Radiation Performance of Polarization Selective Carbon Nanotube Sheet Patch Antennas

Carbon nanotube (CNT) sheet patch antennas are explored through simulation, fabrication, and measurement to evaluate the performance of the CNT material as an RF radiator. The thickness of the CNT sheet was found to have a significant impact on the radiation performance of the patch antenna due to the material skin depth, with an ~ 5.5-dB improvement to the realized gain achieved when the CNT sheet thickness was increased from 0.5 μm to 5 μm, likely due to lower surface impedance. The 5 μm-CNT sheet patch antenna exhibited 2.1-dBi total realized gain compared with 5.6-dBi realized gain for baseline copper patch antenna yielding a 3.5-dB reduction attributable to the material substitution. A unique polarization sensitivity behavior was seen by adjusting the alignment of the CNTs within the CNT sheet patch structure. Optimal RF performance was observed when the CNTs within the sheet material were aligned with the E-plane of the patch antenna. When the CNT alignment was orthogonal to that of the E-plane of the patch antenna, the realized gain was reduced by over 8 dB. The input reactance changes from inductive to capacitive due to the geometry and alignment of the CNTs within the patch.