Kwang Chul Son

In this article, a microstrip wideband bandstop filter (W‐BSF) with a stepped impedance resonator (SIR)‐based interdigital capacitor (IDC) is proposed. By using an SIR‐based symmetric IDC, a wide rejection of bandwidth of 4.27 GHz at the center frequency of 5.85 GHz can be achieved. The insertion loss ( S 21 ) and return loss ( S 11 ) were 17.89 dB and 0.22 dB at 5.85 GHz, respectively, in the measurement results, which also verified that the bandwidth can be widely tuned by increasing the length, d from the main transmission line to the SIR‐based symmetric IDC section. As a result, we achieved practically applicable simulated and measured S ‐parameter responses. The overall dimension of the optimized W‐BSF was (13.80 × 10.98) mm 2 .