JPH0837407A - Microwave circuit element with movable short-circuit plate - Google Patents

Abstract

PURPOSE:To obtain the product with the longer service life by halving a length of a prescribed part of an H plane inner wall of a waveguide with respect to the wavelength of an operating microwave so as to make a state of shielding the microwave nearly completely stable. CONSTITUTION:A microwave leaked from a microwave leakage prevention means 11 is propagated in a kind of a square waveguide 1 making up of an E plane inner wall 1A, both H plane inner walls 1C, 1D and a movable short- circuit plate 2 in the TEmn mode. Furthermore, the microwave propagates through a space in which the short-circuit plate 2 and the E plane inner wall of the waveguide 1 are not electrically connected via a microwave leakage prevention means 22. Then the cut-off wavelength in the TE10 mode is obtained and the length of the space in the H plane inner wall direction of the waveguide is selected to be a half of the wavelength of the operating microwave to cut off microwaves in all modes leaked from the prevention means 11. Furthermore, a friction resistance of the prevention means 22 with respect to the waveguide inner wall is reduced considerably and the microwave leaked from the means 11 is completely shielded by the means 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave circuit element provided with a movable short circuit plate.

[0002]

2. Description of the Related Art In a microwave circuit, a movable short-circuit plate is used for an impedance matching circuit and a resonance circuit. For example, in a cavity resonator, a movable short-circuit plate is arranged in a rectangular waveguide, and this movable short-circuit plate short-circuits the rectangular waveguide at 1/2 of the in-tube wavelength or a positive multiple thereof, thereby providing a large internal constant. Generates a standing wave and uses it as a resonance circuit.

Further, in the EH tuner, branching devices are provided on the electric field surface and the magnetic field surface of the rectangular waveguide, and the movable short-circuit plates are arranged inside thereof. With this configuration, it is equivalent to connecting a capacitive load and an inductive load to the line, and the capacitive load and the inductive load can be adjusted by adjusting the position of the movable short-circuit plate. It can be used as a circuit.

FIG. 3 (A) is a schematic configuration diagram of a microwave circuit element having a conventional movable short-circuit plate, and FIG. 3 (B) is shown in FIG.
It is the II sectional view taken on the line of (A). As shown in the figure, a movable short-circuit plate 2 is arranged inside a rectangular rectangular waveguide 1 having a rectangular cross section, a flange 1a is provided at one end of the waveguide 1, and an end plate 3 attached to this flange is used. Closed and at the other end, a flange 1b for connecting to another rectangular waveguide
Is installed. The movable short-circuit plate 2 is connected to a rod 4 penetrating an end plate 3 that closes one end of the waveguide 1. By operating a portion of the rod 4 located outside the waveguide, the movable short-circuit plate 2 is guided. While having a proper gap G between the inner wall of the tube 1 and the inner wall of the tube 1, the waveguide 1 can be linearly moved in the tube axis direction.

In this case, since the movable electric short-circuit plate 2 and the inner walls 1A, 1B of the electric field surface of the waveguide 1 (the surface on which the electric field is generated, hereinafter referred to as the E surface) are not in a short-circuited state, microwaves are generated between them. Is also propagated and leaks, and also in terms of a surface for preventing this, the movable short-circuit plate 2 has a well-known microwave choke structure on the E-surface inner walls 1A and 1B side. 11 is provided. Further, the above-mentioned first microwave leakage prevention means may be provided also on the inner wall 1C, 1D side of the magnetic field surface of the waveguide 1 (a surface in which a magnetic field is generated, hereinafter referred to as H surface).

However, the microwave leakage prevention by the first microwave leakage prevention means 11 is not perfect, and therefore propagates through the gap G between the E-plane inner walls 1A and 1B of the waveguide 1 and the movable short-circuit plate 2. In order to shield the microwave leaking from the movable short-circuit plate 2 to the end plate 3, as the second microwave leakage prevention means 12, the E-plane inner walls 1A, 1 of the waveguide 1 are provided.
Metal contact pieces 12A and 12B for making contact with B are respectively provided along the E-plane inner walls 1A and 1B side of the movable short-circuit plate 2, and the metal contact pieces separate the E-plane inner walls 1A and 1B and the movable short-circuit plate 2 from each other. Each is electrically connected. The metal contact pieces 12A and 12B are made of a thin plate having good conductivity such as a copper alloy having a spring property, and H of the waveguide 1 of the movable short-circuit plate 2 is formed.
An elongated rectangular thin plate having approximately the same dimension as the length in the surface direction is formed into a comb shape, and the comb portion is formed into a bow shape, and the bow-shaped bulge portion is an E-plane inner wall of the waveguide facing the movable short-circuit plate 2. 1A,
The other end is attached to the movable short-circuit plate 2 so as to come into contact with 1B. Note that the electric field near the H-plane inner walls 1C, 1D side of the gap between the E-plane inner walls 1A, 1B and the movable short-circuit plate 2 is almost zero, so that the microwave propagates from this gap to the end plate 3. Almost no leakage.

[0007]

SUMMARY OF THE INVENTION The metal contact piece 12 described above.
Since it is necessary to bring A and 12B into contact with the E-plane inner walls 1A and 1B of the waveguide 1 by an appropriate spring reaction force, when a microwave circuit element having a movable short-circuit plate is used in an automatic EH tuner, Frequent linear movement of the plate 2 causes abrasion powder of the metal contact pieces 12A, 12B and the waveguide due to sliding, and, for example, when processing a semiconductor substrate,
When deposited on a portion corresponding to a microwave propagation path on the glass chamber of the plasma processing chamber, there is a problem that the plasma generated by the microwave is affected and the treatment is not performed under certain conditions. Further, since it is necessary to consider static friction and dynamic friction due to sliding, there is a problem that a drive source of the movable short-circuit plate having an excessive function must be adopted. Furthermore, the metal contact piece 12A by sliding,
There is a problem that replacement work occurs early because the wear of 12B and the waveguide 1 becomes excessive and the life becomes short.

[0008]

According to a first aspect of the present invention, a non-contact type having a microwave choke structure is provided on a movable short-circuit plate which is disposed inside the waveguide so as to be movable in the tube axis direction. In addition to the first microwave leakage prevention means, the second microwave leakage prevention means of the inner wall contact type of the waveguide for shielding the microwave leaked from the first microwave leakage prevention means is provided, and the second microwave leakage prevention means is provided. Targeting a microwave circuit element with a movable short-circuit plate, in which the movable short-circuit plate and the E-plane inner wall of the waveguide are electrically connected via a wave leakage prevention means,
The second microwave leakage prevention unit includes a rolling member and a support member that supports the rolling member, and the rolling member contacts the E-plane inner wall and the movable short-circuit plate in a state where the rolling member is in contact with at least the E-plane inner wall. It is characterized in that the length in the H-plane inner wall direction of the waveguide in the unopened portion is set to 1/2 or less of the wavelength of the microwave used.

According to a second aspect of the present invention, the rolling member comprises a roller and a bearing for rolling the roller.

Further, according to a third aspect of the present invention, the rolling member includes a ball and a ball receiver for rolling the ball.

[0011]

According to the structure described in claim 1, the microwave leaked from the first microwave leak prevention means is E
It propagates in a TE _mn mode in a kind of rectangular waveguide formed by the in-plane wall, both H-plane inner walls, and the movable short-circuit plate. Further, this microwave propagates through the second microwave leakage prevention means in a space where the movable short-circuit plate and the E-plane inner wall of the waveguide are not electrically connected. Therefore, the cutoff wavelength λc of the TE _mn mode is E, where the length between the H-plane inner walls of this waveguide is a
If the length between the in-plane walls is b, then (1 / λc) ² = (m /
2a) ² + (since it is determined from the n / 2b) ^2, TE ₁₀
By determining the mode cutoff wavelength λ c = 2a, the length of the waveguide in the H-plane inner wall direction in the above space is set to 1/2 or less of the wavelength of the microwave used, thereby preventing the first microwave leakage. All modes of microwaves leaking from the means are blocked. In addition, the frictional resistance between the second microwave leakage prevention means and the inner wall of the waveguide is significantly reduced, and
The microwave leakage prevention means stabilizes the state in which the microwave leaking from the first microwave leakage prevention means is almost completely shielded.

According to the second aspect of the invention, the microwave leaking from the first microwave leakage preventing means is shielded even if the second microwave leakage preventing means has a small number of parts. The second microwave leakage prevention means effective for reducing the space formed by the E-plane inner wall of the waveguide and the movable short-circuit plate is small.

Further, according to the structure described in claim 3,
In particular, the structure of the second microwave leakage prevention means is simplified, and the rolling movement is performed while making point contact with the inner wall of the waveguide, so that the linear movement of the movable short-circuit plate becomes smoother.

[0014]

【Example】

<Embodiment 1> FIG. 1A is a schematic constitutional view showing a first embodiment according to the present invention, and FIG. 1B is a sectional view taken along line I--I of FIG. 1A. In these figures, 1 is a waveguide, 2 is a movable short-circuit plate, 3 is an end plate, 4 is a rod, and 11 is a first microwave leakage prevention means, which is the same as in FIG. .

The second microwave leakage prevention means 22A of the present embodiment comprises a rolling member 22A 'and a supporting member 22A "for supporting the rolling member 22A'.
Is, for example, two cylindrical rollers 22 having a central axis.
A1 and 22A2 and four bearings 22A3, 22A4, 22A5 and 22A that respectively support the shaft ends of the rollers.
The support member 22A ″ includes four leaf springs 22A7, 2 having L-shapes for mounting the bearings.
It consists of 2A8, 22A9 and 22A10. Leaf spring 22A
Bearings 22A3-2 attached to one end of 7-22A10
The rollers 22A1 and 22A2 pivotally supported by 2A6 are
The leaf springs 22A are arranged so as to coincide with each other in the axial direction so that the roller contacts the E-plane inner wall 1A of the waveguide 1.
The other ends of 7 to 22A10 are attached along the E-side inner wall 1A side of the movable short-circuit plate 2.

The rollers 22A1 and 22A2 are formed to be slightly shorter than the half between the H-plane inner walls 1C and 1D of the waveguide 1, and the leaf springs 22A8 and 22A9 supporting the rollers are closely contacted with each other so that the leaf spring 22A7. , 22A8 and 22
A9 and 22A10 are the inner walls 1C and 1D of the H-plane of the waveguide 1.
The lengths of the second microwave leakage prevention means 22A in the longitudinal direction are substantially the same as the length of the movable short-circuit plate 2 in the H-plane direction. ing. If the positions of fixing the leaf springs 22A7 to 22A10 to the movable short-circuit plate 2 are properly adjusted, the rollers 22A1 and 2A2
2A2 is pressed against the E-plane inner wall 1A by a desired spring reaction force, and when the movable short-circuit plate 2 linearly moves, 2A2 makes a rolling motion while contacting the E-plane inner wall 1A.

When the second microwave leakage prevention means 22 is formed of a conductor, the E-plane inner wall 1A and the movable short-circuit plate 2 are electrically connected, so that the gap G between the E-plane inner wall 1A and the movable short-circuit plate 2 is formed. As shown in FIG. 1A, most of the microwaves propagated through the rolling member 22A 'and the supporting member 22 are
A "and a space S formed by the surface 2a of the movable short-circuit plate 2
Propagate from 1, S1 to the end plate 3 side. Further, as shown in FIG. 1B, the light propagates from the space S2 formed by the rolling member 22A 'and the E-plane inner wall 1A to the end plate 3 side.

By the way, TE _mn propagating in the rectangular waveguide
The cut-off wavelength λc of the mode is determined by
It is known that when the length between 1D is a and the length between the E-plane inner walls 1A and 1B is b, it is given by the equation (1). (1 / λc) ² = (m / 2a) ² + (n / 2b) ² (1) For example, when obtaining the cutoff wavelength λc in the TE ₁₀ mode,
Substituting m = 1 and n = 0 into the equation (1) gives λc = 2a. The cutoff wavelength λc of the TE ₂₀ mode is λc = a
Becomes That is, if the length a of the waveguide is set to be equal to or shorter than the wavelength of the microwave used, the TE ₂₀ mode is not propagated, and if it is set to be 1/2 or less of the wavelength of the microwave, T
Not only the E ₁₀ mode but also higher-order modes above the TE ₂₀ mode are not propagated.

For example, when a microwave having a frequency of 2.45 GHz (free space wavelength λ = 12.24 cm) is propagated, J
Same as IS standard number WRJ-2 a = 10.9 cm x b =
The TE ₁₀ mode is propagated using a 5.5 cm waveguide, but the waveguide length a = 10.9 cm is 12.24 cm ×
When closed to an opening length of 1/2 = 6.12 cm, TE ₁₀
It is desirable to make it smaller than 6.12 cm, as the modes will start to propagate. That is, in this example, (10.9-6.12) /10.9×100%=
It is desirable to close by 44% or more. Further, even in the case of a waveguide used for propagating higher-order modes of TE ₂₀ mode or higher, microwaves of all modes are blocked by closing up to an opening length of 6.12 cm.

Therefore, the lengths of the spaces S1 and S2 in the H-plane direction are not more than 1/2 of the length between the H-plane inner walls 1C and 1D of the waveguide 1, so that the spaces are substantially formed. The second microwave leakage prevention means 22 shields the microwaves leaking from the first microwave leakage prevention means 11 because the second microwave leakage prevention means 22 shields the microwaves.

In this embodiment, of course, the movable short-circuit plate 2
Also on the E surface inner wall 1B side of the rolling member 22
A second microwave leakage preventing means 22B composed of B'and a supporting member 22B "is provided, and the rolling member 22B 'includes rollers 22B1 and 22B2 and a bearing 22B3.
, 22B4, 22B5, 22B6, and the support member 22B ″ is a leaf spring 22B7, 22B8, 22B9, 2
It consists of 2B10. Further, although the number of rollers is two, as described above, the number of rollers may be one as long as the length is slightly shorter than the half between the H-plane inner walls 1C and 1D of the waveguide 1. Further, the length of each roller may be further shortened, and a bearing and a leaf spring may be provided at the shaft end of each roller. In this case, the state of contact with the inner wall of the E surface is improved, and H of the spaces S1 and S2
Since the length in the plane direction is further reduced, leaking microwaves can be shielded more effectively.

<Embodiment 2> FIG. 2A is a schematic configuration diagram showing a second embodiment according to the present invention, and FIG.
It is the II sectional view taken on the line of (A). In these figures,
1 is a waveguide, 2 is a movable short-circuit plate, 3 is an end plate, 4 is a rod,
Reference numeral 11 is a first microwave leakage prevention means, which is the same as that in FIG.

The second microwave leakage prevention means 32A of this embodiment is, for example, three balls 32A1, 32A2, 3
2A3 and rolling member 32A 'consisting of three ball receivers 32A4, 32A5, 32A6 for rolling the balls respectively and ball receivers 32A4 to 32A6.
3 leaf springs 32 each having an L shape for attaching
Supporting member 32A ″ consisting of A7, 32A8 and 32A9
It consists of. The ball receivers 32A4 to 32A6 attached to one ends of the leaf springs 32A7 to 32A9 are arranged in a line, and the other ends of the leaf springs 32A7 to 32A9 are brought into contact with the balls 32A1 to 32A3 to the E-plane inner wall 1A. The movable short-circuit plate 2 is attached along the E-plane inner wall 1A side.

The balls 32A1 to 32A3 and the leaf springs 32A7 to 32A9 are arranged at an interval slightly shorter than half of the distance between the H-plane inner walls 1C and 1D, and the second microwave leakage prevention means 32A. The length in the longitudinal direction is approximately the same as the length in the H-plane direction of the movable short-circuit plate 2. If the positions of fixing the leaf springs 32A7-32A9 to the movable short-circuit plate 2 are properly adjusted, the balls 32A1-3
2A3 is pressed against the E-plane inner wall 1A by a desired spring reaction force, and when the movable short-circuit plate 2 linearly moves, 2A3 makes a rolling motion while contacting the E-plane inner wall 1A.

When the second microwave leakage preventing means 32A is formed of a conductor, the E-plane inner wall 1A and the movable short-circuit plate 2 are electrically connected, so that the E-plane inner wall 1A and the movable short-circuit plate 2 are formed.
Most of the microwaves propagating through the gap G between
As shown in FIG. 1, the E-plane inner wall 1A and the rolling member 22A '
The space S3, S3 formed by the support member 22A "and the surface 2a of the movable short-circuit plate 2 propagates toward the end plate 3. However, the length of the space S3 in the H-plane direction is the same as in the first embodiment. Since the length is less than 1/2 of the length between the H-plane inner walls 1C and 1D of the waveguide 1, the above space is substantially closed by the conductor, and thus the second microwave leakage prevention. The first microwave leakage prevention means 11 by means 32
The microwave leaking from is shielded.

In this embodiment, of course, the movable short-circuit plate 2
Also on the E surface inner wall 1B side of the rolling member 32 in the same manner as above.
A second microwave leakage prevention means 32B composed of B'and a support member 32B "is provided, and the rolling member 32B 'is composed of balls 32A1, 32A2, 32A3 and ball receivers 32A4, 32A5, 32A6. The support member 32B "is composed of leaf springs 32A7, 32A8, 32A9. In addition, the rolling member 32B 'and the supporting member 32
Although there are three B ″ s, the distance between them may be shorter than the half between the H-plane inner walls 1C and 1D of the waveguide 1 as described above. In this case, the length of the space S3 in the H-plane direction. However, the leaking microwave can be shielded more effectively.

In each of the above-mentioned embodiments, the second microwave leakage prevention means is provided on the E-plane inner walls 1A and 1B side.
The second microwave leakage prevention means may be provided also on the in-plane walls 1C and 1D side.

[0028]

As described above, according to the invention described in claim 1, since there is almost no friction due to the contact between the second microwave leakage preventing means and the inner wall of the waveguide, the second microwave leakage is caused. The prevention means can stabilize the state in which the microwave leaking from the first microwave leakage prevention means is almost completely shielded. Also, when plasma processing,
Processing can be performed under constant conditions without affecting the plasma. Further, a product having a long life can be obtained without having an excessive function as a drive source of the movable short-circuit plate.

According to the second aspect of the present invention, the microwave leaking from the first microwave leakage preventing means is shielded even if the second microwave leakage preventing means has a small number of parts. It is possible to reduce the space formed by the second microwave leakage prevention means, which is effective to achieve this, from the E-plane inner wall of the waveguide and the movable short-circuit plate.

Further, according to the invention described in claim 3,
In particular, the structure of the second microwave leakage prevention means is simplified and the rolling movement is performed while making point contact with the inner wall of the waveguide, so that the linear movement of the movable short-circuit plate can be made smoother.

[Brief description of drawings]

1A is a schematic configuration diagram showing a first embodiment according to the present invention, and FIG. 1B is a sectional view taken along line I-I of FIG.

FIG. 2A is a schematic configuration diagram showing a second embodiment according to the present invention, and FIG. 2B is a sectional view taken along line II of FIG.

3A is a schematic configuration diagram showing a conventional example, and FIG. 3B is a sectional view taken along line I-I of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Rectangular waveguide 2 Movable short-circuit plate 11 1st microwave leakage prevention means 22A, 22B, 32A, 32B 2nd microwave leakage prevention means 22A ', 22B', 32A ', 32B' Rolling member 22A ", 22B ", 32A", 32B "support member

Claims (3)

[Claims] 1. A non-contact type first microwave leakage prevention means having a microwave choke structure is provided on a movable short-circuit plate arranged inside a rectangular waveguide so as to be movable in the tube axis direction. A second microwave leakage prevention unit is provided which is in contact with the inner wall of the waveguide and shields microwaves leaking from the first microwave leakage prevention unit, and the movable unit is movable via the second microwave leakage prevention unit. In a microwave circuit element with a movable short-circuit plate, wherein a short-circuit plate and an inner wall of an electric field surface of the waveguide are electrically connected, the second microwave leakage prevention means includes a rolling member and a supporting member that supports the rolling member. A magnetic field of the waveguide in a portion where the rolling member is not in contact with the electric field surface inner wall and the movable short-circuit plate in a state where the rolling member is in contact with at least the electric field surface inner wall. Direction length, microwave movable shorting plate with a microwave circuit device which is less than 1/2 of the wavelength of the used. 2. The microwave circuit element with a movable short-circuit plate according to claim 1, wherein the rolling member comprises a roller and a bearing for rolling the roller. 3. The microwave circuit element with a movable short-circuit plate according to claim 1, wherein the rolling member includes a ball and a ball receiver for rolling the ball.