Design And Research Of Novel Microstrip Bandstop Filters

Bandstop filter is a microwave device that let signal out of a frequency band go through and reject this frequency band.Although so far there have been many domestic and foreign experts and scholars made research on bandstop filter,there are some problems. For example,to design a microwave filter whose bandwidth is wide enough, the same time other indicators are excellent. The main content of this paper is organized as follows:1. First, introduce the fundamental design principles of bandstop filter.As a starting point,introduce the lowpass prototype filter.Then, realize the lowpass prototype circuit by lumped parameter circuit, then get bandstop filter design goals required through their relationship transformation.2. Based on the theory, study the bandstop filter by using ADS.Using a lowpass filter and a highpass filter in parallel to design a bandstop filter.Center frequency can be obtained according to the desired cutoff frequency of the highpass filter and the lowpass filter. This method widening microstrip bandstop filter stop band bandwidth and improve the filter characteristics of microstrip bandstop filter.3. Try to use suspended microstrip line method and method used in ADS to design a bandstop filter. Using improved annular units to design a bandstop filter which the relative bandwidth is 58%.