JP3976004B2 - T-branch waveguide and array antenna - Google Patents

Description

  The present invention relates to a T-branch waveguide used for power distribution and synthesis in the microwave and millimeter wave bands.

An H-plane T-branch waveguide is used for T-branching at the waveguide H-plane for power distribution and synthesis. The H-plane T-branch waveguide is composed of a main waveguide and a side waveguide having a rectangular cross section coupled to one H-plane of the main waveguide.
Conventionally, in order to change the distribution ratio of an H-plane T-branch waveguide, two-port output terminals are connected by side waveguides having different H-plane heights, and the connection between the main waveguide and the side waveguide is connected. A method of changing the height of the side waveguides before and after is known. In addition, there has been known a method of changing a distribution ratio by installing a conductor post at a position shifted from the center line of the main waveguide (see, for example, Patent Document 1).

JP 2001-85901 A (page 4, FIG. 1)

  However, the former method has a problem that it is difficult to manufacture because a step is generated in the waveguide. Further, in order to return the height of the waveguide to the standard waveguide height, an impedance converter or the like is required, and there is a problem that the configuration becomes complicated.

  On the other hand, in the latter method, the distribution ratio can be easily changed and the structure is easy to manufacture. However, when the main waveguide is an input terminal and the side waveguide is a 2-port output terminal, There was a problem that the passing phase was shifted between the two output terminals.

  The present invention has been made in order to solve the above-described problems. The power can be unequally distributed or unequally synthesized between the main waveguide and the side waveguide. The object of the present invention is to realize an H-plane T-branch waveguide with a small passage phase difference between two terminals in the tube and a uniform height.

The T-branch waveguide according to the present invention has a main waveguide having one end as a first terminal, one end serving as a second terminal, and the other end serving as a third terminal, and has a connection port on one H surface. The other end of the main waveguide is provided with a side waveguide connected to the connection port,
In the vicinity of the connection port, first and second irises having different widths are arranged on opposite H surfaces of the main waveguide, and the side waveguides are arranged at positions shifted from the center line of the main waveguide. A conductor plate is disposed in contact with the upper and lower sides and protruding from the H surface on the side opposite to the H surface on the connection port side in the side waveguide.

  According to the T-branch waveguide according to the present invention, the iris is provided asymmetrically around the connection port with the side waveguide of the main waveguide, and the conductor plate is arranged shifted from the center line of the main waveguide. By doing so, it is possible to unequally distribute or combine electric power between the second terminal and the third terminal with a desired distribution ratio with little loss, and the second and third after distribution or before combination. The passing phases of these terminals can be made substantially equiphase.

Embodiment 1 FIG.
FIGS. 1A and 1B are diagrams illustrating an example of a power feeding circuit of a waveguide slot array antenna. FIG. 1A is a front view and FIG. 1B is a back view.
In the figure, the waveguide slot array antenna includes a radiation waveguide 2 provided with a plurality of radiation slots 1 and a waveguide feeding circuit 4 that feeds the radiation waveguide 2. A plurality of radiation waveguides 2 are arranged in parallel to form a plurality of subarrays 3.

  The radiating waveguide 2 and the waveguide feeding circuit 4 are each provided with an oblique slot 5, and the radiating waveguide 2 and the waveguide feeding circuit 4 are connected to each other through the oblique slots 5. Feeding to each subarray 3 is performed by a waveguide feeding circuit 4, and excitation of the radiation waveguide 2 is performed in an oblique slot 5. The waveguide feeding circuit 4 is constituted by a T-branch waveguide.

  In general, since the number of radiation slots 1 for each sub-array 3 is not constant, the H-plane T-branch needs to be unequal. In addition, even when the number of radiation slots 1 for each subarray 3 is the same, when an aperture distribution such as a tailor distribution is provided, the T-branch waveguide on the H plane needs to be unequally distributed. In the example of FIGS. 1A and 1B, the H-plane T-branch waveguide indicated by the broken line 7 is equally distributed, but the H-plane T-branch waveguide indicated by the broken line 6 is unequally distributed. It becomes.

FIG. 2 shows an unequal distribution type H-plane T-branch waveguide according to the first embodiment of the present invention. 2A is a perspective view, and FIG. 2B is a cross-sectional view taken along a plane horizontal to the E plane.
In the figure, it is composed of a main waveguide 11 and a side waveguide 12 having a rectangular cross section coupled to one H-plane of the main waveguide 11. The main waveguide 11 has a first terminal 8 at one end and a connection terminal 20 at the other end. The side waveguide 12 has one end as a second terminal 9 and the other end as a third terminal 10, and a connection port is provided on one H surface. The connection terminal 20 of the main waveguide 11 is connected to the connection port 21 of the side waveguide 12. At this time, the main waveguide 11 and the side waveguide 12 are connected so that their central axes are orthogonal. The main waveguide 11 and the side waveguide 12 have the same H-plane height.

  Around the connection port 21 of the side waveguide 12, an iris 16 (first iris) and an iris 17 (second iris) are provided. The iris 16 is provided so as to protrude from one H surface of the main waveguide 11 into the waveguide on the second terminal side of the side waveguide 12. The iris 17 is provided so as to protrude into the waveguide from the other H surface of the main waveguide 11 on the third terminal side of the side waveguide 12. That is, the irises 16 and 17 are arranged on the opposite H surfaces of the main waveguide 11 so as to face each other. The widths of the irises 16 and 17 protruding from the H surface of the main waveguide 11 are different from each other. In the example shown in FIG. 2, the iris 17 has a larger width protruding into the waveguide than the iris 16.

  A conductor plate 18 is provided in contact with the upper and lower sides of the side waveguide 12 and protruding from the H surface on the side opposite to the H surface on the connection port 21 side in the side waveguide 12. The conductor plate 18 is disposed at a position shifted from the center line 15 of the main waveguide 11 to the third output terminal 10 side.

Next, the operation will be described.
The millimeter wave or microwave band RF signal input from the first terminal 8 is distributed to the second terminal 9 and the third terminal 10 and output. Here, in the T-branch waveguide shown in FIG. 2, the iris 17 on the third terminal 10 side is set to an appropriate size, and the iris 16 on the second terminal 9 side is set on the third terminal 10 side. It is made shorter than the iris 17 by an appropriate size. This strengthens the signal on the second terminal 9 side and weakens the signal on the third terminal 10 side. Furthermore, by arranging the conductor plate 18 at a position shifted from the center line 15 of the main waveguide 11 on the third terminal 10 side by an appropriate distance, substantially equiphase characteristics can be obtained.

FIG. 3A shows an example of an amplitude frequency characteristic of a signal distributed from the first terminal 8 to the second terminal 9 and the third terminal 10. In the figure, the horizontal axis represents frequency, the vertical axis represents signal amplitude [dB], the amplitude of the second terminal 9 is port 2, and the amplitude of the third terminal 10 is port 3.
In an ideal equal distribution, the signals of the second terminal 9 and the third terminal 10 are both -3 dB. However, in the T-branch waveguide according to the first embodiment, the signal at the second terminal 9 is large (−2 [dB]) and the signal at the third terminal 10 is small (−5 [dB]). It can be seen that unequal distribution characteristics are obtained.

Next, FIG. 3B shows the phase characteristics of the passing signals distributed from the first terminal 8 to the second terminal 9 and the third terminal 10, respectively. In the figure, the vertical axis represents the frequency, and the horizontal axis represents the passing phase difference (S ₃₁ / S ₂₁ ). Here, in order to explain the effect of the phase characteristic of the T-branch waveguide according to this embodiment, the phase characteristic of the conventional T-branch waveguide is shown by a broken line in the drawing as a comparative reference. As shown in the figure, the T-branch waveguide of the conventional example has a phase difference of about 50 °, whereas the T-branch waveguide of this embodiment has almost equal phase characteristics. Yes.

  FIG. 4 shows a configuration of a conventional T-branch waveguide exemplified as a comparative control in FIG. 4A is a perspective view, and FIG. 4B is a cross-sectional view on the E plane. In the conventional example shown in FIG. 4, a conductor post 14 is provided in the side waveguide 12 on the third terminal 10 side of the center line 15 of the main waveguide. Instead, the irises 16 and 17 and the conductor plate 18 are not installed. In the figure, the same reference numerals as those in FIG. 2 are the same as those in FIG.

  As described above, in the T-branch waveguide according to this embodiment, the iris is provided asymmetrically in the left-right asymmetry around the connection port with the side waveguide of the main waveguide, and the conductor plate is disposed on the center line of the main waveguide. By disposing them, the power can be distributed unevenly between the second terminal 9 and the third terminal 10 at a desired distribution ratio with little loss, and the second terminal 9 after distribution is distributed. And the passing phase of the third terminal 10 can be made substantially equal.

  In the above description, an example in which a T-branch waveguide is used as an unequal distributor for input signals has been described. However, a T-branch waveguide may be used as a synthesizer for unequal synthesis. In this case, needless to say, RF signals having different power amplitudes input to the second terminal 9 and the third terminal 10 are combined and output to the first terminal 8. At this time, the power can be unequally synthesized with a desired distribution ratio between the second terminal and the third terminal with little loss, and the passing phases of the second and third terminals before the synthesis can be determined. The phase can be almost equal.

Embodiment 2. FIG.
FIG. 5 is a diagram showing the configuration of the second embodiment of the present invention. FIG. 5A is a perspective view, and FIG. 5B is a cross-sectional view at the E plane. As shown in the figure, in this embodiment, a T-branch waveguide is configured without providing the iris 16 on the second terminal 9 side. Even with such a configuration, the same effect can be obtained by appropriately setting the width of the iris 17 protruding into the waveguide.
In the figure, the same reference numerals as those in FIG. 2 denote the same elements as those in FIG.

It is a figure which shows the structure of the waveguide slot array antenna by Embodiment 1 of this invention. It is a figure which shows the structure of the T branch waveguide by Embodiment 1 of this invention. It is a figure which shows the amplitude characteristic of (a) T branching waveguide, and (b) passage phase characteristic by Embodiment 1 of this invention. It is a figure which shows the structure of the conventional T branch waveguide shown as a comparative example. It is a figure which shows other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Radiation slot, 2 Radiation waveguide, 3 Subarray, 4 Waveguide feeding circuit, 5 Diagonal slot, 8 1st terminal, 9 2nd terminal, 10 3rd terminal, 11 Main waveguide, 12 Side conduction Wave tube, 14 conductor post, 15 main waveguide centerline, 16 iris, 17 iris, 18 conductor plate.

Claims (3)

A main waveguide having one end as a first terminal;
One end is a second terminal, the other end is a third terminal, and a side waveguide having a connection port on one H surface and the other end of the main waveguide connected to the connection port,
In the vicinity of the connection port, a first iris is disposed on the second terminal side on the H surface facing the main waveguide, a second iris is disposed on the third terminal side, and the first The iris of 2 is wider than the first iris,
With respect to the center line of the main waveguide , at a position shifted to the third terminal side, it is in contact with the upper and lower sides of the side waveguide and is opposite to the H surface on the connection port side in the side waveguide. A T-branch waveguide characterized in that a conductor plate is disposed so as to protrude from the H-plane. A main waveguide having one end as a first terminal;
One end is a second terminal, the other end is a third terminal, and a side waveguide having a connection port on one H surface and the other end of the main waveguide connected to the connection port,
Around the connection port, an iris is disposed on the third terminal side of the H surface facing the main waveguide,
With respect to the center line of the main waveguide, at a position shifted to the third terminal side, it is in contact with the upper and lower sides of the side waveguide and is opposite to the H surface on the connection port side in the side waveguide. A T-branch waveguide characterized in that a conductor plate is disposed so as to protrude from the H-plane.   An array antenna comprising the T-branch waveguide according to claim 1 or 2 and a plurality of subarrays fed by the T-branch waveguide.

Images