Title :
Ray Optical Electromagnetic Far-Field Scattering Computations Using Planar Near-Field Scanning Techniques
Author :
Tzoulis, Andreas ; Vaupel, Thomas ; Eibert, Thomas F.
Author_Institution :
Inst. for High Frequency Phys. & Radar Tech., Wachtberg
Abstract :
For accurate scattering computations in the far-field of flat finite objects, field based ray optical methods cannot be used directly, since the finiteness of the objects is not considered in the formulations. In this paper, planar near-field scanning techniques are used to overcome this problem. In particular, scattered ray optical fields are first computed in a scanning plane in the near-field region of the involved objects and are transformed into the far-field afterwards using field expansions in terms of spectrum density functions of outgoing waves. Since evanescent waves are avoided in the scanning plane, sampling rates less than lambda0/2 can be used for restricted angle range around the normal direction to the scanning plane. Reduced accuracy at grazing directions of observation is overcome by combining solutions provided by several scanning planes. The proposed approach is applied in the postprocessing stage of the recently developed hybrid method combining the uniform geometrical theory of diffraction with the finite element boundary integral technique and with the multilevel fast multipole method.
Keywords :
computational electromagnetics; electromagnetic wave scattering; geometrical theory of diffraction; finite element boundary integral technique; flat finite objects; multilevel fast multipole method; planar near-field scanning techniques; plane wave spectrum expansions; ray optical electromagnetic far-field scattering; scattering computations; spectrum density functions; uniform geometrical diffraction theory; Density functional theory; Electromagnetic fields; Electromagnetic scattering; Geometrical optics; Optical computing; Optical scattering; Optical surface waves; Physical optics; Physical theory of diffraction; Radar scattering; Far-field scattering computations; multilevel fast multipole methods (MLFMMs); planar near-field scanning techniques; plane wave spectrum expansions; ray optical methods;
Journal_Title :
Antennas and Propagation, IEEE Transactions on
DOI :
10.1109/TAP.2007.915436