Efficient FDTD analysis of conductor-backed CPWs with reduced leakage loss

Leakage loss of the conductor-backed coplanar waveguide (CBCPW) is analyzed by using a novel hybrid two-dimensional finite-difference time-domain/Marquardt curve fitting technique. The validity and high accuracy of the method is confirmed by comparison with other experimental and theoretical results. A modified CBCPW structure with a substrate groove in the backside is proposed, which shows over eight times smaller leakage loss than a normal CBCPW.