Abstract: A stripline resonator is constructed of a dielectric plate having a ground electrode formed on a side surface thereof, an open-ended .lambda./2 long stripline arranged on a top surface of the dielectric plate, an input terminal to which signals are inputted, said input terminal is connected to one end of the open-ended .lambda./2 long stripline, a first reactance element connected either in series or in parallel between the input terminal and the open-ended .lambda./2 long stripline, and a second reactance element connected at one end thereof to an opposite end of the open-ended .lambda./2 long stripline and at an opposite end to a ground electrode.

Abstract: An LC-type dielectric filter includes a plurality of substrate layers which are arranged in a stack and laminated to form a multi-layer substrate. Strip line resonators are provided on some of the substrate layers. The filter has a plurality of terminals, which are connected to resonators. The terminals are also capacitively or inductively coupled to each other. At least one grounding layer is included in the stack for electrically isolating the resonators. Coupling between the resonators can be obtained by forming a plurality of resonators close to one another on the same substrate layer. Further, a duplexer can be made from filters of this type. The duplexer may include a matching circuit and a power amplifier for RF transmission.