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Compact dual-band bandpass filter using asymmetric stepped impedance stub loaded multimode resonator

Published online by Cambridge University Press:  02 July 2015

Manimala Pal*
Radio Engineering and Antenna Laboratory, Department of Electronics and Communication Engineering, NFET, NSHM Knowledge Campus Durgapur, Durgapur-713212, India
Rowdra Ghatak
Microwave and Antenna Research Laboratory, Electronics and Communication Engineering Department, National Institute of Technology Durgapur, Durgapur-713209, West Bengal, India
Pankaj Sarkar
Electronics and Communication Engineering Department, School of Technology, North Eastern Hill University, Shillong-793022, Meghalaya, India
Corresponding author: M. Pal Email:


This paper presents, a dual-band bandpass filter using asymmetric stepped impedance stub loaded open loop resonator (OLR) for WLAN and WiMAX application. The outer OLR is realized to operate at lower passband of 2.45 GHz which is directly coupled to input and output ports whereas the asymmetric stepped impedance stub that loads the outer resonator contributes to 3.5 GHz passband. The introduction of asymmetric stepped impedance stub provides further control of improving the upper passband edge selectivity of second passband and in shifting the spurious modes away from second band thereby contributing to the wide upper stopband. The insertion loss is within 1.5 dB for each passband with 10 dB passband bandwidth of 250 MHz at both bands. A stopband up to 10 GHz is also obtained. A prototype is developed and the s-parameters obtained from electromagnetic simulation, equivalent transmission line model and measurement are in close agreement. The overall dimension of the filter is 25.45 × 15.89 mm2 which renders it a compact size.

Research Papers
Copyright © Cambridge University Press and the European Microwave Association 2015 

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