A Wavelet Based Scattering Data Interpolation in Synthetic Aperture Microwave Radiomter

Abstract

Soil moisture and ocean salinity are two important parameters for water cycle and climate change studies. The best way to measure these two parameters is to use microwave radiometer at low frequency band, such as P or L band. However, at these frequencies, the physical size of the antenna is very big in order to reach a modest spatial resolution. To scan such kind of large antenna is also difficult. Further more, if the antenna beam become very narrow, the integration time of each resolution cell will become small which will lead to poor measurement sensitivity.;To overcome all difficulties mentioned above, the synthetic aperture microwave radiometer technology is proposed. This technology uses both thinned array antenna and electrical scan. Therefore not only the large/heavy antenna aperture problem is solved, but also the integration time will not be related to the spatial resolution any more. It is therefore a very promising technology for low frequency band microwave radiometers and can be implemented for soil moisture and ocean salinity applications.;The basic concept of synthetic aperture radiometer is to measure spatial frequency of the scene instead of the image itself. The output of the spatial frequency is usually called the visibillity function (VF). While all the spatial frequency outputs or VF are measured, corresponding to all baselines with different length and orientation, the image of the scene is a mathematical transformation of the VF. ;This paper put forward an interpolation method based on wavelet transform, whose role is to give a modification to the Fourier image reconstruction arithmetic of 2|D microwave synthetic aperture radiometer.