Dual-Band Bandpass Filter using Defected Microstrip Structure (DMS) for WIMAX Applications

Abstract

This paper presents dual-band bandpass filter using defected microstrip structure (DMS). The two DMSs was integrated with short circuit stub bandpass filter to produce high attenuation and good selectivity between dual-bandpass. The DMS was designed at 3 GHz with a fractional bandwidth of about 20% and the attenuation is better than 70 dB. The group delay in the passband of dual-band was lower than 1.2 and 1.5 ns respectively. The design was simulated and fabricated on a Roger Duroid RO4350 with a thickness of 0.508 mm and dielectric constant, εr of 3.48. This type of filter is useful in any RF/microwave communication systems to enabling pre-selection of more than one band from interferers. While maintaining its excellent performance, the overall physical and cost reduction can also be achieved using this technique.