Suspended Stripline Ultra-wideband Filter Design

In recent years,Ultra-wideband technology has flourished. As one of the most important Passive Components, Ultra-wideband filter has attracted more and more and more attention and research. In today's military and civilian communications, Ultra-wideband system means wide application prospects and enormous market value, and has far-reaching social and military significance.With the rapid development of wireless communication system, the communication frequency spectrum resource has become more and more lacking. The microwave filters,with Separation of useful and useless signal, has become one of most important communication system components, and the merits of its performance will directly affect the quality of communications systems.Now, Ultra-wideband microwave filter has been widely used in microwave, millimeter-wave communications, microwave navigation, guidance, remote telemetry, satellite communications and military electronic countermeasures, such as a variety of areas. Filter with smaller insertion loss, wide band, high power handling, good spurious performance and high selectivity is becoming customers'favorite. At the same time, size, cost and design speed are also the requirement of the clients. And this has prompted the microwave designers to make continually research and development of microwave filter design techniques.This article, which is based on suspended stripline, has combined with integrated filter design, studied the related theory and technology, and ultimately achieved ultra-wideband filter design. The main research contents are as follows:1 Introduction of UWB technology and filter requirements and analysis of the current development of ultra-wideband filter status and difficulty.2 From the filter design principle, it introduced the basic theory of microwave filters, commonly used filter types, and specific implementation of the microwave method.3 Theoretical analyses on the transmission characteristics of suspended stripline, especially the broad-side coupling structure whitch has special significance in the filter design.4 For Design method, it used the calculation software matlab programm to get initial value for parameters, and combined with three-dimensional electromagnetic simulation software HFSS to make model and do simulation analysis.Filter structure is High and low pass filter cascade. It processed separately low-pass filter, high-pass filter and the overall structure of the bandpass filter. On the filter was tested and compared, we has Obtained good results and verified the design theory and method.5 Through test comparison, it made the analysis the impact form port mismatch and the parasitic passband, parasitic stopband and identified the causes of problems.6 Based on the comparison between actual performance and theoretical analysis, it identified the inadequacy of existing programs, and noted the design ideas and implementation methods which could further improve the performance of ultra-wideband filter.