Error model and calibration of synthetic aperture interferometric radiometer based on visibility function

Traditionally, the system errors of synthetic aperture interferometric radiometers (SAIRs) are analyzed and classified by the causes they are generated, which is easy for understanding but complicated for calibration. This paper presents a new error model based on the visibility function to analyze the system errors of SAIRs. In this model the system errors are classified by their effects on the ideal visibility function, which is simple for calibration. Firstly, the error model based on the visibility function is proposed, in which the errors according to their effects on the ideal visibility function are grouped in: 1) the orientation-independent multiplicative error, 2) the orientation-dependent multiplicative error, and 3) the additive error. Then, the two overall calibration methods respectively using external reference source and external reference scene are proposed. Finally, the preliminary calibration experiment results on the 8mm-band HUST-SAIR prototype show the validity of the error model and the overall calibration methods. The study in this paper provides a means to reduce the complexity of calibration routine of SAIRs and to improve the imaging performance of SAIRs.