Effects of the bottom ground plate on coplanar waveguide structures

Abstract

In this article, the authors study the significant practical effects caused by the presence of a conductor plate beneath a coplanar waveguide (CPW) structure. Specifically the authors pay attention to the effects on the dispersion characteristics of the bound modes and on the signal integrity. This study allows one to discuss the reported proposal on the use of this additional conductor plate as an inexpensive alternative to air‐bridges in order to alleviate the possible spurious effects produced by the potential existence of asymmetries in CPW‐based circuits.

Width‐varying conductor‐backed coplanar waveguide‐based low‐pass filter with a constant signal trace to adjacent grounds separation

“…low‐pass filtering characteristics). CB‐CPW is selected over the conventional CPW configuration to avoid unwanted propagation modes at discontinuities such as the coupled slotline mode that degrades signal integrity and requires air‐bridging [15]. CB‐CPW‐based width‐varying profiles are established based on systematic mathematical guidelines, and are optimised using evolutionary optimisation techniques to solve the resulting complex bound‐constrained non‐linear equations, which will be discussed in greater details in Section 2.…”