Capacitively-loaded THz dipole antenna designs with high directivity and high aperture efficiency

Several linearly polarized photoconductive terahertz antenna designs and their performance characteristics are reported. A single capacitively-loaded dipole antenna is introduced first; it has a 12.8 dB directivity, a 11.6 dB realized gain, and a 82% radiation efficiency. By connecting two single capacitively-loaded dipole antennas to form a linear array, higher directivity (14.8 dB), lower sidelobe level (-18 dB) and larger front-to-back-ratio (14 dB) values are achieved. Moreover, by incorporating a meta-film structure as a superstrate of the antenna array, some additional interesting behaviors are achieved.