Antenna device

Abstract

The antenna device (1) comprises: a dielectric substrate (2), a bottom plate (3) arranged on a first surface of the dielectric substrate, an antenna unit (4) arranged on a second surface of the dielectric substrate, and a reflecting unit (5). The reflecting unit is arranged around the antenna unit and has a plurality of conductor patches that function as reflecting plates. The plurality of conductor patches form a plurality of blocks arranged along a predetermined block arrangement direction. The plurality of blocks are configured so that the phase of the reflected wave at the operating frequency is different for each of the blocks, and the phase difference of the reflected wave between the adjacent blocks is unevenly different for each adjacent block.

Description

[0001] This application is a divisional application of the invention patent application with application number 201680073428.6, the date of entering the Chinese national phase on June 14, 2018, and the invention name being “Antenna Device”. Technical Field

[0002] The present disclosure relates to an antenna device using a dielectric substrate. Background Art

[0003] Antennas formed on dielectric substrates are used in radars or the like for monitoring the surroundings of mobile objects such as vehicles and airplanes.

[0004] When such an antenna is used as an antenna for a vehicle-mounted radar device, it can be installed in the bumper of the vehicle, for example. In this case, it is known that part of the radio wave radiated from the antenna is reflected by the inner wall of the bumper and further reflected by the radiation surface of the antenna, and the re-reflected wave interferes with the radiation wave, thus adversely affecting the radiation characteristics of the antenna.

[0005] In this regard, the following reference 1 discloses a technology for making the reflection direction of electromagnetic waves face a desired direction using an electromagnetic wave reflection surface of a planar substrate structure. The electromagnetic wave reflection surface of the planar substrate structure has a plurality of conductor patches arranged at predetermined intervals and a connection element that electrically connects the conductor patches to each other on the other side of a substrate having a bottom plate formed on one side. The connection element is formed by increasing or decreasing the capacitance or inductance according to the configuration position along a desired direction, so that the wavefront of the reflected wave reflected on the electromagnetic reflection surface can be tilted.

[0006] In addition, it is also known that in this type of antenna, due to surface waves propagating on the substrate surface, radiation different from the main antenna radiation is generated at the substrate end or the like, causing disturbance in directivity.

[0007] In this regard, for example, the following patent document 2 discloses a technique for suppressing directivity disturbance by forming a structure having a band gap (hereinafter referred to as EBG) on a substrate that prevents surface waves from propagating at a specific frequency used by an antenna. The EBG has a structure in which small hexagonal metal plates are periodically arranged two-dimensionally on the surface of a substrate and connected to a metal plate formed on the back side of the substrate using through holes formed of metal.

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-193345

[0009] Patent Document 2: Japanese Patent Application Publication No. 2003-304113

[0010] After detailed research, the inventors found that Patent Document 1 has the following problem: due to the use of an electromagnetic reflection surface, a strong beam different from the main beam is formed in the reflection direction of the re-reflected wave from the antenna radiation surface, which may cause erroneous detection of the target.

[0011] In addition, after detailed research, the inventor found that Patent Document 2 has the following problem: since the EBG that requires a through hole to be formed in the substrate is used, the structure of the substrate becomes complicated. In addition, the EBG uses LC resonance in principle to prevent the propagation of surface waves that cause disturbance of directivity. Therefore, after detailed research, the inventor found that the EBG has the following problem: the frequency band that can be prevented is narrow, and it is difficult to apply to broadband antennas. Summary of the invention

[0012] In one embodiment of the present disclosure, it is desirable to provide a technology that can sufficiently suppress the influence of reflected waves even when the device is installed in an environment where radio waves are reflected.

[0013] In another aspect of the present disclosure, it is desirable to provide a technology for suppressing the influence of surface waves with a simple structure.

[0014] An antenna device according to one embodiment of the present disclosure comprises a dielectric substrate having a first surface and a second surface, a bottom plate, an antenna unit, and a reflector. The bottom plate is arranged on the first surface of the dielectric substrate and functions as an antenna ground plane. The antenna unit is arranged on the second surface of the dielectric substrate and has an antenna pattern that functions as an array antenna. The reflector is arranged around the antenna unit and has a plurality of conductor patches, each of which has a size smaller than a wavelength at a preset operating frequency and functions as a reflector. In addition, the plurality of conductor patches form a plurality of blocks arranged along a preset block arrangement direction. In addition, the plurality of blocks are configured so that the phase of the reflected wave at the operating frequency of each block is unevenly different.

[0015] According to such a structure, by using the second surface of the dielectric substrate as the radiation surface, the reflected wave incident on the radiation surface can be reflected in various directions instead of being reflected in a fixed direction, that is, the reflection can be scattered. As a result, when the reflected wave coming from the radiation direction of the radiation wave is re-reflected on the radiation surface, the reflection intensity of the re-reflected wave in the same direction as the radiation wave can be reduced. Therefore, it is possible to suppress the interference caused by the re-reflected wave without forming a strong beam based on the re-reflected wave in a specific direction.

[0016] The antenna device involved in another embodiment of the present disclosure includes a dielectric substrate having a first surface and a second surface, a bottom plate, an antenna unit, and an additional functional unit. The bottom plate is arranged on the first surface of the dielectric substrate and functions as an antenna ground plane. The antenna unit is arranged on the second surface of the dielectric substrate and has an antenna pattern that functions as a radiating element. The additional functional unit is arranged around the antenna unit and has a plurality of conductor patches each having a size smaller than a wavelength at a preset operating frequency. In addition, the plurality of conductor patches form a plurality of blocks arranged along a preset block arrangement direction. The phase difference between the plurality of blocks of the radiated waves from the plurality of conductor patches caused by the surface waves propagating on the surface of the dielectric substrate is set so that the radiated waves are radiated toward a compensation azimuth, which is an azimuth with the smallest gain in the antenna characteristics when the additional functional unit is removed.

[0017] According to such a configuration, the gain in the compensation direction can be improved and the bandwidth can be expanded with a simple configuration compared to EBG. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is an xy plane view which is a front view of the antenna device.

[0019] Figure 2 This is an xz plane view which is a side view of the antenna device.

[0020] Figure 3 This is a graph showing frequency characteristics of the phase of a reflected wave at a conductor patch obtained with the phase of a reflected wave at a conventional substrate as a reference when the size of the conductor patch is variously changed.

[0021] Figure 4 This is an explanatory diagram schematically showing the reflection direction at the radiation surface of a conventional substrate without a conductor patch.

[0022] Figure 5 This is an explanatory diagram schematically showing the reflection direction on the radiation surface of the substrate in which the phase difference of the reflected waves generated between the conductor patches extending across the adjacent blocks is constant.

[0023] Figure 6 This is an explanatory diagram schematically showing the reflection direction on the radiation surface of the substrate in which the phase difference of the reflected waves generated between the conductor patches across the adjacent blocks is gradually increased.

[0024] Figure 7 This is a table showing the phase differences of reflected waves generated between blocks in Examples 1 and 2 and Comparative Examples 1 and 2.

[0025] Figure 8 This is a graph showing simulation results of obtaining the reflection intensity when light enters from the front side of the antenna device, that is, from a direction with a reflection direction of 0 degrees, based on the reflection intensity on a normal substrate.

[0026] Fig. 9 This is a graph showing simulation results for obtaining the gain variation of the antenna gain after being affected by interference due to the presence of the bumper, using the antenna gain in the absence of the bumper as a reference.

[0027] Fig.10 It is an explanatory diagram schematically showing reflected waves generated by a bumper.

[0028] Fig.11 This is a graph showing simulation results of obtaining reflection intensity when the phase delay is set to increase monotonically from one end toward the other end in the block arrangement direction of the dielectric substrate.

[0029] Fig.12 The graph shows the frequency characteristics of the phase of the reflected wave at the conductor patch with the phase of the reflected wave at the normal substrate as a reference, when the size of the gap between the patches is variously changed.

[0030] Fig.13 This is an xy plane view which is a front view of the antenna device according to the second embodiment.

[0031] Fig.14 It is an xz plane view which is a side view of the antenna device according to the second embodiment.

[0032] Fig.15 This is a graph showing frequency characteristics of the phase of the reflected wave obtained at the conductor patch by variously changing the size of the conductor patch.

[0033] Fig.16 This is a table showing the phase differences of surface radiation waves generated between blocks in Example 3 and Comparative Examples 3 and 4.

[0034] Fig.17 The graphs show simulation results of obtaining the radiation characteristics of the entire antenna device when there is an additional functional portion and when the radiation phase difference of the surface current between the antenna elements constituting the additional functional portion is changed.

[0035] Fig.18 This is a graph showing simulation results for obtaining the radiation characteristics of an additional function portion formed on one side of an antenna.

[0036] Fig.19 The graphs show simulation results of obtaining the radiation characteristics of the entire antenna device in the case where the additional functional portion is present and the case where an EBG is provided instead of the additional functional portion.

[0037] Fig. 20 It is an explanatory diagram showing a modified example of the shape of a conductor patch included in the additional function portion.

[0038] Fig.21 It is an explanatory diagram showing a modified example of the shape of a conductor patch included in the additional function portion.

[0039] Fig. 22 This is a graph showing frequency characteristics of the phase of the reflected wave at the conductor patch obtained by variously changing the size of the gap between the patches. DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0041] [1. First embodiment]

[0042] [1-1. Structure]

[0043] The antenna device 1 constitutes a millimeter wave radar that is installed in a bumper of a vehicle and detects various targets existing around the vehicle.

[0044] like Figure 1 as well as Figure 2 As shown, the antenna device 1 is formed of a copper pattern formed on a rectangular dielectric substrate 2. Hereinafter, one side of the dielectric substrate 2 is referred to as a substrate surface 2a, and the other side is referred to as a substrate back side 2b. In addition, the direction along one side of the dielectric substrate 2 is referred to as an x-axis direction, the direction along the other side orthogonal to the x-axis direction is referred to as a y-axis direction, and the normal direction of the substrate surface 2a is referred to as a z-axis direction.

[0045] A base plate 3 including a copper pattern covering the entire surface of the substrate back surface 2b is formed on the substrate back surface 2b. An antenna portion 4 is formed near the center of the substrate front surface 2a, and a reflector 5 is formed around the antenna portion 4. Hereinafter, the substrate front surface 2a is also referred to as a radiation surface.

[0046] The antenna unit 4 includes a plurality of array antennas arranged along the x-axis direction. Each array antenna includes a plurality of rectangular patch antennas 41 arranged along the y-axis direction and a power supply line 42 for supplying power to each patch antenna 41. The antenna unit 4 is configured so that the polarization direction of the radio wave radiated from the antenna unit 4 coincides with the x-axis direction.

[0047] The reflector 5 includes a plurality of conductor patches P including rectangular copper patterns arranged two-dimensionally. Each conductor patch P is formed in a square shape, and the size of one side thereof is set to be smaller than the wavelength λ at the operating frequency of the antenna device 1. More specifically, it is desirable that the size of one side of each conductor patch P is less than 3 / 4 wavelength, and a size of about 1 / 5 to 1 / 3 wavelength is used here.

[0048] In the reflector 5, a plurality of rows of conductive patches P are arranged along the y-axis direction. In each row, conductive patches P of the same size are arranged in a row. The conductive patches P of each row form a block B. In addition, a plurality of blocks B are arranged along the x-axis direction. In other words, the arrangement direction of the block B is consistent with the x-axis direction. The size of the conductive patches P is different in each block B. Among them, the gaps between the conductive patches P in the block B and the gaps between the conductive patches P across the adjacent blocks B are set to a constant size.

[0049] The reflector 5 has two parts 51 and 52 with the block center as the boundary. The block center refers to a line along the y-axis direction passing through the center position of the reflector 5 in the x-axis direction. The multiple blocks B included in these two parts 51 and 52, and the multiple conductor patches P included in each block B have a structure that is line-symmetrical with respect to the block center. In the following, the block B closest to the block center in each part 51 and 52 is represented as B1, and then each block B is represented as B2, B3, ... as it moves away from the block center.

[0050] In addition, in the reflection part 5, the conductor patch P has an inductance element. In addition, the gap between the conductor patches P has a capacitance element. In other words, in the reflection part 5, if it is expressed as an equivalent circuit, it is as follows Figure 2 As shown, the number of series circuits of inductance and capacitance corresponding to the number of blocks B is connected in series with each other. Then, for the current flowing through the radiation surface 2a, the inductance element causes a phase delay, while the capacitance element causes a phase advance.

[0051] Using this property, each block Bi in the reflection unit 5 is designed to satisfy the following conditions (1) to (3). That is, (1) the phase characteristics of the reflected wave are linearly symmetric across the block center. (2) the farther from the block center, the greater the phase delay. (3) the farther from the block center, the greater the phase difference between adjacent blocks. In other words, the phase difference is tilted.

[0052] Here, the reflecting portion 5 is designed by adjusting the size of the conductor patch P included in each block Bi.

[0053] [1-2. Design]

[0054] The reflector 5 of the antenna device 1 is designed, for example, as follows.

[0055] Figure 3It is a graph showing the reflection characteristics used in the design. Specifically, it is the phase characteristic of the reflected wave reflected by the conductor patch P for the incoming wave coming from the front direction of the antenna (hereinafter referred to as the reflection characteristic). Here, the reflection characteristic is based on the phase of the reflected wave on a substrate that does not have a reflection portion 5, that is, a conventional substrate. In addition, the gap between the conductor patches P is fixed to 1 mm, and the size of one side of the conductor patch P is varied between 2.5 mm and 3.3 mm. That is, when the size of the conductor patch P is kept constant, the higher the operating frequency, the greater the phase delay. In addition, when the operating frequency is kept constant, the larger the size of the conductor patch P, the greater the phase delay. Figure 3 In FIG. 1 , the phase difference is shown in the range of −180 degrees to 180 degrees, so the phase difference of −180 degrees and 180 degrees are regarded as the same.

[0056] First, the size of the conductor patch P of the block Bi serving as the reference is arbitrarily determined. Figure 3 The size of the conductor patch P of the block Bi adjacent to the block Bi with the determined size is set so as to obtain a predetermined phase difference at a predetermined operating frequency. By repeating this process in sequence, the sizes of the conductor patches P of all the blocks Bi are designed.

[0057] [1-3. Function]

[0058] In the case of a conventional substrate without the conductor patch P or in the case where the reflection portion 5 is designed so that the phase difference of the reflected wave between the blocks B is 0 degree, as shown in FIG. Figure 4 As shown, incident light from the z-axis direction bounces back with the same phase at any part of the radiation surface 2a. As a result, the reflected light goes in the direction from which the incident light came.

[0059] When the phase difference between blocks B is constant, that is, in a configuration equivalent to the prior art that does not satisfy the above condition (3), as shown in FIG. Figure 5 As shown, the incident light from the z-axis direction is reflected on the radiation surface 2a, and the reflected light becomes a reflected light whose phase is delayed as it is farther from the block center. The phase delay is proportional to the distance from the block center. As a result, the reflected light is reflected in a constant direction having a certain angle relative to the direction of the incident light. In other words, a reflection characteristic equivalent to reflection on a flat refractive substrate bent into a mountain shape can be obtained.

[0060] In the case of the present embodiment where the phase difference between blocks B is tilted, as shown in FIG. Figure 6As shown, the incident light from the z-axis direction is reflected on the radiation surface 2a, and the farther from the block center, the more the phase of the reflected light is delayed. The farther from the block center, the faster the phase delay increases. As a result, the reflected light is reflected in a direction having a certain angle relative to the direction of the incident light, and the farther from the block center, the larger the reflection angle. In other words, a reflection characteristic equivalent to reflection on a curved substrate can be obtained, and the reflected light is scattered and directed in various directions, rather than in a constant direction.

[0061] [1-4. Effect]

[0062] According to the first embodiment described in detail above, the following effects are obtained.

[0063] (1a) Although the antenna device 1 is configured using the planar dielectric substrate 2, the reflected wave reflected on the radiation surface 2a can be scattered in various directions around it, rather than being directed in the front or in a predetermined fixed direction. As a result, even if the antenna device 1 is installed in the bumper of a vehicle, the influence of interference caused by the reflected wave from the bumper can be suppressed.

[0064] (1b) The antenna device 1 utilizes the inductance element of the conductor patch P and the capacitance element of the gap between the conductor patches P. Therefore, unlike the prior art, it is not necessary to configure a connecting element between the conductor patches P. As a result, the antenna device 1 can be applied to the millimeter wave band where the gap between the conductor patches P is extremely narrow without any problem.

[0065] [1-5. Experiment]

[0066] The results of simulations performed on Examples 1 and 2 and Comparative Examples 1 and 2 are described below. Figure 7 As shown, in Example 1, the increase in the phase difference between adjacent blocks B is set to 30 degrees. In Example 2, the increase in the phase difference is set to 50 degrees. In Comparative Example 1, a conventional substrate without a reflection portion 5 is used. In Comparative Example 2, the phase difference between blocks B is set to a constant value of 100 degrees. The operating frequency is 24.15 GHz.

[0067] like Figure 8 As shown, in Comparative Example 2, although reflection near the reflection direction 0 degree is suppressed compared with Comparative Example 1, large reflection occurs near ±50 degrees. In contrast, in Example 1, strong reflection in a specific direction is not generated, and reflection is suppressed in the entire reflection direction.

[0068] like Fig. 9As shown in FIG. 1 , due to the presence of the bumper, the gain variation is up to 5 dB in Comparative Example 1 and up to 2 dB in Comparative Example 2 compared to the case where the bumper is not present. In contrast, the gain variation is suppressed to a maximum of 1.5 dB in Example 1. Fig.10 As shown, the direct wave radiated from the antenna device 1 is reflected by the bumper, and the reflected wave is re-reflected by the radiation surface 2a of the antenna device 1. As a result of the interference between the re-reflected wave and the direct wave, it is radiated to the outside through the bumper. Here, the distance from the radiation surface 2a to the bumper is set to 28mm.

[0069] Fig.11 It is through Figure 8 The reflection characteristics of the reflection unit 5 including only one of the parts 51 and 52 are simulated with the same reflection intensity. In other words, the reflection characteristics are obtained when the phase difference between the blocks B is not linearly symmetrical with respect to the block center, but is continuously changed in one direction from one end to the other end in the x-axis direction. Fig.11 The chart and Fig.11 The graph after adding the graph of the left and right inverted graph is Figure 8 .

[0070] [2. Second Embodiment]

[0071] [2-1. Structure]

[0072] The antenna device 6 is used for, for example, a millimeter wave radar mounted on a vehicle and used to detect various targets existing around the vehicle.

[0073] like Fig.13 as well as Fig.14 As shown, the antenna device 6 includes a rectangular dielectric substrate 7 and a copper pattern formed on the dielectric substrate 7. Hereinafter, one side of the dielectric substrate 7 is referred to as a substrate surface 7a, and the other side is referred to as a substrate back side 7b. In addition, the direction along the longer side of the dielectric substrate 7 is referred to as the x-axis direction, the direction along the other shorter side orthogonal to the x-axis direction is referred to as the y-axis direction, and the normal direction of the substrate surface 7a is referred to as the z-axis direction.

[0074] A base plate 8 including a copper pattern covering the entire surface of the substrate back surface 7b is formed on the substrate back surface 7b. An antenna portion 9 is formed near the center in the x-axis direction on the substrate surface 7a, and additional functional portions 10 are formed on both sides in the x-axis direction across the antenna portion 9. Hereinafter, the substrate surface 7a is also referred to as a radiation surface.

[0075] The antenna unit 9 is formed of a copper pattern, and includes a rectangular patch antenna 91 and a base pattern 92 formed around the patch antenna 91. The patch antenna 91 is fed with power so that the polarization direction of the radiated radio wave coincides with the x-axis direction.

[0076] The additional functional unit 10 includes a plurality of conductor patches P including a rectangular copper pattern arranged two-dimensionally. Each of the conductor patches P is formed in a square shape, and the size of one side thereof is set to be smaller than the wavelength λ at the operating frequency of the antenna device 6. More specifically, it is desirable that the size of one side of each conductor patch P is less than 3 / 4 wavelength, and a size of about 1 / 5 to 1 / 3 wavelength is used here.

[0077] In the additional functional section 10, a plurality of columns of conductive patches P are provided along the y-axis direction. In each column, conductive patches P of the same size are arranged in a column. The conductive patches P of each column form a block B. In addition, a plurality of blocks B are arranged along the x-axis direction. In other words, the arrangement direction of the block B is consistent with the x-axis direction. The size of the conductive patches P is different in each block B. In addition, the gaps between the conductive patches P in the block B are set to a constant size that is different in each block. In addition, the gaps between the conductive patches P across adjacent blocks B are all set to a constant size.

[0078] The additional function section 10 includes two parts 11 and 12 located on both sides of the antenna section 9. The multiple blocks B and the multiple conductor patches P included in the two parts 11 and 12 have a symmetrical structure across the antenna section 9. Hereinafter, the block B closest to the antenna section 9 in each part 11 and 12 is represented as B1, and then the blocks B are represented as B2, B3, ... as they are separated from the center of the block.

[0079] In the additional functional section 10, the conductor patch P has an inductance element. In addition, the gaps between the conductor patches P have a capacitance element. In other words, in the additional functional section 10, if expressed as an equivalent circuit, Fig.14 As shown, the number of series circuits of inductance and capacitance corresponding to the number of blocks B is connected in series. Moreover, for the current flowing through the radiation surface 7a, that is, for the surface wave propagating through the radiation surface 7a, the inductance element causes a phase delay, and the capacitance element causes a phase advance.

[0080] Using this property, each block Bi in the additional functional section 10 is designed to satisfy the following conditions (4) to (6). That is, (4) the phase characteristic of the reflected wave is linearly symmetric across the block center. (5) The farther from the block center, the greater the phase delay. (6) The directivity of the surface radiation wave radiated from the additional functional section 10 is directed toward the compensation direction by the surface wave propagating along the x-axis direction on the radiation surface 7a. Among them, the direction with the minimum gain in the antenna characteristics (hereinafter referred to as basic characteristics) of the substrate without the additional functional section 5, that is, the conventional substrate, is set as the compensation direction.

[0081] Here, the additional functional portion 10 is designed by adjusting the size of the conductor patch P included in each block Bi.

[0082] [2-2. Design]

[0083] The additional function section 10 of the antenna device 6 is designed, for example, as follows.

[0084] Fig.15 It is a graph showing the reflection characteristics used in the design. Specifically, it is the phase characteristic of the reflected wave reflected by the conductor patch P for the incoming wave coming from the front direction of the antenna (hereinafter referred to as the reflection characteristic). Here, the reflection characteristic is based on the phase of the reflected wave on a substrate that does not have the additional functional portion 10, that is, a conventional substrate. In addition, the gap between the conductor patches P is fixed to 1 mm, and the size of one side of the conductor patch P is varied between 2.5 mm and 3.3 mm. That is, when the size of the conductor patch P is kept constant, the higher the operating frequency, the greater the phase delay. In addition, when the operating frequency is kept constant, the larger the size of the conductor patch P, the greater the phase delay. Fig.15 In FIG. 1 , the phase difference is shown in the range of −180 degrees to 180 degrees, so the phase difference of −180 degrees and 180 degrees are regarded as the same.

[0085] First, the size of the conductor patch P of the block Bi serving as the reference is arbitrarily determined. Fig.15 The relationship shown in FIG. 1 is used to set the size of the conductor patch P of the block Bi adjacent to the block Bi with the set size to obtain a preset phase difference at the specified operating frequency. The phase of the reflected wave obtained by this is not considered the propagation delay of the surface wave. Therefore, the phase of the surface radiation wave needs to be corrected taking into account the propagation delay of the surface wave. Next, by repeating this process in sequence, the size of the conductor patch P of all the blocks Bi is designed.

[0086] [2-3. Effect]

[0087] According to the second embodiment described in detail above, the following effects are obtained.

[0088] (2a) In the antenna device 6, the gain in the direction where the gain is the smallest in the basic characteristics is increased by utilizing the surface radiation wave radiated from the conductor patch P included in the additional function section 10 based on the surface wave propagating on the radiation surface 7a. This can improve the antenna characteristics of the antenna device 6 as a whole, and in particular, can expand the bandwidth of the antenna device 6 as a whole.

[0089] (2b) In the antenna device 6, the additional function section 10 includes the conductor patch P formed on the radiation surface 7a. Therefore, unlike the conventional technique using EBG, there is no need to provide a through hole connecting the conductor patch P and the bottom plate 8 formed on the substrate back surface 7b, so the structure of the antenna device 6 can be simplified.

[0090] (2c) In the antenna device 6, the radiation direction of the surface reflected wave is adjusted by using the phase difference between the blocks B each including a plurality of conductor patches P. Therefore, compared with the conventional technology using EBG which determines the blocking bandwidth of the surface wave by LC resonance and thus determines the usable bandwidth of the antenna, a wideband antenna can be realized.

[0091] [2-4. Experiment]

[0092] The results of simulations of Example 3 and Comparative Examples 3, 4, and 5 are described. In Example 3, the phase difference of the surface radiation wave between blocks B (hereinafter referred to as the radiation phase difference) is set to 60 degrees. In Comparative Example 3, a conventional substrate without the additional functional portion 10 is used. In Comparative Example 4, the radiation phase difference is set to 90 degrees. In Comparative Example 5, a portion having an EBG structure is provided instead of the additional functional portion 10. Among them, the operating frequency is 24.15 GHz. Fig.16 This is a table showing the radiation phase of each block with respect to Comparative Examples 3 and 4 and Example 3, with reference to block B1.

[0093] like Fig.17 As shown, Comparative Example 3 has an antenna characteristic (i.e., basic characteristic) in which the gain is minimum near the reflection azimuth of 40 to 45 degrees (hereinafter referred to as the compensation azimuth). In contrast, Example 3 has an antenna characteristic in which the bandwidth is widened and the side lobes are suppressed by improving the gain in the compensation azimuth compared to Comparative Example 3. In addition, Comparative Example 4 in which the radiation phase difference is set to a value different from that of Example 3 has an antenna characteristic in which the bandwidth is narrower and the side lobes are not suppressed even compared to Comparative Example 3. In other words, the radiation phase difference of the additional functional unit 10 needs to be appropriately optimized based on the basic characteristics.

[0094] Fig.18 This is the result of obtaining the antenna characteristics of only one of the parts 11 and 12 included in the additional function unit 10 through simulation. Fig.18 The chart and Fig.18 The graph after adding the graph of the left and right inverted graph is Fig.17 Graphs of Example 3 and Comparative Example 4 in FIG.

[0095] like Fig.19 As shown, it can be seen that Example 3 having the additional functional portion 10 can obtain antenna characteristics equivalent to or better in terms of gain and bandwidth than Comparative Example 5 using an EBG structure that is more complex than the additional functional portion 10. In other words, the same effect as that of an antenna device using an EBG structure can be achieved with a simpler structure.

[0096] [3. Other embodiments]

[0097] As mentioned above, although the form for implementing this disclosure was described, this disclosure is not limited to the above-mentioned embodiment, and can be implemented with various deformation|transformation.

[0098] (3a) In the first embodiment described above, the delay phase is adjusted by making the gap between the conductor patches P across the adjacent blocks B constant and changing the size of the conductor patches P, but the present disclosure is not limited to this. For example, the delay phase may be adjusted by providing the conductor patches P of the same size in all the blocks B and changing the gap between the conductor patches P across the adjacent blocks B. In this case, instead of Figure 3 The diagram shown in the figure is used Fig.12 The design of the reflector 5 can be performed according to the diagram shown in FIG. Fig.12 In the figure, the frequency characteristics of the phase difference relative to the conventional substrate are obtained for each case where the size of the conductor patch P is fixed at 2.9 mm × 2.9 mm and the gap between the conductor patches is changed in the range of 0.16 mm to 0.2 mm. As shown in the figure, if the operating frequency is constant, the larger the gap is, the greater the phase delay is. In addition, if the gap is constant, the higher the operating frequency is, the greater the phase delay is.

[0099] (3b) In the first embodiment, the reflector 5 is designed to satisfy conditions (1) to (3), but the present disclosure is not limited thereto. For example, as long as the reflected waves can be scattered almost equally in various directions, it is not necessary to satisfy all of the conditions (1) to (3).

[0100] (3c) In the second embodiment described above, the phases of the reflected wave and the radiated wave are adjusted by making the gaps between the conductor patches P across the adjacent blocks B constant and changing the size of the conductor patches P, but the present disclosure is not limited to this. Fig. 20 As in the antenna device 6a shown in FIG. 1 , the phases of reflected waves and radiated waves can be adjusted by providing conductor patches P of the same size in all blocks B included in the portions 11a and 12a of the additional functional portion 10a and changing the gaps between the conductor patches P across adjacent blocks B. Fig.21As shown in the antenna device 6b, the phases of the reflected wave and the radiated wave are adjusted by providing the conductor patches P having spiral patterns at the portions 11b and 12b of the additional functional portion 10b and changing the pattern width of the spiral patterns for each block B. In addition, the phases of the reflected wave and the radiated wave may be adjusted by combining these methods.

[0101] (3d) In the second embodiment described above, using Fig.15 The additional functional unit 10 is designed based on the diagram shown in FIG. 1 , but the present disclosure is not limited thereto. For example, when the phase of the reflected wave and the radiated wave is adjusted by changing the gap between the conductor patches P, the phase of the reflected wave and the radiated wave may be replaced by Fig.15 The diagram shown in the figure is used Fig. 22 The diagram shown in the figure is used to design the additional function unit 10. Fig. 22 In the figure, the frequency characteristics of the phase difference relative to the conventional substrate are obtained for each case where the size of the conductor patch P is fixed at 2.9 mm × 2.9 mm and the gap between the conductor patches is changed in the range of 0.16 mm to 0.2 mm. As shown in the figure, if the operating frequency is constant, the larger the gap is, the greater the phase delay is. In addition, if the gap is constant, the higher the operating frequency is, the greater the phase delay is.

[0102] (3e) It is also possible to implement multiple functions of a structural element in the above-mentioned embodiment by multiple structural elements, or to implement one function of a structural element by multiple structural elements. In addition, it is also possible to implement multiple functions of multiple structural elements by one structural element, or to implement one function implemented by multiple structural elements by one structural element. In addition, part of the structure of the above-mentioned embodiment may be omitted. In addition, at least part of the structure of the above-mentioned embodiment may be added to or replaced with the structure of other above-mentioned embodiments. In addition, all the methods included in the technical concept determined only by the statements recorded in the claims are embodiments of the present disclosure.

[0103] (3f) In addition to the above-mentioned antenna device, the present disclosure can be implemented in various forms such as a system that uses the antenna device as a component.

Claims

1. An antenna device, comprising: a dielectric substrate having a first side and a second side; an antenna portion disposed on the second surface of the dielectric substrate and having an antenna pattern configured to function as a radiating element; as well as an additional function unit, which is arranged around the antenna unit and has a plurality of conductor patches, each of which has a size smaller than the wavelength at a preset operating frequency, The plurality of conductor patches constituting the additional functional unit form a plurality of blocks arranged along a predetermined block arrangement direction. The additional functional section is configured to achieve a phase difference of the surface radiation wave between the blocks required to radiate the surface radiation wave from the conductor patch toward a compensation azimuth with the minimum gain in a basic characteristic, wherein the surface radiation wave from the conductor patch is caused by a surface wave propagating on the surface of the dielectric substrate, and the basic characteristic is an antenna characteristic of a conventional substrate, The direction along the longer side of the dielectric substrate is called the x-axis direction, and the direction along the other shorter side perpendicular to the x-axis direction is called the y-axis direction, then: For each of the blocks, the conductor patches have different sizes, For each of the blocks, conductor patches of the same size are arranged along the y-axis direction. By setting the gap between the conductor patches in the block in the y-axis direction to a constant size that is different for each block, the inductance component of the conductor patches and the capacitance component between the conductor patches are set. The plurality of blocks are configured such that the farther away from the block center, the more delayed the phase of the radiation wave becomes, the block center being the center of the dielectric substrate in the direction in which the blocks are arranged, and for each adjacent block, the intervals between adjacent conductor patches across the adjacent blocks are different, thereby adjusting the phase of the radiation wave, In the plurality of conductor patches, a spiral pattern having a different pattern width is provided for each of the blocks, thereby adjusting the phase of the radiation wave so that the phase delay increases more rapidly as the distance from the center of the block increases.

2. The antenna device according to claim 1, wherein: In each of the plurality of blocks, the sizes of the plurality of conductor patches are different, thereby adjusting the phase of the radiated wave.

3. The antenna device according to claim 1 or 2, wherein: The plurality of blocks are set so that the phase characteristic of the radiation wave is symmetrical across the center of the block.

4. The antenna device according to claim 3, wherein: The block arrangement direction is consistent with the polarization direction of the antenna portion.

5. The antenna device according to claim 1 or 2, wherein: Each of the plurality of conductor patches has a size of 3 / 4 wavelength or less.

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