Abstract: A dielectric filter includes resonator electrodes, an inter-stage coupling capacitor electrode, and an input/output coupling capacitor electrode on dielectric substrates, respectively. The resonator electrodes are electro-magnetically coupled to each other to form a tri-plate structure, are made of a metallic foil embedded in a resonator dielectric substrate. Another dielectric filter includes an upper shield electrode dielectric substrate, an inter-stage coupling capacitor dielectric substrate, a resonator dielectric substrate, and an input/output coupling capacitor dielectric substrate which are made of a composite dielectric material including a high-dielectric-constant material and a low-dielectric-constant material. The above described arrangement provides the dielectric filter with an improved Q factor of a resonator, a low loss, and a high attenuation.

Abstract: A dielectric filter, has

Abstract: A dielectric filter including a plurality of resonators, and at least one transmission line provided among said plurality of resonators. A band rejection characteristic is formed around a resonance frequency of the resonator, and a line length of the transmission line is shorter than ¼ of a wavelength corresponding to the resonance frequency of the resonator.

Abstract: There is provided a dielectric resonator including a pair of dielectric substrates opposed to each other and resonator electrodes disposed between the pair of dielectric substrate, wherein the resonator electrodes are disposed so as to be brought into contact with major surfaces of the pair of dielectric substrates, and a bonding layer is disposed around the resonator electrodes so as to bond the pair of dielectric substrates. The pair of dielectric substrates have been in advance sintered at sufficiently high temperature which is a dielectric having an fQ value at 1 GHz in the range of 3×103 to 1×105, then achieve a high Q value as a filter. The pair of the substrates are provided with the surface roughness of a range of 0.1 to 2.0 &mgr;m, and flatness of 10 &mgr;m or less between both ends thereof to bring the resonant electrodes in close contact with the surfaces of the substrate.

Abstract: The present invention comprises baluns 2a, 2b which convert balanced line signals and unbalanced line signals mutually, and filters 3a, 3b which are electrically connected to the baluns 2a, 2b and pass or attenuate the predetermined frequency bands. Electrode layers 15a-22a, 25a, 41, 42, 43 which compose the electrode patterns of the baluns 2a, 2b and the filters 3a, 3b, and the dielectric layers 30-39 are integrally stacked.

Abstract: An antenna duplexer has

Abstract: An antenna device comprising a plurality of directional antennas which are aligned on the same axis in one direction and which are also arranged in a manner that the main radiation directions of the plurality of directional antennas deviate from each other in a direction orthogonal to the direction. Hence, a drop in directivity due to the array factor can be prevented and radiation characteristics in the plane orthogonal to the direction is expanded.

Abstract: A dielectric filter, has