Leakage phenomena in multilayered conductor-backed coplanar waveguides

Leakage phenomena possible in the multilayered conductor-backed CPWs are investigated using the spectral domain technique with a complex root searching procedure. The obtained phase and attenuation constants confirm that the leakage is due to the presence of parallel plate mode which is slower than dominant CPW mode. It is found that the leakage can be controlled by introducing an additional dielectric layer. Two different multilayered structures are given as examples. >