Compensation of superstrate effects on the resonant behavior of the microstrip ring structure by using an air-gap control

In this paper, spectral-domain analysis is utilized to investigate the possibility of compensation of superstrate shielding effects on the resonant behavior of the microstrip ring structure by means of an adjustable air-gap inserted between the substrate and the ground plane. In order to provide the desired amount of tuning, the adjustment of the proper gap thickness is discussed for various structural parameter cases. It is shown that the resonant frequency shift due to superstrate shielding can be compensated, the resonant bandwidth and, hence, the electromagnetic interference can be directly controlled resulting of the proposed tuning scheme.