BAND-PASS FILTER FOR ULTRA-HIGH FREQUENCY

摘要

PURPOSE:To improve attenuation characteristics over a wide band by using >=5 stages of optional BPFs by using a simple branching circuit by coupling the 1st and 4th stages of resonators by the branching circuit. CONSTITUTION:Between an input terminal 601 and an output terminal 602, coupling circuits 608-613 for BPFs are connected and between the connections points between respective coupling circuits and the earth, resonators 603-607 are connected. Then, the 1st stage of the resonator 603 and the 4th stage of the resonator 606 are coupled mutually by a branching circuit (subordinate transmission line) 614. The coupling circuits 608-613 are coupled by capacitors and, the branching circuit 614 is composed of two coupling capacitors and a coaxial cable for phase adjustment having 3/4-wavelength cable length at a center frequency; all coupling capacitors and the cable are formed one printed substrate.