JP3306137B2 - Method of adjusting resonance frequency of dielectric filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting the resonance frequency of a dielectric filter, and more particularly to a method for adjusting the resonance frequency by adjusting the distance between a terminal electrode and an outer conductor.

[0002]

2. Description of the Related Art Various dielectric filters are used in a high frequency range such as a UHF band to a microwave band. Among them, a dielectric filter including a TEM resonator in which an inner conductor is formed in a portion having a through hole and an outer conductor is formed on an outer peripheral surface thereof is often used. There are a type in which separate resonators are connected and a type in which a plurality of resonators are integrated into a block.

In these dielectric filters, input and output coupling capacitances must be formed between the input and output stages and the inner conductor of the resonator. The coupling capacity can be changed by connecting a capacitor or inserting a metal rod coated with a dielectric into a through-hole formed with an inner conductor, or by using a dielectric substrate near the inner conductor. Various methods for inserting a metal rod into a hole provided in a body or forming a metal film on an outer peripheral surface separately from an outer conductor have been considered.

In the field of dielectric filters, there is also a demand for miniaturization and thinning, and the size must be shortened because the wavelength becomes shorter as the frequency band rises. Therefore,
The present inventor has previously proposed in Japanese Patent Application No. 4-179112 a structure in which a dielectric filter is formed by bonding two dielectric substrates and an input / output electrode is formed on the bonded surface.

[0005]

If it is necessary to increase the required bandwidth of the dielectric filter, the value of the input / output coupling capacitance must be increased. However, when the size of the filter is reduced, the size of the electrode forming the coupling capacitance is also restricted, and it is difficult to obtain a large capacitance. Also, Q
There is also a problem of a decrease in the temperature.

Further, it is desirable to avoid adding or connecting special components in order to obtain a large input / output coupling capacitance. Further, a structure that can finely adjust the resonance frequency is desirable.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and adjusts the resonance frequency suitable for a dielectric filter for connecting a dielectric resonator at an input / output end to an external circuit with a simple structure and a simple manufacturing process. It provides a method.

[0008]

According to the present invention, a terminal electrode is connected to a conductor film connected at an impedance matching point to an inner conductor of a resonator at an input / output end of a dielectric block, and the terminal electrode is connected to an outer conductor. The above-mentioned problem is solved by adjusting the distance.

That is, a flat plate-shaped second dielectric substrate is adhered on the grooved surface of the first dielectric substrate having a plurality of linear grooves extending linearly, and the inside of the groove and the second dielectric substrate are adhered to each other. An inner conductor is formed on a surface of the dielectric substrate facing the concave groove, and an outer conductor is formed on an unbonded surface of the first dielectric substrate and the second dielectric substrate and an end surface parallel to the extending direction of the concave groove. In the method of adjusting the resonance frequency of a dielectric filter in which a plurality of resonators are formed by forming a short-circuit conductor on one of the exposed end faces of the groove, input / output is performed from an end face parallel to the extending direction of the groove.
Extends in the direction of the groove that becomes the vibration
Conductive film connected to a conductor has at least one dielectric substrate
The conductor film is formed on the adhesive surface of
Terminal formed on the end face parallel to the direction insulated from the outer conductor
The characteristic feature is that the resonance frequency is adjusted by changing the distance between the terminal conductor film and the outer conductor and connected to the terminal conductor film.

[0010]

The resonance frequency is reduced by increasing the distance from the terminal electrode. Fine adjustment of the resonance frequency is possible even after assembly and mounting.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a state before assembling a dielectric filter to which the present invention is applied. A flat plate-shaped second dielectric substrate 12 is bonded to the side of the first dielectric substrate 11 having the two parallel concave grooves 14 with the concave grooves 14 using glass or the like.
As a result, a dielectric block having two parallel through holes is formed. In the present invention, the dielectric substrate 12
The conductor pattern 16 is previously formed on the bonding surface of.
The conductor pattern 16 is formed so as to extend from an end face parallel to the extending direction of the groove 14 to a portion facing the groove, and after bonding, the groove 14 of the dielectric substrate 11 and the dielectric substrate facing the groove.
It is formed so as to be connected to the inner conductor formed on the surface of 12.

FIG. 2 shows a state after bonding and after forming a conductive film.
FIG. 2 is a perspective view showing the same dielectric filter as FIG. 1. It has a structure in which two through holes 25 are formed in a dielectric block in which a dielectric substrate 21 and a dielectric substrate 22 are bonded. An inner conductor is formed on the surface inside the through hole 25,
The outer conductor 27 is formed on the outer peripheral surface parallel to the direction in which the outer conductor 27 extends. FIG. 2 shows an example of two elements of the interdigital type. The left resonator has an open end face on the front side, the right resonator has a short-circuit end face on the front side, and a dielectric of quarter-wave TEM resonance. A body filter is configured.

The conductor pattern (16) formed on the joint surface shown in FIG. 1 is connected to the terminal electrode 28 at the end face of the dielectric substrate, and the inner conductor formed by the conductor film formed in the through hole 25 and the terminal electrode 28 are connected to each other. Connect directly. The connection between the conductor pattern (16) and the inner conductor is made at an impedance matching point such as the 50 ohm point of the inner conductor of the resonator at the input / output end. As a result, the input / output terminal is directly connected to the inner conductor of the resonator at the input / output end in a state where the impedance is matched.

The terminal electrode 28 is a conductor film formed straddling two dielectric substrates, and is insulated from the outer conductor 27 but formed close to it. Therefore, a capacitance is formed between the input / output terminal and the ground. Terminal electrode
28, when any opposing portion of the outer conductor 27 is trimmed, the magnetic field distribution changes and the resonance frequency changes. Increasing the interval changes the direction in which the resonance frequency decreases. By this trimming, a frequency change (Δf /
f ₀ ) can be changed by about 1%.

In the above example, an interdigital type two-element dielectric filter has been described. However, a block having three or more elements can be used, and a comb-line type dielectric filter having an open end face and a short-circuit end face can be used. The same applies to body filters.

[0017]

According to the present invention, not only a small-sized dielectric filter can be obtained by eliminating the need for an input / output coupling capacitance, but also
Adjustment of the resonance frequency is also facilitated.

As a result, a dielectric filter requiring a wide pass band can be obtained at a small size and at low cost.

[Brief description of the drawings]

FIG. 1 shows a dielectric filter to which the present invention is applied (before assembly).
Perspective view showing

FIG. 2 shows a dielectric filter to which the present invention is applied (after assembly).
Perspective view showing

[Explanation of symbols]

 11, 21: (first) dielectric substrate 12, 22: (second) dielectric substrate 16: conductor pattern 27: outer conductor 28: terminal electrode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 1/20-1/219 H01P ^7/ 00-7/10

Claims (2)

(57) [Claims] A first dielectric substrate having a plurality of linear grooves extending in parallel and a flat plate-shaped second dielectric substrate adhered to the grooved surface of the first dielectric substrate; An inner conductor is formed on a surface of the dielectric substrate facing the concave groove, and an outer conductor is formed on an unbonded surface of the first dielectric substrate and the second dielectric substrate and an end surface parallel to the extending direction of the concave groove. In the method of adjusting the resonance frequency of the dielectric filter in which a plurality of resonators are formed by forming a short-circuit conductor on one of the exposed end faces of the concave groove, the input / output resonator and the input / output resonator are formed from the end face parallel to the extending direction of the concave groove.
To the inner conductor at the impedance matching point
Adhesion of at least one dielectric substrate to the conductive film to be connected
These conductor films are formed in a plane in the direction in which the groove extends.
Terminal conductor formed on the end face of the line, insulated from the outer conductor
A resonance frequency adjustment method for a dielectric filter, wherein the resonance frequency is adjusted by changing the distance between the terminal conductor film and the outer conductor connected to the film . 2. A flat plate-like second dielectric substrate is adhered on a grooved surface of a first dielectric substrate having a plurality of linear grooves extending in a straight line. An inner conductor is formed on a surface of the dielectric substrate facing the concave groove, and an outer conductor is formed on an unbonded surface of the first dielectric substrate and the second dielectric substrate and an end surface parallel to the extending direction of the concave groove. In the method of adjusting the resonance frequency of the dielectric filter in which a plurality of resonators are formed by forming a short-circuit conductor on one of the exposed end faces of the concave groove, the input / output resonator and the input / output resonator are formed from the end face parallel to the extending direction of the concave groove.
To the inner conductor at the impedance matching point
Adhesion of at least one dielectric substrate to the conductive film to be connected
These conductor films are formed in a plane in the direction in which the groove extends.
Terminal conductor formed on the end face of the line, insulated from the outer conductor
A resonance frequency adjusting method for a dielectric filter, characterized in that the resonance frequency is reduced by increasing the distance between the terminal conductor film and the outer conductor connected to the film .