JPH0135526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a small high frequency filter device as a band pass filter used in high frequency radio equipment.

Conventional configurations and their problems In recent years, as high-frequency mobile radio technology has been put into practical use, there has been a desire to make radio equipment thinner, and along with this, there has been a need to make the bandpass filters that are components smaller. There is. Conventionally, low-cost, high-quality, high-frequency compact filter devices that use a dielectric coaxial resonator as a resonator have been widely used.

A high frequency small filter device as a band pass filter using a conventional dielectric coaxial resonator will be described below with reference to the drawings. Figure 1 shows the internal structure of a conventional small high frequency filter device.
a, 1b are dielectric coaxial resonators, 2a, 2b, 2
c, 2d are connection terminals, 3a, 3b are input/output terminals,
4 is a dielectric substrate, 5a and 5b are open end surfaces of dielectric coaxial resonators 1a and 1b, and 6a and 6b are terminal surfaces of dielectric coaxial resonators 1a and 1b. FIG. 2 is a detailed diagram of the dielectric substrate shown in FIG.
a, 7b, 10a, 10b, 11a, 11b are electrodes, 8a, 8b, 9a, 9b, 9c, 9d
is a through hole.

In the small high-frequency filter device configured as described above, the dielectric coaxial resonators 1a and 1b are formed by forming a dielectric material into a cylindrical shape, and printing a thick film of silver conductor on the outer peripheral surface, inner peripheral surface, and one end surface of the dielectric material. It is made with
Works as a λ/4 type resonator. The electrodes 10a and 10b on the dielectric substrate 4 are connected to the dielectric coaxial resonator 1 by connecting terminals 2a and 2d inserted into the through holes 9a and 9b.
It is connected to the inner peripheral surface conductors of a and 1b, and the through hole 8
An input/output capacitor is formed between opposing surfaces of electrodes 7a and 7b connected to input terminals 3a and 3b through a and 8b. Further, the electrodes 11a and 11b on the dielectric substrate 4 are connected to the inner circumferential surface conductors of the dielectric coaxial resonators 1a and 1b by connecting terminals 2b and 2c inserted into the through holes 9a and 9c, respectively. A coupling capacitor is formed between the facing end faces. The high-frequency compact filter device formed in this way acts as a high-frequency bandpass filter. However, in the conventional configuration as described above,
The total height of the filter is affected not only by the total length of the dielectric coaxial resonators 1a and 1b, but also by the thickness of the dielectric substrate 4 and the lengths of the connection terminals 2a, 2b, 2c, and 2d, and the demand for thinner The problem was that it was not possible to provide a sufficient answer.

OBJECTS OF THE INVENTION An object of the present invention is to provide a small high frequency filter device that can keep the overall height of the device itself as low as possible.

Structure of the Invention The small high frequency filter of the present invention has a dielectric substrate provided with electrodes so as to form a capacitor between opposing surfaces and end surfaces, and has a through hole formed in a portion other than the electrodes, and a dielectric substrate is formed in the through hole. It is constructed so that the open end of the coaxial resonator is fitted into it, and this makes it possible to shorten the total height of the filter device itself to the same extent as the total length of the dielectric coaxial resonator. be.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a front view showing the internal structure of a small high frequency filter device according to an embodiment of the present invention, and FIG. 4 is a side view thereof. In FIGS. 3 and 4, 12a and 12b are dielectric coaxial resonators, and 13
a and 13b are the termination surfaces of the dielectric coaxial resonators 12a and 12b, and 14a and 14b are the dielectric coaxial resonators 12
The open end faces of a and 12b and 15 are dielectric substrates. In addition, FIG. 5 shows the dielectric substrate 1 in FIG.
5, 16a, 16b are input/output terminals, 17a, 17b, 17c, 17d are connection terminals, 18a, 18b, 19a, 19b, 20a,
20b electrode, 21a, 21b are through holes, 22a,
22b, 22c, and 22d are through holes.

In the small high-frequency filter device of this embodiment configured as described above, a dielectric material is formed into a cylindrical shape and a silver conductor is printed as a thick film on the outer circumferential surface, inner circumferential surface, and one end surface of the dielectric material. Dielectric coaxial resonator 1
2a and 12b are inserted into through holes 21a and 21b provided in the dielectric substrate 15, and function as λ/4 type coaxial resonators. Input/output terminals 16 inserted into through holes 22a, 22b of dielectric substrate 15
electrodes 18a, 18b connected to a, 16b;
Connection terminals 17 inserted into through holes 23a and 23d
dielectric coaxial resonators 12a, 12 by a, 17d
Electrodes 19a and 19b connected to the inner peripheral surface conductor of b
and form an input/output capacitor between their opposing surfaces. Also, the connection terminal 1 inserted into the through hole 23b
The electrode 2a is connected to the inner circumferential surface conductor of the dielectric coaxial resonator 12a by the electrode 2a connected to the inner circumferential surface conductor of the dielectric coaxial resonator 12b by the connecting terminal 17c inserted into the through hole 23c. The electrode 2b is
A coupling capacitor is formed between the opposing end surfaces. The high-frequency compact filter device formed in this way acts as a high-frequency bandpass filter.

As described above, according to this embodiment, the dielectric substrate 1
By inserting the dielectric coaxial resonators 12a and 12b into the through-holes 21a and 21b provided in 5, the dielectric coaxial resonators 12a and 12b were integrated with the dielectric substrate 15, so that the small high frequency filter The device can be made thinner.

In the above embodiment, the dielectric coaxial resonator has a coaxial cylindrical shape, but the dielectric coaxial resonator may have any coaxial shape. For example, a coaxial truncated cone shape can be used. Furthermore, although two dielectric coaxial resonators are used in this embodiment, any number of dielectric coaxial resonators may be used, and the structure can be similar to that of this embodiment.

Effects of the Invention As is clear from the above description, the present invention has a method of fitting a dielectric coaxial resonator into a through hole provided in a dielectric substrate and integrating the dielectric coaxial resonator and the dielectric substrate. Because of this configuration, the thickness of the dielectric substrate 15 can be ignored and the height of the connecting portion between the dielectric coaxial resonator and the dielectric substrate can be suppressed to the minimum dimension. As a result, an excellent effect can be obtained in that a small high-frequency filter device serving as a high-frequency band-pass filter can be made thinner.

[Brief explanation of drawings]

FIG. 1 is a front view of the main parts of a conventional small high frequency filter device, and FIG. 2 is a dielectric substrate used in the filter device, where a is a top view, b is a front view, c is a rear view, and FIG. Figure 3 is a front view of the main parts of a small high frequency filter device in an embodiment of the present invention;
Figure 4 is a side view of the main parts of the filter device, Figure 5
The figures show a dielectric substrate used in the same filter device; a is a top view, b is a front view, and c is a rear view. 12a, 12b...dielectric coaxial resonator, 15...
...Dielectric substrate, 18a, 18b, 19a, 19
b, and 20a, 20b...electrode, 21a, 21
b...Through hole.

Claims (1)

[Claims] 1 Electrodes are provided on both sides of a dielectric substrate so as to form a capacitor between opposing surfaces and gaps, a through hole is provided in the part of the dielectric substrate excluding the electrodes, and a dielectric coaxial resonator is inserted into the through hole. The open end sides are fitted together, and a terminal connected to the inner peripheral surface conductor of the dielectric coaxial resonator projects from the open end side of the dielectric coaxial resonator, and the projecting terminal and the electrode of the dielectric substrate A high-frequency small filter device characterized by being connected to.