Xu Penggen

Research on the electromagnetic scattering near the field

We calculate and analyze the scattering near the field from some simple and complex targets using the method of picture elements (PEL), based upon the method of high-frequency approximation. It introduces the critical distance of the near field and the far field which is related with the dimension of the target. The problem of the EMS near field from large size objects can be transformed to the problem of the far field by parting it to many very small size elements. By calculating the EMS near fields of some simple and complex targets based on the SCTE (scattering from complex targets and environments) system, the results show that there are much difference between the near field and the far field. And the characteristics of the near field are more complicated. This work has practical engineering value in the area of the electromagnetic compatibility (EMC), electromagnetic interference (EMI) prediction and electromagnetic scattering (EMS).

SCTE: RCS Prediction System for Complex Target and Interaction with Environment

A RCS prediction system named SCTE (Scattering from Complex Target and Environment) for calculating high-frequency electromagnetic scattering from complex target within complex environment is presented. The scattering body is described by Computer-Aided-Design (CAD) representations in which the complex body is modeled as NURBS (Non-Uniform Rational B-spline) surfaces. The complex environment (rough surface of sea or ground) is also carefully considered by using fractal function. Scattering fields are calculated by using physical optics and the equivalent currents methods. There is a good agreement between the present results and that from measurements which demonstrates the accuracy of this system.

Scattering of complex target within complex environment

This paper presents an RCS prediction system for calculating high-frequency electromagnetic scattering from complex target within complex environment. The scattering body is described by computer-aided-design (CAD) representations in which the complex body is modeled as NURBS surfaces (Non-Uniform Rational B-spline). The complex environment (rough surface of sea or ground) is also carefully considered by using fractal function. Scattering fields are calculated by using physical optics (PO) and the equivalent currents methods (MEC). There is a good agreement between the present results and that from measurements which demonstrates the accuracy of this system.

Research on the angular glint of targets in the near-zone

This paper presents a method to analyze and calculate the angular glint of targets. By parting the target to very small size cells, using high-frequency approximation, the near-field radar cross section (RCS) is calculated based on the scattering from complex targets and environments (SCTE) system, and the angular glint is calculated by the phase grads. The results show that the angular glint can be calculated exactly in the SCTE system, and this method is correct and efficient. In the near-zone, the far-field theory is not applicable and the angular glint should be calculated by the near-field theory.

Simulation of the RCS range resolution of extremely large target

The high frequency hybrid technique based on an iterative Physical Optics (PO) and the method of equivalent current (MEC) approach is developed for predicting range resolution of the Radar Cross Section (RCS) in the spatial domain. We introduce the hybrid high frequency method to simulate range resolution of the extremely large target in the near zone. This paper applies this method to simulate the range resolution of the two 1 m×1 m plates and the ship. The study improves the spced of simulating the range resolution of the extremely large target and is prepared for the application of the extrapolation and interpolation in the spatial domain.

Application of improved Z-buffer technique to RCS computation

This paper presents a new method for computation of the monostatic radar cross section (RCS) of electrically large conducting objects. Compared with the traditional Z-buffer technique, the improved one can record not only the illuminated surface of the body, but also the information about the shadowed part. So multi-scattering and RCS of cavity can be calculated. The second advantage of it is using dual representation, of the targets facet surface, in which the illuminated part is treated as bicubic patches for RCS calculation, and is simplified to flat facet when ray tracing is done. Excellent agreement with the experiment has been obtained.

Predicting the secondary electromagnetic reflection on the complex targets

This paper presents a quick and effective arithmetic to search geminate cells where secondary scattering exists between them, and establishes a secondary scattering theory model in the near-field. The secondary incidence field on a cell is decided by geometrical optics (GO). And physical optics (PO) decides the secondary scattering field. It can also be applied to far-field and near-field.

Study of Electromagnetism Compatibility of Bleeper Station

Transmitted power will decrease, cross-modulate distortion and inter-modulate distortion will be caused and antenna pattern will shift if transmitted antennas are fixed together. All these will lead to the alteration of area coverage. According to the basic theory of electromagnetism compatibility a computer model is established. We do some quantitative analysis of the problems above and give total number, arrangement mode and distance between antennas of bleeper station that operate at 150 MHz. The relation of these factors above are also given. All these are basis of the arrangement of antenna group of bleeper station.

A study on composite scattering of targets and environment

An analysis of the composite scattering between the target and the environment is made. The two-dimensionally fractal function is used to model the rough surface, and the scattered electromagnetic field is calculated by using Kirchhoffs approximation. The validity of the result is assured by some reference, which indicates that the methods in this paper are reliable, then a simple and practical example is given.

Investigation on the characteristics of the electromagnetic scattering near field from complex targets

Calculation and analysis of the scattering near field from some simple and complex targets using a method of picture elements (PEL) and a computer program are discussed. The analysis is based upon a method of high-frequency approximation. The uniqueness of this method is derived from the simplicity of the theoretical basis such as the physical optics (PO) and the vector potential. The calculated results show that there are large differences between the near field and the far field. The characteristics of the near field are more complex. This work has practical engineering value in the area of the electromagnetic compatibility (EMC), electromagnetic interference (EMI) prediction and electromagnetic scattering.