JP3030851B2 - Waveguide type filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide filter having an adjustment mechanism for adjusting electric characteristics, and more particularly to a waveguide filter suitable for use in a millimeter wave band.

[0002]

2. Description of the Related Art FIGS. 12 and 13 show examples of the structure of an adjusting mechanism in a conventional waveguide filter of this kind. These adjustment mechanisms adjust, for example, electrical characteristics of the waveguide in the millimeter wave band, such as VSWR, bandwidth, attenuation characteristics, insertion loss, and the like. And a screw which is displaced in the axial direction connecting the inner surface of the tube and whose distal end is exposed from the inner wall surface to the space in the pipe.

FIG. 12 shows an example of an adjusting mechanism using a metal screw, and FIG. 13 shows an example of an adjusting mechanism using both a metal screw and a dielectric. The adjustment mechanism of FIG. 13 can reduce the amount of adjustment more than that of FIG.

[0006] The adjusting mechanism 80 shown in FIG. 12 is configured such that a space 7 in a pipe between a pair of susceptance elements (windows) 2 opposed to each other.
In addition, a structure is provided in which the tip of the screw 85 protrudes. The susceptance elements 2 make the admittance of the tube space 7 inductive, and a plurality of the susceptance elements 2 are provided at predetermined intervals in the tube axis direction. The screw 85 is provided to reduce the inductive susceptance and adjust the VSWR, the bandwidth and the like depending on the insertion position. The adjusting mechanism 80 having such a structure is similarly provided at the maximum electric field between the other susceptance elements 2 in the tube axis direction for frequency adjustment. It is to be noted that a kind of resonator is formed by the tube space 7 in the tube axis direction divided by the susceptance element 2.

On the other hand, an adjusting mechanism 90 using a dielectric is
As shown in FIG. 13, a dielectric 94 is fixed to the tip of the screw 95 with an adhesive or the like, and the tip of the dielectric 94 is opposed to the pair of susceptance elements through the tap relief 97 and the integrated hole 98. It has a structure that protrudes into the pipe space 7 between the two. The adjusting mechanism 90 is also provided at the maximum electric field between the other susceptance elements 2 in the tube axis direction for frequency adjustment, as in the case of FIG. Reference 85
1, 951 is a screw groove, and 6 is a nut for fixing the screws 85, 95 after adjustment.

[0006] Each of the waveguide band pass filters has
The waveguide portion is formed by joining a pair of waveguide elements 1A and 1B mainly for convenience of processing. For example, FIG.
FIG. 4 is an exploded view of the waveguide portion of the waveguide band-pass filter having the adjusting mechanism 80 shown in FIG. In the example of FIG. 14, of the pair of waveguide elements 1A and 1B divided by a plane including the lines Y1-Y2 and Y3-Y4, a pair of susceptances are formed on the lower waveguide element 1B by counterboring or the like. A plurality of sets of the elements 2 are formed, and the upper waveguide 1A is joined to the lower waveguide 1B by screws 86. Each susceptance element 2
The adjustment screws 85a and 85b for the above-described electrical characteristics are inserted into the resonator portion formed by the pair of. The waveguide-type bandpass filter having the adjusting mechanism 90 shown in FIG. 13 has substantially the same structure.

[0007]

In the conventional waveguide band-pass filter, the screws 85 and 95 are rotated at the time of adjustment, so that poor contact is likely to occur at the roots of the screws 85 and 95. When a contact failure occurs, the effect is remarkably manifested in the millimeter wave band as a change in electrical characteristics such as VSWR, insertion loss, and attenuation. Further, when the electric characteristics are changed by adjusting the susceptance element 2, they are easily changed rapidly when the screw is rotated, and the adjustment is very difficult. It becomes remarkable as the frequency becomes higher even in the millimeter wave band. In particular, in the waveguide band-pass filter having the adjusting mechanism 90 having the structure shown in FIG. 13, an abnormal absorption phenomenon as shown in FIG. 17A and an abnormal resonance phenomenon as shown in FIGS. Electrical characteristics are not improved. FIG. 17 shows an example of a waveguide bandpass filter in the millimeter wave band with a center frequency of 89 GHz. The upper part shows return loss characteristics, the lower part shows attenuation characteristics, the horizontal axis represents frequency, and the vertical axis represents power level (dB). Is represented. A similar problem occurs when the VSWR is adjusted with another waveguide filter other than the bandpass filter.

Further, since a conventional waveguide type filter such as a band-pass filter is formed by joining a pair of waveguide elements, the current flow becomes poor near the junction, and the no-load Q
There is a disadvantage that o becomes small and insertion loss becomes large. That is, the current in each resonator in the waveguide flows along the tube wall as shown by the solid line in FIG. 15, but is guided on the plane including Y1-Y2 and Y3-Y4 as shown in FIG. Since the tube elements 1A and 1B are joined, a part of the current flow is cut off (cut off) at the joint. In this case, the no-load Qo is significantly reduced. Further, the adjusting mechanism 90 shown in FIG. 13 has a problem that the adjustment requires a considerable skill because the width of adjustment of the passing band width is small.

An object of the present invention is to provide a waveguide type filter having an improved adjustment mechanism which can easily and stably adjust electric characteristics.

[0010]

[0011] The onset light waveguide filter which solves the above described problems has an adjustment mechanism for adjusting the electrical characteristics of the waveguide, the adjustment mechanism the inner wall surface of the specific portion of the waveguide A waveguide filter comprising a movable conductor whose axial end is displaced in the axial direction connecting the inner wall surface and the outer wall surface, and a tip end of which is exposed from the inner wall surface to the inner space of the tube, wherein a side surface portion of the movable conductor and the waveguide A first cavity portion and a second cavity portion each having a start and end in the direction from the inner wall surface to the outer wall surface, and the first cavity portion is in a short-circuit state at the start end. The second hollow portion starting from the terminal end of the first hollow portion is open at the starting end, and the movable conductor whose diameter varies stepwise according to portions is inserted into a cylindrical space having the same diameter. And the difference between the diameter of the cylindrical space and the diameter of the movable conductor Wherein the first cavity portion and a second cavity is formed.

The distance between the beginning and the end of the first cavity and the beginning and the end of the second cavity are each n / 4 (n is an odd natural number: usually "1") of the free space wavelength. In addition, the impedance of the second cavity from the beginning to the end is greater than the impedance of the first cavity from the beginning to the end.

Another waveguide type filter according to the present invention has an adjusting mechanism in which a dielectric film is formed on at least a contact surface between the movable conductor and the first and second cavities.
Thereby, the contact between the movable conductor and the waveguide wall can be reliably prevented, and the characteristic impedance of the first cavity can be reduced.

In another waveguide type filter according to the present invention, two or more pairs of the first cavity portion and the second cavity portion are formed continuously from the inner wall surface to the outer wall surface. The first cavity has an adjustment mechanism starting from the inner wall surface.

[0015] In the waveguide type filter described above, the individual
A plurality of adjustment mechanisms may be provided in the adjustment target portion . Use at least one adjuster to adjust the resonance frequency.
A movable end of the structure is provided so as to point to a maximum electric field position in the waveguide. On the other hand, in a device used for adjusting the VSWR or the like, the tip of the movable conductor of at least one adjusting mechanism is provided at the minimum electric field position, specifically, in parallel with the susceptance element.

The waveguide is formed, for example, for convenience of molding.
A pair of waveguide elements are joined at a formation site of the first cavity. A susceptance element is formed at a predetermined position on at least one narrow surface of the facing end of each waveguide element. The movable conductor weakens an inductive susceptance formed by the susceptance element.

A support plate is provided at the opposite end of each waveguide element.
Each waveguide element is sandwiched by the support plate .
Unishi Ru by suppressing discontinuities current Te. When the waveguide has a resonator formed inside and a flange formed at an end, each waveguide element is preferably divided at the portion of the resonator.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a bandpass filter adjusting mechanism will be described below in detail with reference to the drawings. (First Embodiment) FIG. 1 is a sectional structural view of an adjusting mechanism 10 according to a first embodiment, and corresponds to FIGS. 12 and 13 showing a conventional example. The same elements as those in FIG. 12 are denoted by the same reference numerals.

In this adjusting mechanism 10, a pair or a plurality of pairs of susceptance elements (windows) 2 facing each other are formed in a predetermined portion of the waveguide 1 by counterboring or the like.
A tube space 7 is formed by these susceptance elements 2. The distal end of a screw 51 for adjusting electrical characteristics is exposed in the tube space 7. Reference numeral 511
Is a thread groove of the screw 51.

The tip of the screw 51 is located at the maximum electric field when adjusting the resonance frequency, and is aligned with the minimum electric field, specifically, each susceptance 2 when adjusting the VSWR and the like. Usually, both are provided side by side, and one end is exposed from the upper part of the pipe space 7 and the other is exposed from the lower part of the pipe space 7. In any case, the screw 51 is displaced in the axial direction connecting the inner wall surface and the outer wall surface of the specific portion of the waveguide 1. Normally, the tip of the screw 51 is fixed by the nut 6 at the position flush with the inner wall surface or at a position protruding from the inner wall surface toward the pipe space 7 by a certain length α. In the case of adjusting the resonance frequency, the tip of the screw 51 may be located substantially at the center between the susceptance elements 2 in the TE101 mode (mode where the maximum electric field is one at resonance), and in the TE102 mode (two electric field maximum at resonance). In this mode, the position is about λgo (λgo is the guide wavelength) / 4 from the susceptance element 2. Between the side surface of the screw 51 and the tube wall of the waveguide 1,
A first cavity portion 3 and a second cavity portion 4 each having a start and end in the direction from the inner wall surface to the outer wall surface of the waveguide 1 are formed.
In the case of the illustrated example, each cavity 3 has a coaxial annular cross section, but this shape may be arbitrary.

The starting end of the first cavity 3 is the inner wall surface X of the waveguide 1.
It is 0, and the length is 11 until the end. The end of the first cavity 3 is also the start of the second cavity 4 in the screw axis direction, and the length of the second cavity 4 is 11 until the end of the second cavity 4 in the screw axis direction. These lengths l1 are
Both have an electrical length of about 90 degrees, for example, about λo (free space wavelength) / 4. The characteristic impedance of the first cavity 3 is Z1, and the characteristic impedance of the second cavity 4 is Z2.
And Z2 is made as large as possible than Z1. In the present embodiment, each of the cavities 3, 4 is set so as to be about "2" or more.
The size is designed.

The operation of the adjusting mechanism 10 having the above structure is as follows. FIG. 6A is a partially enlarged view near the screw 51, and FIG. 6B is an equivalent circuit of the portion. In terms of electrical length, the first hollow portion 3 has an electrical length of θ1, and the second hollow portion 4 has an electrical length of θ2. These electric lengths θ2 and θ1 are about 90 degrees as described above. The impedance ZB when viewing the point C from the illustrated point B is jZ2tanθ2, and the impedance ZA when viewing the point B from the illustrated point A is jZ1 ｛(Z2tanθ).
2 + Z1 tan θ1) / (Z1−Z2 tan θ2 · tan θ)
1) The characteristic impedance ratio “Z2 / Z” represented by｝
Since “1” is about “2” or more, if the C end is set to about 0Ω, the impedance ZB becomes very large, while the impedance ZA becomes a very small value.

That is, the impedance ZA when the screw 51 is viewed from the point X0 in FIG. 1 is substantially short-circuited, and the impedance ZB when the X2 point is viewed from the point X1 is substantially open. It becomes difficult to enter the screw 51 side, and the influence of poor contact near the root of the screw 51 is eliminated. Therefore, the adjustment of the electrical characteristics becomes easier as compared with the conventional adjustment mechanism. In particular, by employing the structure of this embodiment, it becomes possible to realize a bandpass filter at a practical level of a millimeter-wave band waveguide having a very high frequency.

The above operation is described for convenience only with the screw 5
Although 1 is an example of one case, the same description holds true for the case where the electric field maximum portion in the resonator and the susceptance element 2 are arranged in parallel.

(Second Embodiment) FIG. 2 is a sectional structural view of an adjusting mechanism 20 according to a second embodiment, and the same elements as those in the first embodiment are denoted by the same reference numerals.
The adjusting mechanism 20 differs from the adjusting mechanism 10 of the first embodiment in that the end conductor portion 522 uses a thinner screw 52 than the conductor portion near the outer wall of the waveguide. This is the point that a second hollow portion 41 having the same diameter as the vicinity of the portion is provided. The diameter of the first hollow portion 3 is the end conductor portion 5 of the screw 52.
Slightly larger than the diameter of 22. Reference numeral 521 is
This is a screw groove formed in a conductor portion of the screw 52 near the waveguide outer wall.

FIG. 7A is an enlarged view of a part near the screw 52, and FIG. 7B is an equivalent circuit of the part. The first cavity 3 has an electrical length of θ1, and its characteristic impedance is Z
1, the second cavity 41 has an electrical length of θ2, and its characteristic impedance is represented by Z2.
The impedance ZB when the point C is viewed from the point is jZ2tanθ2,
The impedance ZA when the point B is viewed from the point A is jZ1Ｚ (Z
2tanθ2 + Z1tanθ1) / (Z1−Z2tanθ2 · tan)
θ1)｝, C end is about 0Ω, electrical length θ2
θ1 is about 90 °, and the impedance ratio Z2 / Z1 is about “2”.
The above is the same as in the first embodiment.

By employing the adjusting mechanism 20 having such a structure, the impedance ZA becomes as close to 0Ω as possible and the impedance ZB becomes almost infinite. Therefore, the same effect as the adjusting mechanism 10 of the first embodiment can be obtained. Note that the shapes of the first hollow portion 3 and the second hollow portion 42 are not limited to those shown in the drawing, as in the case of the first embodiment.

(Third Embodiment) FIG. 3 is a sectional structural view of an adjusting mechanism 30 according to a third embodiment. This adjustment mechanism 3
0 is different from the above-described adjusting mechanisms 10 and 20 in that the screw 53 in which the end conductor portion 533 and the conductor portion near the waveguide outer wall portion have the same diameter and the intermediate portion 532 is locally thin. In that, the spaces for forming the first cavity 32 and the second cavity 42 have substantially the same diameter, and the respective cavities 32 and 42 are formed by the relative positions of the screws 53. It is a point. That is, the diameter of the end conductor portion 533 of the screw 53 is slightly larger than the diameter 532 of the space portion, whereby the first hollow portion 32 is formed. Reference numeral 521 is a thread groove formed in a conductor portion near the outer wall of the waveguide.

The first cavity 32 has an electrical length of θ1 and its characteristic impedance is represented by Z1. The second cavity 42 has an electrical length of θ2 and its characteristic impedance is represented by Z2. , The impedance ZB when viewed from the beginning to the end of the second cavity 42 is jZ2tanθ2, A
The impedance ZA when the point B is viewed from the point is jZ1 ｛(Z2t
anθ2 + Z1tanθ1) / (Z1-Z2tanθ2 · tanθ)
1) The end of the second hollow portion 42 is approximately 0
As in the first embodiment, Ω, the electrical lengths θ2, θ1 are about 90 °, and the characteristic impedance ratio Z2 / Z1 is about “2” or more.

In the adjusting mechanism 30 having such a structure, the impedance ZA is as close as possible to 0Ω, and the impedance ZB is almost infinite. Therefore, the same effect as the adjusting mechanism 10 of the first embodiment can be obtained. Further, there is an advantage that the processing of the waveguide 1 for forming the hollow portions 32 and 42 is easier than the case where the adjusting mechanisms 10 and 20 of each embodiment are employed.

(Fourth Embodiment) FIG. 4 is a sectional structural view of an adjusting mechanism 40 according to a fourth embodiment. This adjustment mechanism 4
Reference numeral 0 denotes a partially modified configuration of the adjustment mechanism 20 according to the second embodiment. The difference from the adjusting mechanism 20 of the second embodiment is that a screw 54 having a longer end conductor portion 542 is used, and two sets of a first hollow portion and a second hollow portion are provided. Reference numeral 541 is a thread groove formed in the conductor near the outer wall of the waveguide.

The first cavities 3A and 3B have a length of 11 (electrical length is θ1), and their characteristic impedances are Z.
It is represented by 1. The second cavity 4B also has a length of 11 (electrical length θ2), the other second cavity 4A also has an electric length of approximately 11 and the characteristic impedance is represented by Z2. Impedance Z as viewed from the beginning to the end of the second cavities 4A, 4B
B is jZ2tanθ2, and the impedance ZA as viewed from the beginning to the end of the first cavities 3A and 3B is jZ1 ｛(Z2tanθ).
2 + Z1 tan θ1) / (Z1−Z2 tan θ2 · tan θ)
1) The end portions of the second hollow portions 4A and 4B are approximately 0Ω, the electrical lengths θ2 and θ1 are approximately 90 °, and the characteristic impedance ratio Z2 / Z1 is approximately “2” or more. This is the same as in the second embodiment.

In the adjusting mechanism 40 having such a structure, the first
The impedance ZA in the cavities 3A and 3B is as close to 0Ω as possible, and the impedance ZB in the second cavities 4A and 4B is almost infinite. Therefore, the second
The same effect as that of the adjusting mechanism 20 of the embodiment can be obtained, and further, as described above, the first hollow portions 3A and 3B and the second hollow portion 4
By providing two sets of A and 4B, the effect becomes more remarkable.

In order to facilitate the processing for forming the cavities 3A, 3B, 4A, 4B, two waveguide elements 1
When A and 1B are joined to form one waveguide 1,
A space for the cavity is formed in each of the waveguide elements 1A and 1B, and the joint is defined as the end of the second cavity 4B. By doing so, the influence on the no-load Qo due to the partial interruption of the current flow can be reduced.

Although this embodiment is an example in which two sets of the first and second cavities are formed, two or more sets formed by the same principle are also within the scope of the present invention.

(Fifth Embodiment) FIG. 5 is a sectional structural view of an adjusting mechanism 50 according to a fifth embodiment, in which a part of the configuration of the adjusting mechanism 20 of the second embodiment is modified. The difference from the adjusting mechanism 20 of the second embodiment is that the end portion 553 of the screw 55 is set in the direction of the narrow surface of the waveguide element 1A.
This is a point which can be fixed at 51 or the like. Reference numeral 5
Reference numeral 52 denotes a thread groove of the set screw 551.

At the time of adjustment, the torsion screw 551 is loosened to adjust the position of the end portion 553 of the screw 55, and when the position is determined, the torsion screw 551 is tightened. The characteristic impedance Z1 of the first cavity 3 and the characteristic impedance Z2 of the second cavity 4 are similar to those of the waveguide bandpass filter 20 of the second embodiment. The adjustment mechanism 50 according to this embodiment is particularly effective when the number of stages as a filter is small.

(Sixth Embodiment) FIG. 8 shows that in the adjusting mechanism 20 of the second embodiment, a dielectric film 523 is provided on a portion of the surface of the end portion 522 of the screw which comes into contact with the first hollow portion 3.
FIG. 4 is a sectional structural view of an adjustment mechanism 60 in which is formed. FIG. 9 shows an adjustment mechanism in which a dielectric film 534 is formed on a part of the surface of the end conductor portion 533 that contacts the first cavity 32 and the second cavity 42 in the adjustment mechanism 30 of the third embodiment. 70 is a sectional structural view of FIG. For the dielectric films 523 and 534, for example, Teflon having a relative dielectric constant εr of about 2.3 can be used.

By forming the dielectric films 523 and 534 as shown, the end conductor portions 522 and 533 can be reliably prevented from contacting the waveguide wall, and the first hollow portions 3 and 534 can be prevented.
32, the characteristic impedance Z1 can be further reduced, and the effect of the present invention can be made more remarkable.

Hereinafter, this will be described in detail. For example, in the example of FIG. 9, when the dielectric film 534 is not formed, the characteristic impedance Z1 of the first cavity 32 is 60
· It is expressed by ln (φb / φa). Here, φa is the diameter of the end conductor portion 533, and φb is the inner diameter of the space (the inner diameter of the second hollow portion 42). On the other hand, the relative permittivity εr is 2.
Characteristic impedance Z when 3 Teflon is formed
1 ′ is 60 · ln (φb / φa) / √ (εr) (Ω)
And becomes smaller than Z1.

When the dielectric film 534 is formed, the higher-order mode cutoff frequency fc is lowered, so that the end conductor portion 53
It is necessary to reduce the outer diameter φa and the inner diameter φb of the space to some extent. For example, in the example of FIG. 9, the higher mode cutoff frequency fc (GHz) when the dielectric film 534 is not formed.
Is represented by 190.8 / (φa + φb). φa is 1
mm and φb are 1.2 mm, the high-order mode cutoff frequency fc is about 86 (GHz), but the relative dielectric constant εr is 2.
High-order mode cutoff frequency f when Teflon No. 3 is formed
c ′ is 190.8 / ((φa + φb) · √ (εr))
And the higher-order mode cutoff frequency fc ′ is about 57 (GH
z). To obtain a higher-order mode cutoff frequency fc ″ of about 83 (GHz), φa is set to 0.6 mm and φb is set to 0.9.
mm, φa is 0.5 mm and φb is 0.7 mm in order to obtain a higher-order mode cutoff frequency fc ″ of about 104 (GHz).
mm.

(Overall Structure) Next, an example of the overall structure of a waveguide band-pass filter having the adjusting mechanisms 10 to 70 of the above embodiments will be described. The waveguide band-pass filter can be applied to various structures.
FIG. 10 is an exploded perspective view showing one example. In the illustrated example, a pair of waveguide elements 1C and 1D formed integrally with the half surface of the flange are joined to form a waveguide bandpass filter. Either or both waveguide elements 1
A plurality of susceptance elements 2 are formed in the tube axis direction on the narrow surface side inside C and 1D by counterbore processing. Further, on the wide surface side inside the waveguide elements 1C and 1D, there are electric characteristics adjusting devices. Screw grooves 511a and 511b for inserting the plurality of screws 51a and 51b. At the time of assembling, the waveguide elements 1C and 1D are held down from the left and right outer sides by the reinforcing plates SC and SD and screwed. As a result, a plurality of resonators and screws 5 are provided in the tube space separated by the susceptance element 2 respectively.
An adjustment mechanism including 1a and 51b is formed. The screws 51a and 51b are for adjusting the resonance frequency and for adjusting the VSWR and the like, respectively.

In the waveguide type bandpass filter having such a structure, the dimensional accuracy of the waveguide elements 1C and 1D can be maintained at a certain level or more, the characteristic variation is small, and a predetermined susceptance amount can be easily obtained. As a result, a waveguide-type bandpass filter whose electric characteristics can be easily adjusted can be obtained.
In addition, by adopting the structure as shown in the figure, the amount of cutting off the current at the joint surface becomes very small, so that the reduction of the no-load Qo is suppressed. According to actual measurements, insertion loss, amplitude deviation, etc.
It has been found that the improvement is at least about 20% over that of the conventional type in which the waveguide elements are simply joined. FIG.
FIG. 17 is a graph showing actual measurements of electrical characteristics of the waveguide bandpass filter. Compared to the electrical characteristics of a conventional waveguide bandpass filter measured under the same conditions (FIG. 17), abnormal absorption phenomena and abnormal resonance occur. The phenomenon is gone.

FIG. 11 shows a structure of a waveguide type bandpass filter in which only a resonator body is joined without including a flange portion when joining a pair of waveguide elements with a reinforcing plate. (A) is a top view, (b)
Is a side view, (c) is a rear view, and (d) and (e) are side views. Reference numerals 1E, 1F are waveguide elements, SC1, SD
Reference numeral 1 denotes a reinforcing plate, SC2 denotes a reinforcing plate holding screw, and SC3 denotes a waveguide holding screw.

In the illustrated waveguide band-pass filter, flanges F1 and F2 are integrally formed on one waveguide element 1E, and only a resonator component is formed on the other waveguide element 1F. At the same time, these are configured to be pressed from outside by the reinforcing plates SC1 and SD1. One waveguide element 1E
F1 to the other waveguide element 1F
May be formed integrally, and these may be joined and pressed.

In the waveguide bandpass filter having such a structure, the tap strength of the flanges F1 and F2 can be increased. According to actual measurements, it has been found that it can sufficiently withstand an impact of about 1000 G. Also, sufficient resistance to thermal shock cycle and vibration test can be obtained.

The present invention is as described above, but based on the same principle, a waveguide type filter other than a band-pass filter,
For example, the present invention can be similarly applied to a low-pass filter and a high-pass filter. The present invention can be similarly applied to frequency bands other than the millimeter wave band. As for the number of filter stages, FIG. 10 shows an example of a three-stage filter, and FIG. 11 shows an example of an eight-stage filter. It is a good thing.

[0048]

As is apparent from the above description, according to the present invention, there is a specific effect that the electrical characteristics at the time of adjustment are stabilized. Therefore, the electric characteristics can be easily adjusted even by non-experts, the VSWR is good, the insertion loss is small, and the abnormal absorption phenomenon and the abnormal resonance phenomenon are eliminated, so that the value as a product can be enhanced.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of an adjustment mechanism of a waveguide band-pass filter according to a first embodiment.

FIG. 2 is a sectional structural view of an adjustment mechanism of a waveguide band-pass filter according to a second embodiment.

FIG. 3 is a sectional structural view of an adjustment mechanism of a waveguide band-pass filter according to a third embodiment.

FIG. 4 is a sectional structural view of an adjustment mechanism of a waveguide band-pass filter according to a fourth embodiment.

FIG. 5 is a sectional structural view of an adjustment mechanism of a waveguide band-pass filter according to a fifth embodiment.

6A is a partially enlarged view of an adjusting mechanism, and FIG. 6B is an equivalent circuit thereof.

7A is a partially enlarged view of another adjustment mechanism, and FIG. 7B is an equivalent circuit thereof.

FIG. 8 is a sectional structural view of an adjustment mechanism of a waveguide band-pass filter according to a sixth embodiment.

FIG. 9 is a sectional structural view of an adjustment mechanism of another waveguide-type bandpass filter according to the sixth embodiment.

FIG. 10 is an exploded perspective view of a waveguide bandpass filter to which the present invention is applied.

FIGS. 11A to 11E are external views of another waveguide type bandpass filter using a reinforcing plate.

FIG. 12 is a sectional structural view of an adjustment mechanism of a conventional waveguide band-pass filter.

FIG. 13 is a sectional structural view of another adjusting mechanism of the conventional waveguide band-pass filter.

FIG. 14 is an exploded perspective view of a conventional waveguide band-pass filter.

FIG. 15 is an explanatory diagram showing a current flow in the TE101 mode in the resonator.

FIG. 16 is an actual measurement diagram of electrical characteristics of a waveguide band-pass filter to which the present invention is applied.

FIG. 17 is an actual measurement diagram of electrical characteristics of a conventional waveguide band-pass filter.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 waveguide 1A, 1B, 1C, 1D, 1E, 1F waveguide element 2 susceptance element (window) 3, 3A, 3B, 31, 32 first cavity 4, 4A, 4B, 41, 42 second cavity Part 51,51a, 51b, 52,53,54,55,85,95 Adjustment screw (movable conductor) 6 Nut 7 Tube space 10,20,30,40,50,60,70,80,90 Adjustment mechanism 523,534 Dielectric film SC, SD, SC1, SD1 Reinforcement plate F1, F2 Flange

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 1/207 H01P 7/06 H01P 5/04 H01P 3/12

Claims (10)

(57) [Claims] An adjusting mechanism for adjusting electrical characteristics of a waveguide, the adjusting mechanism being displaced in an axial direction connecting an inner wall surface and an outer wall surface of a specific portion of the waveguide, and having a tip portion thereof. Is a waveguide-type filter comprising a movable conductor exposed from the inner wall surface to the space in the tube, wherein between the side surface portion of the movable conductor and the tube wall of the waveguide, First with start and end in the direction of the wall
A cavity portion and a second cavity portion are formed, wherein the first cavity portion is in a short-circuit state at a start end thereof, and the second cavity portion having a start end of the first cavity portion is in an open state at a start end thereof. None, In the cylindrical space of the same diameter, the movable conductor whose diameter varies stepwise according to the part is inserted, and the first cavity portion and the movable member are determined by the difference between the diameter of the cylindrical space and the diameter of the movable conductor. A waveguide type filter, wherein a second cavity is formed. 2. A free space wavelength having a center frequency of n between a start end of the first cavity and a start end of the second cavity.
/ 4 (n is an odd natural number) and the impedance of the second cavity from the beginning to the end is:
Characterized in that said from the beginning of the first cavity greater than the impedance seen an end direction, claim 1 Symbol placement waveguide type filter. 3. The waveguide filter according to claim 2 , wherein a dielectric film is formed at least on a contact surface between said movable conductor and said first and second cavities. 4. A combination of the first cavity portion and the second cavity portion is formed continuously from the inner wall surface toward the outer wall surface in two or more sets.
The waveguide type filter according to claim 2 , wherein the first set of the first hollow portions starts from the inner wall surface. 5. A plurality of said adjusting machines for each adjustment target part
The waveguide according to any one of claims 1 to 4 , wherein a structure is provided , and a tip of the movable conductor of at least one adjustment mechanism is directed to a maximum electric field position in the waveguide. Type filter. 6. A plurality of adjusting machines are provided for each adjustment target portion.
Configuration is provided, the tip portion of the movable conductor at least one adjustment mechanism, characterized in that it is directed to and susceptance elements juxtaposed an electric field minimum position of the waveguide, according to claim 1 to 4 13. The waveguide type filter according to any one of the above items. 7. The waveguide is formed by joining a pair of waveguide elements at a position where the first cavity is formed, and a predetermined position on at least one narrow surface side of the opposing ends of each waveguide element. 7. The waveguide type filter according to claim 6 , wherein the susceptance element is provided, and the movable conductor weakens a susceptance formed by the susceptance element by an insertion amount into the waveguide. . 8. A support plate interposed the opposite ends of each waveguide element, characterized in that said each waveguide element is sandwiched by the support plate, the waveguide according to claim 7, wherein Type filter. 9. When the waveguide has a resonator formed inside and a flange formed at an end, each waveguide element is joined at a portion of the resonator. The waveguide type filter according to claim 7, wherein 10. A functions as a band-pass filter in the millimeter wave band, according to claim 1 to 9 or a waveguide filter according section.