Isolation Enhancement for $1\times3$ Closely Spaced E-Plane Patch Antenna Array Using Defect Ground Structure and Metal-Vias

Zicheng Niu,Qiang Chen,Hou Zhang,Tao Zhong

doi:10.1109/access.2019.2937385

Abstract

This paper introduces an effective solution for improving isolation in linear antenna array. The array is composed of three-element E-plane single feed patch antennas (the overall size is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.59\,\,\lambda _{0}\,\,\times1.02\,\,\lambda _{0}$ </tex-math></inline-formula> ), which are closely placed with approximately <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.037~\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the free-space wavelength at 4 GHz. The decoupling structure consists of T-shaped and rectangular ring shaped defect ground structure (DGS) with six metal-vias. The decoupling mechanism is illustrated by investigating the current vector on the ground plane. The current distribution indicates that the decoupling structure along the outer edge of the radiation patch sever as coupling current converter to produce reverse current opposite to the direction of the ground coupling current, which transmits along the outer edge of the radiation edge. The measured results show that the enhancement in the isolation at 4 GHz is 10.8 dB for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}21\vert $ </tex-math></inline-formula> , 17.5 dB for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}23\vert $ </tex-math></inline-formula> and 16.6 dB for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}31\vert $ </tex-math></inline-formula> . After applying the decoupling structure, the 10-dB impedance bandwidth (3.95 - 4.04 GHz) of antenna 1 remains unchanged. Meanwhile, the 10-dB impedance bandwidth of the antenna, which is located in the middle of the three-element antenna array, increases by 86 MHz (from 114 MHz to 200 MHz). When the decoupling structure is loaded, the maximum gain only decreases by 0.12 dB (from 3.94 to 3.82 dB). The decoupling structure has the advantages of simple structure, easy processing, and independent design of the array, so it can be applied to multielement patch array, such as massive multiple-input multiple-output (M-MIMO) system.

Highlights

With the development of multi-antenna system [1]–[3], electromagnetic wave interference between antennas has become one of the most concerned problems in array antenna design
In order to obtain high isolation in the closely spaced three-element antenna array, the defect ground structure (DGS) is etched along the outer edge of the radiation patch, which generates the current opposite to the coupling current to undermine the mutual coupling
The isolation between nonadjacent antennas – |S31| is increased by 15.6 dB at the center frequency

Summary

Introduction

With the development of multi-antenna system [1]–[3], electromagnetic wave interference between antennas has become one of the most concerned problems in array antenna design. Z. Niu et al.: Isolation Enhancement for 1 × 3 Closely Spaced E-Plane Patch Antenna Array Using DGS and Metal-Vias general method for the size and connection position of the neutralization line, so the simulation software can only be used for tuning and optimization of the neutralization line and antenna, which increases the design time and difficulty.

Results

Conclusion