Article

Microstrip Antennas Integrated with Electromagnetic Band-Gap (EBG) Structures: A Low Mutual Coupling Design for Array Applications

Dept. of Electr. Eng., Univ. of California, Los Angeles, CA, USA
IEEE Transactions on Antennas and Propagation (Impact Factor: 2.18). 11/2003; 51(10):2936 - 2946. 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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    ABSTRACT: A double element 900 bent monopole antenna system with mushroom-like electromagnetic band-gap (EBG) structures introduced between elements has been studied in this paper using a Finite Element Method (FEM) in order to demonstrate the concept of EBG mutual decoupling. The EBG structures were designed to have a band gap centered around the bandstop frequency of 2.45 GHz. The mutual coupling coefficient s21 was simulated over a range of frequencies around the band gap for some specific designs and electric field distribution on XY plane for optimal EBG design was also computed. Inserting a number of five EBG unit cells with patch sizes of 8 mm, gap between patches of 4 mm and vias cross sectional area of 3.515 mm2, the mutual coupling between antennas improved from-24 dB to-37.4 dB at bandstop resonance frequency of 2.45 GHz.
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