Dielectric filter

Abstract

A dielectric filter, includes a dielectric block including a plurality of elongated sub-blocks each having a pair of longitudinally opposing end faces and an outer surface, said sub-blocks being disposed adjacent one another; a plurality of longitudinally extending through-holes, at least one through-hole being formed between each corresponding pair of opposing end faces of the respective sub-blocks; a plurality of inner conductors, one inner conductor being formed on each of the inner surfaces of said plurality of through-holes, said plurality of inner conductors each having two opposing ends; an outer conductor formed on the outer surface of said dielectric block such that (i) the outer conductor is not electrically coupled to the respective ends of the inner conductor of every other sub-block such that the ends of those inner conductors are open-circuited, and (ii) the outer conductor is electrically coupled to the respective ends of the inner conductor of the remaining sub-blocks such that the ends of those inner conductors are short-circuited; a plurality of connection conductors through which respective parts of the inner conductors located between corresponding open-circuited opposing ends are connected to said outer conductor; and an electromagnetic coupling preventing structure formed between each adjacent pair of sub-blocks and extending from one end face of each of said sub-blocks toward a central part of said sub-blocks between the two opposing end faces, wherein said dielectric filter produces a band elimination transfer function over some frequencies and a pass transfer function over other frequencies in use.