Theoretical And Methodology Study For Improving Spatial Resolution Of Passive Microwave Radiometer

Passive microwave remote sensor has lower spatial resolution because of the restriction of the physical size of antenna beam. Besides, conventional spatial scanned imaging radiometers acquires radiometric signal point and point. It is a time-consuming process to when get the whole image. This kind of scanning mode is the main constraint for passive microwave imaging application. Synthetic aperture microwave radiometer is a novel passive remote sensing imaging technique which has many advantages, such as higher spatial resolution and high imaging speed.Conventional scanning imaging model in spatial-domain and synthetic aperture imaging model in complex spatial frequency-domain are compared and analyzed. First order interferometric technique obtains the spatial domain image by inverse Fourier transformation of the complete interfeometric sampling points. The phase shifting interference technology is introduced to eliminate the alias phenomena and obtains the entire complex spatial frequency information of the extended target sources, which we can derive the target brightness temperature image through the image retrieval algorithm. It improves the spatial resolution and at the same time also improves the imaging processing speed.In order to advance this technology forward, the thesis studies the second-order interferometric method and imaging process. This new technique increase the resolution of the first order interferometric method by a factor of two. On the practical side, an one-dimension thinned array based on second-order interference theory is established and the simulation results validate the new theory. The performance of new theory such as FOV, sensitivity and spatial resolution is analyzed in detail in the paper.