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A new two-dimensional (2D) holographic microwave imaging technique is proposed to reconstruct the 2D image of a target. It is based on the Fourier analysis of the data recorded by two antennas scanning together two separate rectangular parallel apertures on both sides of a target. The complex backscattered signals of the two antennas are first processed to localize the target in the range direction. Then, the 2D image of the target is reconstructed. No assumptions are made about the incident fields, which can be derived by either simulation or measurement. Both the back-scattered and forward-scattered signals can be used to reconstruct the image of the target. This makes the proposed technique applicable with near-field measurements. To evaluate the proposed technique, the range localization and the 2D image reconstruction of a predetermined simulated target are examined. Associated resolution limits, sampling constraints and the impact of noise are also discussed.

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[1] The detection performance of high frequency surface wave radar (HFSWR) and high frequency over-the-horizon radar (OTHR) systems is heavily influenced by the presence of radar clutter. In HFSWR systems, the clutter has its origins in vertical-incidence ionospheric reflections, whereas in OTHR systems, the origin is Bragg backscatter from plasma structures in the auroral zone. This paper models the spreading of the radar clutter signal in the Doppler and angle-of-arrival domains that arises from forward-scattering effects as the radar pulse propagates through regions of ionospheric plasma irregularities. The models use a geometric optics approach to determine the power spectrum of the radar signal phase. This power spectrum is then used to simulate three-dimensional space-time-range radar data cubes. The accuracy of the models is tested by comparing the simulated data to measured data cubes. As an application, the data are then used to evaluate the performance of the newly developed fast fully adaptive (FFA) space-time adaptive processing (STAP) scheme to improve the extraction of target echoes from a clutter background.Citation: Ravan, M., R. J. Riddolls, and R. S. Adve (2012), Ionospheric and auroral clutter models for HF surface wave and over-the-horizon radar systems, Radio Sci., 47, RS3010,