A filter for suppressing 5G signal interference comprises a high-frequency filter circuit that uses a coil hung and disposed in a conductive isolating cavity as an inductor and that uses a combination of the conductive isolating cavity, dielectrics in the conductive isolating cavity, and the coil as a capacitor. A new-type filter circuit comprises a conductive isolating cavity, dielectrics in the conductive isolating cavity, and a coil hung and disposed in the conductive isolating cavity. The coil itself is an inductor in a high-frequency filter circuit, the coil and the conductive isolating cavity further form two conductors close to each other, and air media in relatively small space between the two conductors form non-conductive insulated media, to jointly form a new-type capacitor. That is, the coil in the high-frequency filter circuit is both an inductor and a conductor that forms a capacitor.