Design of Impedance Copuplers for Graphene Nanoantenna in the Thz Band

The wireless communications of future generations will require nanoantennas capable of working in the band of Terahertz, however, the miniaturization causes difficulties in conductivity, high propagation losses, and degradation in radiation efficiency. In addition, to obtain the maximum power transfer in a nanoscale wireless communication system, impedance couplers are required. Therefore, a graphene-based patch-typenanoantenna was modeled on two dielectric substrates, silicon, and silicon dioxide, in which a BIAS voltage between 0.83 and 29.9 V was applied. For the coupling of the patch with the power port, direct contact methods were used, such as a 50 Ω microstrip line, inserts in the patch, and the quarter-wave transformer. The best results obtained from the performance comparison were with the quarter wave transformer with a return loss of -33.54 dB, gain 5.6 dBi, directivity 6.05 dBi, VSWR of 1.15, a bandwidth of 350 GHz,efficiency of 92%, HPBW 99.2°, F/B 12.8 dB for a resonance frequency of 2.6 THz and in the case of 4.2 THz a return loss of -35.24 dB, gain 4.9 dBi, directivity 5.6 dBi, VSWR of 1.13, bandwidth 187 GHz with 90% efficiency, HPBW 106.5°, F/B 12.2 dB. So, the quarter wave transformer is optimal for matching impedances, achieving low propagation losses, and complying with the optimal operating parameters.