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Papers by miroslav djordjevic

IEEE Transactions on Antennas and Propagation, 2004

A novel double higher order Galerkin-type method of moments based on higher order geometrical mod... more A novel double higher order Galerkin-type method of moments based on higher order geometrical modeling and higher order current modeling is proposed for surface integral equation analysis of combined metallic and dielectric antennas and scatterers of arbitrary shapes. The technique employs generalized curvilinear quadrilaterals of arbitrary geometrical orders for the approximation of geometry (metallic and dielectric surfaces) and hierarchical divergence-conforming polynomial vector basis functions of arbitrary orders for the approximation of electric and magnetic surface currents within the elements. The geometrical orders and current-approximation orders of the elements are entirely independent from each other, and can be combined independently for the best overall performance of the method in different applications. The results obtained by the higher order technique are validated against the analytical solutions and the numerical results obtained by low-order moment-method techniques from literature. The examples show excellent accuracy, flexibility, and efficiency of the new technique at modeling of both current variation and curvature, and demonstrate advantages of large-domain models using curved quadrilaterals of high geometrical orders with basis functions of high current-approximation orders over commonly used small-domain models and low-order techniques. The reduction in the number of unknowns is by an order of magnitude when compared to low-order solutions.

1. Introduction Higher-order basis functions which constitute the large-domain (entire-domain) me... more 1. Introduction Higher-order basis functions which constitute the large-domain (entire-domain) method of moments (MOM) approach to integral-equation modeling of general 3-D electro-magnetic structures have significant computational advantages over ...

This paper presents our development of novel higher order electromagnetic (EM) modeling technique... more This paper presents our development of novel higher order electromagnetic (EM) modeling techniques for wireless technology applications based on the method of moments (MoM), finite element method (FEM), and physical optics (PO). Modern wireless systems involve electrically large EM structures (antennas, circuits, and components) that are very complex in both geometry and material composition. There is a clear need for advanced analysis and design tools for predicting the performance and optimizing the parameters of such structures prior to costly prototype development. In addition, EM tools are needed for indoor and outdoor propagation modeling, for assessing EM interactions with human bodies, etc. These tools have to be very accurate and reliable. Wireless designers also demand that the simulation techniques be fast and run on relatively small computing platforms, such as standard desktop PCs. Generally, MoM is very efficient at modeling of open-region (e.g., antenna/scattering) problems, while FEM is an excellent choice for modeling of closed-region (e.g., waveguide/cavity) problems. Finally, PO is extremely cost effective for structures that include electrically very large surfaces with slowly varying currents, especially when hybridized with MoM. 1 Our MoM technique is based on using generalized curvilinear quadrilaterals of arbitrary geometrical orders for the approximation of metallic and dielectric surfaces in conjunction with hierarchical divergence-conforming polynomial vector basis functions of arbitrary orders for the approximation of surface electric and magnetic currents, and we refer to it as a double-higher-order method [1]. Our FEM technique employs hierarchical curl-conforming vector basis functions of higher polynomial orders defined in generalized curved hexahedra of higher geometrical orders . The two techniques enable using large curved MoM quadrilaterals and FEM hexahedra that are on the order of two wavelengths in each dimension. Our hybrid MoM-PO technique uses hierarchical basis functions in the MoM region and higher order interpolatory polynomial functions in the PO region. This mixed approach results in an extremely fast and accurate EM tool.

IEEE Transactions on Antennas and Propagation, 2009

Abstract—A novel higher order large-domain hybrid compu-tational electromagnetic technique based ... more Abstract—A novel higher order large-domain hybrid compu-tational electromagnetic technique based on the finite element method (FEM) and method of moments (MoM) is proposed for three-dimensional analysis of antennas and scatterers in the fre-quency domain. The ...

IEEE Transactions on Antennas and Propagation, 2005

Abstract—An efficient and accurate higher order, large-domain hybrid computational technique base... more Abstract—An efficient and accurate higher order, large-domain hybrid computational technique based on the method of moments (MoM) and physical optics (PO) is proposed for analysis of large antennas and scatterers composed of perfectly conducting surfaces of arbitrary ...

IEEE Transactions on Antennas and Propagation, 2004

A novel double higher order Galerkin-type method of moments based on higher order geometrical mod... more A novel double higher order Galerkin-type method of moments based on higher order geometrical modeling and higher order current modeling is proposed for surface integral equation analysis of combined metallic and dielectric antennas and scatterers of arbitrary shapes. The technique employs generalized curvilinear quadrilaterals of arbitrary geometrical orders for the approximation of geometry (metallic and dielectric surfaces) and hierarchical divergence-conforming polynomial vector basis functions of arbitrary orders for the approximation of electric and magnetic surface currents within the elements. The geometrical orders and current-approximation orders of the elements are entirely independent from each other, and can be combined independently for the best overall performance of the method in different applications. The results obtained by the higher order technique are validated against the analytical solutions and the numerical results obtained by low-order moment-method techniques from literature. The examples show excellent accuracy, flexibility, and efficiency of the new technique at modeling of both current variation and curvature, and demonstrate advantages of large-domain models using curved quadrilaterals of high geometrical orders with basis functions of high current-approximation orders over commonly used small-domain models and low-order techniques. The reduction in the number of unknowns is by an order of magnitude when compared to low-order solutions.

1. Introduction Higher-order basis functions which constitute the large-domain (entire-domain) me... more 1. Introduction Higher-order basis functions which constitute the large-domain (entire-domain) method of moments (MOM) approach to integral-equation modeling of general 3-D electro-magnetic structures have significant computational advantages over ...

This paper presents our development of novel higher order electromagnetic (EM) modeling technique... more This paper presents our development of novel higher order electromagnetic (EM) modeling techniques for wireless technology applications based on the method of moments (MoM), finite element method (FEM), and physical optics (PO). Modern wireless systems involve electrically large EM structures (antennas, circuits, and components) that are very complex in both geometry and material composition. There is a clear need for advanced analysis and design tools for predicting the performance and optimizing the parameters of such structures prior to costly prototype development. In addition, EM tools are needed for indoor and outdoor propagation modeling, for assessing EM interactions with human bodies, etc. These tools have to be very accurate and reliable. Wireless designers also demand that the simulation techniques be fast and run on relatively small computing platforms, such as standard desktop PCs. Generally, MoM is very efficient at modeling of open-region (e.g., antenna/scattering) problems, while FEM is an excellent choice for modeling of closed-region (e.g., waveguide/cavity) problems. Finally, PO is extremely cost effective for structures that include electrically very large surfaces with slowly varying currents, especially when hybridized with MoM. 1 Our MoM technique is based on using generalized curvilinear quadrilaterals of arbitrary geometrical orders for the approximation of metallic and dielectric surfaces in conjunction with hierarchical divergence-conforming polynomial vector basis functions of arbitrary orders for the approximation of surface electric and magnetic currents, and we refer to it as a double-higher-order method [1]. Our FEM technique employs hierarchical curl-conforming vector basis functions of higher polynomial orders defined in generalized curved hexahedra of higher geometrical orders . The two techniques enable using large curved MoM quadrilaterals and FEM hexahedra that are on the order of two wavelengths in each dimension. Our hybrid MoM-PO technique uses hierarchical basis functions in the MoM region and higher order interpolatory polynomial functions in the PO region. This mixed approach results in an extremely fast and accurate EM tool.

IEEE Transactions on Antennas and Propagation, 2009

Abstract—A novel higher order large-domain hybrid compu-tational electromagnetic technique based ... more Abstract—A novel higher order large-domain hybrid compu-tational electromagnetic technique based on the finite element method (FEM) and method of moments (MoM) is proposed for three-dimensional analysis of antennas and scatterers in the fre-quency domain. The ...

IEEE Transactions on Antennas and Propagation, 2005

Abstract—An efficient and accurate higher order, large-domain hybrid computational technique base... more Abstract—An efficient and accurate higher order, large-domain hybrid computational technique based on the method of moments (MoM) and physical optics (PO) is proposed for analysis of large antennas and scatterers composed of perfectly conducting surfaces of arbitrary ...