JPH0733441Y2 - High frequency filter - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a high-frequency filter which is often used in a relatively high frequency band, particularly in the VHF band, the UHF band and the microwave band.

[Conventional technology]

FIG. 3 is a view showing a conventional high-frequency filter disclosed in, for example, Japanese Patent Laid-Open No. 55-143801, in which FIG. 3 (a) is a partially cutaway plan view and FIG. 3 (b) is a vertical front view. Is. In the figure, 1,2
Is an outer conductor, 3 is an inner conductor, 4 is a frequency adjusting screw, 5 is a dielectric, 6 is an input / output loop, and P ₁ and P ₂ are input / output terminals.

One end of the inner conductor 3 is connected to the outer conductor 1 to form a short-circuited end,
The other end is an open end, and a capacitive load is provided by the frequency adjusting screw 4. Since the length of the inner conductor 3 is not more than 1/4 wavelength due to the effect of electrostatic capacitance, the inner conductors 3 are mainly coupled to each other by magnetic field coupling. The amount of coupling is adjusted by the distance between the two inner conductors 3.
Further, since the input / output loop 6 is arranged in parallel with and close to the inner conductor 3 and the length of the section arranged in parallel is 1/4 wavelength or less, the coupling is mainly magnetic field coupling.

Next, the operation will be described. Now, assuming that all the inner conductors 3 resonate at the same frequency f ₀ by adjusting the length of the inner conductors 3, the inner conductors 3 that are in a resonance state at the frequency f ₀ are strongly coupled to each other and enter. It is also strongly coupled to the output loop 6, and the incident wave to the input / output terminal P ₁ is guided to the input / output terminal P ₂ . However, at frequencies other than the frequency f ₀ , the inner conductor 3
Are very weakly coupled to each other and to the input / output loop 6, and most of the electric power of the incident wave to the input / output terminal P ₁ or P ₂ is reflected. As described above, the conventional high frequency filter shown in FIG. 3 has a function as a band pass filter.

[Problems to be solved by the invention]

Since the conventional high-frequency wave filter is configured as described above, a dielectric material having a large relative permittivity is used as the dielectric material 5 and a capacitive load is provided by the frequency adjusting screw 4 to reduce the size of the machine. The outer conductors 1 and 2 must have a certain thickness to mount the frequency adjustment screw, and there is a limit to the miniaturization. Since the individual components such as 3, the frequency adjusting screw 4, the dielectric 5 and the like are assembled and manufactured, there is a problem that the number of parts is large and the manufacturing and assembling work is complicated.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a high-frequency filter which is small in size, has a small number of parts, and is easy to manufacture.

[Means for solving problems]

The high frequency filter according to the present invention comprises an outer conductor formed of a conductive film adhered to the surface of a dielectric block, and an inner conductor adhered to the inner peripheral surface of through holes formed at predetermined intervals in the dielectric block,
It is formed of a conductor film that is seamlessly connected to the outer conductor at one end, and a spiral conductor is inserted into the inner conductor and supported by a tubular dielectric, and one end of the spiral conductor is opened to the inner conductor. It is connected to the outer conductor at the end side.

[Action]

The high-frequency wave filter according to the present invention uses a dielectric block having a large relative permittivity to shorten the wavelength, and a capacitive load is provided by a spiral conductor wire inserted into an inner conductor and supported by a cylindrical dielectric body. In addition to shortening the axial length of the inner conductor, the outer conductor and the inner conductor are formed of a conductive film that is in close contact with the dielectric block to achieve miniaturization, reduce the number of parts, and facilitate manufacturing and assembly.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
FIG. 1 shows a schematic structure of a high frequency filter according to an embodiment of the present invention. FIG. 1A is a perspective view and FIG. 1B is a sectional view taken along the line AA. In the figure, 1 is an outer conductor, 3 is an inner conductor, 5 is a dielectric block, 6a and 6b are input / output inner conductors,
Reference numeral 7 is a through hole, 8 is a spiral conductive wire, 9 is a cylindrical dielectric, and 10 is a dielectric rod.

The outer conductor 1 is formed of a conductor film which is arranged in close contact with the surface of the dielectric block 5, and the inner conductor 3 is formed with a plurality of through holes provided on one side surface of the dielectric block 5 at predetermined intervals. It is formed of a conductor film closely attached to the inner peripheral surface of 7, and has one end seamlessly connected to the outer conductor 1 to form a short-circuited end and the other end to an open end. A spiral conductor 8 wound around a dielectric rod 10 is inserted into each inner conductor 3 from its open end side, and is supported by a cylindrical dielectric 9. The spiral conductor 8 is connected to the outer conductor 1 at the end portion which is led out from the open end side of the inner conductor 3.

The input / output inner conductors 6a, 6b are formed of a conductor film and are insulated from the outer conductor, are connected to the inner conductors 3 at both ends, respectively, and divide a part of the current flowing through the inner conductor 3 into the input / output. It forms a coupling circuit.

Next, the operation will be described. The equivalent circuit of the resonator shown in the sectional view of FIG. 1 (b) is as shown in FIG. Second
In the figure, the outer conductor 1, the outer peripheral surface of the inner conductor 3, the spiral conductor 8, the inner peripheral surface of the inner conductor 3, the line 11, the line 12, respectively.
It is represented by lines 13 and 14.

The spiral conductor 8 viewed from the open end of the inner conductor 3 is a stub with an open tip, and the input admittance Y _i is expressed by the following equation.

Y _i = j Y ₀₂ tan θ (1) where Y ₀₂ is the characteristic admittance of the spiral conductor,
θ is an electrical length.

The input admittance Y _i becomes a capacitive susceptance when the electrical length θ is π / 2 or less, and becomes larger as θ approaches π / 2. Therefore, when a spiral conductor is used, a long line can be realized in a short section, so that θ can be increased and a large capacitance can be obtained in the capacitance, so that the resonance condition is satisfied. The axial length of the inner conductor 3 can be shortened.

In the high-frequency wave filter of FIG. 1 (a), the axial length of the inner conductor 3 is shorter than 1/4 wavelength as described above, so that they are mutually coupled mainly by the magnetic field.

Now, assuming that all the inner conductors resonate at the same frequency f ₀ by adjusting the insertion length of the spiral conductor wire 8,
At the frequency f ₀ , the inner conductors 3 in the resonance state are strongly coupled to each other and also strongly coupled to the input / output inner conductors 6a and 6b, so that the incident wave to the input / output terminal connected to the input / output inner conductor 6a is It is led to an input / output terminal connected to the conductor 6b. But,
At frequencies other than the frequency f ₀ , the inner conductors 3 are very weakly coupled to each other and the input / output inner conductors 6a and 6b.
Almost all the power of the incident wave to the input / output terminals connected to a and 6b is reflected. Thus, the high frequency filter of this embodiment has a function as a band pass filter.

In addition, in the said Example, although the case where the number of inner conductors was three was described, it is applicable also when the number of inner conductors is two, and when it is four or more. Further, the case where a part of the current flowing through the inner conductor is used as the input / output coupling circuit has been described, but coupling by a magnetic field or electrostatic capacitance may be used, and an effect equivalent to that of the above-described embodiment is obtained.

[Effect of device]

As described above, according to the present invention, the outer conductor and the inner conductor are formed by the conductor film adhered to the surface of the dielectric block or the inner peripheral surface of the through hole, and the inner conductor is supported by the cylindrical dielectric. Since the conductor is inserted and one end of the conductor is connected to the outer conductor at the open end side of the inner conductor, the outer conductor and inner conductor are extremely thin, and the dielectric block with a large relative dielectric constant While the spiral lead wire realizes a large capacitive load and the axial length of the inner conductor is shortened, the size can be greatly reduced, and the spiral lead wire is provided inside the inner conductor. Since it is supported by a dielectric and no external support mechanism is required, and the outer and inner conductors are conductor films that are in close contact with the dielectric block, the number of parts is small and a high-frequency filter that is easy to manufacture and assemble can be obtained. It is effective.

[Brief description of drawings]

FIG. 1 (a) is a perspective view showing a schematic configuration of a high frequency filter according to an embodiment of the present invention, and FIG. 1 (b) is FIG. 1 (a).
2 is a sectional view taken along the line AA of FIG. 2, FIG. 2 is an equivalent circuit diagram for explaining the operation, and FIG. 3 (a) is a partially cutaway plan view showing a schematic configuration of a conventional high-frequency filter. FIG. 3B is a vertical sectional front view of FIG. 1 is an outer conductor, 3 is an inner conductor, 5 is a dielectric block, 7 is a through hole, 8 is a spiral conductor, 9 is a cylindrical dielectric, and 10 is a dielectric rod. In the drawings, the same reference numerals indicate the same or corresponding parts.

Front page continuation (72) Creator Fumio Takeda 5-1-1, Ofuna, Kamakura-shi, Kanagawa Mitsubishi Electric Corporation Information & Electronics Laboratory (56) Reference JP-A-60-254802 (JP, A) -11802 (JP, U) Actually open Sho 61-50302 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A dielectric block having a plurality of through holes penetrating from one side surface to a back surface thereof at a predetermined interval, and a conductor film closely attached to an inner peripheral surface of each of the through holes. An inner conductor, and an outer conductor formed by a conductor film closely attached to the surface of the dielectric block, one end of each inner conductor being seamlessly connected, and inserted into the inner conductor. A high-frequency filter provided with a spiral conductor wire which is supported by a cylindrical dielectric and whose end portion led out from the open end of the inner conductor is connected to the outer conductor.