Near-Field Antenna Reception of Thermal Radiation from Calibration Targets

The calibration process is vital for the quantitative microwave radiometer observation. In the calibration link an interesting near-field propagation problem exists, which is the antenna reception of thermal radiation from the calibration target. In recent researches, the target optimization aimed at better thermal radiation performance, and equivalent antenna reception modeling are separately advanced. In this work, the authors report their progress in modeling the antenna reception scenario, which includes both the targets and antenna structures. Specifically, the incoherent thermal radiation from the coating layer of calibration targets is modeled as random noise-like signal in time domain, then the antenna reception can be calculated based on the time-averaged Poynting vector though the waveguide port. 2-D finite difference time domain method is used to simulate the thermal radiation and reception in a full-way manner. The numerical case of coated plate radiation validates the modeling method. Then the variation of antenna received power versus relative positions of antenna and targets are observed in the results, showing the complex scenario of close range antenna reception of thermal radiation in the calibration process.