I am looking for possible ways to measure s-parameters of a 3-port power splitter (1 input and 2 outputs). It is similar in concept to a wilkinson, but also provides matching and none of the ports are 50 ohms. A parallel matching network would probably be the correct thing to call it. Measurements will be taken on wafer, from 1-60GHz.
There are three options I know of. One is to terminate one of the ports with 50ohms and take 2-port measurements. The second option is to take a 3-port measurement. Since the outputs are symmetric and no odd mode exists, the third option would be to short the outputs to create a 2-port.
The problem is, the two output traces are about 10-20 times the width of a 50ohm line, with spacing near the minimum allowed. If I connect to the output ports with a wide line or taper, I'll have moding and coupling errors. If I connect to them with a 50ohm line, I'll get errors due to the large step in width.
I'm considering placing two identical splitters back to back and taking a 2-port measurement. The outputs of each splitter would simply be shorted together, solving the wide line issue. I have done this in the past with langes, phase shifters, and other structures, but never tried to extract the parameters of one structure.
I feel like there's a way to extract 3-port s-parameters from the 2-port measurement, since the structures are mirrored and symmetrical. I have found plenty of papers that reference info from back to back measurements, but I can't find any that try to deembed to a single structure.
Can 3-port s-parameters be extracted from my 2-port measurement? It may not be possible to create a full 3-port matrix, but which s-parameters could be extracted?