Yin Chengyou

Location accuracy of multistatic radars (TR/sup n/) based on ranging information

In modern ECM and ECCM environment, bistatic and multistatic radar systems have drawn increasing interest in many applications. It is well known that the position of a stationary or moving target can be estimated from measurements of the arrival times, directions of arrival, or Doppler shifts of electromagnetic waves received at various sites. An analysis based on ranging information for the target location accuracy of multistatic radar, with one transmitter and n receivers (TR/sup n/), is presented. The reasonable constellation of the system without knowing the transmitter position parameters is discussed. The geometric dilution of precision (GDOP) of the radar in a constrained space is also given.

Performance analysis of the estimation of time delay and Doppler stretch by wideband ambiguity function

In this paper, the performance of estimation of time delay and Doppler stretch by the wideband ambiguity function method (WBAF) is investigated. The comparison between the present result and that of Qu Jin et al. (see IEEE Trans., vol. SP-43, no. 4, p. 904-16, 1995) shows that the present result is more exact. Then we propose a modified returned signal model, and using the model we evaluate the maximum likelihood estimation (MLE) performance of the time delay and Doppler stretch, which shows that when the phase angle of the reflection coefficient /spl phi//sub 0/ is known, the MLE performance is similar to the result given by Qu Jin et al. in the case that /spl phi//sub 0/ is unknown. The result also demonstrates that WBAF method is an asymptotically optimal one.

On the asymptotic analysis of Cramer-Rao bound for time delay estimation

Starting with the most elementary probability formula of the Fisher matrix for time delay estimation in radar signals, a rigorously asymptotic expression of the Fisher matrix for time delay, Doppler shift and its higher derivatives, joint estimation is derived by using the asymptotic equivalent property of the Toeplitz matrix and circulant matrix, and the spectrum characteristics of circulant matrices. The present result is more accurate than the commonly used one. A comparison between the two results shows that under certain conditions the agreement of the two results is seen to be excellent.

Full wave analysis of arbitrary shape CCMA fed by microstripline

For solving Bessel functions singular problem of Sommerfeld integral in calculating the spatial domain Greens function of cylindrically stratified media, a domain-division algorithm is proposed in this paper, which can realize the computation for all elements of Z-matrix in the method of moment. Then, arbitrary shape cylindrical conformal microstrip antenna (CCMA) fed by microstripline is theoretically analyzed using the RWG basis function. A simulation example for investigating the effectiveness of the domain-division algorithm is present. Another simulation example is done to study the electromagnetic characteristics of a CCMA fed by microstripline, the results of which are compared with those of the counterpart planar antenna.

Analysis of the characteristics of scanning phased arrays with broadband and wide angle

Phased arrays made up of log-periodic dipole antennas can scan with broadband and wide angle. In this paper, a 2/spl times/4 array is analyzed with moment method. Programming with the language of Matlab, the input impedance, VSWR, gain and the current of each cells are calculated. The scanning directional graph of the azimuth and elevation is obtained. The results show that the phased array has the merits of high gain, broadband, strong scanning ability, and all this can be instructional to study and designing on short wave phased LPDA arrays.

Optimal excitations of LPDA arrays with network theories [log-periodic dipole antenna arrays]

The excitation for maximum power gain of antenna arrays is called optimized excitation, and it is analyzed theoretically, taking arrays as a multiport network. In different directions of the main beam of a log-periodic dipole antenna (LPDA) array, the excitation for maximum gain is calculated by a Matlab program. The characteristics of the array under optimized excitation are obtained, and the array is proved to have better capability. The database established can be instructional on further study of LPDA arrays.

Study on pulsed radiating characteristics of doublet antenna loaded by lumped resistors with FDTD method

The pulsed radiating characteristics of a doublet antenna loaded by Wu-King lumped resistors are studied by the 3D FDTD method. The electric current waveforms on the antenna and the far field radiation patterns are all given. The results illustrate that this loaded form can certainly improve the pulsed radiating waveform in space.

Multisensor measurement data association and its performance analysis

In this paper, the multiple hypotheses testing (MHT) data association method is derived for a multisensor system based on the priori information of the detection performance of each sensor, and its performance is analyzed in detail. The detection and false alarm probabilities for multisensor system are explicitly defined for the first time, and a calculation example and computer simulations are provided, which demonstrates that the agreement between the theoretical analysis and computer simulations is excellent.

The analysis and design of distributed detection based on star configurations

In this paper, the distributed detection problem for sensors with star configuration is systematically investigated under the assumption that the fusion rule is based on Neyman-Pearson (N-P) criterion. Then it is proved that local decision and local fusion rules should also be N-P tests in order to obtain global optimization. The computational method of the thresholds is presented for the case where the constant alarm false rate processors are used in each sensor. Finally some calculation examples are given, which demonstrate that the performance of the optimal distributed detection approaches to the one of central detection under unconstrained communication bandwidth. The results given in this paper are of important significance for the point or small area multisensor defense system.