Compact UWB bandpass filter with two notch bands based on folded SIR

An ultra-wideband (UWB) bandpass filter (BPF) with two sharply rejected notch bands based on a folded stepped impedance resonator (SIR) is investigated. The proposed UWB BPF comprises four folded shunt quarter-wavelength short-circuited stubs, and two coupled SIRs with metallized via holes to ground. The SIRs are studied and employed to generate the desired two notched bands. The predicted results are compared with measured data and good agreement is reported.