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As a transition platform between aircraft and satellite, hypersonic vehicle-borne (HSV) synthetic aperture radar (SAR) could offer many advantages such as strong survival ability, fast response, and wide detection range. However, due to the complex aerodynamic configuration and flight characteristics of the hypersonic platform, the HSV SAR faces new challenges including serious cross-couplings and spatial variations. In order to deal with these issues, a radius/angle algorithm (RAA) is devised, which has a similar processing flow as that of the conventional polar format algorithm (PFA). In the RAA, a novel 2-D interpolation function, similar to that of the PFA which is performed in the Cartesian coordinates, is derived in the curvilinear coordinate system. Due to the high accuracy of the multi-decomposition by using the polar radius and polar angle, the RAA has a much larger depth-of-focus than that of the PFA. Moreover, the RAA approach is insensitive to the height variations for the HSV SAR with curved trajectory flight, whereas the PFA is not because of the out-of-plane projection effect. Simulation results verify the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

In the traditional model of monostatic synthetic aperture radar (SAR), the flying platform should have a uniform linear trajectory. In practice, the flight path of the SAR platform, which is highly nonlinear or curvy caused by 3-D velocity and acceleration, cannot be used in the traditional model. In this paper, a geometrical model of the monostatic SAR with general configurations is graphically illustrated by vector notation. Moreover, the gradient method is utilized to point out the effects of the motion parameters, namely, velocity vector and acceleration vector, on total bandwidth and image resolution. Based on the accurate model, a general frequency-domain algorithm, with the incorporations of pre- and postprocessing, is proposed to focus the raw data. Applicability is studied through theoretical analysis and numerical experiments. All these general analyses can be applied to different realizations of monostatic SAR mode, including spotlight SAR, sliding spotlight SAR, and Terrain Observation by Progressive Scans (TOPS) SAR. [ABSTRACT FROM PUBLISHER]

Synthetic aperture radar (SAR) imaging is usually performed along a straight path. In practice, variations from the ideal caused by maneuvers with acceleration are inevitable. The main problem is the complex signal processing, particularly in the highly squinted spotlight mode. In this paper, acceleration model is analyzed in more details. Impacts are obtained how the acceleration influences the Doppler parameters and space-variant terms, including the SAR resolution and azimuth bandwidth. According to the special signal properties of the acceleration case, an approximation of the range history is made to avoid using the method of series reversion (MSR) to obtain an accurate spectrum. Based on the high-accurate spectrum, a spotlight algorithm with a modified two-step approach is given. Simulation results show the effectiveness of the modified algorithm. [ABSTRACT FROM PUBLISHER]