Differential‐mode bandpass filter on microstrip line with wideband common‐mode suppression

A novel differential‐mode (DM) bandpass filter (BPF) on microstrip‐line topology with wideband common‐mode (CM) suppression is presented. The DM BPF is composed of a pair of half‐wavelength ( λ /2) uniform impedance resonators and two coupled‐line sections as feeding scheme. By installing an open‐circuited stub in the middle of the coupled‐line section, spurious CM response can be tremendously suppressed over a wide band. Thus, wideband CM suppression is realised in and beyond core DM passband. Finally, a DM BPF is designed and fabricated to support the proposed design concept.