A Wideband Circularly Polarized Antenna with Characteristic Mode Analysis

Abstract

A wideband circularly polarized (CP) antenna is presented to achieve enhanced impedance, axial ratio (AR), and gain bandwidths. The antenna consists of two circular patches, a split-ring microstrip line with six probes, and a circular ground plane. By using these six probes which are placed in sequence on the split-ring microstrip line, the operating bandwidth of the proposed antenna is increased. The characteristic mode method is used to analyze different modes of the antenna and reveal the mechanism of extending the 3-dB AR bandwidth. Measured results show that the proposed antenna obtains an impedance bandwidth of 1.486–2.236 GHz (40.3%) for S11 ≤ −18 dB, a 3-dB AR bandwidth of 1.6–2.2 GHz (31.6%), and a boresight gain of 8.89 ± 0.87 dBic.

Compact Broadband Circularly Polarized CPW-Fed Antenna with Characteristic Mode Analysis

“…Furthermore, [19] indicates how to place the antenna on the structure to excite specific mode(s). With the help of CMA, various CP antennas have been proposed with characteristics of performance enhancement [20], simple design procedure [21], wideband [22], stacked patch with multiple probes [23], and low profile and high directivity [24].…”

Design of multimode broadband circularly polarized antenna using characteristics mode analysis

“…Harrington and Mautz gave the initial definition of characteristic mode theory (CMT) in 1971 by studying the operator equations for currents and then they used the CMT to study radar scattering patterns 16–18 . Recently, many researchers have used the characteristic mode analysis (CMA) to analyze the antenna working principle and supplement the physical insights and concepts of antenna design 19–26 . In Ref.…”

“…Furthermore, a clock‐shaped CPA is designed using the CMA to achieve the impedance bandwidth from 2.38 to 5.8 GHz and the 3‐dB ARBW from 2.4 to 3.73 GHz 24 ; in Ref. 25, a polarization‐dependent metasurface antenna using the CMA is designed to achieve the impedance bandwidth of 29.11% and the 3‐dB ARBW of 9.02%; based on the CMA, a circular antenna consists of a split loop microstrip line and six probes to achieve the impedance bandwidth of 40.3% and the 3‐dB ARBW of 31.6% 26 …”

“…[16][17][18] Recently, many researchers have used the characteristic mode analysis (CMA) to analyze the antenna working principle and supplement the physical insights and concepts of antenna design. [19][20][21][22][23][24][25][26] In Ref. 19, the CP mechanism of a U-slot antenna and an E-shaped antenna is explained using the CMA.…”

“…25, a polarization-dependent metasurface antenna using the CMA is designed to achieve the impedance bandwidth of 29.11% and the 3-dB ARBW of 9.02%; based on the CMA, a circular antenna consists of a split loop microstrip line and six probes to achieve the impedance bandwidth of 40.3% and the 3-dB ARBW of 31.6%. 26 The key contributions of the proposed antenna are: (1) to excite four CMs simultaneously by a single-feed technique; (2) to manipulate the four CMs for the CP radiation by a novel method; (3) to have a compact size and a low profile of 60 mm  60 mm  1.5 mm; (4) to obtain a dual-band performance of 12.2% (2.3-2.6 GHz) and 53.7% (4.5-7.8 GHz) and to realize a large ARBW (40.7%, 4.9-7.4 GHz); (5) to achieve bi-directional radiation patterns with a broadside peak gain of 4.2 dBic in the usable bandwidth. This article is organized as follows.…”