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Plane wave scattering from a circular conducting cylinder and a circular conducting strip has been formulated by equivalent surface currents which are postulated from the scattering geometrical optics (GO) field. Thus derived radiation far fields are found to be the same as those formulated by a conventional physical optics (PO) approximation for both E and H polarizations.
Ying YAN Xunwang ZHAO Yu ZHANG Changhong LIANG Zhewang MA
In this paper, a novel hybrid technique for analyzing complex antennas around the coated object is proposed, which is termed as “iterative vector fields with Physical Optics (PO)”. A closed box is used to enclose the antennas and the complex field vectors on the box' surfaces can then be obtained using Huygens principle. The equivalent electromagnetic currents on Huygens surfaces are computed by Higher-order Method of Moments (HOB-MoM) and the fields scattered from the coated object are calculated by PO method. In addition, the parallel technique based on Message Passing Interface (MPI) and Scalable Linear Algebra Package (ScaLAPACK) is employed so as to accelerate the computation. Numerical examples are presented to validate and to show the effectiveness of the proposed method on solving the practical engineering problem.
Jose Manuel TABOADA Fernando OBELLEIRO Jose Luis RODRIGUEZ Jose Oscar Rubiños LOPEZ
This paper shows a comparison between several procedures to represent the Physical Optics (PO) current density into a hybrid Moment-Method-Physical-Optics (MM-PO) code. Some numerical results demonstrate that a set of basis functions suitable for the Method of Moments (MM) may be inappropriate to model the PO currents. A new evaluation of the PO operator is proposed. The radiation can be analytically determined and, since it includes a linear interpolation of the phase, it can be applied over large triangular domains. This allows a drastic reduction of the computational cost, maintaining or even improving the level of accuracy.
This paper first gives the exact surface integral representation for PO diffracted electromagnetic fields from bounded flat plate through the deformations of the original surface by using field equivalence principle. This exact representation with the surface integral can be approximately reduced to novel line integral along the boundary of the plate by the use of Maggi-Rubinowicz transformation, which keeps a high accuracy even in near zone. Numerical results for the scattering of the electric dipole wave from the square planar plate are presented for demonstrating the accuracy.
Suphachet PHERMPHOONWATANASUK Chatchai WAIYAPATTANAKORN
Beam reconfiguration by structural reconfigurable antenna, such as the small multi-panel reconfigurable reflector antenna, has an aspect of great concern, that is the effects due to the use of a number of small panels to form the reflecting surface. It is thus a matter of great interest to numerically investigate all possible factors affecting the performance of this type of antenna such as: neighboring panels blocking, diffraction. The "null-field hypothesis" and PTD are employed to account for the effects of both phenomena on the main beam steering ability and the cross-polar level. In addition, the transformation of the polygonal flat domains into the square domains is applied in calculating the PO radiation field due to the various irregular polygonal flat sections of the arbitrary initial approximate reflector e.g., the flat circular reflector and the paraboloidal reflector. It is found that the main contribution to the total cross polarization is depolarization due to the finite size of the panels. The maximum cross-polar gain predicted using PTD is around -30 dB. The blocking effect has minor influence on cross-polarization. Both effects cause distortion on the co-polar pattern for the observer far from boresight but blocking has more influence than edge diffraction. Both effects have minor influence on the co-polar gain. The co-polar gain has variation of less than or equal to 0.07 dB in the flat case and 0.16 dB in the paraboloid case.