltage.  If you only want to make the bridge, just delete the detector from the schematic and the board layout.

Below are downloadable files for this project.  Enjoy!

RLB KiCad Files

RLB LTSpice sim

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