Performance comparison of a planar substrate-integrated Fabry-Perot cavity antenna with different unit cells at terahertz frequency

In this paper, we investigate and compare the radiation characteristics of a planar substrate-integrated Fabry-Perot cavity antenna designed with different unit-cell geometries. The antenna consists of a frequency selective surface (FSS) and a planar feeding structure, which are both lithographically patterned on a high-permittivity substrate. The planar feeding structure is an open-ended leaky-wave slit with a large ground plane, while the FSS is a 7 × 7 array of unit cells. Antennas with FSSs using different unit-cell geometries were studied at a frequency of around 0.315 THz. The numerical results showed that the FSS with square-patch unit cells achieved the best maximum gain of 14.3 dBi, while the FSS with circular-patch unit cells produced the best 3-dB gain bandwidth of 3%.