W-Band Circularly Polarized Antenna Array With Dual Split Rings and Hexagonal Lattices for Satellite Communication

Abstract

This paper proposes a W-band circularly polarized (CP) antenna array utilizing dual split rings and hexagonal lattices for satellite communication (SatCom). The dual split rings are sequentially stacked on top of a multilayer printed circuit board (PCB) and are aperture-coupled by a feeding ring. The magnitude and phase of the induced currents in the dual rings are independently controlled by adjusting the line width and rotation angle to achieve optimal AR performance, while the radius and split gap of the rings determine the resonant frequency. This enables greater flexibility in PCB-based W-band CP antenna design against manufacturing constraints. The feeding ring is excited by a center via post within a hexagonal lattice. The rotational symmetry of this feeding structure facilitates symmetric beam patterns, required for two-dimensional beam steering in SatCom. In addition, via fence surrounding the center via post mitigates mutual coupling caused by surface waves. The effectiveness of the proposed design approach is demonstrated by a full-wave numerical simulation and validated through fabrication and measurement. The fabricated 4x8 antenna array exhibits VSWR <2 over 15 GHz ( 85-100 GHz), a 3-dB axial ratio bandwidth of 2.8 GHz ( 89.7-92.5 GHz), and a peak right-hand circular polarization gain of 15.7 dBic at 92 GHz. The fabricated array shows beam steering capabilities of +/- 60 degrees with scan loss up to 4.5 dB at 92 GHz.