Butler Matrix Based Beamforming Networks for Phased Array Antenna Systems: A Comprehensive Review and Future Directions for 5G Applications

Arshad Karimbu Vallappil,Noor Asniza Murad,Mohammed Gajibo Mustapha,Mohamad Kamal A Rahim,Bilal A Khawaja

doi:10.1109/access.2020.3047696

Abstract

Due to the rapid development of wireless communication technologies, the number of wireless users are radically increasing. Currently, ~23 billion wireless devices are connected to the internet, and these numbers are expected to increase manifolds in the years to come. The technology growth of the fifth-generation (5G) wireless systems will be needed to meet this high demand of the network. 5G wireless systems offer data-rates of up to 10Gbps, 1-ms latency, and reduced power consumption. It is a known fact that 5G wireless systems will be exploiting beyond the presently used 3 GHz microwave and millimetre-wave (mm-wave) frequency bands. This is the primary driver in the development of the 5G wireless system. Multi-beam Phased array antenna (PAA) systems are typically used in the deployment of 5G systems for high-gain and directionality. In current 5G and future Beyond 5G (B5G) antenna array systems, beamforming networks (BFNs) such as the Butler Matrix (BM) will play a key role in achieving multi-beam characteristics. So, this paper presents an extensive review of the BM based BFNs, and discusses which type of BM will be suitable for the phased array antenna (PAA) systems in the upcoming 5G and next-generation of B5G wireless systems. Moreover, this paper also summarizes the different types of BM designs based on the number of layers. The BMs are classified into the bi-layer, tri-layer, and four-layer structures. It includes different techniques that have been used to solve the problem of crossing, narrow bandwidth, and size reduction of the BM. From the previous studies, it is found that most of the past research work was performed using the bi-layer BM system, whereas the difficult geometries like tri- and four-layer BM are avoided due to their complex fabrication process. It is also found in this paper that the metamaterial (MTM) based bi-layer BM achieves low insertion-loss and phase-error, excellent bandwidth and compact size, and good S-parameter performance, which makes them an ideal BFN candidate for the upcoming 5G and next-generation B5G systems.

Highlights

Multi-beam antennas have been at the forefront of modern wireless communications for the last two decades [1]–[7]
The phased array antenna (PAA) system with multi-beam antennas is considered an ideal candidate for the 5G wireless systems and mobile terminals [8], [11], [12] to achieve both wide coverage and high-gain
As stated in [11] and [12], the PAA system is used to achieve multiple beams and decent coverage performance, but expensive transmitter/receiver (T/R) modules and the complexity of the PAA hardware design are some of the significant factors that needs to be taken into account

Summary

Introduction

Multi-beam antennas have been at the forefront of modern wireless communications for the last two decades [1]–[7]. Multi-beam and beam-scanning antennas play a key role in modern wireless communication systems to get the desired output. In many applications, such as WLANs [9], basestations [10], satellite communications [10], and even automotive radars [6], the multi-beam antennas concept has. The PAA system with multi-beam antennas is considered an ideal candidate for the 5G wireless systems and mobile terminals [8], [11], [12] to achieve both wide coverage and high-gain. For practical usage and large-scale deployment, it is essential that the feed networks for the PAA systems are low in profile and fabrication cost

Objectives

Findings

Conclusion