Investigation On Analysis And Design Of Microstrip Circuits Using FDTD Method

A direct three-dimensional finite-difference time-domain (FDTD) method is applied to the full-wave analysis of microstrip planer structures. Firstly, some simulation works have been done on the microstrip line, microstrip couple line, microstrip low pass filter and microstrip coupler, all the results show an excellent agreement with the results from the literature. After the validation of the FDTD method, we apply the FDTD method to microstrip bend, microstrip inductor, microstrip antenna analysis, and the results may be helpful in future microstrip circuit designs. In addition, we can easily extend these methods to analyze other kinds of microstrip structures.In order to fulfill the requirement of high performance narrow-band band-pass filters in modern wireless local area network (LAN), several novel types of dual-mode microstrip band-pass filters have been analyzed and optimized by applying the FDTD method. These filters are designed in a way that they operate in dual modes to ensure a good electric performance at the center frequency. They are designed to operate at either 2.4GHz or 5.25GHz, which are the frequencies allocated in the area of wireless local area network (LAN). The return losses for these filters are about -20dB and the insertion losses are about -2dB at the resonant frequency. Because of its smaller size, the structures can be applied in the area of the on-package highly integrated wireless transceiver systems. For enhancement of the electric performance around the resonant frequency at 2.4GHz, we also present a microstrip band-pass filter using two dual-mode meander loop resonators, although the size of the filter is increased, its FDTD simulation result shows the filter has a better frequency response.At last, in order to improve the efficiency, the GPOF method is used to extract the complex exponentials from the truncated time domain signal in FDTD simulations. According to the superposition of these complex exponentials, the function of time domain signal is formed, which efficiently extrapolate the remaining part of the signal without further FDTD execution. Therefore, that it can significantly save the time of computation by cooperating with FDTD, instead of pure FDTD calculation.