This article presents the analysis of the Bragg scattering phenomenon which has been observed in the images of machine-planted rice paddies acquired by the JERS-1 L-band synthetic aperture radar (SAR). The simultaneous measurements of rice plants were made at the SAR data acquisition times. Large differences of 20-25 dB in image intensity between the transplanting and ripening stages are found to be dependent on the planting direction and bunch separation. This selective image enhancement is a result of the Bragg resonance backscatter due to the double-bounce of incident L-band microwave between the flooded water surface and periodically planted bunches of rice plants. Support for the idea of double-bounce scattering is provided by the decomposition analysis of L-band and X-band polarimetric Pi-SAR data; and a simple numerical simulation based on the physical optics model shows fairly good agreement with the JERS-1 SAR data. The results presented in this paper is mainly of academic interest, but a suggestion can be made on the selection of suitable microwave band for monitoring rice fields.

JERS-1 L-band SAR data can be, especially over urban areas affected by ground radar interferences. For most of the applications of the data the interferences should be suppressed. Notch filtering during image correlation process is one of the straightforward ways to do this. However, lower the threshold is, more signals from earth surface is eliminated. In this paper, a probability density function (PDF's) model of the ground radar interference signal is worked out from experimental data, and used for the suppression of interferences and the preservation of backscattered signals. The validity of the model is confirmed against real SAR data, and a general filter threshold--applicable to all JERS-1 SAR data--without any conditions is proposed.

A fully focused Synthetic Aperture Radar (SAR) image can be obtained only if the raw data processing procedure takes into account the space-variance of the SAR system transfer function. This paper presents a nonconventional Fast Fourier Transform (FFT) algorithm which allows an efficient compensation of the space-variant effect. It is specially designed for the SAR data of the Japanese Earth Resources Satellite (JERS-1) but can be extended to different cases.