JPH0434564Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a microwave waveguide, and more specifically, a cylindrical flexible waveguide that excludes the resonant frequency of the trapped TE _11o mode from the operating band. Regarding.

[Conventional technology]

Waveguides can be broadly classified into rectangular waveguides and cylindrical waveguides, and each type includes flexible waveguides and non-flexible waveguides. FIGS. 4a and 4b and FIG. 5 are diagrams showing examples of conventional waveguides.

In Figures 4a and 4b, rectangular waveguides 2,
A cylindrical-to-rectangular waveguide converter 3 is formed in a flexible cylindrical waveguide 1 having a diameter 2'. In addition, in FIG. 5, the cylindrical flexible waveguide 1' is formed to have a length of n·λg/2 (n: integer, λg: wavelength in the tube), and the cylindrical flexible portion is n·λg/2. It is designed to be a transformer for matching.

These cylindrical flexible waveguides 1, 1' have TE ₁₁ mode,
The rectangular waveguides 2, 2' transmit microwaves in TE ₁₀ mode.

When comparing a cylindrical flexible waveguide with a rectangular flexible waveguide, it is mechanically stronger.

Easy to manufacture.

It can be bent in any direction as shown in Figure 3b. (For a rectangular waveguide, it is limited to the direction intersecting the plane of the rectangular waveguide, as shown in FIG. 3a).

It has the following advantages.

Further, in a flexible cylindrical waveguide having rectangular waveguides at both ends as shown in FIGS. 4a, b and 5, the microwave electric field is in a fixed direction at the entrance and exit, which is convenient for use.

[Problem that the invention attempts to solve]

However, although the cylindrical flexible waveguide has the above-mentioned advantages, when it is bent, the TE _11o mode shown in FIG. 2a is excited. This TE _11o mode has the same cutoff wavelength λ _c as the TE ₁₁ mode shown in Figure 2b, and the electric field direction is TE ₁₁
Orthogonal to the mode. Note that dotted arrows in FIGS. 2a and 2b indicate lines of electric force. The above-mentioned TE _11o mode is transmitted without being interrupted in the cylindrical flexible waveguides 1 and 1' shown in FIGS. 4a, b and 5, for example.
Since it is not coupled to the rectangular waveguides 2 and 2', it is trapped in the cylindrical flexible waveguides 1 and 1', causing resonance between them. When the resonant frequency enters the usage band, the microwave loss increases or the waveguide 1,
The increase in the microwave electric field at waveguide 1' causes phenomena such as discharge, and the use of waveguides 1 and 1' becomes unbearable.

Therefore, in order to remove this resonant frequency from the usable band, the length l of the cylindrical flexible waveguides 1 and 1' must be adjusted. However, this design has to be done by trial and error because it is difficult to evaluate the internal wavelength λg of the cylindrical flexible waveguides 1, 1', the capacity of the junction of the cylindrical-rectangular waveguide converter 3, etc. , was extremely inefficient.

The present invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a cylindrical flexible waveguide that makes it possible to extremely easily remove the resonance frequency of the TE _11o mode trapped in the waveguide from the operating band. It is.

[Means for solving problems]

For this purpose, the microwave waveguide of the present invention is a cylindrical flexible waveguide having rectangular waveguides at both ends, and the microwave is transmitted through the tube to the entrance or exit of the cylindrical flexible waveguide. A resonant frequency adjustment post was installed to intersect the TE ₁₁ mode electric field lines.

〔Example〕

Hereinafter, a cylindrical flexible waveguide according to an embodiment of the present invention will be described. In FIG. 1, reference numeral 4 denotes a flexible cylindrical waveguide with rectangular waveguides 5, 5' connected to both left and right ends, and a resonant frequency adjustment post 6 protruding inward is attached to the entrance portion 4a of the flexible cylindrical waveguide. There is. The adjustment post 6 is oriented parallel to the lines of electric force in the TE _11o mode and intersects (orthogonal to) the lines of electric force in the TE ₁₁ mode, which is the transmission mode, and its insertion length h is It is installed so that it can be adjusted.

The adjustment post 6 mounted in this manner has almost no effect on the TE ₁₁ mode. By changing the insertion length h of the post 6, the parallel admittance can be changed and the value of the resonant frequency r can be greatly changed.

This resonant frequency r does not need to be particularly considered at the design stage, and by changing the insertion length h of the post 6 after manufacture, the resonant frequency r can be removed from the usable band of the flexible cylindrical waveguide 4.

Note that the adjustment post 6 may be installed at the outlet portion 4b of the flexible cylindrical waveguide 4.

[Effect of idea]

From the above, according to the present invention, since the resonant frequency adjustment post is attached to the inlet or outlet of the cylindrical flexible waveguide, it is possible to avoid complicating the design of the cylindrical flexible waveguide, and to avoid complicated operations. The resonant frequency can be easily removed from the usage band of the flexible cylindrical waveguide.

[Brief explanation of the drawing]

FIG. 1a is a front view of a waveguide according to an embodiment of the present invention;
Figure 1b is a cross-sectional view of the waveguide, Figure 2a is a cross-sectional view of the waveguide in which the TE _11o mode is excited, and Figure 2b is the TE ₁₁
A cross-sectional view of the waveguide in which the mode is excited, Figure 3a is an explanatory diagram of a rectangular flexible waveguide, Figure 3b is an explanatory diagram of a cylindrical flexible waveguide, and Figures 4a and b are conventional FIG. 5 is a front view of another conventional cylindrical flexible waveguide. 4... Flexible cylindrical waveguide, 4a... Inlet section, 4b
...Exit part, 5, 5'...Rectangular waveguide, 6...Resonance frequency adjustment post.

Claims (1)

[Claims for Utility Model Registration] (1) In a cylindrical flexible waveguide having rectangular waveguides at both ends, at the entrance or exit of the cylindrical flexible waveguide,
A waveguide for microwaves, characterized in that a resonant frequency adjustment post is attached so as to intersect the lines of electric force of the TE ₁₁ mode transmitted inside the pipe. (2) The microwave waveguide according to claim 1, wherein the resonant frequency adjustment post is formed of an adjustable rod-shaped body protruding into the cylindrical flexible waveguide. .