Analysis And Design Of Band-pass Filter Using Coupled Lines Micro-strips

Abstract

The project aims to design and analyze an RF band-pass filter between 5.1 GHz to 5.3 GHz using coupled line micro strips. There are two main methods of designing RF filters i.e image parameter method and insertion loss method. The insertion loss method is used for designing the filter as it provides a high degree of control over the pass band and stop band amplitude and phase characteristics. In order to synthesize the band-pass filter, a low-pass filter was designed first. The circuit consisted of lumped components that were transformed into distributed element i.e micro strip by using Richard’s transformation and Kuroda identities. The cut off frequency of low-pass filter was 5 GHz but the insertion loss was larger than the acceptable value so the circuit was tuned to overcome the problem. For band-pass filter Richard’s transforms and Kuroda identities are not applicable because lumped components can be in series and in shunt at the same time. Impedance and admittance inverters are used for designing of band–pass filter. The values of filter components were taken and the even and odd mode impedances were calculated for the required frequency and order. The simulation results are very much closed to the required ones so the layout of the circuit is converted to hardware design.