LAUSR

In this work, the authors investigate the calibration target design for sub-millimeter wave radiometer applications, with specific focus on further improving the brightness temperature radiation accuracy during the miniaturization. The investigation is based on latest design of curved inner kernel for the frequently utilized periodic coated pyramidal target. The numerical study combines the electromagnetic and thermal analysis; then, the overall brightness temperature performance can be investigated. Within the typical frequency range of 50–500 GHz, results show that the target miniaturization can lead to clearly improved brightness temperature radiation accuracy, however, only in case the correct design strategy is applied. The key is that the coating thickness should be proportionally reduced during the miniaturization, so that the temperature gradient at the tips can be notably relieved. On the contrary, keeping the coating thickness unchanged will result in a notable degradation of brightness temperature accuracy. The investigation also includes the important aspect of coating material, for comprehensively referencing for sub-millimeter wave radiometer applications.