JP5394942B2 - Waveguide - Google Patents

Description

  The present invention relates to a structure of a waveguide, and more particularly, to a waveguide having a partition wall that partitions the front and rear in the middle.

Waveguides that guide electromagnetic waves are used in a variety of applications, but if the type of medium is different or the pressure is different in the middle of the waveguide, it is necessary to provide a partition that separates both media There is. For example, as shown in FIG. 2A, the partition wall 3 is formed in the middle of the waveguide 1 with a dielectric such as quartz glass having a diameter different from that of the waveguide 1. In this case, sealing is performed with a gasket or the like in order to prevent the medium from flowing around the partition.
However, the provision of such a partition wall 3 causes a problem that the propagation efficiency is deteriorated due to reflection of radio waves conducted in the waveguide at that portion.
For example, when a high-frequency signal is passed through a circular waveguide, there is a property that it cannot be propagated if the diameter of the waveguide is about half a wavelength or less. The frequency at which such a high-frequency signal cannot pass completely is called a cut-off frequency, and is characterized by the relationship between the effective wavelength of the high-frequency signal and the diameter of the waveguide.
Even if it does not go to the cut-off, if the propagation mode of the waveguide changes in the middle, reflection occurs at the interface, and the propagation efficiency decreases.
Such a problem is a problem of the shape of the waveguide 1 and the partition wall 3, that is, a discontinuity problem based on the shape of the interface between the medium and the dielectric in the waveguide 1. As a measure for solving such a problem, as shown in FIG. 3, a method of connecting a conical dielectric 4 to a partition wall 3 to improve the discontinuity of the interface and reducing the reflection of radio waves has been conventionally known. It has been. The following Patent Document 1 is an example.

With such a configuration, the discontinuity in the shape surface is considerably eliminated. However, as shown in FIG. 3, simply by placing the partition wall 3 perpendicular to the waveguide 1 in the waveguide 1, The partition wall 3 cannot be fixed in the waveguide 1, and the partition wall 3 moves freely in the waveguide 1, causing a practical problem that the mounting position is not fixed.
In order to improve this, it is desirable to make the outer diameter of the partition wall 3 larger than the inner diameter of the waveguide 1 as shown in FIG. However, if the outer diameter of the partition wall 3 is larger than the inner diameter of the waveguide 1 as described above, there is a problem that the signal is reflected at the step portion and the propagation efficiency is lowered.

  Japanese Patent Laid-Open No. 7-50515

If the structure as shown in FIG. 1 is used, the installation strength in the axial direction of the waveguide when the partition wall is mounted inside the waveguide is improved, but a partition step is inevitably generated. If the material of the dielectric 4 is kept the same, it cannot be solved that electromagnetic waves are reflected in the middle of the waveguide because of the discontinuity of the dielectric constant as shown in FIG.
Accordingly, the present invention has been created in view of the above circumstances, and a first object is to solve the problem of a decrease in propagation efficiency due to a change in the propagation mode of the waveguide. .
The problem of discontinuity based on the shape of the interface between the medium and the dielectric in the waveguide 1 as described above is also solved. This is the second problem.

In order to solve the above-described problem, the present invention is characterized in that a waveguide path for guiding a high-frequency signal is partitioned by a first dielectric having an outer diameter larger than the inner diameter of the waveguide path , in the second dielectric waveguide provided which is connected to the first dielectric through the contact surfaces of substantially equal outer diameter waveguide path inside diameter, effective high-frequency signal in the first dielectric The waveguide is characterized in that the ratio of the outer diameter of the first dielectric to the wavelength is equal to the ratio of the outer diameter of the contact surface to the effective wavelength of the high-frequency signal in the second dielectric. ing.
That is,
Λ, the wavelength of the high-frequency signal to be propagated in vacuum
The dielectric constant of the first dielectric is ε1,
The outer diameter of the first dielectric part is L1,
Let the dielectric constant of the second dielectric be ε2,
When the outer diameter of the contact surface of the second dielectric part is L2,
The effective wavelength of the high-frequency signal in the first dielectric is λ / √ (ε1), and the effective wavelength of the high-frequency signal in the second dielectric is λ / √ (ε2).
In the present invention, the ratio of the outer diameter of the first dielectric to the effective wavelength of the high-frequency signal in the first dielectric is equal to the ratio of the outer diameter of the contact surface to the effective wavelength of the high-frequency signal in the second dielectric. Because
{Λ / √ (ε1)} / L1 = {λ / √ (ε2)} / L2.
Here, λ is common to both sides, so
L1 · √ (ε1) = L2 · √ (ε2) (1)
That is, the present invention and the formula (1) are synonymous.
Note that the wavelength referred to here varies depending on the wavelength shortening effect (multiplied by 1 / √ε) when a dielectric band is filled in a circular waveguide. Wavelength is used as a parameter.
That is, in the present invention, the ratio between the effective wavelength and the waveguide diameter characterizes the thickness of the waveguide perceived by the radio waves, and thus the behavior of the radio wave propagation in the waveguide (propagation mode). It was adjusted so as not to become.
The second dielectric may be provided both before and after the first dielectric, or may be provided either before or after the first dielectric.
Also in the present invention, in order to solve the “problem of discontinuity based on the discontinuity of the dielectric constant at the interface between the medium and the dielectric in the waveguide 1”, the second dielectric is guided. It is desirable that the surface in contact with the medium in the wave tube (the surface opposite to the surface in contact with the first dielectric) is formed in a conical shape.
The second dielectric, by being configured in a cylindrical shape having an outer diameter equal to the inner diameter of the waveguide between the contact surface and the conical surface, and securely fixed to the waveguide Become.
Furthermore, the second dielectric may be detachable from the waveguide.

Waveguide path for guiding a high frequency signal of the present invention is partitioned by a first dielectric outer diameter larger than the inner diameter of the conductor wave path, the waveguide path, substantially equal to the outer diameter and the waveguide path inside diameter In a waveguide provided with a second dielectric connected to the first dielectric via a contact surface of the first dielectric, the first dielectric is external to the effective wavelength of the high-frequency signal in the first dielectric. When the waveguide is characterized in that the ratio of the diameter is equal to the ratio of the outer diameter of the contact surface to the effective wavelength of the high-frequency signal in the second dielectric, the above-described waveguide is used. The problem of a decrease in propagation efficiency due to a change in the propagation mode of the wave tube is solved.
Further, in the present invention, the surface of the second dielectric in contact with the medium in the waveguide (surface opposite to the surface in contact with the first dielectric) is configured in a conical shape. It is possible to prevent the problem of discontinuity based on the shape of the interface between the medium and the dielectric, that is, the deterioration of the propagation efficiency of the radio wave guided by such discontinuity.

Sectional drawing which shows the structure of the waveguide concerning one Embodiment of this invention. Sectional drawing which shows the structure of the conventional waveguide. The reference sectional view showing an example of the dielectric inserted in the waveguide. Sectional drawing which shows the structure of the waveguide concerning one Embodiment of this invention. Sectional drawing which shows the structure of the waveguide concerning one Embodiment of this invention.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings.

Hereinafter, the waveguide according to the embodiment of the present invention will be described with reference to FIG.
In all the figures, the graph is shown below with the inside diameter (diameter) of the waveguide / the effective wavelength in the waveguide on the vertical axis and the longitudinal direction of the waveguide on the horizontal axis.
In this waveguide 1, a waveguide path 2 that guides a high-frequency signal is divided forward and backward by a first dielectric 6. The waveguide path 2 is provided with second dielectrics 4 and 5 having outer diameters substantially equal to the inner diameter of the waveguide path 2 in a state of being connected before and after the first dielectric body 6. ing.
The surfaces of the second dielectrics 4 and 5 in contact with the medium in the waveguide 1 (surfaces opposite to the surface in contact with the first dielectric) 4 a and 5 a are perpendicular to the axis of the waveguide 1. However, in order to solve the “discontinuity problem based on the shape of the interface between the medium and the dielectric in the waveguide 1”, it is desirable to form a conical shape as illustrated.
In this embodiment, in order to solve the problem of a decrease in propagation efficiency due to a change in the propagation mode of the waveguide 1, the first dielectric 6 with respect to the effective wavelength of the high-frequency signal in the first dielectric 6 The ratio of the diameter L1 in the dielectric 6 and the ratio of the waveguide portion diameter L2 to the effective wavelength of the high-frequency signal in the second dielectric (4 and 5 or any of 4 and 5) are equal to each other. The material of the second dielectric is set.

This will be described in detail.
Λ, the wavelength of the high-frequency signal to be propagated in vacuum
The dielectric constant of the first dielectric is ε1,
The diameter of the first dielectric part is L1,
Let the dielectric constant of the second dielectric be ε2,
If the diameter L2 of the second dielectric part is
The effective wavelength of the high-frequency signal in the first dielectric is λ / √ (ε1), and the effective wavelength of the high-frequency signal in the second dielectric is λ / √ (ε2).
In this embodiment, the ratio of the diameter L1 of the first dielectric to the effective wavelength of the high frequency signal in the first dielectric 6 and the high frequency signal in either the second dielectric 4 and 5 or 4 and 5 is used. The ratio of the diameter L2 of the second dielectric to the effective wavelength is made equal.
That is,
{Λ / √ (ε1)} / L1 = {λ / √ (ε2)} / L2.
Here, λ is common to both sides, so
L1 · √ (ε1) = L2 · √ (ε2) (1)
That is, “the ratio of the diameter of the high-frequency signal in the first dielectric to the effective wavelength is equal to the ratio of the diameter of the second dielectric to the effective wavelength of the high-frequency signal in the second dielectric. What has been done and (1) are synonymous.
As a result, the propagation mode of the radio wave in the first dielectric 6 and the propagation mode of the radio wave in the second dielectrics 4 and 5 are made equal so that the propagation of the radio wave is not hindered. The decline is suppressed.

Note that the wavelength referred to here varies depending on the wavelength shortening effect (by 1 / √ε times) due to the dielectric when the circular waveguide is filled with a dielectric band. In this case, the effective wavelength is used as a parameter.
In other words, in this embodiment, the ratio between the effective wavelength and the waveguide diameter characterizes the thickness of the waveguide perceived by radio waves, and thus the behavior of radio wave propagation in the waveguide (propagation mode). It is adjusted so as not to be continuous.

  The second dielectrics 4 and 5 are preferably provided both before and after the first dielectric 6 as in this embodiment, but are provided either before or after the first dielectric. May be.

The second dielectrics 4 and 5 are connected to the first dielectric 6 as shown in FIGS. 1 and 4, but attaching to the first dielectric 6 by a method such as adhesion is a part thereof. This should be avoided because the propagation mode changes, or an adhesive that does not change the propagation mode should be used. When the adhesive is not used, the contact area between the second dielectrics 4 and 5 and the inner diameter portion of the waveguide 1 is set so that the second dielectrics 4 and 5 are not displaced inside the waveguide 1. It is desirable to enlarge it. As one of the methods, as shown in FIG. 4, the gap between the surface where the first dielectric and the second dielectric 4 and 5 are in contact with the conical surface is equal to the inner diameter of the waveguide. It is conceivable to form the cylindrical portion 7 having a diameter. By adopting such a structure, fixing to the waveguide is ensured.
In the above embodiment, as shown in FIGS. 1 and 4, the dielectric 4 and the cylindrical portion 7 are provided on both sides of the partition wall 3 in a conical shape. However, as long as slight reflection of electromagnetic waves can be allowed. As shown in FIG. 5, it is possible to provide the dielectric 4 and the cylindrical portion 7 only on one side of the partition wall 3, and such usage is an example of the present invention.

Furthermore, the second dielectric may be detachable from the waveguide.
For example, another waveguide (hereinafter referred to as connection waveguide) is connected to a part of the waveguide (hereinafter referred to as main waveguide), and a part of the electromagnetic wave propagating through the main waveguide is connected and guided. In the usage such as taking out with a wave tube, it is conceivable to use a connecting waveguide as an observation window. In this case, of course, when it is used as a viewing window, the propagation of electromagnetic waves is stopped.
In such a usage, when the electromagnetic wave is extracted from the connection waveguide, the second dielectric as described in this embodiment is attached to a part of the connection waveguide so that the electromagnetic wave can easily propagate. However, when used as a viewing window, there is no electromagnetic wave to propagate, so the second dielectric is not necessary, and the presence of the second dielectric may impair visibility as a viewing window . Therefore, it is desirable that the second dielectric is freely detachable from the connection waveguide. Further, in the case of the configuration shown in FIG. For example, in an application that is normally used as an observation window and transmits high frequency only when necessary, only the partition wall 3 is used as a transparent observation window and can be attached / detached only when transmitting high frequency. By using it, it is possible to obtain the characteristics of a low-loss waveguide without disassembling it. Such usage is also part of this invention.

  The present invention can be applied to various waveguide structures.

DESCRIPTION OF SYMBOLS 1 Waveguide 3 Partition 2 Waveguide path | route 4, 5 2nd dielectric material 6 1st dielectric material 7 Cylindrical part

Claims (5)

Waveguide path for guiding a high-frequency signal is separated by a first dielectric outer diameter larger than the inner diameter of the conductor wave path, the waveguide path, the contact surfaces of the outer diameter approximately equal the waveguide path inside diameter The ratio of the outer diameter of the first dielectric to the effective wavelength of the high frequency signal in the first dielectric in the waveguide provided with the second dielectric connected to the first dielectric via And the ratio of the outer diameter of the contact surface to the effective wavelength of the high-frequency signal in the second dielectric body is made equal. The second dielectric, the first dielectric waveguide according to claim 1 comprising provided either before or after the front and rear both or first dielectric. The waveguide according to claim 1 or 2 , wherein a surface of the second dielectric that contacts the medium in the waveguide is formed in a conical shape. The second dielectric waveguide according to claim 3, between the contact surface and the conical surface is formed in a cylindrical shape having an outer diameter equal to the inner diameter of the waveguide.   The waveguide according to claim 1, wherein the second dielectric is detachable with respect to the waveguide.

Images