Inverse synthetic aperture radar (ISAR) imaging of a maneuvering target is a challenging task in the field of radar signal processing. The azimuth echo can be characterized as a multi-component polynomial phase signal (PPS) after the translational compensation, and the high quality ISAR images can be obtained by the parameters estimation of it combined with the Range-Instantaneous-Doppler (RID) technique. In this paper, a novel parameters estimation algorithm of the multi-component PPS with order three (cubic phase signal-CPS) based on the modified discrete polynomial-phase transform (MDPT) is proposed, and the corresponding new ISAR imaging algorithm is presented consequently. This algorithm is efficient and accurate to generate a focused ISAR image, and the results of real data demonstrate the effectiveness of it.

For inverse synthetic aperture radar (ISAR) imaging of maneuvering targets, the Doppler frequency induced by an arbitrary scatterer on the target is time-varying, and hence, the traditional range-Doppler (RD) algorithm is not appropriate for obtaining focusing ISAR images. In such a scenario, a novel ISAR technique, called the range instantaneous Doppler derivative (RIDD) algorithm, has been recently proposed, and two different kinds of well-focused ISAR images, named range-Doppler centroid (RDC) frequency image and range-Doppler frequency rate (RDR) image, can be obtained. In order to improve the accuracy of the target classification and recognition, the scaling approach for the RIDD algorithm must be taken into consideration. In this article, the point spread function (PSF) representations and cross-range scaling factors of the RDC image and the RDR image obtained by the RIDD algorithm are demonstrated analytically. On the basis of the PSFs and cross-range scaling factors, a novel imaging and scaling approach for the RIDD algorithm in the presence of a low SNR environment based on smoothed integrated high-resolution time–frequency-rate representation (SIHR) combined with coherent integrated smoothed generalized cubic phase function (CISCF) is proposed. As the proposed algorithm has high estimation accuracy and good antinoise capability, precise parameter estimation of the received signal can be achieved. Hence, high-quality scaled RDC and RDR images of the target can be reconstructed by the proposed approach. Experimental results of simulated data and real measured data verify the correctness of the PSF representations and demonstrate the effectiveness of the imaging and scaling approach proposed in this article.

Radiation-induced single event transients (SETs) are expected to evolve to single event multiple transients (SEMTs) due to the downscaling of transistor feature size, which also increases the difficulty of the vulnerability estimation for large scale digital integrated circuits (ICs). In this paper, a novel layout-based soft error vulnerability estimation approach which is termed LBSEVEA is proposed to evaluate the impact of heavy ions on the vulnerability of combinational circuits. Moreover, the physical process of interaction between particles and devices, especially nuclear reaction and scattering process are included in the LBSEVEA. In addition, ambipolar diffusion and bipolar amplification effect, which induce additional charge collection of the adjacent transistors and the hitting transistor, are also considered. A new method calculating the collected charge induced by the bipolar amplification effect is presented. By introducing the layout information of the target circuits into the identification of the adjacent cells, SEMTs effect can be considered in the vulnerability estimation. A fast SPICE simulation tool is adopted to conduct the fault injected netlist simulations, which can make a favorable compromise between the consumption of computer resources and simulation precision. Furthermore, induced soft error numbers, distribution of charge collected by the hitting nodes and the adjacent nodes, and SET pulse width distributions are presented. Besides, heatmaps of induced pulse widths for the layout of two benchmark circuits are provided. Finally, the constraints, the flexibility and the scalability of the LBSEVEA are discussed. The ability to estimate the impact of process variations on the vulnerability is also presented. Compared with simulation and experimental results, the LBSEVEA can fairly estimate the vulnerability of the combinational circuit.

Metasurfaces, as two-dimensional (2-D) metamaterials, show great potentials in electromagnetic wave manipulation. Here, an angular nondispersive transmission-type Huygens’ meta-atom, made up of an I-shaped metal patch and a square split ring, is proposed for wide incidence angle holographic metasurfaces. Nine varieties of the Huygens’ meta-atom with high transmission amplitude (higher than 0.9) and stable transmission phase (vary less than 10°) under transverse magnetic wave illumination from 0° to 60° are selected. To verify the performance of the meta-atoms proposed, two holographic metasurfaces are simulated and fabricated to reconstitute identical holographic images under normal and oblique linearly polarized wave illuminations, respectively. The experimental demonstrations show imaging efficiencies higher than 48.28% with signal-to-noise ratio as high as 22.57. Our designs provide a solution for angular nondispersive metasurface designs, which suggest great practical applications in beamforming, and information storage systems.