Michiko Kuroda

Computational algorithm of FDTD method for the Lorentz transformation

In this paper, new computational algorithm of FDTD method is proposed to analyze the electromagnetic field moving with higher velocity value. To apply the Lorentz transformations to FDTD method, at least two frames are required in calculation. But it is difficult to introduce two frames, rest frame and moving frame, in FDTD method. Here, by using two overlapped meshes, it makes possible to use these two frames in FDTD method. The new scheme of the calculation parameter was shown and as the easy example, the received wave at the observation point is calculated when the observation point moves for arbitrary directions. The numerical results were compared with the theoretical results and good agreements were obtained.

Dynamic and electrical analysis of MEMS capacitor with accelerated motion effects

MEMS technology is growing rapidly in RF field, because of the advantage over p-i-n diode or FET switches. An accurate knowledge of the electromagnetic field evolution around a moving or rotating body is very important for the design, optimization and realization of new optical devices or microwave devices, such as the RF-MEMS structures. We propose the numerical technique based on the finite-difference time-domain method with an adaptive implementation of grid generation. This simulation method is applied to the analysis of a two-dimensional MEMS variable capacitor with accelerated motions. The acceleration of the MEMS capacitor is derived under the equilibrium between the spring force and electrical force. Using this acceleration, the numerical results that express the relationship between the acceleration of the plates and the spring constant and the mass of the plates are shown.

Comparative study of over set grid generation method and body fitted grid generation method with moving boundaries

In this paper, the received wave at the observation point is calculated when observation point moves. It can be shown that the frequency of the received wave is shifted. To verify the over set grid generation method, numerical results are compared with the body fitted grid generation method and the theoretical results. Good agreements are obtained in these three results. The over set grid generation technique is easier to use for the moving boundary problems. We believe that these numerical techniques will have great promises for the analysis of the moving boundary problems in electromagnetic field.

Numerical technique for the analysis of transient effect of electromagnetic wave from moving plates in time domain and spectral domain

In this paper, electromagnetic field propagated from a moving plate in three dimensions is analyzed in time domain and spectral domain. Some numerical results are compared with the stationary ones and it can be shown that the frequency in the received wave is shifted.

A study of the accuracy in FDTD algorithm for solving EM field with rotating body

In this paper, FDTD method combined with Overset Grid Generation method is proposed to the analysis of the EM fields around a rotating body. We have previously proposed this numerical approach for a stationary and uniformly moving body. Lorentz transformation is combined to the analysis to comprise with the high relative velocities. The results of the numerical analysis show the modulations of the observed waveform when the incident wave hits the rotating body. The relativistic effects and its influence to the EM waveforms are presented. The modulations of EM fields in different radius length of observation point are also shown. The observed EM waveforms are compared with the theoretical results and achieved good agreements in high relative velocities, up to ν = 0.7c closed with the finite speed of light.

Numerical Technique for the Analysis of 3D MEMS Structures with Sinusoidal Motion

In this paper, the modeling technique of 3D MEMS structures with sinusoidal motion is proposed. This technique is a combination of the FDTD method and the body fitted grid generation technique. The numerical results of the field plot is shown for a MEMS capacitor with sinusoidal motion and demonstrate its unique computational advantages in the modeling of microwave devices and/or optical devices with moving boundaries

Numerical modeling of antennas with mechanically/MEMS-enabled moving parts

A numerical technique for the design, optimization and realization of antennas with mechanically/MEMS-enabled moving parts is proposed. The accuracy of this technique is evaluated through the calculation of the numerical results that express the relation between the velocity of the moving parts and the S11 parameters.

Numerical technique for wireless communication system with high speed movement

Numerical technique for the analysis of EM field with high speed moving dielectric body by using FDTD method with Overset Grid Generation method considering Lorentz transformation is presented. The characteristic of EM field when incident wave hits the moving dielectric body with high velocity value are analyzed. The accuracy of the proposed technique is validated. Good agreements are obtained between numerical results and theoretical results. The development of this numerical technique will give a great impact for many areas, particularly for the future high speed mobile communication systems used in transportation and aerial radar systems to detect the high speed motion of a moving boundary.

The development of novel numerical technique for the analysis of the moving vehicle and moving source

The numerical technique for the analysis of the electromagnetic field with moving body or a moving source are required for the effective modeling of new optical devices or microwave devices and also mobile communication field. We have previously proposed the Overset Grid Generation method coupled with FDTD method for the analysis of the EM field with moving boundaries considering Doppler Effect. For higher velocity value, Lorentz transformation is applied to the FDTD method. The time components that were changed in Lorentz transformation are fixed by using linear interpolation scheme in the Overset Grid Generation method. This allows a coherent point in time component with the FDTD method, which is an important element of this proposed numerical technique.

FDTD analysis of EM field effected by the motion of source and vehicle

A numerical technique for the analysis of the electromagnetic (EM) fields by moving sources and moving bodies can be significantly important for the realization of next generation nano-electronic devices particularly for mobile communication system. However, most of the analysis were primarily focused on the stationary source. We have previously proposed the Overset Grid Generation method combined with the FDTD method for the analysis of the EM field with moving body. In this paper, this technique is applied for the analysis of the EM field in a street cross section from moving vehicle and moving source. Here, the Doppler effect is observed by the moving vehicle and moving source.