Described is a bandpass filter comprising a multi-layered body, a first resonator conductor formed on a first layer of the body and a second resonator conductor formed on a second, tower layer of the body. The first resonator conductor and the second resonator conductor comprise a first coupling area formed by only a partial overlap of the first resonator conductor and the second resonator conductor. A length of each said resonator conductor is in the range of λ.sub.g/3 to λ.sub.g/5, where λ.sub.g. is a center wavelength of the bandpass filter passband.

A filter includes first and second resonators and first and second stub resonators. Each of the first and second resonators includes a first conductor part and a second conductor part electrically connected to the first conductor part and having an impedance smaller than an impedance of the first conductor part. The first stub resonator is electrically connected to the first conductor part of the first resonator. The second stub resonator is electrically connected to the first conductor part of the second resonator. The shape of the first stub resonator and the shape of the second stub resonator are different from each other.

A dielectric filter includes: a resonator body formed of dielectric material; surrounding dielectric portion present around the resonator body and formed of dielectric material having a relative permittivity lower than the dielectric material used to form the resonator body; and an input/output conductor portion formed of a conductor and configured to perform at least one supply of an electromagnetic wave to the resonator body and reception of an electromagnetic wave from the resonator body. The resonator body has a first end face and a second end face located at opposite ends in a first direction. The input/output conductor portion is located either at least part of the input/output conductor portion is contained in a space formed by shifting a virtual plane corresponding to the first end face in the first direction away from the second end face, or the input/output conductor portion is in contact with the space.

The invention provides a bandpass filter, comprising: a substrate with a plurality of dielectric layers; a plurality of resonators; and a plurality of ground layers each having one slot arranged on; wherein the plurality of resonators are arrayed vertically each on respective one of the plurality of dielectric layers alternately without any of offsets, and each of the plurality of ground layers is between adjacent dielectric layers. Adjacent slots are arranged in opposite sides of the ground layers. The invention also provides a method of fabricating the bandpass filter.

A filter includes: a first resonator and a second resonator; a first strip-shaped conductor which is provided on a dielectric layer provided on a surface of a first wide wall of the first resonator; a first conductor pin which is electrically connected to a first end of the first strip-shaped conductor; a second strip-shaped conductor which is provided on a dielectric layer provided on a surface of a first wide wall of the second resonator; and a second conductor pin which is electrically connected to a first end of the second strip-shaped conductor.

The dielectric resonator includes a sealing cover, a dielectric resonant column, a metal cavity, and an electrically-conductive elastic structure body. The dielectric resonant column is located within the metal cavity, wherein the sealing cover is connected to an upper surface of the dielectric resonant column. The sealing cover is located at the upper end face of the metal cavity and is configured to seal the metal cavity. The metal cavity is provided with a groove at the bottom. The electrically-conductive elastic structure body is located within the groove and is configured to support the dielectric resonant column. The depth of the groove causes a lower surface of the dielectric resonant column to be lower than an inner bottom surface of the metal cavity after the sealing cover seals the metal cavity. A lower end face of the dielectric resonant column is in contact with the electrically-conductive elastic structure body.

Provided is a dual-band resonator which can be downsized further than conventional ones. A dual-band resonator is provided with a first conductor and a second conductor. The first conductor is configured to be folded at a first folding part at the center so that both extensions are in a prescribed direction and adjacent to one another with a prescribed space therebetween, wherein a conductor part closer to one end side than the first folding part and a conductor part closer to the other end side than the first folding part are further folded at second folding parts between the one end and the first folding part and between the other end and the first folding part, respectively, in a direction in which the one end and the other end are apart from each other. The second conductor extends in a prescribed direction contiguously to the first folding part of the first conductor. The first conductor constitutes a half-wavelength resonator, and odd-mode resonance occurs in the first conductor. The first conductor and the second conductor constitute a half-wavelength resonator, and even-mode resonance occurs in the first conductor and the second conductor.

A band pass filter (1) includes two resonators (8) and (10) including respectively linear conductors (9) and (11) disposed inside a dielectric substrate (2), and a pair of input-output lines (13) and (14) to which the two resonators (8) and (10) are connected in parallel. Both ends of the linear conductor (9) of the resonator (8) are left open. The resonator (10) includes vias (12A) and (12B) through which both ends of the linear conductor (11) of the resonator (10) are connected to a ground conductor (6) on a first surface (2A) of the dielectric substrate (2). The pair of input-output lines (13) and (14) include respectively vias (15A) and (15B) for connection to a ground conductor (7) that is disposed on a second surface (2B) of the dielectric substrate (2).

A ring resonator based T-shaped duplexer for use in communication systems, the T-shaped duplexer comprising a T-shaped microstrip duplexer body having a first rectangular-shaped body section and a second rectangular-shaped body section that extends from the first-rectangular shaped section in a perpendicular position relative to the first rectangular-shaped section, three connection ports including a first connection port disposed at an open end of the second rectangular-shaped body section, a second connection port disposed at one end of the first rectangular-shaped body section, and a third connection port disposed at another end of the first rectangular-shaped body section, and two bandpass filters, each bandpass filter comprising a ring resonator structure having a circular shape, an outer edge of the ring resonator structure being connected to the first rectangular-shaped body section of the T-shaped microstrip duplexer body, wherein each of the two bandpass filters creates an Electromagnetically Induced Transparency (EIT) window within a frequency absorption region of the bandpass filter to allow a signal to pass at a pre-tuned frequency band.

A ring resonator based T-shaped duplexer for use in communication systems, the T-shaped duplexer comprising a T-shaped microstrip duplexer body having a first rectangular-shaped body section and a second rectangular-shaped body section that extends from the first-rectangular shaped section in a perpendicular position relative to the first rectangular-shaped section, three connection ports including a first connection port disposed at an open end of the second rectangular-shaped body section, a second connection port disposed at one end of the first rectangular-shaped body section, and a third connection port disposed at another end of the first rectangular-shaped body section, and two bandpass filters, each bandpass filter comprising a ring resonator structure having a circular shape, an outer edge of the ring resonator structure being connected to the first rectangular-shaped body section of the T-shaped microstrip duplexer body, wherein each of the two bandpass filters creates an Electromagnetically Induced Transparency (EIT) window within a frequency absorption region of the bandpass filter to allow a signal to pass at a pre-tuned frequency band.