Triple band bandpass filter with cascade tri section stepped impedance resonator

In this paper, triple band bandpass filter (BPF) using cascade tri section stepped impedance resonator (TSSIR) which can operate at 900 MHz, 1800 MHz and 2600 MHz simultaneously, is proposed, designed, fabricated and evaluated. The cascade TSSIR BPF is proposed as enhancement of the TSSIR in order to improve the stopband rejection response of the TSSIR. The implementation of the cascade TSSIR is using two TSSIRs which are coupling each other in the third resonator and the input and output ports are connected to the first resonator. Design and simulation of the proposed BPF are using Advanced Design System (ADS). The proposed BPF using cascade TSSIR is fabricated on the substrate FR4 with dielectric permittivity is 4.3, the substrate thickness is 1.6 mm, and loss tangent is 0.0017. The performance parameters of the proposed BPF are characterized by insertion loss, return loss, voltage standing wave ratio (VSWR), and group delay. The performances of the simulated results are compared to that of the fabricated results of the proposed BPF. It is shown from the results that the performance of both simulated and fabricated results are satisfied to design specification and close agreement with each other.