Performance Enhancement in Compact Inverted-L Antenna by Using 1-D EBG Ground Structures and Beam Directors

Jae-Yeong Lee,Jaehyun Choi,Jae-Hyung Jang,Wonbin Hong

doi:10.1109/access.2019.2927738

Abstract

This paper describes a compact inverted-L antenna (ILA) topology that can enhance antenna performance by utilizing one-dimensional electromagnetic bandgap (1-D EBG) ground structures and two-stage beam directors. The antenna is fed through the coaxial connector and the microstrip line, and the 1-D EBG structures are embedded on the ground plane edge of the microstrip line that is closer to the planar ILA. The 1-D EBG ground structures serve as high impedance surfaces with slow-wave behavior controlling both reflection phase in plane-wave illumination and surface-wave on the horizontal-direction of the ground plane edge. The proposed antenna with 1-D EBG ground structures exhibits a wide impedance bandwidth of 810 MHz between 2.24 GHz and 3.11 GHz within a compact size of 0.21λ 0 × 0.32λ 0 . In addition, the endfire radiation performances in horizontal-polarization of the designed antenna can be enhanced without any supplementary circuits by the integration of 1-D EBG structures within compact real-estate and by placing beam directors. As the criterion for improvement of the radiation pattern, the horizontally polarized end-fire gain of 4.0 dBi and radiation intensity difference between co-polarization and cross-polarization of 14.0 dB toward the end-fire direction are experimentally ascertained.

Highlights

For high-speed and high-capacity communications beyond the physical threshold properties of active RF devices in microwave and millimeter-wave applications, compact planar antennas with robust performance have been devised [1], [2]
When the AiP is implemented on low temperature co-fired ceramics (LTCC) or multilayer PCBs such as high-density interconnect (HDI) FR-4 laminations, the 3-D interconnect loss, i.e. feasible dimension of via hole, is the critical issue of antenna performance
On the front side edge of the ground planes that is near the planar inverted-L antenna (ILA), a 1-D Electromagnetic bandgap (EBG) structure with seven periodic cells is patterned in one column to serve as high impedance surfaces with slow-wave behavior

Summary

INTRODUCTION

For high-speed and high-capacity communications beyond the physical threshold properties of active RF devices in microwave and millimeter-wave applications, compact planar antennas with robust performance have been devised [1], [2]. With 0.03λ0 spacing between ILA and 1-D EBG, the 1-D EBG ground structures serve as high impedance surfaces with slow-wave behavior featuring quadratic reflection phase for impedance matching and high end-fire gain. To ascertain the effect of the 1-D EBG ground structures in the proposed antenna, the reflection coefficients, radiation patterns, and near-field distributions are compared using various antennas such as ILA without 1-D EBG and PIFA without 1-D EBG Because these characteristics of 1-D EBG ground structures can overcome the drawback of additional circuits that limit antenna impedance bandwidth, ILA topology with 1-D EBG ground structures can exhibit broad bandwidth and high gain. On the front side edge of the ground planes that is near the planar ILA, a 1-D EBG structure with seven periodic cells is patterned in one column to serve as high impedance surfaces with slow-wave behavior. By comparing the substrate with and without 1-D EBG structures, the calculated reflection phase exhibits relatively steep phase changes due to the effect of the

GROUP DELAY OF 1-D EBG GROUND STRUCTURES

CONCLUSION