Abstract: A band pass filter is constituted of a dielectric block 2 having through holes 5 formed from one surface to the opposite surface and a single layered dielectric plate 3 joined to the dielectric block 2 such that the back surface thereof faces the one surface of the dielectric block 2.

Abstract: In a dielectric filter, from the top surface to the bottom surface of a substantially rectangular dielectric block, inner-conductor holes are formed. On the inner surfaces of the inner-conductor holes, inner conductors are formed except where non-conductor portions are formed in proximity to one of the top and bottom surfaces, in which the apertures of the inner-conductor holes are formed. On the outer surface of the dielectric block, an outer conductor is formed substantially over the entire outer surface, and input and output electrodes isolated from the outer conductor are coupled with the non-conductor portions in the respective inner-conductor holes at the ends of the dielectric block in the direction of array of the inner-conductor holes.

Abstract: The present invention provides a small dielectric filter suitable for use in a high frequency band equal to or higher than 3 GHz. an input/output electrode made up of island type of conductive film is formed on one surface of said dielectric located on each end portion; in each of said dielectrics located on each end respectively, an earth electrode is formed on almost of all remaining area of said surface so as to be isolated from said input/output electrode and is also formed on all of the other surfaces with an exception of connecting surfaces; in an intermediate dielectric, an earth electrode is formed on all surfaces other than the connecting surface; and a conductive film connected to the earth electrode is formed on a part of at least one of the connecting surfaces of the dielectrics to be connected. Three or more elements of resonators may be integrally formed on a dielectric block, and, in that case, a through-hole is formed between the resonators.

Abstract: A duplexing filter suitable for use in a mobile communication system. The filter has a core of dielectric material with several through holes that define resonators. The core has metallized surfaces except for the top surface. Several metallized resonator pads surround each of the through holes on the top surface. A metallized serpentine region extends from one or more of the resonator pads toward a side surface of the core. The metallized serpentine region causes attenuation of a third harmonic frequency.

Abstract: The present invention is a preferred monoblock ceramic bandpass duplexer filter. The preferred filter has at least three I/O pads. One of the pads is coupled to an antenna, another is connected to a transmission circuit and the last pad is connected to a receive circuit. The filter is comprised of two sections: a transmission section and a receive section. The transmission and receive sections include resonators disposed on respective sides of the antenna pad. A first alternative signal path is disposed adjacent the ends of the transmission resonators. A second alternative signal path is disposed adjacent to the ends of the receive resonators. Each alternative signal path couples adjacent and non-adjacent resonators. A further feature of the filter of the present invention includes a shunt zero resonator for the transmission section. To the contrary, the present invention allows the elimination of a shunt zero resonator for the receive section of the filter.

Abstract: A small-sized low-loss dielectric resonator, dielectric filter, and dielectric duplexer, and a communication device using such an element. Through-holes are formed in a dielectric block. The inner surface of each through-hole is covered with a thin-film multilayer electrode consisting of an outermost conductive layer and a multilayer region including thin-film conductive layers and thin-film dielectric layers. An outer conductor having a similar thin-film multilayer electrode structure is formed on the outer surface of the dielectric block. An outer conductor in the form of a single-layer electrode is formed on a short-circuited end face of the dielectric block thereby connecting together the thin-film conductive layers of the inner and outer conductors.

Abstract: A small dielectric filter suitable for use in a high frequency band equal to or higher than 3 GHz. An input/output electrode made up of island type of conductive film is formed on one surface of the dielectric located on each end portion. In each of the dielectrics located on each end respectively, an earth electrode is formed on almost all of the remaining area of the one surface so as to be isolated from the input/output electrode and is also formed on all of the other surfaces with an exception of connecting surfaces. In an intermediate dielectric, an earth electrode is formed on all surfaces other than the connecting surface, and a conductive film connected to the earth electrode is formed on a part of at least one of the connecting surfaces of the dielectrics to be connected. Three or more elements of resonators may be integrally formed on a dielectric block, and, in that case, a through-hole is formed between the resonators.

Abstract: A filter and a method of making a filter to remove unwanted frequency harmonics associated with current filters. The filter is made up of resonators, such that the filter resonates a design frequency. Whereby, at least two resonators are coupled together between an input and an output and at least one of the resonators is of a different design from other resonators, such that the resonator of a different design resonates the same design frequency as the other resonators and resonates different higher order harmonic frequencies than the other resonators. The present invention also provides methods of improving skirt response for a filter, as well as other response properties of the filter.

Abstract: The invention relates to a ceramic microwave filter having an insertion loss characteristic curve with an improved steepness. At least two resonators are provided in a one-piece ceramic body and coupling structures are assigned to the resonators for capacitively coupling the ceramic filter to an external RF circuit. At least one counter-oscillator is led in parallel with the resonators in the ceramic body.

Abstract: A plurality of resonators 50 are formed in a dielectric porcelain block 42, wherein each of the resonators 50 is formed by coating an interior surface of a through section with an interior conductor 54, thus constituting a dielectric filter 41. On a side surface 44 of the dielectric block 42 perpendicular to an open end face 43 having the through sections formed therein, there are formed protrusions 45 having a height L lower than that of the through sections. Terminal electrodes 60a and 60b are defined with the protrusions 45 taken as a boundary between the terminal electrodes 60a and 60b, and isolated from an exterior conductor 62.

Abstract: A high frequency ceramic compact includes Al, Ti and Mn as metallic elements and contains substantially no Al2TiO5 phase as determined by X-ray diffraction analysis and is obtained by firing at about 1310° C. or lower. A preferred high frequency ceramic compact is represented by the following formula and has a Q-value at 10 GHz of 10,000 or more: (100−x−y)AlO3/2−xTiO2−yMnO, wherein x and y are % by mole and x and y satisfy the following conditions: 3.0≦x≦9.0; and 0.1≦y≦1.0. These high frequency ceramic compacts have a relative dielectric constant of 20 or less, a Q-value at 10 GHz of 10,000 or more, and can optionally control the temperature coefficient of resonant frequency around 0 ppm/° C.

Abstract: In a cavity body, a conductor rod is provided with least one end thereof being electrically connected to the cavity. A dielectric core is disposed in the cavity and the conductor rod extends through a hole in the dielectric core. With this structure, the cavity and the conductor rod constitute a resonator which operates in the quasi-TEM mode of a re-entrant cylindrical cavity resonator. The cavity and the dielectric core constitute a resonator which operates in the quasi-TM mode.

Abstract: The invention provides a dielectric filter, comprising: a dielectric block having a first end face and a second end face and side faces extending therebetween; a plurality of resonator holes and at least one external coupling hole respectively passing through both end faces; inner conductors provided on inner faces of the resonator holes and the external coupling holes; an external conductor provided on the outer faces of the dielectric block; concavities provided in formation regions of the external coupling holes on the first and the second end face and in the short-circuiting regions of the resonator holes; and the external conductor being removed except from the portions of the concavities in the first end face and the second end face, thereby forming open faces of the resonator holes on the first end face and the second end face.

Abstract: A dielectric filter in which many attenuation poles can be generated, including attenuation poles generated by tap coupling, so that arbitrary passing characteristics and attenuation characteristics can be obtained. In this filter, inside a dielectric block there are formed through-holes having stepped structures in which inner conductors are disposed on the inner surfaces of the holes to capacitively couple the resonators. There are also formed lateral holes having conductive films disposed on the inner surfaces of the holes. The lateral holes are connected to input/output terminals in predetermined positions of the inner conductors. Further, terminal electrodes may be disposed adjacent to predetermined positions of the inner conductors. With this arrangement, attenuation poles are generated by both distributed constant resonator coupling and tap coupling on the low frequency side and/or the high frequency side of a pass band.

Abstract: Plural inner conductor formation holes 2a, 2b, and 2c having inner conductors formed on the inner walls thereof are arranged inside of a dielectric block 1, and an outer conductor 3 is formed so as to cover the outer surface of the dielectric block 1. The openings of the respective inner conductor formation holes 2a to 2c on the open end side have round hole shapes having substantially the same diameters. The cross-sections of a part of the inner conductor formation holes on the short-circuit end side have angular shapes.

Abstract: The present invention relates to a dielectric device that is suitable for miniaturization and height reduction and is surface-mountable. In a resonator unit Q1, a first hole 41 is provided to a dielectric substarate 1, extends from a surface 21 toward a surface 22 opposite thereto, opens in the surface 21, and has a first internal conductor 61 in the interior. A second hole 51 is provided to the dielectric substarate 1, opens in a surface 23 adjacent to the surface 21, extends from the surface 23 toward a surface 24 opposite thereto, and is connected with the first hole 41 in the interior of the dielectric substarate 1. The second hole 51 has a second internal conductor 81 in the interior, and the second internal conductor 81 is connected to the first internal conductor 61 in the interior of the dielectric substarate 1.

Abstract: In a resonator having a dielectric member and an electrode formed on the dielectric member, a displacement area (D area) having a high vertical electric field component, and a short or steady area (S area) having a vertical electric field component of zero or close to zero are provided in an interface between the dielectric member and the electrode. A single-layer conductive film divided into portions is formed in the D area or on the side surfaces of the dielectric member, and a multilayer thin-film electrode is formed in the S area or on the end faces of the dielectric member. Conductive thin films of the multilayer thin-film electrode are alternately connected to the single-layer conductive film portions. In-phase currents having the same amplitude flow to the conductive thin films of the multilayer thin-film electrode in the S area in radial direction with respect to the axis of symmetry, thus achieving low-loss operation of the multilayer thin-film electrode in the S area.

Abstract: In order to provide a dielectric resonator filter which can be reduced in dimension, can be reduced in height, and can be surface-mounted, in a dielectric resonator filter including a rectangular-parallelopiped or polygonal-pole-like metal cavity in which at least one dielectric resonator is arranged between one pair of input/output probes, the input/output probes are attached to corner portions of the rectangular-parallelopiped metal cavity.

Abstract: A signal separator and bandpass filter that use plates with posts. The signal separator uses two bandpass filters to separate two signals of different carrier frequencies from one another. The bandpass filters each have a transmission line with the metallic plates disposed along its length. The number of plates and the distances between adjacent plates determine the bandwidth and the rejection capability of the filter.

Abstract: In a dielectric block, an array of three excitation holes, in each of which one opening is a short-circuited end and the other opening is an open-circuited end, are disposed so as to be interdigitally coupled and balanced input-output terminals are provided at the opening of the excitation holes at both ends of the array. A resonator hole is provided so as to be coupled to one excitation hole of the excitation holes at either end of the array. Thus, a compact dielectric filter with balanced input-output terminals is constructed.

Abstract: A dielectric filter includes a dielectric block having inner-conductor-formed holes extending from a first face of the dielectric block to a second face opposed to the first face. Inner conductors are formed inside the inner-conductor-formed holes such that both ends of the inner-conductor-formed holes are open-circuited. On the exterior surface of the dielectric block, balanced input/output terminals are capacitively coupled to the open ends of the inner-conductor-formed holes. A metal cover is provided so as to cover one of the first or second face of the dielectric block. The metal cover functions as a short-circuit conductor in a spurious mode such as a TE mode other than a TEM mode, and hence the influence of the spurious mode is avoided.

Abstract: There is disclosed a dielectric filter comprising: a &lgr;/2 resonator for generating resonance of ½-wavelength at a predetermined frequency, having both ends open-circuited or short-circuited; and a pair of &lgr;/4 resonators respectively for generating resonance of ¼-wavelength at a frequency substantially equal to the predetermined frequency, each having one end open-circuited and the other end short-circuited; wherein the pair of &lgr;/4 resonators are disposed in proximity to each of both ends from the vicinity of the center of the &lgr;/2 resonator; a terminal coupling to the &lgr;/2 resonator is provided as an unbalanced terminal; and terminals coupling to the pair of &lgr;/4 resonators is used as a balanced terminal. In the above filter, the balanced-type input/output of signals can be performed without using a balun.

Abstract: A dielectric filter and a dielectric duplexer with improved out-of-band attenuation characteristics in the vicinity of the pass band without changing the pass band characteristics. Inner conductor forming holes are formed from one end face to the opposite end face of a dielectric block, and inner conductors are formed on the respective inner surfaces. An outer conductor is formed over substantially the entire outer surface of the dielectric block. On one side surface of the dielectric block, substantially parallel to the inner conductors, outer conductor gaps are provided in at least one area disposed between a pair of inner conductors, extending between the opposite end faces.

Abstract: A dielectric filter includes a dielectric block having substantially a rectangular parallelepiped shape, a plurality of internal-conductor-formed holes provided substantially parallel to one another in the dielectric block, each including an internal conductor formed on the internal surface thereof, an external conductor formed on the external surface of the dielectric block, and an input/output electrode formed on the external surface of the dielectric block.

Abstract: A dielectric filter, a dielectric duplexer, and a communication apparatus using them allow balanced input and/or output to be implemented without requiring a balun. Using a dielectric block, two &lgr;/2 resonators are individually formed using either inner-conductor-forming openings with inner conductors therein, or stripline-type conductors, both of said conductors having both ends open-circuited, and said conductors being capacitively coupled together. Terminal electrodes coupled to the vicinities of two open-circuited ends of one of the resonators are used as balanced terminals on one side, and terminal electrodes coupled to the vicinities of the two open-circuited ends of the other one of the resonators are used as balanced terminals on the other side.

Abstract: A coaxial resonator which can be electrically connected to an inductance or similar electric element easily to reduce the number of work steps for mounting and the number of parts, and a dielectric filter and a dielectric duplexer which include a resonator and which can be more compact and installed in a diminished space. The coaxial resonator includes a dielectric block having a through-bore extending through opposite end faces thereof, and a conductor layer formed over an outer peripheral surface of the block except one end face thereof and over a block inner surface defining the through-bore for causing electromagnetic waves to resonate within the dielectric block. A lead-equipped electric element has its lead inserted in and fixed in the through-bore and electrically connected to the conductor layer over the bore-defining inner surface with a braze filler metal or electrically conductive adhesive.

Abstract: Power limiting apparatus for use in a sensitive receiving system includes a gas-filled coaxial hermetically sealed line. The inner conductor includes a central region of reduced diameter connected to a metallisation layer between the inner and outer conductors. An annular gap electrically isolates the outer regions of the metallisation. When excess energy enters the device, gas breakdown occurs across the gap to produce a plasma which reflects the excess energy and prevents it travelling onward to sensitive receiver stages.

Abstract: A microstrip termination is provided with a thin film resistor connecting a transmission line to a tapered edge ground, enabling high frequency performance, such as for optical modulators. The tapered edge ground is formed with metal deposited on a substrate edge between a top surface of a substrate containing the transmission line with thin film resistor, and a bottom surface with a metal coating forming a ground plane. The tapered edge is cut at an angle in the range of 30 degrees with respect to the top surface. The microstrip termination provides a wider bandwidth of impedance matching than a standard microstrip termination.

Abstract: A dielectric duplexer has first and second filters passing two adjacent bands and is not influenced by signals in bands that are outwardly adjacent to the two passing bands. The space between small sectional area portions on short-circuit-end sides of first and second resonator holes is arranged to be relatively small, and the two resonator holes are coupled with each other according to a distributed-constant-type inductive coupling method. The space between small sectional area portions on short-circuit-end sides of fourth and fifth resonator holes is arranged to be relatively large, and the two resonator holes are coupled with each other according to a distributed-constant-type capacitive coupling method. Furthermore, the space between small sectional area portions on short-circuit-end sides of the fifth resonator hole and a sixth resonator hole is arranged to be relatively small, and the two resonator holes are coupled with each other according to a distributed-constant-type inductive coupling method.

Abstract: The invention provides a dielectric resonator device comprising a coaxial dielectric resonator 2 which comprises a dielectric block 21 having a bore 22 extending therethrough, an outer conductor layer 24 formed on an outer peripheral surface of the dielectric block 21, an inner conductor layer 23 formed on the dielectric block 21 over an inner peripheral surface thereof defining the bore 22, a short-circuiting conductor layer 25 providing a short circuit between the outer conductor layer 24 and the inner conductor layer 23, and a separated conductor layer 3 formed on the outer peripheral surface of the dielectric block 21 and electrically separated from the outer conductor layer 24. The separated conductor layer 3 is connected to the ground by a switch SW, which varies the capacity of the resonator 2 upon switching to alter the resonance frequency thereof.

Abstract: A dielectric filter and a dielectric duplexer have structures for coupling between resonators, in which a range for determining the coupling strength between the resonators can be broadened and the polarity of the coupling can be changed. In addition, a communication apparatus incorporating the dielectric filter or the dielectric duplexer can be provided. Inside a dielectric member, resonance line holes having resonance lines formed on the inner surfaces thereof are disposed. Both ends of each of the resonance line holes are open-circuited. The inner diameter of each of the resonance line holes is changed at some point in the longitudinal direction of each resonance line to form a stepped part.

Abstract: A small in-band-flat-group-delay type dielectric filter having low-loss characteristics with a small amplitude deviation and uniform-group-delay frequency characteristics is obtained, which enables broad-band characteristics to be obtained easily. The in-band-flat-group-delay type dielectric filter includes a plurality of dielectric coaxial resonators, a coupling circuit comprising a combination of reactive elements, with which the dielectric coaxial resonators are coupled to one another, and input/output terminals connected to ends of the coupling circuit. The dielectric coaxial resonators coupled to the input/output terminals are allowed to have a different characteristic impedance from that of the inter-stage dielectric coaxial resonators.

Abstract: A multimode dielectric resonator device is provided in which a dielectric core can be easily disposed in a cavity, a dielectric resonator device comprising resonators in plural stages can be obtained, and the Q0 is maintained at a high value. Dielectric cores 1b, 1c to resonate in plural modes such as TM01 &dgr;−(x−z), TE01&dgr;−y, TM01&dgr;−(x+z) or the like are supported substantially in the center of a cavity 2 by means of a support 3, in the state that the cores are substantially separated from the inner walls of the cavity 2 at a predetermined interval, respectively.

Abstract: A dielectric filter or a dielectric duplexer is provided which comprises a dielectric block in a substantially rectangular parallelepiped shape, having a pair of opposite parallel end-faces and plural sides extending between the paired opposite end-faces, one of the plural sides being a mounting face; plural resonator holes elongating through the inside of the dielectric block across the paired opposite end-faces; inner conductors provided on the inner walls of the plural resonator holes, respectively; an outer conductor provided on the outside of the dielectric block; input-output electrodes provided only on one of the paired opposite end-faces, separated from the outer conductor, and capacitance-coupled to the predetermined inner conductors, respectively; and conductive terminals for external connection, connected to the input-output electrodes, having at least portions thereof lying substantially in the same plane as the mounting face.

Abstract: Inner-conductor holes whose internal surfaces are coated with inner conductors are provided in a dielectric block. Input/output electrodes are provided on the outside of the dielectric block, coupled to the inner conductors by electrostatic capacitance. Gap portions are provided between the input/output electrodes and an outer conductor. The input/output electrodes may be formed to extend from a bottom surface (mounting surface) and onto a side surface of an external surface of the dielectric block. Filter characteristics are determined depending on a width or a depth of the gap portion on the side surface of the dielectric block.

Abstract: An improved stepped-impedance low pass filter includes a stepped-impedance low pass filter having at least one electrically conductive transmission line, such as a parallel plate, coaxial, or two-wire transmission line, having at least one inductive element and at least one capacitive element. The capacitive elements and the inductive elements are disposed in an alternating manner along a length of the transmission line. The resonance suppressed stepped-impedance low pass filter also includes at least one electrically conductive suppression element disposed along the inductive elements of the stepped-impedance low pass filter, such as centered along the inductive elements between pairs of capacitive elements. The suppression elements suppress a spurious response at at least one resonant frequency.

Abstract: The invention relates to an arrangement for fastening an inner conductor of a resonator structure and to a method for fastening an inner conductor of a resonator structure to a fastening surface structure. The arrangement comprises a fastening surface structure, which in turn comprises an edge of an opening and the opening defined by the edge, the opening being formed through the fastening surface structure. In addition, the arrangement comprises an inner conductor of a resonator structure arranged at the opening formed through the fastening surface structure, the inner conductor comprising an inner space at least on the portion of the conductor that faces the fastening surface structure, which inner space is defined by the wall of the inner conductor which extends into the opening formed through the fastening surface structure.

Abstract: A dielectric filter includes a dielectric ceramic block having the shape of a rectangular prism and including three or more through-holes formed therein in parallel. An inner conductor covers the inner surface of each of the through-holes to form the corresponding resonator. An outer conductor covers a predetermined outer surface of the dielectric ceramic block, excluding the open end surface. Input/output pads are formed on one side surface of the dielectric ceramic block such that the pads face the two end resonators. Each of the through-holes of the end resonators is provided with a counterbore. An auxiliary conductor is disposed on the open end surface to face at least one intermediate resonator between end resonators. The auxiliary conductor at least partially surrounds the intermediate resonator with an insulating gap formed therebetween, and is connected to the outer conductor on the side surface on which the input/output pads are provided.

Abstract: A dielectric block includes a plurality of plated through holes each having an inner conductor formed thereon to form respective plated through holes. At least one of the plated through holes branches into two legs at the short circuit side thereof so that the two legs are close to the short circuit side of the plated through holes adjacent thereto. This allows the resonators formed of the plated through holes to be strongly inductively coupled with each other.

Abstract: A dielectric resonant device having function of a dielectric filter and a dielectric duplexer having a desired external coupling capacitance includes a substantially rectangular-parallelepipedal dielectric block provided with inner conductive holes therein, and input-output electrodes on the outer surfaces extending from an open surface thereof. Also, a method is provided for forming input-output electrodes of the dielectric resonant device for obtaining a given external coupling capacitance, in which the input-output electrodes are formed by a cutting tool including cutting edges applied to two outer surfaces of the dielectric block along first conductive film removing lines on the two outer surfaces, extending from the open surface, and a cutting edge applied to the two outer surfaces along a second conductive film removing line connecting the first conductive film removing lines.

Abstract: A monoblock dielectric duplexer comprises resonant holes. Conductive electrodes and couplers are formed on one side of the dielectric block, whose other sides are covered with a conductive material. The conductive electrodes in a transmit-filtering portion are formed in an inter-digitating manner while the conductive electrodes in receive-filtering portion are formed to be of pad-shape. In the duplexer, capacitances of capacitors comprised of the conductive electrodes are easily and accurately set to desired values by determining the number and/or the lengths of fingers that the inter-digitating electrodes have.

Abstract: A dielectric filter comprising a dielectric block having first and second opposed surfaces with a width direction and a length direction greater than the width direction. At least three conductive through holes are arrayed in the dielectric block in the length direction. In one embodiment, a sectional shape of at least one conductive through hole located between two other conductive through holes of the at least three conductive through holes is elongated in the width direction. In another embodiment, a sectional shape of two conductive through holes on either side of a third conductive through hole of the at least three conductive through holes is elongated in the width direction. With these arrangements, the jumping coupling capacitance is controlled.

Abstract: A high frequency band pass filter using a high frequency multilayered substrate is provided that does not experience interlayer shift during lamination, requires only a small number of printings, does not shrink during firing, avoids distortion in the shape, thickness and spacing of substrate internal patterns and in the location of the internal pattern of the discrete devices after dicing, is free from burr occurrence, is excellent in dicing efficiency during fabrication, is superior in product yield and cost, and has enhanced performance.

Abstract: There is disclosed a dielectric filter, comprising: a dielectric block; a plurality of inner conductor formed holes provided in the dielectric block; inner conductors provided on the inner walls of the inner conductor formed holes; and outer conductor provided on the outer surface of the dielectric block so as to have one opening-face as an open-face of the inner conductor formed holes, and have the other opening-face thereof as a short-circuiting-face; wherein the sectional shape of the inner conductor formed holes are substantially constant in the range from the open-face to the short-circuiting-face, and a step is provided in the intermediate portion of the center axis of at least one inner conductor formed hole.

Abstract: Disclosed is a dielectric filter with improvement in inductive coupling. It comprises a filter body, input-output pad, and an inductive coupling portion. The filter body comprises a block of a dielectric material having top, bottom and grounding surfaces, and having a plurality of through-holes extending from the top to the bottom surfaces defining resonators. The surfaces are substantially covered with a conductive material with the exception that the top surface is uncoated at partial regions around the holes and that one of the grounding surfaces is uncoated at partial regions adjoining the top surface and the bottom surface. The input-output pads are formed on the grounding surface at regions adjoining the top surface, the regions being separated by the uncoated regions adjoining the top surface.

Abstract: A dielectric filter having two outside resonators, one middle resonator disposed between the two outside resonators, and a notch pattern is provided. An input pad and an output pad are formed within respective non-coated lateral areas of a lateral surface corresponding to the outside resonators, respectively. The notch pattern is formed within an expanded non-coated lateral area of the lateral surface coupled to one of the non-coated lateral areas of the lateral surface which corresponds to a third position of the lateral surface corresponding to the middle resonator and one of the outside resonators. The notch filter is extended along the lateral surface from the input pad or the output pad toward the middle position corresponding to the middle resonator. The notch filter forms an electrical capacitor between the middle resonator and the input pad or the output pad.

Abstract: The present invention provides a dielectric filter capable of increasing a designing freedom for obtaining a desired filter characteristic and capable of producing an attenuation pole in the vicinity of passing frequency band, also to provide a duplexer and communication apparatus formed by using the dielectric filter and the duplexer. In a dielectric block there are formed two through holes of rectangular cross section extending from a first end face to a predetermined depth, with the internal sizes thereof being different from each other. In this way, it is possible to enlarge the ranges obtainable by mutual capacitances on an open face side and a short circuit face side, thereby making it sure to dispose an attenuation pole in the vicinity of a passing frequency band.

Abstract: A dielectric filter includes a dielectric block and an outer conductor on outer surfaces of the dielectric block. The dielectric block has holes having inner conductors, with gaps provided by sections devoid of inner conductor. A section devoid of outer conductor is formed on an edge portion around a stray surface of the dielectric block. Accordingly, a TE-mode resonance having one quarter the wavelength in the axial length direction of the dielectric block is generated. The TE-mode resonance and a TEM-mode resonance are combined to form an attenuation pole.

Abstract: A dielectric filter includes a dielectric block having a plurality of outer surfaces including opposed top and bottom surfaces, opposed side surfaces and a mounting surface. A plurality of through holes extend between the opposed top and bottom surfaces. Respective internal electrodes are located on internal surfaces of the through holes and an outer conductor is formed on at least some of the outer surfaces. First input output electrode extends from the mounting surface to one of the side surfaces. A second input output electrode extends from the mounting surface to the other of the side surfaces. Each of the first and second input output electrodes are separated from the outer conductor by a respective conductor-free portion wherein at least one corner of an outer shape of each of the conductor-free portions is formed as a continuous line having no right angles.

Abstract: A coaxial cavity resonator is described. The resonator includes a tapered inner conductor for increasing the Q of the cavity.