Abstract: In this paper, a mushroom-like EBG structure is analyzed using the finite-difference time-domain (FDTD) method. Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. Its band-gap feature of surface-wave suppression is demonstrated by exhibiting the near field distributions of the electromagnetic waves. The mutual coupling of microstrip antennas is parametrically investigated, including the E and H coupling directions, different substrate thickness, and various dielectric constants. It is observed that the E-plane coupled microstrip antenna array on a thick and high permittivity substrate has a strong mutual coupling due to the pronounced surface waves. Therefore, an EBG structure is inserted between array elements to reduce the mutual coupling. This idea has been verified by both the FDTD simulations and experimental results.
Keywords: Electromagnetic band-gap (EBG), finite-difference time-domain (FDTD) method, microstrip antennas, mutual coupling, surface wave.