Design and Fabrication of WR-28 Blackbody Target

The standard microwave blackbody is widely used as a reference for radiometer calibration techniques. The absorbing material and the shape design are the key aspects in the fabrication of the commonly used pyramidal array blackbody. This study investigates the permittivity and permeability of absorbing materials with different proportions within the frequency range of 26.5GHz to 40GHz using the transmission/reflection method. The dimensions of the pyramidal cone are optimized through simulation. A pyramidal array blackbody target with a period of 30 mm, an aspect ratio of 4, and a layer thickness of 1.5 mm is fabricated. The blackbody target is measured by the free space sliding-load method. The results demonstrate that the reflection coefficients of the target are less than -30 dB in the full band.