On the Antenna Illumination Effects in Monostatic Reflectivity Determination for Microwave Calibration Targets

In this work, we report the investigation on the methodology for accurately determining the reflectivity of microwave calibration target (MCT), which is a significant parameter for precise radiometer calibration. Specifically, in the common scenario of monostatic measurement, the antenna illumination effects from the feeder T/R antenna were studied, on the reflectivity determination. Since it is almost impossible to get truth value in actual measurement, a numerical evaluation process is established to address this problem, covering the antenna illumination, target scattering, and measurable scattering acquisition, with a reference truth value according to the physical definition of reflectivity. Then, in the numerical results, it can be concluded that the edge diffraction and periodical Floquet interference effects may lead to notable measurement error. For the most convenient measurement setup of monostatic with a nonfocusing feeder antenna, the proper range of application can be concluded, and the corresponding disturbing mechanisms are revealed for practical reference.