One-dimensional Synthetic Aperture Microwave Radiometer Set The Standard Technology Research And Image Simulator Developed

Synthetic aperture microwave radiometer represents a new technology being developed for passive microwave remote sensing. Aperture synthesis uses interferometry technique to improve the limitations set by antenna physical aperture while working at lower frequency.Phase and amplitude calibration of the visibility samples must be carried out to compensate for system bias before measurement. This bias mainly come from the un-uniform characteristics of the system and the couplings between the receiving channels. If we use Fourier transformation to retrieve the image, the errors introduced by this bias will not be represented. To take into account this problem, a numerical image retrieving method is considered using an intermediate transformation matrix. This matrix takes into account all the couplings , un-uniformed amplitude and phase between the channels. This matrix is called the gain matrix or simply G -matrix.However, to measure the G -matrix is not an easy job. One has to set up a point source in the far field and rotate the system in the fan beam direction. The difficulty is mainly due to the incomplete test environment.In this dissertation, a measurement set-up called image simulator is presented. The set-up is a circuit network composed of a number of highly accurate microwave IQ vector modulators and a noise generator. It simulates the incoming waves to the thinned antenna array corresponding to any image scene to be measured. During measurement, the simulator's outputs are connected to the RF inputs of each channel. The incoming wave is then simulated by computer program to drive each of the digital IQ vector modulator. The design and test of the image simulator is presented and followed with test results of G -matrix.