JP2001053512A - High-frequency resonator of temperature compensating type and high-frequency filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize temperature compensation, extending the required range with lightweight and simple constitution by constituting at least one of an inner conductor and an outer conductor with a member obtained by plating plastic whose coefficient of linear expansion can be selected to be a proper value. SOLUTION: Aluminum, whose specific gravity is small is used for the material of an outer conductor 2, a brass component, is used for an adjusting screw 3 for adjusting a resonance frequency, and phlyphenylene sulfide is used for the structure member of an inner conductor 1. Concerning polyhenylene sulfide, a coefficient of linear expansion can be selected arbitrarily, extending a wide range by adjusting the blending ratio of material pellet and it has characteristic capable of reducing a specific gravity as compared with metals. By using aluminum for the outer conductor 2 and brass for the adjusting screw and selecting the line coefficient of linear expansion of the inner conductor 1 to be a desired value, variation of the resonance frequency due to temperature variation can be compensated with sufficient accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency resonator and a high-frequency filter using the same, and more particularly to a temperature-compensated high-frequency resonator and a high-frequency filter for automatically compensating for a change in resonance frequency due to a temperature change.

[0002]

2. Description of the Related Art FIG. 1 is a conceptual diagram showing a basic structure of a high-frequency coaxial resonator. A cylindrical outer conductor 2 is disposed coaxially inside the outer conductor 2 and in contact with the bottom surface of the outer conductor 2. The inner conductor 1 is provided so as to be engaged with a screw hole provided at, for example, the upper center of the upper surface of the outer conductor 2 so as to face the upper surface of the inner conductor 1 via a minute gap. 1 is provided with an adjusting screw 3 which constitutes a trimmer capacitor. FIG.
(A) shows the cross section of this high-frequency resonator, D1, D2
Indicates the outer diameter of the inner conductor 1 and the inner diameter of the outer conductor 2, respectively, and the adjusting screw 3 projects below the upper surface of the inner conductor 2 by H3,
A minute gap of H2 is formed between the upper surface of the inner conductor 1 having a length of H1. FIG. 1B is a perspective view showing the positional relationship among the inner conductor 1, the outer conductor 2, and the adjusting screw 3, in which the outer conductor 2 is represented as if it were transparent.

Such a high-frequency resonator is used, for example, in a BPF (Band Filter) for a data link device shown in FIG. FIG. 2A is an external view of a BPF including four high-frequency coaxial resonators shown in FIG. 1, and FIG. 2B shows an internal structure of the BPF with an upper lid removed, and two adjacent high-frequency coaxial resonators. Are connected by a notch window provided in a part of the outer conductor that is in contact.

The resonance frequency of the high-frequency coaxial resonator shown in FIG.
= 2300 MHz and characteristic impedance Z = 75Ω. One example of each dimension is as follows. The length H1 of the inner conductor 1 is, for example, 1/8 of the wavelength λ = c / f (c: speed of light), and H1 = λ / 8 ≒ 16.29307883 mm Also, assuming that the outer diameter of the inner conductor 1 is D1 = 9.8 mm, for example, the inner diameter D2 of the outer conductor 2 is D2 = D1 · exp (2π · c · ε ₀ · Z · √ε _r ). ≒ 34.24896048 mm. Here, ε ₀ and ε _r are the permittivity of free space and the relative permittivity of air, respectively. At this time, assuming that the effective inductance L between the inner and outer conductors is ω = 2πf, L = Z · tan (2πH1 / λ) /ω≒5.189834E-09H, and the effective capacitance C is C = 1 / (ω ² L)） 9.22637E-13F That is, by adjusting the gap H2 between the inner conductor 1 and the adjusting screw 3 to H2 = ε ₀ ε _r π (D1 / 2) ² /CＣ0.724338953 mm, the resonance frequency f = 2300 MHz.
Is obtained.

However, when the temperature changes, the above dimensions change due to the linear expansion of the member used, and the resonance frequency also changes. For this reason, conventionally, for example, a metal piece 4 for temperature compensation using a bimetal is provided inside an outer conductor 2 as shown in FIG. 3A, or a cylindrical inner conductor 1 as shown in FIG. Is formed of two kinds of metals having different linear expansion coefficients, thereby appropriately setting the relative relationship of the linear expansion coefficient with the outer conductor 2, thereby compensating for the temperature change of the resonance frequency of the high-frequency resonator. .

[0006]

However, FIG.
The method (a) of using a metal piece for temperature compensation using a bimetal not only complicates the structure and increases the manufacturing cost, but also causes the bimetal to vibrate due to externally applied acceleration and change the resonance frequency. For example, there is a problem that it cannot be used for mobile equipment.

In the method of appropriately setting the relative relationship between the linear expansion coefficients of the inner conductor 1 and the outer conductor 2, the linear expansion coefficient of the metal cannot be arbitrarily selected in the prior art using a metal for the inner conductor.
As shown in FIG. 3B, for example, the inner conductor 1 is formed of two kinds of metals having different linear expansion coefficients, and it is necessary to effectively adjust the linear expansion coefficient by means such as appropriately setting the composition ratio. In addition to complicating the structure, in order to obtain the required effective linear expansion coefficient, it is necessary to use a metal having a small linear expansion coefficient, for example, brass, etc., which makes it difficult to reduce the weight of the product. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a high frequency resonator which has a lightweight and simple structure, has sufficient accuracy, and is temperature-compensated over a required range. It is an object to provide a high-frequency filter using the high-frequency resonator.

[0009]

In order to achieve the above object, in the temperature compensated high-frequency resonator according to the present invention, at least one of the inner conductor and the outer conductor is made of, for example, polyphenylene sulfide (hereinafter, referred to as PPS). By using a metal-plated plastic having a small specific gravity and a linear expansion coefficient that can be selected over a wide range, the ratio of the linear expansion coefficient between the inner conductor and the outer conductor can be appropriately adjusted. Was set to.

That is, the temperature-compensated high-frequency resonator according to the present invention, in a high-frequency resonator having an inner conductor and an outer conductor, can select at least one of the inner conductor and the outer conductor to have an appropriate linear expansion coefficient. It is characterized by comprising a member plated with plastic.

Further, in a high-frequency resonator having an inner conductor, an outer conductor, and an adjusting screw for adjusting an effective capacitance between the inner conductor and the outer conductor, at least one of the inner conductor, the outer conductor, and the adjusting screw is connected to a wire. It is characterized in that it is constituted by a member obtained by plating a plastic whose expansion coefficient can be selected to an appropriate value.

Further, the plastic is characterized in that it is polyphenylene sulfide.

In addition, the coefficient of linear expansion of the plastic is selected in consideration of design specifications so that the temperature change of the resonance frequency is within a required range.

Still further, a temperature-compensated high-frequency filter according to the present invention is provided with one or more combinations of the temperature-compensated high-frequency resonator having the above characteristics.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to FIG.
A high-frequency coaxial resonator having 0 MHz and a characteristic impedance of 75Ω will be described as an example.

In the first embodiment, aluminum having a small specific gravity is used for the material of the outer conductor 2, a commercially available brass component is used for the adjusting screw 3 for adjusting the resonance frequency, and PPS is used for the structural member of the inner conductor 1. Using. PPS can select the linear expansion coefficient arbitrarily over a wide range by adjusting the mixing ratio of the raw material pellets, and the specific gravity can be made lighter than metal, but other materials with similar characteristics May be used. FIG. 4 shows the linear expansion coefficients of the related members.

Referring to FIG. 1, as exemplified above, the outer diameter D1 of the inner conductor 1 is 9.8 mm at a temperature of 25 ° C. and the length H
1 at 25 ° C, 1/8 wavelength, 16.29309783m
m, the inner diameter D2 of the outer conductor 2 is set to 34.248.
96048 mm, the gap H between the inner conductor 1 and the adjusting screw 3
2 was adjusted to 0.724333853 mm at 25 ° C., so that the resonance frequency f = 2300.000 at 25 ° C.
A high-frequency coaxial resonator having a characteristic impedance of 75 Ω in MHz is obtained.

In this case, at the temperature t, the outer diameter and the length of the inner conductor 1 are D1 ', the inner diameter of the H1' outer conductor 2 is D2 ', the protrusion length of the adjusting screw is H3', and the inner conductor 1 and the adjusting screw 3 , The characteristic impedance Z ′ at the temperature t, the effective inductance L ′ between the inner and outer conductors, and the effective capacitance C ′ are Z ′ = ln (D2 ′ / D1 ′) / (2π · c · ε ₀・ √
the _{ε r) L '= Z'} · tan (2πH1 '/ λ) / ω C' = ε 0 · ε r · π · (D1 '/ 2) 2 / H2'. Therefore, aluminum is used for the outer conductor 2 and brass is used for the adjusting screw 3, and the projecting length H3 of the adjusting screw at 25 ° C. =
When it is 0.5 mm, the linear expansion coefficient of the inner conductor 2 is 0.00
With the selection of 00209, a change in resonance frequency due to a temperature change can be compensated with sufficient accuracy as described below.

That is, for example, at t = 100 ° C., the dimensions are D1 ′ = D1 (1 + 0.0000209 × 75) D2 ′ = D2 (1 + 0.0000231 × 75) H1 ′ = H1 (1 + 0.0000209 × 75) H2 '= (H1 + H2 + H3) (1 + 0.000023)
1 × 75) −H1′−H3 ′ H3 ′ = H3 (1 + 0.0000175 × 75). By substituting these into the above equation, the resonance frequency f ′ at 100 ° C. is calculated as f ′ = 1 / (2π √ (L ′ · C ′)) = 2300.000 MHz.

In this embodiment, as the inner conductor 1, a PPS pellet mixed so as to have a linear expansion coefficient of 0.0000209 is heated and melted, and then subjected to injection molding using a mold and plating treatment. . Further, in the plating process, after performing electroless copper plating of 3 to 5 μm,
μm silver plating was performed.

In the above embodiment, the inner conductor 1 is made of plated PPS. However, the outer conductor 2 is replaced with plated PPS by using, for example, PPS having the same linear expansion coefficient as aluminum of 0.0000231. Can also be planned. Further, the inner conductor 1 may be made of PPS, for example, by using aluminum and plating the outer conductor 2. In this case, assuming that other conditions are the same as those of the above-described embodiment, by selecting the linear expansion coefficient of PPS to 0.0000255, it is possible to obtain a high-frequency coaxial resonator which is temperature-compensated similarly to the above-described embodiment. Furthermore, for example, aluminum is used for the inner conductor 1 and the outer conductor 2 and the adjusting screw 3 is used.
May be composed of PPS plated. in this case,
By setting the protrusion length H3 of the adjusting screw at 25 ° C. = 3.0 mm and setting the linear expansion coefficient of the PPS to 0.00000871 with the other conditions being the same as in the above-described embodiment, the temperature compensation is performed in the same manner as in the above-described embodiment. The obtained high-frequency coaxial resonator can be obtained.

The embodiment of the present invention has been described above by taking the high-frequency resonator having the basic coaxial structure shown in FIG. 1 as an example. However, the scope of the present invention is limited to this basic coaxial resonator. Instead, the present invention can be effectively applied to a general high-frequency resonator having an inner conductor and an outer conductor and whose resonance frequency depends on the dimensional relationship between the inner conductor and the outer conductor.

[0023]

As described above, according to the present invention, in a high-frequency resonator having an inner conductor and an outer conductor, adjustment for adjusting the effective capacitance between the inner conductor and the outer conductor, and between the inner conductor and the outer conductor. At least one of the screws is made of a plastic plated with metal whose coefficient of linear expansion can be selected arbitrarily over a wide range.
It is possible to provide a high-frequency resonator and a high-frequency filter that are stable, lightweight, and temperature-compensated with sufficient accuracy, and are suitable for use in, for example, aircraft-mounted equipment.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a basic structure of a high-frequency coaxial resonator.

FIG. 2 is a perspective view illustrating a configuration example of a high-frequency filter.

FIG. 3 is a conceptual diagram showing a conventional technique relating to temperature compensation of a high-frequency resonator.

FIG. 4 is a table illustrating a linear expansion coefficient and a specific gravity of a material.

[Explanation of symbols]

 Reference Signs List 1 inner conductor 2 outer conductor 3 adjusting screw 4 metal piece for temperature compensation

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5J006 HA02 HA14 HA17 HA33 JA01 LA16 MA01 MB01 MB02 NB06 PA10 5J013 DA06

Claims (5)

[Claims] 1. A high-frequency resonator having an inner conductor and an outer conductor, wherein at least one of the inner conductor and the outer conductor is made of a member plated with plastic whose linear expansion coefficient can be selected to an appropriate value. A temperature-compensated high-frequency resonator characterized in that: 2. A high-frequency resonator comprising an inner conductor, an outer conductor, and an adjusting screw for adjusting an effective capacitance between the inner conductor and the outer conductor, wherein at least one of the inner conductor, the outer conductor, and the adjusting screw is connected to a wire. A temperature-compensated high-frequency resonator comprising a member plated with plastic whose expansion coefficient can be selected to an appropriate value. 3. The temperature compensated high-frequency resonator according to claim 1, wherein the plastic is polyphenylene sulfide. 4. The plastic expansion coefficient according to claim 1, wherein the linear expansion coefficient of the plastic is selected so that the temperature change of the resonance frequency is within a required range in consideration of design specifications. Temperature compensated high frequency resonator. 5. A temperature-compensated high-frequency filter comprising one or more combinations of the temperature-compensated high-frequency resonator according to claim 1.