Interdigital band pass filters for duplexer realization for LTE band 28

This Paper presents the design of interdigital filters for the application of duplexer. The Design is Based on the coupling between the micro strip resonators of Quarter Wavelength Long. The designed filters are of seventh order Chebyshev type with a passband ripple of 0.2dB and FBWs of 6.2% and 5.7%. The structure is simulated in the electromagnetic simulation tool such as ADS. The results achieved are of insertion loss S(2,1) around 2dB, Return Loss S(1,1) is of around 17dB and the stop band attenuation of 30dB. The Alumina substrate with an height of 1.27mm and Dielectric Constant of 9.8 is used to reduce the size of the filters. The Designed filters can be used for the Development of Duplexer by increasing the Stopband attenuation to more than 50dB.