Study, Improving And Application Of Pseudospectral Time-domain (PSTD) Algorithm Used In Transient Electromagnetic Field

The research work presented in this dissertation cover the characteristics of Time Domain Transient Electromagnetic Field(TDTEF) analysis method ,the particular analysis of Pseudospectral time-domain(PSTD) algorithm, the improved or hybrid algorithms of PSTD and it's application in high power ultra wide-band technology and photonic crystals design.Time Domain Transient Electromagnetic Field(TDTEF) is a frontier branch of modern electromagnetics. Due to its advantages of concretion, extensive applicability and facilitation of Frequency-Analysis, the techniques of TDTEF got rapid progress in recent 20 years. In the first part of this dissertation, the characteristics, the range of application and the calculation efficiency of several TDTEF analysis methods are analyzed and compared. Then, PSTD algorithm is elicited because of it's high efficiency of calculation.As the foundation of this paper, the characteristics, the range of application and the calculation efficiency of PSTD algorithm are investigated in the second part. Absorbing Boundary Conditions (ABC) used in PSTD , including its rationale, performances and applications are discussed. At the same time , In order to eliminate Gibbs phenomenon, two or three methods of source implementation are introduced.To widen the application of PSTD algorithm, a new non-uniform pseudospectral time-domain (UNPSTD) algorithm is developed in the latest years, and it is highly desirable. In the third part of this dissertation, UNPSTD based on non-uniform fast Fourier transform (NU- FFT) and grid transform are introduced respectively. The advantages and shortcoming of these algorithm are discussed also.in order to improve the efficiency and precision of calculation or the range of application, the forth order time stepping PSTD, combined algorithm PS-FDTD in different dimension and hybrid algorithm PS-FDTD in same dimension are investigated one by one. The characteristics of these algorithms are also discussed in this part.As a highlight of this dissertation, the PSTD algorithm is introduced to high power ultra wide-band(UWB) technology and used to solve electromagnetic problems with electrical-large objects such as the transmission and scattering of UWB impulse in multiplayer medium, in building and the design of UWB antenna. Good agreement between the calculated data using PSTD method and those from experiments or calculating by FDTD proves that PSTD is an effective method in the analysis of high power ultra wide-band(UWB) electromagnetic problem with electrical-large objects. It will be more widely used in the future.The last part of the dissertation, photonic crystals with periodic structure are studied using PSTD algorithm. The influence of several electric parameters and structural parameters (such as geometry and layer number of photonic crystals) to photonic band-gap(PBG), is also discussed in detail. The results of study will be usedful to guide the design of photonic crystal construction.