In this paper, a new microstrip model design of bandpass filter is
proposed. Open stubs are applied to the band pass filter to refine the skirt
selectivity on both sides of the upper and lower frequency band. Two
attenuation poles are produced by this new structure. The upper band pole is
introduced by the hairpin-comb structure. The lower band pole is introduced
by the tapped open stubs. We fabricated a new structure using milling
machine at the Lab in University of North Texas (UNT). Two attenuation
poles are realized at the upper band and the lower band respectively, one at
1.71GHz and one at 1.93GHz. Sharp roll-off on both sides of the pass band is
obtained. Measured results show good selectivity at both upper and lower