JPH09252205A - Dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a damping pole at the upper side of a pass band without increasing the special manhours for production by controlling the coupling state between both resonators via the conductor film formed on an adhesion surface of the short-circuit end face side. SOLUTION: A flat 2nd dielectric substrate is adhered to a 1st dielectric substrate 11 at the side where two parallel recessing grooves 10 are formed via glass, etc. The conductor patterns 13, 16 and 17 are previously formed on the adhesion surface of the substrate 12. The pattern 13 is formed by a metallic film serving as an inner conductor at the positions opposite to the grooves 10, and the pattern 16 functions to secure connection between an input/ output terminal and the inner conductor. A wide part of the pattern 17 is formed at the end parts of the substrate 12 opposite to the grooves 10. The characteristics of a pass band, etc., are controlled by the shape and size of the wide pattern 17, and a damping pole is formed at the higher side of the pass band.

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 its attenuation characteristic.

[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 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 collecting surface. There are a structure in which individual resonators are connected and a structure in which a plurality of resonators are integrated in a dielectric block.

As a kind of such a dielectric filter,
The inventor has proposed a dielectric filter having a structure in which two dielectric substrates are bonded together in Japanese Patent Application No. 4-17911 (JP-A-5-347504). A groove is formed on one of the dielectric substrates, and the metal film applied to the groove is used as an inner conductor, which is advantageous in that it can be downsized and can be easily manufactured. is there.

FIG. 3 is a perspective view showing an example of the dielectric filter. A first dielectric substrate (31) in which a groove is formed and a flat dielectric substrate (32) are bonded together with glass or the like on the surface having the groove. An inner conductor 33 is formed in the groove portion, an outer conductor 34 is formed on the surface and the end surface other than the bonding surface, and a short-circuit conductor is also formed on one of the end surfaces, not shown, where the groove is opened.
In the figure, the front end face is an open end face on which the conductor film is not formed. The inner conductor 33 is connected to the terminal electrode 35 directly or via a capacitor.

In the above dielectric filter, capacitive coupling and inductive coupling exist between the resonators, but the band pass characteristic is adjusted by adjusting the degree of these couplings.
It has the desired properties. Further, although it is sometimes required to provide an attenuation pole, there has been no effective structure or method to satisfy the demand so far. Attempts have been made to process the dielectric, but all of them have problems such as an increase in the number of manufacturing steps.

[0006]

SUMMARY OF THE INVENTION The present invention provides a small-sized and easy-to-manufacture dielectric filter having an attenuation pole on the upper side of the pass band without requiring a special increase in manufacturing steps. Is.

[0007]

The present invention solves the above problems by improving the shape of the conductor film formed on the adhesive surface of the dielectric filter.

That is, a flat second dielectric substrate is adhered onto the concave surface of a first dielectric substrate having a plurality of parallel concave grooves, and the flat second dielectric substrate is adhered to the inside of the concave groove and the second dielectric substrate. The inner conductor is formed on the surface facing the concave groove of, and the outer conductor is formed on the surfaces of the first dielectric substrate and the second dielectric substrate which are not adhered and the end surface parallel to the extending direction of the concave groove. In a dielectric filter having a plurality of resonators formed with a short-circuit conductor formed on one end surface of the opening of, the short-circuit end surface side of the bonding surface of at least one of the first dielectric substrate and the second dielectric substrate It is characterized by having a conductor film connected to the inner conductor.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A through hole is formed by a groove by adhering two dielectric substrates, and an inner conductor is formed inside the through hole. The outer conductor and the short-circuit conductor are also formed in the same manner. A conductor film, which is electrically connected to the inner conductor, is formed on the short-circuit end face side so as to extend into the bonding surface. It is preferable that the conductor film is integrally formed with the conductor film serving as the inner conductor on the surface of the flat dielectric substrate before bonding.

[0010]

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. A flat second dielectric substrate (12) is adhered to the side of the first dielectric substrate (11) having two parallel concave grooves (10) with the concave groove with glass or the like. This results in a dielectric block with two parallel through holes. In the present invention, the conductor patterns 13, 16 and 17 are formed in advance on the bonding surface of the second flat plate dielectric substrate.

The conductor pattern 13 is a metal film serving as an inner conductor,
It is formed at a position facing the concave groove of the first dielectric substrate 11. The conductor pattern 16 is a conductor pattern that connects the input / output terminal and the inner conductor. In this case, an example is shown in which the input / output terminals are directly coupled to each other at the impedance matching point.

In the dielectric filter according to the present invention, the wide portion 17 of the conductor pattern is formed in the end portion of the second dielectric substrate 12 facing the concave groove of the first dielectric substrate 11. Since the wide portion of the conductor pattern 17 needs to be electrically connected to the inner conductor, it may be formed on the bonding surface of the second dielectric substrate 12 at the same time as the conductor pattern 13 serving as the inner conductor. The wide portion of the conductor pattern 17 is formed so as to be in contact with or close to the short-circuit end face after the dielectric filter is assembled.

Bonding the two dielectric substrates shown in FIG.
The inner conductor is formed in the through hole formed by the concave groove, the outer conductor is formed around the inner hole, and the short-circuit conductor is formed on one end face where the through hole opens, so that the dielectric filter according to the present invention is obtained. As described above, the second dielectric substrate is assembled so that the wide portion of the conductor pattern 17 is located on the short-circuit end face side. When the terminal electrodes are formed, the external appearance becomes similar to that of the dielectric filter shown in FIG.

When the characteristics of the dielectric filter having the above-mentioned structure were measured, the bandpass characteristics shown by the curve 28 in FIG. 2 were shown. A big difference from the conventional one was that the attenuation pole appeared on the high frequency side of the pass band. The center frequency of this filter was 2.1 GHz, and the frequency of the attenuation pole on the high frequency side was 2.6 GHz, with an attenuation of 70 dB.

The characteristics such as the pass band width can be adjusted by the shape and size of the wide conductor pattern added to the short-circuited end face side. It is also possible to add a conductor pattern to the adhesive surface on the open end side to adjust the capacitive coupling.

[0017]

According to the present invention, since the coupling state between the resonators can be controlled by the conductor film formed on the adhesive surface on the short-circuited end face side, the attenuation pole is formed on the high frequency side of the pass band. It becomes possible.

Further, the coupling state can be adjusted only by adding the conductor pattern, the steps such as the processing of the dielectric are not required, and the dielectric filter which is easy to manufacture and low in cost can be obtained.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

FIG. 3 is a perspective view of a conventional dielectric filter.

[Explanation of symbols]

 11: first dielectric substrate 12: second dielectric substrate 13: (for inner conductor) conductor pattern 16: (for input / output) conductor pattern 17: (wide) conductor pattern

Claims (3)

[Claims] 1. A flat second dielectric substrate is adhered on a grooved surface of a first dielectric substrate having a plurality of parallel concave grooves, and the second dielectric substrate is in the concave groove and in the second dielectric substrate. The inner conductor is formed on the surface facing the groove, and the outer conductor is formed on the surfaces of the first dielectric substrate and the second dielectric substrate which are not adhered and on the end faces parallel to the extending direction of the groove. In a dielectric filter having a plurality of resonators formed with a short-circuit conductor formed on one end surface of the opening of, the short-circuit end surface side of the bonding surface of at least one of the first dielectric substrate and the second dielectric substrate , A dielectric filter comprising a conductor film connected to an inner conductor. 2. The dielectric filter according to claim 1, wherein a conductor film serving as an inner conductor and a wide conductor film connected thereto are provided on the surface of the second dielectric substrate on the short-circuited end face side of the substrate. 3. A conductor film serving as an inner conductor and a wide conductor film connected thereto are formed on the surface of the second dielectric substrate on the short-circuit end face side of the substrate, and a conductor film for input / output is formed. The dielectric filter according to claim 1.