Planar antenna

Abstract

The present invention provides a planar antenna capable of radiating and receiving radio waves in opposite directions without requiring any change in orientation. [Solution] The planar antenna comprises a ground conductor layer, a dielectric layer including a first layer and a second layer disposed outside the ground conductor layer via the ground conductor layer, a first antenna conductor layer disposed on the first surface of the first layer opposite to the ground conductor layer and having a first radiating surface, and a second antenna conductor layer disposed on the second surface of the second layer opposite to the ground conductor layer and having a second radiating surface facing away from the first radiating surface.

Description

[Technical Field]

[0001] This invention relates to a planar antenna. [Background technology]

[0002] For example, Non-Patent Document 1 discloses a helical antenna that can handle two frequencies by incorporating the concept of an adaptive structure that changes the overall length by employing a lattice structure in the radiator that is expandable and retractable and has three structural safety points. As an ultralight planar patch antenna, an array antenna is known in which a patch pattern is directly printed on a retractable Kapton film (see, for example, Non-Patent Document 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] AIAA SciTech Forum January 3-7, 2022, San Diego, CA & Virtual AIAA SCITECH 2022 Forum, 10.2514 / 6.2022-0923, Enhancing multi-stability in helical lattices for adaptive structures, Maria Sakovsky, Rosette Maria Bichara, Youssef Tawk and Joseph Costantine [Non-Patent Document 2] AIAA SciTech Forum 8-12 January 2024, Orlando, FL. AIAA SCITECH 2024 Forum, Space Demonstration of Two-layer Deployable Membrane Reflectarray Antenna with Popup Book Mechanism, Hiraku Sakamoto, Takashi Tomura, Atsuki Ochi, Kazuki Nagai, Motoki Moritani, Gen Nakayama, and Taichi Oshino [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, planar antennas require a technology that allows them to radiate and receive radio waves in opposite directions without requiring a change in orientation. However, neither Non-Patent Documents 1 nor 2 discloses the above technology.

[0005] Therefore, the present invention aims to provide a planar antenna that can radiate and receive radio waves in opposite directions without requiring a change in orientation. [Means for solving the problem]

[0006] A planar antenna according to one aspect of the present invention comprises: a ground conductor layer; a dielectric layer including a first layer and a second layer disposed outside the ground conductor layer via the ground conductor layer; a first antenna conductor layer disposed on the first surface of the first layer opposite to the ground conductor layer and having a first radiating surface; and a second antenna conductor layer disposed on the second surface of the second layer opposite to the ground conductor layer and having a second radiating surface facing away from the first radiating surface. [Effects of the Invention]

[0007] According to the above aspect, it is possible to provide a planar antenna that can radiate and receive radio waves in opposite directions without requiring a change in posture.

Brief Description of the Drawings

[0008] [Figure 1] Perspective view of the planar antenna according to the first embodiment. [Figure 2] Plan view of the planar antenna according to the first embodiment as viewed from the first radiation surface side. [Figure 3] Plan view of the planar antenna according to the first embodiment as viewed from the second radiation surface side. [Figure 4] View including the IV-IV cross section of FIG. 2. [Figure 5] View showing the relationship between the frequency and gain (antenna gain) of the planar antenna according to the first embodiment. [Figure 6] View showing an example of dimensions including a plan view of the planar antenna according to the first embodiment as viewed from the first radiation surface side and two side views. [Figure 7] View showing an example of dimensions including a plan view of the planar antenna according to the first embodiment as viewed from the second radiation surface side. [Figure 8] View showing an example of dimensions including a plan view of the branch circuit section according to the first embodiment. [Figure 9] Plan view of the planar antenna according to the second embodiment as viewed from the first radiation surface side. [Figure 10] Plan view of the planar antenna according to the second embodiment as viewed from the second radiation surface side. [Figure 11] Perspective view of the planar antenna of the example. [Figure 12] Side view showing the radiation pattern of the planar antenna of the example at frequency ff. [Figure 13] Side view showing the radiation pattern of the planar antenna of the example at frequency fb. [Figure 14] View showing the analysis result of the relationship between the frequency and gain of the planar antenna of the example.

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the embodiments, as an example of a planar antenna, an example of a deployable two-panel patch antenna for space with switchable observation directions using different resonance frequencies will be described. For example, the planar antenna of the present embodiment is used for realizing a space solar power generation system (SSPS: Space Solar Power Systems), wireless energy transmission technology using microwaves or laser light, structural technology of large structures in space, and the like.

[0010] In the following description, expressions indicating relative or absolute arrangements such as "parallel", "orthogonal", "center", "coaxial", etc. not only strictly mean such arrangements and states, but also include arrangements and states that are relatively displaced with tolerances and angles or distances that can obtain the same function. In the drawings used in the following description, the scale of each member may be appropriately changed to show each member in a recognizable size.

[0011] <Planar Antenna> FIG. 1 is a perspective view of a planar antenna 1 according to the first embodiment. FIG. 2 is a plan view of the planar antenna 1 according to the first embodiment as viewed from the first radiation surface 4a side. FIG. 3 is a plan view of the planar antenna 1 according to the first embodiment as viewed from the second radiation surface 5a side. FIG. 4 is a view including the IV-IV cross section of FIG. 2. Referring to FIGS. 1 to 4 together, the planar antenna 1 includes a dielectric layer 2, a ground conductor layer 3, a first antenna conductor layer 4, and a second antenna conductor layer 5. For example, the planar antenna 1 is configured such that its shape is fixed when no heat or external force is acting, and it can recover to the stored initial shape when heat or external force acts.

[0012] In the following explanation, the x, y, and z Cartesian coordinate system will be used as needed. The x-direction corresponds to the left-right direction (width direction) of the planar antenna 1. The y-direction corresponds to the up-down direction (height direction) of the planar antenna 1. The z-direction corresponds to the front-to-back direction (thickness direction) of the planar antenna 1, which is perpendicular to both the x and y directions. In the following explanation, the direction indicated by the arrow in the diagram will be considered the positive (+) side, and the direction opposite to the arrow will be considered the negative (-) side. The +z side corresponds to the front side (first radiating surface 4a side), and the -z side corresponds to the rear side (second radiating surface 5a side).

[0013] In the example shown in the figure, the planar antenna 1 has a rectangular shape in plan view (a rectangle that is long in the x-direction). For example, the planar antenna 1 is formed as a rectangular plate in plan view. Note that the planar shape of the planar antenna 1 is not limited to the above and can be changed according to the design specifications.

[0014] For example, the thickness of the planar antenna 1 is between 1 mm and 10 mm. In the example shown in the figure, the thickness of the planar antenna 1 is approximately 6.4 mm. The thickness of the planar antenna 1 corresponds to the sum of the thickness of the dielectric layer 2, the ground conductor layer 3, the first antenna conductor layer 4, and the second antenna conductor layer 5. Note that the thickness of the planar antenna 1 is not limited to the above and can be changed according to the design specifications.

[0015] For example, the planar antenna 1 may be flexible as a whole. For example, the planar antenna 1 may be configured to bend like the side of a cylinder as a whole. For example, the planar antenna 1 may be configured to have flexible elastic properties that allow it to be folded.

[0016] <Dielectric layer> The dielectric layer 2 is a layered substrate mainly composed of dielectric material. The dielectric layer 2 plays a role in maintaining a constant distance between the ground conductor layer 3 and the first antenna conductor layer 4, and between the ground conductor layer 3 and the second antenna conductor layer 5. The dielectric layer 2 includes a first layer 21 and a second layer 22, which are arranged outside the ground conductor layer 3 via the ground conductor layer 3. The first layer 21 has a first surface 21a opposite to the ground conductor layer 3 in the z direction. The second layer 22 has a second surface 22a opposite to the ground conductor layer 3 in the z direction. The first surface 21a corresponds to one side of the first layer 21 in the thickness direction (the front surface of the dielectric layer 2) that constitutes the dielectric layer 2. The second surface 22a corresponds to the other side of the second layer 22 in the thickness direction (the rear surface of the dielectric layer 2) that constitutes the dielectric layer 2. The first surface 21a and the second surface 22a are parallel to each other.

[0017] The dielectric layer 2 is composed primarily of a shape memory polymer (SMP). The main component refers to a component that accounts for 50 wt% or more of the total material mass. For example, the dielectric layer 2 is preferably formed containing 80 wt% or more of the shape memory polymer, and more preferably containing 90 wt% or more. The proportion of the shape memory polymer in the dielectric layer 2 is not limited to the above and can be changed according to the design specifications.

[0018] Shape memory polymers have the following characteristics (1) to (5): (1) Store the shape formed at a temperature above the melting point. (2) After fabrication, the material will soften when heated above the glass transition temperature (Tg). (3) The softened molded object can be deformed and adjusted in shape. (4) When cooled in a deformed state, the shape becomes fixed. (5) When heated again, it softens and returns to its original shape that it has memorized.

[0019] For example, polyurethane-based shape memory polymers can be used as shape memory polymers. For instance, the dielectric layer 2 is formed from a polyurethane-based shape memory polymer. However, the material used to form the dielectric layer 2 is not limited to the above and can be changed according to the design specifications.

[0020] In the example shown in the figure, the dielectric layer 2 is rectangular (long in the x-direction) in a plan view. For example, each of the first layer 21 and the second layer 22 constituting the dielectric layer 2 is formed as a rectangular sheet in a plan view. In a plan view, the first layer 21 and the second layer 22 are rectangles of the same size.

[0021] For example, the thickness of the first layer 21 is between 1 mm and 5 mm. In the example shown in the figure, the thickness of the first layer 21 is approximately 3 mm. For example, the thickness of the second layer 22 is between 1 mm and 5 mm. In the example shown in the figure, the thickness of the second layer 22 is approximately 3 mm. For example, the thicknesses of the first layer 21 and the second layer 22 may be the same. Note that the thicknesses of the first layer 21 and the second layer 22 are not limited to those described above and can be changed according to the design specifications as long as the planar antenna 1 can function as an antenna.

[0022] For example, the first layer 21 and the second layer 22 may be formed using a shape memory polymer filament with a 3D printer. Alternatively, the first layer 21 and the second layer 22 may be formed using shape memory polymer powder with laser sintering. The method for forming the first layer 21 and the second layer 22 is not limited to the above and can be changed according to the design specifications.

[0023] <Ground Conductor Layer> The ground conductor layer 3 is positioned between the first layer 21 and the second layer 22. The ground conductor layer 3 is positioned opposite the first antenna conductor layer 4 via the first layer 21. The ground conductor layer 3 is positioned opposite the second antenna conductor layer 5 via the second layer 22. The ground conductor layer 3 functions as ground (GND) when the first antenna conductor layer 4 and / or the second antenna conductor layer 5 are operating. In plan view, the ground conductor layer 3 is rectangular in shape and the same size as the first layer 21.

[0024] For example, the ground conductor layer 3 is formed from a metal such as copper (an example of a conductor). However, the ground conductor layer 3 is not limited to the above and may be formed from gold, silver, aluminum, platinum, chromium, etc. For example, the material used to form the ground conductor layer 3 can be changed according to the design specifications.

[0025] For example, the thickness of the ground conductor layer 3 is between 0.01 mm and 0.05 mm. In the example shown in the figure, the thickness of the ground conductor layer 3 is approximately 0.03 mm. Note that the thickness of the ground conductor layer 3 is not limited to the above and can be changed according to the design specifications, as long as the planar antenna 1 can function as an antenna.

[0026] For example, the ground conductor layer 3 is formed by attaching a copper foil film to the surface of the first layer 21 opposite to the first surface 21a (the -Z side surface). For example, the ground conductor layer 3 may be formed on the surface of the first layer 21 opposite to the first surface 21a by methods such as plating or printing. For example, the first layer 21 and the second layer 22 may be bonded together, sharing the ground conductor layer 3. For example, it is desirable that the ground conductor layer 3 be formed by vapor deposition. Note that the method of forming the ground conductor layer 3 is not limited to the above and can be changed according to the design specifications.

[0027] <First antenna conductor layer> The first antenna conductor layer 4 has the role of converting radio waves irradiated from the outside into electric current, or converting a supplied electric current into radio waves to be radiated to the outside. The first antenna conductor layer 4 is arranged on the first surface 21a of the dielectric layer 2 (first layer 21). The first antenna conductor layer 4 has a first radiating surface 4a that radiates radio waves.

[0028] For example, the first antenna conductor layer 4 is formed of a metal such as copper (an example of a conductor). However, the first antenna conductor layer 4 is not limited to the above and may be formed of gold, silver, aluminum, platinum, chromium, etc. For example, the material used to form the first antenna conductor layer 4 can be changed according to the design specifications.

[0029] The thickness of the first antenna conductor layer 4 is between 0.01 mm and 0.3 mm. In the example shown in the figure, the thickness of the first antenna conductor layer 4 is approximately 0.05 mm. Note that the thickness of the first antenna conductor layer 4 is not limited to the above and can be changed according to the design specifications, as long as the planar antenna 1 can function as an antenna.

[0030] For example, the first antenna conductor layer 4 is formed on the first surface 21a of the first layer 21 by methods such as vapor deposition, plating, or printing. Note that the method of forming the first antenna conductor layer 4 is not limited to the above and can be changed according to the design specifications.

[0031] <Second antenna conductor layer> The second antenna conductor layer 5 has the role of converting radio waves irradiated from the outside into electric current, or converting a supplied electric current into radio waves to be radiated to the outside. The second antenna conductor layer 5 is located on the second surface 22a of the dielectric layer 2 (second layer 22). The second antenna conductor layer 5 has a second radiating surface 5a that radiates radio waves. The second radiating surface 5a faces away from the first radiating surface 4a.

[0032] For example, the second antenna conductor layer 5 is formed of a metal such as copper (an example of a conductor). However, the second antenna conductor layer 5 is not limited to the above and may be formed of gold, silver, aluminum, platinum, chromium, etc. For example, the second antenna conductor layer 5 may be formed of the same metal as the first antenna conductor layer 4. For example, the material used to form the second antenna conductor layer 5 can be changed according to the design specifications.

[0033] The thickness of the second antenna conductor layer 5 is between 0.01 mm and 0.3 mm. In the example shown in the figure, the thickness of the second antenna conductor layer 5 is approximately 0.05 mm. For example, the thickness of the second antenna conductor layer 5 may be the same as the thickness of the first antenna conductor layer 4. The thickness of the first antenna conductor layer 4 is not limited to the above and can be changed according to the design specifications, as long as the planar antenna 1 can function as an antenna.

[0034] For example, the second antenna conductor layer 5 is formed on the second surface 22a of the second layer 22 by methods such as vapor deposition, plating, or printing. Note that the method of forming the second antenna conductor layer 5 is not limited to the above and can be changed according to the design specifications.

[0035] <Relationship between frequency and gain (antenna gain) of a planar antenna> Figure 5 shows the relationship between frequency and gain (antenna gain) of the planar antenna 1 according to the first embodiment. In Figure 5, frequency f f This is the resonant frequency (Front active) when the gain on the first radiating surface 4a side (front side) of the planar antenna 1 is maximum, frequency f. b These values ​​represent the resonant frequencies (back active) at which the gain on the second radiating surface 5a side (rear side) of the planar antenna 1 is maximized. The first radiating surface 4a and the second radiating surface 5a can have their respective radiation patterns switched by changing the frequency. The first antenna conductor layer 4 and the second antenna conductor layer 5 have different resonant frequencies.

[0036] <Power supply section> Referring to Figures 1 to 4, the first antenna conductor layer 4 and the second antenna conductor layer 5 are connected to a common feed point 6. Although not shown, one end of a feed line (corresponding to the feed point) for supplying power to the first antenna conductor layer 4 and the second antenna conductor layer 5 is connected to the feed point 6. The other end of the feed line is connected to an external device (not shown). For example, a signal for switching the operating frequency may be sent from the external device to the feed point 6.

[0037] <Branching circuit section> The planar antenna 1 further comprises a branching circuit section 7 that distributes the current from the feed section 6. The branching circuit section 7 has a common section, a first end branching off from the common section to one side, and a second end branching off from the common section to the other side. The common section corresponds to the part of the branching circuit section 7 that is connected to the feed section 6. The branching circuit section 7 is formed in a T-shape in plan view. In plan view, the branching circuit section 7 is formed in a shape that extends from the center in the x-direction of the +y edge of the first surface 21a of the first layer 21 toward the -y side, and then branches out and extends to both sides in the x-direction. In the branching circuit section 7, the width in the y-direction gradually increases as you move from the center in the x-direction toward the outside in the x-direction.

[0038] <Configuration of the first antenna conductor layer> The first antenna conductor layer 4 includes a first patch section 40 and a first transmission line section 41 that connects the first end of the branch circuit section 7 to the first patch section 40.

[0039] In the example shown in the figure, due to the presence of the first transmission line section 41, the first patch section 40 is positioned offset to the -y side from the center of the first surface 21a in a plan view. Note that the arrangement of the first patch section 40 is not limited to the above and can be changed according to the design specifications. In a plan view, the first patch section 40 is smaller in size than the first layer 21.

[0040] In a plan view, the first transmission line section 41 is positioned on the +y side and -x side of the center of the first surface 21a. In a plan view, the first transmission line section 41 extends from the first end on the -x side of the branch circuit section 7 toward the -x side, then curves toward the -x side toward the -y side, then extends toward the center in the x direction toward the +x side, and then extends to the +y end side of the first patch section 40. In a plan view, the first transmission line section 41 extends with a uniform width from the first end on the -x side of the branch circuit section 7 toward the +y end side of the first patch section 40.

[0041] <Configuration of the second antenna conductor layer> The second antenna conductor layer 5 includes a second patch section 50 and a second transmission line section 51 that connects the second patch section 50 to a second end different from the first end of the branch circuit section 7.

[0042] In the example shown in the figure, due to the presence of the second transmission line section 51, the second patch section 50 is positioned offset to the -y side from the center of the second surface 22a in a plan view. Note that the arrangement of the second patch section 50 is not limited to the above and can be changed according to the design specifications. In a plan view, the second patch section 50 is rectangular in shape and smaller than the second layer 22.

[0043] In a plan view, the second transmission line section 51 is positioned on the +y side and +x side of the center of the second surface 22a. In a plan view, the second transmission line section 51 extends from the second end on the +x side of the branch circuit section 7 toward the +x side, then curves toward the +x side toward the -y side, then extends toward the center in the x direction toward the -x side, and then extends to the +y end side of the second patch section 50. In a plan view, the second transmission line section 51 extends with a uniform width from the second end on the +x side of the branch circuit section 7 toward the +y end side of the second patch section 50.

[0044] <Notch> A notch 42 for shifting the resonant frequency is formed in at least one of the first patch section 40 and the second patch section 50. The notch 42 is formed in the first patch section 40. In the example shown in the figure, the notch 42 is formed on both sides in the x-direction of the portion of the first patch section 40 to which the first transmission line section 41 is connected. No notch for shifting the resonant frequency is formed in the second patch section 50. Note that the manner in which the notch for shifting the resonant frequency is formed is not limited to the above and can be changed according to the design specifications.

[0045] <Through hole> A through-hole 8 is formed in the planar antenna 1, through which a portion of the branching circuit section 7 passes. In a plan view, the through-hole 8 is positioned on the +y side and shifted to the +x side from the center of the planar antenna 1. The through-hole 8 is formed to penetrate the first layer 21, the ground conductor layer 3, and the second layer 22. In a plan view, the through-hole 8 is rectangular in shape. In a plan view, the inner edge of the through-hole 8 is spaced apart from the outer edge of the branching circuit section 7.

[0046] <Example of a planar antenna design> Figure 6 is a diagram showing an example of dimensions, including a plan view and two side views of the planar antenna 1 according to the first embodiment, as seen from the first radiating surface 4a side. Figure 7 is a diagram showing an example of dimensions, including a plan view of the planar antenna 1 according to the first embodiment, as seen from the second radiating surface 5a side. Figure 8 is a diagram showing an example of dimensions, including a plan view of the branching circuit section 7 according to the first embodiment. The following describes a design example of the planar antenna 1 according to the first embodiment. In Figures 6 to 8 and the following equations, A: calculation variable, B: calculation variable, d: patch cutout length (corresponding to the y-direction dimension of the patch cutout 42), e: T-branch cutout length (corresponding to the y-direction dimension of the cutout in the branch circuit section 7), g: patch cutout width (corresponding to the x-direction dimension of the patch cutout 42), W: normal microstrip line width (corresponding to the width dimension perpendicular to the direction in which the transmission line extends in a plan view), W': microstrip line width immediately after the T-branch (corresponding to the y-direction dimension on the x-center side of the part that branches and extends on both sides in the x-direction in a plan view of the branch circuit section 7), W p : Width of the patch (corresponding to the x-direction dimension of patch section 40, 50), L: Width of the conductive hole (corresponding to the x-direction dimension of through hole 8), L p : Vertical width of the patch (corresponding to the y-direction dimension of patch sections 40 and 50), ΔL: Variable used for calculation, ε reff : Effective permittivity, ε r : Indicates the relative permittivity of dielectric layer 2, and t: Indicates the thickness of dielectric layer 2 (corresponding to the z-direction dimension of the first layer 21 and the second layer 22, respectively).

[0047] First, we find the variables A and B necessary for the calculation from the following equations (1) and (2).

[0048]

number

[0049] Next, calculate equations (3) and (4) below, select the appropriate equation from the W / t value, and determine the microstrip line width W.

[0050]

number

[0051] In a two-sided patch antenna, when splitting a single power supply to the front and back surfaces, it is preferable to ensure that the microstrip lines, including the original line, are not affected by reflections from the other two directions when splitting the lines in three directions. One way to achieve this is through a branching circuit called a T-junction, which distributes power by adjusting the line width (see Figure 8).

[0052] Total power P all Therefore, the power supplied to the left and right sides of the T-branch circuit can be expressed by the following equation (5) using the distribution coefficient K.

[0053]

number

[0054] When distributing power, the impedances Z1 and Z2, which correspond to the line widths W1 and W2 immediately after the branch, are calculated using the following equation (6).

[0055]

number

[0056] When the power is distributed evenly, K=0.5, and the result is expressed by the following equation (7).

[0057]

number

[0058] In a two-sided patch antenna, the following equation (8) is obtained by substituting the antenna design values ​​into equations (1) and (3) to determine the microstrip line width.

[0059]

number

[0060] Next, by substituting into equations (2) and (4) and performing the calculations, the following equation (9) is obtained.

[0061]

Equation

[0062] From this result, equation (9) is adopted to obtain W. Similarly, for the width W’ immediately after the T-branch, equations (5), (6), and (7) are used to obtain it.

[0063] For the patch part, first, the horizontal width W p of the patch is obtained by the following equation (10).

[0064]

Equation

[0065] Next, the effective dielectric constant ε reff is obtained by the following equation (11).

[0066]

Equation

[0067] Then, the calculation variable ΔL is obtained by the following equation (12).

[0068]

Equation

[0069] And the vertical width L p of the patch is obtained by the following equation (13).

[0070]

Equation

[0071] The width g of the notch of the patch is the same as W and is expressed by the following equation (14).

[0072]

number

[0073] The length d of the notch used to adjust the impedance of the patch section is calculated using the following formula (15).

[0074]

number

[0075] <Shape deformation and recovery function> The planar antenna 1 of this embodiment has a shape deformation and recovery function. As described above, the dielectric layer 2 is mainly composed of a shape memory polymer. Therefore, the planar antenna 1 can be deformed into any shape by heating above the temperature transition point of the shape memory polymer and by applying an external force. In addition, the planar antenna 1 can be restored to its original shape by heating above the temperature transition point of the shape memory polymer.

[0076] The temperature transition point of a shape memory polymer corresponds to its glass transition temperature (Tg). The elastic modulus of a shape memory polymer differs significantly around the glass transition temperature (Tg). It becomes relatively higher at temperatures below Tg and relatively lower at temperatures below Tg. The elastic modulus of a shape memory polymer is temperature-dependent.

[0077] Shape memory polymers deform easily with small stresses at temperatures exceeding a predetermined temperature (Tg). In this case, if the maximum strain is kept constant and the polymer is cooled to a temperature below the predetermined temperature (Tg), the stress increases as resistance to thermal shrinkage (recovery stress). If the polymer is unloaded at this low temperature, a residual strain substantially equal to the maximum strain is obtained due to its high modulus of elasticity (shape fixation). On the other hand, if the polymer is heated to a temperature exceeding the predetermined temperature (Tg) under no load from the low-temperature unloaded state, the strain disappears and the polymer returns to its original shape (shape recovery).

[0078] Thus, shape memory polymers possess both shape-retention and shape-recovery properties. Specifically, when a shape memory polymer is cooled below its Tg (temperature above its Globe Temperature) while retaining the shape it was deformed at, it solidifies in that shape. When heated again to a temperature above its Tg, it returns to its stored shape.

[0079] <Effects and Effects> As described above, the planar antenna 1 of this embodiment comprises a ground conductor layer 3, a dielectric layer 2 including a first layer 21 and a second layer 22 arranged outside the ground conductor layer 3 via the ground conductor layer 3, a first antenna conductor layer 4 arranged on the first surface 21a of the first layer 21 opposite to the ground conductor layer 3 and having a first radiating surface 4a, and a second antenna conductor layer 5 arranged on the second surface 22a of the second layer 22 opposite to the ground conductor layer 3 and having a second radiating surface 5a facing away from the first radiating surface 4a. With this configuration, the first radiating surface 4a and the second radiating surface 5a are positioned in opposite directions to each other, allowing for the radiation and reception of radio waves on the first radiating surface 4a and / or the radiation and reception of radio waves on the second radiating surface 5a without changing their orientation. Therefore, a planar antenna 1 can be provided that can radiate and receive radio waves in opposite directions without requiring a change in orientation.

[0080] In this embodiment, the first antenna conductor layer 4 and the second antenna conductor layer 5 have different resonant frequencies. This configuration eliminates the need for actuation (operating the machine using electricity, magnetism, etc.) to change the orientation. In this embodiment, the radiation patterns of the first radiating surface 4a and the second radiating surface 5a can be switched by changing the frequency. Therefore, compared to the case where actuation is provided as described above, the radiation patterns of the first radiating surface 4a and the second radiating surface 5a can be switched in a shorter time.

[0081] In this embodiment, the first antenna conductor layer 4 and the second antenna conductor layer 5 are electrically connected to each other. This configuration simplifies the structure of the planar antenna 1. In this embodiment, the first antenna conductor layer 4 and the second antenna conductor layer 5 are connected to a common feed point 6. Therefore, it is easier to simplify compared to the case where the first antenna conductor layer 4 and the second antenna conductor layer 5 are each connected to separate feed points 6 (where there are two feed points 6).

[0082] In this embodiment, the planar antenna 1 further comprises a branch circuit section 7 having a common section, a first end branching off from the common section to one side, and a second end branching off from the common section to the other side. The first antenna conductor layer 4 comprises a first patch section 40 and a first transmission line section 41 connecting the first end of the branch circuit section 7 to the first patch section 40. The second antenna conductor layer 5 comprises a second patch section 50 and a second transmission line section 51 connecting the second end of the branch circuit section 7 to the second patch section 50. With this configuration, the current from the power supply unit 6 can be guided to the first patch unit 40 through the branch circuit unit 7 and the first transmission line unit 41, and also to the second patch unit 50 through the branch circuit unit 7 and the second transmission line unit 51.

[0083] In this embodiment, the branch circuit section 7 is formed in a T-shape when viewed from above. With this configuration, the branching circuit section 7 ensures that when the microstrip line is branched in three directions, including the original track, all three directions are not affected by reflections from the other two directions.

[0084] In this embodiment, a notch 42 is formed in the first patch portion 40 to shift the resonant frequency. With this configuration, the operating frequency can be switched by shifting the resonant frequency using the notch 42.

[0085] In this embodiment, the planar antenna 1 has a through-hole 8 through which a part of the branching circuit section 7 passes. With this configuration, a portion of the branch circuit section 7 can be guided from the side of the first transmission line section 41 to the side of the second transmission line section 51 through the through hole 8.

[0086] In this embodiment, the dielectric layer 2 is composed mainly of a shape memory polymer. With this configuration, the planar antenna 1 can be deformed into any shape by heating above the temperature transition point of the shape memory polymer and by applying an external force. In addition, the planar antenna 1 can be restored to its original shape by heating above the temperature transition point of the shape memory polymer. Therefore, a planar antenna 1 with shape deformation and recovery functions can be provided.

[0087] In this embodiment, the planar antenna 1 has a dielectric layer 2 mainly composed of a shape memory polymer, giving it shape deformation and recovery capabilities. This provides resistance to deformation, which is a problem with lightweight antennas, and avoids instability in antenna gain. The change in antenna gain due to this deformation becomes more pronounced at higher frequencies, making it effective for antenna design, a fundamental tool in research fields such as Society 5.0 and / or 6.0. Furthermore, by using a two-plane design, switching the radiating surface from 180 degrees to 360 degrees can be achieved simply by switching the frequency, without any actuation. This eliminates the time required for attitude changes and attitude stabilization of observation satellites (e.g., a week's worth of time) in space observation. This means that the number of observations per year can be increased, leading to a significant reduction in observation waiting time for astrophysicists.

[0088] <Second Embodiment> Figure 9 is a plan view of the planar antenna 201 according to the second embodiment, as seen from the first radiating surface 4a side. Figure 10 is a plan view of the planar antenna 201 according to the second embodiment, as seen from the second radiating surface 5a side. The planar antenna 201 according to the second embodiment will now be described with reference to Figures 9 and 10. In the configuration shown in Figures 9 and 10, components similar to those in the above-described embodiment are denoted by the same reference numerals, and their detailed descriptions are omitted.

[0089] At least a portion of the dielectric layer 202 has a hollow structure 225. The hollow structure 225 is a structure formed with air contained inside the dielectric layer 202 and corresponds to a hollowed-out portion of the dielectric layer 202.

[0090] In a plan view, the dielectric layer 202 has a solid structure 226 in a portion that overlaps with at least the first patch portion 40 of the first antenna conductor layer 4. The solid structure 226 is the structure in which the dielectric layer 202 itself exists, and corresponds to the portion of the dielectric layer 202 other than the hollowed-out portion.

[0091] In plan view, a portion of the dielectric layer 202 is square. Specifically, the dielectric layer 202 includes a square portion 202A formed in a square shape in plan view, and a rectangular portion 202B formed in a rectangular shape in plan view. The first patch portion 40 is formed in the square portion 202A. The rectangular portion 202B connects to the +y edge of the square portion 202A in plan view. The rectangular portion 202B extends further outward in both x directions than the square portion 202A in plan view. The branch circuit portion 7 is formed in the rectangular portion 202B. In plan view, at least a portion of the hollow structure 225 is positioned symmetrically four times with respect to the center of the square portion 202A of the dielectric layer 202 as the axis of symmetry.

[0092] As described above, in this embodiment, at least a portion of the dielectric layer 202 has a hollow structure 225. This configuration allows for weight reduction compared to a case where the entire dielectric layer 202 is solid.

[0093] In this embodiment, in a plan view, the dielectric layer 202 has a solid structure 226 in a portion that overlaps with at least the first patch portion 40 of the first antenna conductor layer 4. With this configuration, the dielectric layer 202 has a solid structure 226 in the area where it overlaps with the first patch portion 40 of the first antenna conductor layer 4 in a plan view. Therefore, while accepting a slight reduction in rigidity, the mass can be significantly reduced.

[0094] In this embodiment, in plan view, a portion of the dielectric layer 202 is square. In plan view, at least a portion of the hollow structure 225 is positioned in a position that is symmetrical four times with respect to the center of the square portion 202A of the dielectric layer 202 as the axis of symmetry. This configuration allows for the realization of a more suitable shape for achieving high rigidity and lightweight design as a planar antenna 201.

[0095] <Variation> In the embodiments described above, the first antenna conductor layer and the second antenna conductor layer were described using examples where they have different resonant frequencies, but the invention is not limited to this. For example, the radiation patterns of the first and second radiating surfaces do not necessarily have to be switchable by changing the frequency. For example, the radiation patterns of the first and second radiating surfaces may be switchable by actuation for changing the orientation (operating the machine using electricity, magnetism, etc.). The method of switching the radiation patterns can be changed according to the design specifications.

[0096] In the embodiments described above, the first antenna conductor layer and the second antenna conductor layer were described in an example where they were electrically connected to each other, but the invention is not limited to this. For example, the first antenna conductor layer and the second antenna conductor layer do not have to be connected to a common feeding point. For example, the first antenna conductor layer and the second antenna conductor layer may each be connected to a different feeding point. For example, a planar antenna may have two feeding points. The way in which the first antenna conductor layer and the second antenna conductor layer are connected to the feeding points can be changed according to the design specifications.

[0097] In the embodiments described above, the planar antenna further comprises a branch circuit section having a common section, a first end branching from the common section to one side, and a second end branching from the common section to the other side. The first antenna conductor layer comprises a first patch section and a first transmission line section connecting the first end of the branch circuit section to the first patch section, and the second antenna conductor layer comprises a second patch section and a second transmission line section connecting the second end of the branch circuit section to the second patch section. However, the invention is not limited to this example. For example, the first antenna conductor layer and the second antenna conductor layer may be directly connected to the feed section. For example, the planar antenna does not need to have a branch circuit section. The configuration of the branch circuit section can be changed according to the design specifications.

[0098] In the embodiments described above, the branch circuit section was explained as being formed in a T-shape in plan view, but it is not limited to this. For example, the branch circuit section may be formed in a shape other than a T-shape in plan view. For example, the branch circuit section may be formed in a U-shape in plan view. The plan view shape of the branch circuit section can be changed according to the design specifications.

[0099] In the embodiments described above, an example was given in which a notch is formed in at least one of the first patch portion and the second patch portion to shift the resonant frequency, but the invention is not limited to this. For example, notches may not be formed in the first patch portion and the second patch portion. The manner in which the notches are formed can be changed according to the design specifications.

[0100] In the embodiments described above, an example was given in which a through-hole is formed in the planar antenna to pass through a part of the branching circuit section, but the invention is not limited to this. For example, a part of the branching circuit section may be provided to bypass the planar antenna (dielectric layer, etc.). For example, a through-hole may not be formed in the planar antenna. The manner in which the through-hole is formed can be changed according to the design specifications.

[0101] In the embodiments described above, the dielectric layer was explained using an example in which a shape memory polymer is the main component, but it is not limited to this. For example, the dielectric layer does not have to be composed mainly of a shape memory polymer. The configuration of the dielectric layer can be changed according to the design specifications.

[0102] Although embodiments of the present invention have been described above, the present invention is not limited thereto, and additions, omissions, substitutions, and other modifications to the configuration are possible without departing from the spirit of the invention, and the above embodiments can be combined as appropriate.

[0103] (Note 1) Ground conductor layer, A dielectric layer including a first layer and a second layer disposed outside the ground conductor layer via the ground conductor layer, A first antenna conductor layer is arranged on the first surface of the first layer opposite to the ground conductor layer and has a first radiating surface, The second antenna conductor layer is arranged on the second surface of the second layer opposite to the ground conductor layer and has a second radiating surface facing away from the first radiating surface, Planar antenna.

[0104] (Note 2) The first antenna conductor layer and the second antenna conductor layer have different resonant frequencies. The planar antenna described in Appendix 1.

[0105] (Note 3) The first antenna conductor layer and the second antenna conductor layer are electrically connected to each other. A planar antenna as described in Appendix 1 or 2.

[0106] (Note 4) The system further comprises a common section, a first end branching off from the common section to one side, and a second end branching off from the common section to the other side. The first antenna conductor layer is, The first patch section, The branch circuit section comprises a first transmission line section connecting the first end and the first patch section, The aforementioned second antenna conductor layer is The second patch section, The system includes a second transmission line section that connects the second end of the branch circuit section to the second patch section, A planar antenna as described in Appendix 2 or 3.

[0107] (Note 5) At least one of the first patch portion and the second patch portion has a notch formed in it to shift the resonant frequency. The planar antenna described in Appendix 4.

[0108] (Note 6) The dielectric layer is composed mainly of a shape memory polymer. A planar antenna as described in any of the appendices 1 through 5. [Examples]

[0109] The following will provide a detailed description of the planar antenna according to the above embodiment of the present invention, with reference to specific examples. Note that the following examples are specific examples to which the present invention is applied and do not limit the present invention.

[0110] Figure 11 is a perspective view of the planar antenna of the embodiment. Figure 12 shows the frequency f of the planar antenna of the embodiment. f This is a side view showing the radiation pattern in [location]. Figure 13 shows the frequency f of the planar antenna in the embodiment. b This is a side view showing the radiation pattern. Figure 14 is a diagram showing the analysis results of the relationship between frequency and gain of the planar antenna in the embodiment.

[0111] (Examples) As shown in Figure 11, the planar antenna of the embodiment comprises a ground conductor layer, a dielectric layer including a first layer and a second layer disposed outside the ground conductor layer via the ground conductor layer, a first antenna conductor layer disposed on the first surface of the first layer opposite to the ground conductor layer and having a first radiating surface, and a second antenna conductor layer disposed on the second surface of the second layer opposite to the ground conductor layer and having a second radiating surface facing away from the first radiating surface, wherein the radiation patterns of the first and second radiating surfaces can be switched by changing the frequency, the first and second antenna conductor layers are connected to a common feed point, and the planar antenna further comprises a branching circuit section that distributes the current from the feed point. The first antenna conductor layer comprises a first patch section and a first transmission line section connecting the first end of the branching circuit section to the first patch section. The second antenna conductor layer comprises a second patch section and a second transmission path section connecting the second patch section to a second end different from the first end of the branch circuit section. The branch circuit section is formed in a T-shape in plan view, with a notch formed in the first patch section to shift the resonant frequency, and no notch formed in the second patch section to shift the resonant frequency. The planar antenna has a through hole through which a part of the branch circuit section passes, and the dielectric layer is made mainly of a shape memory polymer (corresponding to the configuration shown in Figure 1).

[0112] (Evaluation results) The gain of a planar antenna was measured through analytical experiments. The evaluation results are shown in Figures 12 to 14.

[0113] Referring to Figures 12 to 14, it was confirmed that, according to the planar antenna of the embodiment, the radiation patterns of the first and second radiating surfaces can be switched by changing the frequency. Furthermore, it was confirmed that in each radiation pattern, the pattern is biased toward the positive (+) side in the y direction (towards the feed point). [Explanation of symbols]

[0114] 1,201…Planar antenna, 2,202…Dielectric layer, 3…Ground conductor layer, 4…First antenna conductor layer, 4a…First radiating surface, 5…Second antenna conductor layer, 5a…Second radiating surface, 6…Feeding section, 7…Branching circuit section, 8…Through-hole, 21…First layer, 21a…First surface, 22…Second layer, 22a…Second surface, 40…First patch section, 41…First transmission line section, 42…Notch, 50…Second patch section, 51…Second transmission line section

Claims

1. Ground conductor layer, A dielectric layer including a first layer and a second layer disposed outside the ground conductor layer via the ground conductor layer, A first antenna conductor layer is arranged on the first surface of the first layer opposite to the ground conductor layer and has a first radiating surface, The second antenna conductor layer is arranged on the second surface of the second layer opposite to the ground conductor layer and has a second radiating surface facing away from the first radiating surface, Planar antenna.

2. The first antenna conductor layer and the second antenna conductor layer have different resonant frequencies. The planar antenna according to claim 1.

3. The first antenna conductor layer and the second antenna conductor layer are electrically connected to each other. A planar antenna according to claim 1 or 2.

4. The system further comprises a common section, a first end branching off from the common section to one side, and a second end branching off from the common section to the other side. The first antenna conductor layer is, The first patch section, The branch circuit section comprises a first transmission line section connecting the first end and the first patch section, The aforementioned second antenna conductor layer is The second patch section, The system includes a second transmission line section that connects the second end of the branch circuit section to the second patch section, The planar antenna according to claim 2.

5. At least one of the first patch portion and the second patch portion has a notch formed in it to shift the resonant frequency. The planar antenna according to claim 4.

6. The dielectric layer is composed mainly of a shape memory polymer. A planar antenna according to claim 1 or 2.

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