JP2002135003A - Waveguide-type dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate discontinuity between the signal lines of a wiring board and the input/output electrodes of a waveguide-type dielectric filter so as to reduce the dielectric filter in reflection or radiation loss. SOLUTION: Conductor patterns 13 and 14 extending inwards from the edges of a base are used as input/output electrodes and connected to microstrip lines or coplanar lines. The conductor films 13 and 14 are extended to the edge of the edge face of a dielectric body, and the dielectric body is exposed at the edge face where the conductor films 13 and 14 are brought into contact. The tongue-shaped conductor films 13 and 14 serve as input/output electrodes and are connected to the microstrip lines or coplanar lines which are of the same width with the conductor films and formed on a wiring board. The dielectric body is partly exposed around the conductor films 13 and 14, and the other surface of the dielectric body containing the connected parts is all covered with a conductor film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type dielectric filter, and more particularly to a structure of an input / output electrode thereof. The present invention relates to a resonator constituting the filter and an input / output structure that can be used also for a duplexer or the like using the filter.

[0002]

2. Description of the Related Art As a filter used in a frequency band of several GHz or more, a waveguide type dielectric filter which obtains desired characteristics by coupling a plurality of resonators each having a rectangular parallelepiped dielectric covered with a conductor film has been used. It is under consideration and is approaching the stage of practical application. Since the conventional waveguide has a structure in which the inside of the waveguide is filled with a dielectric, the size can be reduced.

However, in this type of waveguide type dielectric filter, the coupling structure of input / output terminals is a major problem. Heretofore, as shown in FIG. 11, one having a through hole formed in a dielectric, and one having an input / output conductor pattern formed on the side surface of the dielectric as shown in FIG. 12, have been proposed. I have.

However, in such an input / output coupling structure, the connection portion has a large discontinuity with the line on the circuit board, and particularly in a high frequency band of 10 GHz or more, loss due to reflection or radiation at the discontinuous portion. However, there is a problem that it is not suitable for practical use. Although it is conceivable to employ a shield structure for reducing radiation and reflection, there arises a problem of an increase in man-hours and costs due to an increase in the number of parts.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when a waveguide type dielectric filter is mounted on a circuit board, the discontinuity between the input / output terminal electrodes of the filter and the signal lines on the board is minimized. And means for reducing a loss caused by reflection and radiation of an electromagnetic field at an input / output unit. Moreover, it is realized with a simple electrode structure.

[0006]

According to the present invention, an input / output electrode of a waveguide type dielectric filter of a signal line on a circuit board and an input / output electrode of the waveguide type dielectric filter have the same shape. The above object is achieved by forming a conductor pattern.

That is, in a waveguide-type dielectric filter in which a plurality of rectangular parallelepiped dielectric resonators are connected and input / output electrodes are provided at the resonators at both ends, the same bottom surface of the resonators at both ends is provided.
An input / output terminal electrode is provided by a tongue of a conductive film that reaches the side from a position away from one side and has a dielectric exposed on both sides, and a portion of the side surface in contact with the side that contacts the tip of the tongue has a dielectric. It is characterized in that a conductive film is formed on the entire surface of the dielectric material, excluding the periphery of the input / output electrodes and the connection portion.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION On a bottom surface of an input / output stage of a waveguide type dielectric filter, a microstrip similar to a signal and a line provided on a (printed) circuit board on which the waveguide type dielectric filter is mounted. A line-shaped or coplanar line-shaped electrode pattern is formed, and this conductor pattern is terminated at the bottom surface. Thereby, while being connected to the signal line of the circuit board, the signal supplied from the circuit board is coupled with the resonance mode inside the waveguide type dielectric filter.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. It is a dielectric having a relative dielectric constant of 9.0 and two rectangular parallelepiped dielectrics 11 and 12 of 5.2 mm × 5.2 mm × 2.5 mm connected by the same dielectric having a width of 2.3 mm and a length of 1.0 mm. Conductive films 13 and 14 each having a width of 1.0 mm and a length of 1.4 mm from the side of the end face are formed on the same bottom surface, and a dielectric material having a width of 0.5 mm is exposed on both sides thereof.

The conductor films 13 and 14 extend to the sides of the end faces of the dielectric, and the portions of the end faces in contact with the sides that contact the conductor films 13 and 14 are also exposed. These tongue-shaped conductor films
Input and output electrodes 13 and 14 are connected to microstrip lines or coplanar lines of the same width formed on the wiring board. The dielectric is exposed in a part of the periphery of the conductor films 13 and 14, but the other surfaces are covered with the conductor film including the connection portions.

FIG. 2 shows the characteristics of the waveguide type dielectric filter shown in FIG. Center frequency 12.97GHz, 3dB bandwidth 4
A waveguide-type dielectric filter with a low loss of 50 MHz and an insertion loss of 0.6 dB was obtained.

In order to increase the bandwidth of the filter, it is necessary to increase the coupling between the resonator and the external circuit. The coupling with the external circuit can be adjusted by changing the dimensions of the input / output electrode pattern. Increasing the gap around the input / output electrode pattern (exposed portion of the dielectric) can increase the external coupling and widen the bandwidth.

FIG. 3 is a perspective view showing another embodiment of the present invention. Almost the same structure as above, but 5.2mm × 4.8mm ×
Two 2.5mm rectangular parallelepiped dielectrics 31 and 32 are 2.3mm wide and long
These are connected by the same dielectric of 1.0 mm. Conductor films 33 and 34 that are 1.0 mm wide and 1.4 mm long from the edge of the end face
Are formed, and on both sides thereof, a dielectric is exposed with a width of 1.0 mm. As described above, the dielectric is exposed at a part around the conductor films 33 and 34, but the other surface is covered with the conductor film including the connection part.

FIG. 4 shows the characteristics of the waveguide type dielectric filter shown in FIG. Center frequency 13.12GHz, 3dB bandwidth 9
A waveguide-type dielectric filter with a low loss of 80 MHz and an insertion loss of 0.5 dB was obtained. Thus, the bandwidth is more than doubled by widening the gap between the input and output electrodes.

The waveguide type dielectric filter may be connected with three or more resonators in order to obtain a desired band-pass characteristic. FIG. 5 is a perspective view showing another embodiment of the present invention.
Two rectangular parallelepiped dielectrics 51 and 52 of 5.2mm × 5.2mm × 2.5mm and a dielectric 55 of 5.2mm × 5.0mm × 2.5mm interposed between them have the same 2.3mm width and 1.0mm length These are connected by a dielectric. On the same bottom surface, conductor films 53 and 54 having a width of 1.0 mm and a length of 1.4 mm from the side of the end face are formed, and on both sides thereof
The dielectric is exposed with a width of 0.5 mm.

FIG. 6 shows the characteristics of the waveguide type dielectric filter shown in FIG. Center frequency 13.01GHz, 3dB bandwidth 4
A waveguide-type dielectric filter having a low loss was obtained in the same manner as in the above-described embodiment, at 00 MHz and an insertion loss of 0.9 dB. Since the number of stages is increased, the attenuation characteristics outside the pass band are steep.

As shown in FIGS. 7A to 7F, the position and direction of the input / output electrode can be arbitrarily selected.
However, it is necessary to form them on the same surface (bottom surface). Further, as shown in FIG. 8, the input / output electrode portion may be protruded.

The mounting structure of the waveguide type dielectric filter according to the present invention will be described. 9A and 9B show a state in which a waveguide type dielectric filter 90 is embedded in a printed circuit board 96, wherein FIG. 9A shows a state before mounting, FIG. 9B shows a state after mounting, and FIG.
93 and 94 and the coplanar line 97 are soldered so as to be on the same plane. In this case, there is an advantage that the continuity of the line is kept high.

Another mounting structure of the waveguide type dielectric filter according to the present invention will be described. FIG. 10 shows a printed circuit board 106.
On which the waveguide type dielectric filter 100 is mounted, (a)
FIG. 2B shows a state before mounting, and FIG. 2B shows a state after mounting, in which the input / output electrodes and the coplanar line 107 are soldered. In this case, discontinuity of the line occurs, but there is an advantage that assembly is easy. The signal line may use a microstrip line.

[0020]

According to the present invention, since the input / output electrodes of the circuit board on which the signal lines are extended extend into the dielectric resonator and are terminated, the input / output signals of the TEM mode are provided on the bottom surface. Flows. Due to this current, the magnetic field induced inside the waveguide resonator is coupled with the magnetic field of the fundamental resonance mode of the waveguide resonator, resulting in the coupling between the external circuit and the resonator. .

As a result, since the signal line and the input / output electrode are on the same surface and have the same width, continuity between the signal line of the circuit board and the input / output terminal electrode of the filter is provided.
It is possible to suppress reflection and radiation of a high-frequency signal generated in a discontinuous portion, and to reduce loss.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of characteristics of the filter of FIG.

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

FIG. 4 is an explanatory diagram of characteristics of the filter of FIG. 3;

FIG. 5 is a perspective view showing another embodiment of the present invention.

FIG. 6 is an explanatory diagram of characteristics of the filter of FIG. 5;

FIG. 7 is a bottom view showing an example of an input / output electrode;

FIG. 8 is a perspective view showing another embodiment of the present invention.

FIG. 9 is a perspective view showing another embodiment of the present invention.

FIG. 10 is a perspective view showing another embodiment of the present invention.

FIG. 11 is a perspective view of a conventional dielectric filter.

FIG. 12 is a perspective view of a conventional dielectric filter.

[Explanation of symbols]

 11, 12, 31, 32, 51, 52, 55: dielectric resonators 13, 14, 33, 34, 53, 54, 93, 94: input / output electrodes 97, 107: coplanar line

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Meiji Miyashita 828 Hinohara, Tamagawa-mura, Hiki-gun, Hiki-gun, Saitama F-term in the Tamagawa Plant of Toko Co., Ltd. 5J006 HC01 HC12 HC23 HC24 JA01 LA07 LA11 NA08 ND01 NE13 NE14

Claims (3)

[Claims] 1. A waveguide type dielectric filter in which a plurality of rectangular parallelepiped dielectric resonators are connected and input / output electrodes are provided at the resonators at both ends. Equipped with input / output terminal electrodes made of conductive film tongues that reach the side from a distant position and the dielectric is exposed on both sides, the part of the side surface that touches the side touches the tip of the tongue, the dielectric is exposed And a conductor film formed on the entire surface of the dielectric except for the periphery of the input / output electrodes and the connection portion. 2. The waveguide type dielectric filter according to claim 1, wherein the input / output electrodes are connected to the microstrip line of the wiring board. 3. The waveguide type dielectric filter according to claim 1, wherein the input / output electrode is connected to a coplanar line of the wiring board.