Dual CP Polarization Diversity and Space Diversity Antennas Enabled by a Compact T-Shaped Feed Structure

Junping Geng,Guanshen Chenhu,Xianling Liang,Richard W Ziolkowski,Kun Wang,Ronghong Jin,Xiaonlan Zhao,Han Zhou

doi:10.1109/access.2019.2925396

Abstract

A compact T-shaped feed structure (TFS) is reported that enables the realization of two types of diversity antennas: a polarization diversity antenna (PDA) and a spatial diversity antenna (SDA). Both systems have a high potential for mobile wireless communication applications. The TFS includes four ports and two independent coaxial channels with effective isolation between them all. The PDA is a dual CP omnidirectional antenna. Its optimized prototype achieves measured impedance bandwidths of 16.4% and 15.28% in its LHCP and RHCP states, respectively, and realized gains in both between 4.8 and 6.46 dBic. The inner thin coaxial cable (ITCC) of the TFS directly drives its LHCP subsystem, facilitating its improved omnidirectional performance. This ITCC is also used to directly feed the SDA’s low-profile directional planar equiangular spiral antenna and its side port drives its omnidirectional RHCP antenna. Good hemispherical coverage is realized with a measured common impedance bandwidth larger than 14.35% with more than 40-dB isolation between its two ports. The corresponding measured realized gain of the SDA is between 4 and 7.8 dBic. The measured results for both optimized prototypes confirm their simulated performance characteristics.

Highlights

With the rapid development of mobile wireless communication systems, such as wireless ad hoc networks, there has been strong interest in polarization diversity (PDA) and spatial diversity (SDA) antennas
VOLUME 7, 2019 is a greatly improved version of the design in [18]. It is compact and realizes two independent, effectively isolated channels. It is combined with an omnidirectional Circular polarization (CP) slot array antenna (OCPSA) to realize an improved dual CP omnidirectional antenna (DCPOA)
This polarization diversity antenna (PDA) is fed from only two ports of the T-shaped feed structure (TFS) and radiates both LHCP and RHCP fields

Summary

INTRODUCTION

With the rapid development of mobile wireless communication systems, such as wireless ad hoc networks, there has been strong interest in polarization diversity (PDA) and spatial diversity (SDA) antennas. It was found that connecting the feed wire to the LHCP port from the outside negatively affects the radiation pattern when the antenna is mounted vertically on the roof of a metallic vehicle As a result, it does not achieve omnidirectional radiation and its CP characteristics are lost in some azimuth directions. It is combined with an omnidirectional CP slot array antenna (OCPSA) to realize an improved dual CP omnidirectional antenna (DCPOA) This PDA is fed from only two ports of the TFS and radiates both LHCP and RHCP fields. One channel of the TFS feeds its OCPSA; another channel is connected through the ITCC to a low profile directional antenna mounted on top of it This arrangement realizes horizontal omnidirectional fields and fields radiated directionally upwards.

TFS IMPEDANCE TRANSFORMATION

CONCLUSION