Stripline resonator filter including cooperative conducting cap and film

Abstract

The present invention relates to a filter employed in a radio communication apparatus and has as an object to prevent characteristics of the filter from degradation by increasing unloaded Q of strip line resonators of the filter. For achieving the above object, the invention provides a filter which comprises a substrate (4) having first and second strip lines (5), (6) formed on a top surface and mutually coupled through an electromagnetic field and an earth pattern (2) on a bottom surface, respectively, a dielectric layer (8) laminated on the top surface of the substrate and having capacitor patterns (9), (10) formed on a top surface thereof in opposition to the aforementioned first and second strip lines (5), (6), and a metal cap (1) fitted over the dielectric layer (8) having an electrically conductive surface at least on one of top and bottom surfaces, and an electrically conductive film formed on a portion of an outer peripheral surface of the aforementioned substrate (4) and connected to the earth pattern (2) on the bottom surface thereof, wherein at least a portion of an outer periphery of the metal cap (1) is led downwardly toward the electrically conductive film, and the portion led downwardly is connected to the electrically conductive film.

Dependencies are inferred from the claim text.