Abstract:
Characteristic mode (CM) analysis is a popular tool for analyzing antennas and is available in standard simulation packages. Numerical implementations of characteristic modes are almost exclusively based on the method-of-moments (MoM) matrices as originally proposed by Harrington and Mautz and as such, the characteristic mode decomposition has been understood to be closely related to MoM. However, modern antenna design often relies on complicated shapes and nontrivial distribution of various materials, where simulation tools based on the finite element method (FEM) and the finite difference time domain (FDTD) are preferable to MoM.
Here, scattering-based formulations for characteristic modes are presented, resembling the original proposal by Garbacz. Formulations of characteristic modes as scattering problems are independent of the associated computational tools. This enables frequency-domain solvers such as the FEM and time domain solvers such as FDTD to complement classical MoM-based formulations in characteristic mode analysis. Formulations based on spherical waves (transition matrix) and plane waves (scattering dyadic) are presented and allow for CM decomposition of arbitrarily shaped objects, providing high numerical dynamics and increased stability, removing the issue of spurious modes, and offering good control of convergence. Moreover, an iterative algorithm is introduced to construct transition matrices and scattering dyadic, effectively reducing the computational complexity to approximately one CM per full-wave solver.
Properties of the scattering-based formulation are illustrated with canonical objects such as magneto dielectric layered spheres, simple CM geometries such as rectangular PEC plates, and more realistic cellular phone modes with a more complex mixture of metallic and dielectric parts.
Biography:
Mats Gustafsson received the M.Sc. degree in Engineering Physics 1994, the Ph.D. degree in Electromagnetic Theory 2000, was appointed Docent 2005, and Professor of Electromagnetic Theory 2011, all from Lund University, Sweden. He co-founded the company Phase holographic imaging AB in 2004. His research interests are in scattering and antenna theory and inverse scattering and imaging. He has written over 100 peer reviewed journal papers and over 100 conference papers. Prof. Gustafsson received the IEEE Schelkunoff Transactions Prize Paper Award 2010, the IEEE Uslenghi Letters Prize Paper Award 2019, and best paper awards at EuCAP 2007 and 2013. He served as an IEEE AP-S Distinguished Lecturer for 2013-15.
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