Bandpass filters using multilayered microstrip structures

Abstract

The behaviour of the microstrip line structures at the different layers of the substrates, offers an area of research with growing interest. This filter is developed by a conventional three-pole open circuited stub microstrip lowpass filter structure, which shows abrupt change in its behaviour when incorporated with more than one layers of substrates. The additional substrate has wide gap microstip edge coupled lines. These structures provide additional overlapped coupling and cross coupling between two layers, except for the coupling effect on the same layer. The designed filter demonstrates the frequency characteristics with central frequency f0 of 2.28 GHz, insertion loss of 0.2 dB and 35 % FBW.