Terahertz High-Gain Leaky-Wave Antenna Utilizing Valley Topological Photonic Crystals with Line Defects

Abstract By utilizing topological edge states in the fast-wave region and eliminating back reflections, topological photonic crystal (TPC)-based antennas emerge as a promising research direction. In this paper, a leaky-wave topological antenna (TA) is designed using a valley TPC-based topological waveguide (TW) with line defects. We theoretically calculate the antenna's radiation direction and propagation constant, elucidating its radiation mechanism, and verified the results through simulations, which demonstrate excellent agreement with the theoretical predictions. Operating between 0.382 and 0.426 THz, the TA exhibits frequency-scanning capabilities and robustness against fabrication defects. The transverse electric and magnetic (TEM) horn antenna, compatible with the TW, was utilized to refine the beam shape from a fan-shaped beam to a pencil beam, enhancing its suitability for practical application scenarios. The impact of TEM horn antennas with aperture angles of 30°, 40°, and 50° on the performance and radiation patterns of the TA is evaluated. The simulation results indicate that the designed TA demonstrates excellent performance, achieving a maximum realized gain of 21.7 dBi, an aperture efficiency of 63.7%, and a total efficiency exceeding 80%, with a peak value of 95%. This work simulates a leaky-wave valley TA design operating near the 0.410 THz atmospheric window, advancing the theoretical study of TPC radiation, accelerating their engineering applications, and highlighting their significant potential for practical use.