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Wang W.,Northwestern Polytechnical University | Wan G.,Northwestern Polytechnical University | Wang L.,Northwestern Polytechnical University | Shen J.,Northwestern Polytechnical University | Shen J.,Aviation Key Laboratory of Science and Technology on AISSS
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2015

A fast and effective method of radome boresight error (BSE) optimization by adjusting the phase compensation value of phased array elements is proposed. Particle swarm optimization (PSO) is adopted, applying to the case of continuously adjustable phase or digital discrete phase. With the phase offset optimization technology in the optimization encoding, the quantization error of low phase shifters is effectively reduced. The speed updating formula of BSE optimization is improved combined with prior information, and the convergence speed is improved. Pre-computed matrices on behalf of field source relationship are established to reduce the computation of solving the fitness function and save the numerical calculation time. The validity and effectiveness of the presented approach are confirmed by optimal design of a 16 elements array-radome system with 4-bits phase shifters. Copyright © 2015 by Editorial Department of Chinese Journal of Radio Science Source

Zhao G.,Xidian University | Wang Q.,Xidian University | Shen F.,Xidian University | Li X.,Aviation Key Laboratory of Science and Technology on AISSS | Shi G.,Xidian University
IET Radar, Sonar and Navigation | Year: 2013

Canonical multi-input-multi-output (MIMO) imaging methods suffer from limited resolution, poor robustness against noise and high computational complexity, especially when the array aperture is limited (affecting angular resolution) and the number of snapshots is limited (affecting Doppler resolution). In this study, the authors discuss a new range-angle-Doppler monostatic MIMO imaging method through adaptive estimation of the generalised Cauchy prior distribution (GCD). The superiority of GCD-based model over existing ℓp-norm-based model (which actually assumes the prior as general Gaussian distribution) is theoretically verified through the issue of signal compressibility. The authors adapt a reweighted ℓ2-norm iterative algorithm to solve the model. In our model the authors do not pre-define the scaling factor of the prior distribution and, during the iteration, the authors use a novel 'quantile-of-OS' method to adaptively estimate the scaling parameter of the prior distribution, enhancing the robustness of the method. Simulation results verify the image quality and speed advantages of the proposed method. © The Institution of Engineering and Technology 2013. Source

Huang T.,Beijing Institute of Technology | Huang T.,Aviation Key Laboratory of Science and Technology on AISSS | Zhao T.,Beijing Institute of Technology | Zhao T.,Aviation Key Laboratory of Science and Technology on AISSS
IEEE Signal Processing Letters | Year: 2015

This letter considers waveform design of orthogonal frequency division multiplexing (OFDM) signal for radar applications, and aims at mitigating the envelope fluctuation in OFDM. A novel method is proposed to reduce the peak-to-mean envelope power ratio (PMEPR), which is commonly used to evaluate the fluctuation. The proposed method is based on the tone reservation approach, in which some bits or subcarriers of OFDM are allocated for decreasing PMEPR. We introduce the coefficient of variation of envelopes (CVE) as the cost function for waveform optimization, and develop an iterative least squares algorithm. Minimizing CVE leads to distinct PMEPR reduction, and it is guaranteed that the cost function monotonically decreases by applying the iterative algorithm. Simulations demonstrate that the envelope is significantly smoothed by the proposed method. © 2015 IEEE. Source

Zhao T.,Beijing Institute of Technology | Zhao T.,Aviation Key Laboratory of Science and Technology on AISSS | Huang T.,Beijing Institute of Technology | Huang T.,Aviation Key Laboratory of Science and Technology on AISSS
2015 IEEE Global Conference on Signal and Information Processing, GlobalSIP 2015 | Year: 2015

The Cramer-Rao Lower Bounds (CRLBs) of the joint time delay and Doppler stretch estimation for an extended target is derived in this paper. The results indicate that the CRLB of the Doppler stretch is inversely proportional to the effective time-bandwidth product of the transmitted signal. The estimator using wideband ambiguity function (WBAF) is evaluated for the extended target case through numerical experiments. Our results indicate that the WBAF estimator, which is derived under the single point scatterer assumption, is not appropriate to the parameter estimation for an extended target. © 2015 IEEE. Source

Yan X.,Wuxi Institute of Technology | Yan X.,Aviation Key Laboratory of Science and Technology on AISSS | Yuan Y.,Wuxi Institute of Technology | Yuan Y.,Aviation Key Laboratory of Science and Technology on AISSS
Lecture Notes in Electrical Engineering | Year: 2016

A design of fed-divider is provided for ridge waveguide antenna array. The equivalent model of fed-slot is deduced and the fed-slots are calculated accurately at first. Based on the analytical model, the design equations are investigated by considering parameters of single-ridged fed-waveguide, double-ridged radiation waveguide and the electrical performances of array. Then, three typical slotted waveguide arrays are setup and simulated. The calculated results illustrate that the slotted ridgewaveguide antenna array,which is designed by themethod proposed in this paper, has thewidest bandwidth,where the work band is from9. 4 to 10. 1GHz, inwhich the VSWR and the magnitude-phase insistence of each element are excellent. The validity of this design method is confirmed and the fed-divider design is suitable for slotted ridge waveguide antenna in any frequency and dimension. © Springer India 2016. Source

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