Difference Method And Its Application To Transmission Line & Microstrip Antenna

The general transmission-line include bi-line and coaxial-line. With the development of space-electron, military and civil applications, the higher requirement of miniaturization, wide-frequency-brand and being easy to integrate for microwave components was brought up, and then the stripline and microstip-line appear. Analyse of transmission-line has important significance in engineering design application; On the other hand, anisotropy material is used in many fields, for example, magnetism anisotropy material ferrite is used in microwave and millimetre-wave apparatus, the chrematistic of changing by any biased magnetic field made it find its way not only in microwave integration but also in antenna technology. In our paper, the main studies about field distribution are done using the FD method and the radiating properties of a rectangular microstrip patch on lossy biased ferrite substrate are investigated using the FDTD method.FD method is based on difference principle, using each discrete node of function to substitute for partial derivative approximately, and so the problem to be resolved is changed into one group of corresponding difference equation. In our paper, the format of FD about two-dimension Poisson and Laplace equation are made. According to the given boundary conditions, Distribution of electric potential for several transmission line, corresponding characteristic impedance are given by using the FDTD method and using a new method to open-region truncation boundary condition. The calculating results compare with resolution to prove correctness of procedure.The main method to study microstrip antenna is TLM ,BEM, FDTD. In our paper, The tensor form of magnetized ferrite varies with the changing of biased magnetic field. In order to study the radiation characteristic of a microstrip antenna on ferrite substrate, the FDTD formulation in ferrite is derived. The radiating pattern of a rectangular microstrip patch antenna on lossy ferrite substrate is investigated by using the FDTD method when the substrate is biased by rotation magnetic field. The computed results show that changing the direction of biased field can control the radiation pattern. In the given example, the direction of radiation pattern can change about 30° while the external magnetic field is rotating 90° for a microstrip antenna working at 0.444GHz.