JPS5932002B2 - coaxial waveguide converter - Google Patents

Description

Detailed Description of the Invention This invention relates to a coaxial waveguide converter in which one end of the inner conductor of a coaxial line is inserted into a rectangular waveguide as a probe, and in particular, to adjust the probe position to obtain good electrical performance. It is about the mechanism.

FIG. 1 is a sectional view showing an example of a conventional coaxial waveguide converter.

In the figure, 1 is a waveguide, 2 is a shorting plate provided at one end of this waveguide, 3 is an outer conductor of the coaxial line provided on the waveguide 1, 4 is an inner conductor of the coaxial line, and 5 is an insulator for fixing this inner conductor to the center of the outer conductor 3, 6 is a probe provided at the tip of the inner conductor 4, and γ is for adjusting the position of this probe with respect to the inner conductor 4. 8 is a coaxial drawing frame.

A conventional coaxial waveguide converter is constructed as described above, and the probe 6 provided at the tip of the inner conductor 4 of the coaxial line is vertically positioned by a screw mechanism 7 to perform electrical matching.

However, as mentioned above, since the probe only has a mechanism for adjusting the probe position in the vertical direction, it may be difficult to obtain good electrical customization at the desired frequency due to machining errors in the left and right positions of the elbows on the rectangular waveguide, and assembly force. However, there were drawbacks such as variations in custom-made products.

The present invention has been made to eliminate these drawbacks, and aims to provide a coaxial waveguide converter that is easy to adjust and has good electrical properties.

FIG. 2 is a cross-sectional view showing one embodiment of the present invention.
2.4 to 8 are exactly the same as the conventional device described above.

In the figure, 10 is a cylindrical pedestal provided on the E surface of the rectangular waveguide 1, 11 is a cylindrical conductor that fits inside this cylindrical pedestal and can be rotated and adjusted, and 12 is this cylindrical conductor 11. It is a cylindrical through hole having an axial center eccentric from the axial center of the cylindrical conductor 11 and provided in an axial direction parallel to the axial direction of the cylindrical conductor 11.

Since the inner surface of this through hole 12 constitutes the inner surface of the outer conductor of the coaxial line, the cylindrical conductor 11 will be referred to as the outer conductor 11 hereinafter.

In the coaxial waveguide converter configured as above,
The axial direction of the cylindrical pedestal 10 is perpendicular to the wide surface of the rectangular waveguide 1, and the distance between the axial center position and the shorting plate 2 is set at the first
The distance between the axial center position of the inner conductor 4 and the shorting plate 2 in the figure is approximately equal to the distance, and the outer conductor 11 is fitted into the circular base while maintaining a coaxial relationship.

An insulator 5 and an inner conductor 4 are placed within the through hole 12.

FIG. 3a is a perspective view of the outer conductor 11;
FIG. 4 is a plan view showing the relationship between the rectangular waveguide 1 and the outer conductor 11.

As shown in FIG. 4, when the outer conductor 11 is rotated, since the coaxial line is provided eccentrically, it shows a locus as shown by the dotted arrow.

Therefore, by rotating the outer conductor 11, the left and right positions can be adjusted, and the probe 6 can be moved up and down by the screw mechanism 1 to achieve alignment.

How the input admittance of the coaxial waveguide converter changes by changing the position of the probe will be explained using a mathematical formula.

FIGS. 5a and 5b are schematic diagrams showing the dimensions of each part of the coaxial waveguide converter. FIG. 5a is a view seen from the waveguide opening side, and FIG. 5 is a sectional view.

FIG. 6 is an equivalent circuit diagram of a coaxial waveguide converter.

In the figure, α is the coupling coefficient of the probe antenna, and Zeq is TEl.

The equivalent impedance of the rectangular waveguide for the mode, X is the probe glue actance, where Z.

is the circular impedance of the waveguide according to the conventional definition.

At this time, the impedance ZA seen from the end of the coaxial line is ZA-αZeq(sin"βx+jsinβx cos
βX) jX.

Therefore, if the % impedance of the coaxial line is ZOOAX, the matching condition can be expressed as in the following equation.

ZOOAX ”'αZ e q s t n 2βX
-jX=-jctZeq sinβXCO3βX plus Z COAX is a real number.

On the other hand, the admittance Yin seen from the waveguide side is expressed as follows when the quasi-plane is taken as the probe position.

Here, Z is the sum of the probe reactance and the coaxial line impedance connected in series with the probe reactance, and is expressed by the following equation.

Z=ZcoAx -jX In the above relational expression, Z is conventionally used as a custom-made waveguide impedance.

For convenience, Zeq is used instead of .

As is clear from the Yin equation above, the shorting plate 2 and the probe 6
When the distance 11x between Yin and
moves clockwise on a constant conductance.

Further, when the probe is moved away from the center of the waveguide, that is, when d is decreased, α is decreased, and the conductance of Yin can be decreased.

FIG. 1 is a Smith admittance chart showing how Yin changes with changes in X and d.

In the above embodiments, the case of a coaxial waveguide converter was explained, but the coaxial waveguide in a crystal detector, mixer, multiplier, etc. that requires a conversion function between waveguide mode and coaxial mode is not limited to this. It can also be used as a converter.

As explained above, this invention has a simple structure in which the inner conductor is provided eccentrically with respect to the center line of the outer conductor, and the position of the probe is changed to achieve good alignment between the rectangular waveguide and the coaxial line in a short time. Moreover, since adjustment is easy, strict machining accuracy is not required.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing an example of a conventional coaxial waveguide converter.
Fig. 2 is a sectional view showing an embodiment of the present invention, Fig. 3a,
b is a perspective view and a sectional view of the outer conductor of the embodiment shown in FIG.
The figure is a plan view showing the relationship between the rectangular waveguide and the outer conductor.
, b is a schematic diagram showing the dimensions of each part of the coaxial waveguide converter, FIG. 6 is an equivalent circuit diagram, and FIG. 7 is a Smith admittance chart. In the figure, 1 is a rectangular waveguide, 4 is an inner conductor of a coaxial line,
6 is a probe, γ is a screw mechanism, 1o is a cylindrical pedestal, 11
is the outer conductor.

Claims (1)

[Claims] 1. In a coaxial waveguide converter in which one end of the inner conductor of a coaxial line is placed as a probe in a rectangular waveguide with one end short-circuited, the axis position is a predetermined distance from the short-circuited end, and a cylindrical pedestal provided on the wide surface of the rectangular waveguide so that its axial direction is perpendicular to the wide surface of the rectangular waveguide; A cylindrical through hole having an axial center located eccentrically from the axial center of the cylindrical conductor and provided in an axial direction parallel to the axial direction of the cylindrical conductor; The inner conductor of the coaxial line is provided coaxially with the through hole as the inner surface of the outer conductor of the line;
A probe is attached to the tip of the inner conductor of this coaxial line protruding into the rectangular waveguide through a screw, and the axial position of the probe is adjusted by the screw, and the axis of the coaxial line is adjusted. A coaxial waveguide converter comprising means for adjusting the position of the core within the rectangular waveguide by rotating the cylindrical pedestal.