Patent ID: 6111482
Filing Date: 2000-08-29
Classification: H01P

Abstract:
A communication apparatus comprising:a variable-frequency bandstop filter, said bandstop filter having:an input terminal, an output terminal, and a voltage control terminal;a plurality of dielectric resonators electrically connected in a circuit which interconnects said input terminal and said output terminal;a variable-capacitance diode connected to said voltage-control terminal whose capacitance can be electrically changed by a control signal from said voltage control terminal;a first capacitor electrically connected in series with said variable capacitance diode on the cathode side of said variable-capacitance diode;at least one second capacitor electrically connected in parallel with the series circuit of said variable-capacitance diode and said first capacitor; andsaid parallel circuit comprising said variable-capacitance diode, said first capacitor and said second capacitor is electrically connected in series with one of said plurality of dielectric resonators; andsaid series circuit which comprises said parallel circuit and said one of said plurality of dielectric resonators provides a trapping circuit of said bandstop filter, thereby providing an attenuation pole of said bandstop filter.