Design of Ultra Wideband Bandpass Dual Band FilterUsing Defected Ground Structures

This paper presents a novel approach fordesigning compact and ultra wideband filter withindependently controlled central frequencies. The structureconsists of a microstrip line and two defected ground structurecells that are imbedded together. Each of the cells results inrespective passband, outer cell for the first passband and innerone for the second passband. By changing dimensions of theresonators the central frequency of two passbands can beindependently regulated in a wide range. Several attenuationpolls in the stopband are realized that improve the isolationbetween two passbands. A 1.8GHz, 3.3GHz dual band filter isdesigned and simulated with fractional bandwidth of 43% and15%.