Summary
International Symposium on Antennas and Propagation
2010
Session Number:3TE2
Session:
Number:3TE2-1
Improvement on the Invalidation in NURBS MOM-PO Method
Kai Huang, Zhi-Li He, Xun-Wang Zhao, Chang-Hong Liang, Hang Su,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
In 1992, J. Perez [1] first introduced the NURBS surface modeling technology into the field of high frequency electromagnetic computation. This technology has many advantages, such as high in modeling precision, few in the number of surfaces and so on. Therefore, electromagnetic computational methods based on NURBS modeling [2-5] have been widely analyzed since 1992. In 2007, MOM-PO was utilized to calculate the disturbed radiation pattern of antenna around a platform modeled by NURBS surfaces by Ming Chen [5] etc., and satisfying effects were obtained. In the last part of Ref. [5], however, it is pointed out that "One important issue is how to deal with cases when antenna is very close (less than one wavelength) or even connected to the platform.", which implies that the method is invalid when the distance between antenna and scatterer is less than one wavelength. By careful analysis, we have found that the invalidation is resulted from the SPM used in [5]. In fact, SPM is invalid in the computation of near field, and this invalidation leads to the incorrect impedance matrix element, and then to the wrong current distribution over the antenna, which is obtained by modifying the impedance matrix. In order to recover this invalidation, we attempt to calculate the scattered field in near field region by using Ludwig integral instead of the SPM. It is found that the validity and accuracy of this method are reasonable whether the distance from antenna to surface is less than one wavelength or not.