JPH0431201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a mode conversion device that performs conversion between a circular waveguide and a coaxial line using a rectangular waveguide.

(Prior Art) Conventional mode converters include coaxial/waveguide converters and rectangular/circular waveguide converters. The former is
It converts TE ₁₀ waves to TEM waves, and has a structure in which the center conductor of a coaxial line inserted into a waveguide is used as an antenna to transfer high-frequency power, and is used in the input stage of a microwave receiver. . The latter converts a rectangular waveguide into a circular waveguide, and is used in a rotary connection between a radar device antenna and a rectangular waveguide.

This circular/rectangular waveguide exhibits high-pass filter characteristics, and the wavelength at which the passing loss decreases to 3 dB is called the cutoff wavelength λ _c . TE ₁₀ in rectangular waveguide
The cutoff wavelength λ _c in the mode is expressed by the following equation, where a is the wide surface dimension of the rectangular waveguide.

λ _c = 2a ...(1) Generally, there are TE ₁₁ modes in a circular waveguide,
The cutoff wavelength λ _c is expressed by the following equation, where r is the radius of the circular waveguide.

λ _c =3.412r (2) Conventionally, in this type of rectangular circular waveguide converter, the cutoff wavelength of each waveguide is selected to be approximately the same in order to reduce conversion loss. On the other hand, satellite broadcasting
It uses a circularly polarized wave plane of 12GHz microwave.
A radio wave format with clockwise and counterclockwise polarization planes is created depending on the reception area, and two signals are transmitted in one frequency to make effective use of radio waves.

FIG. 2 is a perspective view of a conventional mode converter for receiving circularly polarized radio waves. This mode converter is comprised of a signal input port 1 of a waveguide, a polarization converter 2 for restoring the polarization plane, a coaxial output end 3, and a shorting plate 5. At the coaxial output end 3,
Since the center conductor 4 is inserted into the circular waveguide as an antenna, the internal electric field distribution can be prevented and the plane of polarization changes again, which increases conversion loss.

(Object of the Invention) An object of the present invention is to provide a mode conversion device that eliminates such drawbacks and reduces the influence of the center conductor of a coaxial line directly inserted into a circular waveguide.

(Structure of the Invention) The mode conversion device of the present invention includes a circular waveguide, a rectangular waveguide connected to the circular waveguide and having a diagonal dimension equal to or less than the diameter of the waveguide, and A coaxial line in which a center conductor is inserted into the center of a wide surface of a tube and an outer conductor is connected to the waveguide wall, and a short circuit plate provided at a position approximately 1/4 of the wavelength in the tube from the insertion point of the center conductor. Contains and consists of.

(Example) Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the present invention. In this embodiment, a circular waveguide 1 with a built-in polarization converter 2 is used.
and a rectangular waveguide 6 connected to the circular waveguide 1 and having a diagonal line having a dimension smaller than the diameter of the waveguide 1;
The center conductor 4 is inserted into the wide center tube of the rectangular waveguide 2, and the coaxial line 3 has an outer conductor connected to the waveguide wall, and from the point where the center conductor 4 is inserted, it is about 1/4 of the wavelength inside the tube. It is equipped with a short circuit plate 5 attached at the position.

When the diagonal dimension of the rectangular waveguide 6 becomes equal to or smaller than the inner diameter of the circular waveguide 1, inductance components of L and C are generated equivalently at these connecting parts, so that the opening of the rectangular waveguide becomes smaller. By selecting the size, a converter can be constructed without a taper or a conversion mechanism in the conversion part.

When we experimentally confirmed the characteristics of this converter, we found that
The results showed that the conversion loss was small when the cutoff frequencies of these waveguides were around the same, and that matching of the reflection characteristics was better when the aperture of the rectangular waveguide was made smaller.

In these embodiments, the TE ₁₁ mode wave propagating through the circular waveguide 1 is converted into the TE ₁₀ mode of the rectangular waveguide at the contact point between the circular waveguide 1 and the rectangular waveguide 6 . Since the rectangular waveguide 6 has different vertical and horizontal dimensions, it has the advantage that rotational modes and unnecessary modes are less likely to occur and conversion loss is reduced over a wide band.

(Effects of the Invention) As described above, according to the present invention, since a rectangular waveguide is used, rotation modes and unnecessary modes are less likely to occur, and conversion loss can be reduced.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a mode converter according to an embodiment of the present invention, and FIG. 2 is a partially exploded perspective view of a conventional mode converter consisting of a circular waveguide and a coaxial line converter. In the figure: 1...Signal input section, 2...Polarization converter, 3...
Coaxial output end, 4... Center conductor, 5... Short circuit plate, 6
. . . Rectangular wave waveguide, 7 . . . Tapered.

Claims (1)

[Claims] 1 A circular waveguide, a rectangular waveguide that is directly connected to this circular waveguide and whose diagonal line dimension is set to be less than the diameter of this circular waveguide, and a center conductor inserted in the center of the wide surface of this rectangular waveguide. A mode conversion device comprising: a coaxial line having an outer conductor connected to a waveguide wall; and a shorting plate provided at a position approximately 1/4 of the wavelength within the tube from the insertion point of the center conductor.