A Low-Profile Dual-Layer Patch Antenna with a Circular Polarizer Consisting of Dual Semicircular Resonators

Li Guo,Mei Li,Ming-Chun Tang

doi:10.3390/s18061773

Abstract

In this paper, a circular polarizer comprising dual semicircular split-rings (DSSRs) is presented. By placing it above an elliptical radiator that radiates linearly polarized (LP) waves, dual-layer patch antennas capable of radiating right-hand (RH) or left-hand (LH) circularly polarized (CP) waves are achieved in terms of the different offset direction of the bottom splits of the DSSRs. Because of both the capacitive coupling to the radiator and the degenerate modes existing in the excited DSSRs, the DSSRs collaboratively result in a circularly polarized radiation, successfully converting incident LP waves into CP ones. Simulated results show that the impedance, axial ratio (AR), and gain frequency response of both proposed CP antennas are identical, with a simulated 3-dB AR bandwidth of 72 MHz covering 2.402–2.474 GHz and a gain enhanced by 3.9 dB. The proposed antennas were fabricated and measured, revealing an operational bandwidth of 65 MHz (2.345–2.41 GHz) and a peak gain up to 9 dBi. Moreover, a low profile of 0.063λ0 is maintained. The proposed CP antennas could be as a candidate for wireless target detection applications in terms of their identical frequency response property.

Highlights

Contemporary wireless communications are steering to large capacity, integrated functions, and high reliability
The proposed circularly polarized (CP) antennas could be as a candidate for wireless target detection applications in terms of their identical frequency response property
This paper presents a dual-layer CP patch antenna with a circular polarizer that contributes to the polarization transformation from an linearly polarized (LP) wave to a CP one

Summary

Introduction

Contemporary wireless communications are steering to large capacity, integrated functions, and high reliability. Multipath reflection and polarization mismatching between the transmitters and receivers make communications that apply LP antennas unreliable [1]. CP antennas can transmit/receive LP waves in an arbitrary direction or sense identical CP waves, which significantly lowers the transmission blocking caused by polarization inconsistency [2]. In a wireless target detection field, an electromagnetic wave is usually utilized in a manner that captures the reflected/scattered wave from targets, representatively operated as radars [5]. In many situations, the objective/goal may be knowing a target’s state, such as its location or orientation, but it is difficult to obtain the environmental characteristics surrounding targets, such as background or obstacles, which could provide a more comprehensive understanding of targets [6]

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