JP2006157486A - Coaxial waveguide transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coaxial waveguide transformer with improved electric characteristics and improved productivity with no adjustment by using no calibration screw and the like. <P>SOLUTION: A first waveguide 11 where a coaxial connector 21 as a coaxial transmission path is provided, a third waveguide 13 as a standard base tube, and a second waveguide 12 as an intermediate part between the first and the third waveguides 11, 13 are formed in a step shape. The characteristic impedance of the first waveguide 11 is so specified that it becomes substantially equal to the characteristic impedance of the coaxial connector 21. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a coaxial waveguide, and in particular, converts a coaxial transmission line (or coaxial connector) used for transmission of a high-frequency signal such as a microwave into a waveguide, and efficiently transmits the signal. It relates to a tube converter.

  Generally, a coaxial transmission line or a coaxial cable and a waveguide are used for transmission of an ultra-high frequency signal such as a microwave. In the coaxial transmission line or the coaxial connector, the central conductor and the surrounding outer conductor are formed in a coaxial shape to transmit a signal. On the other hand, the waveguide is a transmission line formed of a hollow metal, and electromagnetic waves of a specific mode are propagated through the transmission line.

  Since these coaxial cables and waveguides have excellent transmission efficiency, that is, they can be transmitted with minimum transmission loss, electronic measuring instruments and telecommunications equipment that handle high-frequency signals such as microwaves (hereinafter collectively referred to as electronic) Widely used). In such electronic equipment, a coaxial waveguide converter is used to efficiently connect or couple a coaxial transmission line (or coaxial connector) to the waveguide.

  When a coaxial waveguide converter is configured, the waveguide dimension (a dimension × b dimension) of the coaxial waveguide converter is set to the counterpart waveguide connected to the coaxial waveguide converter. It is common to match the dimensions (so-called standard tube dimensions). Since the waveguide having such dimensions is used, it is difficult to match the characteristic impedance of the coaxial transmission line and the waveguide even if the probe shape at the coaxial end is devised.

  The prior art of such a coaxial waveguide converter is disclosed in several technical documents. A waveguide coaxial converter and a waveguide matching circuit capable of adjusting impedance over a wide range from an inductive region to a capacitive region using a plurality of screws in the waveguide are disclosed (for example, see Patent Document 1). .) Further, a coaxial waveguide converter using a step-type waveguide impedance converter is disclosed (for example, see Patent Document 2).

JP-A-8-148911 (page 3-4, FIG. 1) Japanese Utility Model Publication No. 61-57701 (page 4, FIG. 1)

  However, according to the prior art as described above, a plurality of adjustment screws for impedance matching between the coaxial transmission line and the waveguide must be installed on the waveguide side. Generally, a waveguide device such as a coaxial waveguide converter requires a confidential structure. Therefore, by installing an adjustment screw for impedance matching, it is necessary to add a sealing work for maintaining the confidentiality of the screw hole portion of the impedance adjustment and adjustment screw. For this reason, there are problems or disadvantages that the number of man-hours for carrying out each construction increases and the production cost increases. Furthermore, conventionally, since the screw for impedance adjustment was used for the standard element tube, the electrical characteristics such as the return loss of the coaxial waveguide converter itself are restricted. For example, the return loss is about 13% of the specific bandwidth. About -30 dB.

  The present invention has been made in view of the above-mentioned problems of the prior art, and mainly aims to provide a coaxial waveguide converter that overcomes or reduces the problems of the prior art, that is, has improved productivity and electrical characteristics. Objective.

  In order to solve the above problems, the coaxial waveguide converter according to the present invention employs the following characteristic configuration.

(1) In a coaxial waveguide converter that converts a coaxial transmission line into a waveguide and transmits a high-frequency signal through the coaxial transmission line and the waveguide.
The said waveguide is a coaxial waveguide converter comprised by the some waveguide part from which the dimension changes in steps from the one end to which the said coaxial transmission line is connected to the other end which is a standard blank tube.
(2) The coaxial waveguide converter according to (1), wherein one end of the coaxial transmission line is connected to the vicinity of the short-circuited surface of the waveguide portion that is a short-circuited surface.
(3) The size of the waveguide portion to which the coaxial transmission line is connected is selected so as to be matched with the coaxial transmission line via a coaxial connector. Tube converter.
(4) The coaxial waveguide converter according to (1), (2) or (3), wherein the waveguide is flat on one side and changes only on the other side in steps.
(5) The coaxial waveguide converter according to (1), (2), or (3), wherein the opposite surfaces of the waveguide are changed stepwise.
(6) In a coaxial waveguide converter for converting a coaxial transmission line into a waveguide and transmitting a high-frequency signal through the coaxial transmission line and the waveguide,
The waveguide includes a first waveguide portion to which the coaxial transmission line is connected, a third waveguide portion having the dimensions of a standard elementary tube, and a second conductor between the first and third waveguide portions. Formed in a step shape by three waveguide portions of different dimensions of the wave tube portion, the characteristic impedance of the first waveguide portion is selected so as to be matched with the coaxial transmission line via a coaxial connector. Coaxial waveguide converter.
(7) The coaxial waveguide converter according to (6), wherein the coaxial transmission line is a coaxial connector provided on a wall surface in the vicinity of the short-circuit surface of the first waveguide portion.

  According to the coaxial waveguide converter of the present invention, the following remarkable effects in practical use can be obtained. That is, since there is no adjustment, productivity is excellent. Further, excellent electrical characteristics can be obtained in an unadjusted state. For example, it is possible to realize a return loss of −20 dB at a specific bandwidth of about 32% and a return loss of −30 dB at a specific bandwidth of 19%.

  Hereinafter, the configuration and operation of a preferred embodiment of a coaxial waveguide converter according to the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the same reference numerals are used for corresponding components for convenience of explanation.

  First, FIG. 1 shows a first embodiment of a coaxial waveguide converter of a first embodiment according to the present invention, in which (A) is a front view and (B) is a longitudinal sectional view. In the coaxial waveguide converter 10 of the first embodiment, for convenience of explanation, the width direction (that is, the lateral direction in FIG. 1A) is the X direction and the height (that is, the longitudinal direction in FIG. 1A). ) In the Y direction and the length (that is, the horizontal direction in FIG. 1B) is the Z direction.

  The coaxial waveguide converter 10 includes a first waveguide portion 11, a second waveguide portion 12, and a third waveguide portion 13 that are sequentially formed in the Z direction. One end of the first waveguide portion 11 (the right end in FIG. 1B) is a short-circuited surface 14, and a flange 15 is provided at one end of the third waveguide portion 13 farthest from the short-circuited surface 14 that is the other end. Is formed. The insides of the first waveguide portion 11 to the third waveguide portion 13 are hollow and form an opening 16. A coaxial connector 21 is attached to the outside of the first waveguide portion 11 in the vicinity of the short-circuit surface 14, and the internal probe 22 of the opening 16 is disposed on the coaxial connector 21.

  Here, the first waveguide portion 11 extends from 0 to Z0 in the Z direction. The second waveguide portion 12 extends from Z0 to Z1 in the Z direction. The third waveguide portion 13 extends from Z1 to Z2 in the Z direction. Here, the first waveguide portion 11 to the third waveguide portion 13 are configured to increase in height sequentially. That is, the second waveguide portion 12 is higher than the first waveguide portion 11 and the third waveguide portion 13 is higher than the second waveguide portion 12. In the coaxial waveguide converter 10 of the first embodiment, the first waveguide portion 11 to the third waveguide portion 13 have a flat upper wall. A stepped portion (step) 17 is formed at the boundary of the second waveguide portion 12, and a stepped portion 18 is formed at the boundary of the second waveguide portion 12 and the third waveguide portion 13. Yes.

  In the coaxial waveguide converter 10 shown in FIG. 1, the dimension of the opening 14 of the first waveguide portion 11, that is, the width (x) and the height (y) are the most without adjustment with the impedance of the coaxial connector 21. It is selected to be consistent. The length (Z direction) of the second waveguide portion 12 that is the intermediate portion can be selected as appropriate, but is about 0.25λg. And the dimension of the 3rd waveguide part 13 is selected to the dimension of the standard blank mentioned above. Here, preferably, the dimension of the first waveguide portion 11 is selected so as to facilitate matching through the coaxial transmission line and the coaxial connector 21. Further, the distance from the short-circuit surface is selected for the coaxial connector 21 so that the first waveguide portion 11 and the coaxial transmission path can be easily matched. Empirically, when the characteristic impedance of the coaxial transmission line is 50 ohms, matching is facilitated by selecting the characteristic impedance of the first waveguide portion to be about 280 ohms.

  Next, the electrical characteristics of the coaxial waveguide converter will be described with reference to FIGS. 2A to 4B, (A) is a characteristic diagram of frequency (horizontal axis: GHz) versus return loss (vertical axis: dB), and (B) is a Smith chart.

  FIG. 2 shows the return loss characteristic when only the waveguide dimensions of the conventional standard blank tube (that is, the whole is the same as the third waveguide portion 13). FIG. 3 shows the return loss characteristic of the first waveguide portion 11. 4 shows the return loss characteristic of the entire coaxial waveguide converter 10 according to the present invention shown in FIG.

  As is clear from the comparison of FIGS. 2 to 4, since sufficient electrical characteristics cannot be obtained with only the standard blank tube, a plurality of adjustment screws are provided at a plurality of locations, and desired characteristics can be obtained by adjusting these adjustment screws. Have gained. As characteristics thereof, the return loss is -20 dB at a specific bandwidth of about 5.4%, and the return loss is about -30 dB at a specific bandwidth of about 1%. On the other hand, in the present invention, in an unadjusted state, a return loss of −20 dB is achieved at a specific bandwidth of about 32%, and a return loss of −30 dB is achieved at a specific bandwidth of about 19%.

  Next, FIG. 5 shows a configuration of a coaxial waveguide converter 10A according to a second embodiment of the present invention, in which (A) is a front view and (B) is a longitudinal sectional view. Also in this coaxial waveguide converter 10A, the first waveguide portion 11, the second waveguide portion 12, and the third waveguide portion 13 are formed in a step shape by three portions having different dimensions. However, the stepped portions 17 and 18 of the coaxial waveguide converter 10A are formed in the + Y direction, whereas the coaxial waveguide converter 10 of the first embodiment described above is in the -Y direction. Is different.

  6A and 6B show the configuration of a coaxial waveguide converter 10B according to a third embodiment of the present invention, in which FIG. 6A is a front view and FIG. 6B is a longitudinal sectional view. This third embodiment differs from the first and second embodiments described above in that stepped portions 17 and 18 are formed on both opposing surfaces in the ± Y direction.

  FIG. 7 shows the configuration of a coaxial waveguide converter 10C of the fourth embodiment according to the present invention. In the fourth embodiment, like the third embodiment shown in FIG. 6, the stepped portions 17 and 18 are formed on both surfaces facing each other in the ± Y direction. The difference is that the dimensions become smaller in the order of the wave tube portion 12 and the third waveguide portion 13.

  Next, FIG. 8 shows a configuration of a coaxial waveguide converter 10D according to a fifth embodiment of the present invention, where (A) is a front view, and (B) and (C) are longitudinal sectional views in different directions. is there. The coaxial waveguide converter 10D of the fifth embodiment is different from the above-described first or second embodiment in that stepped portions 17 and 18 are formed in the +/− X direction.

  FIG. 9 shows a configuration of a coaxial waveguide converter 10E according to the sixth embodiment of the present invention, and (A) to (C) are the same as FIGS. 8 (A) to (C). The coaxial waveguide converter 10E of the sixth embodiment is different from the above-described third embodiment of FIG. 6 in that stepped portions 17 and 18 are formed on both opposing surfaces in the ± X direction.

  Finally, FIG. 10 shows a configuration of a coaxial waveguide converter 10F of the seventh embodiment according to the present invention, and (A) to (C) correspond to FIGS. 9 (A) to (C). The coaxial waveguide converter 10F of the seventh embodiment is the same as the fifth embodiment shown in FIG. 8 in that stepped portions 17 and 18 are formed on one surface in the + X direction. As in the fourth embodiment, the dimensions of the first waveguide portion 11, the second waveguide portion 12, and the third waveguide portion 13 become smaller in this order. The operations and characteristics of the coaxial waveguide converters 10A to 10F of the second to seventh embodiments are the same as those of the coaxial waveguide converter 10 of the first embodiment.

  The configuration and operation of various embodiments of the coaxial waveguide converter according to the present invention have been described above in detail. However, it should be noted that such examples are merely illustrative of the invention and do not limit the invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.

The structure of the coaxial waveguide converter of 1st Example by this invention is shown, (A) is a front view, (B) is a longitudinal cross-sectional view. It is a figure which shows the electrical property of the coaxial waveguide converter of a conventional structure. It is a figure which shows the electrical property of the 1st waveguide part of the coaxial waveguide converter shown in FIG. It is a figure which shows the electrical property of the whole coaxial waveguide converter shown in FIG. It is a figure which shows the structure of the coaxial waveguide converter of 2nd Example of this invention. It is a figure which shows the structure of the coaxial waveguide converter of 3rd Example of this invention. It is a figure which shows the structure of the coaxial waveguide converter of 4th Example of this invention. It is a figure which shows the structure of the coaxial waveguide converter of 5th Example of this invention. It is a figure which shows the structure of the coaxial waveguide converter of 6th Example of this invention. It is a figure which shows the structure of the coaxial waveguide converter of 7th Example of this invention.

Explanation of symbols

10, 10A to 10F Coaxial waveguide converter 11 First waveguide portion 12 Second waveguide portion 13 Third waveguide portion 14 Short-circuit surface 17, 18 Stepped portion (step)
21 Coaxial connector 22 Probe

Claims (7)

In a coaxial waveguide converter that converts a coaxial transmission line into a waveguide and transmits a high-frequency signal through the coaxial transmission line and the waveguide.
The waveguide is composed of a plurality of waveguide portions whose dimensions change stepwise from one end to which the coaxial transmission line is connected to the other end, which is a standard blank tube. converter.   2. The coaxial waveguide converter according to claim 1, wherein the coaxial transmission line is connected in the vicinity of the short-circuited surface of the waveguide portion, one end of which is a short-circuited surface.   The coaxial waveguide according to claim 1 or 2, wherein a dimension of the waveguide portion to which the coaxial transmission line is connected is selected so as to be matched with the coaxial transmission line via a coaxial connector. Wave tube converter.   4. The coaxial waveguide converter according to claim 1, wherein one side of the waveguide is flat and only the other side changes in a stepped manner. 5.   4. The coaxial waveguide converter according to claim 1, wherein the opposite surfaces of the waveguide change in a stepped manner. 5. In a coaxial waveguide converter that converts a coaxial transmission line into a waveguide and transmits a high-frequency signal through the coaxial transmission line and the waveguide.
The waveguide includes a first waveguide portion to which the coaxial transmission line is connected, a third waveguide portion having the dimensions of a standard elementary tube, and a second conductor between the first and third waveguide portions. Formed in a step shape by three waveguide portions of different dimensions of the wave tube portion, the characteristic impedance of the first waveguide portion is selected so as to be matched with the coaxial transmission line via a coaxial connector. A coaxial waveguide converter characterized by the above.   The coaxial waveguide converter according to claim 6, wherein the coaxial transmission line is a coaxial connector provided on a wall surface in the vicinity of a short-circuit surface of the first waveguide portion.

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