Reduction of Surface Reflection on Dielectric Lens Antenna by Matching Periodic Square-Pillars in 300-GHz Band

This study proposes a dielectric lens antenna that implements an impedance matching layer comprising square-pillar periodic structures on the lens surface to reduce the surface reflection formed in the lens from a high-permittivity dielectric material. To ease the fabrication process, the matching structures (MS) implemented on the lens surface are made of the same dielectric material as the dielectric lens through microfabrication structure. The dimensions of the square-pillar periodic MS unit cell are optimized for its period, space occupancy ratio, and height using periodic boundary simulation, considering the plane wave incident. Electromagnetic simulations and experiments to evaluate the effectiveness of the optimized square-pillar periodic MS were conducted. Implementing the square-pillar periodic MS to a lens composed of modified-polyphenylene ether (modified-PPE) with a relative permittivity of 5.34 assists in reducing the surface reflection inside the lens compared with the lens without anti-reflection and improves the peak gain by approximately 2 dB from 250 to 290 GHz.