Emissivity Calculation for a Finite Circular Array of Pyramidal Absorbers Based on Kirchhoff´s Law of Thermal Radiation

Internal calibration source provides reference data for remote sensing system. Realistic calibration source is constructed by finite periodic structure, and hence, the emissivity calculation is different from the infinite periodic array case. In this paper, conventional indirect method based on the scattering field is modified first, so that it can be used to calculate the emissivities of finite homogeneous objects. Subsequently, a new method based on antenna concept is proposed for calculating the differential scattering coefficients and emissivities of the inhomogeneous finite objects. The methods are then applied to finite circular pyramid arrays covered with an absorbing material, and the results are analyzed. Furthermore, the effect of the illuminating scope of incident wave on the emissivity and differential scattering coefficient of circular finite pyramid array is studied.