Novel Compact Dual Bandstop Filter Using Radial Stub

This work presents a novel compact dual bandstop filter (DBSF) using planar modified radial stub connected in shunt with 50 Ω microstrip line. The simulation results of the DBSF filter demonstrates good dual wideband bandstop filter (BSF) characteristics with 3 dB stopband fractional bandwidth of 65.42 % and 34.23 % at f1 = 2.4 GHz and f2 = 5.2 GHz resonating frequencies respectively. The insertion loss and return loss of more than 30 dB and less than 1 dB respectively at both resonating frequencies in the stop bands is also depicted. The proposed filter offers an upper passband response extended up to 10 GHz and a very compact size of 13.4 × 13.4 mm = 179.56 mm2. To validate the feasibility of the proposed design, few bandstop filters are analyzed, designed and the final proposed structure is fabricated and tested. The experimental results agree well with the simulation results.