JP5377070B2 - Waveguide / microstrip line converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waveguide/microstrip line converter in a compact configuration, in which an end of a rectangular waveguide to be connected is prevented from projecting in the width direction of a microstrip line as much as possible. <P>SOLUTION: A ground conductor pattern 2 of a dielectric substrate 1 to which an open end of an end part of the rectangular waveguide 7 is connected is provided with a rough rectangular coupling slot 6 going along a longitudinal side of the open end of the end part, three sides in all obtained by excluding one of two confronting short sides of an external circumference of a rectangular wide conductor pattern 4 similar to the open end of the end part of the rectangular waveguide 7 are connected to the ground conductor pattern 2 by via holes 5 for connection to form a dielectric waveguide, and a strip conductor pattern 3 forming a microstrip line is pulled out from the one short side of the wide conductor pattern 4 in parallel with the longitudinal sides of the wide conductor pattern 4. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a waveguide / microstrip line converter for connecting a rectangular waveguide and a microstrip line.

  As a waveguide / microstrip line converter used in a high frequency band such as a microwave band or a millimeter wave band, for example, in Patent Document 1, the position of a coupling hole is formed on a ground conductor pattern covering one whole surface of a dielectric substrate. The end opening end of the rectangular waveguide is connected to the other surface of the dielectric substrate in a region corresponding to the connection position of the rectangular waveguide. A wide conductor pattern having a closed shape is formed, and a strip conductor pattern constituting a microstrip line is drawn out from one side of the wide conductor pattern in a region not corresponding to the connection position of the rectangular waveguide. Yes.

  In the waveguide / microstrip line converter disclosed in Patent Document 1, in order to make the extending direction of the microstrip line coincide with the electric field direction of the rectangular waveguide, the strip conductor pattern is formed on the rectangular waveguide. It is configured to be pulled out in a direction perpendicular to the wide wall surface.

  By the way, an array antenna that uses a microstrip line as a feed path has a configuration in which microstrip lines to which a large number of antenna elements are attached are juxtaposed on a plane. When a waveguide / microstrip line converter is used for the feeding portion of the array antenna, a rectangular waveguide is disposed for each microstrip line.

  On the other hand, the grading lobe that becomes a problem in the directivity pattern of the array antenna becomes smaller as the array interval becomes narrower, and it is said that the array interval that can be completely suppressed needs to be ½ wavelength or less. The array interval in this case is the arrangement interval of the microstrip lines, that is, the arrangement interval of the rectangular waveguides.

JP2003-273612A (FIG. 1)

  Then, when the conventional waveguide / microstrip line converter is used in the feeding portion of the array antenna, the interval between the microstrip lines, which is the array interval, is the interval defined by the wide wall dimension of the rectangular waveguide. Therefore, the wavelength becomes approximately 0.9 wavelength far from the interval at which the grading lobe can be suppressed, and there is a problem that the generation of the grading lobe cannot be avoided and the beam scanning range is limited.

  The present invention has been made in view of the above, and a waveguide / microstrip line converter having a compact configuration capable of minimizing the end of a connected rectangular waveguide from protruding in the width direction of the microstrip line. The purpose is to obtain.

  In order to achieve the above-mentioned object, a waveguide / microstrip line converter according to the present invention includes an end portion of a rectangular waveguide connected to a ground conductor pattern covering one whole surface of a dielectric substrate. A substantially rectangular coupling slot is provided along the longitudinal side of the opening end, and the end opening end of the rectangular waveguide is connected to the other surface of the dielectric substrate according to the position where the coupling slot is formed. In the region corresponding to the connection position, a rectangular wide conductor pattern substantially similar to the shape of the end opening end is formed, and in the region not corresponding to the connection position of the end opening end of the rectangular waveguide, the strip conductor is formed. A pattern is formed by being drawn out in parallel with two opposing long sides of the wide conductor pattern from the center of one of two opposing short sides of the wide conductor pattern. At least three sides excluding the vicinity where the strip conductor pattern is drawn out are connected to the ground conductor pattern using a connecting conductor, and the coupling slot is formed by connecting the two long sides from the line in the drawing direction of the strip conductor pattern. It is characterized by being formed in parallel with the two long sides in a state offset to one side.

  According to the present invention, since the strip conductor pattern constituting the microstrip line is drawn out in the direction parallel to the wide wall of the rectangular waveguide, the end of the connected rectangular waveguide is in the width direction of the microstrip line. There is an effect that the amount of protrusion can be made as small as possible.

FIG. 1 is a perspective view showing an external configuration of a waveguide / microstrip line converter according to an embodiment of the present invention. FIG. 2 is a sectional view showing the internal configuration of the waveguide / microstrip line converter shown in FIG. FIG. 3 is a plan view showing the formation surface of the strip conductor pattern and the wide conductor pattern of the dielectric substrate in the waveguide / microstrip line converter shown in FIG. FIG. 4 is a plan view showing a ground conductor pattern forming surface of a dielectric substrate in the waveguide / microstrip line converter shown in FIG. FIG. 5 is a plan view showing a configuration example of an array antenna using a conventional waveguide / microstrip line converter as a feeding portion. FIG. 6 is a plan view showing a configuration example of an array antenna using the waveguide / microstrip line converter shown in FIG.

  Embodiments of a waveguide / microstrip line converter according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a perspective view showing an external configuration of a waveguide / microstrip line converter according to an embodiment of the present invention. FIG. 2 is a sectional view showing the internal configuration of the waveguide / microstrip line converter shown in FIG. FIG. 3 is a plan view showing a strip conductor pattern and a wide conductor pattern forming surface of a dielectric substrate in the waveguide / microstrip line converter shown in FIG. FIG. 4 is a plan view showing a ground conductor pattern forming surface of a dielectric substrate in the waveguide / microstrip line converter shown in FIG. 2 is a cross-sectional view taken along line A-A ′ shown in FIGS. 3 and 4.

  In FIG. 1 and FIG. 2, the dielectric substrate 1 has a rectangular shape for easy understanding. A ground conductor pattern 2 is formed on the entire surface of one surface (lower surface in the illustrated example) of the dielectric substrate 1. Further, on the other surface (upper surface in the illustrated example) of the dielectric substrate 1, a strip conductor pattern 3 is formed on one end side in the longitudinal direction of the dielectric substrate 1, and a wide rectangular shape is formed on the other end side in the longitudinal direction. A conductor pattern 4 is formed. In the illustrated example, the short side of the dielectric substrate 1 and the short side of the wide conductor pattern 4 are assumed to have the same length.

  The strip conductor pattern 3 is formed along the longitudinal direction of the wide conductor pattern 4 so as to be drawn out from one of two opposing short sides of the wide conductor pattern 4. That is, a microstrip line including the strip conductor pattern 3, the ground conductor pattern 2, and the dielectric substrate 1 is formed along the longitudinal direction of the dielectric substrate 1 on one end side in the longitudinal direction of the dielectric substrate 1. Has been.

  In addition, the wide conductor pattern 4 has a large number of connecting three sides (two long sides facing the other short side) excluding one short side from which the strip conductor pattern 3 is drawn out of the outer periphery. The via conductor 5 is connected to the ground conductor pattern 2. The connection via 5 is filled with, for example, a conductive agent so as to form a conductor wall (via wall).

  That is, on the other end side in the longitudinal direction of the dielectric substrate 1, a dielectric waveguide composed of the wide conductor pattern 4, the via wall by the connection via 5 and the ground conductor pattern 2 is formed. In this dielectric waveguide, the other short side of the wide conductor pattern 4 is short-circuited by the via wall, and one short side of the wide conductor pattern 4 is opened. The microstrip line is drawn from the open end.

  Then, on the side of the ground conductor pattern 2 facing the wide conductor pattern 4, a substantially rectangular coupling slot 6 is formed along the longitudinal direction of the wide conductor pattern 4 under the conditions described later. The length of the coupling slot 6 is about ½ wavelength. The rectangular waveguide 7 is connected to the ground conductor pattern 2 in such a manner that the longitudinal side of the open end of the rectangular waveguide 7 is aligned in parallel with the longitudinal direction of the coupling slot 6.

  In the illustrated example, the size of the wide conductor pattern 4 is shown larger than the opening shape of the rectangular waveguide 7 to be connected. However, since the size of the wide conductor pattern 4 depends on the dielectric constant of the dielectric substrate 1, it may be smaller than the opening shape of the rectangular waveguide 7. That is, the size of the wide conductor pattern 4 is generally similar to the opening shape of the rectangular waveguide 7.

  Here, as shown in FIG. 3, the strip conductor pattern 3 is formed from one short side of the wide conductor pattern 4 on the line AA ′ passing through the center of two opposite short sides of the wide conductor pattern 4. Has been pulled out.

  Further, as shown in FIG. 4, the coupling slot 6 is offset to one side of the two opposing long sides of the wide conductor pattern 4 with respect to the AA ′ line that is the drawing direction of the strip conductor pattern 3. , Formed in parallel with the two long sides.

  In short, the strip conductor pattern 3, the coupling slot 6, and the rectangular waveguide 7 are respectively parallel to the direction in which the strip conductor pattern 3 is drawn, the long side of the coupling slot 6, and the wide wall of the rectangular waveguide 7. Are arranged as follows.

  2 will be described with reference to the dielectric waveguide formed as described above. FIG. 2 shows the waveguide / macrostrip line converter shown in FIG. The cross section taken along the line is shown, but the line AA ′ shown in FIGS. 3 and 4 is parallel to the center line (so-called tube axis) of the dielectric waveguide. Therefore, the strip conductor pattern 3 is drawn out along the center line of the dielectric waveguide, and the coupling slot 6 is formed at a position offset from the center line of the dielectric waveguide. The rectangular waveguide 7 to be connected is arranged with its wide wall parallel to the center line of the dielectric waveguide.

  Next, the operation will be described. The coupling slot 6 is arranged in such a direction as to cut off the current flowing in the end opening end of the rectangular waveguide 7. Therefore, a magnetic current is generated in the coupling slot 6 by the electromagnetic wave propagating through the rectangular waveguide 7. The coupling slot 6 is disposed at a position offset from the center line of the dielectric waveguide. Therefore, the fundamental wave electromagnetic wave is excited in the dielectric waveguide by the magnetic current generated in the coupling slot 6. Thus, since the rectangular waveguide 7 and the dielectric waveguide are coupled via the magnetic current, it is not necessary to match the directions of the electric fields as in the conventional example.

  The dielectric waveguide is short-circuited at one end in the longitudinal direction by a via wall formed by the connection via 5. Therefore, the fundamental mode electromagnetic wave excited in the dielectric waveguide travels in the direction of the strip conductor pattern 3 connected to the other end in the longitudinal direction. Since the electric field distribution of the fundamental mode electromagnetic wave excited in the dielectric waveguide is close to the electric field distribution of the microstrip line, it can propagate through the microstrip line without causing large reflection.

  As described above, even when the microstrip line is drawn out in the direction parallel to the wide wall of the rectangular waveguide, the rectangular waveguide and the microstrip line can be connected without causing large reflection.

  Next, a case where a waveguide / microstrip line converter is used for the feeding portion of the array antenna will be described with reference to FIGS. FIG. 5 is a plan view showing a configuration example of an array antenna using a conventional waveguide / microstrip line converter as a feeding portion. FIG. 6 is a plan view showing a configuration example of an array antenna using the waveguide / microstrip line converter shown in FIG.

  An array antenna that uses a microstrip line as a feed path has a configuration in which microstrip lines having a large number of antenna elements are arranged adjacent to each other on a printed wiring board. 5 and 6 show a case where four microstrip lines are arranged adjacent to each other. For convenience of explanation, the strip conductor pattern code is used as the microstrip line code.

  As shown in FIG. 5, in the conventional waveguide / microstrip line converter, since the extending direction of the microstrip line 21 matches the electric field direction of the rectangular waveguide, the microstrip line 21 has a wide width. The conductor pattern 20 is drawn in a direction orthogonal to the longitudinal side of the conductor pattern 20, that is, a direction orthogonal to the wide wall of the rectangular waveguide. For this reason, in an array antenna in which a microstrip line 21 having a large number of antenna elements 22 attached to a printed wiring board is placed adjacent to each other, the arrangement interval of the microstrip lines 21 is an interval defined by the wide wall size of the rectangular waveguide. Therefore, the array interval cannot be narrower than about 0.9 wavelength. Therefore, conventionally, the generation of grading lobes is unavoidable, and the beam scanning range is limited.

  In contrast, in the waveguide / microstrip line converter according to the present embodiment, the strip conductor pattern 3 is parallel to the long side of the wide conductor pattern 4, that is, parallel to the wide wall of the rectangular waveguide. I tried to pull it out in the direction to do. Therefore, in an array antenna in which strip conductor patterns 3 each having a large number of antenna elements 10 attached to a printed wiring board are arranged adjacent to each other, the spacing between the strip conductor patterns 3 is an interval defined by the wide wall size of the rectangular waveguide. Narrow to: Specifically, the array interval can be narrowed to about 0.6 wavelength, which is close to the interval of about 0.5 wavelength necessary for suppressing grading lobes. As a result, it is possible to suppress the grating lobe, which has been difficult in the past, and to expand the beam scanning range.

  As described above, according to the present embodiment, since the microstrip line is drawn out in the direction parallel to the wide wall of the rectangular waveguide, the end of the rectangular waveguide to be connected is the width of the microstrip line. Projecting in the direction can be made as small as possible. Therefore, a waveguide / microstrip line converter is obtained that allows the array interval to be narrowed to such an extent that the grating lobe can be suppressed when used in the feeding portion of the array antenna.

  As described above, the waveguide / microstrip line converter according to the present invention has a compact configuration in which the end of the connected rectangular waveguide can be minimized as much as possible in the width direction of the microstrip line. It is useful as a microstrip line converter, and is particularly suitable for use in a feeding portion of an array antenna to narrow the array interval to such an extent that grating lobes can be suppressed.

1 Dielectric Substrate 2 Ground Conductor Pattern 3 Strip Conductor Pattern 4 Wide Conductor Pattern 5 Connecting Via 6 Coupling Slot 7 Rectangular Waveguide

Claims (1)

A ground conductor pattern that covers the entire surface of one side of the dielectric substrate is provided with a generally rectangular coupling slot along the long side of the open end of the connected rectangular waveguide;
On the other surface of the dielectric substrate,
In a region corresponding to the connection position of the end opening end of the rectangular waveguide connected in accordance with the formation position of the coupling slot, a rectangular wide conductor pattern substantially similar to the shape of the end opening end is formed. In the region not corresponding to the connection position of the end opening end of the rectangular waveguide, the strip conductor pattern is opposed to the wide conductor pattern 2 from the center of one of the two short sides opposed to the wide conductor pattern. Formed in parallel with one long side,
The wide conductor pattern is connected to the ground conductor pattern using a connection conductor on at least three sides excluding the vicinity where the strip conductor pattern is drawn out of the outer periphery,
The long side of the coupling slot, the direction in which the strip conductor pattern is drawn out, and the wide wall of the rectangular waveguide are arranged in parallel, and the coupling slot is formed between the two long sides of the wide conductor pattern. A waveguide / microstrip line converter characterized by being offset from the center line to one side .

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