Exact Design of a New Class of Generalized Chebyshev Low-Pass Filters Using Coupled Line/Stub Sections

A method for the design of a new class of distributed low-pass filters enables exact realization of the series short-circuited transmission lines, which are normally approximated via unit elements in other filter realizations. The filters are based upon basic sections using a pair of coupled lines, which are terminated at one end in open-circuited stubs. The approach enables realization of transmission zeros at the quarter-wave frequency, hence giving improved stopband performance. A complete design theory starting from a distributed generalized Chebyshev low-pass prototype filter is presented. A design example demonstrates excellent performance in good agreement with theory.