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


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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    • "The inductance and capacitance of the LC circuit are due to the current along adjacent vias and to the gap between the side by side metal patches, respectively. The parallel circuit LC at resonance has the impedance [2] "
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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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    • "According to research in [4], an LC-based branch-line hybrid coupler had been integrated with the antenna to decouple the ports. Utilizing EBG structures is an effective method to reduce the mutual coupling between antenna elements [5] [6] [7]. Two bent slits had been etched into the ground plane to improve isolation at lower frequency and widen impedance bandwidth at higher frequency [8]. "
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    • "Therefore, the isolation between antenna elements is one of the key issues for the design of the MIMO systems. A number of techniques have been reported to enhance the isolation of two antenna elements, they can be classified as the introduction of offsetting branches [6], [7], the usage of modified ground [8], the utilization of metamaterials [9]–[12], as well as the adoption of decoupling networks [13]. Regarding the four-element antenna system, the reported techniques include the utilization of decoupling networks [14]– [17], optimization of antenna system configurations [18], [19], introduction of metamaterial structures including split-ring resonators (SRRs) [20]–[22] and planar mushroom [23], as well as any combination of the decoupled methods mentioned earlier [24], [25]. "
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