| With the dimensions of microwave circuits decreasing, especially in monolithic microwave integrated circuits (MMICs), it will be very difficult to make any adjustment after fabrication processes. So to analyze the microwave circuits more accurately is very important. However, when integration and working frequency of microwave planar circuits increase, some approximations made in the past will lead to great inaccuracy in this situation. How to narrow the gap between simulation and practice testing results is one of the most important problems of microwave circuits computer aided design(CAD). And what is more, studying the principles about the influences of these nonideal factors can help the designer get to know their effects early. When designing a microwave circuits, they can reduce the impact of these factors and balance the amount of calculation and precision of simulation.In this thesis, the nonideal characteristics of microstrip lines and coplanar waveguide are studied by the method of lines. The research results are as follows: The nonideal factors in microwave planar circuits are summarized and classified. The corresponding analytical modes are given.The peculiarities of application of the method of lines for various nonideal microwave planar transmission lines are studied. For example, the discrete methods for each nonideal microwave planar transmission lines are shown, and the system equations are gotten in both spatial and transform domain.Analyzed the effects of the noideal factors to the characteristics of microstrip lines and coplanar waveguide, such as shielding box, width of ground, strip thickness, width of substrate, composite-metal. Reasons of these effects are discussed and some useful principles about the influences of the nonideal factors are given.The nonideal characteristics of microstrip lines and coplanar waveguide are obtained by both simulation software and experimental test to verify the correctness of results getten by the method of lines. |
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