nzu Ji

Series expansion feasibility of singular integral in method of moments

When calculating electromagnetic scattering using method of moments (MoM), integral of the singular term has a significant influence on the results. This paper transforms the singular surface integral to the contour integral. The integrand is expanded to Taylor series and the integral results in a closed form. The cut-off error is analyzed to show that the series converges fast and only about 2 terms can agree well with the accurate result. The comparison of the perfect electric conductive (PEC) spheres bi-static radar cross section (RCS) using MoM and the accurate method validates the feasibility in manipulating the singularity. The error due to the facet size and the cut-off terms of the series are analyzed in examples.

A Novel Deduction of Stokes Parameters Based on 2-ordered Basis Matrices

Four two-ordered basis matrices were introduced to deduct Stokes parameter representing electromagnetic wave polarization. Two of them have algebra features similar to unity and imaginary of complex number, so an exponential function was defined which can easily express some matrix operation such as coordination rotation in 2-dimension. The other 2 basis matrices were also incorporated to deduce the Stokes parameters. The four matrices have some fatigue algebra structure which was incorporated in deduction. The coordinate transformation was converted to some matrix problems and we get a more concise result.

Study on Cylinder's Surface Current Density and Radar Cross Section (RCS) Resonance

Perfect electric conductive cylinders scattering is a typical 2-dimensional scattering and has accurate solution which is very helpful in study of conductors surface wave, crawling wave and is often used for validation of computational algorithm. The surface currency densitys magnitude and phases distribution over the profile are studied and the incident polarization and frequencys influence on the surface currency are analyzed. The bi-static radar cross section (RCS) is calculated based on the far field approximation of Hankels function and the RCSs resonant characteristics over the frequency and bi-static angle are studied. Analysis results show that RCSs variations with frequency and bi-static angle are similar and the resonant peaks numbers are the same. This result has important reference meaning to study of RCSs frequency and multi-static features.

Mono Pulse Confocal Microwave Imaging in Breast Cancer Detection

Mono pulse algorithm for confocal microwave imaging (CMI) for breast cancer detection is presented in this paper. All the antennas are used as receiver but only one is also used as transmitter. The transmitted signal is emitted for only once, thus the gross electromagnetic wave energy to the breast is reduced and the diagnosis time can be saved. Two confocal microwave imaging algorithms are presented in this paper: delay-sum-max and delay-production-sum. Both algorithms use the same delayed backscattered signals as the convectional CMI. The difference is how to use the delayed signals to form the image of the scattering intensity. Delay-sum-max method adds the signal together to generate the different value in confocal point via coherent and incoherent addition. Delay-production-sum algorithm products the delayed signal so as to make the assigned value in the confocal point outside the tumor is nearly zero. The image results can be compliment for more confirm diagnosis. Finite-difference time-domain (FDTD) method is used for simulation on 3 models of different tumor arrangements. The results show both methods are effective in detecting single-tumor, while there are some limitations in dealing with multi-tumor.