Tuning Bolometric Parameters of Sierpinski Fractal Antenna-Coupled Uncracked/Cracked SWCNT Films by Thermoelectric Characterization at UHF Frequencies

Abstract

In this work, the bolometric parameters of Sierpinski fractal antenna-coupled SWCNT semi-metallic films are obtained by thermoelectric characterization, this in order to find out the performance as bolometer. The method was based on an experimental setup considering a line-of-sight wireless link between two identical planar fractal antennas, infrared thermography, and electrical resistance measurements. The experimental setup considered the antennas resonant frequencies. Both the transmitting and receiving antenna were third-iteration Sierpinski fractal dipoles designed to work at UHF frequencies. Films made either of cracked or uncracked SWCNT films were each separately coupled to the receiving fractal antenna. Measurements showed that the receiving antenna that was impinged with radiation at UHF frequencies coming from the transmitting antenna, experienced as it was expected an induction of electric current, the induced current flowed through the film producing a temperature change, which in turn caused changes in the radiated heat of the film, as well as changes in the electrical resistance known as Temperature Coefficient of Resistance TCR. The maximum value of TCR for uncracked SWCNT films was −3.6%K−1, higher than the one observed for cracked SWCNT films which exhibited a maximum value of −1.46%K−1. Measurements for conversion of incident radiation to electrical signals known as the Voltage Responsivity ℜv, exhibited values of 9.4 mV/W and 1.4 mV/W for uncracked SWCNT films and cracked SWCNT films, respectively.