Reflectarray

Abstract

Provided is a reflectarray capable of adjusting a reflection phase to three or more values and having a simple configuration.　The reflectarray includes a plurality of cells and can set a reflection angle of radio waves at an angle other than specular reflection. Each of the plurality of cells includes a first main resonance element, a second main resonance element, a first parasitic resonance portion provided between the first main resonance element and the second main resonance element, and a second parasitic resonance portion provided between the first main resonance element and the second main resonance element. Each of the plurality of cells can adjust a reflection phase to three or more values by adjusting a resonance frequency.

Description

Reflectarray

[0001] The present disclosure relates to a reflectarray.

[0002] Conventionally, there has been a reflectarray antenna element that includes a rectangular patch made of a conductive material for reflecting an electromagnetic field, first to fourth phase control lines connected between first to fourth sides of the patch and ground, respectively, and first to fourth switching devices inserted in series into the first to fourth phase control lines, and that controls the amount of phase shift of the reflected wave by selectively switching the first to fourth switching devices on and off (see, for example, Patent Document 1).

[0003] Special Publication No. 2021-530164

[0004] Incidentally, a conventional reflectarray antenna element (reflectarray) uses four switching devices (switching elements) for one patch (resonant element), resulting in a large number of parts and a complex configuration.

[0005] Therefore, an object of the present invention is to provide a reflectarray that can adjust the reflection phase to three or more values ​​and has a simple configuration.

[0006] A reflectarray according to an embodiment of the present disclosure is a reflectarray that includes a plurality of cells and is capable of setting the reflection angle of radio waves to an angle other than specular reflection, wherein each of the plurality of cells includes a first main resonance element, a second main resonance element, a first parasitic resonance part provided between the first main resonance element and the second main resonance element, and a second parasitic resonance part provided between the first main resonance element and the second main resonance element, and the reflection phase of each of the plurality of cells can be adjusted to three or more values ​​by adjusting the resonance frequency.

[0007] It is possible to provide a reflectarray with a simple configuration in which the reflection phase can be adjusted to three or more values.

[0008] 1 is an explanatory diagram of the operation of the radio wave transmission system 10 according to the first embodiment of the present disclosure. FIG. 2 is a block diagram showing an example of the configuration of the radio wave transmission system 10. FIG. 3 is a diagram showing an example of a state in which the radio wave transmission system 10 is attached to a wall 1. FIG. 4 is a diagram showing an example of an arrangement of a plurality of cells of the reflect array 100. FIG. 5 is a diagram showing an example of the details of the configuration of the cell 100A. FIG. 6 is a diagram showing an example of the results of a simulation (part 1) of the reflection phase of the reflect array 100. FIG. 7 is a diagram showing an example of the results of a simulation (part 2) of the reflection phase of the reflect array 100. FIG. 8 is a diagram showing an example of the results of a simulation of the reflection characteristics of a comparative binary-controlled reflect array. FIG. 9 is a diagram showing an example of the results of a simulation of the reflection characteristics of the reflect array 100. FIG. 10 is a diagram showing an example of the details of the configuration of a cell 200A according to the second embodiment. FIG. 11 is a diagram showing an example of the results of a simulation of the reflection phase of the reflect array according to the second embodiment.

[0009] Hereinafter, embodiments to which the radio wave transmission system and reflectarray of the present disclosure are applied will be described. In the following, the same elements will be denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0010] In the following description, the XYZ coordinate system is defined. The direction parallel to the X axis (X direction), the direction parallel to the Y axis (Y direction), and the direction parallel to the Z axis (Z direction) are perpendicular to one another. For ease of explanation, the -Z direction may be referred to as the lower side or bottom, and the +Z direction may be referred to as the upper side or top. Planar view refers to viewing from the XY plane. In the following description, the length, width, thickness, etc. of each part may be exaggerated to make the configuration easier to understand. Terms such as parallel, right angle, orthogonal, horizontal, vertical, and up and down may be misaligned to the extent that they do not impair the effects of the embodiments.

[0011] In the following description, "radio waves" refers to a type of electromagnetic wave, and generally, electromagnetic waves of 3 THz or less are called radio waves. In the following, electromagnetic waves emitted from an outdoor base station or relay station will be referred to as "radio waves," and electromagnetic waves in general will be referred to as "electromagnetic waves." In the following, "millimeter waves" will include, as an example, the frequency band of 30 GHz to 300 GHz as well as the quasi-millimeter wave band of 24 GHz to 30 GHz.

[0012] The radio waves reflected by the reflector included in the radio wave transmission system of the embodiment are preferably in the millimeter wave band of the fifth generation mobile communication system (5G) or in the frequency band of 1 GHz to 30 GHz including Sub-6. Furthermore, the radio waves reflected by the reflector included in the radio wave transmission system of the embodiment may be LTE (Long Term Evolution), LTE-Advanced (LTE-A), or UMB (Ultra Mobile Broadband). Furthermore, the radio waves reflected by the reflector included in the radio wave transmission system of the embodiment may be IEEE 802.11 (Wi-Fi (registered trademark)), IEEE 802.16 (WiMAX (registered trademark)), IEEE 802.20, UWB (Ultra-Wideband), Bluetooth (registered trademark), LPWA (Low Power Wide Area), or the like. As the frequency of the radio waves increases, propagation loss due to reflection and diffraction increases, making blind zones more likely to occur. Therefore, the reflector included in the radio wave transmission system of the embodiment is more suitable for communications using relatively high frequencies.Unless otherwise specified, the following description will be given using millimeter wave band and Sub-6 radio waves as examples.

[0013] First Embodiment Radio Wave Transmission System 10 FIG. 1 is a diagram illustrating the operation of a radio wave transmission system 10 according to a first embodiment of the present disclosure.

[0014] The radio wave transmission system 10 is disposed, for example, on a wall or a window of an outdoor building BD. The radio wave transmission system 10 has a reflectarray 100 (see FIG. 2 ), and the reflectarray 100 of the present disclosure is a directivity control array called a RIS (Reconfigurable Intelligent Surface) that is capable of adjusting the directivity of a beam.

[0015] The type of building BD in which the radio wave transmission system 10 is installed is arbitrary, but may be, for example, a building in an area where high-rise buildings stand side by side. In areas where high-rise buildings stand side by side, dead zones (areas or spaces with poor communication environments, also called "dead zones") where radio waves do not reach properly are likely to occur. The radio wave transmission system 10 of the present disclosure delivers radio waves to dead zones by controlling the direction of the reflected radio wave beam.

[0016] FIG. 1 schematically illustrates the radiation patterns of radio waves transmitted from a radio base station BS and radio waves R reflected from a radio wave transmission system 10. As shown in FIG. 1, a radio base station BS may be provided for wireless communication. The radio base station BS converts signals from a network (not shown) such as the Internet into radio signals and transmits the radio waves R, which are then received by a receiving terminal. The radio base station BS also receives the radio waves R transmitted by the receiving terminal, allowing the receiving terminal to access a network such as the Internet. The radio base station BS may be provided near the radio wave transmission system 10, approximately several tens of centimeters to several meters, or may be provided at a distance of approximately several tens of meters to several kilometers from the radio wave transmission system 10.

[0017] The radio wave transmission system 10 of the present disclosure delivers radio waves to blind areas blocked by buildings BD by changing the beam direction of the incident radio waves R and reflecting the beam in a specific direction or by generating multiple beams. In the following description, the radio waves are assumed to be plane waves unless otherwise specified.

[0018] As shown in FIG. 1 , the use of a radio wave transmission system 10 enables Internet communication by selecting an outdoor receiving terminal U1, U2, or U3. Specifically, for example, radio waves R transmitted from a radio base station BS at a certain time are reflected by the radio wave transmission system 10 and received by the outdoor receiving terminal U1, thereby establishing wireless communication with the receiving terminal U1. Radio waves R transmitted from the radio base station BS at a different time are reflected by the radio wave transmission system 10 and received by the outdoor receiving terminal U2, thereby establishing wireless communication with the receiving terminal U2. The same applies to the receiving terminal U3 as to the receiving terminals U1 and U2. Note that, although the case where the receiving terminals U1, U2, and U3 receive radio waves R will be described here, when the receiving terminals U1, U2, and U3 transmit radio waves R, the radio base station BS receives the radio waves R reflected by the radio wave transmission system 10.

[0019] 1 shows, as an example, a radio wave transmission system 10 in addition to a configuration in which radio waves coming from a radio base station BS are reflected by the reflect array 100, but radio waves coming from a radio relay station or the like may also be reflected by the reflect array 100. Also, in FIG. 1, the receiving terminals U1, U2, and U3 are smartphones carried by users, but they may also be fixed receiving terminals that are fixed to a building or the like and do not move.

[0020] Fig. 2 is a block diagram showing an example of the configuration of the radio wave transmission system 10. Fig. 3 is a diagram showing an example of the radio wave transmission system 10 attached to a wall 1. Fig. 2 shows a state in which the reflect array 100 directly reflects radio waves arriving from a radio base station BS toward a receiving terminal U1. The receiving terminal U1 has an antenna for communication.

[0021] The radio wave transmission system 10 includes a reflectarray 100 and a control unit 5. The radio wave transmission method of the first embodiment is realized by processing executed by the control unit 5 of the radio wave transmission system 10. A control command is input to the control unit 5 from an external device. The control command is a control command for controlling multiple phase change amounts that change the phase of radio waves when multiple cells of the reflectarray 100 reflect the radio waves.

[0022] The control unit 5 is realized by, for example, an MCU (Micro Controller Unit), and includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an input / output interface, an internal bus, etc. Based on a control command, the control unit 5 controls multiple phase change amounts that change the phase of radio waves when multiple cells of the reflectarray 100 reflect the radio waves. The control unit 5 operates based on a power supply voltage generated by a power supply generation unit (not shown).

[0023] When the radio waves reflected by the reflect array 100 are radio waves in the frequency band of 24 GHz to 300 GHz in the millimeter wave band such as (5G), the radio waves used for communication between the user terminal U1 and the radio base station BS may be, for example, LTE, LTE-A, UMB, IEEE802.11 (Wi-Fi (registered trademark)), IEEE802.16 (WiMAX (registered trademark)), IEEE802.20, UWB, Bluetooth (registered trademark), or LPWA.

[0024] 3, the radio wave transmission system 10 (the reflect array 100 and the control unit 5) is provided on the wall 1. Here, when the radio wave transmission system 10 is provided on the wall 1 of the building BD, the height from the ground is preferably 1 m to 14 m, and particularly preferably 2 m to 10 m, from the viewpoint of radio wave efficiency.

[0025] 3 shows an example in which the radio wave transmission system 10 is disposed on a wall 1, but the reflectarray 100 in the radio wave transmission system 10 may be disposed on the main surface of a window glass. When the reflectarray 100 is disposed on a window glass, it is preferable that the substrate of the reflector and the resonant elements included in the reflectarray 100 are made of a transparent material having a luminous transmittance of 50% or more. When the reflectarray 100 is disposed on a window glass, the control unit 5 may be disposed away from the reflectarray 100 and in another location, such as a wall portion adjacent to the window glass or a frame portion of the window glass.

[0026] Furthermore, the radio wave transmission system 10 of the present disclosure may be installed on an indoor wall or window glass. In this case, it contributes to reducing blind zones indoors. When the radio wave transmission system 10 is installed indoors, the height from the floor is preferably 0.5 m to 3 m, and particularly preferably 1 m to 2 m, from the viewpoint of radio wave efficiency.

[0027] <Configuration of Reflect Array 100> Next, the configuration of the reflect array 100 will be described with reference to FIG.

[0028] Fig. 4 is a diagram showing an example of an arrangement of multiple cells of the reflectarray 100. Fig. 4 shows the reflectarray 100 that reflects horizontally polarized radio waves, but if the reflectarray 100 shown in Fig. 4 is rotated 90 degrees clockwise or counterclockwise in a plan view, a reflectarray 100 that reflects vertically polarized radio waves can be obtained.

[0029] As shown in Fig. 4, the reflect array 100 has a substrate 101 and a plurality of cells 100A regularly arranged on the surface on the +Z direction side of the substrate 101. The cells 100A are configured as repeating units, and for example, in Fig. 4, as an example, three cells 100A are arranged in the X direction and six cells 100A are arranged in the Y direction. Details of the substrate 101 and the cells 100A will be described later using Fig. 5.

[0030] The reflect array 100 can adjust the reflection angle of the radio waves reflected by the reflect array 100 to an angle other than specular reflection or to the angle of specular reflection by controlling the amount of phase change (phase change amount) when the radio waves are reflected by each cell 100A. As an example, as shown in Fig. 4, the reflection angle of the reflected wave can be adjusted by arranging multiple cells 100A in the X direction and the Y direction.

[0031] The amount of phase change of each cell 100A of the reflectarray 100 can be controlled to three or more values, for example. The reflectarray 100 reflects radio waves in a desired reflection direction by controlling the amount of phase change of each cell 100A and adjusting the reflection angle when the reflectarray 100 reflects radio waves. Control of the amount of phase change of each cell 100A is achieved by changing the resonant frequency of each cell 100A. In other words, each cell can adjust the reflection phase to three or more values ​​by adjusting the resonant frequency. The reflection phase is the phase of the reflected wave. The fact that the reflection phase can be adjusted by adjusting the resonant frequency is described in International Publication No. 2023 / 282299.

[0032] Here, the reflection phase of each cell is the phase of the reflected wave that is generated when the radio wave (incident wave) that enters each cell is reflected by that cell. The reflection phase of the reflected wave that each cell reflects is adjusted by adjusting the amount of phase change that each cell imparts to the incident wave. The amount of phase change is the amount by which the phase of the radio wave that enters each cell changes when it is reflected.

[0033] The overall phase change amount of the reflect array 100 is the phase change amount of a reflected wave obtained by combining a plurality of reflected waves that have been given phase changes relative to an incident wave by a plurality of cells included in the reflect array 100. The overall reflection phase of the reflect array 100 is the reflection phase of a reflected wave obtained by combining a plurality of reflected waves that have been reflected from an incident wave by a plurality of cells included in the reflect array 100.

[0034] The arrangement of the multiple cells 100A is not limited to the array shown in Fig. 4, and may be, for example, randomly (irregularly) arranged without any regularity. The number of cells 100A arranged in the X direction and the Y direction may be even larger, and as an example, 10 or more cells may be arranged in the X direction and the Y direction. The number of cells 100A arranged in the X direction and the Y direction is preferably 130 or less, and more preferably 100 or less.

[0035] <Detailed Configuration of Cell 100A and Substrate 101> Fig. 5A is a diagram showing an example of the detailed configuration of the cell 100A. First, the substrate 101 will be described. Fig. 5A shows a portion of the entire substrate 101 that corresponds to one cell 100A.

[0036] The substrate 101 is, for example, a rectangular substrate in a planar view. The substrate 101 may be, for example, a flexible substrate made of a thin film of resin, or a rigid substrate that is not flexible. Flexibility refers to the ability of an object to bend without breaking to an extent that is visible from the outside. If the substrate 101 is a flexible substrate, it may be made of a flexible resin material such as fluorine, COP (Cyclo-Olefin Polymer), PET (Polyethylene terephthalate), PEN (Polyethylene naphthalate), polyimide, Peek (Polyether ether ketone), LCP (Liquid Crystal Polymer), or other composite materials. If the substrate 101 is a rigid substrate, it may be made of, for example, a substrate formed by bonding a core material to a prepreg made of glass cloth impregnated with epoxy resin or the like.

[0037] Furthermore, the substrate 101 may be formed of any material that is transparent to radio waves radiated from an outdoor radio base station BS or the like. "Transparent to the radiated radio waves" means, for example, that the transmission loss is 10 dB or less. "Substrate 101 is transparent to the radiated radio waves" means that the transmission loss of the substrate 101 is 10 dB or less, preferably 6 dB or less, more preferably 3 dB or less, and even more preferably 1 dB or less.

[0038] The substrate 101 may be transparent to visible light. "Transparent" to visible light means that the luminous transmittance is at least 40% or more, preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more.

[0039] As an example, a resin substrate (resin film) may be used as the substrate 101. Examples of resin materials that satisfy the above conditions include acrylic resins such as polymethyl methacrylate, cycloolefin resins, polycarbonate resins, and polyethylene terephthalate (PET). Alternatively, a glass plate may be used as the substrate 101. Examples of glass plates that satisfy the above conditions include soda-lime glass, alkali-free glass, Pyrex (registered trademark) glass, and quartz glass.

[0040] The substrate 101 may be formed of a material that reflects radio waves emitted from an outdoor wireless base station BS or the like with low loss. Reflecting with low loss means, for example, that the reflection loss is 1.0 dB or less. For example, reflecting with low loss means that the reflection loss is 1.0 dB or less, preferably 0.6 dB or less, more preferably 0.3 dB or less, and even more preferably 0.1 dB or less.

[0041] As an example, a resin substrate having a dielectric loss tangent of 0.01 or less may be used as the substrate 101. Examples of resin substrates that satisfy the above conditions include Megtron 6 and Meteorwave 8000.

[0042] <Cell 100A> The cell 100A has a first main resonance element 110A, a first parasitic resonance unit 120A, a second main resonance element 110B, and a second parasitic resonance unit 120B. The first parasitic resonance unit 120A has a first parasitic resonance element 121, a second parasitic resonance element 122, and a first switching element 125A. The second parasitic resonance unit 120B has a third parasitic resonance element 123, a fourth parasitic resonance element 124, and a second switching element 125B. The first parasitic resonance unit 120A is provided between the first main resonance element 110A and the second main resonance element 110B, and the second parasitic resonance unit 120B is provided between the first main resonance element 110A and the second main resonance element 110B.

[0043] The first parasitic resonator element 121, the second parasitic resonator element 122, the third parasitic resonator element 123, and the fourth parasitic resonator element 124 are formed of metal layers. When the substrate 101 is not formed of any material that is transparent to visible light, the metal layers can be formed of a metal thin film such as copper, nickel, or gold. When the substrate 101 is formed of any material that is transparent to visible light, the metal layers can be formed of a metal thin film such as zinc oxide (ZnO), tin oxide (SnO ２ The metal layer is preferably formed of a transparent conductive film such as tin-doped indium oxide (ITO) or indium oxide-tin oxide (IZO), a metal nitride such as titanium nitride (TiN) or chromium nitride (CrN), or a low-e film for low-e (low emissivity) glass. Furthermore, when the substrate 101 is formed of any material that is transparent to visible light, the metal layer may be formed of a mesh-like metal thin film such as copper, nickel, or gold.

[0044] Here, as an example, a configuration will be described in which the first main resonance element 110A and the second main resonance element 110B are both square in plan view, but the planar shapes of the first main resonance element 110A and the second main resonance element 110B may be other than square, such as rectangular, triangular, circular, or elliptical.

[0045] Further, as an example, the first main resonance element 110A and the second main resonance element 110B have the same shape and the same size in a plan view, but the sizes in a plan view may be different.

[0046] Additionally, as an example, a configuration will be described in which the first parasitic resonator element 121, the second parasitic resonator element 122, the third parasitic resonator element 123, and the fourth parasitic resonator element 124 are all H-shaped in a planar view. However, the planar shapes of these resonator elements do not have to be H-shaped. For example, the planar shapes of these resonator elements may be linear, elongated in the Y direction, or may have other shapes. Furthermore, the planar shape of at least one of these resonator elements may be different from the others. Note that "having the same planar shape" includes shapes that are similar but different in size. Details of the sizes of the first parasitic resonator element 121, the second parasitic resonator element 122, the third parasitic resonator element 123, and the fourth parasitic resonator element 124 will be described later.

[0047] <First main resonator element 110A> The first main resonator element 110A is, for example, a conductor having a square shape in a plan view. The first main resonator element 110A has an end side 111A extending along the Y direction on the +X direction side. A first parasitic resonator element 121 and a third parasitic resonator element 123 are provided adjacent to the end side 111A on the +X direction side, and the second parasitic resonator element 122 and a fourth parasitic resonator element 124 are provided adjacent to the first parasitic resonator element 121 and the third parasitic resonator element 123 on the +X direction side.

[0048] A first switching element 125A that can switch between a conductive state and a non-conductive state is connected between the first parasitic resonant element 121 and the second parasitic resonant element 122. The first switching element 125A can switch the connection state between the first parasitic resonant element 121 and the second parasitic resonant element 122. The connection state is either an electrically connected state (conductive state) or an electrically disconnected state (non-conductive state).

[0049] A second switching element 125B that can switch between a conductive state and a non-conductive state is connected between the third parasitic resonator element 123 and the fourth parasitic resonator element 124. The second switching element 125B can switch the connection state between the third parasitic resonator element 123 and the fourth parasitic resonator element 124. The meaning of the connection state is as described above.

[0050] When the first switching element 125A and the second switching element 125B are both in a non-conducting state, the first parasitic resonator element 121 and the third parasitic resonator element 123 are coupled to and parasitize the first main resonator element 110A by electromagnetic field coupling. Hereinafter, "a resonant element parasitizing another resonant element" refers to "a resonant element being coupled to and parasitizing another resonant element by electromagnetic field coupling."

[0051] When the first switching element 125A is in a conductive state and the second switching element 125B is in a non-conductive state, the first main resonator 110A is parasitic with the first parasitic resonator 121 and the second parasitic resonator 122, as well as the third parasitic resonator 123.

[0052] When the first switching element 125A is in a non-conductive state and the second switching element 125B is in a conductive state, the first main resonance element 110A is parasitic with a first parasitic resonance element 121, and is also parasitic with a third parasitic resonance element 123 and a fourth parasitic resonance element 124. When the first switching element 125A and the second switching element 125B are both in a conductive state, the first main resonance element 110A is parasitic with the first parasitic resonance element 121 and the second parasitic resonance element 122, and is also parasitic with the third parasitic resonance element 123 and the fourth parasitic resonance element 124.

[0053] <Second main resonance element 110B> The second main resonance element 110B is, for example, a conductor that is square in plan view, and has, for example, the same shape and size as the first main resonance element 110A. The second main resonance element 110B is provided on the +X direction side of the first main resonance element 110A, and a first parasitic resonance part 120A and a second parasitic resonance part 120B are provided between the second main resonance element 110B and the first main resonance element 110A.

[0054] The second main resonator 110B has an end edge 111B extending in the Y direction on the −X direction side. The second parasitic resonator 122 and the fourth parasitic resonator 124 are provided adjacent to the end edge 111B on the −X direction side, and the first parasitic resonator 121 and the third parasitic resonator 123 are provided adjacent to the second parasitic resonator 122 and the fourth parasitic resonator 124 on the −X direction side.

[0055] When the first switching element 125A and the second switching element 125B are both in a non-conductive state, the second parasitic resonator element 122 and the fourth parasitic resonator element 124 parasitize the second main resonator element 110B. When the first switching element 125A is in a conductive state and the second switching element 125B is in a non-conductive state, the first parasitic resonator element 121 and the second parasitic resonator element 122 parasitize the second main resonator element 110B, and the fourth parasitic resonator element 124 parasitizes the second main resonator element 110B.

[0056] When the first switching element 125A is in a non-conductive state and the second switching element 125B is in a conductive state, the second parasitic resonator element 122 is parasitic on the second main resonator element 110B, and the third parasitic resonator element 123 and the fourth parasitic resonator element 124 are also parasitic on the second main resonator element 110B. When the first switching element 125A and the second switching element 125B are both in a conductive state, the first parasitic resonator element 121 and the second parasitic resonator element 122 are parasitic on the second main resonator element 110B, and the third parasitic resonator element 123 and the fourth parasitic resonator element 124 are also parasitic on the second main resonator element 110B.

[0057] <First Parasitic Resonance Element 121> The first parasitic resonator element 121 is provided between the first main resonator element 110A and the second main resonator element 110B, on the first main resonator element 110A side. The first parasitic resonator element 121 is provided adjacent to the end edge 111A on the +X direction side and adjacent to the third parasitic resonator element 123 on the −Y direction side. The first parasitic resonator element 121 is located on the +Y direction side of a line connecting the end point of the end edge 111A of the first main resonator element 110A on the −Y direction side and the end point of the end edge 111B of the second main resonator element 110B on the −Y direction side, but a part of the first parasitic resonator element 121 may protrude from this line on the −Y direction side.

[0058] The first parasitic resonator element 121 is parasitic on the first main resonator element 110A, and when the first main resonator element 110A resonates, the first parasitic resonator element 121 becomes one with the first main resonator element 110A and resonates together with the first main resonator element 110A.

[0059] In addition, when one resonant element 1 is parasitic on another resonant element, it means that the presence of another resonant element around one resonant element 1 causes a non-negligible change in the resonant frequency of the one resonant element 1.

[0060] For example, the first parasitic resonator element 121 has an H-shape in plan view. For example, the length in the X direction of the first parasitic resonator element 121 is the same as the length in the X direction of the third parasitic resonator element 123, which also has an H-shape in plan view, and the positions of both ends in the X direction are aligned with those of the third parasitic resonator element 123. For example, the length in the Y direction of the first parasitic resonator element 121 is longer than the length in the Y direction of the third parasitic resonator element 123, which also has an H-shape in plan view. Therefore, for example, the first parasitic resonator element 121 is larger than the third parasitic resonator element 123 in plan view. In other words, the lengths of two of the three linear portions of the first parasitic resonator element 121 that are H-shaped in plan view and extend in the Y direction are longer than the lengths of two of the three linear portions of the third parasitic resonator element 123 that are H-shaped in plan view and extend in the Y direction. The resonant frequency of the first parasitic resonant element 121 will be described later together with the operation of the cell 100A.

[0061] A first switching element 125A is connected to one of the three linear portions of the first parasitic resonant element 121, which is H-shaped in plan view and extends in the Y direction on the +X direction side. The first switching element 125A is configured with a switching element such as a PIN diode, and is therefore capable of switching the connection state between the first parasitic resonant element 121 and the second parasitic resonant element 122.

[0062] When the first switching element 125A is on (conductive state), the first parasitic resonator element 121 is electrically connected to the second parasitic resonator element 122 and can resonate together with the second parasitic resonator element 122. On the other hand, when the first switching element 125A is off (non-conductive state), the first parasitic resonator element 121 is not electrically connected to the second parasitic resonator element 122 and does not resonate together with the second parasitic resonator element 122.

[0063] <Second Parasitic Resonance Element 122> The second parasitic resonator element 122 is provided between the first main resonator element 110A and the second main resonator element 110B, on the second main resonator element 110B side. The second parasitic resonator element 122 is provided adjacent to the −X direction side of the end edge 111B and adjacent to the −Y direction side of the fourth parasitic resonator element 124. The second parasitic resonator element 122 is located on the +Y direction side of a line connecting the −Y direction end point of the end edge 111A of the first main resonator element 110A and the −Y direction end point of the end edge 111B of the second main resonator element 110B, but a part of the second parasitic resonator element 122 may protrude from this line in the −Y direction.

[0064] The second parasitic resonator element 122 is parasitic on the second main resonator element 110B, and when the second main resonator element 110B resonates, the second parasitic resonator element 122 becomes one with the second main resonator element 110B and resonates together with the second main resonator element 110B.

[0065] For example, the second parasitic resonator element 122 has an H-shape in plan view. The size and shape of the second parasitic resonator element 122 in plan view are the same as those of the first parasitic resonator element 121, but may be different.

[0066] The length in the X direction of the second parasitic resonator element 122 is the same as the length in the X direction of the fourth parasitic resonator element 124, which is, for example, H-shaped in a plan view, and the positions of both ends in the X direction are aligned with those of the fourth parasitic resonator element 124. The length in the Y direction of the second parasitic resonator element 122 is, for example, longer than the length in the Y direction of the fourth parasitic resonator element 124, which is, for example, H-shaped in a plan view. Therefore, for example, the second parasitic resonator element 122 is larger than the fourth parasitic resonator element 124 in a plan view. In other words, the lengths of two of the three linear portions of the second parasitic resonator element 122, which is H-shaped in a plan view, that extend in the Y direction are longer than the lengths of two of the three linear portions of the fourth parasitic resonator element 124, which is H-shaped in a plan view. The resonant frequency of the second parasitic resonator element 122 will be described later along with the operation of the cell 100A.

[0067] Of the three linear portions of the second parasitic resonant element 122 that are H-shaped in plan view, one linear portion that extends in the Y direction on the −X direction side is connected to a first switching element 125A. Therefore, by switching the conduction state of the first switching element 125A, it is possible to switch the connection state between the second parasitic resonant element 122 and the first parasitic resonant element 121.

[0068] When the first switching element 125A is on, the second parasitic resonator element 122 is electrically connected to the first parasitic resonator element 121 and can resonate together with the first parasitic resonator element 121. On the other hand, when the first switching element 125A is off, the second parasitic resonator element 122 is not electrically connected to the first parasitic resonator element 121 and does not resonate together with the first parasitic resonator element 121.

[0069] <Third Parasitic Resonance Element 123> The third parasitic resonator element 123 is provided between the first main resonator element 110A and the second main resonator element 110B, on the first main resonator element 110A side. The third parasitic resonator element 123 is provided adjacent to the +X direction side of the end edge 111A and adjacent to the +Y direction side of the first parasitic resonator element 121. The third parasitic resonator element 123 is located on the -Y direction side of a line connecting the +Y direction end point of the end edge 111A of the first main resonator element 110A and the +Y direction end point of the end edge 111B of the second main resonator element 110B, but a part of the third parasitic resonator element 123 may protrude beyond this line in the +Y direction.

[0070] The third parasitic resonator element 123 is parasitic on the first main resonator element 110A, and when the first main resonator element 110A resonates, the third parasitic resonator element 123 becomes one with the first main resonator element 110A and resonates together with the first main resonator element 110A.

[0071] For example, the third parasitic resonator element 123 has an H-shape in plan view. For example, the length in the X direction of the third parasitic resonator element 123 is the same as the length in the X direction of the first parasitic resonator element 121, which has an H-shape in plan view, and the positions of both ends in the X direction are aligned with those of the first parasitic resonator element 121. For example, the length in the Y direction of the third parasitic resonator element 123 is shorter than the length in the Y direction of the first parasitic resonator element 121, which has an H-shape in plan view. Therefore, for example, the third parasitic resonator element 123 is smaller than the first parasitic resonator element 121 in plan view. In other words, the lengths of two of the three linear portions of the third parasitic resonator element 123 that are H-shaped in plan view and extend in the Y direction are shorter than the lengths of two of the three linear portions of the first parasitic resonator element 121 that are H-shaped in plan view and extend in the Y direction. The resonant frequency of the third parasitic resonant element 123 will be described later together with the operation of the cell 100A.

[0072] The second switching element 125B is connected to one of the three linear portions of the third parasitic resonator element 123, which is H-shaped in plan view and extends in the Y direction on the +X direction side. The second switching element 125B is configured with a switching element such as a PIN diode, and is therefore capable of switching the connection state between the third parasitic resonator element 123 and the fourth parasitic resonator element 124.

[0073] When the second switching element 125B is on, the third parasitic resonator element 123 is electrically connected to the fourth parasitic resonator element 124 and can resonate together with the fourth parasitic resonator element 124. On the other hand, when the second switching element 125B is off, the third parasitic resonator element 123 is not electrically connected to the fourth parasitic resonator element 124 and does not resonate together with the fourth parasitic resonator element 124.

[0074] <Fourth parasitic resonator element 124> The fourth parasitic resonator element 124 is provided between the first main resonator element 110A and the second main resonator element 110B, on the second main resonator element 110B side. The fourth parasitic resonator element 124 is provided adjacent to the −X direction side of the end edge 111B and adjacent to the +Y direction side of the second parasitic resonator element 122. The fourth parasitic resonator element 124 is located on the −Y direction side of a line connecting the end point of the end edge 111A of the first main resonator element 110A on the +Y direction side and the end point of the end edge 111B of the second main resonator element 110B on the +Y direction side, but a part of the fourth parasitic resonator element 124 may protrude beyond this line in the +Y direction.

[0075] The fourth parasitic resonator element 124 is parasitic on the second main resonator element 110B, and when the second main resonator element 110B resonates, the fourth parasitic resonator element 124 becomes one with the second main resonator element 110B and resonates together with the second main resonator element 110B.

[0076] For example, the fourth parasitic resonator element 124 has an H-shape in plan view. The size and shape of the fourth parasitic resonator element 124 in plan view are the same as those of the third parasitic resonator element 123, but may be different.

[0077] The length of the fourth parasitic resonator element 124 in the X direction is the same as the length of the second parasitic resonator element 122, which is, for example, H-shaped in plan view, and the positions of both ends in the X direction are aligned with those of the second parasitic resonator element 122. The length of the fourth parasitic resonator element 124 in the Y direction is shorter than the length of the second parasitic resonator element 122, which is, for example, H-shaped in plan view. Therefore, the fourth parasitic resonator element 124 is, for example, smaller than the second parasitic resonator element 122 in plan view. In other words, the lengths of two of the three linear portions of the fourth parasitic resonator element 124, which is H-shaped in plan view, that extend in the Y direction are shorter than the lengths of two of the three linear portions of the second parasitic resonator element 122, which is H-shaped in plan view. The resonant frequency of the fourth parasitic resonator element 124 will be described later along with the operation of the cell 100A.

[0078] The second switching element 125B is connected to one of the three linear portions of the fourth parasitic resonator element 124 that is H-shaped in plan view and extends in the Y direction on the −X direction side. Therefore, by switching the conduction state of the second switching element 125B, it is possible to switch the connection state between the fourth parasitic resonator element 124 and the third parasitic resonator element 123.

[0079] When the second switching element 125B is on, the fourth parasitic resonator element 124 is electrically connected to the third parasitic resonator element 123 and can resonate together with the third parasitic resonator element 123. On the other hand, when the second switching element 125B is off, the fourth parasitic resonator element 124 is not electrically connected to the third parasitic resonator element 123 and does not resonate together with the third parasitic resonator element 123.

[0080] In the above description, the first parasitic resonator 121 and the second parasitic resonator 122 are larger in size than the third parasitic resonator 123 and the fourth parasitic resonator 124. That is, the first parasitic resonator 120A is larger in size than the second parasitic resonator 120B. However, the first parasitic resonator 120A may be smaller in size than the second parasitic resonator 120B. By making the first parasitic resonator 120A and the second parasitic resonator 120B different in size, it becomes easier to adjust the phase differences of the three or more reflection phases to be closer to equal.

[0081] The first parasitic resonator 120A and the second parasitic resonator 120B may be equal in size. In this case, the first parasitic resonator element 121, the second parasitic resonator element 122, the third parasitic resonator element 123, and the fourth parasitic resonator element 124 may be equal in size. Alternatively, the first parasitic resonator element 121 and the third parasitic resonator element 123 may be equal in size, the second parasitic resonator element 122 and the fourth parasitic resonator element 124 may be equal in size, and the first parasitic resonator element 121 and the third parasitic resonator element 123 may be different in size from the second parasitic resonator element 122 and the fourth parasitic resonator element 124.

[0082] <First switching element 125A> The first switching element 125A is provided between the first parasitic resonant element 121 and the second parasitic resonant element 122. The first switching element 125A is an element having two terminals, one connected to the first parasitic resonant element 121 and the other connected to the second parasitic resonant element 122, and is capable of switching between a conductive state and a non-conductive state between the two terminals.

[0083] The first switching element 125A is configured, for example, by a PIN diode, a field effect transistor (FET), a transistor, a varactor, or a micro electro mechanical systems (MEMS) switch. These are elements that can be electrically switched on and off by supplying power from an external source. Here, as an example, a configuration in which the first switching element 125A is configured by a PIN diode will be described.

[0084] When the first switching element 125A is turned on, the first parasitic resonant element 121 and the second parasitic resonant element 122 are electrically connected to each other, and when the first switching element 125A is turned off, the first parasitic resonant element 121 and the second parasitic resonant element 122 are not electrically connected to each other.

[0085] One of the two terminals of the first switching element 125A may be connected to the ground (reference potential point) so that a control command output from the control unit 5 is input thereto, for example, via an RF choke or the like, and the other of the two terminals of the first switching element 125A may be connected to the ground (reference potential point). In this way, the first switching element 125A can be switched on and off by the control command output from the control unit 5.

[0086] <Second switching element 125B> The second switching element 125B is provided between the third parasitic resonator element 123 and the fourth parasitic resonator element 124. The second switching element 125B is an element having two terminals, one connected to the third parasitic resonator element 123 and the other connected to the fourth parasitic resonator element 124, and is capable of switching between a conductive state and a non-conductive state between the two terminals.

[0087] The second switching element 125B is configured, for example, by a PIN diode, an FET, a transistor, a varactor, or a MEMS switch, similar to the first switching element 125A. The second switching element 125B is preferably configured by the same switching element as the first switching element 125A. Here, as an example, a configuration in which the second switching element 125B is configured by a PIN diode will be described.

[0088] When the second switching element 125B is turned on, the third parasitic resonant element 123 and the fourth parasitic resonant element 124 are electrically connected to each other, and when the second switching element 125B is turned off, the third parasitic resonant element 123 and the fourth parasitic resonant element 124 are not electrically connected to each other.

[0089] Furthermore, when the first switching element 125A and the second switching element 125B are both turned on, an electrical connection is established between the first parasitic resonant element 121 and the second parasitic resonant element 122 and between the third parasitic resonant element 123 and the fourth parasitic resonant element 124.

[0090] One of the two terminals of the second switching element 125B may be connected to the ground (reference potential point) so that a control command output from the control unit 5 is input thereto, for example, via an RF choke or the like, and the other of the two terminals of the second switching element 125B may be connected to the ground (reference potential point). In this way, the second switching element 125B can be switched on and off by the control command output from the control unit 5.

[0091] <Resonant frequencies of each part of cell 100A and operation of cell 100A> Here, when explaining the resonant frequencies of each part of cell 100A, the first main resonant element 110A, the second main resonant element 110B, the first parasitic resonant element 121, the second parasitic resonant element 122, the third parasitic resonant element 123, and the fourth parasitic resonant element 124 included in cell 100A will simply be referred to as the six resonant elements of cell 100A.

[0092] It is known that when two resonant elements having substantially the same resonant frequency are placed close to each other, their reflection characteristics change due to interaction. Therefore, when the resonant frequencies of the first main resonant element 110A, the second main resonant element 110B, the first parasitic resonant element 121, the second parasitic resonant element 122, the third parasitic resonant element 123, and the fourth parasitic resonant element 124, the first parasitic resonant element 121 and the second parasitic resonant element 122 when the first switching element 125A is turned on, and the third parasitic resonant element 123 and the fourth parasitic resonant element 124 when the second switching element 125B is turned on are substantially the same, switching the first switching element 125A and / or the second switching element 125B on and off changes the overall shape (or length) of the six resonant elements of the cell 100A, thereby changing the reflection characteristics of the cell 100A.

[0093] Specifically, when radio waves are incident on the cell 100A, the cell 100A operates as follows depending on the on / off states of the first switching element 125A and the second switching element 125B.

[0094] When the first switching element 125A and the second switching element 125B are both on, the first parasitic resonant element 121 and the second parasitic resonant element 122 are conductive (electrically connected), and the third parasitic resonant element 123 and the fourth parasitic resonant element 124 are conductive (electrically connected) and reflect radio waves.

[0095] Furthermore, when the first switching element 125A is on and the second switching element 125B is off, the first parasitic resonant element 121 and the second parasitic resonant element 122 are conductive, and the third parasitic resonant element 123 and the fourth parasitic resonant element 124 are not conductive and reflect radio waves.

[0096] Furthermore, when the first switching element 125A is off and the second switching element 125B is on, the first parasitic resonant element 121 and the second parasitic resonant element 122 are not conductive, and the third parasitic resonant element 123 and the fourth parasitic resonant element 124 are conductive and reflect radio waves.

[0097] Furthermore, when the first switching element 125A and the second switching element 125B are both off, the first parasitic resonant element 121 and the second parasitic resonant element 122 are not conductive, and the third parasitic resonant element 123 and the fourth parasitic resonant element 124 are not conductive and reflect radio waves.

[0098] As described above, when the first switching element 125A or the second switching element 125B is switched on and off, the connection relationship of the six resonant elements of the cell 100A changes, which changes the resonant frequency of the cell 100A and the reflection characteristics of the cell 100A. Furthermore, the change in the connection relationship of the six resonant elements of the cell 100A changes the amount of phase change of the cell 100A, which changes the reflection characteristics of the cell 100A. By changing the reflection characteristics of the cell 100A, the reflection phase of the reflected wave reflected by the cell 100A can be adjusted to three or more values. Furthermore, by adjusting the reflection phase in each cell 100A to three or more values, the reflection phase of the entire reflect array 100 can be adjusted to three or more values.

[0099] <Simulation of Reflection Phase (Part 1)> Figure 5B is a diagram showing an example of the results of a simulation (part 1) of the reflection phase of the reflectarray 100. For the reflectarray 100, an electromagnetic field simulation was performed to calculate the reflection phase while changing the frequency of the incident wave. Figure 5B shows, in tabular form, the reflection phase of the reflectarray 100 when the frequency of the incident wave is 26 GHz, 27 GHz, 28 GHz, and 29 GHz. The reflection phase is the reflection phase of a reflected wave that is a combination of multiple reflected waves that are obtained by reflecting an incident wave from multiple cells included in the reflectarray 100.

[0100] In the simulation, the reflection phase was calculated for three states (1) to (3). In state (1), the first switching element 125A and the second switching element 125B are both on (conductive). In state (2), the first switching element 125A is on (conductive) and the second switching element 125B is off (non-conductive). In state (3), the first switching element 125A is off (non-conductive) and the second switching element 125B is on (conductive). Note that FIG. 5B shows the reflection phase in states (1) and (3) when the reflection phase in state (2) is set to 0 degrees (deg).

[0101] The reflection phase at 26 GHz was 94 degrees in state (1), 0 degrees in state (2), and 192 degrees in state (3), resulting in three reflection phase values. Also, the reflection phase at 27 GHz was 110 degrees in state (1), 0 degrees in state (2), and 224 degrees in state (3), resulting in three reflection phase values.

[0102] The reflection phase at 28 GHz was 121 degrees in state (1), 0 degrees in state (2), and 245 degrees in state (3), resulting in three reflection phase values.The reflection phase at 29 GHz was 159 degrees in state (1), 0 degrees in state (2), and 280 degrees in state (3), resulting in three reflection phase values.

[0103] As described above, the reflection phase of the reflectarray 100 when the incident wave frequency was 26 GHz, 27 GHz, 28 GHz, and 29 GHz was changed between states (1) to (3), resulting in three reflection phases. At all frequencies, the deviation of the three values ​​within 360 degrees was relatively small, and good results were obtained. Ideally, the three reflection phases would be spaced at 120-degree intervals, but it was also confirmed that it is possible to approach the ideal even more by adjusting the length of each part of the reflectarray 100, etc.

[0104] <Simulation of Reflection Phase (Part 2)> Figure 5C is a diagram showing an example of the results of a simulation (Part 2) of the reflection phase of the reflectarray 100. After obtaining the simulation results (Part 1), the lengths of each part of the reflectarray 100 were adjusted, and a similar simulation (Part 2) was performed by adding state (4) to states (1) to (3). State (4) is a state in which both the first switching element 125A and the second switching element 125B are off (non-conductive). Note that Figure 5C shows the reflection phases in states (1) to (3) when the reflection phase in state (4) is set to 0 degrees (deg).

[0105] In the electromagnetic field simulation (part 2), four values ​​of the reflection phase were obtained at 28 GHz among 26 GHz, 27 GHz, 28 GHz, and 29 GHz. Specifically, the four values ​​were 276 degrees in state (1), 58 degrees in state (2), 200 degrees in state (3), and 0 degree in state (4). Three values ​​of the reflection phase were obtained at 26 GHz, 27 GHz, and 29 GHz. More specifically, at 26 GHz, 27 GHz, and 29 GHz, the difference between the reflection phase obtained in state (3) and the reflection phase obtained in state (4) was less than 10 degrees.

[0106] It was confirmed that three or more values ​​of the reflection phase can be obtained even when the first parasitic resonant element 121, the second parasitic resonant element 122, the third parasitic resonant element 123, and the fourth parasitic resonant element 124 have the same size.

[0107] <Simulation Results of Reflection Characteristics of Comparative Reflectarray with Binary Control> FIG. 6A is a diagram showing an example of simulation results of reflection characteristics of a comparative reflectarray with binary control.

[0108] The comparative binary control reflectarray has a configuration in which the second parasitic resonator 120B is omitted from each cell. That is, the comparative binary control reflectarray has a configuration in which only the first parasitic resonator 120A is disposed between the first main resonator element 110A and the second main resonator element 110B. In the comparative binary control reflectarray, the first parasitic resonator 120A is disposed evenly in the Y direction between the first main resonator element 110A and the second main resonator element 110B.

[0109] Such a comparative binary control reflectarray is a reflectarray that cannot obtain three or more reflection phase values ​​and can adjust the reflection phase in two values. It is known that a reflectarray that can adjust the reflection phase in two values ​​produces a signal due to unwanted reflection that has the same intensity as the reflected wave obtained in the direction of the set reflection angle in the opposite direction across from the front direction with respect to the direction of the set reflection angle.

[0110] For this binary control reflectarray for comparison, we calculated the radar cross section (dBsm) of the reflected wave when an incident wave was incident from the +Z direction toward the -Z direction. The radar cross section (dBsm) of the reflected wave represents the strength of the reflected wave (reflection intensity).

[0111] In Figure 6A, the radar cross section (dBsm) of the reflected wave at a cross section parallel to the XZ plane passing through the center of the binary control comparative reflectarray was calculated under the condition that the binary control comparative reflectarray includes a total of 100 cells, 10 cells (10 columns) in the X direction and 10 cells (10 rows) in the Y direction. The direction (reflection angle) in which the comparative reflectarray reflects radio waves was set to -15 degrees. The -15 degree direction is the reflection direction of the desired signal. The 0 degree direction is the +Z direction (front direction), and the 270 degree direction is the +X direction.

[0112] To set the reflection angle in the −15 degree direction, for example, from the first column closest to the −X direction to the tenth column closest to the +X direction, all first switching elements 125A were set to off in the first column, all first switching elements 125A were set to off in the second column, and all first switching elements 125A were set to on in the third column. Furthermore, all first switching elements 125A were set to on in the fourth column, all first switching elements 125A were set to on in the fifth column, and all first switching elements 125A were set to off in the sixth column. Furthermore, all first switching elements 125A were set to off in the seventh column, all first switching elements 125A were set to on in the eighth column, all first switching elements 125A were set to on in the ninth column, and all first switching elements 125A were set to on in the tenth column.

[0113] As shown in Figure 6A, the highest reflection intensity was in the direction of the set reflection angle (-15 degrees), at 1.6 dBsm. In addition, an unwanted signal (unwanted reflection) with a reflection intensity of 1.2 dBsm was generated in the direction of 15 degrees opposite the set reflection angle (-15 degrees), across from the front direction (0 degrees). It was confirmed that in a reflectarray with adjustable reflection phase in two values, unwanted reflections with the same intensity were generated in the opposite direction across from the front direction relative to the set reflection angle.

[0114] 6B is a diagram showing an example of the simulation results of the reflection characteristics of the reflect array 100. The intensity distribution of the reflected wave when an incident wave traveling from the +Z direction to the −Z direction is made incident on the reflect array 100 was calculated.

[0115] 6B shows the intensity distribution of the reflected waves in a cross section parallel to the XZ plane passing through the centers of the surfaces of the 100 cells 100A, where the reflectarray 100 includes a total of 100 cells 100A, 10 in the X direction and 10 in the Y direction. The direction (reflection angle) in which the reflectarray 100 reflects radio waves was set to -15 degrees. The -15 degree direction is the reflection direction of the desired signal.

[0116] To set the reflection angle in the -15 degree direction, for example, from the first column closest to the -X direction to the tenth column closest to the +X direction, in the first column, all first parasitic resonators 120A are turned off and all second switching elements 125B are turned on, and in the second column, all first switching elements 125A are turned off and all second switching elements 125B are turned off. Also, as an example, in the third column, all first switching elements 125A are turned off and all second switching elements 125B are turned off, and in the fourth column, all first switching elements 125A are turned on and all second switching elements 125B are turned off. Also, as an example, in the fifth column, all first switching elements 125A are turned on and all second switching elements 125B are turned off, and in the sixth column, all first switching elements 125A are turned off and all second switching elements 125B are turned on. As another example, in the seventh column, all first switching elements 125A are set to off and all second switching elements 125B are set to on, in the eighth column, all first switching elements 125A are set to off and all second switching elements 125B are set to off, in the ninth column, all first switching elements 125A are set to on and all second switching elements 125B are set to off, and in the tenth column, all first switching elements 125A are set to on and all second switching elements 125B are set to off.

[0117] 6B, the highest reflection intensity was 3.4 dBsm in the direction of the reflection angle (-15 degrees) of the desired signal. In other words, the peak value of the radio wave intensity was 3.4 dBsm.

[0118] Furthermore, the direction with the highest reflection intensity outside the reflection angle was approximately 25 degrees, at -2.2 dBsm. The direction with the highest reflection intensity outside the reflection angle is the direction with the second highest reflection intensity. This second highest reflection intensity direction is an unwanted signal (unwanted reflection) that is output in an unintended direction different from the intended reflection angle.

[0119] The unwanted signal with the second highest reflection intensity was reduced by 5.6 dB compared to the peak value of the radio wave intensity, confirming that the intensity of the unwanted signal was sufficiently reduced. It was also confirmed that unwanted reflections with the same intensity in the opposite direction across from the front direction relative to the set reflection angle, such as those of the comparative reflectarray shown in Figure 6A, were suppressed. In this way, it was confirmed that the reflectarray 100 can reflect radio waves only in the direction of the set reflection angle.

[0120] As described above, the reflectarray 100 includes the first parasitic resonator 120A and the second parasitic resonator 120B provided between the first main resonator element 110A and the second main resonator element 110B, and the reflection phase can be adjusted to three or more values ​​by adjusting the resonant frequency of each cell 100A. As a result of various simulations, it was found that the peak value of the radio wave intensity is preferably 3 dB or more higher than the unwanted signal with the second highest reflection intensity. The peak value of the radio wave intensity that is 3 dB or more higher than the unwanted signal with the second highest reflection intensity is the only peak in the distribution of reflection intensity. In a reflectarray that controls the reflection phase using two values, such a single peak value of the radio wave intensity cannot be obtained, so three or more reflection phases are obtained, and the difference in intensity between the peak value of the radio wave intensity and the unwanted signal with the second highest reflection intensity is 3 dB or more.

[0121] <Effects> The reflect array 100 includes a plurality of cells 100A and is capable of setting the reflection angle of radio waves to an angle other than specular reflection, and each of the plurality of cells 100A includes a first main resonance element 110A, a second main resonance element 110B, a first parasitic resonance part 120A provided between the first main resonance element 110A and the second main resonance element 110B, and a second parasitic resonance part 120B provided between the first main resonance element 110A and the second main resonance element 110B, and the reflection phase of each of the plurality of cells 100A can be adjusted to three or more values ​​by adjusting the resonance frequency.

[0122] In this way, three or more values ​​of reflection phase can be obtained by using the first parasitic resonator 120A and the second parasitic resonator 120B provided between the two resonator elements (the first main resonator element 110A and the second main resonator element 110B). That is, three or more values ​​of reflection phase can be realized by a configuration in which two parasitic resonators are provided for two resonator elements.

[0123] Therefore, it is possible to provide a reflect array 100 that is simple in configuration and that can adjust the reflection phase to three or more values.

[0124] Furthermore, each of the plurality of cells 100A may be capable of adjusting the reflection phase to four or more values ​​by adjusting the resonance frequency, thereby providing a reflect array 100 that is capable of adjusting the reflection phase to four or more values ​​and has a simple configuration.

[0125] The first parasitic resonator 120A and the second parasitic resonator 120B may have different sizes. By making the sizes of the first parasitic resonator 120A and the second parasitic resonator 120B different, it becomes easier to adjust the phase differences of the three or more reflection phases to be more uniform.

[0126] The first parasitic resonance unit 120A includes a first parasitic resonance element 121 provided on the first main resonance element 110A side, a second parasitic resonance element 122 provided on the second main resonance element 110B side, and a first switching element 125A that can switch the connection state between the first parasitic resonance element 121 and the second parasitic resonance element 122. The second parasitic resonance unit 120B includes a third parasitic resonance element 123 provided on the first main resonance element 110A side, a fourth parasitic resonance element 124 provided on the second main resonance element 110B side, and a second switching element 125B that can switch the connection state between the third parasitic resonance element 123 and the fourth parasitic resonance element 124. The resonant frequency of the cell 100A may be adjustable by switching the connection states of the first switching element 125A and the second switching element 125B. The first parasitic resonator 120A and the second parasitic resonator 120B have a simple configuration in which each has two parasitic resonator elements and one switching element, and by switching the connection state of the two switching elements, a reflect array 100 can be provided in which the reflection phase can be more reliably adjusted to three or more values.

[0127] The first switching element 125A and the second switching element 125B may be a PIN diode, an FET, a transistor, a varactor, or a MEMS switch. Using these switching elements, the first switching element 125A and the second switching element 125B can easily and reliably switch between a connection state between the first parasitic resonant element 121 and the second parasitic resonant element 122 and a connection state between the third parasitic resonant element 123 and the fourth parasitic resonant element 124.

[0128] The reflect array 100 includes a plurality of cells 100A and is capable of setting the reflection angle of radio waves to an angle other than specular reflection, and each of the plurality of cells 100A includes a first main resonance element 110A, a second main resonance element 110B, and a parasitic resonance part provided between the first main resonance element 110A and the second main resonance element 110B, and the peak value of the radio wave intensity in the direction of the reflection angle is 3 dB or more greater than the radio wave intensity in directions other than the direction.

[0129] In this way, by using the parasitic resonator provided between the two resonator elements (the first main resonator element 110A and the second main resonator element 110B), the peak value of the radio wave intensity in the direction of the reflection angle is 3 dB or more higher than the radio wave intensity in directions other than the direction. In a reflectarray that controls the reflection phase with two values, a single peak value of the radio wave intensity cannot be obtained, so three or more reflection phases are obtained, and the difference in intensity between the peak value of the radio wave intensity and the unwanted signal with the second highest reflection intensity is 3 dB or more.

[0130] Therefore, it is possible to provide a reflect array 100 that has a simple configuration, in which the reflection phase can be adjusted to three or more values, and the difference in intensity between the peak value of the radio wave intensity and the unwanted signal with the second highest reflection intensity is 3 dB or more.

[0131] Furthermore, the radio waves may be radio waves in the millimeter wave band. It is possible to provide a reflectarray 100 that is simple in configuration and that is capable of adjusting the reflection phase of radio waves in the millimeter wave band to three or more values.

[0132] <Embodiment 2> Fig. 7A is a diagram showing an example of the details of the configuration of a cell 200A of embodiment 2. The reflect array of embodiment 2 includes a cell 200A instead of the cell 100A of embodiment 1. The cell 200A is provided on the surface of the substrate 101 on the +Z direction side, similar to the cell 100A of embodiment 1. Fig. 7A shows a portion of the entire substrate 101 corresponding to one cell 200A, similar to Fig. 5A.

[0133] The cell 200A shown in Fig. 7A is a cell for horizontally polarized waves. If the cell 200A shown in Fig. 7A is rotated 90 degrees clockwise or counterclockwise in a plan view, a cell 200A that reflects vertically polarized radio waves can be obtained.

[0134] The cell 200A has a first main resonance element 110A, a second main resonance element 110B, and a parasitic resonance unit 220. The parasitic resonance unit 220 has a first parasitic resonance element 221, a second parasitic resonance element 222, a third parasitic resonance element 223, a first switching element 225A, and a second switching element 225B. The first main resonance element 110A and the second main resonance element 110B are, for example, the same as the first main resonance element 110A and the second main resonance element 110B in the first embodiment.

[0135] The parasitic resonance unit 220 is provided between the first main resonance element 110A and the second main resonance element 110B. The first parasitic resonance element 221, the first switching element 225A, the second parasitic resonance element 222, the second switching element 225B, and the third parasitic resonance element 223 are arranged in series in this order between the first main resonance element 110A and the second main resonance element 110B from the first main resonance element 110A side to the second main resonance element 110B side.

[0136] The first main resonator 110A, the parasitic resonator portion 220, the first parasitic resonator 221, the second parasitic resonator 222, and the third parasitic resonator 223 are formed of a metal layer, which may be the same metal layer as the metal layer forming the first parasitic resonator 121, the second parasitic resonator 122, the third parasitic resonator 123, and the fourth parasitic resonator 124 in the first embodiment.

[0137] Additionally, as an example, a configuration will be described in which the first parasitic resonant element 221, the second parasitic resonant element 222, and the third parasitic resonant element 223 are all H-shaped in a planar view, but the planar shapes of these resonant elements do not have to be H-shaped. For example, the planar shapes of these resonant elements may be linear, elongated in the Y direction, or may have other shapes. Furthermore, the planar shape of at least one of these resonant elements may be different from the others. Note that "having the same planar shape" includes shapes that are similar but different in size. Details of the sizes of the first parasitic resonant element 221, the second parasitic resonant element 222, and the third parasitic resonant element 223 will be described later.

[0138] <First Parasitic Resonance Element 221> The first parasitic resonator 221 is provided between the first main resonator 110A and the second main resonator 110B, adjacent to the first main resonator 110A. The first parasitic resonator 221 is provided adjacent to the +X direction side of the end edge 111A. The first parasitic resonator 221 is located between two straight lines connecting both ends in the Y direction of the end edge 111A of the first main resonator 110A and both ends in the Y direction of the end edge 111B of the second main resonator 110B, but a part of the first parasitic resonator 221 may extend outside the two straight lines.

[0139] The first parasitic resonator element 221 is parasitic on the first main resonator element 110A, and when the first main resonator element 110A resonates, the first parasitic resonator element 221 becomes one with the first main resonator element 110A and resonates together with the first main resonator element 110A.

[0140] For example, the first parasitic resonator element 221 has an H-shape in plan view. The length in the X direction of the first parasitic resonator element 221 is longer than the lengths in the X direction of the second parasitic resonator element 222 and the third parasitic resonator element 223, which are also H-shaped in plan view. In other words, the length of one of the three linear portions of the first parasitic resonator element 221 that is H-shaped in plan view and extends in the X direction is longer than the length of one of the three linear portions of the second parasitic resonator element 222 and the third parasitic resonator element 223 that are H-shaped in plan view and extend in the X direction.

[0141] The length in the Y direction of the first parasitic resonator element 221 is longer than the lengths in the Y direction of the second parasitic resonator element 222 and the third parasitic resonator element 223, which are, for example, H-shaped in plan view, and both ends in the Y direction are located outward in the X direction from both ends in the Y direction of the second parasitic resonator element 222 and the third parasitic resonator element 223. Therefore, for example, the first parasitic resonator element 221 is larger than the second parasitic resonator element 222 and the third parasitic resonator element 223 in plan view. In other words, the lengths of two of the three linear portions of the first parasitic resonator element 221 that are H-shaped in plan view and extend in the Y direction are longer than the lengths of two of the three linear portions of the second parasitic resonator element 222 and the third parasitic resonator element 223 that are H-shaped in plan view. Therefore, the resonant frequency of the first parasitic resonator element 221 will be described later along with the operation of the cell 200A.

[0142] A first switching element 225A is connected to one of the three linear portions of the first parasitic resonant element 221, which is H-shaped in plan view and extends in the Y direction on the +X direction side. The first switching element 225A is configured with a switching element such as a PIN diode, and is therefore capable of switching the connection state between the first parasitic resonant element 221 and the second parasitic resonant element 222.

[0143] When the first switching element 225A is on, the first parasitic resonator element 221 is electrically connected to the second parasitic resonator element 222 and can resonate together with the second parasitic resonator element 222. On the other hand, when the first switching element 225A is off, the first parasitic resonator element 221 is not electrically connected to the second parasitic resonator element 222 and does not resonate together with the second parasitic resonator element 222.

[0144] <Second parasitic resonator element 222> The second parasitic resonator element 222 is provided between the first parasitic resonator element 221 and the third parasitic resonator element 223. The second parasitic resonator element 222 is located between two straight lines connecting both ends in the Y direction of the end side 111A of the first main resonator element 110A and both ends in the Y direction of the end side 111B of the second main resonator element 110B, but a part of the second parasitic resonator element 222 may extend outside the two straight lines.

[0145] For example, the second parasitic resonator element 222 has an H-shape in plan view. For example, the size and shape of the second parasitic resonator element 222 in plan view are the same as the size and shape of the third parasitic resonator element 223. For example, the length in the X direction of the second parasitic resonator element 222 is the same as the length in the X direction of the third parasitic resonator element 223, which has an H-shape in plan view. For example, the length in the Y direction of the second parasitic resonator element 222 is shorter than the length in the Y direction of the third parasitic resonator element 223, which has an H-shape in plan view, and the positions of both ends in the Y direction are aligned with those of the third parasitic resonator element 223.

[0146] For example, the size and shape of the second parasitic resonator element 222 in a plan view are the same as, but may be different from, the size and shape of the third parasitic resonator element 223. Since the size and shape of the second parasitic resonator element 222 and the third parasitic resonator element 223 in a plan view are the same as, for example, the resonant frequency of the second parasitic resonator element 222 is the same as the resonant frequency of the third parasitic resonator element 223.

[0147] A first switching element 225A is connected to one of the three linear portions of the second parasitic resonator element 222 that is H-shaped in plan view and extends in the Y direction on the −X direction side, and a second switching element 225B is connected to one of the three linear portions that extends in the Y direction on the +X direction side. Therefore, by switching the conduction states of the first switching element 225A and the second switching element 225B, it is possible to switch the connection states between the second parasitic resonator element 222 and the first parasitic resonator element 221 and the third parasitic resonator element 223.

[0148] When the first switching element 225A is on and the second switching element 225B is off, the second parasitic resonator element 222 is electrically connected to the first parasitic resonator element 221 and is able to resonate together with the first parasitic resonator element 221. At this time, the second parasitic resonator element 222 does not resonate together with the first parasitic resonator element 221.

[0149] Furthermore, when the first switching element 225A is off and the second switching element 225B is on, the second parasitic resonator element 222 is electrically connected to the third parasitic resonator element 223 and is able to resonate together with the third parasitic resonator element 223. At this time, the second parasitic resonator element 222 does not resonate together with the first parasitic resonator element 221.

[0150] Furthermore, when the first switching element 225A and the second switching element 225B are both on, the second parasitic resonant element 222 is conductive with the first parasitic resonant element 221 and the third parasitic resonant element 223, and is able to resonate together with the first parasitic resonant element 221 and the third parasitic resonant element 223.

[0151] On the other hand, when the first switching element 225A and the second switching element 225B are both off, the second parasitic resonant element 222 is not electrically connected to the first parasitic resonant element 221 and the third parasitic resonant element 223, and does not resonate together with the first parasitic resonant element 221 and the third parasitic resonant element 223.

[0152] <Third Parasitic Resonance Element 223> The third parasitic resonator element 223 is provided on the second main resonator element 110B side. The third parasitic resonator element 223 is provided adjacent to the end edge 111B on the −X direction side. The third parasitic resonator element 223 is located between two straight lines connecting both ends in the Y direction of the end edge 111A of the first main resonator element 110A and both ends in the Y direction of the end edge 111B of the second main resonator element 110B, but a part of the third parasitic resonator element 223 may extend outside the two straight lines.

[0153] The third parasitic resonator element 223 is parasitic on the second main resonator element 110B, and when the second main resonator element 110B resonates, the third parasitic resonator element 223 becomes one with the second main resonator element 110B and resonates together with the second main resonator element 110B.

[0154] For example, the third parasitic resonator element 223 has an H-shape in plan view. The size and shape of the third parasitic resonator element 223 in plan view are the same as those of the second parasitic resonator element 222, but may be different.

[0155] The second switching element 225B is connected to one of the three linear portions of the H-shaped third parasitic resonator element 223 that extends in the Y direction on the −X direction side. Therefore, by switching the conduction state of the second switching element 225B, it is possible to switch the connection state between the third parasitic resonator element 223 and the second parasitic resonator element 222.

[0156] When the second switching element 225B is on, the third parasitic resonator element 223 is electrically connected to the second parasitic resonator element 222 and can resonate together with the second parasitic resonator element 222. On the other hand, when the second switching element 225B is off, the third parasitic resonator element 223 is not electrically connected to the second parasitic resonator element 222 and does not resonate together with the second parasitic resonator element 222.

[0157] In the above description, the first parasitic resonator element 221 is larger in size than the second parasitic resonator element 222 and the third parasitic resonator element 223. However, the first parasitic resonator element 221 may be smaller in size than the second parasitic resonator element 222 and the third parasitic resonator element 223.

[0158] Furthermore, the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223 may all be equal or may all be different. The first parasitic resonator element 221 and the second parasitic resonator element 222 may be equal in size and may be larger or smaller than the third parasitic resonator element 223. The first parasitic resonator element 221 and the third parasitic resonator element 223 may be equal in size and may be larger or smaller than the second parasitic resonator element 222. Note that, by making the size of at least one of the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223 different from the others, it becomes easier to adjust the phase differences of the three or more reflection phases to be more uniform.

[0159] <First switching element 225A> The first switching element 225A is provided between the first parasitic resonant element 221 and the second parasitic resonant element 222. The first switching element 225A is an element having two terminals, one connected to the first parasitic resonant element 221 and the other connected to the second parasitic resonant element 222, and is capable of switching between a conductive state and a non-conductive state between the two terminals.

[0160] The first switching element 225A is configured, for example, by a PIN diode, an FET, a transistor, a varactor, or a MEMS switch, similar to the first switching element 125A in embodiment 1. These are elements that can be electrically switched on and off by supplying power from an external source. Here, as an example, a configuration in which the first switching element 225A is configured by a PIN diode will be described.

[0161] When the first switching element 225A is turned on, the first parasitic resonant element 221 and the second parasitic resonant element 222 are electrically connected to each other, and when the first switching element 225A is turned off, the first parasitic resonant element 221 and the second parasitic resonant element 222 are not electrically connected to each other.

[0162] The configuration in which a control command is input to one of the two terminals of the first switching element 225A and the configuration in which the other terminal is connected to ground (reference potential point) may be the same as that of the first switching element 125A in embodiment 1. The first switching element 225A can be switched on and off by the control command output from the control unit 5.

[0163] <Second switching element 225B> The second switching element 225B is provided between the second parasitic resonant element 222 and the third parasitic resonant element 223. The second switching element 225B is an element having two terminals, one connected to the second parasitic resonant element 222 and the other connected to the third parasitic resonant element 223, and is capable of switching between a conductive state and a non-conductive state between the two terminals.

[0164] The second switching element 225B is configured, for example, by a PIN diode, an FET, a transistor, a varactor, or a MEMS switch, similar to the first switching element 225A. The second switching element 225B is preferably configured by the same switching element as the first switching element 225A. Here, as an example, a configuration in which the second switching element 225B is configured by a PIN diode will be described.

[0165] When the second switching element 225B is turned on, the second parasitic resonant element 222 and the third parasitic resonant element 223 are electrically connected to each other, and when the second switching element 225B is turned off, the second parasitic resonant element 222 and the third parasitic resonant element 223 are not electrically connected to each other.

[0166] Furthermore, when the first switching element 225A and the second switching element 225B are both turned on, the first parasitic resonant element 221, the second parasitic resonant element 222, and the third parasitic resonant element 223 are electrically connected to each other.

[0167] The second switching element 225B may have the same configuration as the first switching element 225A, in which a control command is input to one of the two terminals and the other is connected to ground (reference potential point). The second switching element 225B can be switched on and off by a control command output from the control unit 5.

[0168] <Resonant frequencies of each part of cell 200A and operation of cell 200A> Here, when explaining the resonant frequencies of each part of cell 200A, the first main resonant element 110A, the second main resonant element 110B, the first parasitic resonant element 221, the second parasitic resonant element 222, and the third parasitic resonant element 223 included in cell 200A will simply be referred to as the five resonant elements of cell 200A.

[0169] It is known that when two resonant elements having approximately the same resonant frequency are placed close to each other, the reflection characteristics change due to interaction. Therefore, when the resonance frequencies of the first main resonance element 110A, the second main resonance element 110B, the first parasitic resonance element 221, the second parasitic resonance element 222, the third parasitic resonance element 223, the first parasitic resonance element 221 and the second parasitic resonance element 222 when the first switching element 225A is turned on, the second parasitic resonance element 222 and the third parasitic resonance element 223 when the second switching element 225B is turned on, and the first parasitic resonance element 221, the second parasitic resonance element 222, and the third parasitic resonance element 223 when both the first switching element 225A and the second switching element 225B are turned on are substantially the same, switching the first switching element 225A and / or the second switching element 225B on and off changes the overall shape (or length) of the five resonance elements of the cell 200A, and changes the reflection characteristics of the cell 200A.

[0170] Specifically, when radio waves are incident on the cell 200A, the cell 200A operates as follows depending on the on / off states of the first switching element 225A and the second switching element 225B.

[0171] When the first switching element 225A and the second switching element 225B are both on, the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223 are in a conductive state and reflect radio waves.

[0172] Furthermore, when the first switching element 225A is on and the second switching element 225B is off, the first parasitic resonant element 221 and the second parasitic resonant element 222 are conductive, and the second parasitic resonant element 222 and the third parasitic resonant element 223 are not conductive and reflect radio waves.

[0173] Furthermore, when the first switching element 225A is off and the second switching element 225B is on, the first parasitic resonant element 221 and the second parasitic resonant element 222 are not conductive, and the second parasitic resonant element 222 and the third parasitic resonant element 223 are conductive and reflect radio waves.

[0174] Furthermore, when the first switching element 225A and the second switching element 225B are both off, the first parasitic resonant element 221 and the second parasitic resonant element 222 are not conductive, and the second parasitic resonant element 222 and the third parasitic resonant element 223 are conductive and reflect radio waves.

[0175] As described above, when the first switching element 225A or the second switching element 225B is switched on and off, the connection relationship of the five resonant elements of the cell 200A changes, which changes the resonant frequency of the cell 200A and the reflection characteristics of the cell 200A. Furthermore, the connection relationship of the five resonant elements of the cell 200A changes, which changes the amount of phase change of the cell 200A and changes the reflection characteristics of the cell 200A. By changing the reflection characteristics of the cell 200A, the reflection phase of the reflected wave reflected by the cell 200A can be adjusted to three or more values. Furthermore, by adjusting the reflection phase of each cell 200A to three or more values, the reflection phase of the entire reflect array of embodiment 2 can be adjusted to three or more values.

[0176] <Simulation of Reflection Phase> Fig. 7B is a diagram showing an example of the results of a simulation of the reflection phase of the reflectarray of embodiment 2. For the reflectarray of embodiment 2, an electromagnetic field simulation was performed to calculate the reflection phase while changing the frequency of the incident wave. Fig. 7B shows, in tabular form, the reflection phase of the reflectarray of embodiment 2 when the incident wave frequency is 26 GHz, 26.5 GHz, 27 GHz, and 27.5 GHz. The reflection phase is the reflection phase of a reflected wave obtained by combining multiple reflected waves obtained by reflecting an incident wave from multiple cells included in the reflectarray of embodiment 2.

[0177] In the simulation, the reflection phase was calculated for four states (1) to (4). In state (1), the first switching element 225A and the second switching element 225B are both on. In state (2), the first switching element 225A is on and the second switching element 225B is off. In state (3), the first switching element 225A is off and the second switching element 225B is on. In state (4), the first switching element 225A and the second switching element 225B are both off. Note that FIG. 7B shows the reflection phase in states (2) to (4) when the reflection phase in state (1) is set to 0 degrees (deg).

[0178] The reflection phase at 26 GHz was 0 degrees in state (1), 176 degrees in state (2), 260 degrees in state (3), and 309 degrees in state (4), resulting in four reflection phase values. Also, the reflection phase at 26.5 GHz was 0 degrees in state (1), 133 degrees in state (2), 240 degrees in state (3), and 306 degrees in state (4), resulting in four reflection phase values.

[0179] The reflection phase at 27 GHz was 0 degrees in state (1), 100 degrees in state (2), 216 degrees in state (3), and 302 degrees in state (4), resulting in four reflection phase values.The reflection phase at 27.5 GHz was 0 degrees in state (1), 72 degrees in state (2), 188 degrees in state (3), and 298 degrees in state (4), resulting in four reflection phase values.

[0180] As described above, the reflection phase of the reflectarray of embodiment 2 when the incident wave frequency was 26 GHz, 26.5 GHz, 27 GHz, and 27.5 GHz was changed between states (1) to (4), resulting in four reflection phase values. At each frequency, the deviation of the four values ​​within 360 degrees was relatively small, and good results were obtained. Ideally, the four reflection phases would be spaced at 90-degree intervals, but it was also confirmed that it is possible to approach the ideal even more by adjusting the length of each part of the reflectarray of embodiment 2.

[0181] <Effects> The reflectarray of Embodiment 2 of Embodiment 2 includes a plurality of cells 200A and is capable of setting the reflection angle of radio waves to an angle other than that of specular reflection, and each of the plurality of cells 200A includes a first main resonance element 110A, a second main resonance element 110B, and a parasitic resonance part 220 provided between the first main resonance element 110A and the second main resonance element 110B, and the parasitic resonance part 220 has a first parasitic resonance element 221, a second parasitic resonance element 222, and a third parasitic resonance element 223 provided between the first main resonance element 110A and the second main resonance element 110B, and the reflection phase of each of the plurality of cells 200A can be adjusted to three or more values ​​by adjusting the resonance frequency.

[0182] In this way, the parasitic resonator 220 provided between the two resonator elements (the first main resonator element 110A and the second main resonator element 110B) has three parasitic resonator elements (the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223), so that three or more values ​​of reflection phase can be obtained. That is, a configuration in which one parasitic resonator having three parasitic resonator elements is provided for two resonator elements can realize three or more values ​​of reflection phase.

[0183] Therefore, it is possible to provide a reflectarray of embodiment 2 that is simple in configuration and that can adjust the reflection phase to three or more values.

[0184] In addition, the parasitic resonator 220 may further include a first switching element 225A capable of switching the connection state between the first parasitic resonator element 221 and the second parasitic resonator element 222, and a second switching element 225B capable of switching the connection state between the second parasitic resonator element 222 and the third parasitic resonator element 223, and each of the multiple cells 200A may be capable of adjusting the reflection phase to three or more values ​​by adjusting the resonant frequency by switching the connection state using the first switching element 225A and the second switching element 225B.

[0185] In this way, three or more values ​​of reflection phase can be obtained by a configuration in which the parasitic resonator 220 has two switching elements (the first switching element 225A and the second switching element 225B). That is, three or more values ​​of reflection phase can be realized by a configuration in which two switching elements are provided for two resonator elements.

[0186] Therefore, it is possible to provide a reflectarray of embodiment 2 that is simple in configuration and that can adjust the reflection phase to three or more values.

[0187] The first switching element 225A and the second switching element 225B may be a PIN diode, an FET, a transistor, a varactor, or a MEMS switch. Using these switching elements, the first switching element 225A and the second switching element 225B can easily and reliably switch the connection states of the first parasitic resonant element 221, the second parasitic resonant element 222, and the third parasitic resonant element 223.

[0188] Furthermore, each of the plurality of cells 200A may be capable of adjusting the reflection phase to four or more values ​​by adjusting the resonant frequency, so that it is possible to provide a reflectarray of embodiment 2 that is capable of adjusting the reflection phase to four or more values ​​and has a simple configuration.

[0189] At least two of the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223 may have different sizes. By having at least two of the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223 have different sizes, it becomes easier to adjust the phase differences of the three or more reflection phases to be more uniform.

[0190] Furthermore, the first parasitic resonator element 221, the second parasitic resonator element 222, and the third parasitic resonator element 223 may be arranged in series in this order between the first main resonator element 110A and the second main resonator element 110B. By arranging the three parasitic resonator elements in series, it becomes easier to design the resonant frequency of the cell 200A, and it also becomes easier to arrange a plurality of cells 200A.

[0191] Furthermore, the radio waves may be radio waves in the millimeter wave band. A reflectarray of embodiment 2 having a simple configuration and capable of adjusting the reflection phase of the millimeter wave band radio waves to three or more values ​​can be provided.

[0192] Reflectarrays according to exemplary embodiments of the present disclosure have been described above. However, the present disclosure is not limited to the specifically disclosed embodiments, and various modifications and changes are possible without departing from the scope of the claims.

[0193] This international application claims priority based on Japanese Patent Application No. 2023-190966, filed on November 8, 2023, the entire contents of which are incorporated herein by reference.

[0194] 100 Reflect array 100A Cell 110A First main resonance element 110B Second main resonance element 120A First parasitic resonance unit 121 First parasitic resonance element 122 Second parasitic resonance element 125A First switching element 120B Second parasitic resonance unit 123 Third parasitic resonance element 124 Fourth parasitic resonance element 125B Second switching element 200A Cell 220 Parasitic resonance unit 221 First parasitic resonance element 222 Second parasitic resonance element 223 Third parasitic resonance element 225A First switching element 225B Second switching element

Claims

1. A reflect array comprising multiple cells, capable of setting the radio wave reflection angle to an angle other than specular reflection, Each of the aforementioned plurality of cells is The first main resonant element, The second main resonant element, A first parasitic resonant portion is provided between the first main resonant element and the second main resonant element, A second parasitic resonant portion is provided between the first main resonant element and the second main resonant element. Includes, Each of the aforementioned cells is a reflect array in which the reflection phase can be adjusted to three or more values ​​by adjusting the resonant frequency.

2. The reflect array according to claim 1, wherein each of the plurality of cells is capable of adjusting the resonant frequency to adjust the reflection phase to four or more values.

3. The reflect array according to claim 1, wherein the first parasitic resonant portion and the second parasitic resonant portion are of different sizes.

4. The first parasitic resonance part is, A first parasitic resonant element provided on the side of the first main resonant element, A second parasitic resonant element provided on the side of the second main resonant element, A first switching element capable of switching the connection state between the first parasitic resonant element and the second parasitic resonant element, It has, The second parasitic resonance part is, A third parasitic resonant element provided on the side of the first main resonant element, A fourth parasitic resonant element provided on the side of the second main resonant element, A second switching element capable of switching the connection state between the third parasitic resonant element and the fourth parasitic resonant element, It has, The reflect array according to claim 1, wherein the first switching element and the second switching element can adjust the resonant frequency of the cell by switching the connection state.

5. The reflect array according to claim 4, wherein the first switching element and the second switching element are a PIN diode, an FET, a transistor, a varactor, or a MEMS switch.

6. A reflect array comprising multiple cells, capable of setting the radio wave reflection angle to an angle other than specular reflection, Each of the aforementioned plurality of cells is The first main resonant element, The second main resonant element, A parasitic resonant portion provided between the first main resonant element and the second main resonant element Includes, The parasitic resonant section includes a first parasitic resonant element, a second parasitic resonant element, and a third parasitic resonant element provided between the first main resonant element and the second main resonant element. Each of the aforementioned cells is a reflect array in which the reflection phase can be adjusted to three or more values ​​by adjusting the resonant frequency.

7. The aforementioned parasitic resonance part is A first switching element capable of switching the connection state between the first parasitic resonant element and the second parasitic resonant element, A second switching element capable of switching the connection state between the second parasitic resonant element and the third parasitic resonant element, It further possesses, The reflect array according to claim 6, wherein each of the plurality of cells can have its reflection phase adjusted to three or more values ​​by the first switching element and the second switching element switching the connection state to adjust the resonant frequency.

8. The reflect array according to claim 7, wherein the first switching element and the second switching element are a PIN diode, an FET, a transistor, a varactor, or a MEMS switch.

9. The reflect array according to claim 6, wherein each of the plurality of cells is capable of adjusting the resonant frequency to adjust the reflection phase to four or more values.

10. The reflect array according to claim 6, wherein at least two of the first parasitic resonant element, the second parasitic resonant element, and the third parasitic resonant element are of different sizes.

11. The reflect array according to claim 6, wherein the first parasitic resonant element, the second parasitic resonant element, and the third parasitic resonant element are provided in series in this order between the first main resonant element and the second main resonant element.

12. A reflect array comprising multiple cells, capable of setting the radio wave reflection angle to an angle other than specular reflection, Each of the aforementioned plurality of cells is The first main resonant element, The second main resonant element, A parasitic resonant portion provided between the first main resonant element and the second main resonant element Includes, A reflect array in which the peak value of the intensity of the radio waves in the direction of the aforementioned reflection angle is 3 dB or more greater than the intensity of the radio waves in directions other than the aforementioned direction.

13. The reflect array according to any one of claims 1 to 12, wherein the radio waves are in the millimeter wave band.