Theoretical investigations on the influence of photonic crystal shapes on the performance of graphene-based terahertz photoconductive bowtie dipole antenna

Graphene-based photoconductive bowtie dipole antenna for terahertz radiation is investigated under different geometrical shapes of photonic crystal employed in the semi-conductor substrate. The antenna is designed using graphene radiator and Gallium Arsenide substrate to operate at 1.4 THz, 1.9 THz and 2.1 THz frequencies. Cylindrical, square, triangular and hexagonal shaped photonic crystal substrates are investigated. The analysis is carried out for various antenna parameters such as reflection coefficient, VSWR, directivity and radiation effi-ciency. Further, polarisation aspects such as axial ratio and cross-polarisation level are also discussed. Opto-electronic simulation is performed to determine the influence of photonic crystal shapes on the emission char-acteristics of photoconductive antenna. Simulation results indicate that hexagonal-shaped photonic crystals provide directivity of 15 dBi, axial ratio of 29 dB, efficiency of 98% and emission spectrum bandwidth of 220 GHz, which ascertain its suitability for terahertz photoconductive antenna.