Gürel, LeventManyas, AlpErgül, Özgür2016-02-082016-02-082007http://hdl.handle.net/11693/26994Date of Conference: 11-16 November 2007Conference Name: 2nd European Conference on Antennas and Propagation, EuCAP 2007The multilevel fast multipole algorithm (MLFMA) is a powerful tool for efficient and accurate solutions of electromagnetic scattering problems involving large and complicated structures. On the other hand, it is still desirable to increase the efficiency of the solutions further by combining the MLFMA implementations with the high- frequency techniques such as the physical optics (PO). In this paper, we present our efforts in order to reduce the computational cost of the MLFMA solutions by introducing PO currents appropriately on the scatterer. Since PO is valid only on smooth and large surfaces that are illuminated strongly by the incident fields, accurate solutions require careful choices of the PO and MLFMA regions. Our hybrid technique is useful especially when multiple solutions are required for different frequencies, illuminations, and scenarios, so that the direct solutions with MLFMA become expensive. For these problems, we easily accelerate the MLFMA solutions by systematically introducing the PO currents and reducing the matrix dimensions without sacrificing the accuracy.EnglishHybrid techniquesMultilevel fast multipole algorithm (MLFMA)Physical optics (PO)Complex targetsComplicated structuresComputational costsDifferent frequencyDirect solutionElectromagnetic scatteringRadar cross section (RCS)Conference Paper10.1049/ic.2007.1167