Return Loss Bridge

A handy device for measuring relative impedance match is a return loss bridge.  I patterned my design after this one, a part of the fantastic Green Bay Professional Packet Radio web site.  This is a "must see" site if you are at all interested in radio experimenting.

My bridge was constructed using a surplus Emco power splitter.  I removed all of the existing descrete components, leaving only the PC board and three BNC connectors.  The PC board was almost a perfect match for this circuit, as the BNC connections were already soldered to the existing traces.  Surface mounted components were used for the parts directly in the RF signal path.  Two 100 ohm resistors in parallel were used to achieve the desired 50 ohm arms, as my junk box did not have anything close to this value.