JP2009267702A - High-frequency component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-frequency component which restrains the variations in the resonance frequency due to temperature. <P>SOLUTION: The high-frequency component has a cylindrical cavity 10, a belt-like member 20, and metal posts 21, 22. The belt-like member 20 is arranged along the periphery of the cylindrical cavity 10. The metal posts 21, 22 penetrate the belt-like member 20 and are inserted to the cylindrical cavity 10. The linear expansion coefficient for forming the belt-like member is smaller than the linear expansion coefficient of a material that forms the cylindrical cavity 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-frequency component used in a high-frequency wireless communication apparatus operating in a microwave band or a millimeter wave band.

The operation principle of a conventional typical circular waveguide type TE111 mode resonator used in a high frequency band above the microwave band will be described with reference to FIG.
This type of TE111 mode resonator includes a metal cylindrical cavity 10 whose ends are closed by end plates, and an input waveguide 11 and an output waveguide 12 that are rectangular waveguides each having a fundamental mode of TE10. And. The end plates at both ends of the cylindrical cavity 10 have coupling holes 13 for converting the TE10 mode of the input waveguide 11 into the TE11 mode of the circular waveguide, and the TE11 mode of the circular waveguide is used as the output waveguide. A coupling hole 14 for converting the tube 11 to the TE10 mode is formed. The coupling holes 13 and 14 are coupled to the main electric field 15 of the circular waveguide TE11 mode at a coupling degree K. FIG. 10 shows an example in which the resonance order is “1”, and the main electric field 15 is in a single direction.

The TE10 mode electromagnetic wave guided to the input waveguide 11 is converted into the TE11 mode with the coupling degree K through the coupling hole 13 and guided to the cylindrical cavity 10. The TE10-mode electromagnetic wave in the cylindrical cavity 10 is guided to the output-side coupling hole 14 with a coupling degree K. The position of the coupling hole 14 is a position where the axial length of the resonator becomes a half wavelength of a desired resonance frequency. As a result, the resonator operates as a TE111 mode resonator as a whole.
An equivalent circuit diagram of the resonator when operating in the TE111 mode is shown in FIG. In the figure, K indicates the degree of coupling of the coupling holes 13 and 14, respectively. As shown in FIG. 11, the cylindrical cavity 10 becomes an LC resonance circuit. FIG. 12 shows the electromagnetic field distribution of the TE11 mode of the circular waveguide. The solid line indicates the electric field distribution, and the broken line indicates the magnetic field distribution.

  The cylindrical cavity 10 may be provided with a metal post or the like whose tip is inserted into the cylindrical cavity 10 for the purpose of varying the resonance frequency. FIG. 13 is a diagram partially showing the cylindrical cavity 10 of the TE111 mode resonator shown in FIG. 10 for convenience. In the example shown in the figure, the metal posts 21 and 22 are inserted in a substantially central portion of the cylindrical cavity 10 so that their tips can move in the same direction as the direction of the main electric field 15. FIG. 14 is a cross-sectional view of the cylindrical cavity 10 in which the metal posts 21 and 22 are arranged as shown in FIG. As shown in the figure, the metal posts 21 and 22 are movably inserted in the same direction as the direction of the main electric field 15 of the TE111 mode, so that the portion C of the LC resonance circuit, that is, the capacitive reactance changes, The resonance frequency varies. In general, as the amount of insertion increases, the capacitive reactance increases and the resonance frequency decreases. This is the operation principle of a general TE111 mode resonator.

It should be noted that arranging the metal posts 21 and 22 in the substantially central portion of the cylindrical cavity 10 is only one method for increasing the change in the capacitive reactance. The arrangement positions of the metal posts 21 and 22 may be determined according to a desired change amount.
FIG. 15 shows the electric field distribution when the resonance order in the resonator shown in FIG. 10 is “2”. As can be seen from FIG. 15, when the resonance order is “2”, the direction of the main magnetic field 16 becomes two directions. Although the resonance order may be “3” or more, the resonance order may be determined in accordance with the desired required performance, so the case of “3” or more is omitted here.

There are various modifications of the TE111 mode resonator.
FIG. 16 is a diagram showing a circular waveguide type double TE111 mode resonator as one of modifications. For convenience, the same components as those of the resonator shown in FIG. The difference from FIG. 10 is that two orthogonal electric fields in the resonator are coupled to form a so-called double TE11 mode.
The “double TE11 mode” refers to a mode in which a horizontal polarization TE11 mode and a vertical polarization TE11 mode in a circular waveguide are orthogonal to each other, and two single TE11 modes are cascaded. Equivalent to connecting.

  FIG. 17 shows only the cylindrical cavity 10 of the resonator shown in FIG. In the cylindrical cavity 10, metal posts 23 and 24 are disposed substantially at the center in order to make the resonance frequency variable. The metal post 23 is inserted such that its tip is movable in the same direction as the direction of the main electric field 151 of vertical polarization. The metal post 24 is inserted such that its tip is movable in the same direction as the direction of the main electric field 152 of horizontal polarization. FIG. 18 is a cross-sectional view of the vicinity of the center of the cylindrical cavity 10. Since the metal posts 23 and 24 are inserted in the same direction with respect to the vertical / horizontal main electric fields 151 and 152 of the resonance mode TE111, the capacitive reactance of the resonator increases and the resonance frequency varies. The reason why the metal posts 23 and 24 are arranged near the center of the resonator is to increase the change in the capacitive reactance, and the arrangement position is determined according to a desired change amount.

  FIG. 19 is a diagram showing a waveguide bandpass filter configured by cascading conventional circular waveguide type double TE111 mode resonators. FIG. 20 is an equivalent circuit diagram of this band-pass filter. K 1 is the degree of coupling between the coupling holes 13 and 14, K 2 is the degree of coupling between the two orthogonal electric fields 151 and 152, and K 3 is the degree of coupling of the coupling hole 16 in the cylindrical cavity 10.

The problem in the conventional technology as described above is the fluctuation of the resonance frequency accompanying the temperature change. Normally, a circular waveguide resonator is manufactured by processing metal, but there are mainly two reasons why the resonance frequency fluctuates due to a temperature change when the humidity is kept constant.
The first reason is that the diameter of the circular waveguide, which depends on the linear expansion coefficient of the resonator material, varies due to temperature change.
The second reason is that the axial length of the cylindrical resonator depends on the linear expansion coefficient of the resonator material due to temperature change.

The resonance frequency f0 of the circular waveguide TE11n mode resonator is expressed by the following equation (1).
f0 = c√ ((X / π) ² + (nD / 2L) ² ) / D (1)
D: Diameter of circular waveguide, L: Resonance axis length, n: Resonance order, “1” in TE111 mode, X: 1.841 in TE11 mode

The physical dimensions in consideration of the temperature change of the circular waveguide type resonator are expressed by equations (2) and (3) depending on the linear expansion coefficient α of the members constituting the resonator.
D = D + α · Δt · D (2)
L = L + α · Δt · L (3)

  The diameter D and height L of the resonator expand and increase as the temperature increases. For example, in a resonator of 7 [GHz] band, the resonance frequency fluctuates as indicated by a solid line and a broken line in FIG. 21 when the linear expansion coefficient of the resonator member is α1 or α2 (α1> α2) due to temperature change.

  As is clear from FIG. 21, the temperature dependence of the resonance frequency has a negative slope, and the fluctuation rate depends on the linear expansion coefficient of the resonator. Conventionally, even when a circular waveguide type TE11n mode resonator is used alone or when a bandpass filter is used, the temperature fluctuation of the resonance frequency is not preferable. In order to suppress the temperature fluctuation, A material having a very small linear expansion coefficient is selected as the material of the resonator.

For example, the resonance frequency of a resonator formed of iron with a linear expansion coefficient of 12 × 10 ⁻⁶ / K is a temperature fluctuation rate corresponding to this linear expansion coefficient, but an imper that is an alloy of iron and nickel is used. In this case, the temperature fluctuation rate is improved to 1/10.
However, the necessity of adopting a metal material having an extremely small linear expansion coefficient in order to suppress fluctuations due to temperature changes in the resonance frequency leads to high costs, and such a metal material is difficult to obtain. .

Patent Document 1 discloses a technique for canceling the fluctuation of the resonance frequency due to expansion and contraction of the TE10 resonator by providing a drive mechanism in the resonator and changing the insertion amount of the frequency adjusting screw.
JP-A-9-275304

  The main object of the present invention is to provide a high-frequency component that suppresses fluctuation of the resonance frequency due to temperature without using an expensive and poorly available metal material.

The high-frequency component of the present invention that solves the above problems has a waveguide formed in a cylindrical shape, and linearly expands along the outer periphery of the waveguide more than the material forming the waveguide. A belt-like member made of a material having a small coefficient is attached.
The high-frequency component having such a configuration is provided with a belt-like member, thereby suppressing a change in dimensions due to a temperature change in the radial direction of the waveguide. Therefore, the fluctuation of the resonance frequency accompanying the temperature change of the waveguide size as shown in the equation (1) is suppressed.

For example, when the band-shaped member is attached to a portion where the electric field generated in the waveguide is the largest, the effect of suppressing the fluctuation due to the temperature change of the resonance frequency becomes high.
Note that such a high-frequency component may be provided with a metal post that penetrates through the band-shaped member and is at least partially inserted into the waveguide. In this case, the post can move in the same direction as the direction of the electric field generated in the waveguide, and the resonance frequency is determined by the amount inserted into the waveguide.

  The high-frequency component according to the present invention includes a waveguide formed in a cylindrical shape, and at least a part of the waveguide is inserted into the waveguide from the outer periphery of the waveguide, and linear expansion is greater than the material forming the waveguide. And an adjustment post formed of a material having a small coefficient. The post is movable in the same direction as the direction of the electric field generated in the waveguide, and the resonance frequency is determined by the amount inserted into the waveguide.

The adjustment post generates a capacitive reactance when a high-frequency component is used as a resonator. Since the adjustment post is movable, that is, the amount of insertion into the waveguide is variable, the resonance frequency is variable. The variation of the dimension with respect to the temperature change of the adjusting post is smaller than that of the waveguide because of the linear expansion coefficient. For this reason, it is possible to suppress fluctuations associated with temperature changes in the resonance frequency. The material of the adjustment post need not be limited to metal, and ceramic or the like that can easily obtain a low linear expansion coefficient can also be used.
For example, the adjustment post is attached to a portion where the electric field generated in the waveguide is the largest, so that the effect of suppressing the fluctuation due to the temperature change of the resonance frequency becomes high.

  According to the present invention as described above, it is possible to provide an inexpensive high-frequency component that reduces the amount of use of an expensive and poorly available metal material and suppresses fluctuations in the resonance frequency due to temperature.

[First Embodiment]
FIG. 1 is a diagram showing a circular waveguide TE111 mode resonator according to a first embodiment of the present invention.
The difference from the conventional resonator shown in FIG. 10 is that a belt-like member 20 is provided along the outer periphery of the cylindrical cavity 10 with a material having a lower linear expansion coefficient than the material used for the cylindrical cavity 10. The band-like member 20 is joined to the cylindrical cavity 10 by, for example, brazing. In FIG. 1, metal posts 10 and 11 as shown in FIG. 13 are inserted into the cylindrical cavity 10 through the belt-like member 20 in order to adjust the resonance frequency. In the first embodiment, the material of the cylindrical cavity 10 is iron having a linear expansion coefficient of 12 × 10 ⁻⁶ / K, and the material of the belt-shaped member 20 is Invar having a linear expansion coefficient of 1.2 × 10 ⁻⁶ / K.

  When the cylindrical cavity 10 and the belt-like member 20 are made of the same material, the linear expansion coefficient is the same, so the variation rate of the resonance frequency with respect to the temperature change is not different from the conventional one. However, if the linear expansion coefficient of the belt-like member 20 is made lower than the linear expansion coefficient of the cylindrical cavity 10, the change in shape due to the temperature of the belt-like member 20 is smaller than the change in shape due to the temperature of the cylindrical cavity 10, so Even if the cylindrical cavity 10 tries to deform in the diametrical direction, the belt-like member 20 prevents it. For this reason, the fluctuation of the resonance frequency due to the temperature change of the cylindrical cavity 10 is suppressed. In particular, in FIG. 1, since the band-shaped member 20 is provided at the center of the cylindrical cavity 20, the change in the resonance frequency due to the temperature change of the TE 111 mode resonator having the largest electric field at the center of the cylindrical cavity 20 is suppressed. Great effect.

  In this embodiment, the belt-like member 20 has a ring shape that completely surrounds the cylindrical cavity 10. However, it goes without saying that the same effect can be obtained even if the shape is not a ring shape but a part of the ring shape. Nor. Moreover, although invar is used for the strip-shaped member 20, the cost can be suppressed to a much lower cost than when the whole is configured with invar.

[Second Embodiment]
FIG. 2 is a diagram showing a circular waveguide type TE112 mode resonator according to the second embodiment. The difference from the resonator according to the first embodiment is that since the resonance order is “2”, two portions where the electric field is the largest are generated inside the resonator. , 202 are arranged. The strip members 201 and 202 are also provided with metal posts 21A, B, 22A and B for adjusting the resonance frequency.
The resonator according to the second embodiment is different from the resonator according to the first embodiment as described above. However, the suppression of the variation of the resonance frequency with respect to the temperature change by the strip members 201 and 202 is described in the first embodiment. Is the same.

[Third Embodiment]
FIG. 3 is a diagram showing a circular waveguide type double TE111 mode resonator according to a third embodiment. The difference from the first embodiment is that the metal posts 23 and 24 for adjusting the resonance frequency of the double TE11 mode are installed corresponding to the main electric fields 151 and 152 of vertical polarization and horizontal polarization. Is a point. The metal post 23 is inserted so as to be movable in the same direction as the direction of the main electric field 151 of vertical polarization. The metal post 24 is inserted so as to be movable in the same direction as the direction of the horizontally polarized main electric field 152.
The resonator according to the third embodiment is different from the resonator according to the first embodiment as described above. However, the suppression of the resonance frequency with respect to the temperature change by the strip member 20 is the same as that in the first embodiment. .

[Fourth Embodiment]
FIG. 4 is a diagram showing a circular waveguide type double TE112 mode resonator according to a fourth embodiment. The difference from the second embodiment is that the metal posts 23A, B, 24A, B for adjusting the resonance frequency of the double TE11 mode correspond to the main electric fields 151, 152 of vertical polarization and horizontal polarization, It is a point that is installed. The metal posts 23A and B correspond to the vertically polarized main electric field 151, and the metal posts 24A and B correspond to the horizontally polarized main electric field 152.
The suppression of the resonance frequency with respect to the temperature change by the band members 201 and 202 of the resonator of the fourth embodiment is the same as that of the first embodiment.

In each of the above embodiments, a belt-like member having a small linear expansion coefficient is wound around a portion where the electric field of the TE11 resonator is concentrated, thereby suppressing the expansion of the resonator body and suppressing the fluctuation of the resonance frequency. Further, the dual mode of the TE11 resonator is effective for both the first mode resonance frequency fluctuation and the second mode resonance frequency fluctuation.
The expansion of the metal post is the same as in the past, and as in Patent Document 1, when the metal post (screw) moves in the direction in which the resonator is removed at the time of resonator expansion, there is a possibility that the variation in the resonator frequency is large. However, by winding the belt-shaped member around the resonator, an effect can be obtained with a simpler structure than the case where the drive mechanism of Patent Document 1 is provided.

[Fifth Embodiment]
FIG. 5 is a diagram showing a circular waveguide TE111 mode resonator according to a fifth embodiment. The difference from the conventional resonator shown in FIG. 13 is that a material having a smaller linear expansion coefficient than the material used for the cylindrical cavity 10 is used as the material for the adjustment posts 27 and 28 for adjusting the resonance frequency. . In this embodiment, ceramics having a linear expansion coefficient of about 2.0 × 10 ⁻⁶ / K are used as the material of the adjustment posts 27 and 28, and the linear expansion coefficient of the material of the cylindrical cavity 10 is 12 × 10 6. ^-6 / K iron is used.

The principle that the electric field inside the cylindrical cavity 10 acts on the adjustment posts 27 and 28 will be described with reference to FIG.
In the adjustment posts 27 and 28, at least a portion inserted into the resonator is ceramic. The electric field in the resonator is concentrated on the adjustment posts 27 and 28, and the capacitive reactance is increased as an equivalent circuit. When operating as a resonator, the resonance frequency is determined including this capacitive reactance.

If the same iron as the resonator is used as the material of the adjustment posts 27 and 28 as in the conventional case, when the temperature rises, the adjustment posts 27 and 28 are inserted with a linear expansion coefficient of 12 × 10 ⁻⁶ / K. Increase the length and diameter, and change the resonance frequency to the low frequency side. On the other hand, the cylindrical cavity 10 similarly increases the diameter and cylindrical axial length of the cylindrical cavity 10 with a linear expansion coefficient of 12 × 10 ⁻⁶ / K, and changes the resonance frequency to the low frequency side. As described above, the actions of the cylindrical cavity 10 and the adjustment posts 27 and 28 on the resonance frequency are all changed to the low frequency side. For this reason, if brass (18 × 10 ⁻⁶ / K) having a large linear expansion coefficient is used as the material of the adjustment posts 21 and 22, the temperature fluctuation of the resonance frequency is further increased.

When the linear expansion coefficient of the adjustment posts 27 and 28 is smaller than that of the cylindrical cavity 10, the insertion length and the post diameter of the adjustment posts 27 and 28 change according to the linear expansion coefficient when the temperature changes. However, since the amount of change is small, the resonance frequency is governed by temperature fluctuations caused by the cylindrical cavity 10. In this embodiment, ceramics having a linear expansion coefficient of about 2.0 × 10 ⁻⁶ / K was used as a material for the adjustment posts 27 and 28. However, if there is no problem in availability, linear expansion like Invar is used. A metal having a small coefficient (1.2 × 10 ⁻⁶ / K) may be used.

  In this embodiment, since the resonance order of the resonator is “1”, the adjustment posts 27 and 28 are provided substantially at the center of the cylindrical cavity 10. When the resonance order is “2”, as in the band-shaped members 201 and 202 of the second embodiment, two portions where the electric field is greatest are generated inside the resonator. A post is placed.

[Sixth Embodiment]
FIG. 7 is a diagram showing a circular waveguide type double TE111 mode resonator according to a sixth embodiment. About suppression of the resonance frequency with respect to a temperature change, since it is the same as 5th Embodiment, description is abbreviate | omitted.
FIG. 8 and FIG. 9 show the relationship between the adjustment posts 27 to 30 inside the resonator and the main electric fields 151 and 152 in the double TE11 mode. Adjustment posts 27 to 30 are installed corresponding to main electric fields 151 and 152 of vertical polarization and horizontal polarization. The adjustment posts 27 and 29 are inserted so as to be movable in the same direction as the direction of the main field 151 of vertical polarization. The adjustment posts 28 and 30 are inserted so as to be movable in the same direction as the direction of the main electric field 152 of horizontal polarization. For this reason, the capacitive reactance of the resonator increases and the resonance frequency varies.

It is a figure which shows the circular waveguide type resonator which concerns on 1st Embodiment of this invention. It is a figure which shows the circular waveguide type resonator which concerns on 2nd Embodiment of this invention. It is a figure which shows the circular waveguide type resonator which concerns on 3rd Embodiment of this invention. It is a figure which shows the circular waveguide type resonator which concerns on 4th Embodiment of this invention. It is a figure which shows the circular waveguide type resonator which concerns on 5th Embodiment of this invention. It is a figure for demonstrating the principle in which the electric field inside a cylindrical cavity acts on the adjustment post. It is a figure which shows the circular waveguide type resonator which concerns on 6th Embodiment of this invention. It is a figure which shows the relationship between the adjustment post inside a resonator, and a main electric field. It is a figure which shows the relationship between the adjustment post inside a resonator, and a main electric field. It is a figure which shows the conventional circular waveguide type resonator. It is an equivalent circuit schematic of the resonator of FIG. It is a figure which shows the electromagnetic field distribution of TE11 mode of a circular waveguide. It is the figure which showed only the cylindrical cavity of the resonator shown in FIG. It is sectional drawing of the cylindrical cavity by which the metal post is arrange | positioned. It is a figure which shows the electric field distribution of the resonator whose resonance order is "2". It is a figure which shows the resonator of the conventional circular waveguide type double TE111 mode. It is a figure which shows only the cylindrical cavity of the resonator shown in FIG. It is sectional drawing of the cylindrical cavity by which the metal post is arrange | positioned. It is a figure which shows the waveguide bandpass filter comprised by connecting the conventional circular waveguide type double TE111 mode resonator in cascade. FIG. 20 is an equivalent circuit diagram of the bandpass filter of FIG. 19. It is a figure which shows the fluctuation | variation of the resonant frequency by a temperature change.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Cylindrical cavity 11 Input waveguide 12 Output waveguide 13, 14, 16 Coupling hole 15, 151, 152 Main electric field 20, 201, 202 Band-shaped member 21-26, 21A, B, 22A, B, 23A, B, 24A, B Metal post 27-30 Post for adjustment

Claims (5)

Having a cylindrically shaped waveguide,
A strip-shaped member formed of a material having a smaller linear expansion coefficient than the material forming the waveguide is attached along the outer periphery of the waveguide.
High frequency components. The strip member is attached to a portion where the electric field generated in the waveguide is the largest.
The high frequency component according to claim 1. A metal post penetrating at least a part of the waveguide through the strip member is provided;
The post is movable in the same direction as the direction of the electric field generated in the waveguide, and the resonance frequency is determined by the amount inserted into the waveguide.
The high frequency component according to claim 1. A waveguide formed into a cylindrical shape;
An adjustment post formed of a material having at least a part inserted into the waveguide from the outer periphery of the waveguide and having a smaller linear expansion coefficient than the material forming the waveguide;
The post is movable in the same direction as the direction of the electric field generated in the waveguide, and the resonance frequency is determined by the amount inserted into the waveguide.
High frequency components. The adjustment post is attached to a portion where the electric field generated in the waveguide is the largest.
The high frequency component according to claim 4.

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