Direct synthesis method of multi-passband filters

A direct synthesis method of microwave multi-passband filters is discussed in this paper. Different from the classical synthesis technology, this method does not require the frequency transformation or polynomial optimization, directly and separately synthesizes generalized Chebyshev characteristic function of each passband in band-pass domain, the final multiband filtering function obtained, which apply to wideband condition and bandwidth of each passband can be easily controlled. The admittance matrix derived from the filtering function is physically meaningful and examples show a good agreement.