Photoconductive THz Antenna Designs With High Radiation Efficiency, High Directivity, and High Aperture Efficiency

Several linear polarized photoconductive terahertz antennas are reported and compared. A bowtie-shaped antenna, which is a variation on the standard photoconductive dipole antenna, is presented. It has satisfactory terahertz (THz) radiation performance characteristics. This bowtie-shaped antenna is combined with a silicon-based lens and with an artificial magnetic conductor (AMC) to enhance its directivity properties. These antennas provide the baseline designs in our study. A capacitively loaded dipole antenna is introduced, which naturally leads to an array implementation. The simulation results show that the peak directivity of a two-element array can be increased by 2.0 dB. The directivity and front-to-back ratio of the capacitively loaded dipole array are further enhanced by introducing a meta-film superstrate. Superdirective and high-efficiency performance characteristics are demonstrated. A THz grid antenna and its generalization to a grid antenna array are also developed. Comparisons demonstrate that these planar designs significantly outperform the lens-based reference case.