JPH0624283B2 - Dielectric filter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric filter often used in the VHF band, the UHF band, and the microwave band.

[Conventional technology]

FIG. 6 is a transverse sectional view showing a conventional dielectric filter disclosed in, for example, Japanese Utility Model Laid-Open No. 57-158203, and FIG. 7 is a longitudinal sectional view thereof, in which 1 is an outer conductor which also serves as a case. A main body 2, an outer conductor cover that covers the opening surface of the outer conductor main body 1, and a plurality of outer conductor lids 3 are arranged in the outer conductor main body 1 with their lengths set to approximately ¼ wavelength, and each of them is external at one end thereof. An inner conductor 4 short-circuited to the bottom of the conductor body 1 and the other end being an open end, 4 is a dielectric closely arranged around each inner conductor 3, and 5 is in contact with the outer conductor body 1 of the dielectric 4. Conductor films closely attached to the portions, 6a to 6f are resonators constituted by the outer conductor main body 1, the outer conductor lid 2, the inner conductor 3 and the dielectric 4 to which the conductor film 5 is closely attached, and 7 is the resonator 6a. , 6f are closely arranged on the surface of the dielectric 4 near the inner conductor 3 and are coupled to the inner conductor 3. And are input and output coupling pattern,
Reference numeral 8 denotes a coupling pattern which is closely arranged on the surface of the dielectric 4 near the inner conductor 3 forming the resonators 6a, 6b, 6e and 6f, and is coupled to the inner conductor 3. Coaxial cable as a connection line to connect, 1
Reference numerals 0 and 11 are input / output terminals connected to the input / output coupling pattern 7. Reference numeral 12 is adjustably screwed to the outer conductor lid body 2 corresponding to each inner conductor 3, and its end is an open end of the corresponding inner conductor 3. It is a frequency adjustment screw facing the.

Next, the operation will be described. The resonators 6a to 6f are adjacent to each other and are coupled by magnetic field coupling, and the coupling amount is adjusted by the distance between the adjacent inner conductors 3.
Further, the resonators 6a and 6f and 6b and 6e are coupled by a coaxial cable 9 via a coupling pattern 8 arranged on the surface of the dielectric 4 on the open end side of the inner conductor 3, and further, the input / output terminal 10, Reference numeral 11 is connected to the input / output coupling pattern 7 arranged on the inner conductor 3 open end side surface of the dielectric 4 of the resonator 6a or 6f, respectively, and is coupled to the resonator 6a or 6f. It is adjusted according to the size of the coupling pattern 8 or the input / output coupling pattern 7.

Now, assuming that all the resonators 6a to 6f are resonating at the same frequency, for example, ₀ by adjusting the length of the inner conductor 3 and the frequency adjusting screw 12, at the frequency ₀ , the resonance state is obtained. The resonators 6a to 6f are strongly coupled to each other, and the incident wave to the input / output terminal 10 is guided to the resonator 6a from the input / output coupling pattern 7, and is transmitted from the resonator 6f via the input / output coupling pattern 7. It is output from the input / output terminal 11. However, at frequencies other than ₀ , the resonator 6a
The coupling between ˜6f is very weak, and most of the electric power of the incident wave to the input / output terminal 10 or 11 is reflected.
As described above, the dielectric filters shown in FIGS. 6 and 7 have a function as a bandpass filter, and the resonators 6a and 6f and 6b and 6e which are not adjacent to each other have the coupling pattern 8 therebetween. Since they are coupled by the coaxial cable 9 and this coupling is an electric field coupling having a polarity different from that of the magnetic field coupling between the adjacent resonators, an attenuation pole is generated near the pass band,
It exhibits steep damping characteristics.

[Problems to be solved by the invention]

Since the conventional dielectric filter is configured as described above, the outer conductor main body 1 and the outer conductor lid 2 are provided with the inner conductor 3 and the frequency adjusting screw 12 and function as a case having a mechanically stable structure. In order to satisfy the requirements, a certain thickness is required, which hinders size reduction and weight reduction, and the outer conductor main body 1, outer conductor lid 2, inner conductor 3, frequency adjusting screw 4, dielectric 5 etc. are all separate parts. Therefore, not only the number of parts is large and the manufacturing and assembling become complicated, but also regarding the resonators 6a and 6f, the input / output coupling pattern 7 and the coupling pattern 8 are the dielectric 4
Since they are arranged close to each other on the same plane, there is a problem that they are coupled to each other and the out-of-band attenuation characteristics of the filter deteriorate.

The present invention has been made to solve the above-mentioned problems, and has a small number of parts, is easy to manufacture and assemble, and can be made compact and lightweight, and also has a good out-of-band attenuation characteristic. The purpose is to obtain a body filter.

[Means for solving problems]

The dielectric filter according to the present invention is a conductor film in which an inner conductor is in close contact with the inner peripheral surfaces of a plurality of through holes formed in the dielectric block, and the outer conductor is an outer periphery other than the opening surface of the through hole of the dielectric block. The inner conductor connecting means is formed on at least one of the flat surface and the bottom surface of the dielectric block, and the input / output inner conductor is connected to the middle portion of the predetermined inner conductor. Is provided with electrostatic coupling means for electrostatically coupling with each of them, and the electrostatic coupling means are connected by a connection line.

[Action]

In the dielectric filter according to the present invention, the inner conductor and the outer conductor are formed of a conductor film that is in close contact with the dielectric block, and the filter function is realized by the action of the inner conductor coupling means provided on at least one of the flat surface and the bottom surface of the dielectric block. By doing so, the number of parts is reduced by integrating the inner conductor and outer conductor with the dielectric block to facilitate manufacturing and assembly, and it is possible to reduce the size and weight by eliminating the need for the outer conductor to function as a case. At the same time, the connection portion of the input / output inner conductor and the electrostatic coupling means are separated from each other by distance so that they are not coupled to each other, thereby preventing deterioration of the out-of-band attenuation characteristic.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. First
In FIG. 2 and FIG. 2, 8 is a coupling pattern as an electrostatic coupling means, 9 is a coaxial cable as a connecting line, which is equivalent to those of the prior art with the same reference numerals in FIGS. 6 and 7. is there. Further, 13 is a dielectric block made of a dielectric having a high dielectric constant, and 14 is one side surface of this dielectric block 13, for example, a front surface is opened to a back surface which is an opposite surface thereof in parallel with the plane and the bottom surface, A plurality of through holes arranged in parallel with the plane and the bottom,
Reference numeral 5 denotes an outer conductor formed of a conductor film which is arranged in close contact with the plane, bottom surface, left side surface, right side surface and back surface of the dielectric block 13, and 16 is arranged in close contact with the inner peripheral surface of each through hole 14. A conductive film, one end of which is a dielectric block 13
Seamlessly connected to the outer conductor 15 on the back surface of
Inner conductors 17 and 18, which together with the outer conductor 15 constitute one-quarter wavelength resonator of which one end is open and one end is short-circuited, 17 and 18 are connected to a portion between the open end and the short-circuit end of the inner conductor 16 arranged at both ends. An input / output inner conductor 19 for shunting a part of the current flowing through the conductor 16 is formed on the plane and bottom of the dielectric block 13 continuously in the direction perpendicular to the axial direction of the inner conductor 16 to form the outer conductor 15. A conductor film that is seamlessly connected to is closely arranged, and is a groove that acts as an inner conductor coupling means,
The coupling patterns 8 are arranged on the surfaces of the dielectric blocks 13 near the open end faces of the inner conductors 16 arranged at both ends, and are connected to each other by a coaxial cable 9.

Next, the operation will be described. This dielectric filter is 1 /
Since the open ends of the four-wavelength resonator are arranged on the same side, the mutual coupling between the inner conductors 16 cannot be normally obtained, but the provision of the groove 19 prevents the electromagnetic wave from being generated in that portion. Due to the action of the generated TM mode, the coupling between the inner conductors 16 is obtained, and the coupling amount depends on the depth of the groove 19 and the inner conductor 1.
It can be adjusted by a mutual distance of 6. Now, if all the inner conductors 16 resonate at the same frequency ₀ by adjusting the length of the inner conductors 16,
_{At 0} , each inner conductor 16 in the resonance state is strongly coupled to the adjacent inner conductor 16 or the input / output inner conductors 17 and 18, and is connected to the input / output terminal conductor (not shown) connected to the input / output inner conductor 17. The incident wave is guided to an input / output terminal (not shown) connected to the input / output inner conductor 18. However,
_At frequencies other than ₀ , the mutual coupling between the inner conductors 16 and the coupling between the inner conductors 16 and the input / output inner conductors 17 and 18 are very weak, and the incident wave to the input / output terminal connected to the input / output inner conductors 17 or 18 is very weak. Most of its power is reflected. As described above, the dielectric filter of the present invention has a function as a band pass filter, and the resonators that are not adjacent to each other are coupled by the coaxial cable 9 via the coupling pattern 8, and the coupling is performed by the adjacent resonators. Since the magnetic field coupling between the two is electric field coupling having different polarities, an attenuation pole is generated in the vicinity of the pass band, exhibits steep attenuation characteristics, and the input / output inner conductors 17 and 18 and the coupling pattern 8 are arranged with a distance therebetween. Because
They do not combine with each other to deteriorate the out-of-band attenuation characteristics of the filter.

In the above embodiment, the case where the continuous groove 19 is used as the inner conductor coupling means has been described, but it may be replaced by step 20 as shown in FIG. Also in this step 20, the conductor film seamlessly connected to the outer conductor 15 is closely arranged and continuously provided in the direction perpendicular to the axial direction of the inner conductor 16. This step 20 is generated in the electromagnetic field. By the action of the TM mode, the inner conductors 16 are coupled to each other to realize the function of the bandpass filter, and by the coupling by the coaxial cable 9 via the coupling pattern 8,
It realizes a steep and good attenuation characteristic outside the band.

Further, FIG. 4 is a perspective view showing still another embodiment of the present invention, and FIG. 5 is a longitudinal sectional view thereof, in which a capacitor is used instead of the coupling pattern as the electrostatic coupling means. In the figure, 21 is the capacitor, one electrode of which is directly connected to the open end of the inner conductor 16, and the coaxial cable 9 is connected to the other electrode of the capacitor 21. The operation of this embodiment is similar to that of the embodiment shown in FIGS. 1 and 2, and in this embodiment this capacitor 2
1 results in a larger bond than in the previous embodiment with bond pattern 8.

In the above embodiment, the case where four inner conductors are used and the inner conductor coupling means is provided on both the flat surface and the bottom surface of the dielectric block has been described, but the number of inner conductors may be four or more. Also, the inner conductor coupling means may be provided on only one of the flat surface and the bottom surface of the dielectric block, and a coaxial cable as a connection line may also have a thick film or the like on the inner conductor open end surface of the dielectric block. It is also possible to substitute the conductor pattern formed in 1., and in any of these cases, the same effect as that of the above-described embodiment can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the inner conductor and the outer conductor are formed of the conductor film in close contact with the dielectric block, the inner conductors are coupled to each other by the inner conductor coupling means, and the input and output inner conductors are opened. Since the electrostatic coupling means is arranged near the open end of the inner conductor by connecting it in the middle of the end and the short-circuited end, it is not necessary to give the outer conductor the function of the case, and the size and weight can be reduced. No need for frequency adjustment screws, etc., the parts are reduced to only the dielectric block in which the inner conductor and the outer conductor are closely arranged and the connection line, which not only simplifies manufacturing and assembly but also connects the input and output inner conductors. Since the position and the position where the electrostatic coupling means are arranged are separated from each other in distance, there is an effect that a dielectric filter having steepness and good out-of-band attenuation can be obtained. Further, since the inner conductor coupling means is provided on at least one of the plane and the bottom surface of the dielectric block in the direction perpendicular to the axial direction of the inner conductor, the resonance frequency of the higher mode can be shifted from an integral multiple of the fundamental mode, There is an effect that the amount of attenuation with respect to the resonance frequency of the higher-order mode can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing a dielectric filter according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view thereof, FIG. 3 is a perspective view showing another embodiment of the present invention, and FIG. 5 is a perspective view showing still another embodiment of the present invention, FIG. 5 is a longitudinal sectional view thereof, FIG. 6 is a transverse sectional view showing a conventional dielectric filter, and FIG. 7 is a longitudinal sectional view thereof. 8 is an electrostatic coupling means (coupling pattern), 9 is a connection line (coaxial cable), 13 is a dielectric block, 14 is a through hole,
Reference numeral 15 is an outer conductor, 16 is an inner conductor, 17 and 18 are input / output inner conductors, 19 is an inner conductor coupling means (groove), 20 is an inner conductor coupling means (step), and 21 is an electrostatic coupling means (capacitor). In the drawings, the same reference numerals indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Shumi Ishida, 1-1 1-1 Ofuna, Kamakura-shi, Kanagawa Mitsubishi Electric Corporation, Information Technology Lab. (72) Inventor, Fumio Takeda 5-chome, Ofuna, Kamakura-shi, Kanagawa No. 1 Mitsubishi Electric Corporation Information Electronics Laboratory

Claims (5)

[Claims] 1. A plurality of through holes formed in parallel with a plane and a bottom surface from one side surface are in close contact with a dielectric block arranged in parallel with the plane and the bottom surface and an inner peripheral surface of each of the through holes. An inner conductor made of an arranged conductor film, and a conductor film closely attached to the outer peripheral surface of the dielectric block except one surface where the through hole is open, and the inner conductor and one end thereof. An outer conductor that is seamlessly connected in, an input / output inner conductor that is connected to a portion between a predetermined open end and a short end of the inner conductor, and at least one of the plane and the bottom surface of the dielectric block. And an inner conductor coupling means in which a conductor film continuously provided in a direction perpendicular to the axial direction of the inner conductor and closely connected to the outer conductor is closely arranged, and the input / output inner conductor is connected. Electrostatically with the open end of the inner conductor Dielectric filter comprising a capacitive coupling means are engaged, and a connection line for connecting mutually said electrostatic coupling means. 2. As the inner conductor coupling means, a groove is provided in which a conductor film seamlessly connected to the outer conductor is closely arranged and is continuously provided in a direction perpendicular to the axial direction of the inner conductor. The dielectric filter according to claim 1, which is characterized in that. 3. A step in which a conductor film seamlessly connected to the outer conductor is closely arranged as the inner conductor coupling means, and the step is continuously provided in a direction perpendicular to the axial direction of the inner conductor is used. The dielectric filter according to claim 1, which is characterized in that. 4. A coupling pattern arranged on the surface of a dielectric block near the open end of the inner conductor is used as the electrostatic coupling means. The dielectric filter according to any one of 1. 5. A capacitor having one electrode connected to the open end of the inner conductor as the electrostatic coupling means, according to any one of claims 1 to 3. A dielectric filter according to item.