JP6033349B2 - Waveguide type slot array antenna and manufacturing method thereof - Google Patents

Description

  The present invention relates to a waveguide slot array antenna and a manufacturing method thereof.

  Waveguide slot array antennas such as waveguide slot array antennas with multiple slots formed on wide waveguide walls, and waveguide slot array antennas with slots formed on wide walls of substrate-type waveguides such as post-wall waveguides Array antennas are widely used. The waveguide slot array antenna can be operated in a microwave or millimeter wave band, and is expected to be applied to fields such as communication, radar, and sensors.

  As a document disclosing the waveguide slot array antenna, for example, Patent Document 1 is cited. In the waveguide slot array antenna described in Patent Document 1, a wall plate is formed inside a metal waveguide in which slots are formed, and the reflected wave at the slot is canceled by the reflected wave at the wall plate. Configuration is adopted.

JP 2005-167755 A (published June 23, 2005)

  By the way, in order to maximize the gain of the waveguide type slot array antenna having a plurality of slots (slot S1, slot S2,..., Slot Sn in order from the side closer to the power feeding section), these slots S1 to Sn are maximized. The amplitudes a1 to an of the electromagnetic waves output from the power may be made uniform. In order to make the amplitudes a1 to an of the electromagnetic waves output from these slots S1 to Sn uniform, the coupling amounts C1 to Cn of these slots S1 to Sn are set to C1 = 1 / n, C2 = 1 / ( n-1),..., Cn = 1. Here, the coupling amount Ci of the slot Si means the ratio of the power output from the slot Si to the power input to the waveguide slot array antenna.

  The reason why the equal amplitude excitation can be realized by setting the coupling amounts C1 to Cn of the slots S1 to Sn to C1 = 1 / n, C2 = 1 / (n−1),..., Cn = 1 is as follows. It is as follows. That is, for example, when the power input to the waveguide slot array antenna is 1 W, if the coupling amount C1 of the slot S1 is 1 / n, 1 / n of the power input to the waveguide slot array antenna. That is, 1 / n [W] of power is output from the slot S1. If the coupling amount C2 of the slot S2 is 1 / (n-1), 1 / (n-1) of 1-1 / n [W] remaining without being output from the slot S1, that is, 1 / n [ W] is output from the slot S2. Similarly, if the coupling amounts C3, C4, ..., Cn of the slots S3, S4, ..., Sn are 1 / (n-2), 1 / (n-3), ..., 1, 1 / n [W ] Is also output from the slots S3, S4,. The uniform power output from the slots S1 to Sn means that the amplitudes a1 to an of the electromagnetic waves output from the slots S1 to Sn are uniform. Therefore, equal amplitude excitation can be realized by setting the coupling amounts C1 to Cn of the slots S1 to Sn to C1 = 1 / n, C2 = 1 / (n-1),..., Cn = 1.

  In principle, it is impossible to set the coupling amount of the slot Sn to 1. Therefore, the gain C of the waveguide slot array antenna is approximately maximized by setting the coupling amount Cn of the slot Sn farthest from the feeding portion to a value as large as possible.

  In the conventional waveguide slot array antenna, the coupling amount Ci of each slot Si (i = 1, 2,..., N) is adjusted by changing the offset amount of the slot Si. The slots S1 to Sn have a property that the amount of coupling changes according to the distance from the central axis of the wide wall of the waveguide (the orthogonal projection of the central axis of the waveguide onto the wide wall) (schematically speaking). This is because the amount of coupling tends to decrease with increasing distance from the central axis of the wide wall of the waveguide).

  However, the offset amount of each slot Si cannot be made larger than the difference obtained by subtracting the slot width from ½ of the width of the waveguide. For this reason, in the conventional waveguide slot array antenna, when the number of slots is large, it is difficult to reduce the coupling amount of the slot S1 closest to the feeding portion to about 1 / n, and as a result, the gain is maximized There was a problem that it was difficult to approach the value.

  Hereinafter, it will be described with reference to a specific example that it is difficult to reduce the coupling amount of the slot S1 closest to the power feeding unit to about 1 / n. FIG. 6 is a plan view of a waveguide of a conventional waveguide slot array antenna 5. The waveguide type slot array antenna 5 has a slot 5s1 to a width of 0.2 mm on a wide wall 5a of a waveguide having a width of 1.94 mm and a height of 0.5 mm filled with a dielectric having a relative dielectric constant of 3.82. 6 pieces of 5s6 are formed. When this waveguide slot array antenna is operated at 60 GHz, the guide wavelength λg is 3.4 mm. Following the conventional design theory, the length of each slot 5si (i = 1, 2,..., 6) is λg / 2 = 1.7 mm, and the period of the slots 5s1 to 5s6 is λg = 3.4 mm. . Inside the waveguide of the waveguide slot array antenna 5, a control wall 5ci corresponding to each slot 5si is provided.

  In this waveguide slot array antenna 5, in order to excite the slots 5s1 to 5s6 with equal amplitude, it is necessary to set the coupling amount of the slot 5s1 closest to the power feeding portion to 1 / 6≈0.167. According to the conventional design method, the offset amount Δ of the slot 5s1 necessary for this is 0.72 mm. At this time, the interval δ between the slot 5s1 and the narrow wall 5b is δ = 1.94 (waveguide width) /2−0.72 (offset amount) −0.2 (slot width) = 0.05 mm. . In this way, it is extremely difficult to manufacture the slot close to the narrow wall by using a widely used printed circuit board manufacturing technique. As the number of slots increases, it becomes necessary to further reduce the coupling amount of the slot 5s1 closest to the power supply unit, so it is clear that this difficulty is spurred.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to maximize the gain (gain when all the slots are equally amplitude excited) more easily than the conventional waveguide slot array antenna. An object of the present invention is to realize a waveguide slot array antenna that can be made close to.

  In order to solve the above problems, a waveguide slot array antenna according to the present invention includes a slot group formed on a wide wall of the waveguide, and a control wall group formed inside the waveguide. In the waveguide slot array antenna, for two or more continuous slots included in the slot group, the length of the slot measured along the tube axis of the waveguide increases as the distance from the power feeding unit increases. The distance from the slot seen from the direction orthogonal to the wide wall to the corresponding control wall becomes shorter as the distance from the power feeding unit increases.

  According to the above configuration, the amplitude of the electromagnetic wave output from each slot at a specific frequency is made uniform without changing the offset amount of each of the two or more consecutive slots included in the slot group. Or it can be made substantially uniform. That is, the gain at the specific frequency can be made closer to the maximum value (gain when all slots are excited with equal amplitude) more easily than the conventional waveguide slot array antenna.

  In the waveguide slot array antenna according to the present invention, it is preferable that the two or more continuous slots include a slot closest to the feeding portion in the slot group.

  According to the above configuration, the amplitude of the electromagnetic wave output from each slot at a specific frequency is uniform for two or more consecutive slots including the slot closest to the power feeding unit without changing the offset amount of each slot. Or substantially uniform. As a result, unlike the conventional waveguide slot array antenna, the gain at the specific frequency can be made close to the maximum value without causing the problem that it becomes difficult to manufacture the slot closest to the feeding portion.

  In the waveguide slot array antenna according to the present invention, it is preferable that the offset amount of each slot is uniform for the two or more consecutive slots.

  According to said structure, the problem that manufacture of the slot nearest to an electric power feeding part becomes difficult can be avoided more reliably.

  In the waveguide slot array antenna according to the present invention, it is preferable that the amplitude of the electromagnetic wave output from each slot is uniform or substantially uniform for the two or more consecutive slots.

  According to said structure, the gain in a specific frequency can be made to approach a maximum value more reliably.

  In the waveguide slot array antenna according to the present invention, the waveguide is a post wall waveguide, and the control wall is a plurality of conductors arranged in a fence shape inside the dielectric layer constituting the waveguide. It is preferably a set of posts.

  According to said structure, compared with the case where the said waveguide is a metal waveguide, and compared with the case where the said control wall is a metal plate, a lighter and smaller waveguide type slot array antenna is obtained. Can be realized. Further, since it becomes possible to manufacture using a printed circuit board technology, a waveguide slot array antenna with a lower profile can be realized.

  In order to solve the above problems, a method of manufacturing a waveguide slot array antenna according to the present invention includes a slot group formed on a wide wall of a waveguide, and a control wall group formed inside the waveguide. The slot length measured along the tube axis of the waveguide from two or more continuous slots included in the slot group is determined from the feeder section. And a step of setting the distance from the slot viewed from a direction orthogonal to the wide wall to be shorter as the distance from the power feeding unit is shorter. To do.

  According to the above configuration, the amplitude of the electromagnetic wave output from each slot at a specific frequency is made uniform without changing the offset amount of each of the two or more consecutive slots included in the slot group. Or it can be made substantially uniform. That is, the gain can be made closer to the maximum value (gain when all the slots are excited with equal amplitude) more easily than the conventional waveguide slot array antenna.

  According to the present invention, the gain can be made closer to the maximum value (gain when all the slots are excited with equal amplitude) more easily than the conventional waveguide slot array antenna.

1 is an exploded perspective view of an antenna module including a waveguide slot array antenna according to an embodiment of the present invention. It is sectional drawing of the waveguide type slot array antenna shown in FIG. It is a top view of the waveguide of the waveguide type slot array antenna shown in FIG. 2 is a graph showing the frequency dependence of the coupling amount of slots in the waveguide slot array antenna shown in FIG. One is a graph obtained when the slot length is 1.65 mm and the offset amount is 0.65 mm, and the other is when the slot length is 1.9 mm and the offset amount is 0.65 mm. It is a graph obtained. 3 is a graph showing the direction dependence of gain in the zx plane of the waveguide slot array antenna shown in FIG. 1. One is a graph (Example) obtained when the slot coupling amount is gradually increased as the distance from the power supply unit increases, and the other is a graph (Comparative Example) obtained when the slot coupling amount is made uniform. . It is a top view of the waveguide of the conventional waveguide type slot array antenna.

[Configuration of antenna module including waveguide slot array antenna]
A configuration of an antenna module 1 including a waveguide slot array antenna 1A according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is an exploded perspective view of an antenna module 1 including a waveguide slot array antenna 1A.

  As shown in FIG. 1, the antenna module 1 includes a waveguide slot array antenna 1A and a waveguide 1B.

  The waveguide slot array antenna 1A has a structure in which a first conductor layer 11, a first dielectric layer 12, and a second conductor layer 13 are laminated in this order. In other words, the waveguide slot array antenna 1 </ b> A includes the first dielectric layer 12 and the first conductor layer 11 and the second conductor layer 13 that face each other with the first dielectric layer 12 interposed therebetween. Has been. The first conductor layer 11, the first dielectric layer 12, and the second conductor layer 13 are arranged so that the principal surface is parallel to the xy plane in the illustrated coordinate system, and are laminated in the z-axis direction. The

  Arbitrary conductors can be used as the material of the first conductor layer 11 and the second conductor layer 13, and for example, a metal such as copper can be used. As the material of the first dielectric layer 12, any dielectric can be used. For example, glass such as quartz glass, fluorine resin such as PTFE (polytetrafluoroethylene), liquid crystal polymer, or cycloolefin A polymer or the like can be used.

  The first conductor layer 11 is formed with a slot group including a plurality (six in this embodiment) of slots 11d1 to 11d6. Each slot 11dj (j = 1, 2,..., 6) is a rectangular opening having a long side substantially parallel to the y-axis (parallel in the present embodiment) in the illustrated coordinate system. These slots 11d1 to 11d6 are arranged along the y-axis in the illustrated coordinate system. A more specific arrangement example of the slots 11d1 to 11d6 will be described later with reference to another drawing.

  A post wall 12 a is formed inside the first dielectric layer 12. The post wall 12a is a set of M conductor posts 12a1 to 12aM arranged in a fence shape. The central axes of the conductor posts 12a1 to 12aM constituting the post wall 12a are (1) a first plane parallel to the zx plane and (2) an end on the y-axis negative direction side in the illustrated coordinate system. A second plane parallel to the yz plane that is connected to the edge on the x-axis positive direction side of the plane, and (3) an edge on the x-axis positive direction side is connected to an edge on the y-axis positive direction side of the second plane. , A third plane parallel to the zx plane, (4) an end on the y-axis positive direction side is connected to an end on the x-axis negative direction side of the third plane, and an end on the y-axis negative direction side is the first side A fourth surface parallel to the yz plane, which is connected to the end on the x-axis negative direction side of the plane is stretched.

  Each of the conductor posts 12ai (i = 1, 2,..., M) constituting the post wall 12a is a cylinder whose upper end is connected to the first conductor layer 11 and whose lower end is connected to the second conductor layer 13. Or cylindrical conductor. A more specific configuration example of each conductor post 12ai constituting the post wall 12a will be described later with reference to another drawing.

  The conductor posts 12a1 to 12aM constituting the post wall 12a are arranged at intervals sufficiently shorter than the wavelength λ of the electromagnetic wave propagating through the waveguide 1A1. Therefore, a rectangular parallelepiped region surrounded on all sides by the post wall 12a and sandwiched between the first conductor layer 11 and the second conductor layer 13 functions as the waveguide 1A1 of the waveguide slot array antenna 1A. To do. At this time, the post wall 12a functions as a narrow wall of the waveguide 1A1, and the first conductor layer 11 and the second conductor layer 13 function as a wide wall of the waveguide 1A1. In the following description, the first plane, the second plane, the third plane, and the fourth plane, which are stretched by the conductor posts 12a1 to 12aM, are respectively represented by the rear narrow wall of the waveguide 1A1. It is also described as a right narrow wall, a front narrow wall, and a left narrow wall (the front narrow wall and the rear narrow wall of the waveguide 1A1 are sometimes called short walls). Further, the first conductor layer 11 and the second conductor layer 13 are also referred to as an upper wide wall and a lower wide wall, respectively. However, these names are convenient names for distinguishing the four narrow walls or the two wide walls from each other, and do not impose any restrictions on the arrangement of the waveguide slot array antenna 1A.

  The same number of control walls 12c1 to 12c6 as slots 11d1 to 11d6 are further formed inside first dielectric layer 12 (slots 11d1 to 11d6 and control walls 12c1 to 12c6 correspond one-to-one). . Each control wall 12cj (j = 1, 2,..., 6) is a set of a plurality (five in the present embodiment) of conductor posts 12cj1 to 12cj5 arranged in a fence shape. The central axes of the conductor posts 12cj1 to 12cj5 constituting each control wall 12cj form a plane substantially parallel to the zx plane (parallel in this embodiment) in the illustrated coordinate system. These control walls 12c1 to 12c6 are arranged in parallel with the y-axis in the illustrated coordinate system. A more specific arrangement of the control walls 12c1 to 12c6 will be described later with reference to another drawing.

  Each conductor post 12cjk (k = 1, 2,..., 5) constituting the control wall 12cj is a cylinder whose upper end is connected to the first conductor layer 11 and whose lower end is connected to the second conductor layer 13. Conductor. A more specific configuration example of each conductor post 12cjk constituting the control wall 12cj will be described later with reference to another drawing.

  The conductor posts 12cj1 to 12cj5 constituting the control wall 12cj are arranged at intervals sufficiently shorter than the wavelength λ of the electromagnetic wave propagating through the waveguide 1A1. Thereby, the control wall 12cj functions as a reflection wall that reflects the electromagnetic wave propagating through the waveguide 1A1.

  An opening 13 a is formed in the second conductor layer 13. The waveguide 1B is connected to the waveguide slot array antenna 1A so that the internal cavity that functions as the waveguide 1B1 communicates with the waveguide 1A1 of the waveguide slot array antenna 1A through the opening 13a.

  The waveguide 1B is a power feeding unit that feeds (inputs) electromagnetic waves to the waveguide slot array antenna 1A. The waveguide 1B is a tubular member whose both ends are open, and its tube wall is made of a conductor such as metal. The cavity formed inside the waveguide 1B may be filled with air or may be filled with a dielectric other than air, but in the present embodiment, the former configuration is adopted. That is, in this embodiment, a hollow waveguide is used as the waveguide 1B.

  The electromagnetic wave propagating in the z-axis positive direction through the waveguide 1B1 of the waveguide 1B enters (1) the waveguide 1A1 of the waveguide slot array antenna 1A through the opening 13a, and (2) the waveguide slot array. It propagates along the waveguide 1A1 of the antenna 1A in the positive y-axis direction and (3) exits to the outside via the slots 11d1 to 11d6. At this time, reflection occurs in the slots 11d1 to 11d6, but the reflected wave generated in each slot 11dj is canceled by the reflected wave generated in the corresponding control wall 12cj. That is, by providing the control walls 12c1 to 12c6 in the waveguide 1A1, it is possible to suppress the reflection loss that occurs in the waveguide 1A1.

  Note that the coordinate system shown in FIG. 1 is determined as follows. (1) The longitudinal axis of the waveguide 1A1 of the waveguide slot array antenna 1A is the y-axis. The direction of the y-axis is determined so that the direction from the feeding portion of the waveguide 1A1 toward the tip of the waveguide 1A1 is a positive direction. (2) The axis parallel to the thickness direction of the first dielectric layer 12 is taken as the z-axis. The direction of the z-axis is determined so that the direction from the second conductor layer 13 toward the first conductor layer 11 is a positive direction. (3) The axis orthogonal to both the y-axis and the z-axis described above is taken as the x-axis. The direction of the x axis is determined so that the x axis forms a right-handed system together with the y axis and the z axis described above.

Note that “viewed from above” in this specification refers to viewing an object from the positive z-axis direction in the coordinate system defined as described above. In addition, the “waveguide direction” in this specification refers to the positive y-axis direction in the coordinate system defined as described above. In addition, “in-tube wavelength” in this specification refers to a wavelength λg given as follows. That is, the TE ₁₀ mode that guides a rectangular parallelepiped waveguide such as the waveguide 1A1 is a combination of two plane waves. An angle θ formed by the propagation direction of these two plane waves and the tube axis direction of the waveguide 1A1 satisfies cos (θ) = {1− (fc / f) ² } ^1/2 . Here, f is a frequency, and fc is a cutoff frequency of the waveguide 1A1. The wavelength λ of the plane wave propagating through the waveguide 1A1 is given by λ = c / f / ε _r ^1/2 (c is the speed of light and ε _r is the relative dielectric constant). The guide wavelength λg is given by λg = λ / cos (θ).

[Configuration example of conductor post]
A configuration example of each conductor post 12ai constituting the post wall 12a and each conductor post 12cjk constituting the control wall 12cj will be described with reference to FIG. FIG. 2 is a cross-sectional view of the waveguide slot array antenna 1A in a cross section parallel to the zx plane passing through the control wall 12cj.

  As described above, the post wall 12a is a set of M conductor posts 12a1 to 12aM arranged in a fence shape, and each conductor post 12ai has an upper end connected to the first conductor layer 11 and a lower end thereof. Is a cylindrical or columnar conductor connected to the second conductor layer 13.

  For example, as shown in FIG. 2, the conductor post 12 ai is a conductor plating layer formed on the wall surface of the through hole formed in the first conductor layer 11, the first dielectric layer 12, and the second conductor layer 13. (In this case, the conductor post 12ai can be regarded as a cylindrical conductor).

  The conductor post 12ai may have a hollow structure, and the inside may be filled with an arbitrary dielectric or conductor (when filled with a conductor, the conductor post 12ai can be regarded as a cylindrical conductor. ).

  As described above, the control wall 12cj is a set of five conductor posts 12cj1 to 12cj5 arranged in a fence shape, and the upper ends of the conductor posts 12cj1 to 12cj5 are connected to the first conductor layer 11, The lower end is a cylindrical or columnar conductor connected to the second conductor layer 13.

  The conductor post 12cjk can be constituted by a conductor plating layer formed on the wall surface of the through hole formed in the first dielectric layer 12, for example, as shown in FIG. 2 (in this case, the conductor post 12cjk is It can be thought of as a cylindrical conductor). The conductor post 12cjk may have a hollow structure, and the inside may be filled with an arbitrary dielectric or conductor (when the conductor post 12cjk is filled with a conductor, the conductor post 12cjk is regarded as a cylindrical conductor. )

[Arrangement of control walls and slots]
Next, the arrangement of the slots 11d1 to 11d6 and the control walls 12c1 to 12c6 in the waveguide slot array antenna 1A will be described with reference to FIG. FIG. 3 is a plan view of the waveguide 1A1 of the waveguide slot array antenna 1A. In FIG. 3, instead of illustrating the conductor posts 12a1 to 12aM constituting the post wall 12a, the wall core surfaces (planes on which the central axes of the conductor posts 12a1 to 12aM constituting the post wall 12a are stretched) are illustrated. ing.

  Each slot 11dj (j = 1, 2,..., 6) has a long side which is formed on the upper wide wall of the waveguide 1A1 and is substantially parallel to the tube axis of the waveguide 1A1 (parallel in this embodiment). It is a rectangular opening, and the slots 11d1 to d6 are arranged along the tube axis of the waveguide 1A1. The slots 11d1 to d6 may be arranged on the left side or the right side of the central axis L of the upper wide wall (the orthogonal projection of the tube axis of the waveguide 1A1 onto the upper wide wall). In the embodiment, the former arrangement is adopted.

  The length (long side length) Lsj of each slot 11dj may be about ½ of the in-tube wavelength λg of the waveguide slot array antenna 1A, and in order to realize equal amplitude excitation of the slots 11d1 to 11d6, As will be described later, an individual value is set for each slot. The width (short side length) Wsj of each slot 11dj is not particularly limited, but is uniformly set to 0.2 mm in the present embodiment.

  The center distance D between two adjacent slots 11dj, 11dj + 1 (j = 1, 2,..., 5) measured along the tube axis of the waveguide 1A1 is equal to the waveguide wavelength λg of the waveguide slot array antenna 1A. It is only necessary to have the same degree, and in the present embodiment, it is uniformly set to 3.4 mm.

  The offset amount Δj of each slot 11dj, that is, the distance from the central axis L of the upper wide wall of the waveguide 1A1 to the slot 11dj is set to the waveguide width W (in the present embodiment, 1.94 mm). Is equal to the difference W / 2−Wsj obtained by subtracting the slot width Wsj (set to 0.2 mm in the present embodiment) of the slot 11dj from 1/2 of the slot 11d1, and the equal amplitude excitation of the slots 11d1 to 11d6 In order to realize this, an individual value is set for each slot as described later. In the configuration of the present embodiment, the distance between the right long side of the slot 11dj and the central axis L of the upper wide wall of the waveguide 1A1 is the offset amount Δj.

  Each control wall 12cj (j = 1, 2,..., 6) has a wall core surface that is formed inside the waveguide 1A1 and is substantially orthogonal (or orthogonal in the present embodiment) to the tube axis of the waveguide 1A1. It is a wall and is arranged so that the extension of the wall core surface intersects with the vicinity of the center of the corresponding slot 11dj. When the control wall 12cj is composed of a plurality of conductor posts 12cj1 to 12cj5, the surface on which the central axis of these conductor posts 12cj1 to 12cj5 extends is the wall core surface. Each control wall 12cj may be arranged on the right side or the left side of the corresponding slot 11dj, but the former arrangement is adopted in the present embodiment.

  The width Wcj of each control wall 12cj may be about ½ of the width W of the waveguide 1A1, and is uniformly set to 0.8 mm in the present embodiment. In the configuration of the present embodiment, the distance between the central axis of the rightmost conductor post 12cj1 and the central axis of the leftmost conductor post 12cj5 is the width Wcj of the control wall 12cj.

  The relative position of each control wall 12cj to the corresponding slot 11dj is defined by two parameters dxj and dyj. Here, dxj is measured from the right end (long side on the control wall 12cj side) of the slot 11dj measured along the axis (x-axis in FIG. 3) orthogonal to the central axis L in the upper wide wall of the waveguide 1A1. This is the distance to the control wall 12cj. In other words, it is the distance from the slot 11dj to the control wall 12cj as seen from the direction orthogonal to the upper wide wall of the waveguide 1A1. In the configuration of the present embodiment, the length of a perpendicular line extending from the center point of the upper end surface of the leftmost conductor post 12cj5 to the right long side of the slot 11dj is dxj. On the other hand, dyj is a control wall from the rear end (short side on the incident side) of the slot 11dj measured along an axis parallel to the central axis L (y-axis in FIG. 3) in the upper wide wall of the waveguide 1A1. It is the distance to 12cj. In the configuration of the present embodiment, the length of the perpendicular line extending from the center point of the upper end surface of each conductor post 12cjk to the extended line of the rear short side of the slot 11dj is dyj. These two parameters dxj and dyj are set to individual values for each slot as will be described later in order to realize equal amplitude excitation in the slots 11d1 to 11d6.

[Parameter setting example for each slot]
Next, an example of setting parameters Lsj, dxj, dyj, and Δj for each slot 11dj will be described.

  First, the following relationship exists between the length Lsj of each slot 11dj and the coupling amount Cj and resonance frequency fj of the slot 11dj. That is, when the length Lsj is increased, the coupling amount Cj is increased, but the resonance frequency fj is decreased. Further, there is the following relationship between the distance dxj from each slot 11dj to the corresponding control wall 12cj (see the previous section for a more accurate definition of dxj) and the resonance frequency fj of the slot 11dj. . That is, when the distance dxj is reduced, the resonance frequency fj is increased.

  Therefore, if the length Lsj of a certain slot 11dj is increased and the distance dxj from the slot 11dj to the corresponding control wall 12cj is decreased, the resonance frequency of the slot 11dj is hardly changed. The coupling amount Cj can be increased. Further, if the length Lsj of a slot 11dj is shortened and the distance dxj from the slot 11dj to the corresponding control wall 12cj is increased, the resonance frequency fj of the slot 11dj is hardly changed, and the slot 11dj The coupling amount Cj can be reduced.

  FIG. 4 shows the case where (1) Lj = 1.65 mm, dxj = 0.62 mm, dyj = 0.877 mm, Δj = 0.65 mm, and (2) Lj = 1.9 mm, dxj = 0.42 mm. , Dyj = 1.012 mm, and Δj = 0.65 mm are graphs showing the frequency dependence of the coupling amount Cj of the slot 11dj.

  Referring to FIG. 4, the following can be confirmed. That is, even if the offset amount Δj is set to the same value (0.65), the length Lj is set to a different value (1.65, 1.9). It can be seen that the coupling amount Cj can be a different value. Further, the amount of coupling Cj is larger when the length Lj is set to a large value (1.9) than when the length Lj is set to a small value (1.65). Is confirmed.

  In the present embodiment, based on these facts, parameters Lsj, dxj, dyj, and Δj for each slot 11dj are set as shown in Table 1 below.

  When the parameters Lsj, dxj, dyj, and Δj for each slot 11dj are set as shown in Table 1 above, the coupling amount Cj for each slot 11dj is as follows.

C1 = 0.166 (≒ 1/6),
C2 = 0.2 (= 1/5),
C3 = 0.25 (= 1/4),
C4 = 0.33 (≒ 1/3),
C5 = 0.50 (= 1/2),
C6 = 0.65.

  Therefore, the power Pj output from each slot 11dj when 1W of power is input is as follows.

P1 = 1 × 0.166 = 0.166 W,
P2 = (1−0.166) × 0.2 = 0.1668 W,
P3 = (1−0.166−0.1668) × 0.25 = 0.1688 W,
P4 = (1−0.166−0.1668−0.1668) × 0.33 = 0.165132 W,
P5 = (1−0.166−0.1668−0.1668−0.165132) × 0.5 = 0.167634 W,
P6 = (1−0.166−0.1668−0.1668−0.165132−0.167634) × 0.65 = 0.1089 W.

  That is, when the parameters Lsj, dxj, dyj, and Δj for each slot 11dj are set as shown in Table 1 above, equal amplitude excitation is realized in the slots 11d1 to 11d5 other than the slot 11d6 farthest from the power feeding unit.

  In Table 1, the following points should be noted.

  (1) Regarding the four consecutive slots 11d1 to 11d4 included in the slots 11d1 to 11d6 (slot group), the lengths Ls1 to Ls4 are gradually increased as the distance from the power feeding unit increases, so that the offset amounts Δ1 to Δ4 are uniform. However, the amount of coupling C1 to C4 can be gradually increased as the distance from the power feeding unit increases, and as a result, the amplitude of the electromagnetic waves output from these slots 11d1 to 11d4 can be made uniform or substantially uniform.

  (2) With respect to four consecutive slots 11d1 to 11d4 included in the slots 11d1 to 11d6 (slot group), the distances dx1 to dx4 to the corresponding control walls 12c1 to 12c4 are gradually decreased as the distance from the power feeding unit increases. Resonance frequencies f1 to f4 can be made substantially uniform even when the lengths Ls1 to Ls4 gradually increase as the distance from the power feeding unit increases.

  (3) The offset amount Δj is 0.65 mm or less, and as a result, the distance (W / 2−Wsj−Δj) between the slot 11dj and the left narrow wall of the waveguide 1A1 is 0.3 mm or more.

  As described above, the amount of coupling Cj required for realizing equal amplitude excitation is relatively small (specifically, smaller than 0.5), that is, the slots 11d1 to 11d4, that is, the slots 11d1 to 11d1 close to the power feeding unit. For 11d4, the desired coupling amounts C1 to C4 are obtained by changing the length Lsj without changing the offset amounts Δ1 to Δ4. On the other hand, for the slots 11d5 to 11d6 in which the coupling amount Cj required for realizing equal amplitude excitation is relatively large (specifically 0.5 or more), that is, the slots 11d5 to 11d6 far from the power feeding unit. The desired coupling amounts C5 to C6 are obtained by changing the lengths Ls5 to Ls6 and changing the offset amounts Δ5 to Δ6.

  In this way, by changing both the length Lsj and the offset amount Δj, the coupling amount C5 (0.5) required for realizing equal amplitude excitation can be obtained even for the slot 11d5 far from the power feeding unit. Can do. Note that the coupling amount C6 required for realizing equal amplitude excitation is 1 for the slot 11d6 farthest from the power feeding unit. However, it is impossible in principle to set the coupling amount C6 of the slot 11d6 to 1. Therefore, in the present embodiment, the parameters Ls6, L6 are set so that the coupling amount C6 of the slot 11d6 is as large as possible (specifically, 0.65), that is, the illuminance distribution is as close to equal amplitude excitation as possible. The values of dx6, dy6, and Δ6 are set.

(Verification of effect)
Next, when the parameters Lsj, dxj, dyj, and Δj relating to each slot 11dj are set as shown in Table 1 above (Example), the parameters Lsj, dxj, dyj, and Δj are determined based on the coupling amount Cj of each slot 11dj. The gain obtained is compared with the case where it is set to be uniformly 0.34 (comparative example).

  FIG. 5 is a graph showing the direction dependency of the gain in the zx plane regarding the example and the comparative example. In the graph shown in FIG. 5, the horizontal axis θ is taken such that the positive x-axis direction is + 90 °, the positive z-axis direction is 0 °, and the negative x-axis direction is −90 °.

  Referring to FIG. 5, the following can be confirmed. That is, it can be confirmed that the gain in the positive z-axis direction is the highest in both the example and the comparative example. Further, comparing the example and the comparative example, the directivity of the example is sharper than the directivity of the comparative example, and the maximum gain of the example (gain in the z-axis positive direction) is the maximum gain of the comparative example. It is confirmed that it is bigger than.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. For example, other embodiments obtained by appropriately combining the technical means included in the above-described embodiments are also included in the technical scope of the present invention.

  For example, in the above-described embodiment, four consecutive slots included in the slot group formed on the wide wall of the waveguide, including the slot closest to the feeding portion, are (1) along the tube axis of the waveguide. (2) The distance from the slot viewed from the direction orthogonal to the wide wall of the waveguide to the corresponding control wall decreases as the distance from the power supply section increases. Although the condition is assumed to be satisfied, the present invention is not limited thereto. That is, when there are two or more consecutive slots satisfying these conditions, two or more consecutive slots satisfying these conditions are satisfied regardless of whether or not these slots include a slot closest to the power feeding unit. As compared with the case where no is present, there is an effect that the gain is brought close to the maximum value (gain when all the slots are equiamplitude excited).

  For example, in the above-described embodiment, a configuration (see FIG. 1) in which power supply to the waveguide slot array antenna is performed using a waveguide is employed, but the present invention is not limited to this. That is, for example, a configuration in which power is supplied to the waveguide slot array using a microstrip line may be employed.

  Further, in the above-described embodiment, the configuration in which the slot is arranged along the left narrow wall and the control wall corresponding to the right side is arranged (see FIG. 3) is adopted, but the present invention is not limited to this. That is, for example, a configuration may be adopted in which the slot is arranged along the right narrow wall and the control wall corresponding to the left side thereof is arranged. In addition, a configuration is adopted in which slots along the right narrow wall and slots along the left narrow wall are alternately arranged, and a control wall is arranged on the left side of the slot along the right narrow wall and the right side of the slot along the left narrow wall. May be. In this case, the center interval between the right slot and the left slot adjacent to each other measured along the tube axis of the waveguide may be ½ of the guide wavelength λg.

  The present invention can be suitably used for, for example, a waveguide slot array antenna or a waveguide slot array mounted on a communication device, a radar device, or the like.

DESCRIPTION OF SYMBOLS 1 Antenna module 1A Waveguide type slot array antenna 1A1 Waveguide 11 1st conductor layer (wide wall)
11dj slot 12 first dielectric layer 12a post wall 12ai conductor post 12cj control wall 12cjk conductor post 13 second conductor layer 13a opening 1B waveguide 1B1 waveguide Lsj slot length dxj From slot to corresponding control wall Distance Δj Slot offset

Claims (6)

A waveguide slot array antenna comprising a slot group formed on a wide wall of a waveguide and a control wall group formed inside the waveguide,
For two or more consecutive slots included in the slot group, the length of the slot measured along the tube axis of the waveguide becomes longer as the distance from the feeding portion increases, and the slot is viewed from the direction orthogonal to the wide wall. The distance from the corresponding control wall to the corresponding control wall decreases as the distance from the power feeding unit increases.
A waveguide type slot array antenna. The two or more consecutive slots include a slot closest to the power feeding unit in the slot group.
The waveguide type slot array antenna according to claim 1. For the two or more consecutive slots, the offset amount of each slot is uniform.
The waveguide type slot array antenna according to claim 2. For the two or more consecutive slots, the amplitude of the electromagnetic wave output from each slot is uniform or substantially uniform.
The waveguide slot array antenna according to claim 3. The waveguide is a post wall waveguide, and the control wall is a set of a plurality of conductor posts arranged like a fence inside a dielectric layer constituting the waveguide.
The waveguide slot array antenna according to any one of claims 1 to 4, wherein A method of manufacturing a waveguide slot array antenna having a slot group formed on a wide wall of a waveguide and a control wall group formed inside the waveguide,
For two or more consecutive slots included in the slot group, the length of the slot measured along the tube axis of the waveguide is set to become longer as the distance from the power feeding unit increases, and is orthogonal to the wide wall. Including a step of setting the distance from the slot viewed from the direction to the corresponding control wall to be shorter as the distance from the power feeding unit is increased.
A method for manufacturing a waveguide slot array antenna.

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