Finite-difference time-domain (FDTD) full-wave analysis of several waveguide junction circulators with full-height ferrite posts of arbitrary shapes is presented. The structures contain T-junction, irregular T-junction, Y-junction, and Y-junction with a bend. Two ferrite shapes of interest are studied, including circular cylinder and triangular post, and the performance of the circulators is presented. Calculation results of the waveguide-junction circulators with circular ferrite post and triangular ferrite post obtained by the present analysis are compared with those from the field-matching and finite-element methods, respectively, as a reference, and better agreement is found in this study.

An electromagnetic beam that is not the solution to the paraxial wave equation but is the solution to Maxwell's equation is simulated directly by the finite-difference time-domain method. Electrical and magnetic field components of the beam are presented graphically. Then the diffraction of the electromagnetic beam pulse by an aperture in a conducting screen is analyzed. The fraction of the beam power through the aperture is defined and calculated. The fields in the time domain near the aperture, which show the diffraction by the aperture, are presented graphically.

This paper is aimed at analyzing the focal field of some axially-symmetric diffractive lenses with small F-number and electrically large radii which are used in millimeter wave focal imaging, especially for the case of a plane-wave incident onto the lenses obliquely, by using the method of moments (MoM). The analysis of a diffractive lens whose radius is as large as 78.3λ can be performed using appropriate pairs of basis functions and test functions in the MoM, and specific integration methods are adopted to integrate the oscillatory integrals which occurr in the MoM when it is applied on a body of revolution (BOR) for which the rotational symmetry of the BOR has been utilized. Comparison of the simulated results with the experimental data shows that the simulation is valid. An imaging experiment is carried out to show the ability of diffractive lens in a millimeter imaging system.

A design method for diffractive/refractive dielectric lens antennas working at millimeter wave band is presented in this paper. One surface of this kind of lens antenna is refractive and the other is diffractive. The refractive surface is used to control the amplitude distribution of the electromagnetic wave and the diffractive surface is used to adjust the phase distribution of the electromagnetic wave. The side lobe level of this kind of lens antenna is low due to the proper distribution of the field amplitude controlled by the refractive surface, and the thickness of the lens is very thin due to the use of the diffractive surface. Two design examples of the diffractive/refractive lens antenna are given, and their radiation patterns (fed with the corrugated horns) are computed using axially symmetric FDTD algorithm and presented in this paper.

In this article, an improved iterative arithmetic of the symmetric successive over-relaxation preconditioning biconjugate-gradient algorithm (ISSOR-PBCG) is utilized to solve the 3D edge FEM equations derived from the time-harmonic electromagnetic-field boundary value problems. Several typical structures have been analyzed, and the computation time is compared with that of other algorithms such as biconjugate-gradient (BCG) algorithm and the conventional symmetric successive over-relaxation preconditioning biconjugate-gradient algorithm (SSOR-PBCG). The CPU time saved using the ISSOR-PBCG algorithm is nearly 27% and 65.5%, as compared with that using the SSOR-PBCG and the BCG algorithm. It can be seen that the ISSOR-PBCG algorithm is efficient for edge FEM equation sets derived from large-scale time-harmonic electromagnetic-field problems.