JP2015097337A - Distribution circuit and array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distribution circuit which reduces influences to be exerted upon a distribution property and is capable of reducing a reflection loss in a predetermined frequency.SOLUTION: The distribution circuit includes: a main waveguide 2 of which one end side is defined as a first port P1 and another end side is defined as a second port P2; and a branched waveguide 3 in which a first branched waveguide 5 and a second branched waveguide 6 are formed side by side in parallel of which one end is connected while opposing a slit 4 formed on a side surface 2a of the main waveguide 2 and another end side is defined as a third port P3 and a fourth port P4. Inside of the main waveguide 2, a first post 8 and a second post 9 are disposed side by side along a side surface 2b at an opposite side of the side surface 2a where the slit 4 is formed. The first post 8 is provided while protruding from a position opposing the slit 4 toward the inside of the main waveguide 2 by a first protruding amount T1. The second post 9 is provided while being positioned closer to the first port P1 than the first post 8 and protruding toward the inside of the main waveguide 2 by a second protruding amount T2 smaller than the first protruding amount T1.

Description

  The present invention relates to a distribution circuit and an array antenna.

  The radio wave in the microwave band or the millimeter wave band is an electromagnetic wave (electromagnetic field) having a wavelength of 1 m to 100 μm and a frequency of 300 MHz to 3 THz. Radio waves in the microwave band or millimeter wave band are applied in a wide range of fields such as satellite television broadcasting, microwave communication, and radar. For example, quasi-millimeter wave to millimeter wave radio waves having a frequency of several tens of GHz or more are used in the aerospace field. In the millimeter wave band having a frequency of 60 GHz, attention is focused on application to the large-capacity high-speed wireless communication field. In the millimeter wave band with a frequency of 77 GHz, practical application of automobile collision prevention radar has begun.

  In a communication module using radio waves in the microwave band or millimeter wave band, a distribution circuit mainly including a waveguide is often used. This technique is very important particularly in an array antenna that needs to feed many antenna elements.

  An example of a distribution circuit using a waveguide is a distribution circuit 100 shown in FIG. The distribution circuit 100 shown in FIG. 13 is called a π-branch (Pi-Junctions). The main waveguide 101 has one end side as a first port P1 ′ and the other end side as a second port P2 ′. And a first branching waveguide 103 having one end connected to the slit 102 formed on one side surface of the main waveguide 101 and the other end being a third port P3 ′ and a fourth port P4 ′. The second branching waveguide 104 includes a branching waveguide 106 formed in parallel with the partition wall 105 interposed therebetween. A post 107 is provided inside the main waveguide 101.

  In the distribution circuit 100 shown in FIG. 13, when power (a microwave band or a millimeter wave band electromagnetic field) is input from the first port P1 ′, a necessary amount of power is supplied to the third port P3 ′ and the third port P3 ′. After being distributed to the four ports P4 ′, the remaining power is output from the second port P2 ′. Further, the power output from the third port P3 'and the fourth port P4' is required to have the same phase and the same amplitude.

“Waveguide π-Junction with an Inductive Post”, IEICE TRANS.ELECTRON., VOL.E75-C, NO.3 MARCH 1992, Jiro HIROKAWA, Makoto ANDO and Naohisa GOTO

  However, in the conventional distribution circuit 100 shown in FIG. 13 described above, there is a problem that the control method of the design center frequency is unknown and a guideline for frequency characteristic control cannot be found. Specifically, among the design parameters of the distribution circuit 100, the distance “d” from the center of the slit 102 to the center of the partition wall 105 shown in FIG. 14 and the distance “from the center of the slit 102 to the center of the post 107” When the dimension such as “q” is changed, there is a problem that the frequency characteristics of other parameters such as phase balance and amplitude balance are greatly affected in addition to the center frequency at which the reflection coefficient to be controlled becomes the minimum.

  Here, the result of calculating the reflection coefficient [dB] with respect to the change of the frequency [GHz] when “d” is set to three levels W1, W2, and W3 (W1 <W2 <W3) in 100 μm increments is shown in FIG. FIG. 16 shows the result of calculating the amplitude balance characteristic [dB] by simulation, and FIG. 17 shows the result of calculating the phase balance characteristic [dB] by simulation.

  As for the positions of the three levels W1, W2, and W3, as shown in FIG. 18, the position along the center line L1 ′ of the branching waveguide 106 is the origin (0), and the longitudinal direction of the main waveguide 101 ( In the X ′ direction), the first port P1 side is set to the + direction. Then, the calculation by simulation was performed by setting the position of the partition wall 105 to 3 levels W1 = + 0.1, W2 = 0, and W3 = −0.1 in 100 μm (0.1 mm) increments. In this example, the calculation was performed assuming that the design frequency was 60 GHz and the size of the waveguide corresponding to this was assumed.

  As shown in FIGS. 15 to 17, at the level of W1, the design center frequency is controlled to a frequency higher than 60 GHz, and the amplitude balance characteristic is excellent. However, it can be said that the phase balance characteristic is poor. Further, it can be seen that the characteristics fluctuate greatly only by adjusting “d” in increments of 100 μm.

  Specifically, the frequency at which the reflection loss (reflection coefficient) becomes minimum is approximately 55 GHz at the W1 level, approximately 60 GHz at the W2 level, and approximately 65 GHz at the W3 level. Therefore, if the position of “d” is changed in increments of 100 μm, the frequency at which the reflection loss becomes the minimum changes by 5 GHz, and it can be said that the sensitivity is high.

  In addition, when the W2 level is changed to the W3 level, the frequency at which the reflection loss becomes the minimum can be controlled from 60 GHz to 65 GHz, but the phase balance deteriorates at the same time. Further, when the W2 level is changed to the W1 level, the frequency at which the reflection loss becomes the minimum can be controlled from 60 GHz to 65 GHz, but the amplitude balance is simultaneously deteriorated.

  Therefore, “d” has a problem that it has a large influence (high sensitivity) on the characteristics of the distribution circuit 100 other than the frequency characteristics to be controlled as a control parameter. In addition, when controlling design parameters such as “d” and “q” in the vicinity of the connection portion between the main waveguide 101 and the branch waveguide 106, the first branch waveguide 104 and the second branch guide are formed from the slit 102. The influence on the power (electromagnetic field) distributed to the waveguide 105 is large. As a result, it is considered that the distribution characteristics (phase balance and amplitude balance) are adversely affected.

  One aspect of the present invention has been proposed in view of such conventional circumstances, a distribution circuit that has a small influence on distribution characteristics and can reduce reflection loss at a predetermined frequency, and such a distribution circuit. An object of the present invention is to provide an array antenna including

  In order to achieve the above object, a distribution circuit according to an aspect of the present invention includes a main waveguide having one end as a first port and the other end as a second port, and a side surface of the main waveguide. A branch in which a first branching waveguide and a second branching waveguide are formed in parallel with one end connected to the formed slit and the other end side as a third port and a fourth port. A waveguide. Inside the main waveguide, a first post and a second post are arranged side by side along the side surface opposite to the side surface on which the slit is formed. The first post is provided so as to protrude from the position facing the slit toward the inside of the main waveguide by the first protrusion amount. The second post is located closer to the first port than the first post, and is provided so as to protrude toward the inside of the main waveguide with a second protrusion amount smaller than the first protrusion amount. Yes.

  In addition, the second post may be disposed at or near a position along an extension of a corner where one end of the branching waveguide is connected to the main waveguide.

  Moreover, the 1st post and / or the 2nd post may be comprised from the wall.

  Further, the first post and / or the second post may be composed of at least one or a plurality of pillars.

  Further, the first post may be provided so as to be biased toward the second port side with respect to the center line of the branching waveguide.

  Further, the main waveguide and the branching waveguide may be composed of post wall waveguides.

  An array antenna according to an aspect of the present invention includes any one of the distribution circuits.

  As described above, according to one aspect of the present invention, there is provided a distribution circuit that has a small influence on distribution characteristics and can reduce reflection loss at a predetermined frequency, and an array antenna including such a distribution circuit. Is possible.

It is a see-through | perspective perspective view which shows schematic structure of the distribution circuit which concerns on one Embodiment of this invention. FIG. 1 is a cross-sectional view showing a schematic configuration of a distribution circuit. It is a schematic diagram which shows the intensity distribution of the electric field transmitted inside the distribution circuit shown in FIG. It is sectional drawing which shows the modification of a 2nd post. It is sectional drawing which shows the modification of a 2nd post. It is sectional drawing which shows the modification of a distribution circuit. It is a disassembled perspective view which shows schematic structure of the array antenna which concerns on one Embodiment of this invention. It is a graph which shows the result of having calculated by simulation the change of the frequency characteristic of reflection loss when the position of the 2nd post is changed. It is a graph which shows the result of having calculated the change of the frequency characteristic of the amplitude balance when changing the position of the 2nd post by simulation. It is a graph which shows the result of having calculated the change of the frequency characteristic of the phase balance when changing the position of the 2nd post by simulation. It is sectional drawing which shows the dimension of each part of the distribution circuit in an Example. It is sectional drawing for demonstrating the position of the 2nd post in an Example. It is a see-through | perspective perspective view which shows schematic structure of the conventional distribution circuit. It is principal part sectional drawing for demonstrating the design parameter of the distribution circuit shown in FIG. It is a graph which shows the result of having calculated by simulation the change of the frequency characteristic of reflection loss when d shown in FIG. 14 is changed. It is a graph which shows the result of having calculated by simulation the change of the frequency characteristic of an amplitude balance when changing d shown in FIG. It is a graph which shows the result of having calculated by simulation the change of the frequency characteristic of a phase balance when d shown in FIG. 14 is changed. It is sectional drawing for demonstrating the 3 level position of d shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all of the following drawings, in order to make each component easy to see, the scale of the size may be changed depending on the component.

(Distribution circuit)
First, a distribution circuit 1 shown in FIGS. 1 and 2 will be described as an embodiment of the present invention.
FIG. 1 is a perspective view showing a schematic configuration of the distribution circuit 1. FIG. 2 is a cross-sectional view illustrating a schematic configuration of the distribution circuit 1.

  As shown in FIG. 1, the distribution circuit 1 includes a main waveguide 2 and a branch waveguide 3. The main waveguide 2 forms a rectangular cylindrical waveguide, and has one end side as a first port P1 and the other end side as a second port P1. A slit 4 is formed on one side surface 2 a of the main waveguide 2. The slit 4 is a waveguide window in which a central portion of one side surface 2a of the branching waveguide 3 is opened with a predetermined width.

  The branching waveguide 3 forms a rectangular cylindrical waveguide, and is connected to one side surface 2 a of the main waveguide 2 with one end thereof facing the slit 4. The branching waveguide 3 forms a first branching waveguide 5 and a second branching waveguide 6 having the other end side as a third port P3 and a fourth port P4. The first branching waveguide 5 and the second branching waveguide 6 are formed in parallel to each other with a partition wall 7 partitioning the inside of the branching waveguide 3 interposed therebetween. The partition wall 7 is disposed along the center line L1 of the branching waveguide 3. In addition, one end of the partition wall 7 is disposed away from the slit 4 by a predetermined distance.

  Inside the main waveguide 2, a first post 8 and a second post 9 are arranged side by side along a side surface 2 b opposite to the side surface 2 a where the slit 4 is formed. The first post 8 is constituted by a wall 8a. The wall 8a is provided so as to protrude from the position facing the slit 4 toward the inside of the main waveguide 2 by the first protrusion amount T1. Further, the first post 8 (the plurality of poles 8a) is provided by being deviated by a predetermined distance (referred to as a deviation amount) S on the second port P2 side from the center line L1 of the branching waveguide 3. Yes.

  For the first protrusion amount T1 and the deviation amount S of the first post 8, the power input from the first port P1 described later is used as the third port P3, the fourth port P4, and the second port. It is possible to adjust appropriately according to the proportion distributed to P4.

  The second post 9 is composed of a single pole 9a. The pole 9a is located closer to the first port P1 than the first post 8 and protrudes toward the inside of the main waveguide 2 with a second protrusion amount T2 smaller than the first protrusion amount T1. Is provided. The second post 9 (pole 9 a) is disposed at or near the position along the extension line L 2 of the corner C where one end of the branching waveguide 3 is connected to the main waveguide 2.

  In addition, the position along the extension line of a corner said here means the position along the extension line of the corner including the thickness of the branched waveguide 3 having one end connected to the main waveguide 2. Therefore, in FIG. 2, the position of the second post 9 is defined with reference to the extension line L <b> 2 of the corner C based on the outer contour line of the main waveguide 2 and the branch waveguide 3. The position of the second post 9 may be defined on the basis of the extension line L2 ′ of the corner C ′ based on the inner contour lines of the main waveguide 2 and the branch waveguide 3. Further, at least a part of the second post 9 may be positioned on the extension lines L2 and L2 '. Furthermore, the vicinity mentioned here means that the position of the second post 9 may be deviated from the position along the extension lines L2 and L2 'within a range in which the effects of the present invention described later can be obtained.

  In the distribution circuit 1 having the above-described configuration, as shown in FIG. 3, when power (a microwave band or a millimeter wave band electromagnetic field) is input from the first port P1, a necessary amount of power is obtained. Is distributed to the third port P3 and the fourth port P4, the remaining power is output from the second port P2. Moreover, the electric power output from the third port P3 and the fourth port P4 has the same phase and the same amplitude. FIG. 3 is a schematic diagram showing the intensity distribution of the electric field transmitted inside the distribution circuit 1.

  In the distribution circuit 1 of the present embodiment, the frequency characteristic can be controlled while reducing the influence on the distribution characteristic by adjusting the position of the second post 9. For example, in the longitudinal direction of the main waveguide 2 (X direction in FIG. 3), the second post 9 is positioned on the first port P1 side (−X direction), thereby adjusting to the low frequency side. By positioning the second post 9 on the second port P2 side (+ X direction), the high frequency side can be adjusted.

In addition, this invention is not necessarily limited to the thing of the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the first post 8 and the second post 9 are not limited to those configured by the one wall 8a and the pole 9a described above, but, for example, a plurality of poles 8b, A configuration in which 9b is connected and a plurality of poles 8c and 9c as shown in FIG. Further, the second post 9 is not limited to the pole 9a described above, and may be a wall 9d as shown in FIG. Further, the first post 8 and the second post 9 are configured to be in contact (integrally formed) with the side surface 2b opposite to the side surface 2a where the slit 4 is formed. Alternatively, it may be configured such that it is not in contact (formed apart).

  Further, as in a distribution circuit 1A as shown in FIG. 6, the main waveguide 2 and the branch waveguide 3 may be configured by a post-wall waveguide (PWW). The post wall waveguide is formed by a post wall 10 formed by plating a hole (through hole) between conductors (copper foils) formed on both surfaces of a printed circuit board (PCB). Electrically connected, and a large number of post walls 10 are arranged to form a rectangular waveguide. The first post 8 and the second post 9 are also formed by post walls (poles) 8e and 9e. In the distribution circuit 1A, as in the distribution circuit 1, by adjusting the position of the second post 9, it is possible to control the frequency characteristics while reducing the influence on the distribution characteristics.

(Array antenna)
Next, an array antenna 50 shown in FIG. 7 will be described as an embodiment of the present invention.
FIG. 7 is an exploded perspective view showing a schematic configuration of the array antenna 50.
In the following description, portions equivalent to those of the distribution circuit 1 are not described and are denoted by the same reference numerals in the drawings.

  As shown in FIG. 7, the array antenna 50 has a configuration in which a plurality of distribution circuits 1 are arranged. Specifically, the array antenna 50 has a configuration in which a plurality of branch waveguides 3 are arranged with respect to the main waveguide 2. A plurality of slots 52 that radiate electric power (electromagnetic field) supplied from a power feeding unit (not shown) to the external space are alternately arranged at predetermined intervals on the upper wall 51 of each branching waveguide 3. Is provided.

  The array antenna 50 of the present embodiment is configured by the distribution circuit 1 capable of controlling the frequency characteristics while reducing the influence on the distribution characteristics, thereby providing a stable frequency characteristic (antenna characteristics) as a planar antenna. In addition, it is possible to cope with downsizing and power saving.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

  In the present embodiment, FIG. 8 shows the result of calculating the reflection coefficient [dB] with respect to the change in the frequency [GHz] when the position of the second post 9 is changed in the X direction for the distribution circuit 1 by simulation. FIG. 9 shows the result of calculating the amplitude balance characteristic [dB] by simulation, and FIG. 10 shows the result of calculating the phase balance characteristic [dB] by simulation.

  In this simulation, the dimensions of each part of the distribution circuit 1 are shown in FIG. In addition, the calculation was performed with the thickness (height) of the main waveguide 2 and the branching waveguide 3 being 0.5 mm and the dielectric relative permittivity being 3.8.

  As for the position of the second post 9, as shown in FIG. 12, the origin (0) in the X direction was set to a position 0.175 mm away from the position along the extension line L2 of the corner C in the + direction. The position of the second post 9 is set to 4 levels X = −0.2, X = −0.1, X = 0, X = + 0.1 in 100 μm (0.1 mm) increments, and the design frequency is 60 GHz. Calculation by simulation was performed.

From the simulation results shown in FIGS. 8 to 10, when adjusting the position of the second post 9, the reflection loss (reflection coefficient) is the minimum even if the position of the second post 9 is changed within a range of 300 μm. It turns out that the frequency which becomes becomes suppressed to less than 5 GHz in the range of 60 GHz to 65 GHz. Therefore, it can be understood that the influence on the distribution characteristics due to the change in the frequency is small (sensitivity is low) as compared with the conventional case where the design parameters such as “d” and “q” shown in FIG. 14 are adjusted.
From the above, according to the present invention, it has become clear that the frequency characteristics can be precisely controlled while reducing the influence on the distribution characteristics.

  DESCRIPTION OF SYMBOLS 1 ... Distribution circuit 1A ... Distribution circuit (post-wall waveguide) 2 ... Main waveguide 3 ... Branch waveguide 4 ... Slit 5 ... 1st branch waveguide 6 ... 2nd branch waveguide 7 ... Partition wall 8 ... First post 8a ... Wall 8b, 8c ... Pole (pillar) 8e ... Post wall 9 ... Second post 9a, 9b, 9c ... Pole (pillar) 9d ... Wall 9e ... Post wall 10 ... Post wall 50 ... Array antenna 51 ... Upper wall 52 ... Slot P1 ... First port P2 ... First port P3 ... Third port P4 ... Fourth port

Claims (7)

A main waveguide having one end as a first port and the other end as a second port;
A first branching waveguide and a second branching waveguide having one end connected to the slit formed on the side surface of the main waveguide and the other end being a third port and a fourth port are parallel to each other. Branch waveguides formed side by side, and
Inside the main waveguide, a first post and a second post are arranged side by side along a side surface opposite to the side surface on which the slit is formed,
The first post is provided so as to protrude from the position facing the slit toward the inside of the main waveguide by a first protrusion amount,
The second post is positioned closer to the first port than the first post and has a second protrusion amount smaller than the first protrusion amount toward the inside of the main waveguide. A distribution circuit characterized by being provided protruding.   The said 2nd post is arrange | positioned in the position along the extension line of the corner | angular part where the one end of the said branching waveguide was connected to the said main waveguide, or its vicinity. Distribution circuit.   The distribution circuit according to claim 1, wherein the first post and / or the second post is formed of a wall.   3. The distribution circuit according to claim 1, wherein the first post and / or the second post includes at least one or a plurality of pillars.   5. The distribution according to claim 1, wherein the first post is provided so as to be biased toward the second port with respect to a center line of the branching waveguide. circuit.   The distribution circuit according to any one of claims 1 to 5, wherein the main waveguide and the branching waveguide are configured by post-wall waveguides.   An array antenna comprising the distribution circuit according to claim 1.