JPH066108A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a small sized dielectric filter whose pass band characteristic is adjusted by decreasing the capacitive coupling between resonators. CONSTITUTION:The dielectric filter is so structured that a dielectric base 11 having recessed grooves and a dielectric flat base 12 are adhered and the filter comprises combination of 1/4 wavelength TEM resonators with a prescribed conductor film formed to them. The conductor pattern extended from an open end face between the resonators on an adhered face to the inside is formed and the conductor pattern and an outer conductor 17 are connected by the conductor film 13 on the open end face to decrease the capacitive coupling and to obtain the dielectric filter acted mainly on the inductive coupling.

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 reducing 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 weaken the capacitive coupling, a coupling adjusting hole is formed between the resonators, and a conductor is inserted into the hole.

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 thickness of the resonator are reduced, the structure for reducing the capacitive coupling between the resonators is also restricted. There is a need for an electrode structure that can reduce the sexual coupling.

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

The present invention solves the above problems and provides a dielectric filter having a small capacitive coupling, that is, mainly an inductive coupling, with a simple structure and manufacturing process.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above problems by disposing a conductor film connected to an outer conductor inside a dielectric block and grounding the conductor film. .

That is, a flat second dielectric substrate is adhered on 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 groove, and the outer conductor is formed on the non-bonded surface of the first dielectric substrate and the second dielectric substrate 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 open end faces of, at least one surface of the dielectric substrate to which the dielectric substrate is bonded is It is characterized in that it has a conductor pattern extending in the direction and connected to the ground potential at the open end face.

A conductor film can be formed from the conductor pattern exposed on the open end face to the outer conductor to connect the conductor pattern to the ground potential.

[0011]

Since the conductor pattern grounded on the open end face side of the resonator is formed, capacitive coupling can be reduced, and the passband characteristic can be adjusted by adjusting the capacitance according to its size, shape or position. You can

[0012]

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

FIG. 2 is a perspective view showing a state before assembly of the dielectric filter according to the present invention. Two parallel grooves
A flat second dielectric substrate (22) is adhered to the side of the first dielectric substrate (21) having the concave groove (24) with glass or the like. This forms a block of dielectric with two parallel through holes. In the present invention, the conductor pattern 26 is previously formed on the adhesive surface of the dielectric substrate. The conductor pattern 26 is formed so as to extend from the edge portion of the dielectric substrate 21 which is the open end surface toward the edge which is the short-circuited end surface, and is formed on the surface of the dielectric substrate 21 between the two concave grooves 24.

FIG. 1 is a perspective view showing a dielectric filter according to the present invention after a first dielectric substrate and a second dielectric substrate are bonded and a conductor film is formed. Dielectric substrate 21 of FIG.
2 has a structure in which two through holes 15 are formed in a dielectric block formed by adhering a dielectric substrate 12 corresponding to the dielectric substrate 22 similarly to the dielectric substrate 11 corresponding to. This through hole
An inner conductor is formed on the inner surface of the inner part 15, and an outer conductor 17 is formed on the outer peripheral surface parallel to the extending direction of the through hole 15.
Although not shown in the figure, a short-circuit conductor is formed on one end face of the through hole 15 which is open, and a dielectric filter of ¼ wavelength TEM resonance is constituted.

The conductor pattern 26 formed on the joint surface shown in FIG. 2 is connected to the conductor film 13 at the open end surface. The conductor film 13 is connected to the outer conductor 17, whereby the conductor pattern 26 is electrically connected to the outer conductor 17 and is connected to the ground potential. The terminal electrode 18 is formed not only on the end surface parallel to the extending direction of the through hole 15 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
18 must be insulated from the outer conductor.

In the example of FIG. 2, the conductor pattern 26 is formed on the side of the dielectric substrate 21 having the concave groove, but when actually manufactured, as shown in FIG. 3, a flat dielectric substrate 32 is formed. It is easier to manufacture by forming on the surface of. At this time, the conductor film 36 for adjusting the coupling between the resonators and the conductor pattern 39 serving as an electrode for input / output coupling may be formed together.

Although the above example adjusts the coupling of two resonators, it can be similarly applied to a dielectric filter having three or more resonators.

FIG. 4 is an explanatory diagram of characteristics of the dielectric filter according to the present invention. The first dielectric substrate with a thickness of 1.8 mm and the second dielectric substrate with a thickness of 0.9 mm are bonded together, and the center spacing of the grooves is 2.5 mm, the width is 1 mm, and the depth is 0.9 mm. This is an example of a dielectric filter with open end face dimensions of 2.7 mm × 6.5 mm. The size from the open end face to the short-circuited end face depends on the center frequency, but in the 1500MHz band it is about 9.5m.
m. By forming a predetermined electrode with this size, a dielectric filter having a center frequency of 1575.4 MHz and an insertion loss of about 2 dB was obtained. When the conductor pattern that weakens the capacitive coupling between the resonators is not formed, the attenuation characteristics on the low band side and the high band side of the pass band are substantially symmetrical, whereas as shown in the figure, according to the present invention. In the dielectric filter, the attenuation characteristic on the high frequency side of the pass band is steep.

[0019]

According to the present invention, it becomes easy to obtain a dielectric filter having weak capacitive coupling between resonators, that is, mainly inductive coupling, and the frequency band pass characteristic is adjusted accordingly. be able to. 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.

[Brief description of drawings]

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

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

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

FIG. 4 is an explanatory diagram of characteristics of a dielectric filter according to the present invention.

[Explanation of symbols]

 11, 21: (First) dielectric substrate 12, 22, 32: (Second) dielectric substrate 26, 36: Conductor pattern

Claims (2)

[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 non-bonded surface of the first dielectric substrate and the second dielectric substrate 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 open end faces of, at least one surface of the dielectric substrate to which the dielectric substrate is bonded is A dielectric filter having a conductor pattern that extends in a direction and is connected to a ground potential at an open end surface. 2. The dielectric filter according to claim 1, further comprising a conductor film for connecting the outer conductor and the conductor pattern on the open end surface.