A novel parallel coupled-line microstrip bandpass filter with multiple transmission zeros for spurious suppression

A novel parallel coupled-line microstrip bandpass filter with multiple transmission zeros is proposed. This filter exhibits low in-band insertion loss and good stopband rejection with the spurious passbands pushed to the higher frequencies. Specifically, a microstrip filter, with the center frequency designed at f₀ = 2GHz, having 16.3% 3-dB bandwidth, and a rejection band extended up to 6 f₀, is implemented and carefully examined.