The Progress in Optimization of Small-scale Calibration Targets at THz Frequencies

In this paper, the small-sized blackbody (calibration targets) is optimized for better wide-band low-reflectivity performance. The pyramidal unit is optimized with a curved kernel, also with the nonuniform coating layer. The reflectivity performance of the coated pyramids is investigated from 50GHz to 700GHz, based on the full-wave finite difference time domain (FDTD) computations. Comparing to the original uniformly coated pyramid, the optimized design achieves better absorption in the low-frequency region, and eliminates Fabre-Perot(F-P) resonance which leads to frequency ripples at high frequencies. In addition, different structural parameters of the pyramidal unit are investigated, such as periods and height/period ratios. This work provides a reference for the further optimization of the calibration target in the future.