Abstract: A filter with a low-noise amplifier includes: two amplification circuits, a first 3-dB hybrid circuit which is connected to an input side of the amplification circuits, a second 3-dB hybrid circuit which is connected to an output side of the amplification circuits, and a filter which is connected to one input terminal of the first 3-dB hybrid circuit. The other input terminal of the first 3-dB hybrid circuit is subjected to matched termination. A signal is inputted to an input terminal of the filter and is outputted from one output terminal of the second 3-dB hybrid circuit and the other output terminal of the second 3-dB hybrid circuit is subjected to matched termination.

Abstract: A piezoelectric filter is one not changing in the holding position of resonator in spite of impulse, small in the number of parts, easy to assemble from one direction, small, thin, and stable in characteristic. For example, as shown in FIG. 7, on electrode patterns on a package 10 forming wiring electrode patterns 11, holding protrusions 13 for holding resonators, and partition boards 14 for positioning resonators, a rectangular plate type piezoelectric resonators 12 are adhered with conductive adhesive. The rectangular plate type piezoelectric resonators 12 and the package 10 are adhered and reinforced from above with a vibration absorbing member 15, and wiring is formed from above the resonators by a wire bonding 16, thereby wiring resonators in a ladder form. Or, as shown in FIG.

Abstract: A frequency synthesizer that can switch an output frequency fast and generates little spurious output is provided. This frequency synthesizer comprises a phase locked loop including a voltage-controlled oscillator, a high frequency divider, a phase frequency comparator and a low-pass filter. The divisor controller circuit supplies a divisor that varies cyclically to the high frequency divider for a fractional dividing operation. When switching the output frequency, a passing bandwidth of the low-pass filter is enlarged to widen a loop bandwidth of the phase locking loop for fast switching. After switching, the passing bandwidth of the low-pass filter is reduced to narrow the loop bandwidth for reduction of a spurious output, at the timing when a predetermined period has passed for the switched output frequency to stabilize substantially.

Abstract: A piezoelectric device includes a piezoelectric plate provided with at least one electrode at almost a central portion of each face; a first plate made of an ionic material having a recessed portion to cover the at least one electrode at one face to face the piezoelectric plate; and a second plate made of an ionic material having a recessed portion to cover the at least one electrode at one face to face the piezoelectric plate. Each of the at least one electrode is packaged by direct bonding the piezoelectric plate with the first plate and the second plate so as to be sandwiched therebetween. A package includes a body member made of an ionic material provided with a recessed portion or an opening, having a flat face around the recessed portion or the opening; and a covering member made of an ionic material having a flat face to cover the body member.

Abstract: This is a PLL frequency synthesizer having a reference divider for dividing a reference source signal, and an RF divider for dividing the output of a voltage controlled oscillator, wherein when changing over the frequency, first the division value of the RF divider changes periodically to become a fractional division value in average, and after the frequency is nearly changed over, the RF divider is set in a conventional integer division operation, therefore, the frequency can be changed over at high speed by the fractional division operation high in reference frequency, and after the changing, a low spurious signal characteristic may be realized.

Abstract: A piezoelectric device includes a piezoelectric plate provided with at least one electrode at almost a central portion of each face; a first plate made of an ionic material having a recessed portion to cover the at least one electrode at one face to face the piezoelectric plate; and a second plate made of an ionic material having a recessed portion to cover the at least one electrode at one face to face the piezoelectric plate. Each of the at least one electrode is packaged by direct bonding the piezoelectric plate with the first plate and the second plate so as to be sandwiched therebetween. A package includes a body member made of an ionic material provided with a recessed portion or an opening, having a flat face around the recessed portion or the opening; and a covering member made of an ionic material having a flat face to cover the body member.

Abstract: An antenna for mobile communication includes a sleeve antenna having a feed point; at least one linear parasitic element insulated electrically form the sleeve antenna; and a supporting means for supporting the sleeve antenna and the linear parasitic element. The supporting means supports the sleeve antenna and the linear parasitic element so that the feed point of the sleeve antenna is located at a different elevation from an elevation of a central point of the linear parasitic element.

Abstract: An antenna for mobile communication of this invention comprises a first metal plate having a slit, a second metal plate opposed to the first metal plate and electrically connected to the first metal plate, two metal foils connected to the second metal plate, and a cable for supplying feed signals to the first metal plate and the second metal plate, the cable including a first conductor connected to the first metal plate via a capacitor and a second conductor connected to the second metal plate.

Abstract: In a piezoelectric resonator having a piezoelectric bar formed in a substantial rectangular parallelopiped and electrodes formed on a pair of confronting surfaces of the piezoelectric bar for resonating in the length expander mode, the piezoelectric bar has at least a bevel portion extending the longitudinal direction. In a ladder filter having series and parallel piezoelectric resonators, the series piezoelectric resonator has the bevel portion to shift a frequency of a spurious response to that of the parallel piezoelectric resonator to suppress the spurious response. It is disclosed that a second piezoelectric resonator has a piezoelectric bar formed in a rectangular parallelopiped has a length L, a width W, and a thickness T wherein L>W>T; and electrodes formed on a pair of confronting surfaces defined by L and T. Another ladder filter includes the second piezoelectric resonator as the series resonator to decrease a capacitance between the electrodes to increase an amount of attenuation.

Abstract: Disclosed is a TEM mode resonator having as a means for adjusting the resonance frequency a simple frequency adjusting mechanism appropriate for size reduction while permitting easy mounting of a varactor diode for varying the resonance frequency thereto. Below a strip transmission line 2 is provided a slot 7 having a length L perpendicular to the transmission line as located at an outer ground conductor surface 3 of a one-fourth wavelength type microstrip line resonator having its one end short-circuited. According as increasing the slot length L, the resonance frequency of the resonator reduces, which characteristic is utilized as a means for adjusting the resonance frequency. By connecting a varactor diode at a center portion of the slot line and varying the voltage applied to the diode, the resonance frequency can be varied.

Abstract: A small-sized antenna device is used for portable telephone equipment and is capable of preventing the receiving strength from being degraded due to a change in the application environment as well as the mounting thereof onto a small radio equipment case. The antenna device has a linear antenna for producing an electric current flux and a coil-shaped antenna for producing a magnetic current flux including a plurality of half-wavelength helical coils connected in series so as to have two adjacent coils coiled in opposite directions with respect to each other, and carries out polarization diversity. Degradation in the characteristics of both antennas due to differences in operational principle can be prevented from taking place simultaneously, resulting in realizing a good reception of a radiowave. In addition, the antenna axes of both antennas can be disposed in parallel and close to each other, thus miniaturizing the device itself.

Abstract: A small antenna comprising a dielectric substrate, a radiation element provided on one major surface of the dielectric substrate, a ground element provided on the other major surface of the dielectric substrate. A feed point on the ground element is located at a position where a voltage of a standing voltage wave induced on the ground element becomes minimum. The antenna may be further provided with a short-circuit element for electrically connecting one ends of the radiation and ground elements.

Abstract: A coaxial line-to-microstrip line transition device including a coaxial line, a microstrip line circuit, and a conductive connection part. The inner conductor of the coaxial line is connected with a microstrip line of the microstrip line circuit. The connection part includes a semi-cylindrical plate which is connected with the outer conductor of the coaxial line by grasping it, and a flat plate which is connected at a surface thereof with a earth layer surface of the microstrip line circuit. The microstrip line is mounted on one surface of a dielectric substrate, and the earth layer is mounted on the other surface of the dielectric substrate. The dielectric substrate is mounted on a chassis which is either provided separately or shared by the flat plate of the connection part which is extended in size. Preferably, a through-hole is provided at least one of the semi-cylindrical plate and the flat plate to be filled with a conductive material.

Abstract: A temperature-stabilized MIC solid state oscillator in the form of a planar transmission circuit has two strip line resonators respectively having chip capacitors inserted serially in the middle of the strip lines. Both of the chip capacitors have linear capacitance temperature characteristics. One strip line resonator operates as a band rejection filter and as a load circuit of an oscillating device. The other strip line resonator operates as a serial resonator to ground a port of the oscillating device that should be grounded. The oscillating frequency characteristics versus temperature are compensated in an excellent manner due to the provision of the two strip line resonators.

Abstract: A solid-state MIC oscillator in the form of a planar transmission circuit has a band rejection filter as a load circuit of an oscillation device. The band rejection filter is a resonator coupled to a transmission line which connects the oscillation device with an oscillator load. The load impedance of the oscillation device is adjusted to the oscillating condition by the position of the resonator. A simple capacitive susceptance stub is connected to the transmission line near the coupling point of the resonator. Variation of the oscillator frequency characteristics versus temperature caused by variation of the oscillator load is improved in an excellent manner due to the provision of the simple capacitive susceptance stub.