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

• ##### Y. Rahmat-Samii
Dept. of Electr. Eng., Univ. of California, Los Angeles, CA, USA
IEEE Transactions on Antennas and Propagation (Impact Factor: 2.33). 11/2003; DOI: 10.1109/TAP.2003.817983
Source: IEEE Xplore

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.

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##### Article: A Novel and Simple Analytical Method for Analysis of AMC and EBG Properties of Lossless Artificial Impedance Surfaces
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ABSTRACT: In this paper, a novel and simple analytical method for analysis of AMC and EBG properties of a typical lossless artificial impedance surface (AIS) is investigated. The main con-tribution of the paper is to demonstrate that AMC and EBG behaviorsof an artificial impedance surface can be characterized analytically with using reflection coefficient for both TE and TM polarized oblique incidence plane waves. It is shown that the AMC properties (when the reflec-tion phase varies in between +90 and −90 degrees) of an impedance surface can be obtained from reflection phase and EBG properties (stop bands for TE and TM surface wave modes) from poles of reflection coefficient. We have derived closed analytical formulas for the impedance surface and reflection coefficient for TE and TM waves for two conventional impedance surfaces such as: grounded dielectric slab and grounded dielectric slab with embedded metallic vias (wired media). The analytical results are verified with numerical simulations.