Large-Frequency-Ratio X/Ka Dual-Band Transmitarray Antenna Exploiting Effective Operating Size Differences of Huygens’ Elements

Abstract

A dual-band orthogonally polarized transmitarray antenna (TA) aperture design scheme featuring a large frequency ratio (FR) is presented. The proposed aperture is implemented by employing two thin Huygens’ elements: glide bilayer-dipole-pair (GBDP) and parallel bilayer-dipole-pairs (PBDP) elements, which exhibit widely varying electrical sizes. Initially, we investigate the effective operating sizes of these two types of Huygens’ elements and observe significant disparities in their operating sizes due to variations in their magneto-electric degeneracy mechanisms. Subsequently, by exploiting the disparity in elements’ effective operating sizes, we arrange the two elements orthogonally within a single aperture, thereby achieving dual-band functionality with a significantly large FR. Furthermore, we design an X/Ka dual-band orthogonal linearly polarized TA prototype to verify the advantages offered by our proposed strategy. The GBDP element is employed to modulate the x-polarized waves in Ka band, with an electrical size of 0.6${\bm{\lambda }}_h \times $ 0.6${\bm{\lambda }}_h \times $ 0.18${\bm{\lambda }}_h$. Concurrently, the PBDP element is utilized to modulate the y-polarized waves in X band with an electrical size of 0.4${\bm{\lambda }}_l \times $ 0.4${\bm{\lambda }}_l \times $ 0.06${\bm{\lambda }}_l$. Here, ${{{\bm{\lambda }}}_h}$ and ${{{\bm{\lambda }}}_l}$ denote the wavelengths corresponding to 30 and 10 GHz, respectively. Measurements indicate that the FR of the dual-band prototype reaches 3, with a 3 dB/1 dB gain bandwidth of 12.6%/4% in X band and 8.1%/4.7% in Ka band. The peak gain of the prototype is 22.56/29.73 dBi in X/Ka bands, respectively.