A high gain pattern stabilized array antenna fed by modified Butler matrix for 5G applications

Abstract

In this work, a beam-steering array antenna with the aim of pattern stabilization is presented. The antenna element consists of three-layer and a unique structure of the metalized via hole. It is capable to cover the frequency range from 20.5 to 30 GHz and a stable pattern over thorough operation frequencies. Moreover, the element has a constant gain with the peak of 9.5dBi. Additionally, the proposed modified Butler matrix consists of two 90-degree and two 135-degree couplers without phase shifting section to attain a pattern stabilized beam-steering array antenna. The proposed Butler matrix manages patterns in a constant phase over a frequency from 21 to 29 GHz with the phase error less than ±6°. The integration proposed element and feed network lead to a beam-tilting array antenna which can manage its patterns via input ports and maintain direction by frequencies variation range between 21.1 and 28.8 GHz.