JP3508040B2 - Waveguide / coaxial converter - 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 / coaxial converter, and more particularly to a waveguide / coaxial converter using a step ridge used in a microwave circuit.

[0002]

2. Description of the Related Art A waveguide or a coaxial line is used for microwave transmission. Since the microwave propagation mode is different in the waveguide and the coaxial line, a waveguide / coaxial converter is required at the connection between the waveguide and the coaxial line.

FIG. 3 shows a conventional waveguide / coaxial converter.
The one using the antenna 7 as shown in FIG.
As shown in (B), there is one using a waveguide whose one end is terminated by using a step-shaped ridge 4.

In particular, the waveguide using a ridge-terminated waveguide shown in FIG. 3B is one in which the impedance is gradually changed by the ridge to match the coaxial line.
Unlike the antenna type, etc., it does not require Teflon material for insulating and supporting the coaxial line (the core of the coaxial line is directly connected to the metallic ridge), which is advantageous in terms of power resistance.
It has been mainly used as a waveguide / coaxial converter for high power.

As shown in FIG. 3 (B), the ridge 4 is formed in the center of the long side (width a) of the rectangular cross section of the rectangular waveguide, and has a step of width a ′ toward the end of the waveguide. , A metal of the same material as the waveguide is raised, the core of the coaxial line is connected to the highest step (end of the waveguide), and the coaxial line side (direction of arrow 11 in the figure) Then, the signal is taken out through the coaxial connector 3. A rectangular waveguide is connected in the direction of arrow 10 in the figure.

As shown in FIG. 3B, a single ridge is formed when the ridge is attached to only one of the long sides of the rectangular cross section of the waveguide, and as shown in FIG. The case where ridges are attached to both long sides of is called a double ridge. In addition to the step shape, the ridge has a slope shape that continuously increases.

As shown in FIG. 5 of Japanese Unexamined Patent Publication No. 2-35801, a connecting portion is a double ridge in the waveguide direction (direction of arrow 10 in the figure) and a coaxial line direction (direction of arrow 11 in the figure). A waveguide / coaxial converter using a slope-shaped ridge in which the connecting portion is a single ridge is disclosed.

However, in relation to the device to be connected, for example, a WRJ-120 waveguide (19.05 mm × 9.525 mm) normally used for the 12 GHz band is used in the 14 GHz band (14-14.5 GHz). There may be a need. In this case, the optimum ridge size may not exist. This is because the higher order mode (TE20 mode) causes reflection depending on the size of the ridge, and unnecessary resonance occurs in the band.

In FIG. 3B, the resonance condition of the TE20 mode of the WRJ-120 waveguide with respect to the ridge size is (b '/ b) cot (πa' / λc) + B / Y0-co.
t (π (a−a ′) / λc) = 0 where λc is the cutoff wavelength of the TE20 mode, and B / Y0 is the normalized susceptance.

FIG. 4 shows an example of the result calculated for the TE20 mode by this equation. The right vertical axis of the graph shown in FIG. 4 shows the cutoff frequency corresponding to λc / a for the WRJ-120 waveguide.

As can be seen from this graph, the cutoff frequency of the TE20 mode approaches the used band depending on the selection of the ridge size, and unnecessary resonance is generated. When a waveguide is used at a frequency higher than the recommended operating frequency, the value of a becomes relatively large (since a waveguide with a high recommended frequency is generally thin), λc / a becomes small, and TE20 mode cutoff is achieved. The frequency becomes higher. For example, a '/ a = 0.5
In the case of, the cutoff frequency of the TE20 mode is completely within the used band (14 to 14.5 GHz).

[0012]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As shown in FIG.
In order to eliminate unnecessary resonance in the E20 mode, the height b '(that is, b' / b) of the ridge or the width a'of the ridge is used.
(Ie a '/ a) needs to be changed. However, since both b ′ and a ′ are related to the characteristics (impedance matching) as a basic ridge type waveguide / coaxial converter, it is difficult to satisfy both the conditions of impedance matching and elimination of unnecessary resonance at the same time.

An object of the present invention is to provide a ridge-type waveguide / coaxial converter which simultaneously satisfies both the conditions of impedance matching and elimination of unnecessary resonance.

[0014]

A waveguide / coaxial converter using a ridge according to the present invention has a ridge for impedance matching and an inner surface of a long side surface on which the ridge is installed.
Te characterized in that it comprises a counterbore portion or ridges on both side parts of the ridge.

[0015]

The operation of the present invention is as follows.
Counterbore portions on opposite sides of the ridge are provided with counterbores to equivalently widen the height b of the waveguide, or ridge portions are provided on both side portions to provide the height b of the waveguide. Is narrowed equivalently.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the construction of an embodiment of a ridge type waveguide / coaxial converter according to the present invention. FIG. 1 (A) is a rectangular section of a rectangular waveguide of the embodiment having a counterbore portion. 2B is a cross-sectional view taken parallel to the long side, and FIG. 3B is a cross-sectional view taken parallel to the short side, and the same portions as those in FIGS.

In FIG. 1, the main body 1 basically constitutes a waveguide 2 and is an end portion thereof. The waveguides are connected in the direction of the arrow 10 shown, and the coaxial line is the coaxial connector 3
Is connected in the direction of arrow 11 shown.

The ridge 4 has the function of gradually converting the impedance in steps and matching with the coaxial line.
The width, height, and length of the ridge portion 4 are designed so as to obtain the best matching condition with respect to the transmission signal frequency.

In this case, no matter how the ridge 4 obtains the best matching condition for the transmission signal frequency, the TE2
There is no match for the 0 mode. Therefore , on both sides of the ridge portion 4, as shown in FIGS.
By providing the counterbore 5 as described above, the height b ″ of the ridge 4 equivalent to the TE20 mode is changed,
The TE20 mode cutoff frequency for each step is kept out of the vicinity of the used (transmitted signal) frequency.

FIG. 2 shows another embodiment of the present invention.
(A) is a cross-sectional view of the rectangular waveguide of the type having a ridge section taken parallel to the long side of the rectangular cross section, (B) is a cross-sectional view taken parallel to the short side, and the portion equivalent to FIG. The same reference numerals are used.
Protrusions 6 are provided on both side portions of the ridge portion 4 on the surface facing the ridge portion 4 to change the equivalent b ″ of the ridge 4 for the TE20 mode.

In FIGS. 1 and 2, the counterbore 5 and the raised portion 6 are drawn so as to be provided on both sides of the ridge 4, but if necessary, the counterbore 5 having a different depth t or different for each step. It goes without saying that the ridge 6 having the height t ′ or the counterbore 5 and the ridge 6 may coexist.

[0023]

As described above, according to the present invention, by providing a counterbore or a ridge on both sides of a ridge, both conditions of impedance matching and elimination of unnecessary resonance by elimination of higher-order modes can be satisfied at the same time. There is.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment of the present invention.

FIG. 3 is a sectional view of an example of a conventional waveguide / coaxial converter.

FIG. 4 is a graph of cutoff wavelength for TE20 mode of a WRJ-120 waveguide.

FIG. 5 is a cross-sectional view of another example of a conventional waveguide / coaxial converter.

[Explanation of symbols]

1 body 2 Waveguide 3 coaxial connector 4 ridge 5 counterbore 6 ridge

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Claims (4)

(57) [Claims] 1. A waveguide / coaxial converter using a ridge, the ridge performing impedance matching, and the ridge.
A waveguide / coaxial converter characterized by including a counterbore portion or a raised portion on both side portions of this ridge on the inner surface of the long side surface on which is installed . 2. The waveguide / coaxial converter according to claim 1, wherein the ridge rises stepwise toward the end of the waveguide. 3. A waveguide / coaxial converter according to claim 1, wherein the core of the coaxial line is connected to the highest step of the ridge. 4. The waveguide / coaxial converter according to claim 1, 2 or 3, wherein the connection to the coaxial line is made by a connector.