Study of the Deleterious Effect of Common-Mode Behavior on CPS Branch-Line Couplers and Wilkinson Dividers

An experimental study into the design and measurement of a balanced Branch-line coupler and Wilkinson divider using coplanar strip (CPS) transmission lines is presented. While these balanced passive components show great potential for differential microwave signal processing applications, it is shown that their undesirable common-mode behavior needs to be addressed for them to be of any use in practice. Some techniques for doing this are proposed based on results from mixed-mode S-parameter investigations.