No abstract

Abstract-The full MIMO radar and the partial MIMO one are introduced. The performance analysis of beamforming for MIMO (Multiple-input Multiple-output) radar and comparisons with the phased-array radar are given. The expressions of beamwidth, gain loss and detection range for MIMO radar are derived. Theoretical analysis and simulations show that the beam of the full MIMO utilizing all virtual array elements is identical to the two-way beam of the phasedarray radar, and that the beam of the partial MIMO selecting elements with different phase centers (phase shifts) is narrower, but has a gain loss. Additionally, the partial MIMO can avoid aliasing in space when the transmitting antennas are spaced at greater than half-wavelength spacing. As scanning radar, the partial MIMO radar has smaller detection range than the phased-array radar, and the full MIMO radar has the same range as the phased-array radar.

No abstract

Abstract-When airborne forward looking planar antenna is used to detect ground moving target, targets may be masked by strong clutter due to high sidelobes of the antenna pattern. In this paper, transmitting pattern is synthesized via convex optimization in order to suppress clutter from ground. Transmitting pattern has a low sidelobe illuminating short ranges and a high sidelobe focused into sky and remote ranges, which results in a relative small beamwidth in the elevation plane. In the azimuthal plane, transmitting pattern can form some notches in some fixed directions where strong clutter and interference exist. With insufficient training data due to a dispersion of clutter spectrum along range, adaptive receiving pattern with low sidelobes can be obtained by convex optimization when detecting remote targets.Simulation results show that transmitting and receiving patterns can effectively be designed via convex optimization for airborne forward looking radar.

The results of the linear range cell migration (RCM) correction and inherent range-dependent squint angle in the case of high-resolution highly squinted synthetic aperture radar (SAR) imaging produce two-dimensional (2-D) spatial-variant RCMs and azimuth-dependent Doppler parameters (i.e., highly varying Doppler centroid and frequency modulation rates), which make highly squinted SAR imaging difficult. However, the most existing algorithms failed to consider these problems. To obtain highquality SAR image, in this study, both the 2-D spatial-variant RCMs and the azimuth-dependent Doppler parameters are stud- ied. First, a reference range linear RCM correction (RCMC) is used to remove the most of the linear RCM components and to mitigate the range-azimuth coupling of the 2-D spectrum. And then, in the azimuth time dimension, a new perturbation function is designed in the extended nonlinear chirp scaling (CS) (ENLCS) algorithm to overcome the azimuth-dependent RCM and to equalize Doppler parameters. To remove both the inherent range-dependent RCM and the linear RCM caused by the range-dependent squint angle, a modified CS (MCS) algorithm with a new scaling function isproposed, and for the residual RCMs, a bulk RCMC and second range compression (SRC) are utilized to compensate them. With the proposed ENLCS and MCS operation, the 2-D spatial-variant RCMC and the azimuth-dependent Doppler equalization are, thus, achieved. The experimental results with simulated data in the case of the high-resolution highly squinted SAR demonstrate the superior performance of the proposed algorithm.Index Terms-Azimuth-dependent Doppler Equalization, extended nonlinear chirp scaling (ENLCS) algorithm, modified CS (MCS) algorithm, synthetic aperture radar (SAR),