Research On Availability And Algorithm Of Hypersonic Missile-borne Bistatic Sar

The bistatic missile borne imaging application is the main line of this paper. On the one hand, the characteristic of microwave energy attenuation and phase-frequency characteristics are studied when SAR is used on hypersonic missile. On the other hand, the echo in Doppler-Frequency domain is researched layer upon layer from monostatic SAR to invariant bistatic SAR and then to variant bistatic SAR.1 The transmittance and the phase-frequency characteristics are studies after the microwave go through the plasma outside the hypersonic missile. The meaning of complex number refraction angle is discussed. The impedance method is used to calculate the transmittance of parallel polarization microwave and vertical polarization microwave with different incidence angle and non-uniform plasma. The influence of phase-frequency characteristics to linear frequency modulation signal is studied. The decision basis is given from the energy attenuation and signal processing point of view for SAR applied to hypersonic missile.2 A Chirp Scaling algorithm is put forward for bistatic SAR with parallel flights and the same velocity. Precise range model still exists with this configuration, but it is relative to bistatic angle, which is different from monostatic SAR. The choice of Chirp Scaling factor is discussed. For invariant bistatic SAR, every term in the formula has specific meaning as that of monostatic SAR. Analyzing the meaning of the formula is favorable to the performance of the algorithm.3 The analytical solution in Doppler-Frequency domain for bistatic SAR with parallel flights and different velocities is studied. The Doppler of the echo cannot be used directly with the configuration and the range migration algorithm requires two-dimension interpolations in Doppler-Frequency domain while that of monostatic SAR and invariant bistatic SAR is one-dimension interpolation. Expanding phase with frequency can reduce the interpolation from two dimensions to one but it is still complicated. The analytical solution for variant bistatic SAR is only theoretical, algorithm with high efficiency and approximation is the way to solve practical problems.4 A Chirp-Z algorithm for bistatic forward-looking SAR is put forward with the hypersonic missile moving with acceleration. It is suitable for midcourse guidance and also can be used for terminal guidance.