Mode conversion due to discontinuities in modified grounded coplanar waveguide

Modified grounded coplanar waveguide (CPW) is the same as conventional grounded coplanar waveguide except that the side planes are not of infinite extent. This structure is overmoded, but is still used in monolithic circuits since it does not require via holes. Conversion from the desired CPW mode to an undesirable microstrip-like mode is calculated using a full-wave analysis. The results indicate that mode conversion occurs at discontinuities, but that it is a small effect. In very-high-Q circuits, resonances may occur due to this coupling, but this conversion can be made small for reasonable structural dimensions.<>