Abstract

Three-dimensional (3D) imaging technology based on antenna array is one of the most important 3D synthetic aperture radar (SAR) high resolution imaging modes. In this paper, a novel 3D imaging method is proposed for airborne down-looking sparse array SAR based on the imaging geometry and the characteristic of echo signal. The key point of the proposed algorithm is the introduction of a special squint model in cross track processing to obtain accurate focusing. In this special squint model, point targets with different cross track positions have different squint angles at the same range resolution cell, which is different from the conventional squint SAR. However, after theory analysis and formulation deduction, the imaging procedure can be processed with the uniform reference function, and the phase compensation factors and algorithm realization procedure are demonstrated in detail. As the method requires only Fourier transform and multiplications and thus avoids interpolations, it is computationally efficient. Simulations with point scatterers are used to validate the method.

Highlights

  • Traditional synthetic aperture radar (SAR) utilizes pulse compression and synthetic aperture technique to form high resolution two-dimensional (2D) images of the observed area with weather independence and all-day operation capabilities [1, 2]

  • The main topic of this paper is to introduce an accurate and efficient 3D imaging algorithm for down-looking sparse array SAR

  • The phase compensation factors and algorithm realization procedure are demonstrated in detail

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Summary

Introduction

Traditional synthetic aperture radar (SAR) utilizes pulse compression and synthetic aperture technique to form high resolution two-dimensional (2D) images of the observed area with weather independence and all-day operation capabilities [1, 2]. Multibaseline SAR tomography is an advanced 3D SAR imaging mode, which exploits the multibaseline nature to allow distinguishing multiple scatterers at different heights within the same azimuth-range resolution cell It allows measuring the scattering distribution in the 3D space. Some methods based on compressive sensing (CS) were applied to array SAR imaging [14, 15], providing an improved resolution in cross track direction. These methods suffered from severe computation loads and were hard to realize real-time imaging.

Geometrical Model of Airborne Down-Looking Sparse Array SAR
Simulation Results
Conclusions
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