Many electromagnetic problems can be simulated by FDTD method. Mainly, we use orthogonal cartesian coordinate in normal situations when we deal with the electromagnetic problems. Because in most situations, the structures simulated are simply rectangular. But sometimes we may need to simulate the structures which are not rectangular like the sharps of arc and circle. For this kind of problems, the tranditional FDTD method no longer works, so the tranditional FDTD method must be modified to fit the simulation of irregular structures. Besides the FDTD method we mention above, we even combine it with non-uniform grid method in more applications. And the time to apply it is when the object simulated both has the rectangular and curved structures in the same time like the microstrip fed by the coaxial cable. The situations like that would be a good time to apply it.

Transient current surges resulted from the simultaneous switching of output buffers in the high-speed digital circuits can induce significant ground bounce noise (GBN) on the chip, package, and printed circuit board (PCB). The GBN not only causes the signal integrity (SI) problems, such as glitches or timing push-out of signal traces, but also increases the electromagnetic interference (EMI) in the high-speed digital circuits. With the design trends of digital circuits toward higher speed, low voltage level, smaller volume, the impact of GBN has become one of the most important issues that determine the performance of electronic products. Adding decoupling capacitors between the power and ground planes is a typical way to suppress the GBN. However, they are not effective at the frequencies higher than 600MHz due to their inherent lead inductance. Recently, a new idea for eliminating the GBN is proposed by designing electromagnetic bandgap (EBG) structure with high impedance surface (HIS) on the ground or power plane. Several new EBG power/ground plane designs have been proposed to broaden the stopband bandwidth for suppressing the GBN. However there are some drawbacks, such as high cost, large area occupation and complicated fabrication process. In this paper, we propose a novel Hybrid EBG power planes for PCB or package to suppress the GBN. Its extinctive behavior of broadband suppression of GBN (over 10GHz) is demonstrated experientially and numerically. Finally, we combine the periodic high-low dielectric material with the EBG power plane to control the position and bandwidth of stopband.

The disadvantage of FDTD method is that it needs a long simulation time, and it is difficult to simulate a complex circuit. The methods to improve the efficiency in FDTD simulation are increase in width of time step, enlargement in space grid and extrapolation of late time records. In this paper, we predict the late time record in FDTD simulation by applying Prony¡¦s method, and save the computation time of FDTD simulation. The cost of computation time of Prony¡¦s method is low, and it has a good result that applying Prony¡¦s method at predicting a waveform which resonates with period. In this paper, we try to make a rule for finding training start point and width of training period in Prony¡¦s method. The result of prediction with a short period of time records under the rule is accurate and reliable

A full wave finite-difference time-domain method (FDTD) combined with thin-wire and thin-slot algorithms to analyze a metamaterial fabricated with periodic mushroom structures, is proposed in this dissertation. This proposed method is suitable for analyzing problems involving large structures with fine structural details. A periodic analysis for mushroom structures is presented. Only a single unit mushroom cell is required to present the phenomena of infinite periodicity with the help of periodic boundary conditions (PBCs). The composite right-/left-handed (CRLH) transmission line (TL) approach is introduced and used to approximate CRLH metamaterial through lumped L and C. Finally, several CRLH metamaterial mushroom-based structures are investigated. A 19 by 8 flat microwave lens and a parabolic microwave lens structure composed of 410 unit mushroom cells are investigated. These structures demonstrate negative refractive index (NRI) characteristics while operate in the left-hand (LH) region. The simulation and measurement results of one- and two-dimensional CRLH mushroom-based structures are compared.

The trends of present design in electronic systems are towards high speed, small size, and lower voltage levels. The noise immunity of high speed digital circuit decreases. ESD problem becomes more and more important for electric products because of the triboelectricity caused by human body with synthetic material. In this thesis we introduce the phenomenon in real life ESD caused by a charged human body source. Then we provide a good measurement method of ESD which enhances the repetition that gives a reliable and accurate result. Finally we try to build the numerical model for the air and contact discharge simulation by FDTD to provide a good measurement validation.

Because the metal enclosure with apertures is the structure of the cavity form, FDTD method belonging to full-wave analytical algorithm isn¡¦t efficient for analyzing such case. Thereby the ETL method belonging to analytical formulation provides another way to analyze it. Although the structure which it can apply to isn¡¦t as complex as that in full-wave analytical algorithm, the computing time is shorter than FDTD. In contrast, the method can¡¦t get good agreement. Thus two improved ways are introduced in this paper. One is to make the suitable structure wider and the other is to consider the higher mode original ETL method isn¡¦t included to improve the accuracy. Further these two ways make the suitable range of the method wider and the method has good practicability.

Developing full-wave simulators for high-frequency circuit simulation is a topic many researchers have investigated. Generally speaking, methods invoking analytic pre-processing of the device¡¦s V-I relations (admittance or impedance) are computationally more efficient than methods employing numerical procedure to iteratively process the device at each time step. For circuits providing complex functionality, two-port or possibly multi-port devices whether passive or active, are sure to appear in the circuits. Therefore, extensions to currently available full-wave methods for handling one-port devices to process multi-port devices would be useful for hybrid microwave circuit designs. In this dissertation, an efficient scheme for processing arbitrary multi-port devices in the finite-difference time-domain (FDTD) method is proposed. The device¡¦s admittance is analytically pre-processed and fitted into one grid cell. With an improved time-stepping expression, the computation efficiency is further increased. Multi-port devices in the circuit can be systematically incorporated and analyzed in a full-wave manner. The accuracy of the proposed method is verified by comparison with results from the equivalent current-source method and is numerically stable.

In this paper,we used Finite-Difference Time-Domain Method to Analyze CPW and Antenna.In CPW ,we had to process excitiation source and ABC.Or we couldn`t get correct result.In antenna analysis,we used KSIR to calculate antenna pattern.

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