High frequency device

Abstract

A high-frequency device is provided. A dielectric substrate (2) has a plurality of pattern layers. A ground plate (4) is formed in a first pattern layer of the dielectric substrate. A functional portion (5) has a plurality of conductor patches (50) that are unpowered patterns formed in a second pattern layer different from the first pattern layer. The conductor patches are periodically arranged, and a side along at least one direction is set to a length of resonance of an electric wave propagating on a surface of the dielectric substrate.

Description

[0001] Cross-references to related applications

[0002] This international application claims priority based on Japanese Patent Application No. 2019-208005, filed with the Japan Patent Office on November 18, 2019, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to high-frequency devices using dielectric substrates. Background Technology

[0004] Patch antennas are one type of high-frequency device that achieves various functions by forming patterns on a dielectric substrate. When such a patch antenna is used as an antenna for automotive radar, it is, for example, mounted inside a bumper. Radio waves radiated from the patch antenna and reflected by the bumper are then reflected again on the surface of the dielectric substrate on which the antenna pattern is formed, thereby interfering with the radiated waves and degrading the antenna's characteristics.

[0005] Patent document 1 describes a technique that uses a reflective array with an electromagnetic bandgap (EBG) structure to arbitrarily control the reflection direction of incident waves reflected from the front direction by the bumper, thereby suppressing the effects of reflection. The EBG structure has a structure in which multiple patches are regularly arranged and connected to a ground plane via through holes.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2014-45378

[0007] However, the inventors’ detailed research revealed the following problem: In the prior art described in Patent Document 1, it does not work on surface waves propagating on the substrate surface and cannot suppress the influence of surface waves. Summary of the Invention

[0008] In one aspect of this disclosure, a technique is provided to suppress the effects of surface waves propagating on the surface of a dielectric substrate.

[0009] One aspect of this disclosure is a high-frequency device comprising a dielectric substrate, a base plate, and a functional unit. The dielectric substrate has multiple patterned layers. The base plate is formed on a first patterned layer of the dielectric substrate and serves as a ground plane. The functional unit has multiple conductor patches, which are non-powered patterns formed on a second patterned layer of the dielectric substrate, different from the first patterned layer. The conductor patches are periodically arranged, and an edge along at least one direction is set to the length of a surface wave resonance propagating on the surface of the dielectric substrate.

[0010] With this structure, the surface wave resonates on the conductor patch belonging to the functional section, thereby increasing the propagation loss of the surface wave. As a result, radiation from the conductor patch based on the surface wave and radiation from the substrate end of the surface wave reaching the end of the dielectric substrate are suppressed, thus suppressing the influence of the surface wave. Attached Figure Description

[0011] Figure 1 This is a top view schematically showing the structure of the high-frequency device according to the first embodiment.

[0012] Figure 2 It means to Figure 1 A vertical sectional view of the section cut off by line II-II.

[0013] Figure 3 This is a vertical sectional view showing the structure of a modified high-frequency device.

[0014] Figure 4 This is a top view schematically illustrating the structure of the high-frequency device according to the second embodiment.

[0015] Figure 5 It is a graph showing the relationship between the length of the side of the conductor patch and the reflection phase at resonance.

[0016] Figure 6 This diagram illustrates the rotational effect of the conductor patch on the polarized wave.

[0017] Figure 7 This is a list of design examples of functional units that achieve a reflection phase difference of 180° and a reflection suppression effect of more than 10dB.

[0018] Figure 8 It means to Figure 7 Each of the design examples shown is illustrated with a graph showing the results of frequency characteristics of the forward transmission coefficient of the functional unit calculated through simulation.

[0019] Figure 9 This is a graph showing the results of simulation calculations of the electric field distribution in the functional part for Example 1 and Comparative Example 1, which was designed to prevent strong resonance on each side.

[0020] Figure 10 This is a top view schematically illustrating the structure of the high-frequency device according to the third embodiment.

[0021] Figure 11 This is a graph showing the results of simulation calculations of the reflection cross-sectional area for Example 2, Comparative Example 2 without a functional part, and Comparative Example 3 with a functional part but whose edge is not set to λg / 2.

[0022] Figure 12This is a graph showing the results of simulation calculations for Example 2 and Comparative Example 3, which represent the antenna characteristics as a function of gain relative to azimuth.

[0023] Figure 13 This is a diagram showing a modified example of the arrangement pattern of conductor patches constituting the functional parts.

[0024] Figure 14 This is a diagram showing a modified example of the arrangement pattern of conductor patches constituting the functional parts.

[0025] Figure 15 This is a diagram showing a modified example of the arrangement pattern of conductor patches constituting the functional parts. Detailed Implementation

[0026] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0027] [1. First Implementation Method]

[0028] [1-1. Structure]

[0029] Reference Figure 1 and Figure 2 The structure of the high-frequency device 1 in this embodiment will be described.

[0030] The high-frequency device 1 includes a dielectric substrate 2, a base plate 4, and a functional unit 5.

[0031] The dielectric substrate 2 is a rectangular plate having a thickness formed by dielectric. Hereinafter, the first surface of the dielectric substrate 2 will be referred to as the substrate surface 2a, and the second surface as the substrate back surface 2b. Both the substrate surface 2a and the substrate back surface 2b are used as patterning layers. Furthermore, the direction along one side of the rectangular dielectric substrate 2 is referred to as the X-axis direction, the direction along the side orthogonal to that side is referred to as the Y-axis direction, and the normal direction of the substrate surface 2a is referred to as the Z-axis direction. The shape of the dielectric substrate 2 is not limited to a rectangle and can be any shape.

[0032] The base plate 4 is formed as a copper pattern covering the entire surface of the back side 2b of the substrate, serving as a ground plane. In other words, the back side 2b of the substrate is equivalent to the first pattern layer.

[0033] The functional part 5 is formed on at least a portion of the substrate surface 2a and has the function of suppressing the propagation of surface waves (hereinafter, target surface waves) on the substrate surface 2a. Here, the surface waves propagate along the X-axis direction from... Figure 1 The pattern propagates from left to right. Functional unit 5 has a plurality of conductor patches 50 arranged periodically and two-dimensionally. That is, the substrate surface 2a corresponds to the second pattern layer.

[0034] All conductor patches 50 are formed as rectangular copper non-powered patterns of the same shape and size. Hereinafter, either the long side or the short side of the rectangular conductor patch 50 will be referred to as the first side, and the remaining side as the second side. Multiple conductor patches 50 are arranged at certain intervals, each insulated, with the first side along the X-axis and the second side along the Y-axis. That is, the conductor patches 50 are arranged such that the first side is along the direction of surface wave propagation. Figure 1 In this case, the long side of the rectangular conductor patch 50 is used as the first side.

[0035] For conductor patch 50, the in-tube wavelength of the surface wave is defined as λg, and the first side has a length of λg / 2. The in-tube wavelength λg is the wavelength of the surface wave that is shortened by a shortening rate corresponding to the dielectric constant of the dielectric substrate 2. However, the length of the first side does not need to be exactly λg / 2, as long as it is the resonant length of the surface wave. For example, the length of the first side can also vary within a range of about ±5% relative to λg / 2. In addition, the first side of conductor patch 20 does not need to be strictly aligned with the propagation direction of the surface wave. For example, the first side can also be tilted within a range of ±45° relative to the propagation direction of the surface wave.

[0036] [1-2. Functions]

[0037] In the high-frequency device 1 configured in this way, the surface wave propagating along the X-axis direction on the substrate surface 2a resonates at the first side of each conductor patch 50 in the functional section 5, which has a length of λg / 2, along the X-axis direction. At this resonance, the surface wave is subjected to resistive losses in the conductor patch 50 and dielectric losses in the dielectric substrate 2.

[0038] [1-3. Effects]

[0039] According to the first embodiment described in detail above, the following effects are achieved.

[0040] (1a) In the high-frequency device 1, the surface wave propagating on the substrate surface 2a is lost due to resonance on the conductor patch 50 belonging to the functional section 5. As a result, radiation from the conductor patch 50 based on the surface wave and radiation from the substrate end of the surface wave reaching the end of the dielectric substrate 2 can be suppressed. In other words, not only can the surface wave suppression effect of suppressing the propagation of the surface wave be obtained, but also the radiation suppression effect of suppressing the radiation from the conductor patch 50 based on the surface wave can be obtained.

[0041] (1b) When a surface wave generator and other circuits are provided on the dielectric substrate 2, the influence of the surface wave on the other circuits can be suppressed by providing the functional part 5 between the generator and other circuits.

[0042] [1-4. Variations]

[0043] In the high-frequency device 1 of the first embodiment, a dielectric substrate 2 with patterned layers on the substrate surface 2a and the substrate back surface 2b is used, but the structure of the dielectric substrate is not limited to this. For example, it can also be like... Figure 3 As shown in the high-frequency device 1a, a multilayer dielectric substrate 3 is used, which has a patterned layer in the inner layer 3c of the substrate in addition to the substrate surface 3a and the substrate back surface 3b. In this case, the functional part 5 can also be formed in the inner layer 3c of the substrate. However, the functional part 5 is formed in a patterned layer that is adjacent to the patterned layer on which the base plate 4 is formed, separated by the dielectric layer. Furthermore, the pattern 41 formed on the substrate surface 3a can be a pattern that functions as a ground plane or a pattern that functions as a high-frequency circuit.

[0044] [2. Second Implementation]

[0045] [2-1. Differences from the first embodiment]

[0046] Since the basic structure of the second embodiment is the same as that of the first embodiment, the differences will be described below. Furthermore, the same reference numerals as in the first embodiment denote the same structures, as described previously.

[0047] In the high-frequency device 1 of the first embodiment described above, the conductor patch 50, belonging to the functional unit 5, is arranged such that its first edge is aligned along the X-axis direction (i.e., the propagation direction of the surface wave). In the high-frequency device 1b of the second embodiment, as... Figure 4 As shown, the first and second sides of the conductor patch 60 belonging to the functional part 6 are both configured to be tilted 45° in opposite directions relative to the X-axis direction.

[0048] Hereinafter, the direction along the first side of the conductor patch 60 will be referred to as the α direction, and the direction along the second side will be referred to as the β direction. The α direction and the β direction are orthogonal to each other. The length Lα of the first side of the conductor patch 60 along the α direction and the length Lβ of the second side along the β direction are different.

[0049] Multiple conductor patches 60 are insulated, all tilted at the same angle, and arranged at certain intervals in the α and β directions.

[0050] In the conductor patch 60, the length Lα of the first side is set to λg / 2. The length Lβ of the second side is set such that, relative to the surface wave resonance, the phase difference Δθ between the signal resonating on the second side and the signal resonating on the first side (hereinafter, the phase difference at resonance) becomes opposite (i.e., the phase difference is 180°).

[0051] like Figure 5 As shown, the lengths Lα and Lβ of each side of the conductor patch 60 are correlated with the phase of the signal resonating at each side. Using this relationship, the lengths Lα and Lβ of each side of the conductor patch 60 are set such that the phase difference Δθ at resonance is 180°.

[0052] [2-2. Action]

[0053] The case where the surface wave is a horizontally polarized wave with its polarization plane along the X-axis will be explained. The α and β directions are inclined at angles of 45° relative to the polarization plane of the surface wave. When the surface wave propagates, the current excited by the surface wave flows along the first and second sides of the conductor patch 60, resonating in both the α and β directions. Since the lengths Lα and Lβ of the first and second sides are different, the resonant lengths in the two directions are different. As a result, a phase difference occurs between the phase of the signal resonating on the first side and the phase resonating on the second side, i.e., Δθ ≠ 0°. Therefore, the polarization direction of the emitted wave from the conductor patch 60 is different from that of the surface wave.

[0054] In particular, when Δθ = 180°, the radiated wave emitted from the conductor patch 60 excited by the surface wave of the object is as follows: Figure 6 As shown, the horizontally polarized wave along the X-axis of the object surface wave changes to a vertically polarized wave along the Y-axis. As a result, interference from electromagnetic waves with the same horizontal polarization as the object surface wave and from radiated waves from the conductor patch 60 with vertical polarization can be suppressed.

[0055] Here, Figure 7 This represents a combination of parameters that, by varying the lengths Lα and Lβ of each side of the conductor patch 60 and the arrangement interval g of the conductor patches 60, suppress radiation from the conductor patch 60 to a level greater than 10 dB. Specifically, Lα is varied within a range of λg / 2 ± 5%, and Lβ and g are calculated through simulation. Figure 8 Yes Figure 7 The propagation characteristics of surface waves were calculated through simulation for each of the parameter combination modes 1 to 5 shown. Using the parameter combination shown as mode 4, it was found that both radiation suppression and surface wave suppression effects exceeded 10 dB in the 76 GHz to 77 GHz range.

[0056] Figure 9The results of electric field distribution calculations for Example 1 and Comparative Example 1 are shown. Example 1 is a high-frequency device 1b designed to achieve both surface wave suppression and reflection suppression effects. Comparative Example 1 is a high-frequency device designed such that the first and second sides of the conductor patch 60 differ from λg / 2 by more than 5%, i.e., strong resonance does not occur on any side.

[0057] exist Figure 9 In the diagram, the shaded areas represent the locations where strong electric field strength was observed. In Example 1, it is known that resonance occurs along the α direction of the first side of each conductor patch 60, resulting in a strong electric field at both ends of the α direction. Furthermore, through resonance, the propagation of surface waves is suppressed, thereby reducing the intensity of the electric field emitted from the conductor patch 60.

[0058] In Comparative Example 1, it can be seen that since no strong resonance occurs in the conductor patch 60, the surface wave propagates with a strong intensity, and thus the intensity of the electric field radiated from each conductor patch 60 also becomes stronger.

[0059] [2-3. Effects]

[0060] According to the second embodiment described in detail above, the effects of the first embodiment (1a) and (1b) described above are achieved, and the following effects are achieved.

[0061] (2a) In the high-frequency device 1b, the radiation wave from the conductor patch 60 based on the object surface wave is converted to have a polarization surface different from the object surface wave, thus further suppressing the electromagnetic interference between the radiation wave and the horizontally polarized wave with the same polarization as the object surface wave.

[0062] [3. Third Implementation Method]

[0063] [3-1. Differences from the second embodiment]

[0064] Since the basic structure of the third embodiment is the same as that of the second embodiment, the differences will be described below. Furthermore, the same reference numerals as in the first and second embodiments denote the same structures, as described previously.

[0065] In the high-frequency device 1b of the second embodiment described above, a functional part 6 is provided on the substrate surface 2a. In the high-frequency device 1c of the third embodiment, as... Figure 10 As shown, the point where an antenna part 7 is provided on the substrate surface 2a in addition to the functional part 6 is different from that in the second embodiment.

[0066] High-frequency device 1c is used, for example, as an antenna device in millimeter-wave radar for detecting various objects present around a vehicle.

[0067] The antenna section 7 has one or more antenna patterns that function as radiating elements that radiate radio waves at a predetermined operating frequency.

[0068] In the high-frequency device 1c, the antenna section 7 is disposed near the center of the substrate surface 2a. Functional sections 6 are formed around the antenna section 7 in three directions, excluding the direction in which power supply lines are routed to the antenna section 7. Figure 10 In the antenna section 7, functional sections 6 are formed in the direction above and to the left and right, except for the bottom.

[0069] The antenna section 7 has a polarization surface along the X-axis direction in the figure, and transmits a linearly polarized wave (hereinafter, a horizontally polarized wave) with a wavelength of λg inside the tube.

[0070] [3-2. Experiment]

[0071] The results of measuring the radar cross-section (RCS) of the high-frequency device 1c (hereinafter, Embodiment 2) having functional part 6 are shown below. Figure 11 As a comparative example 2, the RCS of a simple metal plate without functional part 6 is also shown.

[0072] In the high-frequency device 1c (i.e., Embodiment 2), it can be seen that due to the presence of the functional unit 6, the RCS outside the front direction is suppressed to a sufficiently small value compared to Comparative Example 2. Furthermore, in Comparative Example 3, which has a similar structure to the functional unit 6, but the lengths Lα and Lβ of the sides of the conductor patch 60 are both set to the non-resonant length of the radio waves transmitted by the antenna unit 7, the same measurement results as in Embodiment 2 can also be obtained.

[0073] The antenna characteristics of Example 2 and Comparative Example 3 are shown below. Figure 12 .

[0074] In Comparative Example 3, the influence of surface wave-based radiation from the conductor patch 60 on the characteristics of the antenna section 7 due to the rotation of the polarization surface is suppressed. However, surface wave-based radiation from the substrate end becomes interference waves against the radiation waves from the antenna section 7, affecting the antenna characteristics; specifically, the gain varies significantly depending on the azimuth. In Example 2, by resonating the surface wave in the conductor patch 60, the propagation of the surface wave from the antenna section 7 to the substrate end is suppressed, and the gain variation is suppressed by reducing radiation from the substrate end (i.e., interference waves).

[0075] [3-3. Effect]

[0076] According to the third embodiment described in detail above, the effects of the first and second embodiments described above (1a)(1b)(2a) are achieved, and the following effects are achieved.

[0077] (3a) In the high-frequency device 1c, the functional unit 6 disposed between the antenna section 7 and the substrate end reduces the propagation of surface waves generated by the antenna section 7 and the substrate end radiation based on the surface waves. As a result, the disturbance of antenna characteristics caused by interference from the substrate end radiation is suppressed, thereby improving antenna performance.

[0078] Furthermore, the substrate end radiation has the effect of expanding the angular range in which the desired gain is obtained in the antenna characteristics, so the propagation characteristics of the functional part 6 can also be designed to obtain the required substrate end radiation.

[0079] [4. Other Implementation Methods]

[0080] The embodiments of this disclosure have been described above, but this disclosure is not limited to the above embodiments and can be implemented in various ways.

[0081] (4a) In the above embodiment, the conductor patches 50, 50 constituting the functional parts 5, 5 are as follows: Figure 1 as well as Figure 4 As shown, the first and second sides of the rectangle are arranged in a row, but the arrangement of the conductor patches is not limited to this. For example, Figure 13 As shown, the rectangular conductor patch 60 can also be configured such that only one of the first and second sides is arranged in a row.

[0082] (4b) In the above embodiments, rectangular conductor patches 50, 50 are used, but the shape of the conductor patches is not limited to this. For example, rectangular conductor patches may also be used. Figure 14 The hexagonal conductor patch 61 shown and as Figure 15 The octagonal conductor patch 62 shown is an arbitrary polygonal conductor patch.

[0083] (4c) Multiple functions of one component in the above embodiments can be achieved through multiple components, or one function of one component can be achieved through multiple components. Alternatively, multiple functions of multiple components can be achieved through one component, or one function achieved by multiple components can be achieved through one component. Furthermore, a portion of the structure in the above embodiments can be omitted. Additionally, at least a portion of the structure in other above embodiments can be added to or replaced.

[0084] (4d) In addition to the high-frequency devices 1, 1a to 1c described above, this disclosure can also be implemented in various ways, such as a system in which the high-frequency devices 1, 1a to 1c are used as constituent elements, or an unnecessary radiation suppression method.

Claims

1. A high-frequency device, comprising: A dielectric substrate having multiple patterned layers; A base plate, formed on the first patterned layer of the aforementioned dielectric substrate, is used as a ground plane; and The functional unit has multiple conductor patches, which are non-powered patterns formed on a second pattern layer of the dielectric substrate that is different from the first pattern layer. The aforementioned conductor patches are periodically arranged, and their edges along at least one specified direction are set to the length of the resonance of the electromagnetic wave propagating on the surface of the aforementioned dielectric substrate. The edge of the conductor patch, which is set to the length of the aforementioned radio wave resonance, has a length within the range of 1 / 2 ± 5% of the in-tube wavelength of the aforementioned radio wave. The arrangement spacing of the conductor patches is set based on the length of at least one side of the conductor patch within a range of 1 / 2 ± 5% of the wavelength of the aforementioned radio wave within the tube. The wavelength within the tube described above is the wavelength of an electromagnetic wave that is shortened by a shortening rate corresponding to the dielectric constant of the dielectric substrate described above. The first and second sides of the aforementioned conductor patch intersect each other. The length of the second side of the conductor patch and the arrangement interval of the conductor patch are set based on the length of the first side within 1 / 2 ± 5% of the wavelength of the aforementioned radio wave, so that radiation from the conductor patch is suppressed by more than 10 dB.

2. The high-frequency device according to claim 1, wherein, The aforementioned conductor patch is a polygon, and the arrangement is periodically arranged along the direction of one or more of the sides of the polygon.

3. The high-frequency device according to claim 2, wherein, The aforementioned conductor patch is rectangular, with two directions along each of the two orthogonal sides serving as the aforementioned arrangement direction.

4. The high-frequency device according to any one of claims 1 to 3, wherein, The aforementioned dielectric substrate has three or more patterned layers. The aforementioned functional part is formed on a patterned layer sandwiched between two dielectric layers on the inner side.

5. The high-frequency device according to any one of claims 1 to 3, wherein, An antenna portion is formed in the second pattern layer, and the antenna portion has one or more antenna patterns that function as radiating elements. The aforementioned plurality of conductor patches are disposed between the ends of the antenna portion and the dielectric substrate.

6. The high-frequency device according to any one of claims 1 to 3, wherein, An antenna portion is formed in the second pattern layer, and the antenna portion has one or more antenna patterns that function as radiating elements and radiate linearly polarized waves. The aforementioned plurality of conductor patches are configured to generate radiation waves with opposite phase to the incident wave having the operating frequency of the aforementioned antenna in two directions inclined relative to the polarization wave direction of the radiated radio wave emitted from the aforementioned antenna section.

7. The high-frequency device according to claim 6, wherein, The aforementioned conductor patch has two sides that are tilted at 45° to each other in opposite directions relative to the polarization wave direction of the aforementioned radiated electromagnetic wave.

8. The high-frequency device according to any one of claims 1 to 3, wherein, An antenna portion is formed in the second pattern layer, and the antenna portion has one or more antenna patterns that function as radiating elements and radiate linearly polarized waves. The antenna portion is disposed near the center of the surface of the dielectric substrate, and the functional portion is formed around the antenna portion in three directions other than the direction in which the power supply line for the antenna portion is arranged.

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