High-Efficiency Conformal Transmitarray Antenna Based on Miniaturized Tri-Mode Degeneracy Huygens’ Element

This publication proposes an ultrathin tri-mode degeneracy Huygens’ element to overcome the aperture efficiency limitations of current conformal transmitarray antennas (TAs). The proposed element combines the sliding dipole and antisymmetric ring techniques to achieve a degeneracy of one electric resonance mode and two magnetic resonance modes thereby synergistically harnessing the broadband advantage of the multi-resonance modes with the miniaturization advantage of the antisymmetric ring element. The proposed element maintains high transmittance even at an extremely thin thickness of $0.047 \lambda_{0}$, and its small period of $0.42 \times 0.25 \lambda_{0}^{2}$ effectively reduces the phase error caused by aperture bending. Based on the proposed element, we designed a conformal TA prototype featuring a cylindrical aperture. The measurements indicate that the TA prototype demonstrates an aperture efficiency exceeding $60 \%$ and achieves a 3-dB gain bandwidth approaching $\mathbf{1 0 \%}$.