Antenna equipment

Abstract

To provide an antenna device that can suppress the effects of multiple reflected waves, regardless of the direction in which the multiple reflected waves are received. [Solution] The antenna device comprises a transmitting / receiving unit 20, a substrate 10, and an antenna unit 30. The antenna unit includes a plurality of waveguide forming units 31, 32, each laminated in the lamination direction, each containing resin, and bonded to one another. The waveguide forming unit at one end in the lamination direction has an antenna surface 321 having a resin exposed portion 3211 where the resin is exposed. The waveguide forming unit at the other end in the lamination direction has a substrate-facing surface 312 that is bonded to the substrate. The first waveguide forming unit has a first waveguide surface 322 that is bonded to the second waveguide forming unit. The second waveguide forming unit has a second waveguide surface 311 that is bonded to the first waveguide forming unit. At least one of the substrate-facing surface, the first waveguide surface, and the second waveguide surface has a plurality of leakage recesses 41 formed in the lamination direction, and a leakage suppression portion 40 formed including a portion that overlaps with the resin exposed portion in the lamination direction.

Description

Technical Field

[0001] The present disclosure relates to an antenna device.

Background Art

[0002] Conventionally, a radar system including an antenna capable of suppressing the influence on reflected waves from a sensor cover has been known (see, for example, Patent Document 1). The antenna included in this radar system has a plurality of transmitting and receiving antenna elements on the front surface facing the sensor cover, and the front surface of the antenna is formed obliquely rather than parallel to the antenna elements. By forming the front surface of the antenna in this way, the antenna surface reflects the reflected waves from the sensor cover in an inclined direction, and the reflected waves can be scattered. As a result, the multiple reflected waves that are reflected multiple times between the sensor cover arranged horizontally with respect to the front surface of the antenna and the antenna propagate in a direction different from the direct waves directly transmitted and received by the antenna, so the influence of the multiple reflected waves is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Now, suppose the antenna is positioned, for example, inside the bumper of a vehicle, and the bumper is not horizontal to the front of the antenna, but curved towards the antenna. In this case, even if the reflected wave received from the bumper is reflected in a direction tilted towards the receiving direction, there is a risk that the reflection will not be scattered. As a result, compared to the case where the bumper is formed horizontally to the front of the antenna, the difference in path length of each reflected wave reflected multiple times between the bumper and the antenna becomes smaller, and the phase difference of each of these reflected waves received by the antenna becomes smaller. Consequently, the multiple reflected waves received by the antenna will not cancel each other out, making it difficult to suppress the effects of multiple reflected waves. Thus, the method for suppressing the effects of multiple reflected waves described in Patent Document 1 may not be able to suppress the effects of multiple reflected waves depending on the receiving direction of the reflected wave that causes the multiple reflection.

[0005] In view of the above, this disclosure aims to provide an antenna device that can suppress the effects of multiple reflected waves regardless of the direction in which the reflected wave is received. [Means for solving the problem]

[0006] According to one perspective of this disclosure, The antenna device is A transmitting and receiving unit (20) that transmits and receives radio waves, A circuit board (10) on which the transmitting and receiving unit is located, An antenna section (30) provided on a substrate and forming a waveguide for propagating radio waves, and comprising, The antenna section includes a plurality of waveguide forming sections (31, 32) which are stacked in the stacking direction when the alignment direction of the substrate and the antenna section is defined as the stacking direction, and each of them is made up of resin. Multiple waveguide forming sections are bonded together when adjacent waveguide forming sections are in the stacking direction. Of the multiple waveguide forming sections, the waveguide forming section at one end in the stacking direction has an antenna surface (321) for transmitting radio waves on one side in the stacking direction. Of the multiple waveguide forming portions, the waveguide forming portion at the end on the other side in the stacking direction has a substrate-facing surface (312) on the other side in the stacking direction that is bonded to the substrate. When one of two adjacent waveguide forming sections in the stacking direction is designated as the first waveguide forming section (32), and the other of two adjacent waveguide forming sections in the stacking direction is designated as the second waveguide forming section (31), The first waveguide forming section has a first waveguide surface (322) on the other side in the stacking direction that is bonded to the second waveguide forming section. The second waveguide forming section has a second waveguide surface (311) on one side in the stacking direction that is bonded to the first waveguide forming section. The antenna surface has a resin exposed portion (3211) in which resin is exposed in at least a part of it. At least one of the substrate-facing surface, the first waveguide surface, and the second waveguide surface has a leakage suppression section (40) that suppresses the leakage of radio waves from between it and the opposing surface. The leakage suppression section is made of a material with higher electrical conductivity than resin and has multiple leakage recesses (41, 42, 43) formed in the lamination direction. The exposed resin portion is formed to include a portion that overlaps with the leakage suppression portion in the lamination direction.

[0007] Waveguide forming sections, which contain resin, reflect waves less easily compared to those made of materials with relatively high electrical conductivity, such as metal. Therefore, when reflected waves propagate to the exposed resin section, most of these reflected waves propagate from the exposed resin section into the waveguide forming section. The reflected waves propagating into the waveguide forming section lose energy through heat exchange as they pass through the resin-containing waveguide forming section. Consequently, regardless of the direction in which the antenna surface receives the reflected wave, the received reflected wave is less likely to be reflected by the antenna surface. This suppresses the generation of multiple reflected waves, which are caused by repeated reflections of radio waves by the antenna surface, and thus reduces the effects of multiple reflected waves.

[0008] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0009] [Figure 1] It is an exploded perspective view of a part of the antenna device according to the first embodiment as viewed from one side in the stacking direction. [Figure 2] It is an exploded perspective view of a part of the antenna device according to the first embodiment as viewed from the other side in the stacking direction. [Figure 3] It is a diagram showing a part of the cross section III-III of FIG. 1. [Figure 4] It is an enlarged view of part IV of FIG. 3. [Figure 5] It is an explanatory diagram for explaining the relationship between the radio wave leakage suppression effect of the leakage suppression part according to the first embodiment and the depression depth. [Figure 6] It is an exploded perspective view of a part of the first comparative antenna as viewed from one side in the stacking direction. [Figure 7] It is an exploded perspective view of a part of the first comparative antenna as viewed from the other side in the stacking direction. [Figure 8] It is a part of the cross-sectional view VIII-VIII of FIG. 6 and is a view corresponding to FIG. 3 of the antenna device. [Figure 9] It is an enlarged view of part IX of FIG. 8 and is a view corresponding to FIG. 4 of the antenna device. [Figure 10] It is a diagram showing the shape of the reflection suppression part of the first comparative antenna. [Figure 11] It is an explanatory diagram for explaining the reflection direction of the reflected wave reflected by the reflection suppression part according to the first comparative antenna. [Figure 12] It is a diagram showing the relationship between the reflection suppression effect of the reflection suppression part of the first comparative antenna and the size of the reflection suppression depression part. [Figure 13] It is a diagram showing different shapes of the reflection suppression part of the first comparative antenna. [Figure 14] It is an explanatory diagram for explaining the reflection direction of the reflected wave reflected by the reflection suppression parts with different shapes according to the first comparative antenna. [Figure 15] It is a diagram showing different shapes of the reflection suppression part of the first comparative antenna. [Figure 16]It is an explanatory diagram for explaining the reflection direction of the reflected wave reflected by the reflection suppression portions having different shapes related to the first comparison antenna. [Figure 17] It is an enlarged view corresponding to FIG. 4 of the second comparison antenna. [Figure 18] It is an explanatory diagram for explaining the relationship between the reflection suppression effect of the leakage suppression portion according to the first embodiment and the depth of the depression. [Figure 19] It is a diagram showing the signal intensity when the reflected wave from an object is received in a state where no obstacle is arranged around the third comparison antenna. [Figure 20] It is a diagram showing the signal intensity when an obstacle is arranged between the third comparison antenna and an object and the reflected wave from the object and the reflected wave from the obstacle are received. [Figure 21] It is a diagram showing the signal intensity when the reflected wave from an object is received in a state where no obstacle is arranged around the antenna device according to the first embodiment. [Figure 22] It is a diagram showing the signal intensity when an obstacle is arranged between the antenna device according to the first embodiment and an object and the reflected wave from the object and the reflected wave from the obstacle are received. [Figure 23] It is an enlarged view corresponding to FIG. 4 of the antenna device according to the first modification of the first embodiment. [Figure 24] It is an enlarged view corresponding to FIG. 4 of the antenna device according to the first modification of the first embodiment. [Figure 25] It is an enlarged view corresponding to FIG. 4 of the antenna device according to the first modification of the first embodiment. [Figure 26] It is a diagram corresponding to FIG. 3 of the antenna device according to the second modification of the first embodiment. [Figure 27] It is a diagram corresponding to FIG. 3 of the antenna device according to the second embodiment. [Figure 28] It is an enlarged view of the XXVIII portion of FIG. [Figure 29] It is an explanatory diagram for explaining the relationship between the reflection suppression effect of the leakage suppression portion according to the second embodiment and the depth of the depression. [Figure 30]This figure corresponds to Figure 28 of the antenna device according to the first modified example of the second embodiment. [Figure 31] This figure corresponds to Figure 28 of the antenna device according to a second modified example of the second embodiment. [Figure 32] This is an exploded perspective view of a part of the antenna device according to the third embodiment, viewed from one side in the stacking direction. [Figure 33] This is a diagram showing a portion of the XXXIII-XXXIII cross-section in Figure 32. [Figure 34] This figure shows the resonance pattern according to the third embodiment. [Figure 35] This figure shows the electric field distribution when the antenna device according to the third embodiment receives reflected waves from the bumper. [Figure 36] This figure shows a resonance pattern according to the first modified example of the third embodiment. [Figure 37] This figure shows a resonance pattern according to the first modified example of the third embodiment. [Figure 38] This figure shows a resonance pattern according to the first modified example of the third embodiment. [Figure 39] This figure shows a resonance pattern according to a second modified example of the third embodiment. [Figure 40] This figure shows a resonance pattern according to a second modified example of the third embodiment. [Modes for carrying out the invention]

[0010] Embodiments of this disclosure will be described below with reference to the drawings. In the following embodiments, parts that are the same as or equivalent to those described in the prior embodiments will be denoted by the same reference numerals, and their descriptions may be omitted. Also, if only a part of a component is described in an embodiment, the components described in the prior embodiments can be applied to the other parts of that component. The following embodiments can be partially combined with each other, even if not explicitly stated, as long as it does not impede the combination.

[0011] (First Embodiment) The antenna device 1 of this embodiment will be described with reference to Figures 1 to 22. The antenna device 1 transmits radio waves toward an object and receives the radio waves reflected by the object to obtain information about the object, such as the distance to the object, the position of the object, and the shape of the object. In this embodiment, an example will be described in which the antenna device 1 of this disclosure is applied to a vehicle and mounted inside a bumper (not shown) of the vehicle. As shown in Figures 1 to 3, the antenna device 1 is composed of a substrate 10, an MMIC 20, an antenna device 30, and the like. Note that the substrate 10 and MMIC 20 are not shown in Figures 1 and 2.

[0012] The substrate 10 is a printed circuit board in which multiple wiring patterns are formed using conductive materials such as metal foil. As shown in Figure 3, the substrate 10 has a first surface 11 on one side in the thickness direction and a second surface 12 on the other side in the thickness direction. In this embodiment, an MMIC 20 is mounted on the second surface 12 of the substrate 10. In addition, a through-hole 13 is formed on the substrate 10 at a position opposite to the MMIC 20, penetrating the substrate 10.

[0013] The MMIC20 is a semiconductor device that includes an input / output section for transmitting and receiving radio waves. The MMIC20 is a transmitting and receiving section provided in conjunction with the antenna device 1. In this embodiment, the operating frequency of the radio waves transmitted and received by the MMIC20 is set to a frequency band corresponding to millimeter waves (for example, 76.5 GHz). However, the operating frequency of the radio waves transmitted and received by the MMIC20 is not limited to a frequency corresponding to millimeter waves, and may be a frequency other than millimeter waves. MMIC is an abbreviation for Monolithic Microwave Integrated Circuit. The MMIC20 is provided on the substrate 10. Specifically, the MMIC20 is mounted on the second surface 12 of the substrate 10 at a position where a substrate through-hole 13 is formed.

[0014] The antenna device 30 is the antenna section that transmits radio waves transmitted and received by the MMIC 20. The antenna device 30 is composed of a structure having a laminated structure in which two conductive waveguide forming sections 31 and 32 are stacked in a predetermined direction. The two waveguide forming sections 31 and 32 are composed of a resin block which is a dielectric. Specifically, the two waveguide forming sections 31 and 32 are mainly composed of polyphenylene sulfide, i.e., PPS, and as shown in Figure 3, at least a part of the surface is covered with a conductive film 35 such as a metal film which has higher electrical conductivity than the resin.

[0015] In this embodiment, two waveguide forming sections 31 and 32 are mainly formed from polyphenylene sulfide with a dielectric constant of 3.8 and a dielectric loss tangent of 0.015. The specific configuration of the two waveguide forming sections 31 and 32 will be described later. The antenna device 30 is formed by bonding the two waveguide forming sections 31 and 32 together. Note that Figure 3 shows the state before the two waveguide forming sections 31 and 32 are bonded together in order to make the two waveguide forming sections 31 and 32 easier to understand.

[0016] The antenna device 30 is fixed to the substrate 10 in a position where the stacking direction D1 of the two waveguide forming sections 31 and 32 coincides with the thickness direction of the substrate 10. For example, the antenna device 30 is bonded to the substrate 10 by adhesive. In this embodiment, of the two waveguide forming sections 31 and 32, the one closer to the substrate 10 is referred to as the feeding side forming section 31, and the one further away from the substrate 10 is referred to as the antenna side forming section 32. The conductive film 35 covering the surface of the feeding side forming section 31 is referred to as the first conductive film 351, and the conductive film 35 covering the surface of the antenna side forming section 32 is referred to as the second conductive film 352. The feeding side forming section 31 corresponds to the second waveguide forming section, and the antenna side forming section 32 corresponds to the first waveguide forming section.

[0017] The antenna device 30 is stacked in the order of a feed-side forming section 31 and an antenna-side forming section 32, from one side to the other in the stacking direction D1. Therefore, of the feed-side forming section 31 and the antenna-side forming section 32 that are adjacent to each other in the stacking direction D1, the antenna-side forming section 32 corresponds to the first waveguide at one end in the stacking direction D1, and the feed-side forming section 31 corresponds to the second waveguide at the other end in the stacking direction D1.

[0018] As shown in Figures 1 and 2, the power supply side forming portion 31 and the antenna side forming portion 32 are thin plates and have the same rectangular shape in plan view along the stacking direction D1. Furthermore, the power supply side forming portion 31 and the antenna side forming portion 32 are approximately the same size in plan view so that they overlap each other in the stacking direction D1. Parts of the opposing surfaces of the power supply side forming portion 31 and the antenna side forming portion 32 are in contact. As a result, the power supply side forming portion 31 and the antenna side forming portion 32 are electrically connected.

[0019] The power supply side forming portion 31 has at least a portion of its surface covered with a first conductive film 351 made of gold, silver, copper, or a combination thereof. For example, in this embodiment, the entire surface of the power supply side forming portion 31 is covered with the first conductive film 351. The power supply side forming portion 31 has a power supply side waveguide forming surface 311 on one side in the stacking direction D1, and a substrate facing surface 312 on the other side in the stacking direction D1. The power supply side waveguide forming surface 311 of the power supply side forming portion 311 faces the antenna side forming portion 32 and is bonded to the antenna side forming portion 32.

[0020] Furthermore, the feeding side forming portion 31 has a substrate-facing surface 312 that faces the substrate 10 and is bonded to the first surface 11 of the substrate 10. The feeding side forming portion 31 faces the MMIC 20 via the substrate 10. The feeding side waveguide forming surface 311 is the surface on which the transmitting waveguide 33 and receiving waveguide 34, described later, are formed. Since the feeding side forming portion 31 and the antenna side forming portion 32 are electrically connected to each other, the antenna side forming portion 32 is electrically connected to the substrate 10 via the feeding side forming portion 31. The feeding side waveguide forming surface 311 corresponds to the second waveguide surface that is bonded to the antenna side forming portion 32.

[0021] Furthermore, as shown in Figure 2, the power supply side forming section 31 has four power supply sections 313 and four power receiving sections 314 formed therein, which are provided to allow radio waves to propagate between them and the MMIC 20. The four power supply sections 313 and four power receiving sections 314 are formed in the power supply side forming section 31 as through holes that penetrate the power supply side forming section 311 from the power supply side waveguide forming surface 311 to the substrate facing surface 312, and are provided to allow radio waves to propagate between them and the MMIC 20. The four power supply sections 313 and four power receiving sections 314 are formed in the power supply side forming section 31 at positions facing the MMIC 20, with the substrate through holes 13 in between. This allows radio waves to propagate between the power supply sections 313 and power receiving sections 314 and the MMIC 20.

[0022] Furthermore, as shown in Figures 1 and 3, the power supply side forming section 31 has four first transmitting grooves 315 and four first receiving grooves 316 formed on the power supply side waveguide forming surface 311. Each of the four first transmitting grooves 315, together with the second transmitting groove 323 of the antenna side forming section 32 (described later), forms a transmitting waveguide 33 through which radio waves propagate between it and the MMIC 20. Each of the four first receiving grooves 316, together with the second receiving groove 324 of the antenna side forming section 32 (described later), forms a receiving waveguide 34 through which radio waves propagate between it and the MMIC 20.

[0023] The four first transmitting grooves 315 and the four first receiving grooves 316 are composed of bottomed grooves that are recessed from one side to the other in the stacking direction D1, and are formed to extend in a direction intersecting the stacking direction D1 along the power supply side waveguide forming surface 311. Specifically, the four first transmitting grooves 315 and the four first receiving grooves 316 are formed to extend in a direction perpendicular to the stacking direction D1.

[0024] Here, the direction in which the four first transmitting grooves 315 and the four first receiving grooves 316 extend is defined as the waveguide extension direction D2, and the direction perpendicular to the stacking direction D1 and the waveguide extension direction D2 is defined as the waveguide alignment direction D3. The four first transmitting grooves 315 and the four first receiving grooves 316 are formed aligned at predetermined intervals in the waveguide alignment direction D3. Furthermore, the four first transmitting grooves 315 are formed on one side of the power supply side waveguide forming surface 311 in the waveguide extension direction D2. In contrast, the four first receiving grooves 316 are formed on the other side of the power supply side waveguide forming surface 311 in the waveguide extension direction D2. Note that the spacing of the four first transmitting grooves 315 in the waveguide alignment direction D3 is smaller than that of the four first receiving grooves 316.

[0025] Each of the four first transmitting grooves 315 has a power supply section 313 formed on its bottom surface. Specifically, the power supply section 313 is formed on the bottom surface of the other end of the first transmitting groove 315 in the waveguide extension direction D2. That is, the power supply section 313 is formed on the center side of the power supply side waveguide forming surface 311 of the first transmitting groove 315. Each of the four first receiving grooves 316 has a power receiving section 314 formed on its bottom surface. Specifically, the power receiving section 314 is formed on the bottom surface of one end of the first receiving groove 316 in the waveguide extension direction D2. That is, the power receiving section 314 is formed on the center side of the power supply side waveguide forming surface 311 of the first receiving groove 316.

[0026] The antenna-side forming portion 32 has a second conductive film 352 made of gold, silver, copper, or a combination thereof, on a portion of its surface. The antenna-side forming portion 32 has an antenna surface 321 on one side in the stacking direction D1 and an antenna-side waveguide forming surface 322 on the other side in the stacking direction D1. The antenna surface 321 of the antenna-side forming portion 32 is formed in a planar shape facing the external space, and the antenna surface 321 is capable of transmitting millimeter waves, which are radio waves, toward objects in the external space, and receiving millimeter waves, which are radio waves, reflected by objects. In other words, the antenna surface 321 is a surface that transmits radio waves propagating from the MMIC 20 toward the external space and receives reflected waves propagating to the MMIC 20.

[0027] Furthermore, the antenna-side forming section 32 has an antenna-side waveguide forming surface 322 that faces the feed-side forming section 31 and is bonded to the feed-side forming section 31. The antenna-side waveguide forming surface 322 is the surface facing the feed-side waveguide forming surface 311 of the feed-side forming section 31, and is the surface on which the transmitting waveguide 33 and receiving waveguide 34, described later, are formed. The antenna-side waveguide forming surface 322 corresponds to the first waveguide surface that is bonded to the feed-side forming section 31.

[0028] As shown in Figures 2 and 3, the antenna-side forming section 32 has four second transmitting grooves 323, four second receiving grooves 324, and a leakage suppression section 40 formed on the antenna-side waveguide forming surface 322. Each of the four second transmitting grooves 323 is formed in a position opposite to any of the four first transmitting grooves 315 of the feeding-side forming section 31, and together with the first transmitting grooves 315, forms a transmitting waveguide 33 through which radio waves propagate between it and the MMIC 20. Each of the four second receiving grooves 324 is formed in a position opposite to any of the four first receiving grooves 316 of the feeding-side forming section 31, and together with the first receiving grooves 316, forms a receiving waveguide 34 through which radio waves propagate between it and the MMIC 20.

[0029] The four second transmitting grooves 323 and the four second receiving grooves 324 are composed of bottomed grooves that are recessed from one side to the other in the stacking direction D1, and are formed extending in the waveguide extension direction D2 along the antenna side waveguide forming surface 322. The four second transmitting grooves 323 and the four second receiving grooves 324 are also formed side by side at predetermined intervals in the waveguide alignment direction D3. The four second transmitting grooves 323 are formed on one side of the antenna side waveguide forming surface 322 in the waveguide extension direction D2. In contrast, the four second receiving grooves 324 are formed on the other side of the antenna side waveguide forming surface 322 in the waveguide extension direction D2.

[0030] The second transmitting groove 323, formed in this manner, forms a transmitting waveguide 33 with the first transmitting groove 315 when the feed-side forming portion 31 and the antenna-side forming portion 32 are bonded together. The transmitting waveguide 33 receives radio waves from the MMIC 20 via the feed portion 313. The second receiving groove 324, formed together with the first receiving groove 316 when the feed-side forming portion 31 and the antenna-side forming portion 32 are bonded together. The receiving waveguide 34 guides reflected waves reflected by an object to the MMIC 20 via the receiving portion 314.

[0031] Each of the four second transmitting grooves 323 has four output sections 325 formed on its bottom surface for emitting radio waves. Specifically, the output sections 325 are formed on the bottom surface of one end of the second transmitting groove 323 in the waveguide extension direction D2. That is, the output sections 325 are formed on the side of the second transmitting groove 323 closer to the end than the center of the feeding side waveguide forming surface 311. Each of the four second receiving grooves 324 has four receiving sections 326 formed on its bottom surface for receiving radio waves. Specifically, the receiving sections 326 are formed on the bottom surface of the other end of the second receiving groove 324 in the waveguide extension direction D2. That is, the receiving sections 326 are formed on the side of the second receiving groove 324 closer to the end than the center of the feeding side waveguide forming surface 311.

[0032] Each of the four output units 325 has multiple transmitting antenna slots 3251 formed through the antenna-side forming unit 32, as shown in Figure 3. Similarly, each of the four receiving units 326, although not shown, also has multiple receiving antenna slots formed through the antenna-side forming unit 32, similar to the output units 325. This allows the antenna device 30 to transmit radio waves propagated from the MMIC 20 to the transmitting waveguide 33 via the transmitting antenna slots 3251. Furthermore, the antenna device 30 can propagate radio waves received from the receiving antenna slots to the MMIC 20 via the receiving waveguide 34.

[0033] Furthermore, as shown in Figures 2 and 3, a leakage suppression section 40 is formed on a part of the antenna-side waveguide forming surface 322. Specifically, the leakage suppression section 40 is formed on the antenna-side waveguide forming surface 322, which is one of the surfaces of the feed-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 that form the transmit waveguide 33 and the receive waveguide 34. More specifically, the leakage suppression section 40 is formed in the portion of the antenna-side waveguide forming surface 322 where the second transmit groove 323 and the second receive groove 324 are not formed. The leakage suppression section 40 is formed in the portion of the antenna-side waveguide forming surface 322 excluding the portion where the second transmit groove 323 and the second receive groove 324 are formed, excluding the ends in the waveguide extension direction D2 and the waveguide alignment direction D3.

[0034] As shown in Figure 3, the leakage suppression section 40 is composed of a plurality of antenna-side recesses 41 formed by a portion of the antenna-side waveguide forming surface 322 that is recessed from the other side toward the one side in the stacking direction D1. That is, the portion of the leakage suppression section 40 in which the antenna-side recesses 41 are not formed is formed in an uneven shape that protrudes to the other side in the stacking direction D1 compared to the portion in which the antenna-side recesses 41 are formed. The leakage suppression section 40 configured in this way is composed of a second conductive film 352 in which the other side in the stacking direction D1 is formed in an uneven shape. The antenna-side recesses 41 correspond to leakage recesses that are formed in the stacking direction D1.

[0035] The antenna-side recess 41 is approximately square in shape when viewed along the stacking direction D1. The space formed by the antenna-side recess 41 is rectangular in shape. Multiple antenna-side recesses 41 are formed at predetermined intervals along the waveguide extension direction D2 and the waveguide alignment direction D3. In Figure 3, for convenience, a representative reference is given to each of the multiple antenna-side recesses 41, while the references for others are omitted.

[0036] The spacing in the waveguide extension direction D2 and the waveguide alignment direction D3 of the antenna-side recess 41 are equal to each other. Here, the spacing in the waveguide extension direction D2 of the antenna-side recess 41 is called the first recess spacing L1, and the spacing in the waveguide alignment direction D3 of the antenna-side recess 41 is called the second recess spacing L2. The first recess spacing L1 and the second recess spacing L2 are set based on the wavelength of the millimeter waves transmitted by the MMIC 20. When the wavelength of the millimeter waves is λ, the first recess spacing L1 and the second recess spacing L2 are 0.5λ, that is, half the size of the wavelength of the millimeter waves. In this embodiment, where the frequency of the millimeter waves transmitted by the MMIC 20 is 76.5 GHz, the first recess spacing L1 and the second recess spacing L2 are set to approximately 1.95 mm. Furthermore, the first and second recess spacings L1 and L2 are not limited to 0.5λ, but may be set to a value greater than or less than 0.5λ. Also, the first and second recess spacings L1 and L2 may be set to different values ​​from each other. In this case, it is more preferable to set the first and second recess spacings L1 and L2 to values ​​obtained by multiplying 1 / 4λ by an integer, such as 0.25λ and 0.75λ.

[0037] The reason for providing the unevenly shaped leakage suppression portion 40 on the antenna-side waveguide forming surface 322 that forms the transmitting waveguide 33 and the receiving waveguide 34 will now be explained. When the feeding-side forming portion 31 and the antenna-side forming portion 32 are joined by adhesive to form the transmitting waveguide 33 and the receiving waveguide 34, there is a risk that a gap will occur between the feeding-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322. If a gap occurs between the feeding-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322, there is a risk that radio waves propagated between the feeding-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 will propagate into the outside space. Therefore, the gap between the feeding-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 is a cause of radio wave leakage from the antenna device 30.

[0038] In contrast, by providing a leakage suppression section 40 on the antenna-side waveguide forming surface 322, radio waves propagated between the power supply-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 are guided to the antenna-side recess 41, thereby attenuating the radio waves propagated in the gap. Therefore, leakage of radio waves from the antenna device 30 caused by the gap between the power supply-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 can be suppressed.

[0039] Incidentally, the effect of suppressing radio wave leakage differs depending on the size of the stacking direction D1 of the antenna-side recess 41, that is, the depth of the antenna-side recess 41. In other words, the amount of radio wave attenuation when the leakage suppression section 40 attenuates radio waves propagated in the gap changes depending on the depth of the antenna-side recess 41. The difference in the effect of suppressing radio wave leakage that changes depending on the depth of the antenna-side recess 41 will be explained with reference to Figure 5. Hereinafter, the depth of the antenna-side recess 41 will be referred to as the recess depth H. As shown in Figure 5, the effect of suppressing radio wave leakage changes periodically with respect to the recess depth H. The period of the periodically changing effect of suppressing radio wave leakage corresponds to the wavelength of the millimeter waves transmitted by the MMIC 20.

[0040] Specifically, the radio wave leakage suppression effect changes approximately with a period of 1 / 2λ, where λ is the wavelength of the millimeter wave, multiplied by 0.5. The maximum and minimum values ​​alternate at intervals of approximately 1 / 4λ. As shown in Figure 5, the radio wave leakage suppression effect tends to be increased when the recess depth H is set to an odd number multiplied by 1 / 4λ, such as 0.25λ or 0.75λ. Conversely, the radio wave leakage suppression effect tends to decrease when the recess depth H is set to an even number multiplied by 1 / 4λ, such as 0.5λ.

[0041] Therefore, the depth H of each of the multiple antenna-side recesses 41 is set based on the wavelength of the millimeter waves transmitted by the MMIC 20, in order to maximize the effect of suppressing radio wave leakage. In this embodiment, the recess depth H is set to 0.25λ, which is 1 multiplied by 1, or approximately 0.98 mm. The reason why the recess depth H is set to 0.25λ, which is 1 multiplied by 1, rather than 0.75λ, which is 3 multiplied by 1, or approximately 2.94 mm, will be explained later.

[0042] Furthermore, as shown in Figures 1 and 3, a portion of the antenna surface 321 is not covered by the second conductive film 352, such as a metal film, and as a result, the resin in the portion not covered by the second conductive film 352 is exposed to the outside space. In other words, in this embodiment, where the portion of the antenna-side forming part 32 excluding the second conductive film 352 is made of polyphenylene sulfide, a portion of the antenna surface 321 is made of resin. In Figure 1, the portion where the resin is exposed is indicated by hatching with diagonal lines for clarity. Hereinafter, the portion of the antenna surface 321 where the resin is exposed will be referred to as the resin exposed portion 3211.

[0043] The exposed resin portion 3211 is formed on a part of the antenna surface 321. Specifically, the exposed resin portion 3211 is formed on the antenna surface 321 in a portion that overlaps with the portion of the antenna-side waveguide forming surface 322 where the leakage suppression portion 40 is formed, in the stacking direction D1. That is, the exposed resin portion 3211 is formed on the antenna surface 321 in a portion that overlaps with the portion of the antenna-side waveguide forming surface 322 where the second transmitting groove portion 323 and the second receiving groove portion 324 are not formed, in the stacking direction D1. In this embodiment in which the leakage suppression portion 40 is formed in this way, the portion of the antenna surface 321 that overlaps with the second transmitting groove portion 323 and the second receiving groove portion 324 in the stacking direction D1 is covered with the second conductive film 352. Furthermore, the portion of the antenna surface 321 where the output portion 325 and the receiving portion 326 are not formed is formed in a substantially planar shape.

[0044] The resin exposed portion 3211 can be formed by applying a masking treatment to the area where the resin exposed portion 3211 is to be formed when forming the second conductive film 352 on the antenna surface 321, thereby preventing the second conductive film 352 from being formed on the masked area. Alternatively, the resin exposed portion 3211 may be formed on the antenna surface 321 by forming the second conductive film 352 over the entire antenna surface 321, and then removing the second conductive film 352 from the area where the resin exposed portion 3211 is to be formed by laser processing or the like.

[0045] In the antenna device 1 configured in this way, when transmitting millimeter waves toward an object, the millimeter waves generated by the MMIC 20 propagate from the feed unit 313 to the transmitting waveguide 33 and are transmitted to the outside space from the transmitting antenna slot 3251 of the output unit 325. The millimeter waves transmitted from the transmitting antenna slot 3251 are then transmitted toward the object to be detected. The millimeter waves reflected by the object are received by the receiving antenna slot of the receiving unit 326. The millimeter waves received by the receiving unit 326 pass through the receiving waveguide 34 and are input to the MMIC 20 from the power receiving unit 314. Based on the signal input to the MMIC 20, the antenna device 1 acquires information about the object, such as the distance to the object, the position of the object, and the shape of the object.

[0046] Incidentally, when the antenna device 1 is mounted inside the vehicle's bumper, the bumper is located in the path through which the millimeter waves transmitted from the antenna device 1 pass. Here, the dielectric constant of the air through which the millimeter waves pass and the dielectric constant of the bumper, which is generally made of resin, differ relatively significantly. For this reason, some of the millimeter waves transmitted from the antenna device 1 may be reflected by the surface of the bumper, where the dielectric constant changes sharply along the path through which they pass.

[0047] Then, a portion of the reflected wave reflected by the bumper propagates to the antenna surface 321 of the antenna device 1. If the dielectric constant of air and the dielectric constant of the antenna surface 321 are significantly different, a portion of the reflected wave reflected by the bumper may also be reflected by the antenna surface 321. Furthermore, a portion of the reflected wave reflected by the antenna surface 321 may be reflected again by the bumper, and then a portion of that reflected wave may be reflected by the antenna surface 321 again. As a result, there is a risk of multiple reflections occurring between the antenna surface 321 and the bumper, where the millimeter waves transmitted from the antenna device 1 are repeatedly reflected.

[0048] In this case, the antenna device 1 will receive multiple reflected waves generated between the antenna surface 321 and the bumper. As a result, the antenna device 1 will receive a reflected wave in which the reflected wave reflected by the object and the multiple reflected wave are superimposed. However, when the reflected wave reflected by the object and the multiple reflected wave superimposed, the amplitude of the reflected wave reflected by the object increases or decreases depending on the phase of the multiple reflected wave. This increase or decrease in the amplitude of the reflected wave reflected by the object disrupts the directivity of the reflected wave from the object received by the antenna device 1, and becomes a source of errors when the antenna device 1 acquires the distance to the object, the position of the object, the shape of the object, etc. For this reason, it is desirable that the antenna device 1 be configured in a way that makes it difficult for multiple reflections to occur between the antenna surface 321 and the bumper.

[0049] Here, in describing the configuration of the antenna device 1 of this embodiment, we will describe the first comparative antenna 100 shown in Figures 6 to 8, which is a first comparative example of the antenna device 1. The first comparative antenna 100 has a configuration that makes it difficult for multiple reflections to occur between the first comparative antenna 100 and the bumper. The configuration of the first comparative surface 110, which corresponds to the antenna surface 321 of the antenna device 1 of this embodiment, differs from that of the antenna device 1 of this embodiment. Specifically, as shown in Figures 6 and 8, the first comparative antenna 100 differs from the antenna device 1 of this embodiment in that a reflection suppression part 120 is provided in the part that forms the resin exposed part 3211 to make it difficult for reflected waves from the bumper to be reflected. Note that, as shown in Figures 6 and 7, the antenna device 1 and the first comparative antenna 100 of this embodiment have the same configuration as the antenna device 1 of this embodiment.

[0050] As shown in Figures 6 and 8, a reflection suppression portion 120 is formed on a part of the first comparison surface 110 to suppress reflection on the first comparison surface 110. The reflection suppression portion 120 is covered on the first comparison surface 110 by a second conductive film 352 made of metal, similar to other parts. Furthermore, as shown in Figures 8 and 9, the reflection suppression portion 120 is composed of a plurality of reflection suppression recesses 121 that are recessed from one side to the other in the stacking direction D1 on a part of the first comparison surface 110. That is, the reflection suppression portion 120 is formed in an uneven shape in which the parts where reflection suppression recesses 121 are not formed protrude to one side in the stacking direction D1 compared to the parts where reflection suppression recesses 121 are formed.

[0051] The reflection-suppressing recess 121 is approximately square in shape when viewed along the stacking direction D1. The space formed by the reflection-suppressing recess 121 is rectangular in shape. Multiple reflection-suppressing recesses 121 are formed at predetermined intervals along the waveguide extension direction D2 and the waveguide alignment direction D3. In Figures 8 and 9, for convenience, a representative reference is given to each of the multiple reflection-suppressing recesses 121, while the references for others are omitted.

[0052] The spacing between the reflection suppression recesses 121 in the waveguide extension direction D2 and the waveguide alignment direction D3 is equal to each other. Furthermore, the spacing between the reflection suppression recesses 121 in the waveguide extension direction D2 and the waveguide alignment direction D3 is set based on the wavelength of the millimeter waves transmitted by the MMIC 20. Specifically, as shown in Figure 10, the spacing between the reflection suppression recesses 121 in the waveguide extension direction D2 and the waveguide alignment direction D3 is 0.5λ, that is, half the wavelength of the millimeter waves. When the frequency of the millimeter waves transmitted by the MMIC 20 is 76.5 GHz, the spacing between the reflection suppression recesses 121 in the waveguide extension direction D2 and the waveguide alignment direction D3 is set to approximately 1.95 mm.

[0053] Furthermore, as shown in Figure 10, the dimensions of the reflection suppression recess 121 in the waveguide extension direction D2 and the waveguide alignment direction D3, as well as the dimensions of the reflection suppression recess 121 in the stacking direction D1, are set based on the wavelength of the millimeter waves transmitted by the MMIC 20. Specifically, the dimensions of the reflection suppression recess 121 in the waveguide extension direction D2 and the waveguide alignment direction D3 are set to 0.65λ, or approximately 2.54 mm. The depth of the reflection suppression recess 121 is set to 0.75λ, or approximately 2.94 mm.

[0054] The reason why the reflection suppression section 120 is composed of a reflection suppression recess 121 is explained below. When the reflected wave reflected by the bumper propagates to the first comparison surface 110 of the first comparison antenna 100, this reflected wave is reflected by the first comparison surface 110 which is covered with the second conductive film 352.

[0055] When reflected waves propagate across the first comparison surface 110, the reflected waves reflected at the location where the reflection suppression recess 121 is formed and the reflected waves reflected at the location where the reflection suppression recess 121 is not formed have opposite phases to each other. As a result, these two reflected waves cancel each other out and are attenuated. Therefore, the first comparison antenna 100 can suppress the effects of multiple reflected waves.

[0056] Furthermore, when a reflected wave propagates to the first comparison surface 110, the reflected wave propagated to the area where the reflection suppression recess 121 is formed is scattered by the space within the reflection suppression recess 121. By scattering the reflected wave, the reflected wave incident on the first comparison surface 110 is scattered in a direction different from the direction of incidence, thereby suppressing the generation of multiple reflected waves.

[0057] The scattering of reflected waves by the reflection suppression unit 120 will be explained with reference to Figure 11. Here, in Figure 11, the angle of incidence when a reflected wave is incident in a direction perpendicular to the first comparison surface 110 is set to 0°. With the reflection suppression unit 120 configured as described above, as shown in Figure 11, the reflected wave incident on the first comparison surface 110 can be scattered around +60° and -60°. As a result, the signal strength of the multiple reflected waves received by the first comparison antenna 100 is attenuated, and the effect of the multiple reflected waves can be suppressed.

[0058] Furthermore, when the reflection suppression unit 120 attenuates the signal strength of multiple reflected waves, as shown in Figure 12, the amount of signal strength attenuation changes periodically according to the depth of the reflection suppression recess 121. The periodically changing amount of signal strength attenuation corresponds to the wavelength of the millimeter waves transmitted by the MMIC 20. Specifically, the amount of signal strength attenuation changes with a period of approximately 1 / 2λ, which is obtained by multiplying the wavelength of the millimeter wave, λ, by 0.5, and the maximum and minimum values ​​alternate at intervals of approximately 1 / 4λ. For this reason, as shown in Figure 12, when the depth of the reflection suppression recess 121 is set to a value that is an odd number multiplied by 1 / 4λ, such as 0.25λ or 0.75λ, the amount of signal strength attenuation tends to be larger. Conversely, when the depth of the reflection suppression recess 121 is set to a value that is an even number multiplied by 1 / 4λ, such as 0.5λ, the amount of attenuation tends to be smaller.

[0059] However, in the reflection suppression unit 120 with the above configuration, the effect of attenuating the signal intensity of multiple reflected waves differs depending on the angle of incidence of the reflected wave incident on the first comparison surface 110. According to the inventors' studies, when the depth of the reflection suppression recess 121 is 0.25λ, the signal intensity attenuation is as shown in Figure 12 if the angle of incidence when the reflected wave is incident is within the range of -10° to +10°. However, if the angle of incidence when the reflected wave is incident is less than -10° or greater than +10°, the signal intensity attenuation becomes smaller than the attenuation shown in Figure 12. In other words, when the depth of the reflection suppression recess 121 is set to 0.25λ, the multiple reflection suppression effect of the reflection suppression unit 120 is small.

[0060] In contrast, when the depth of the reflection suppression recess 121 is 0.75λ, the signal intensity attenuation is as shown in Figure 12 for incident angles in the range of -60° to +60° when the reflected wave is incident. That is, when the depth of the reflection suppression recess 121 is set to 0.75λ, the multiple reflection suppression effect of the reflection suppression section 120 is greater while accommodating a wider incident angle of the reflected wave compared to when the depth of the reflection suppression recess 121 is set to 0.25λ. For this reason, in the first comparison antenna 100, the depth of the reflection suppression recess 121 is set to 0.75λ, not 0.25λ. However, when the depth of the reflection suppression recess 121 is set to 0.75λ, which is approximately 2.94 mm, it is necessary to increase the size of the stacking direction D1 of the first comparison antenna 100 compared to when the depth of the reflection suppression recess 121 is set to 0.25λ, which is 0.98 mm.

[0061] Furthermore, suppose the bumper that reflects millimeter waves toward the first comparison antenna 100 is bent in the direction of the first comparison antenna 100. In this case, even if the reflection suppression unit 120 reflects the reflected wave in a direction different from the incident direction, there is a risk that the reflected wave cannot be scattered between the bent bumper and the first comparison surface 110.

[0062] According to the inventors' investigation, even if the reflection suppression section 120, which is covered with a second conductive film 352 made of metal, reflects the reflected wave in a direction different from the direction of incidence, if the reflected wave cannot be scattered, the signal intensity of the reflected wave may not be attenuated at all. For this reason, it was found that when the bumper that reflects millimeter waves is bent, even if the reflection suppression section 120 reflects the reflected wave in a direction inclined from the direction of incidence, it may be difficult to suppress the effects of multiple reflected waves with the reflection suppression section 120 covered with the second conductive film 352.

[0063] As explained above, in the method using a reflection suppression section 120 composed of a reflection suppression recess 121 covered with a second conductive film 352 made of metal, it is difficult to miniaturize the first comparison antenna 100, and furthermore, it may be difficult to suppress the effects of multiple reflected waves.

[0064] In the above description, a comparative example was presented in which the reflection suppression section 120 is composed of multiple reflection suppression recesses 121. However, according to the inventors' investigation, similar results were obtained even when the shape of the reflection suppression section 120 was different, as shown in Figures 13 and 15.

[0065] For example, as shown in Figure 13, suppose the reflection suppression section 120 is composed of a plurality of reflection suppression grooves 122 formed along the first comparison surface 110. The reflection suppression grooves 122 are formed by recessing a portion of the first comparison surface 110 from one side to the other in the stacking direction D1. The plurality of reflection suppression grooves 122 are formed at intervals of 0.7λ, or approximately 2.74 mm, in the waveguide extension direction D2. The size of the reflection suppression grooves 122 in the waveguide extension direction D2 is set to 0.5λ, or approximately 1.96 mm. The size of the reflection suppression grooves 122 in the stacking direction D1 is set to 0.7λ, or approximately 2.74 mm.

[0066] Even with this shape, as shown in Figure 14, the reflection suppression section 120 can scatter the reflected waves incident on the first comparison surface 110 to around +60° and -60°. Therefore, the signal strength of the reflected waves received by the first comparison surface 110 from the 0° direction can be attenuated, thereby suppressing the effects of multiple reflected waves. However, since the size of the stacking direction D1 of the reflection suppression groove section 122 is 0.7λ, it is difficult to miniaturize the first comparison antenna 100. Also, if the bumper is bent, it may be difficult to scatter the reflected waves between the bent bumper and the first comparison surface 110, making it difficult to suppress the effects of multiple reflected waves.

[0067] Furthermore, as shown in Figure 15, the multiple reflection suppression grooves 122 formed along the first comparison surface 110 are formed extending in directions intersecting the waveguide extension direction D2 and the waveguide alignment direction D3. The multiple reflection suppression grooves 122 are formed at intervals of 0.55λ, or approximately 2.16 mm, in the waveguide extension direction D2. The size of the reflection suppression grooves 122 in the waveguide extension direction D2 is set to 0.5λ, or approximately 1.96 mm. The size of the reflection suppression grooves 122 in the stacking direction D1 is set to 0.7λ, or approximately 2.74 mm. When the reflection suppression section 120 has this shape, as shown in Figure 16, it is difficult for the reflection suppression section 120 to scatter reflected waves incident on the first comparison surface 110. For this reason, it is difficult for the reflection suppression section 120 to suppress the effects of multiple reflected waves.

[0068] Therefore, the inventors considered a method to suppress the effects of multiple reflected waves by passing the reflected waves, which are lost through heat exchange, rather than scattering the reflected waves reflected by the bumper at the antenna surface 321. The method of losing the energy of reflected waves using a dielectric will be explained with reference to the second comparative antenna 200 shown in Figure 17, which is a second comparative example of the antenna device 1 of this embodiment.

[0069] The second comparison antenna 200 differs from the antenna device 1 in that a dielectric member 220 made of a dielectric material is arranged on the second comparison surface 210, which corresponds to the antenna surface 321 of the antenna device 1 in this embodiment. The dielectric member 220 is made of polyphenylene sulfide, for example, the same material as the antenna side forming part 32, and its surface and interior are composed of dielectric material. Furthermore, the dielectric member 220 is provided in the area that forms the resin exposed part 3211 in the antenna device 1 of this embodiment. Specifically, the dielectric member 220 is arranged on the second comparison surface 210 in the area where the output part 325 and the receiving part 326 are not formed.

[0070] In this way, by providing a dielectric member 220 made of dielectric material on the second comparison surface 210, the reflected waves reflected by the bumper can be passed inside the dielectric member 220, and the energy of the reflected waves can be lost through heat exchange. As a result, the reflected waves from the bumper are less likely to be reflected by the second comparison surface 210, and the generation of multiple reflected waves, in which millimeter waves are repeatedly reflected between the bumper and the second comparison surface 210, can be suppressed.

[0071] Furthermore, by using the dielectric member 220 to reduce the energy of the reflected wave, the energy of the reflected wave can be reduced even if the direction of incidence of the reflected wave incident on the second comparison surface 210 from the bumper intersects with the second comparison surface 210. Therefore, even when the bumper is bent, the generation of multiple reflected waves can be suppressed.

[0072] However, the method of providing the dielectric member 220 on the second comparison surface 210 increases the size of the stacking direction D1 of the second comparison antenna 200. In addition, the method of providing the dielectric member 220 on the second comparison surface 210 involves adding the dielectric member 220 as a component to suppress the effects of multiple reflected waves, which increases manufacturing costs compared to the configuration without the dielectric member 220.

[0073] Therefore, through further investigation, the inventors considered a method to suppress the effects of multiple reflected waves by propagating the reflected waves from the bumper into the dielectric antenna-side forming portion 32 and losing the energy of the reflected waves, rather than adding a dielectric member 220. Furthermore, while the reflected waves propagated into the antenna-side forming portion 32 are reflected by the second conductive film 352 within the antenna-side forming portion 32, the inventors considered a method to suppress the effects of multiple reflected waves by changing the phase of some of the reflected waves reflected within the antenna-side forming portion 32.

[0074] In this embodiment, the antenna device 1 has a portion of the antenna surface 321 of the antenna side forming portion 32 that is not covered by the second conductive film 352 and is composed of a resin exposed portion 3211. Specifically, in the antenna device 1, the portion of the antenna surface 321 that overlaps with the portion where the leakage suppression portion 40 is formed in the stacking direction D1 is composed of a resin exposed portion 3211.

[0075] In the antenna device 1 configured in this way, when reflected waves from the bumper propagate to the antenna surface 321, the portion of the antenna surface 3211 composed of the resin exposed portion 3211 is less likely to reflect the waves compared to the portion covered by the second conductive film 352. Therefore, when reflected waves from the bumper propagate to the resin exposed portion 3211, most of these reflected waves propagate from the resin exposed portion 3211 into the antenna-side forming portion 32. The reflected waves propagated into the antenna-side forming portion 32 then lose energy through heat exchange as they pass through the resin-containing antenna-side forming portion 32. Consequently, since reflected waves from the bumper are less likely to be reflected by the antenna surface 321, the effects of multiple reflected waves, where millimeter waves are repeatedly reflected between the bumper and the antenna surface 321, can be suppressed.

[0076] Incidentally, in this embodiment, the antenna device 1 has a leakage suppression section 40 formed on the other side of the antenna side forming section 32 in the stacking direction D1, which suppresses radio wave leakage when a gap occurs between the power supply side waveguide forming surface 311 and the antenna side waveguide forming surface 322. This leakage suppression section 40 is formed in the area that overlaps with the resin exposed section 3211 in the stacking direction D1. The leakage suppression section 40 is composed of a plurality of antenna side recesses 41 that are recessed from the other side toward the one side in the stacking direction D1, and is formed in an uneven shape. Furthermore, the recess depth H, which is the size of the antenna side recesses 41 in the stacking direction D1, is set to 0.25λ, which is the size obtained by multiplying the wavelength of the millimeter waves transmitted by the MMIC 20 by 0.25, in order to improve the effect of suppressing radio wave leakage.

[0077] Then, the reflected wave propagates from the resin exposed portion 3211 into the antenna-side forming portion 32 and passes through the antenna-side forming portion 32, propagating from one side in the lamination direction D1 to the other side of the antenna-side forming portion 32, and is reflected by the surface of the second conductive film 352 that forms the leakage suppression portion 40 on one side in the lamination direction D1. Specifically, the reflected wave that has passed through the antenna-side forming portion 32 is reflected by the surface of the second conductive film 352 that constitutes the antenna-side waveguide forming surface 322, on one side in the lamination direction D1 where the antenna-side recess portion 41 is formed, and on the surface of the part of the second conductive film 352 that does not form the antenna-side recess portion 41.

[0078] Here, since the recess depth H is set to 0.25λ, the reflected waves reflected at the portion of the second conductive film 352 that forms the antenna-side recess 41 and the reflected waves reflected at the portion that does not form the antenna-side recess 41 have opposite phases to each other. Therefore, the reflected waves reflected at the portion that forms the antenna-side recess 41 and the reflected waves reflected at the portion that does not form the antenna-side recess 41 cancel each other out and are attenuated. Accordingly, the antenna device 1 of this embodiment can also suppress the generation of multiple reflected waves by the leakage suppression unit 40 that suppresses radio wave leakage when a gap occurs between the feed-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322.

[0079] Here, the amount of signal intensity attenuation when the signal intensity of the reflected wave propagated to the antenna-side forming section 32 is attenuated by the leakage suppression section 40 of this embodiment will be explained with reference to Figure 18. The solid line in Figure 18 shows the amount of signal intensity attenuation of the reflected wave from the bumper attenuated by the leakage suppression section 40 of the antenna device 1 of this embodiment. In addition, in Figure 18, in order to compare the suppression of reflected waves by the leakage suppression section 40 and the reflection suppression section 120 of the first comparison antenna 100, the amount of signal intensity attenuated from the bumper attenuated by the reflection suppression section 120 of the first comparison antenna 100 is shown by a dashed line.

[0080] As shown in Figure 18, when the signal intensity of the reflected wave from the bumper is attenuated by the leakage suppression unit 40, the amount of attenuation changes periodically according to the depth H of the recess, similar to how the amount of attenuation when attenuated by the reflection suppression unit 120 changes periodically according to the depth of the reflection suppression recess 121. However, the correlation between the reflection suppression effect of the leakage suppression unit 40 and the recess depth H is different from the correlation between the reflection suppression effect of the reflection suppression unit 120 and the depth of the reflection suppression recess 121.

[0081] Specifically, when the leakage suppression unit 40 attenuates the reflected wave, the amount of attenuation changes with a period of approximately 1 / 5λ, which is the wavelength λ of the millimeter wave transmitted by the MMIC 20 multiplied by 0.2, and the maximum and minimum values ​​alternate at intervals of approximately 1 / 10λ. For this reason, the period of the signal intensity attenuation amount attenuated by the leakage suppression unit 40 is shorter than the period of the signal intensity attenuation amount attenuated by the reflection suppression unit 120. In the above-described configuration of the leakage suppression unit 40 and the reflection suppression unit 120, as shown in Figure 18, the period of the signal intensity attenuation amount attenuated by the leakage suppression unit 40 is less than or equal to 1 / 2 of the period of the signal intensity attenuated by the reflection suppression unit 120.

[0082] The reason why the period of the signal intensity becomes shorter when the signal is attenuated by the leakage suppression section 40 is explained below. When the reflected wave is attenuated by the leakage suppression section 40, the reflected wave passes through the antenna-side forming section 32, which is made of polyphenylene sulfide resin. The antenna-side forming section 32, which is made of resin, has a significantly higher dielectric constant than air. Therefore, the reflected wave from the bumper propagates through the antenna-side forming section 32, and its wavelength is shortened compared to before it propagated through the antenna-side forming section 32.

[0083] In contrast, when the reflected wave is scattered and the signal strength is attenuated by the reflection suppression unit 120, the reflected wave passes through the air without passing through the antenna-side forming unit 32 and is attenuated by the reflection suppression unit 120, so it does not change much from the wavelength after being reflected by the bumper. From the above, the period of the signal strength attenuation amount attenuated by the leakage suppression unit 40 is shorter than the period of the signal strength attenuation amount attenuated by the reflection suppression unit 120.

[0084] According to the inventors' studies, as shown in Figure 18, the signal intensity attenuated by the leakage suppression unit 40 is easily attenuated when the recess depth H is slightly less than 0.1λ, slightly less than 0.25λ, and slightly greater than 0.4λ. Of these three recess depths H, the size slightly less than 0.25λ corresponds to 0.75λ, which is the depth of the reflection suppression recess 121 where the reflection suppression effect is easily increased when the reflection suppression unit 120 attenuates the reflected wave.

[0085] In other words, when the recess depth H is set to 0.25λ, it is easier to suppress multiple reflections because the signal strength of the reflected wave from the bumper can be kept relatively low while accommodating a wide angle of incidence of the reflected wave. For this reason, by setting the recess depth H to approximately 0.25λ, it is possible to achieve both attenuation of the signal strength of the reflected wave at various angles of incidence to the antenna surface 321 and suppression of radio wave leakage from the gap between the feed side waveguide forming surface 311 and the antenna side waveguide forming surface 322.

[0086] Furthermore, with a configuration in which the signal intensity of the reflected wave is attenuated by the leakage suppression section 40, there is no need to add components such as dielectrics to the antenna surface 321, and it is also possible to avoid increasing the size of the antenna device 1 in the stacking direction D1. In addition, since there is no need to provide an uneven structure to suppress reflection on the antenna surface 321 side, the manufacturing cost of the antenna device 1 can be reduced.

[0087] Next, the effects of installing the antenna device 1 of this embodiment on a vehicle will be explained with reference to Figures 19 to 22. Figures 19 and 20 show the signal strength when a third comparative antenna 300, which does not have a reflection suppression unit 120 compared to the first comparative antenna 100, receives reflected waves, as is the case for a third comparative antenna 1 of this embodiment. Specifically, Figure 19 shows the signal strengths of four devices when millimeter waves are transmitted from each of the four output units 325 toward an object without placing any objects that reflect reflected waves, such as bumpers that reflect millimeter waves, around the third comparative antenna 300, and the reflected waves from the object are received by each of the four receiving units 326. Figure 20 shows the signal strengths of four devices when an obstacle OB, simulating a bumper, is placed between the third comparative antenna 300 and the object, and millimeter waves are transmitted from each of the four output units 325 toward the object, and the reflected waves from the object and the reflected waves from the obstacle OB are received by each of the four receiving units 326.

[0088] Figure 21 shows the signal strengths of four receivers 326 when millimeter waves are transmitted from each of the four output units 325 toward an object without any objects that reflect reflected waves, such as bumpers, being placed around the antenna device 1 of this embodiment, and the reflected waves from the object are received by each of the four receivers 326. Figure 22 shows the signal strengths of four receivers 326 when an obstacle OB, which is assumed to be a bumper, is placed between the antenna device 1 of this embodiment and the object, and millimeter waves are transmitted from each of the four output units 325 toward the object, and the reflected waves from the object and the reflected waves from the obstacle OB are received by each of the four receivers 326. Note that in Figures 20 and 22, the obstacle OB is shown as a transparency to make the third comparison antenna 300 and the antenna device 1 easier to understand.

[0089] As shown in Figures 19 and 21, when no obstacle OB is placed, the signal strength of the reflected waves from the object received by the third comparison antenna 300 and the antenna device 1 is almost the same. Furthermore, the reflected wave signals received by the third comparison antenna 300 and the antenna device 1 are almost free from directional disturbances in the range of -60° to +60°.

[0090] However, when an obstacle OB is placed, the reflected wave signal from the object received by the third comparison antenna 300 is significantly more distorted in the range of -60° to +60° compared to when no obstacle OB is placed, as shown in Figure 20. Therefore, it is difficult for the third comparison antenna 300 to accurately acquire the distance to the object, the object's position, and the object's shape.

[0091] In contrast, even when an obstacle OB is placed, the reflected wave signal received by the antenna device 1 from the object can suppress directivity disturbances in the range of -60° to +60° compared to the third comparison antenna 300, as shown in Figure 22. Therefore, with the antenna device 1 of this embodiment, the antenna device 1 can accurately acquire the distance to the object, the position of the object, the shape of the object, and so on.

[0092] As described above, the antenna device 1 of this embodiment comprises an MMIC 20 for transmitting and receiving radio waves, a substrate 10 on which the MMIC 20 is arranged, and an antenna device 30 provided on the substrate 10 and forming a transmitting waveguide 33 and a receiving waveguide 34 for propagating radio waves. The antenna device 30 is stacked in the stacking direction D1 and includes a feeding side forming portion 31 and an antenna side forming portion 32, each composed of resin. The feeding side forming portion 31 and the antenna side forming portion 32 are bonded adjacent to each other in the stacking direction D1. The antenna side forming portion 32 at one end in the stacking direction D1 has an antenna surface 321 for transmitting radio waves on one side of the stacking direction D1, and an antenna side waveguide forming surface 322 that is bonded to the feeding side forming portion 31 on the other side of the stacking direction D1. The power supply side forming portion 31 at the other end in the stacking direction D1 has a power supply side waveguide forming surface 311 that is bonded to the antenna side forming portion 32 on one side in the stacking direction D1, and a substrate facing surface 312 that is bonded to the substrate 10 on the other side in the stacking direction D1. The antenna surface 321 has a resin exposed portion 3211 in which at least a part of the resin is exposed. The antenna side waveguide forming surface 322 has a leakage suppression portion 40 that suppresses the leakage of radio waves from between it and the opposing power supply side waveguide forming surface 311. The leakage suppression portion 40 is made of a material with a higher dielectric constant than the resin and has a plurality of antenna side recesses 41 that are recessed in the stacking direction D1. The resin exposed portion 3211 is formed in a portion that overlaps with the leakage suppression portion 40 in the stacking direction D1.

[0093] According to this, even if reflections from the bumper propagate to the antenna surface 321, the portion of the antenna surface 321 made up of the exposed resin portion 3211 is less likely to reflect the reflected waves. Therefore, when reflected waves from the bumper propagate to the exposed resin portion 3211, most of these reflected waves propagate from the exposed resin portion 3211 into the antenna-side forming portion 32. Then, the reflected waves propagated into the antenna-side forming portion 32 lose energy through heat exchange as they pass through the antenna-side forming portion 32. Consequently, regardless of the direction in which the reflected waves are received, the antenna surface 321 becomes less likely to reflect the received reflected waves, thus suppressing the effects of multiple reflected waves caused by repeated reflections between the bumper and the antenna surface 321.

[0094] (First modification of the first embodiment) In the first embodiment described above, an example was described in which the leakage suppression portion 40 is formed on the antenna-side forming portion 32, which is one of the power supply-side forming portion 31 and antenna-side forming portion 32 that constitute the antenna device 30, but the invention is not limited to this. For example, the leakage suppression portion 40 may be formed on the power supply-side forming portion 31.

[0095] Specifically, as shown in Figure 23, the leakage suppression portion 40 may be formed on the power supply side waveguide forming surface 311, which is one side of the power supply side forming portion 31 in the stacking direction D1. The leakage suppression portion 40 is composed of a plurality of power supply side recesses 42 in which a part of the power supply side waveguide forming surface 311 is recessed from one side to the other in the stacking direction D1. That is, the portion of the leakage suppression portion 40 in which the power supply side recesses 42 are not formed is formed in an uneven shape that protrudes to one side in the stacking direction D1 compared to the portion in which the power supply side recesses 42 are formed. The power supply side recesses 42 correspond to leakage recesses that are formed by being recessed in the stacking direction D1.

[0096] Furthermore, the leakage suppression section 40 is formed in the portion of the power supply side waveguide forming surface 311 where the first transmitting groove 315 and the first receiving groove 316 are not formed. By forming the leakage suppression section 40 on the power supply side waveguide forming surface 311, leakage of radio waves from the gap between the power supply side waveguide forming surface 311 and the antenna side waveguide forming surface 322 can be suppressed.

[0097] Furthermore, when the leakage suppression section 40 is formed on the power supply side waveguide forming surface 311, the reflected waves from the bumper need to pass through the antenna side forming section 32 to lose energy and are also reflected by the leakage suppression section 40. Therefore, the reflected waves need to pass through the antenna side forming section 32. For this reason, as shown in Figure 23, the antenna side forming section 32 is configured such that a portion of both the antenna surface 321, which is one side of the stacking direction D1, and the antenna side waveguide forming surface 322, which is the other side of the stacking direction D1, are not covered by the second conductive film 352. As a result, the resin of the portions of the antenna side forming section 321 and the antenna side waveguide forming surface 322 that are not covered by the second conductive film 352 is exposed. The portions of the antenna surface 321 and the antenna side waveguide forming surface 322 that are not covered by the second conductive film 352 are the portions that overlap with the portion of the power supply side waveguide forming surface 311 where the leakage suppression section 40 is formed, in the stacking direction D1.

[0098] According to this, when reflected waves from the bumper propagate to the antenna surface 321, they propagate into the antenna-side forming portion 32 from the portion of the antenna-side forming portion 32 that is not covered by the second conductive film 352 on one side in the lamination direction D1. Then, the reflected waves that have propagated into the antenna-side forming portion 32 lose energy through heat exchange as they pass through the antenna-side forming portion 32.

[0099] Furthermore, the reflected wave that has passed through the antenna-side forming section 32 propagates between the feed-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 from the portion of the antenna-side forming section 32 that is not covered by the second conductive film 352 on the other side in the stacking direction D1. This reflected wave is reflected by the surface of the first conductive film 351 that forms the leakage suppression section 40 of the feed-side waveguide forming surface 311 on one side in the stacking direction D1. The reflected wave reflected at the portion of the first conductive film 351 that forms the feed-side recess 42 and the reflected wave reflected at the portion that does not form the feed-side recess 42 have opposite phases to each other, causing them to cancel each other out and be attenuated. Therefore, the leakage suppression section 40, which suppresses radio wave leakage when a gap occurs between the feed-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322, can also suppress the generation of multiple reflected waves.

[0100] Furthermore, since the substrate 10 and the antenna device 30 are bonded to the substrate 10 by adhesive, there is a risk that a gap may occur between the substrate 10 and the power supply side forming portion 31. For this reason, as shown in Figure 24, the leakage suppression portion 40 may be formed on the substrate-facing surface 312, which is the other side of the power supply side forming portion 31 in the stacking direction D1. The leakage suppression portion 40 is composed of a plurality of substrate-side recesses 43 in which a part of the substrate-facing surface 312 is recessed from the other side in the stacking direction D1 toward the one side.

[0101] In other words, the leakage suppression portion 40 is formed in an uneven shape in which the portion where the substrate-side recess 43 is not formed protrudes to the other side in the stacking direction D1 compared to the portion where the substrate-side recess 43 is formed. The substrate-side recess 43 corresponds to the leakage recess formed by recessing in the stacking direction D1. By forming the leakage suppression portion 40 on the substrate-facing surface 312, leakage of radio waves from the gap between the substrate-facing surface 312 and one side of the substrate 10 in the stacking direction D1 can be suppressed.

[0102] Furthermore, when the leakage suppression section 40 is formed on the substrate-facing surface 312, the reflected waves from the bumper need to pass through the antenna-side forming section 32 to lose energy and are also reflected by the leakage suppression section 40. Therefore, the reflected waves need to pass through both the antenna-side forming section 32 and the power supply-side forming section 31. For this reason, as shown in Figure 24, the antenna-side forming section 32 is configured such that a portion of both the antenna surface 321, which is one side of the stacking direction D1, and the antenna-side waveguide forming surface 322, which is the other side of the stacking direction D1, are not covered by the second conductive film 352. As a result, the resin of the portions of the antenna-side forming section 321 and the antenna-side waveguide forming surface 322 that are not covered by the second conductive film 352 is exposed. The portions of the antenna surface 321 and the antenna-side waveguide forming surface 322 that are not covered by the second conductive film 352 are the portions that overlap with the portion of the substrate-facing surface 312 where the leakage suppression section 40 is formed, in the stacking direction D1.

[0103] Furthermore, the power supply side forming portion 31 is configured such that a portion of the power supply side waveguide forming surface 311, which is one side of the lamination direction D1, is not covered by the first conductive film 351. In this configuration, the resin of the portion of the power supply side waveguide forming surface 311 that is not covered by the first conductive film 351 is exposed. The portion of the power supply side waveguide forming surface 311 that is not covered by the first conductive film 351 is the portion that overlaps with the portion of the substrate facing surface 312 where the leakage suppression portion 40 is formed, in the lamination direction D1.

[0104] According to this, when reflected waves from the bumper propagate to the antenna surface 321, they propagate into the antenna-side forming portion 32 from the portion of the antenna-side forming portion 32 that is not covered by the second conductive film 352 on one side in the lamination direction D1. Then, the reflected waves that have propagated into the antenna-side forming portion 32 lose energy through heat exchange as they pass through the antenna-side forming portion 32.

[0105] Furthermore, the reflected wave that has passed through the antenna-side forming section 32 propagates between the feed-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 from the portion of the antenna-side forming section 32 that is not covered by the second conductive film 352 on the other side in the stacking direction D1. The reflected wave that has propagated between the feed-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 then propagates into the feed-side forming section 31 from the portion of the feed-side forming section 31 that is not covered by the first conductive film 351 on one side in the stacking direction D1. The reflected wave that has propagated into the feed-side forming section 31 then loses further energy through heat exchange as it passes through the feed-side forming section 31.

[0106] The reflected waves that have passed through the power supply side forming section 31 are reflected by the first conductive film 351 forming the leakage suppression section 40 on the substrate-facing surface 312 on one side in the stacking direction D1. Furthermore, the reflected waves reflected at the portion of the first conductive film 351 that forms the substrate-side recess 43 and the reflected waves reflected at the portion that does not form the substrate-side recess 43 have opposite phases to each other, causing them to cancel each other out and be attenuated. Therefore, the leakage suppression section 40, which suppresses radio wave leakage when a gap occurs between the substrate-facing surface 312 and the substrate 10, can also suppress the generation of multiple reflected waves.

[0107] Furthermore, in the first embodiment described above, an example was described in which the leakage suppression portion 40 is formed over almost the entire portion of the antenna-side waveguide forming surface 322, excluding the areas where the second transmitting groove portion 323 and the second receiving groove portion 324 are formed. However, electronic components such as wiring may be placed on the antenna-side waveguide forming surface 322. In this case, the leakage suppression portion 40 cannot be formed over almost the entire portion of the antenna-side waveguide forming surface 322, excluding the areas where the second transmitting groove portion 323 and the second receiving groove portion 324 are formed.

[0108] In such cases, as shown in Figure 25, the leakage suppression portion 40 may be formed on either the power supply side forming portion 31 or the antenna side forming portion 32. Specifically, the leakage suppression portion 40 may be formed on the power supply side waveguide forming surface 311 in a portion that overlaps with the portion on the antenna side waveguide forming surface 322 where the leakage suppression portion 40 cannot be formed, in the stacking direction D1.

[0109] According to this, even if there are areas on the antenna-side waveguide forming surface 322 where a leakage suppression section 40 cannot be formed, leakage of radio waves from the gap between the power supply-side waveguide forming surface 311 and the antenna-side waveguide forming surface 322 can be suppressed. In addition, the leakage suppression sections 40 formed on the power supply-side forming section 31 and the antenna-side forming section 32 can also suppress the generation of multiple reflected waves.

[0110] (Second modification of the first embodiment) In the first embodiment described above, an example was given in which the portion of the antenna surface 321 where the output section 325 and the receiving section 326 are not formed is formed in a planar shape, but the invention is not limited to this. For example, as shown in Figure 26, the antenna device 1 may have an antenna surface reflection suppression section 327 formed in the portion of the antenna surface 321 that overlaps with the second transmitting groove section 323 and the second receiving groove section 324 in the stacking direction D1, where the output section 325 and the receiving section 326 are not formed. The portion of the antenna surface reflection suppression section 327 on the antenna surface 321 is a portion that does not overlap with the leakage suppression section 40 in the stacking direction D1. That is, the portion where the antenna surface reflection suppression section 327 is formed is a portion where, when reflected waves from the bumper propagate through the antenna side forming section 32 along the stacking direction D1, the leakage suppression section 40 is not present in the path through which the reflected waves pass, and it is a portion where it is difficult to suppress the occurrence of multiple reflections by the leakage suppression section 40.

[0111] The antenna surface reflection suppression section 327 corresponds to the reflection suppression section 120 of the first comparison antenna 100, and is composed of a plurality of antenna surface recesses 3271 in which a part of the antenna surface 321 is recessed from one side to the other in the stacking direction D1. That is, the antenna surface reflection suppression section 327 is formed in an uneven shape in which the parts where the antenna surface recesses 3271 are not formed protrude to one side in the stacking direction D1 compared to the parts where the antenna surface recesses 3271 are formed. Furthermore, the antenna surface reflection suppression section 327 is covered with a second conductive film 352.

[0112] Multiple antenna surface recesses 3271 are formed at predetermined intervals along the waveguide extension direction D2 and the waveguide alignment direction D3, respectively. The size of the antenna surface recesses 3271 in the stacking direction D1 is set based on the wavelength of the millimeter waves transmitted by the MMIC 20. For example, the depth of the antenna surface recesses 3271 is set to 0.75λ, or approximately 2.94 mm.

[0113] By providing the antenna surface reflection suppression section 327 on the antenna surface 321 in this manner, the reflected waves reflected at the area where the antenna surface recess 3271 is formed and the reflected waves reflected at the area where the antenna surface recess 3271 is not formed will have opposite phases to each other. Therefore, these two reflected waves cancel each other out and are attenuated, thus suppressing the effects of multiple reflected waves. Furthermore, reflected waves propagated to the area where the antenna surface recess 3271 is formed are scattered by the space within the antenna surface recess 3271. Therefore, even when reflected waves from the bumper are incident on an area where it is difficult to suppress multiple reflections by the leakage suppression section 40, the antenna surface recess 3271 scatters the reflected waves in a direction different from the direction of incidence, thereby suppressing the generation of multiple reflected waves.

[0114] (Second Embodiment) Next, the second embodiment will be described with reference to Figures 27 to 29. In this embodiment, a dielectric adjustment section 50 is provided in the antenna-side forming section 32, and an antenna surface reflection suppression section 327 is formed therein, which is different from the first embodiment. Other than this, it is the same as the first embodiment. For this reason, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0115] As shown in Figure 27, in this embodiment, the antenna device 1 has an antenna surface reflection suppression section 327 formed in the portion of the antenna surface 321 that overlaps with the second transmitting groove section 323 and the second receiving groove section 324 in the stacking direction D1, where the output section 325 and the receiving section 326 are not formed. The portion of the antenna surface reflection suppression section 327 formed on the antenna surface 321 is a portion that does not overlap with the leakage suppression section 40 in the stacking direction D1. In other words, the portion of the antenna surface reflection suppression section 327 formed is a portion where, when reflected waves from the bumper propagate through the antenna side forming section 32 along the stacking direction D1, the leakage suppression section 40 is not present in the path through which the reflected waves pass, and it is a portion where it is difficult to suppress the occurrence of multiple reflections by the leakage suppression section 40.

[0116] The antenna surface reflection suppression section 327 corresponds to the reflection suppression section 120 of the first comparison antenna 100, and is composed of a plurality of antenna surface recesses 3271 in which a part of the antenna surface 321 is recessed from one side to the other in the stacking direction D1. That is, the antenna surface reflection suppression section 327 is formed in an uneven shape in which the parts where the antenna surface recesses 3271 are not formed protrude to one side in the stacking direction D1 compared to the parts where the antenna surface recesses 3271 are formed. Furthermore, the antenna surface reflection suppression section 327 is not covered by the second conductive film 352, and the resin is exposed.

[0117] Multiple antenna surface recesses 3271 are formed at predetermined intervals along the waveguide extension direction D2 and the waveguide alignment direction D3, respectively. The size of the antenna surface recesses 3271 in the stacking direction D1 is set based on the wavelength of the millimeter waves transmitted by the MMIC 20. For example, the depth of the antenna surface recesses 3271 is set to 0.25λ, or approximately 0.98 mm.

[0118] By providing the antenna surface reflection suppression portion 327 formed in this manner on the antenna surface 321, even if reflected waves from the bumper are incident on the antenna surface reflection suppression portion 327, the reflected waves propagate into the antenna-side forming portion 32 because the antenna surface reflection suppression portion 327 is not covered by the second conductive film 352. As a result, the reflected waves propagated into the feed-side forming portion 31 lose energy through heat exchange as they propagate within the feed-side forming portion 31.

[0119] Furthermore, even if some of the reflected waves from the bumper are reflected by the antenna surface reflection suppression unit 327, the reflected waves reflected at the area where the antenna surface recess 3271 is formed and the reflected waves reflected at the area where the antenna surface recess 3271 is not formed will have opposite phases to each other. Therefore, these two reflected waves cancel each other out and are attenuated, thus suppressing the effects of multiple reflected waves.

[0120] Furthermore, in the antenna device 1 of this embodiment, a dielectric adjustment section 50 for adjusting the dielectric constant of the antenna-side forming section 32 is formed in the portion of the antenna surface 321 where the resin exposed portion 3211 is formed. That is, the dielectric adjustment section 50 is formed in the portion of the antenna surface 321 that overlaps in the stacking direction D1 with the portion of the antenna-side waveguide forming surface 322 where the leakage suppression section 40 is formed. In other words, the dielectric adjustment section 50 is formed in the portion of the antenna surface 321 that overlaps in the stacking direction D1 with the portion of the antenna-side waveguide forming surface 322 where the second transmitting groove 323 and the second receiving groove 324 are not formed.

[0121] As shown in Figures 27 and 28, the dielectric adjustment section 50 is composed of a plurality of resin recesses 51 in which a part of the antenna surface 321 is recessed from one side to the other in the stacking direction D1. In other words, the dielectric adjustment section 50 is formed in an uneven shape in which the parts where the resin recesses 51 are not formed protrude to one side in the stacking direction D1 compared to the parts where the resin recesses 51 are formed.

[0122] The resin recesses 51 are formed in a tapered shape, with the inner diameter decreasing as you move from one side to the other in the lamination direction D1. Furthermore, the resin recesses 51 are approximately square in shape when viewed along the lamination direction D1. The spaces formed by the resin recesses 51 are approximately square pyramidal in shape, extending toward the other side of the lamination direction D1. Multiple resin recesses 51 are formed at predetermined intervals along the waveguide extension direction D2 and the waveguide alignment direction D3. In Figures 27 and 28, for convenience, representative reference numerals are assigned to each of the multiple resin recesses 51, while the numerals for others are omitted.

[0123] The spacing between the resin recesses 51 in the waveguide extension direction D2 and the waveguide alignment direction D3 is equal to each other. Furthermore, the resin recesses 51 are formed in a position that overlaps with the antenna-side recesses 41 in the stacking direction D1. Specifically, the spacing between the resin recesses 51 in the waveguide extension direction D2 and the waveguide alignment direction D3 is 0.5λ, or half the wavelength of a millimeter wave, similar to the spacing between the multiple antenna-side recesses 41. Also, the size of the resin recesses 51 in the waveguide extension direction D2 and the waveguide alignment direction D3 is set to 0.65λ, or approximately 2.54 mm, similar to the antenna-side recesses 41.

[0124] As multiple resin recesses 51 of this shape are formed on the antenna surface 321, the cross-sectional area of ​​the antenna-side forming portion 32 increases perpendicular to the stacking direction D1 as you move from one side to the other in the stacking direction D1. In other words, in the area where the dielectric adjustment portion 50 is formed, the unit volume of the antenna-side forming portion 32 increases as you move from one side to the other in the stacking direction D1. In this embodiment, where the resin recesses 51 are formed in a tapered shape, the unit volume of the antenna-side forming portion 32 increases continuously and gradually as you move from one side to the other in the stacking direction D1.

[0125] Next, the reason why the dielectric adjustment section 50 is provided in the area where the resin exposed section 3211 is formed will be explained with reference to Figure 29. The dashed line in Figure 29 shows the reflection suppression effect of the leakage suppression section 40 when the dielectric adjustment section 50 is not provided in the resin exposed section 3211, and the solid line in Figure 29 shows the reflection suppression effect of the leakage suppression section 40 when the dielectric adjustment section 50 is provided in the resin exposed section 3211. In other words, the dashed line in Figure 29 shows the reflection suppression effect of the leakage suppression section 40 in the configuration of the antenna device 1 of the first embodiment, and the solid line in Figure 29 shows the reflection suppression effect of the leakage suppression section 40 in the configuration of the antenna device 1 of the second embodiment.

[0126] As described in the first embodiment, by providing a resin exposed portion 3211 on the antenna surface 321 and a leakage suppression portion 40 on the antenna-side waveguide forming surface 322, reflected waves from the bumper are less likely to be reflected by the antenna surface 321. Here, the recess depth H of the leakage suppression portion 40 is set to 0.25λ. As shown in Figure 12, the reflection suppression effect by the leakage suppression portion 40 can achieve a greater attenuation when the recess depth H is slightly greater than 0.25λ than when the recess depth H is set to 0.25λ. In other words, the recess depth H set to 0.25λ is offset from the recess depth H that results in the minimum value in the reflection suppression effect, which periodically changes so that the maximum and minimum values ​​alternate at intervals of approximately 1 / 4λ.

[0127] Therefore, if the recess depth H is made slightly larger than 0.25λ compared to the configuration of the antenna device 1 described in the first embodiment, the leakage suppression unit 40 can further attenuate the signal strength of the reflected wave from the bumper. However, as explained in Figure 5, the effect of suppressing radio wave leakage is more easily increased when the recess depth H is set to a size that is an odd number multiplied by 1 / 4λ, such as 0.25λ or 0.75λ. For this reason, from the viewpoint of suppressing radio wave leakage from the gap between the feed side waveguide forming surface 311 and the antenna side waveguide forming surface 322, it is desirable that the recess depth H be 0.25λ.

[0128] As described above, when the reflected wave from the bumper propagates into the antenna-side forming section 32, its wavelength is shortened as it passes through the resin-based antenna-side forming section 32 compared to before it propagated into the antenna-side forming section 32. This is because the dielectric constant of the resin is significantly larger than that of air.

[0129] The amount by which the wavelength of the reflected wave is shortened by passing through the antenna-side forming section 32 is determined by the dielectric constant of the antenna-side forming section 32. Specifically, the amount of shortening of the wavelength of the reflected wave increases as the dielectric constant of the antenna-side forming section 32 increases, and decreases as the dielectric constant decreases. The dielectric constant of the antenna-side forming section 32 changes according to the unit volume of the antenna-side forming section 32.

[0130] In this embodiment, the antenna-side forming portion 32 is provided with a dielectric adjustment portion 50, which is composed of a plurality of resin recesses 51 that are recessed from one side to the other in the lamination direction D1, in the area where the resin exposed portion 3211 is formed. As a result, in this embodiment, the unit volume of the portion of the antenna-side forming portion 32 where the dielectric adjustment portion 50 is provided is smaller compared to the case where the dielectric adjustment portion 50 is not provided.

[0131] Therefore, the dielectric constant of the antenna-side forming portion 32 is smaller compared to the case where the dielectric adjustment portion 50 is not provided. Consequently, the amount of shortening of the wavelength of the reflected wave that is shortened by passing through the antenna-side forming portion 32 is smaller compared to the case where the dielectric adjustment portion 50 is not provided. In other words, the wavelength of the reflected wave that passes through the antenna-side forming portion 32 is larger compared to the case where the dielectric adjustment portion 50 is not provided.

[0132] Therefore, as shown in Figure 29, when the leakage suppression unit 40 attenuates the signal intensity of the reflected wave, the period during which the attenuation amount changes periodically according to the depression depth H is larger compared to the case where the dielectric adjustment unit 50 is not provided. Consequently, as shown in Figure 29, in the reflection suppression effect which periodically changes so that the maximum value and minimum value alternate at intervals of approximately 1 / 4λ, the depression depth H at which the minimum value occurs can be made larger compared to the case where the dielectric adjustment unit 50 is not provided.

[0133] Furthermore, when adjusting the dielectric constant of the antenna-side forming portion 32 by the exposed resin portion 3211, the amount of adjustment can be changed by the size of the stacking direction D1 of the resin recess portion 51. For this reason, in this embodiment, the size of the stacking direction D1 of the resin recess portion 51 is set such that when the recess depth H is 0.25λ, the signal intensity of the reflected wave from the bumper can be minimized by the leakage suppression portion 40. This makes it possible to set the recess depth H to a size that allows for a large reflection suppression effect by the leakage suppression portion 40 while ensuring the effect of suppressing radio wave leakage from the gap between the power supply side waveguide forming surface 311 and the antenna side waveguide forming surface 322.

[0134] Incidentally, even when a resin exposed portion 3211 is formed on the antenna surface 321, there is a risk that some of the reflected waves from the bumper may be reflected by the antenna surface 321 when they are incident on the antenna surface 321. For this reason, it is desirable that the antenna surface 321 be configured to be less likely to reflect reflected waves from the bumper.

[0135] Here, when reflected waves from the bumper are incident on the resin exposed portion 3211, the greater the difference in dielectric constant between the air and the antenna-side forming portion 32, the more likely reflection will occur at the resin exposed portion 3211. In contrast, the dielectric adjustment portion 50 of this embodiment is formed in a tapered shape where the resin recess portion 51 becomes smaller as it moves from one side to the other in the stacking direction D1. Furthermore, the unit volume of the antenna-side forming portion 32 increases as it moves from one side to the other in the stacking direction D1.

[0136] Therefore, when reflected waves from the bumper pass through the antenna-side forming portion 32, the dielectric constant of the antenna-side forming portion 32 gradually increases from one side to the other in the stacking direction D1. As a result, the difference in dielectric constant between the air and the antenna-side forming portion 32 gradually increases. Consequently, when forming the resin exposed portion 3211 on the antenna surface 321, the occurrence of reflection in the resin exposed portion 3211 when reflected waves from the bumper are incident on the resin exposed portion 3211 can be suppressed. Furthermore, since the resin recessed portion 51 is formed in a tapered shape, if the resin recessed portion 51 is formed using a mold, it becomes easier to remove the mold from one side in the stacking direction D1.

[0137] As described above, the resin exposed portion 3211 of the antenna device 1 of this embodiment has a dielectric adjustment portion 50 having a plurality of resin recesses 51 that are recessed on the other side in the stacking direction D1.

[0138] According to this, the dielectric adjustment unit 50 can adjust the amount of shortening of the wavelength of the reflected wave that is shortened by passing through the antenna-side forming unit 32. Therefore, even if there is a discrepancy between the size of the recess H that allows the leakage suppression unit 40 to greatly increase the suppression effect of radio wave leakage and the size of the recess H that allows the reflection suppression effect to greatly increase, the dielectric adjustment unit 50 can bring the recess H that allows the reflection suppression effect to greatly increase closer to the recess H that allows the radio wave leakage suppression effect to greatly increase. Thus, the reflection suppression effect of the leakage suppression unit 40 can be greatly increased while ensuring the suppression effect of radio wave leakage from the gap between the power supply side waveguide forming surface 311 and the antenna side waveguide forming surface 322.

[0139] The other configurations are the same as in the first embodiment. The antenna device 1 of this embodiment can obtain the same effects and advantages as in the first embodiment, which are achieved from a configuration that is the same as or equivalent to that of the first embodiment.

[0140] (First modified example of the second embodiment) In the second embodiment described above, an example was described in which the resin recess 51 is formed in a tapered shape, with the inner diameter decreasing as it moves from one side to the other in the stacking direction D1. However, the invention is not limited to this. For example, as shown in Figure 30, the resin recess 51 may not be tapered, and the space formed by the resin recess 51 may be in the shape of a rectangular parallelepiped.

[0141] (Second modified example of the second embodiment) In the second embodiment described above, an example was given in which the size of the resin recess 51 in the waveguide extension direction D2 and the waveguide alignment direction D3 were set to 0.65λ, similar to the antenna-side recess 41, but the invention is not limited to this. For example, as shown in Figure 31, the resin recess 51 may be formed with a size larger than that of the antenna-side recess 41 in the waveguide extension direction D2 and the waveguide alignment direction D3. Alternatively, although not shown, the resin recess 51 may be formed with a size smaller than that of the antenna-side recess 41 in the waveguide extension direction D2 and the waveguide alignment direction D3.

[0142] (Third modified example of the second embodiment) In the second embodiment described above, the resin recess 51 is formed at a position overlapping with the antenna-side recess 41 in the stacking direction D1, and an example was described in which multiple resin recesses are formed at 0.5λ intervals in both the waveguide extension direction D2 and the waveguide alignment direction D3, but the invention is not limited to this. The resin recess 51 may be formed at a position that does not overlap with the antenna-side recess 41 in the stacking direction D1. In this case, the spacing between the resin recesses 51 in both the waveguide extension direction D2 and the waveguide alignment direction D3 may be smaller or larger than 0.5λ.

[0143] (Fourth modified example of the second embodiment) In the second embodiment described above, an example was described in which the resin recess 51 is formed in a tapered shape, with the inner diameter decreasing as it moves from one side to the other in the stacking direction D1. However, the invention is not limited to this. For example, the resin recess 51 may be formed such that the wall surface surrounding the resin recess 51 is formed in a stepped shape, with the inner diameter decreasing in stages as it moves from one side to the other in the stacking direction D1. (Fifth variation of the second embodiment) In the second embodiment described above, an example was described in which the dielectric adjustment portion 50 is composed of a plurality of resin recesses 51 that are recessed from one side to the other in the lamination direction D1, but the invention is not limited to this. For example, the dielectric adjustment portion 50 may be composed of a plurality of protrusions that project from the other side to the one side in the lamination direction D1. Alternatively, the dielectric adjustment portion 50 may be composed of a plurality of resin recesses 51 that are recessed from one side to the other in the lamination direction D1, and a plurality of protrusions that project from the other side to the one side in the lamination direction D1.

[0144] (Third embodiment) Next, the third embodiment will be described with reference to Figures 32 to 35. This embodiment differs from the first embodiment in that a resonant portion 60 is provided in the antenna-side forming portion 32. Other than this, it is the same as the first embodiment. Therefore, in this embodiment, the parts that differ from the first embodiment will be mainly described, and the parts that are the same as the first embodiment may be omitted from the description.

[0145] As shown in Figure 32, the antenna device 1 of this embodiment has a resonant portion 60 formed on the antenna surface 321 in the area where the resin exposed portion 3211 is formed, which resonates the reflected waves from the bumper. The resonant portion 60 is formed on the antenna surface 321 in the area that overlaps with the area where the leakage suppression portion 40 is formed on the antenna-side waveguide forming surface 322 in the stacking direction D1. In other words, the resonant portion 60 is formed on the antenna-side waveguide forming surface 322 in the area that overlaps with the area where the second transmitting groove portion 323 and the second receiving groove portion 324 are not formed in the stacking direction D1.

[0146] As shown in Figures 33 and 34, the resonant portion 60 is composed of multiple thin-film resonant patterns 61 formed of metal on the resin exposed portion 3211. Therefore, compared to the resin exposed portion 3211 of the first embodiment, the antenna surface 321 of this embodiment is covered with metal in the area where the multiple resonant patterns 61 are formed.

[0147] The resonance pattern 61 is formed by repeatedly folding back along the waveguide extension direction D2 and on both sides of the waveguide alignment direction D3. Furthermore, the dimension of the resonance pattern 61 in the waveguide extension direction D2 is larger than the dimension in the waveguide alignment direction D3. As shown in Figure 34, the resonance pattern 61 has a plurality of first pattern portions 611 extending along the waveguide extension direction D2 on one side of the waveguide alignment direction D3, a plurality of second pattern portions 612 extending along the waveguide extension direction D2 on the other side of the waveguide alignment direction D3, and a plurality of third pattern portions 613 extending along the waveguide alignment direction D3 and connecting the first pattern portions 611 and the second pattern portions 612.

[0148] The amplitude D2 of each of the multiple first pattern sections 611 and multiple second pattern sections 612 corresponds to the millimeter wave frequency band transmitted by the MMIC 20. Similarly, the amplitude D3 of each of the multiple third pattern sections 613 corresponds to the millimeter wave frequency band transmitted by the MMIC 20. The resonant pattern 61, which is formed by connecting the multiple first pattern sections 611, multiple second pattern sections 612, and multiple third pattern sections 613, is formed to resonate with the received reflected wave when it receives a reflected wave from the bumper.

[0149] Furthermore, multiple resonance patterns 61 are arranged at predetermined intervals in both the waveguide extension direction D2 and the waveguide alignment direction D3. Multiple resonance patterns 61 are positioned within the area of ​​the antenna surface 321 where the resin exposed portion 3211 is formed. In Figure 34, for convenience, representative symbols are assigned to each of the multiple resonance patterns 61, while symbols are omitted for others.

[0150] The resonance pattern 61 can be formed, for example, by applying a masking treatment to the areas excluding the area where the resonance pattern 61 is to be formed when forming the resin exposed area 3211 on the antenna surface 321, thereby preventing the formation of the second conductive film 352 in the areas excluding the masked area. Alternatively, the resonance pattern 61 can be formed by the second conductive film 352 by forming the second conductive film 352 over the entire antenna surface 321, and then removing the second conductive film 352 from the areas excluding the area where the resonance pattern 61 is to be formed by laser processing or the like.

[0151] By providing a resonant section 60 on the antenna surface 321 in this way, as shown in Figure 35, the reflected wave from the bumper can be resonated by multiple resonant patterns 61, and the energy of the received reflected wave can be attenuated by heat exchange. Figure 35 shows the electric field distribution when the antenna surface 321 receives the reflected wave from the bumper. By resonating the reflected wave from the bumper with the resonant patterns 61, as shown in Figure 35, the energy of the electric field caused by the reflected wave can be attenuated as you move from one side to the other in the stacking direction D1.

[0152] As described above, the resin exposed portion 3211 of the antenna device 1 in this embodiment is provided with a resonant portion 60 that resonates the radio waves received by the antenna surface 321. This allows the reflected waves from the bumper to resonate with the resonant portion 60, and the energy of the received reflected waves to be attenuated by heat exchange. Therefore, because the reflected waves from the bumper are less likely to be reflected by the antenna surface 321 due to the resonant portion 60, the effects of multiple reflected waves, which are radio waves repeatedly reflected between the bumper and the antenna surface 321, can be suppressed.

[0153] The other configurations are the same as in the first embodiment. The antenna device 1 of this embodiment can obtain the same effects and advantages as in the first embodiment, which are achieved from a configuration that is the same as or equivalent to that of the first embodiment.

[0154] (First modified example of the third embodiment) In the third embodiment described above, an example was described in which the resonant portion 60 is composed of a plurality of resonant patterns 61 that extend along the waveguide extension direction D2 and are repeatedly folded back on one side and the other side of the waveguide alignment direction D3, respectively. However, the embodiment is not limited to this. For example, as shown in Figure 36, the resonant portion 60 may be composed of a plurality of resonant patterns 61 that are formed in a rectangular shape when viewed along the stacking direction D1. Alternatively, as shown in Figure 37, the resonant portion 60 may be configured in which a plurality of resonant patterns 61 composed of two rectangular annular portions of different sizes are arranged when viewed along the stacking direction D1. In this case, as shown in Figure 37, each of the two rectangular annular portions of different sizes has a portion missing, and the direction of the missing portion when viewed from the center of the resonant pattern 61 is different from that of the others. Alternatively, as shown in Figure 38, the resonant portion 60 may be composed of a plurality of resonant patterns 61 that are formed in an oval shape when viewed along the stacking direction D1.

[0155] (Second modified example of the third embodiment) In the third embodiment described above, an example was given in which the resonant portion 60 is composed of a thin film-like resonant pattern 61 made of metal, but the invention is not limited to this. For example, the resonant portion 60 may be composed of a resin exposed portion 3211 on the antenna surface 321 in which the resin is exposed, causing the reflected waves from the bumper to resonate. In this case, for example, as shown in Figure 39, the resin exposed portion 3211 may have multiple portions that extend along the waveguide extension direction D2 and are repeatedly folded back and exposed on one side and the other side of the waveguide alignment direction D3, and the resonant pattern 61 may be composed of these exposed portions. Alternatively, as shown in Figure 40, the resin exposed portion 3211 may have multiple portions that are exposed in an oval shape when viewed in the direction along the lamination direction D1, and the resonant pattern 61 may be composed of these exposed portions. Note that in Figures 39 and 40, portions on the antenna surface 321 covered by the second conductive film 352 are shown with hatching.

[0156] (Other embodiments) While typical embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0157] In the embodiments described above, an example was described in which the antenna device 30 is composed of two waveguides, a feeding-side forming section 31 and an antenna-side forming section 32, but the invention is not limited to this. For example, the antenna device 30 may be configured to include one or more waveguides between the feeding-side forming section 31 and the antenna-side forming section 32. In this case, the leakage suppression section 40 may be formed on one side and the other side of the waveguide in the stacking direction D1 in the waveguide provided between the feeding-side forming section 31 and the antenna-side forming section 32.

[0158] In the embodiments described above, an example was given in which the antenna device 1 of the present disclosure is applied to a vehicle and mounted inside a bumper (not shown) of the vehicle, but it is not limited thereto. The antenna device 1 can be applied to a variety of things other than vehicles.

[0159] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0160] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0161] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc. [Explanation of Symbols]

[0162] 10 circuit boards 30 Antenna section 31 Waveguide No. 2 32 Waveguide 1 40 Leakage suppression section 311 Second waveguide surface 312 Substrate opposing surface 321 Antenna surface 322 First waveguide surface 3211 Exposed resin part

Claims

1. An antenna device, A transmitting and receiving unit (20) that transmits and receives radio waves, A circuit board (10) on which the transmitting and receiving unit is located, The antenna section (30) is provided on the substrate and forms waveguides (33, 34) for propagating the radio waves, The antenna portion includes a plurality of waveguide forming portions (31, 32) which are stacked in the stacking direction when the alignment direction of the substrate and the antenna portion is defined as the stacking direction, and each of them is made up of resin. The plurality of waveguide forming portions are bonded together when adjacent waveguide forming portions are in the stacking direction. Of the plurality of waveguide forming portions, the waveguide forming portion at one end in the stacking direction has an antenna surface (321) for transmitting radio waves on one side in the stacking direction. Of the plurality of waveguide forming portions, the waveguide forming portion at the end on the other side in the stacking direction has a substrate-facing surface (312) that is bonded to the substrate on the other side in the stacking direction. When one of the adjacent waveguide forming sections in the stacking direction is designated as the first waveguide forming section (32), and the other of the adjacent waveguide forming sections in the stacking direction is designated as the second waveguide forming section (31), The first waveguide forming portion has a first waveguide surface (322) that is bonded to the second waveguide forming portion on the other side in the stacking direction, The second waveguide forming portion has a second waveguide surface (311) that is bonded to the first waveguide forming portion on one side in the stacking direction, The antenna surface has a resin exposed portion (3211) in which the resin is exposed in at least a part of it. At least one of the substrate-facing surface, the first waveguide surface, and the second waveguide surface has a leakage suppression portion (40) that suppresses the leakage of radio waves from between it and the opposing surface. The leakage suppression portion has a higher electrical conductivity than the resin and has a plurality of leakage recesses (41, 42, 43) that are recessed in the lamination direction. The aforementioned resin exposed portion is formed to include a portion that overlaps with the leakage suppression portion in the lamination direction, in an antenna device.

2. The antenna device according to claim 1, wherein a dielectric adjustment portion (50) with an uneven shape is formed on the resin exposed portion.

3. The antenna device according to claim 1, wherein the resin exposed portion is provided with a resonant portion (60) that causes the radio waves received by the antenna surface to resonate.

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