Abstract: An outer conductor, an input terminal electrode, an output terminal electrode, a voltage controllable terminal electrode, and two separated electrodes are formed on the outer face of a dielectric block. Furthermore, on the upper face of the dielectric block, PIN diodes which are voltage controllable reactance elements, and inductors for voltage-controlling the PIN diodes, and a coupling adjustment capacitor are mounted. Frequency shifting capacitors are formed by generation of electrostatic capacitances between the separated electrodes and the inner conductors of the resonance holes, respectively.

Abstract: A plurality of cylindrical inner conductor portions having different diameters are connected with each other to form an inner conductor. The inner conductor portions include high-impedance portions and low-impedance portions. The inner conductor is formed within an outer conductor with a nonuniform inner diameter. The inner conductor is formed so that the axial length of some of the inner conductor portions forming the high-impedance portions is smaller than the axial length of the other inner conductor portions forming the high-impedance portions, and the diameter of the inner conductor portions forming the high-impedance portions is greater than a predetermined minimum diameter.

Abstract: An inner conductor comprising high impedance portions and low impedance portions alternately connected to each other is disposed in the center of an outer conductor having a substantially square cross-section. Two holes are formed in one side of the outer conductor so as to extend through the wall of the outer conductor. A substantially &pgr;-shaped coupling line comprising a main line portion and probe-connecting portions is formed on the surface of a dielectric substrate. Probes made of conductor rods are connected at the ends, respectively. A resistor is provided at one end of the main line of the coupling line. The other end of the main line functions as an output terminal, and can be connected to an external circuit. The probes are inserted through the holes. The dielectric substrate is disposed inside of the outer conductor at predetermined positions.

Abstract: An inner conductor comprising high impedance portions and low impedance portions alternately connected to each other is disposed in the center of an outer conductor having a substantially square cross-section. Two holes are formed in one side of the outer conductor so as to extend through the wall of the outer conductor. A substantially &pgr;-shaped coupling line comprising a main line portion and probe-connecting portions is formed on the surface of a dielectric substrate. Probes made of conductor rods are connected at the ends, respectively. A resistor is provided at one end of the main line of the coupling line. The other end of the main line functions as an output terminal, and can be connected to an external circuit. The probes are inserted through the holes. The dielectric substrate is disposed inside of the outer conductor at predetermined positions.

Abstract: A filter with which it is possible to control the relationship between a pass band and an attenuation band. In this filter, for example, a single-stage trap filter is electrically connected to a three-stage band pass filter via a coupling capacitor. The trap filter has a serial resonance section composed of a resonator and a resonance capacitor. The serial resonance section is connected in parallel to a capacitive reactance element (capacitor), and a serial circuit composed of an inductive reactance element (inductor) and a PIN diode as a switching element. The capacitive reactance element and the inductive reactance element both serve to make an admittance of the trap circuit substantially zero.

Abstract: A plurality of cylindrical inner conductor portions having different diameters are connected with each other to form an inner conductor. The inner conductor portions include high-impedance portions and low-impedance portions. The inner conductor is formed within an outer conductor with a nonuniform inner diameter.

Abstract: A frequency variable filter in which both the frequency of an attenuation pole and the attenuation bandwidth can be varied. In the frequency variable filter, two serial resonance sections composed of resonators and resonance capacitors are electrically connected to each other via a capacitor. The respective resonator in each of the serial resonance sections is electrically connected in parallel with a corresponding serial circuit composed of a frequency shifting capacitor and a PIN diode. A coupling capacitor electrically connects the junctions defined respectively between the frequency shifting capacitor and the PIN diode in each of the serial circuits.

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 and a dielectric duplexer adapted to two frequency bands formed by using a single component are disclose, in addition to a communication apparatus using the same. In this case, since a dielectric block used as the single component can be easily molded and grasped, production efficiency can be enhanced. The dielectric duplexer adaptable to two frequency bands is formed by disposing inner-conductor-formed holes acting as &lgr;/2 resonators and &lgr;/4 resonators in the single dielectric block.

Abstract: A filter with which it is possible to control the relationship between a pass band and an attenuation band. In this filter, for example, a single-stage trap filter is electrically connected to a three-stage band pass filter via a coupling capacitor. The trap filter has a serial resonance section composed of a resonator and a resonance capacitor. The serial resonance section is connected in parallel to a capacitive reactance element (capacitor), and a serial circuit composed of an inductive reactance element (inductor) and a PIN diode as a switching element. The capacitive reactance element and the inductive reactance element both serve to make an admittance of the trap circuit substantially zero.

Abstract: There is disclosed a duplexer comprising: a first external terminal; a second external terminal; an antenna terminal; a first frequency variable filter electrically connected between the first external terminal and the antenna terminal, and composed of at least one resonator and a reactance element electrically connected to the resonator and capable of being voltage-controlled; a second frequency variable filter electrically connected between the second external terminal and the antenna terminal, and composed of at least one resonator and a reactance element electrically connected to the resonator and capable of being voltage-controlled; the predetermined reactance element of the first frequency variable filter being in the on state when the reactance element of the second frequency variable filter is in the on state.

Abstract: The invention provides a filtering device of the transmission-reception switched type which can be constructed in a form with a reduced size at a low cost without having to use circuit elements such as a capacitor, a coil, and a transmission line forming a phase shift circuit which are not essential to the filtering device. Inner conductors serving as distributed-parameter resonance lines are formed in a dielectric block. There is provided a coupling line coupled with particular inner conductors. The open-circuited ends of these particular inner conductors are connected to an outer conductor via corresponding diode switches so that transmission and reception filters are switched from each other when either diode switch is selectively turned on.

Abstract: The invention provides a filtering device of the transmission-reception switched type which can be constructed in a form with a reduced size at a low cost without having to use circuit elements such as a capacitor, a coil, and a transmission line forming a phase shift circuit which are not essential to the filtering device. Inner conductors serving as distributed-parameter resonance lines are formed in a dielectric block. There is provided a coupling line coupled with particular inner conductors. The open-circuited ends of these particular inner conductors are connected to an outer conductor via corresponding diode switches so that transmission and reception filters are switched from each other when either diode switch is selectively turned on.

Abstract: A frequency variable filter in which both the frequency of an attenuation pole and the attenuation bandwidth can be varied. In the frequency variable filter, two serial resonance sections composed of resonators and resonance capacitors are electrically connected to each other via a capacitor. The respective resonator in each of the serial resonance sections is electrically connected in parallel with a corresponding serial circuit composed of a frequency shifting capacitor and a PIN diode. A coupling capacitor electrically connects the junctions defined respectively between the frequency shifting capacitor and the PIN diode in each of the serial circuits.

Abstract: A conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block, for example at an end surface. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode may be connected to the conducting film formed on the outer surface of the dielectric block, for example at a side surface. The coupling electrode is non-linear, preferably L-shaped.

Abstract: An outer conductor, an input terminal electrode, an output terminal electrode, a voltage controllable terminal electrode, and two separated electrodes are formed on the outer face of a dielectric block. Furthermore, on the upper face of the dielectric block, PIN diodes which are voltage controllable reactance elements, and inductors for voltage-controlling the PIN diodes, and a coupling adjustment capacitor are mounted. Frequency shifting capacitors are formed by generation of electrostatic capacitances between the separated electrodes and the inner conductors of the resonance holes, respectively.

Abstract: A conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on a side surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the coupling electrode extends toward the conducting film formed on the opposite side surface and one end surface of the dielectric block. The above structure allows an increase in the degree of freedom in the design of the characteristics including the resonance frequency and unloaded Q of the dielectric waveguide resonator.

Abstract: A dielectric duplexer or multiplexer in which a conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode is either connected to the conducting film formed on the outer surface of the dielectric block or terminated inside the dielectric block.

Abstract: An antenna-duplexer and communication apparatus in which relative phase distortion of transmitted waves and intrusive waves is low, and which are small-scale. An antenna-duplexer comprises a transmission side circuit, electrically connected between a transmission terminal and an antenna terminal, and a reception side circuit, electrically connected between a reception terminal and the antenna terminal. Two PIN diodes, which are connected in series, are connected only to a resonator of the transmission side circuit which is electrically connected closest to the antenna terminal, and a voltage control terminal is connected to the anodes of the PIN diodes, thereby dividing the high-frequency voltage. One PIN diode is connected to each of the other resonators.

Abstract: A dielectric duplexer or multiplexer in which a conducting film is formed on a dielectric block in a dielectric waveguide resonator, and a through-hole is formed in the dielectric block. The unloaded Q is set by selecting the outside dimensions of the dielectric block. The resonance frequency is set by selecting the size and location of the through-hole as well as the outside dimensions of the dielectric block. A terminal electrode is formed on the outer surface of the dielectric block. A coupling hole is formed in the dielectric block and a coupling electrode is formed on the inner surface of the coupling hole. One end of the coupling electrode is connected to the terminal electrode and the other end of the coupling electrode is either connected to the conducting film formed on the outer surface of the dielectric block or terminated inside the dielectric block.