A Millimeter-Wave Wideband Circularly Polarized Planar Spiral Antenna Array with Unequal Amplitude Feeding Network

Huakang Chen,Zhangjian He,Changhong Zhang,Yu Shao,Zhizhong Zhang,María Elena De Cos Gómez

doi:10.1155/2021/9955502

Abstract

A 2 × 2 wideband circularly polarized (CP) antenna array operating at millimeter wave (mmWave) band is presented. The array element is a wideband CP Archimedean spiral radiator with special-shaped ring slot. The elements are fed by an unequal amplitude (UA) feeding network based on a microstrip line (MSL) power divider. The side lobe level is improved by this UA feeding network. In addition, a cross slot is employed to isolate the elements for decoupling. A prototype is fabricated, and the measured results show that the proposed array achieves an impedance bandwidth (IBW) of 6.31 GHz (22.5% referring to 28 GHz) and an axial ratio bandwidth (ARBW) of 7.32 GHz (26.1% referring to 28 GHz). The peak gain of the proposed array is 11.3 dBic, and the gain is greater than 9.3 dBic within the whole desired band (from 25 GHz to 31 GHz). The proposed array consists of only one substrate layer and can be built by the conventional printed circuit board technology. Attributed to the characteristics of wide bandwidth, simple structure, low profile, and low cost, the proposed antenna array has a great potential in mmWave wireless communications.

Highlights

With the rapid popularization of the fifth-generation (5G) wireless communication technology and the growth of wireless data traffic, millimeter wave communication has become one of the most attractive technologies in the 5G mobile communication system [1]
In a typical sequentially rotated phase (SRP) feeding array, four single-feeding radiation elements are rotated clockwise or anticlockwise, and the elements are fed with equal amplitude and 90 degrees phase difference. e SRP feeding technique is beneficial to improve the bandwidth and polarization purity of circularly polarized (CP) array. e reported structures of SRP feeding network in the mmWave band can be divided into three categories: (1) microstrip line (MSL) SRP feeding network [2,3,4,5], (2) substrate-integrated waveguide (SIW) SRP feeding network [6,7,8,9], and (3) grounded coplanar waveguide (GCPW) SRP feeding network [10, 11]
A prototype is fabricated to verify the proposed 2 × 2 mmWave wideband CP array based on the parameters shown in Tables 1 and 2. e prototype is fabricated by using the printed circuit board (PCB) technology which has a low cost. e array is connected with a 50 Ω southwest microwave 2.92 mm end launch connector for measurement

Summary

Introduction

With the rapid popularization of the fifth-generation (5G) wireless communication technology and the growth of wireless data traffic, millimeter wave (mmWave) communication has become one of the most attractive technologies in the 5G mobile communication system [1]. A low-profile cavitybacked slot CP 2 × 2 array and a 2 × 2 wideband RHCP diamond ring slot antenna array at the X-band were realized by employing the SIW SRP feeding network structure in [6, 7], respectively.

Results

Conclusion