Tap Microwave Filters Analysis And Design

With the rapid development of modern microwave communication techniques, the spectrum is becoming more and more precious and crowded. The requirements for microwave filters with high selectivity, low loss, small size and low cost are increasing, which promotes the deeper research for the microwave filters.The tapped line input\output block with compact structures and flexible design method, was studied by many designers in the sixties and seventies of last century. But it is because the weak precision, hard tuning and long design period of traditional equivalent circuit method influences the development and wide use of this block.Now days, with the improvement of computer capacities and technique of microwave CAD, the precision and efficiency of the high frequency simulation softer is raising highly. So we can associate the equivalent circuit method with the softer of high frequency simulation, to improve the characteristics and shorten the design period.The purpose of this paper gives the deeper research of tapped line microwave filters, to provide the fast and precise design for the kinds of filters. The main works are as follows:1. The paper systematically describes basic concepts and theories that form the foundation for design of general microwave filters. The topics will cover filter transfer function, lowpass prototype filters, frequency transformations, immittance inverters and the passband insertion loss under the influence of the dissipation of filter elements2. The tapped line I/O block and the internal coupling structure is systematically analyzed. Two methods of analysis and design programs of filters are given .3. Some examples of filters are designed for special requirements, including combline, interdigital line and direct coupled. The analysis of any kinds is also given. At the last of partial examples, simulation results and measurements are given, which agree well with each other.In all,the paper systematically studies the tapped line microwave filters. The filters with compact size and good property are great suitable for the engineering.