A ceramic filter employs a novel tuning process which avoids the necessity of etching or abrading plating on the surface of the filter. The tuning is provided by determining a selected frequency related characteristic of the dielectric making up the block portion of the ceramic filter. For example, the quarter wave length frequency of the block may be measured. Next, plating artwork is designed in accordance with the determined selected frequency related characteristic. The artwork is then used for selectively applying a conductive material to a surface of the block in order to shift the determined selected frequency related characteristic to a desired (specified) frequency characteristic. By appropriately designing the artwork based on the determined selected frequency related characteristic, no etching or abrading to the plating on the block is required.

Tuneless monolithic ceramic filter manufactured by using an art-work mask process

Coupled transmission line resonators, such as those in a solid-dielectric ceramic block filter, are fabricated with tuning regions formed by notches in the outer conductor extending longitudinally parallel with the inner conductors from both the low-impedance ends and the high-impedance ends of the resonators. Removing conductive material from the notches in the vicinity of the low-impedance ends of the resonators decreases their resonant frequencies; removing conductive material from the notches in the vicinity of their high-impedance ends increases their resonant frequencies. Sensitivity of tuning depends on the depth of the notches. By situating all tuning regions along a common side of a filter, tuning both higher and lower in frequency may be accomplished without a need to re-orient the filter in a production-line fixture.

Ceramic block filter with bidirectional tuning

PURPOSE:To attain trimming at a high speed with high accuracy by measuring the initial resonance frequency of a dielectric resonator being a processing object and deciding a removed area of a surface electrode to be trimmed depending on a difference from an object frequency corrected by trimming. CONSTITUTION:Dielectric resonators 1 are carried in a line while the direction is being selected and they are fed to a 1st turntable 2 and a 2nd turntable 3 sequentially. Four-stop index tables are adopted for the tables 2, 3 and they are driven in the reverse direction as shown by the arrow. Then the oscillator (not shown) to generate a laser beam 4 used for trimming is arranged on a line tying the rotation center of the tables 2, 3 and each resonator 1 is trimmed by using positions 5, 6 provided to the tables 2, 3 as an index. The resonance frequency of the resonator 1 is measured at any time by using antenna measurement terminals 7, 8 and 9, 10 provided around the tables 2, 3 and the resonator 1 is trimmed and turned by 90 deg. and taken out after the measuremet is finished.

Laser trimming device for adjusting resonance requency of dielectric resonator

PURPOSE:To attain the control of high accuracy without accompanying the mechanical grinding of a dielectric by removing the opened surface side part of an outer circumference conductor in a resonator from the outer circumference of the dielectric and controlling a resonance frequency. CONSTITUTION:The resonance frequency of an uncontrolled resonator 7 is measured and the removal quantity of an opened surface 6 side part in an outer circumference conductor 3 is determined. The resonator 7 is held by jigs 8 and revolved around a shaft line. Then, the moving quantity of an X-Y table 9, which corresponds to the removal quantity of the outer circumference conductor 3, and the irradiation time of a laser light 11 are programmed to a laser device 10 in advance and the X-Y table 9 and laser light 11 are controlled by the selection of an operator. Then, the opened surface 6 side part of the outer circumference conductor 3 is removed. After that, the resonance frequency is measured and confirmed to be controlled to the desired resonance frequency.

Resonance frequency control method for coaxial type dielectric resonator

A dielectric filter in which an open-circuiting end surface of a dielectric ceramic block is provided with a conductor pattern for each of the inner resonators and an additional conductor for each of the outermost resonators, the conductor patterns are intended to capacitively coupling the resonators with each other, and the additional conductors are intended to increase the effective resonant length of the outermost resonators, thereby the resonant frequencies of the resonators can be made substantially agree with each other.

Dielectric filter with elevated inner regions adjacent resonator openings

PURPOSE:To adjust easily and accurately a resonance frequency by providing an electrode for capacitance adjustment formed with many metallic pieces in mesh form to an open end side of a dielectric resonator so as to control the area of the electrode. CONSTITUTION:The electrode 35 for capacitance adjustment made of many metallic pieces divided minutely is provided to an upper face (open end side) 34 of the dielectric resonator 31 consisting of one dielectric and the electrode 35 is connected to a metallic rod (inner conductor) 36. In cutting the resonator into halves and viewing them from the X direction, a dielectric 53 is found between the electrode 52 and a side face 54, and when the electrode 52 and the side face 54 are approached together, the capacitance 55 formed by them is increased and the resonance frequency of the resonator is decreased. Thus, when B (1, 1) and B (1, n) are cut off from the metallic pieces divided minutely of the electrode, it is found that the resonance frequency is increased most. The resonance frequency is adjusted easily and accurately by controlling the area of the electrode in this way.

Takuro Sato

Papers

Dielectric resonator and method for adjusting resonance frequency of dielectric resonator