JPH066107A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a small sized dielectric filter whose pass band characteristic is adjusted by increasing the capacitive coupling between resonators. CONSTITUTION:A dielectric board 11 having recessed grooves for a dielectric filter and a dielectric flat plate 12 are adhered and a prescribed conductor film is formed and the filter comprising combinations of 1/4 wavelength TEM resonators is formed. The conductor patterns 16 are formed on the adhered face between the resonators and the conductor patterns and an inner conductor are connected to obtain capacitor coupling between the conductor patterns 16 opposite to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a dielectric filter, and more particularly to an electrode structure for obtaining a capacitive coupling between the resonators.

[0002]

2. Description of the Related Art Various dielectric filters are used in a high frequency range from the UHF band to the microwave band. Among them, a dielectric filter is often used which is a combination of a TEM resonator having a through hole, an inner conductor formed in the through hole, and an outer conductor formed on the outer peripheral surface. There are ones that are configured by connecting individual resonators and ones that are integrated in a block.

In those dielectric filters, capacitive coupling between the resonators, in order to adjust the passband characteristics,
It regulates inductive binding. In order to strengthen the capacitive coupling, a capacitor is connected between the resonators, or a conductor pattern drawn from the inner conductor of the resonator to the open end face is formed to face each other to obtain the capacitance.

In the field of dielectric filters, there is a demand for miniaturization and thinning, and the wavelength must be shortened as the frequency band rises, so that the dimensions must be shortened.

[0005]

As described above, as the size and the thickness of the resonator are reduced, the structure for obtaining the capacitive coupling between the resonators is also restricted, and a simple structure is necessary and sufficient. There is a need for an electrode structure that is able to obtain a good capacitive coupling.

It is also desirable to avoid adding or connecting any special components to obtain capacitive coupling between the resonators.

The present invention solves such problems and provides a dielectric filter which can obtain a sufficient capacitive coupling with a simple structure and manufacturing process.

[0008]

According to the present invention, a conductor film connected to an inner conductor is arranged inside a dielectric block, and the conductor film forms a capacitance between the inner conductors of a resonator. This is to solve the above problems.

That is, a flat second dielectric substrate is adhered on the grooved surface of a first dielectric substrate having a plurality of linearly extending parallel concave grooves, and the second dielectric substrate is bonded to the inside of the concave groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. In a dielectric filter in which a plurality of resonators are formed by forming a short-circuit conductor on one of the end faces of the opening of the concave groove, the inner conductor of one resonator is attached to the surface of at least one of the dielectric substrates to be bonded. It is characterized in that it is provided with a conductor film which is connected to the inner conductor of the adjacent resonator and closely faces the inner conductor of the adjacent resonator to form a capacitance.

Capacitive coupling can also be strengthened by forming conductive films from adjacent resonators respectively and forming them so as to face each other on the surfaces to be bonded of the dielectric substrate. Further, this conductor film may be further drawn to the open end face of the dielectric block and connected to the conductor film formed near the inner conductor at the open end face.

[0011]

Since the conductor film connected to the inner conductor is formed, a large capacitance can be obtained, and at the same time, the capacitance can be adjusted by the size, shape or position.

When the dielectric block is pulled out to the open end face, the capacitance can be easily adjusted by removing or adding the conductor film on the open end face.

[0013]

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

FIG. 1 is a perspective view showing a state before assembly of a dielectric filter according to the present invention. Two parallel grooves
A flat second dielectric substrate (12) is adhered to the side of the first dielectric substrate (11) having the concave groove (14) with glass or the like. This forms a block of dielectric with two parallel through holes. In the present invention, the conductor pattern 16 is previously formed on the adhesive surface of the dielectric substrate. It is preferable that the conductor patterns 16 are formed so as to extend from the edge portions of the recessed grooves 14 in the direction of the adjacent recessed grooves, respectively, and are parallel conductor patterns on the dielectric substrate between the two recessed grooves 14.

FIG. 2 shows that after the bonding and the formation of the conductor film,
FIG. 3 is a perspective view showing a dielectric filter according to the present invention. Figure 1
2 has a structure in which two through holes 25 are formed in a dielectric block formed by adhering a dielectric substrate 21 corresponding to the dielectric substrate 11 and a dielectric substrate 22 corresponding to the dielectric substrate 12 of FIG. . An inner conductor is formed on the surface of the through hole 25, and an outer conductor 27 is formed on the outer peripheral surface parallel to the extending direction of the through hole 25. Although not shown in the drawing, a short-circuit conductor is formed on one end face of the opening of the through hole 25, and a quarter wavelength TEM is formed.
A resonant dielectric filter is constructed.

The conductor pattern 26 formed on the joint surface is connected to the inner conductor formed on the surface of the through hole 25. As a result, a capacitance is formed between the resonators by the conductor film 26 connected between the inner conductors of the conductor film formed in the through hole 25. The terminal electrode 28 is formed not only on the end surface parallel to the extending direction of the through hole 25 but also on the surface adjacent to the end surface. This is to enable surface mounting on the printed wiring board. Of course, the terminal electrode 28 must be insulated from the outer conductor.

In the example of FIG. 1, the conductor pattern 16 is formed on the side of the dielectric substrate 11 having the concave groove, but when actually manufactured, as shown in FIG. 3, a flat dielectric substrate 32 is formed. It is easier to form on the surface of. At this time, it is advisable to form the conductor film 36 which serves as an electrode for input / output coupling together with the conductor film 36 for obtaining the coupling between the resonators.

In the above example, the conductor patterns are respectively drawn from the two resonators, but they may be drawn from only one and formed so as to face a position close to the inner conductor of the other resonator. .

Further, as shown in FIG. 4, a conductor pattern for obtaining coupling between the resonators may be connected to the conductor pattern 46 formed on the open end face. This structure can be realized by drawing out the conductor pattern formed before bonding to the edge and the end surface of the groove. Normally, the open end face is polished to adjust the resonance frequency, so that the conductor pattern 46 on the open end face is formed after polishing. Also, in this structure, since the conductor pattern is also formed on the open end surface,
The capacitance between the inner conductors can be increased. Also,
The capacitance can be adjusted depending on the size and position of the conductor pattern, or can be adjusted by grinding or adding.

FIG. 5 is an explanatory diagram of characteristics of the dielectric filter according to the present invention. A 1.6 mm thick substrate with a groove and a 0.9 mm flat plate substrate are glued together, and the grooves have a center spacing of 2.5 mm, a width of 1 mm, and a depth of 0.9 mm. This is an example of a dielectric filter with dimensions of 2.7 mm x 6.5 mm. The length of the groove depends on the resonance frequency, but is about 9.5 m
When m is set, a filter having a center frequency of 1575.4 MHz and an insertion loss of about 2 dB is obtained, and its pass band characteristic is as shown in FIG. As shown in the figure, the attenuation characteristic on the low frequency side of the pass band is steep.

[0021]

According to the present invention, it becomes easy to obtain a dielectric filter having a strong capacitive coupling between resonators, whereby the frequency band pass characteristic can be adjusted.
Moreover, no special parts are required and only the formation of the conductor pattern is required, so that an inexpensive dielectric filter can be obtained.

Moreover, when the conductor pattern is drawn out to the open end face, it is easy to adjust the capacitance, and the capacitance increases.
Either reduction is possible.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment (before assembly) of the present invention.

FIG. 2 is a perspective view showing an embodiment (after assembly) of the present invention.

FIG. 3 is a perspective view showing another embodiment of the present invention.

FIG. 4 is a perspective view showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram of characteristics of the dielectric filter according to the present invention.

[Explanation of symbols]

 11, 21: (first) dielectric substrate 12, 22, 32: (second) dielectric substrate 16, 26, 36: conductor pattern 46: conductor pattern

Claims (3)

[Claims] 1. A flat second dielectric substrate is adhered onto the grooved surface of a first dielectric substrate having a plurality of parallel grooves extending linearly, and a flat second dielectric substrate is adhered to the inside of the groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. In a dielectric filter in which a plurality of resonators are formed by forming a short-circuit conductor on one of the end faces of the opening of the concave groove, the inner conductor of one resonator is attached to the surface of at least one of the dielectric substrates to be bonded. A dielectric filter comprising: a conductor film connected to the inner conductor of an adjacent resonator to form a capacitance in close proximity to the inner conductor of the resonator. 2. A flat second dielectric substrate is adhered onto the grooved surface of a first dielectric substrate having a plurality of parallel grooves extending linearly, and a flat second dielectric substrate is adhered to the inside of the groove and the second dielectric substrate. The inner conductor is formed on the surface of the dielectric substrate facing the groove, and the outer conductor is formed on the unbonded surface of the first and second dielectric substrates and the end surface parallel to the extending direction of the groove. In a dielectric filter in which a plurality of resonators are formed by forming a short-circuit conductor on one of the end surfaces of the recessed groove, a surface of at least one dielectric substrate to which two adjacent resonators are bonded A dielectric filter comprising: two conductor films each connected to an inner conductor and closely facing each other on a surface of a dielectric substrate between the resonators to form a capacitance. 3. The dielectric filter according to claim 2, wherein the two conductor films formed on the surfaces to be adhered are connected to the two conductor films formed on the open end faces, respectively.