JPS6330002A - Strip line filter - Google Patents

Abstract

PURPOSE:To miniaturize the entire circuit board unit by providing a ground electrode to one of major face of a dielectric board, providing plural resonance electrodes to the other face and providing a resonance electrode also to the side face so as to miniaturize the shape of a strip line filter and constitute the filter of chip type. CONSTITUTION:Both ends of the ground electrode 2 of the major surface of the dielectric base 1 are prolonged up to both sides of the other major surface 1a via both the opposed side faces of the dielectric base 1 to form a couple of prolonged parts 2a, 2b. For example, one resonance electrode 4 is led from one prolonged part 2a to the major surface 1a in the direction of the opposed prolonged part 2b and the resonance electrodes 3, 5 are led to the side surfaces 1b, 1c. Further, an input/output terminal 6 is connected on the way of the resonance electrodes 3, 5 of both the side faces. For example, two resonance electrodes 8, 9 are led from the other prolonged part 2b in the direction of the prolonged part 2a and arranged to each gap of resonance electrodes 3-5. Moreover, a metallic plate 10 being a ground terminal is fitted to the ground electrode 2. Thus, the surface mount of components is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stripline filter used as a bandpass filter, for example. A stripline filter as shown in the figure is known.

The stripline filter shown in this figure is a five-stage ink-digital type, and the reference numeral 20 in the figure is a rectangular flat dielectric substrate, and one main surface of this dielectric substrate 20 (
In the figure, a ground electrode 21 is formed on the entire surface (back side). Both ends of this ground electrode 21 are extended to both sides of the other main surface 20a of the dielectric substrate Vi20 through both opposing side surfaces of the dielectric substrate 20, and form a pair of extensions 21a.
.

21b is formed.

Three resonant electrodes 22 to 24 are drawn out in parallel from one extending portion 21a to the rear of the opposing extending portion 21b. Further, from each of the resonant electrodes 22, 24 arranged on both sides, terminal electrodes 25.
26 is extended.

Two resonant electrodes 27 and 28 are drawn out from the other extended portion 21b in the direction of the opposing extended portion 21a, and the resonant electrode 2
They are arranged in each of the gaps 2 to 24.

(C) Problems to be Solved by the Invention In bandpass filters using such stripline filters, the attenuation characteristics are improved by increasing the number of filters, for example.

However, increasing the number of filters increases the overall outer diameter of the bandpass filter and increases the area required for installation. Furthermore, microwave filters have the problem of increased leakage of electromagnetic waves to the outside.

The present invention aims to solve these conventional problems and provide a stripline filter that can reduce the outer diameter and reduce leakage of electromagnetic waves to the outside.

(Means for solving the d1 problem) This invention provides a ground electrode on one main surface of a dielectric substrate, a plurality of resonant electrodes on the other main surface, and
A feature is that a resonant electrode is also provided on the side surface of this dielectric substrate.

(e) Effect With the above configuration, resonance regions are formed on the side surfaces as well as the main surface of the dielectric substrate, so even if the area of the main surface is reduced, it is possible to provide a large number of resonant electrodes as a whole. can. Therefore, it is possible to downsize the entire filter.

(F1 Embodiment FIG. 1 is a perspective view showing the external appearance of a stripline filter according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof.

In the figure, reference numeral 1 denotes a rectangular flat dielectric substrate made of ceramics. One main surface of this dielectric substrate 1 (
In the figure, a ground electrode 2 is formed on the front (back side).

Both ends of this ground electrode 2 are extended to both sides of the other main surface 1a of the dielectric substrate 1 through both opposing side surfaces of the dielectric substrate 1, forming a pair of extensions 2a and 2b. has been done.

One resonance electrode 4 is drawn out from one extension part 2a to the main surface 1a in the direction of the opposing extension part 2b, and one resonance electrode 3.5 is drawn out to each of the side surfaces 1b and lc. ing. In addition, resonance electrodes 3 arranged on both surfaces.
An input/output terminal 6 having a cross-sectional shape is connected to the middle of the terminal 5 . This input/output terminal is attached by soldering or baking silver paste at the part indicated by A in the figure.

Two resonance electrodes 8 and 9 are drawn out from the other extension part 2b to the main surface in the direction of the opposing extension part 2b, and the resonance electrode 3
A metal plate 10 used as a ground terminal is attached to the ground electrode 2 disposed in each of the gaps 5 to 5. This attachment is carried out in the same manner as the input/output terminal 6 described above, by soldering the portion shown by B in the figure or by baking a paste. Since the terminals are taken out to the side of the bottom surface of the element in this way, it becomes easy to surface-mount the element on a circuit board.

In the above embodiment, since the resonant electrodes are provided on the side surface of the dielectric substrate, it is necessary to increase the thickness of the dielectric substrate to some extent, but generally speaking, as the thickness of the dielectric substrate increases, the coupling between the resonant electrodes is reduced. It gets expensive. In order to achieve a coupling degree similar to that of conventional filters, a substrate having the following structure can be used.

FIG. 3 shows another embodiment of the present invention, and is shown in correspondence with the sectional view shown in FIG. 2.

As is clear from the figure, a recess is provided in the center of one main surface (back side in the figure) of the dielectric substrate, and a ground electrode 2 is formed on the front surface along this recess. By forming the concave portion on one main surface of the dielectric substrate in this manner, the degree of coupling between the respective resonant electrodes can be made comparable to that of the conventional method.

Note that although the above embodiment is an example of an ink digital type stripline filter, the present invention is not limited to this, and can also be applied to other types of stripline filters such as a combline type.

(A) Effects of the invention As described above, according to the present invention, the shape of the stripline filter can be reduced in size, so a chip-type filter mounted on the surface of a circuit board can be constructed. The entire circuit board unit using the knobline filter can be downsized.

[Brief explanation of drawings]

1 and 2 show an embodiment of the invention, with FIG. 1 being a perspective view and FIG. 2 being a sectional view. Further, FIG. 3 is a sectional view showing another embodiment. FIG. 4 is a diagram showing an example of a conventional stripline filter. 1-dielectric substrate, la, ld-main surface of dielectric substrate, lb, lc-side surface of dielectric substrate, 2-ground electrode, 3-5, 8.9-resonant electrode.

Claims (1)

[Claims] (1) In a stripline filter in which a ground electrode is provided on one main surface of a dielectric substrate and a plurality of resonant electrodes are provided on the other main surface, the resonant electrodes are provided on the side surface of the dielectric substrate. A stripline filter featuring: