The Study Algorithm Of Airborne Bistatic Synthetic Aperture Radar

Bistatic Synthetic Aperture Radar (Bi-SAR) is a new type of radar system, which uses separated transmitter and receiver flying on different platform. Comparing to monostatic SAR, the Bistatic SAR can configure the geometry of platforms according to the surveillance requirements because of the separation of the transmitter and the receiver. Bistatic SAR has specific advantages, such as the reduced vulnerability in military systems, additional information about the target and characteristics of signal, especially in war condition. All these advantages make it a hot topic in international researches in recent years. Obviously, it has good perspective in both military detection and civil application.Nevertheless, it brings many technical problems such as synchronization of frequency or receiver and transmitter, involved adjustment of transmitter pulse versus receiver gate timing, antenna pointing, and theoretical modeling are not sufficiently solved and motion compensation etc because of the separation of the transmitter and the receiver. Besides, the imaging algorithm of Bistatic SAR is another difficulty. However, it makes the doppler history and two dimensional spectrum of targets because of the range history of a Bistatic target is the sum of two hyperbolic range equations, which give a double square-root term in the range equation, and these are the key point to the algorithm of Bistatic SAR.The azimuth-invariant property is significant for the modern monostatic SAR algorithms that the main processing steps are carried out in the frequency domain. As a result, the efficiency of these algorithms is achieved by taking advantage of block processing. Bistatic SAR, however, Bistatic SAR configurations are much more diverse for the transmitter and receiver. The general case and parallel model have more general characteristic of Bistatic SAR according the geometry situation. Therefore, the study of this paper concentrate both of them. And the study of this dissertation of Airborne Bistatic SAR as follows.The principle of SAR, general case and parallel model according to the geometry situation and echo signals are introduced. The limit of pulse repetition-frequency and the resolution of the Bistatic SAR are analyzed. Pulse compression (matched filter) which is the key technologies is investigated.Based on the introduction of the general case and parallel model, the two dimensional spectrum of point target is given by introduced and analyzed the method of MSR and LBF, then this paper approach the two dimensional spectrum using Taylor series expansion the history of range.In succession, Range Doppler algorithm using the Taylor series expansion and BP(Back-Projection) algorithm of Bistatic SAR is discussed. The efficiency and applicability of the two algorithms are verified by imaging simulation experiment of point targets. The simulation results demonstrate the correctness of the two algorithms. The quality of images acquired by the BP algorithm is much better than RD algorithm. The RD algorithm work better on the classical two order model and has low computation, but not better on the general case. Furthermore, the BP algorithm is adapted for general case but needs massive computation. And for the disadvantages of RD algorithm and BP algorithm, some advances prospect:reduction the computation of BP algorithm and expansion the applicability BP algorithm are the main problems;and decreasing the noise and increasing the resolution of the Bistaitc SAR is the key point.