A discussion on the coupling effects in conductor-backed coplanar waveguide MICs with lateral sidewalls

It is pointed out that a conductor-backed coplanar waveguide (CBCPW) with lateral sidewalls can support rectangular waveguide modes that couple with the dominant mode and can produce some undesirable results. These modes can be cut off by reducing the lateral dimensions of the structure, but for higher frequency operation the available circuit surface area is severely limited. The CBCPW is analyzed with a two-dimensional spectral domain method to demonstrate these coupling effects. The results provide insight into the characteristics of finite-length structures. In addition, experimental data demonstrate the coupling effects within a CBCPW.<>