Highly Selective Triple Band Filter Using Stub Loaded Folded Step Impedance Resonator

A triple pass band filter with central pass band frequencies 2.4, 5.2 and 8.6 GHz is proposed in this article for the application in Wireless Local Area Network (WLAN) and Satellite Communication. The impedance ratio of a pair of Folded Step Impedance Resonator and the positioning of a pair of open stubs are accurately adjusted to achieve these pass band frequencies. Apart from these another pair of open stubs are used to produce multiple Transmission zeros in between the pass bands. The simulation of the proposed filter is done with HFSS13 software and the measured frequency response of the fabricated prototype achieved high correlation with the simulation results. The miniaturized size of the filter is (20.7mm x 22mm) and the in-band Insertion Losses are 0.8, 1.0 and 0.9 dB.