A Millimeter-Wave Fabry–Perot Cavity Antenna With Unidirectional Beam Scanning Capability for 5G Applications

In this article, a millimeter-wave (mmW) leaky-wave antenna (LWA) with unidirectional beam scanning (UBS) capability based on the Fabry–Perot cavity (FPC) structure is proposed for fifth-generation (5G) applications. The proposed antenna consists of a main radiating element, a metallic wall, a ground plane, and a single-layer partially reflective surface (PRS). To improve the UBS performance, a single radiating element is designed such that it provides a tilted beam with good radiation performance over the scanning angles. The metallic wall is used close to the radiating element as a reflector to suppress the propagation in undesired directions. A general design guide is given by a theoretical analysis of the FPC structures using the ray-tracing method to formulate the beam-steering functionality versus frequency over desired predetermined angles. The PRS layer is designed without any tuning elements to provide the beam scanning over the angles of $10^\circ < \theta < 45 ^\circ $ and the frequency range of 24–30 GHz. The proposed Fabry–Perot cavity antenna (FPCA) structure is fabricated and the measurement results show a beam steering from 19° to 54° over the frequency band from 24 to 30 GHz, which is in good agreement with the calculated results from the theoretical analysis. A maximum measured gain of 14.5 dBi at 24 GHz is achieved. The proposed antenna can be used in the 5G mobile communication systems and 5G base station antennas (BSAs), where beam steering with high-gain and low fabrication cost features over the mmW spectrum is required.

I. Introduction

The demand for high-traffic capacity and speed in wireless communication systems led to the fifth-generation (5G) technology. The millimeter-wave (mmW) band has always been attractive for mobile communications and is a suitable candidate for 5G applications. In particular, frequency band across 26–29 GHz is used for local multipoint distribution service (LMDS) and future 5G base station antennas (BSAs). However, the mmW spectrum suffers from propagation issues, such as high loss and interference. These concerns can be mitigated by increasing the gain of the antennas and performing beam scanning simultaneously. Phased array antennas and lens antennas are among those, which have been studied to overcome the mentioned problems [1]–[4]. However, their bulky structures and high fabrication cost might restrict their applications. Leaky-wave antennas (LWAs) have been studied as a suitable alternative to provide directive beam scanning versus frequency [5] or at a fixed frequency [6].