Microstrip antennas integrated with electromagnetic band-gap (EBG) structures: a low mutual coupling design for array applications

TLDR

The utilization of electromagnetic band‑gap (EBG) structures is increasingly attractive in the electromagnetic and antenna community. The paper analyzes a mushroom‑like EBG structure using the finite‑difference time‑domain method. The authors employ FDTD to study the EBG, parametrize mutual coupling of microstrip antennas across E and H planes with varying substrate thickness and dielectric constants, and insert the EBG between array elements to mitigate coupling. Simulations and measurements confirm that the mushroom‑like EBG suppresses surface waves, reducing mutual coupling by approximately 8 dB in the microstrip antenna array.

Abstract

Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. In this paper, a mushroom-like EBG structure is analyzed using the finite-difference time-domain (FDTD) method. 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 both 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. As a result, a significant 8 dB mutual coupling reduction is noticed from the measurements.