Dagang Xie

Microwave reduction of square Sierpinski factal based metallo-dielectric structure

The microwave reduction of square Sierpinski fractal based metallo-dielectric structure is studied. We find that microwave reduction is obtained for the structure with frequency about 6–10GHz, especially more than 30dB from 7.5GHz to 9GHz, by finite element method (FEM). And the measured data have verified the validity of computation. Furthermore, we have presented a fitting linear equation and a fitting curve to describe the relationship between reduction peak frequency vs dielectric thickness. These may have application in stealth of aircrafts or ships and the design of Frequency Selective Surfaces.

Computation of shielding effectiveness of a rectangular case with MLFMM between 0–5GHz

The multilevel fast multipole moment method (MLFMM) is employed to compute the electric and magnetic field shielding effectiveness of a normal case with a classic rectangular aperture. The calculated values of shielding effectiveness by MLFMM are in good agreement with measurements and calculated data by Transmission Line Method (TLM). In addition, the variation characters of shielding effectiveness with frequency are obtained. In particular, the drastic change of electric field shielding effectiveness is almost from 1.75GHz-3.1GHz, while magnetic field shielding effectiveness is not rather violent. As part of this work, we also investigate some other coupling characteristic quantity, such as the distribution of surface current and charges. Our results are more instructive for the electromagnetic protection design, especially in higher frequency band.

The simulation of Specific Absorption on human head model from nuclear electromagnetic pulse

In this paper, a human head from nuclear electromagnetic pulse (NEMP) is simulated by using CST program for the analysis of Specific Absorption (SA) in the human head at 1MHz, 30MHz, 200MHz, 300MHz, 350MHz and 400MHz. The human head model is homogeneous and simulated with the brain equivalent material. And the NEMP is described by a double exponential pulse shape with some characteristic parameters. From these results, we find that while the frequency is becoming higher, the peak SA first rise and then drop down. Whats more, the maximum of SA almost concentrate on the front of neck except for that at 1MHz. Therefore, the front of neck is the point to the NEMP protection. We believe that these results are very useful to the NEMP protection of human head.

The prediction and reproduction of synthesis electromagnetic environment for naval ship

For weapon platforms, synthesis electromagnetic fields usually occur. A method of predicting and reproducing synthesis electromagnetic environment for naval ship is introduced. And the corresponding test system is constructed. The method predicts the distribution of synthesis electromagnetic environment firstly. Then such environment can be reproduced with small power by using the reverberation chamber.

Scattering characteristic from a cylindrical Salisbury screen with 1rad

This paper presents radar cross section results from a MLFMM model of scattering from a cylindrical Salisbury screen with 1rad. Different from some previous researches, this study is concentrated on the results at high radar frequencies such as in I and J bands (9–11GHz). Both normal and off-normal incidence is considered. According to our calculated results by MLFMM, it exhibits better scattering performance than the same size plate. In addition, we find that in the angle range of 70–90°, a few data of the latter are smaller slightly than those of the former. However, we believe it may not affect the application in fact. Finally, in order to study the interaction between incident wave and the cylindrical Salisbury screen, the distribution of surface current and charges at 9.8GHz are presented.

Simulation of shielding characteristic of a typical decay waveguide window for EMP

This work simulates the shielding characteristic of a typical decay waveguide window for EMP. In the past, most researchers on electromagnetic protection have mainly focused their attention on the aperture coupling on the rectangular cavity. In contrast, the focus of this paper is not on it, but rather on the shielding characteristic of a typical decay waveguide window for EMP. The effect on EM coupling and shielding due to penetration through apertures behind it is also investigated. Here, the popular double exponential pulse has been used in the simulation of incident EMP. Full wave method of finite integration has been employed for the field strength at different points behind the window decay waveguide window. In addition, field nephograms are obtained for showing the whole shielding characteristic. Finally, the simulated results are verified with test data

An accurate and efficient shielding effectiveness evaluation of a rectangular enclosure with rectangular apertures

An accurate and efficient method to predict the shielding effectiveness (SE) of a rectangular enclosure with rectangular apertures is presented. A more accurate mathematical disposal is suggested for the calculation of slot impedance. And the point is to replace the former approximate expression by rigorous elliptical integration. Finally, the predicted results of the new method are compared with measured data and good agreement is reported.