Circularly Polarized Antenna With Polarization-Compliable PRS Unit Cells for Gain Enhancement and Sidelobe Suppression
Journal
IEEE Access
Journal Volume
14
Start Page
52467
End Page
52478
ISSN
2169-3536
Date Issued
2026-04-03
Author(s)
Phaebua, Kittisak
Chalermwisutkul, Suramate
Lertwiriyaprapa, Titipong
Torrungrueng, Danai
Abstract
This paper presents a compact circularly polarized (CP) antenna that achieves high gain and low sidelobe levels (SLL) using a single-layer polarization-compliable partially reflective surface (PRS). Each PRS unit cell combines overlapping cross- and rectangular-slot elements to provide balanced reflection responses for vertical and horizontal polarizations while suppressing cross-polarization. By jointly optimizing the reflection magnitude and phase of both polarizations, the proposed PRS achieves uniform aperture-field distribution that enhances gain and preserves edge tapering for SLL suppression. In addition, alternative analysis framework, in which the PRS layer modeled as a Bi-Characteristic-Impedance Transmission Line (BCITL), is proposed. By retrieving the BCITL parameters ((Z+0, Z?0 , γ) from Floquet-mode S-parameters of the PRS unit cell, the method reveals the intrinsic propagation constant of the PRS layer and clarifies the relation between the PRS reflection coefficient and the BCITL parameters (Z+0, Z- 0, γ). This dual viewpoint (full-wave and BCITL) provides deeper physical insight into how the PRS height, co- and cross- polarized reflection coefficients, and edge taper collectively influence the gain and SLL trade-off. The retrieved cross-polarized propagation constants exhibit strong attenuation, confirming that cross-polarized modes are effectively suppressed thus maintaining the purity of the CP main beam and low SLL. A corner-trimmed square patch antenna operating at 10 GHz is used to validate the concept, achieving a simulated gain increase from 5.8 to 24 dBic with SLLs below -22 dB, axial ratio (AR) <2.5dB. The proposed PRS features an aperture of 6.27λ ×6.27λ and a compact thickness of only 0.5λ (λ denotes the free space wavelength), achieving a simulated aperture efficiency of 60%. Measurement results confirm the simulations and validate the effectiveness of the proposed design, validating both the design concept and the BCITL-based interpretation.
Subjects
Aperture efficiency (AE)
bi-characteristic-impedance transmission line (BCITL)
circular polarization (CP)
gain enhancement
partially reflective surface (PRS)
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Type
journal article