Two Novel Classes of Band-Reject Filters Realizing Broad Upper Pass Bandwidth—Synthesis and Design

The synthesis and design of two novel classes of band-reject filters capable of realizing broad upper pass bandwidth is presented in this paper. The proposed filters comprise novel coupled-line network sections whose equivalent distributed circuits are also derived in this work for the first time. By virtue of the circuit-oriented synthesis approach pursued in this study, the new filters comprise asymmetrically coupled stepped-impedance resonators. Numerical examples are presented demonstrating the step-by step synthesis and design of the two new classes of band-reject filters performing a particular electrical specification. Finally, one of the two synthesized band-reject filters is fabricated and characterized leading to a measured frequency performance exhibiting a first spurious stopband centered at five times the center frequency of the fundamental stopband.