A suspended stripline dual-band filter using inter-digitally coupled resonator pairs

This paper presents a design of suspended stripline dual-band filter, in which, inter-digitally coupled resonator pairs act as dual-mode resonators to realize the two passbands. Parallel coupling is adopted between adjacent dual-mode resonators and the input/output couplings are realized using tapped lines of certain height. A prototype dual-band filter with two bands located at 2.4 and 5.2GHz is designed and fabricated. Advantages of low insertion loss and high in-between isolation are observed by the measurement. To adjust the ratio of bandwidths, an improved dual-band coupling schematic is given with simulated results presented.