Coplanar waveguide method for identifying the surface wave band-gap range of mushroom-like electromagnetic band-gap structure
In this paper, coplanar waveguide (CPW) method is proposed for identifying the surface wave band-gap of mushroom-like EBG structure. Two lines are cut off from the complete ground plane of the EBG structure and the defected ground plane can be viewed as a coplanar waveguide with characteristic impedance of 50 Ohm. The other layer of the EBG structure is not changed. The surface wave band-gap range can be obtained from the transmission curve of CPW in two cases: EBG inserted and no EBG inserted. Furthermore, the electric field distribution within and beyond the stop-band are studied. And we also investigate the influence of EBG rows on the band-gap. The results extracted from CPW method agrees very weD with that of TEM waveguide model. Compared to the most used experimental method, suspended microstrip line method, the CPW method is a one-layer structure which leads to be low-cost, easy-made and more effective. Both simulated and experimental results verify the effectiveness of the CPW method. Therefore, the CPW method can be applied for identifying the surface wave band-gap of EBG structure much more effectively in engineering applications.