Yu Fan

A perturbation particle swarm optimization for the synthesis of the radiation pattern of antenna array

In this paper, a modified particle swarm optimization algorithm is proposed, in which special techniques such as global best perturbation and inertia weight jump threshold are adopted. The convergence speed and accuracy are improved. Using it, the problems such as prematurity and easily trapping in local optima can be avoided. The experiments of some benchmark functions demonstrate that it achieves relatively high performance. Optimization of the radiation pattern of antenna array using the PPSO is also presented.

Synthesis of antenna arrays using a modified complex number coded genetic algorithm

A complex number coded genetic algorithm (GA) is proposed; it can be used in the synthesis of antenna array patterns. Unlike a conventional GA using binary coding and binary crossover, this method directly represents the array excitation weighting vectors as complex number chromosomes and uses linear crossover. For fast convergence, this algorithm uses the three chromosome linear crossover method. Compared with conventional GAs, this algorithm has a few advantages: giving a clearer and simpler representation of the problem; simplifying chromosome construction; totally avoiding binary encoding and decoding. Computer simulations show that it can be used as a general tool for the synthesis of antenna array patterns.

Detection and Parameter Estimation of LFM Signal Using Integration of Fractional Gaussian Window Transform

In this paper, Integration of Fractional Gaussian Window transform (IFRGWT) is proposed for the parameter estimation of linear FM (LFM) signal; the proposal is based on the integration of the Fractional Fourier transform modified by Gaussian Window. The peak values can be detected by adjusting the standard deviation of Gaussian function and locating the optimal rotated angles. And also the parameters of the signal can be estimated well. As an application, detection and parameter estimation of multiple LFM signals are investigated in low signal-to-noise ratios (SNRs). The analytic results and simulations clearly demonstrate that the method is effective.

FPGA implementation of downlink DBF calibration

The calibration system is very important in solving the amplitude and phase imbalance of the digital beam forming (DBF) antennas. In this paper, a hardware calibration system based on field programmable gate array (FPGA) is designed. The calibration algorithm adopted in this design is based on the parallel orthogonal codes. To improve the calibration speed, parallel design methods are used. The simulation result shows that this system can satisfy the request of the real time calibration of the downlink digital beam forming.

An improved model for simultaneously measuring distributed microbending and temperature using fully distributed optical fiber sensor by optical frequency-domain reflectometry

An improved RROFDR theoretical model is presented, which simultaneously measure distributed temperature and microbending using a fully distributed optical fiber sensor by optical frequency-domain reflectometry. The relation between the frequency and time is studied, and the model between the v domain and z domain is given. The calculation result is almost consistent with the real one.

The study on shielding methods to electromagnetic radiation from DC electronic motor in HAPS

The electromagnetic compatibility (EMC) problem of high altitude platform systems (HAPS) is studied in this paper. A physical model for electromagnetic interferences (EMI) of electromagnetic radiation of spark discharge in DC electric motor is proposed. Based on this model, EMI frequency points has been estimated by equation approximatively for the given structure and size of a motor. Two methods are taken to shield electromagnetic radiation, the 1st one is to mount a perfect conductor block near the DC electric motor (EMI source), which results in the voltage magnitude falling 20 /spl sim/ 37dB in antenna ports. The 2nd one is to mount a perfect conductor board near the antenna array (sensitive element), and the voltage magnitude of antenna ports falls 5dB at least. Both are valid to shield electromagnetic radiation, but the method to mount a perfect conductor block near the EMI source is more effective.

Convergence analysis of least squares general modulus algorithm in beamforming applications

The convergence behavior of least squares general modulus algorithm (LSGMA), a generalized form of least squares constant modulus algorithm (LSCMA) in adaptive beamforming applications, is analyzed under several signal environments. Monte Carlo simulation results are also given in terms of output SINR gain and iteration number required for convergence. It is shown that fastest convergence speed can be achieved by LSGMA when modulus exponent equals -1 and the corresponding output signal quality does not deteriorate.

A pre-FFT OFDM adaptive antenna array based on beam-space channel estimation

The adaptive antenna array used in OFDM systems has been an interesting topic in recent years. A modified pre-FFT antenna array scheme is proposed, in which the beam-space channel state information (CSI) estimation is adopted. A uniform linear antenna array is considered. It is confirmed by simulations that the proposed scheme performs much better than the element-space one, especially when strong interference is present. In the element-space scheme, CSI estimation is made on the array elements, which is not robust and is likely to fail under strong interference.

An efficient full-wave model for characteristic parameter extraction of CPWs

In this paper, a full-wave model to extract parameters of CPWs is proposed and its performance is examined by numerical simulations. Due to the adoption of an asymptotic Green function and analytic processing, a great reduction of the CPU time cost of the spectral domain integral has been achieved. Meanwhile, the full-wave feature of the method ensures the accuracy of results.