Yi-Gang Wang

An Unconditionally Stable One-Step Leapfrog ADI-BOR-FDTD Method

In this letter, an unconditionally stable one-step leapfrog alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method for body of revolution (BOR) is proposed. It is more computationally efficient while preserving the properties of the original alternating-direction-implicit body of revolution finite-difference time-domain (ADI-BOR-FDTD) method. Due to the singularity, some field components on and adjacent to the axis are treated especially. To verify the accuracy and efficiency of the method, the scattered field from a PEC cylinder with a notch is calculated.

One-Step Leapfrog ADI-FDTD Method in 3-D Cylindrical Grids With a CPML Implementation

A three-dimensional (3-D) unconditionally stable one-step leapfrog alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method in the cylindrical coordinate system is presented. It is more computationally efficient while preserving the properties of the two-step scheme. By reusing the auxiliary variable, it also uses less memory than the two-step scheme. In contrast with the one-step leapfrog ADI-FDTD method in the Cartesian coordinate system, some implicit equations of the one-step leapfrog ADI-FDTD method in the cylindrical coordinate system are not tridiagonal equations. The Sherman Morrison formula is used to solve them efficiently. To solve open region problems, convolutional perfectly matched layer (CPML) for the one-step leapfrog scheme is proposed. Numerical results are presented to validate them.

One-Step Leapfrog LOD-BOR-FDTD Algorithm with CPML Implementation

An unconditionally stable one-step leapfrog locally one-dimensional finite-difference time-domain (LOD-FDTD) algorithm towards body of revolution (BOR) is presented. The equations of the proposed algorithm are obtained by the algebraic manipulation of those used in the conventional LOD-BOR-FDTD algorithm. The equations for -direction electric and magnetic fields in the proposed algorithm should be treated specially. The new algorithm obtains a higher computational efficiency while preserving the properties of the conventional LOD-BOR-FDTD algorithm. Moreover, the convolutional perfectly matched layer (CPML) is introduced into the one-step leapfrog LOD-BOR-FDTD algorithm. The equation of the one-step leapfrog CPML is concise. Numerical results show that its reflection error is small. It can be concluded that the similar CPML scheme can also be easily applied to the one-step leapfrog LOD-FDTD algorithm in the Cartesian coordinate system.

An Efficient Laguerre-Based BOR-FDTD Method Using Gauss–Seidel Procedure

In this paper, an efficient Laguerre-based body of revolution finite-difference time-domain (BOR-FDTD) method is proposed. A perturbation term and the Gauss-Seidel method are introduced to get the new algorithm. The splitting error caused by the perturbation term can be reduced to a low level by using the iterative method. To be different from its counterpart in the Cartesian coordinate system, the perturbation term used for the off-axis field is not applicable to the field on the axis in the proposed method. On the axis, it is not necessary to add the perturbation term and no nonphysical intermediate variable is involved. No splitting error compensatory term is used for the field on the axis during the iteration. Another difference is that the perturbation term in the proposed method causes a pronounced splitting error on the field point which is close to the axis. Several local iterations near the axis are needed since the splitting error near the axis is especially large. To validate the proposed method, two numerical examples are given. Numerical results show that it obtains a good convergence. Meanwhile, the comparison of the computational expenditure between the proposed method and several other methods indicates its performance.

Electromagnetic-thermal coupling computation of the high power microwave feed output window

This work develops a hybrid finite-difference time-domain (FDTD) method to calculate the electromagnetic field and temperature distribution of the high power microwave feed output window. First, the electromagnetic field of the microwave feed is computed, by which the electromagnetic heating source of the output window can be obtained. Then the partial differential equation of heat conduction is solved numerically. The influence of the temperature on electromagnetic parameters is considered in the model. The calculation is performed in the two-dimensional (2-D) cylindrical coordinate system, in which conformal FDTD techniques are used to handle the oblique PEC wall of the feed and cylindrical CPML is used to truncate the computational domain. The model is validated by the calculation results. The proposed method can be used in the analysis of unsteady temperature field of the output window.

Numerical simulation of the coaxial transmission line with an opening horn

In this paper, a coaxial transmission line with an opening horn is simulated by using the finite-difference time-domain (FDTD) method. Since the coaxial transmission line is rotationally symmetrical, the simulation is performed in two-dimensional (2-D) cylindrical coordinate system. The deformed Yee cells near the curved PEC of the opening horn are handled by the conformal FDTD techniques. The computational domain is truncated by the PML absorbing boundary condition. Numerical results are given and some discussions are made.

Simulation analysis of frequency selective surface with high power handling capability

An analysis of frequency selective surfaces (FSSs) with high power handling capability is presented in this paper. Maximum field enhancement factor (MFEF) is applied to quantify the power handling capability of FSSs. The effects of various design parameters on the MFEF and frequency response of FSSs are investigated using split finite-difference time-domain (split-FDTD) method. It is observed that the unit cell size, gap width and distance between two slot arrays are the main factors which affect the peak power handling capability of FSSs. Through the parameters optimization, the MFEF of FSSs decreases about 1.8 times comparing to the FSSs without optimization. The calculated frequency response and MFEF demonstrate three advantages of the FSS after optimization: insensitivity to the angle and polarization of incident waves, a relatively flat pass-band and lower MFEF. This kind of FSSs can be especially useful for airborne radar-dome which might be attacked by high power electromagnetic pulse weapons.