Multiband Bandstop Filter using an I-Stub-Loaded Meandered Defected Microstrip Structure

Abstract

This paper presents a compact multiband bandstop filter (BSF) that utilizes an I-stub embedded within a meandered defected microstrip structure (MDMS). The proposed design for obtaining a single stopband is analyzed by using a transmission line network model. On the basis of the single stopband structure, we designed and fabricated a dual- and tri-band bandstop filters operating at 2.5/6.78 GHz and 1.98/5.60/7.78 GHz, respectively, thereby exploring the concept of generating as many stopbands by simply adding the same number of I-stubs. The proposed filter also features the possibility of tuning the resonant frequencies by varying the width of the I-stubs.