Patch antenna

Abstract

To provide a patch antenna that can increase its antenna gain.SOLUTION: A patch antenna according to an aspect of the present invention has: a first dielectric layer having a fluorine-based resin, and a porous inorganic fine particle aggregate filled into the fluorine-based resin and formed of a plurality of inorganic fine particles; and a first patch conductor formed on the first dielectric layer. The relative dielectric constant of the first dielectric layer is 2.5 or less, and the porosity of the first dielectric layer is 30% to 70%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a patch antenna. [Background technology]

[0002] Fifth-generation (5G) mobile communication systems use electromagnetic waves in a higher frequency band (for example, electromagnetic waves in the 28 GHz band, so-called millimeter waves) than those used in previous mobile communication systems. One example of an antenna for millimeter-wave communication is a patch antenna having a dielectric layer and a rectangular flat-plate patch conductor formed on the dielectric layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-51890 Summary of the Invention [Problem to be solved by the invention]

[0004] Millimeter waves have the problem of short propagation distances due to their high degree of directivity and susceptibility to attenuation during propagation, etc. Even when using a patch antenna as an antenna for millimeter-wave communications, high antenna gain is required.

[0005] An object of the present invention is to provide a patch antenna with improved antenna gain. [Means for solving the problem]

[0006] A patch antenna according to one embodiment of the present invention comprises a first dielectric layer having a fluororesin and a porous inorganic microparticle aggregate composed of a plurality of inorganic microparticles filled in the fluororesin, and a first patch conductor formed on the first dielectric layer, wherein the relative dielectric constant of the first dielectric layer is 2.5 or less and the porosity of the first dielectric layer is 30% to 70%. [Effects of the Invention]

[0007] According to the present invention, the antenna gain of a patch antenna can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view of a patch antenna according to a first embodiment. [Figure 2] 1 is a vertical cross-sectional view of a patch antenna according to a first embodiment. [Figure 3] FIG. 10 is a perspective view of a patch antenna according to a second embodiment. [Figure 4] FIG. 10 is a vertical cross-sectional view of a patch antenna according to a second embodiment. [Figure 5] FIG. 10 is a perspective view of a patch antenna according to a third embodiment. [Figure 6] FIG. 10 is a vertical cross-sectional view of a patch antenna according to a third embodiment. [Figure 7] FIG. 10 is a perspective view of a patch antenna according to a fourth embodiment. [Figure 8] FIG. 10 is a vertical cross-sectional view of a patch antenna according to a fourth embodiment. [Figure 9] FIG. 10 is a perspective view of a patch antenna according to a fifth embodiment. [Figure 10] FIG. 10 is a vertical cross-sectional view of a patch antenna according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicated descriptions will be omitted as appropriate.

[0010] The embodiments described below exemplify patch antennas for embodying the technical ideas of the present disclosure, and the present disclosure is not limited to the embodiments described below. Unless otherwise specified, the dimensions, materials, shapes, relative locations, etc. of the components described below are intended for illustration purposes and are not intended to limit the scope of the present disclosure. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity.

[0011] [First embodiment] <Overall structure> The configuration of a patch antenna 1 according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a perspective view illustrating the patch antenna 1 according to this embodiment. Figure 2 is a vertical cross-sectional view of the patch antenna 1 taken along line AA shown in Figure 1. The X direction shown in the figure corresponds to the width direction of the patch antenna 1, the Y direction corresponds to the depth direction of the patch antenna 1, and the Z direction corresponds to the height direction of the patch antenna 1. The X direction, Y direction, and Z direction are perpendicular to one another. Furthermore, any direction within the XY plane may be referred to as an "in-plane direction." The direction along the Z direction may be referred to as a "perpendicular-to-plane direction."

[0012] The patch antenna 1 is an antenna that performs wireless communication by transmitting and receiving electromagnetic waves having a frequency band of 3 GHz to 300 GHz, such as millimeter waves or microwaves, although the frequency band of electromagnetic waves that can be transmitted and received by the patch antenna 1 may be other than these.

[0013] As shown in Figures 1 and 2, the patch antenna 1 has a first dielectric layer 10, a first patch conductor 20, a first ground layer 30, a second ground layer 40, an inner layer 50, and a power supply section 60.

[0014] <First dielectric layer> The first dielectric layer 10 is, for example, a dielectric layer that functions as a substrate for the patch antenna 1. More specifically, the first dielectric layer 10 has a predetermined thickness and is in the form of a sheet extending in an in-plane direction. The first dielectric layer 10 has a first surface (front surface) 11 located on the upper side in the perpendicular direction to the plane, and a second surface (back surface) 12 located on the lower side in the perpendicular direction to the plane.

[0015] The material for the first dielectric layer 10 is preferably a composite material containing a fluorine-based resin and a filler. Examples of fluorine-based resins include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTEF), tetrafluoroethylene-ethylene copolymer (ETFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), and polyvinylidene fluoride (PVDF). These can be used alone or in combination of two or more. PTFE is particularly preferred.

[0016] The fluororesin is preferably "fibrillated (fibrous structured)." It is more preferable that the fibrillated fibers are oriented not only in one direction but in multiple directions. It is particularly preferable that the fibrils are linked to the inorganic fine particle aggregates described below to form a "three-dimensional micromesh structure." When the fluororesin is fibrillated, particularly when a three-dimensional micromesh structure is formed, the composite material can be assured of excellent mechanical strength and dimensional stability. The fibrillation of the fluororesin can be promoted by applying a shear force, for example, but more specifically, it is preferably carried out by multi-stage rolling. The three-dimensional micromesh structure is preferably formed by anti-directional multi-stage rolling.

[0017] Examples of fillers include granular fillers and fibrous fillers. Examples of granular fillers include solid carbon such as carbon black; silicon dioxide (silica) such as porous silica, fused silica, and silica gel; transition metal oxides (including composite oxides) such as titanium oxide (titanium dioxide (titania)), iron oxide, and zirconium oxide (zirconium dioxide (zirconia)); and nitrides of typical elements such as boron nitride and silicon nitride. Examples of fibrous fillers include glass fiber and carbon fiber. These fillers can be used alone or in combination.

[0018] It is preferable to contain, as the filler, "porous inorganic fine particle aggregates formed by aggregating inorganic fine particles having an average primary particle diameter of 5 to 200 nm (hereinafter, sometimes abbreviated as "inorganic fine particle aggregates")." By containing the inorganic fine particle aggregates as the filler, it is possible to ensure good properties such as a dielectric constant and a thermal expansion coefficient. The inorganic fine particle aggregates refer to aggregates formed by the fusion of a plurality of inorganic fine particles, which are porous with voids between the inorganic fine particles.

[0019] Examples of materials for the inorganic fine particles in the inorganic fine particle aggregate include oxides of typical elements such as silicon oxide (e.g., silicon monoxide, silicon dioxide (silica)) and aluminum oxide (alumina) (including composite oxides); transition metal oxides such as titanium oxide (e.g., titanium dioxide (titania)), iron oxide, and zirconium oxide (zirconium dioxide (zirconia)) (including composite oxides); and nitrides of typical elements such as boron nitride and silicon nitride. These may be used alone or in combination of two or more. Among these, oxides of typical elements are preferred, with silicon dioxide (silica) being particularly preferred. Oxides of typical elements can significantly reduce the dielectric constant of the composite material and enable the composite material to be produced at lower cost. The crystallinity of the inorganic fine particles is not particularly limited, but silicon dioxide is typically amorphous.

[0020] The average primary particle diameter of the inorganic fine particles is 5 to 200 nm, preferably 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and preferably 150 nm or less, more preferably 120 nm or less, even more preferably 100 nm or less, particularly preferably 80 nm or less, and most preferably 70 nm or less. Within this range, inorganic fine particle aggregates are less likely to be destroyed even during processing such as mixing, molding, and rolling, and good void spaces can be secured between the inorganic fine particles, making it easier to secure a smooth surface as a plate-shaped composite material. The average primary particle diameter of the inorganic fine particles is a value obtained by measuring particle diameters by direct observation with a scanning electron microscope and averaging the measured values. Specifically, the value is obtained by randomly selecting (100) inorganic fine particles, measuring the particle diameter (the length of the long side of each particle), and averaging the measured particle diameters.

[0021] In the first dielectric layer 10 containing a fluorine-based resin and a filler, the porosity of the first dielectric layer 10 is preferably 30% or more, more preferably 35% or more, even more preferably 40% or more, even more preferably 45% or more, and particularly preferably 50% or more, and is usually 80% or less, preferably 70% or less. Within this range, the composite material can ensure good properties such as relative permittivity and expansion coefficient. The porosity is a value calculated by measuring the bulk density and true density of the material to be the pore-containing layer and substituting them into the following formula: Porosity [%] = (1 - (bulk density [g / cm3] of material containing fluororesin and filler) 3 ] / True density of material containing fluororesin and filler [g / cm 3 ]))×100

[0022] The relative permittivity of the first dielectric layer 10 (frequency: 10 GHz) is usually 2.5 or less, preferably 2.3 or less, more preferably 2.2 or less, even more preferably 2.1 or less, and particularly preferably 2.0 or less, and is usually 1.55 or more. Note that the "relative permittivity" is the value obtained by dividing the "dielectric constant" by the "dielectric constant of a vacuum," which is 1. Therefore, in this specification, "relative permittivity" and "dielectric constant" are treated as synonymous terms.

[0023] The dielectric loss tangent (frequency: 10 GHz) of the first dielectric layer 10 is usually 0.01 or less, preferably 0.0075 or less, more preferably 0.005 or less, even more preferably 0.004 or less, particularly preferably 0.003 or less, and is usually 0.0005 or more.

[0024] The coefficient of linear thermal expansion of the first dielectric layer 10 is typically 70 ppm / K or less, preferably 60 ppm / K or less, more preferably 55 ppm / K or less, even more preferably 50 ppm / K or less, and particularly preferably 45 ppm / K or less, and typically 10 ppm / K or more. The coefficient of linear thermal expansion of the first dielectric layer 10 is defined as the average coefficient of linear thermal expansion from -50 to 200°C, as determined by the TMA (Thermal Mechanical Analysis) method. Specifically, the first dielectric layer 10, measuring 4 mm in width and 20 mm in length, is fixed in the longitudinal direction, a 2 g load is applied, and the layer is heated from room temperature (25°C) to 200°C at a heating rate of 10°C / min and held for 30 minutes to remove residual stress from the material. The layer is then cooled to -50°C at 10°C / min, held for 15 minutes, and then heated to 200°C at 2°C / min. The average coefficient of linear thermal expansion from -50 to 200°C during the second heating process is defined as the coefficient of linear thermal expansion.

[0025] The thickness of the first dielectric layer 10 is not particularly limited, but is preferably 0.05 mm to 1.0 mm. By setting the thickness of the first dielectric layer 10 within this range, a high-gain antenna can be obtained.

[0026] In the first dielectric layer 10, an adhesive layer may be laminated on the layer of the aforementioned composite material having a fluorine-based resin and an inorganic microparticle aggregate composed of a plurality of inorganic microparticles (hereinafter, the layer of the composite material may be referred to as the "substrate layer").

[0027] Although not particularly limited, examples of the material for the pressure-sensitive adhesive layer include an acrylic pressure-sensitive adhesive composition, a silicone pressure-sensitive adhesive composition, a urethane pressure-sensitive adhesive composition, and a rubber pressure-sensitive adhesive composition.

[0028] The thickness of the adhesive layer is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 40 μm or more, and preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. Furthermore, when the thickness of the base layer is taken as 1, the thickness of the adhesive layer after curing (the ratio of the thickness of the base layer to the thickness of the adhesive layer) is preferably 0.01 to 0.1, more preferably 0.05 to 0.7. By setting the thickness of the adhesive layer within this range, it is possible to reduce the difference in level between the surface of the first patch conductor 20 and the surface of the base layer while suppressing the energy loss (dielectric loss) of the electromagnetic wave caused by the adhesive layer. This improves adhesion when an additional covering layer is formed on the surfaces of the first patch conductor 20 and the base layer. Furthermore, when the covering layer is in the form of a flexible sheet, it is possible to reduce the surface undulations when the antenna element is formed, enabling the formation of a patch antenna 1 with low loss.

[0029] <First patch conductor> The first patch conductor 20 is a conductor layer that functions as an antenna element. The first patch conductor 20 is formed on the first surface 11 of the first dielectric layer 10. More specifically, the first patch conductor 20 has a rectangular planar shape, and has a first surface (front surface) 21 located on the upper side in the perpendicular direction, and a second surface (back surface) 22 located on the lower side in the perpendicular direction. However, the shape of the first patch conductor 20 is not limited to this.

[0030] The first patch conductor 20 radiates electromagnetic waves in a predetermined frequency band from the patch antenna 1 toward an external communication device, for example, in response to transmission of high-frequency current from the power supply section 60. In addition, the first patch conductor 20 receives electromagnetic waves in a predetermined frequency band radiated toward the patch antenna 1 from the external communication device, for example.

[0031] 1 and 2, the number of the first patch conductors 20 in this embodiment is one, but the number of the first patch conductors 20 is not limited to this. For example, a plurality of first patch conductors 20 may be arranged in an array on the first surface 11 of the first dielectric layer 10.

[0032] The material of the first patch conductor 20 is not particularly limited, and examples thereof include metals such as titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, platinum, tungsten, zirconium, tantalum, and hafnium; conductive metal oxides such as ITO (oxide of indium and tin), zinc oxide, and tin oxide; and materials containing two or more of these metals or metal oxides, or alloys containing these metals as the main component.

[0033] <First ground layer> 1 and 2, the first ground layer 30 is a sheet-like conductor layer that is joined to the second surface 12 of the first dielectric layer 10 and faces the first patch conductor 20 across the first dielectric layer 10. The first ground layer 30 functions as a reference part for the potential of the first patch conductor 20.

[0034] The material of the first ground layer 30 is not particularly limited as long as it is conductive, and examples thereof include metals such as titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, platinum, tungsten, zirconium, tantalum, and hafnium; conductive metal oxides such as ITO, zinc oxide, and tin oxide; and materials containing two or more of these metals or metal oxides, or alloys containing these metals as the main component.

[0035] 2, a through hole 31 is provided at a predetermined position in the first ground layer 30. A first conductive via 61 of the power supply section 60 is inserted through the through hole 31.

[0036] <Second ground layer> The second ground layer 40 is a sheet-like conductor layer located below the first ground layer 30 in the perpendicular direction. As shown in FIG. 1 , the second ground layer 40 is located near the feed line 62 of the power supply unit 60. When a high-frequency current is transmitted to the power supply unit 60 toward the first patch conductor 20, electromagnetic waves may propagate in the vicinity thereof. If the electromagnetic waves propagating from the power supply unit 60 act on the first patch conductor 20, for example, this may cause a degradation in the antenna performance of the patch antenna 1. According to this embodiment, the provision of the second ground layer 40 prevents a degradation in antenna performance due to the electromagnetic waves from the power supply unit 60. Note that although the second ground layer 40 of this embodiment is located at the bottom of the patch antenna 1, the location of the second ground layer 40 is not limited thereto.

[0037] The material of the second ground layer 40 is not particularly limited as long as it is conductive, and examples thereof include metals such as titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, platinum, tungsten, zirconium, tantalum, and hafnium; conductive metal oxides such as ITO, zinc oxide, and tin oxide; and materials containing two or more of these metals or metal oxides, or alloys containing these metals as the main component.

[0038] <Inner layer> The inner layer 50 is a sheet-like layer extending in an in-plane direction. As shown in Figs. 1 and 2, the inner layer 50 is sandwiched between the first ground layer 30 and the second ground layer 40. The inner layer 50 has a first surface (front surface) 51 located on the upper side in the perpendicular direction and a second surface (back surface) 52 located on the lower side in the perpendicular direction. A power supply line 62 of the power supply unit 60 is formed on the second surface 52 of the inner layer 50.

[0039] The material of the inner layer 50 is not particularly limited, but examples include polymeric materials such as polyethylene resin, polypropylene resin, and polystyrene resin; and insulating materials such as ceramic materials.

[0040] <Power supply unit> The power supply unit 60 transmits a high-frequency current to the first patch conductor 20. More specifically, the power supply unit 60 has a first conductive via 61 that penetrates the first dielectric layer 10, the first ground layer 30, and the inner layer 50, and a power supply line 62 that is electrically connected to the first conductive via 61 and is formed on the second surface 52 of the inner layer 50. The first conductive via 61 is also electrically connected to the first patch conductor 20. The power supply line 62 is also electrically connected to a power source, a signal processing unit, etc.

[0041] <Effects of the first embodiment> The patch antenna 1 of this embodiment includes a first dielectric layer 10 that contains a fluorine-based resin and an inorganic fine particle aggregate and has a porosity of 30% to 70%. This allows the dielectric constant of the first dielectric layer 10 to be reduced, improving the antenna gain of the patch antenna 1. The first dielectric layer 10 also contains an inorganic fine particle aggregate as a filler. In addition to the low dielectric property of the first dielectric layer 10, other properties such as the thermal expansion coefficient can be improved. As a result, the reliability of the patch antenna 1 can be improved.

[0042] [Second embodiment] <Overall structure> Next, a patch antenna 1A according to a second embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a perspective view illustrating the patch antenna 1A according to the present embodiment. Fig. 4 is a vertical cross-sectional view of the patch antenna 1A taken along line BB shown in Fig. 3.

[0043] 3 and 4, the patch antenna 1A further includes a plurality of second conductive vias 70. Each of the second conductive vias 70 is disposed near the first patch conductor 20 and passes through the first dielectric layer 10. Each of the second conductive vias 70 is electrically connected to the first ground layer 30.

[0044] <Effects of the second embodiment> When multiple first patch conductors 20 are arranged in an array on the first dielectric layer 10, the first patch conductors 20 are mounted at high density on the first dielectric layer 10 from the viewpoint of, for example, miniaturizing the antenna. As a result, adjacent first patch conductors 20 are brought close to each other, and if the electromagnetic coupling between them becomes strong, the antenna characteristics are affected. In contrast, according to the present embodiment, multiple second conductive vias 70 are arranged between adjacent first patch conductors 20, and therefore the electromagnetic coupling between the first patch conductors 20 is weakened even if multiple first patch conductors 20 are mounted at high density. As a result, it is possible to prevent a deterioration in the antenna characteristics.

[0045] Note that, although the multiple second conductive vias 70 in this embodiment are arranged to surround the periphery of the first patch conductor 20, this is not limitative. Furthermore, the number of second conductive vias 70 is not limited.

[0046] [Third embodiment] <Overall structure> Next, a patch antenna 1B according to a third embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a perspective view illustrating the patch antenna 1B according to the present embodiment. Fig. 6 is a vertical cross-sectional view of the patch antenna 1B taken along line CC shown in Fig. 5.

[0047] The patch antenna 1B has a second dielectric layer 80 formed on the first patch conductor 20. The second dielectric layer 80 is a dielectric layer that covers at least the first surface 21 of the first patch conductor 20. More specifically, the second dielectric layer 80 has a predetermined thickness and is in the form of a sheet extending in the in-plane direction. The second dielectric layer 80 also has a first surface (front surface) 81 located on the upper side in the perpendicular direction and a second surface (back surface) 82 located on the lower side in the perpendicular direction. As shown in FIGS. 5 and 6 , the second dielectric layer 80 of this embodiment covers not only the first surface 21 of the first patch conductor 20 but also a region of the first surface 11 of the first dielectric layer 10 where the first patch conductor 20 is not formed.

[0048] The relative dielectric constant of the second dielectric layer 80 is preferably 3.5 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. The relative dielectric constant of the second dielectric layer 80 is preferably 1.2 or more. By setting the relative dielectric constant within the above range, the second dielectric layer 80 interacts with the second dielectric layer 80, which has a low dielectric constant, to increase the directionality of the radiated electromagnetic wave while suppressing reflection loss at the air interface of the electromagnetic wave radiated from the first patch conductor 20. This allows the second dielectric layer 80 to behave like a lens, thereby achieving high gain for the patch antenna 1. In this case, the relative dielectric constant of the second dielectric layer 80 may be uniform in the thickness direction or in the in-plane direction.

[0049] The dielectric loss tangent (frequency: 10 GHz) of the second dielectric layer 80 is usually 0.01 or less, preferably 0.0075 or less, more preferably 0.005 or less, even more preferably 0.004 or less, particularly preferably 0.003 or less, and is usually 0.0005 or more.

[0050] An example of the second dielectric layer 80 having a low dielectric constant is a fluororesin such as polytetrafluoroethylene. The material of the second dielectric layer 80 may also be a composite material containing a fluororesin and a filler similar to those of the first dielectric layer 10. The fluororesin and filler contained in the second dielectric layer 80 may be the same as the above-mentioned fluororesin and filler usable in the first dielectric layer 10. However, the material of the second dielectric layer 80 is not limited to this.

[0051] When the second dielectric layer 80 contains, for example, a fluorine-based resin and a filler, similar to the first dielectric layer 10, the porosity of the second dielectric layer 80 is preferably 30% or more, more preferably 35% or more, even more preferably 40% or more, even more preferably 45% or more, and particularly preferably 50% or more, and is usually 80% or less, preferably 70% or less. Within this range, favorable properties such as the relative dielectric constant and expansion coefficient of the composite material can be ensured. As with the first dielectric layer 10, the porosity is a value calculated by measuring the bulk density and true density of the material to be the pore-containing layer and substituting them into the following formula: Porosity [%] = (1 - (bulk density [g / cm3] of material containing fluororesin and filler) 3 ] / True density of material containing fluororesin and filler [g / cm 3 ]))×100

[0052] The thickness of the second dielectric layer 80 is preferably 1.0 mm or more, more preferably 3.0 mm or more, and even more preferably 5.0 mm or more. The thickness of the second dielectric layer 80 is preferably 10 mm or less. By setting the thickness of the second dielectric layer 80 within this range, the antenna gain can be further improved. <Effects of the third embodiment>

[0053] By using, for example, a dielectric layer having the above-described fluorine-based resin and filler as the second dielectric layer 80, it is possible to improve the antenna gain of the patch antenna 1. In addition, by reducing the expansion coefficient of the second dielectric layer 80, it is possible to prevent, for example, breakage, peeling, and the like caused by the difference in expansion coefficient with that of the first patch conductor 20.

[0054] [Fourth embodiment] <Overall structure> Next, a patch antenna 1C according to a fourth embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a perspective view illustrating the patch antenna 1C according to this embodiment. Fig. 8 is a vertical cross-sectional view of the patch antenna 1C taken along line DD shown in Fig. 7.

[0055] The patch antenna 1C further includes a second patch conductor 90 formed on the first surface 81 of the second dielectric layer 80. As shown in FIG. 8, the second patch conductor 90 faces the first patch conductor 20 across the second dielectric layer 80. The second patch conductor 90 is When a high-frequency current is transmitted from the power supply unit 60, the second patch conductor 90 is electromagnetically coupled to the first patch conductor 20 and is fed with power from the first patch conductor 20. As a result, for example, the second patch conductor 90 radiates electromagnetic waves in a predetermined frequency band toward an external communication device. Also, for example, the second patch conductor 90 receives electromagnetic waves in a predetermined frequency band radiated toward the patch antenna 1 from the external communication device.

[0056] 7 and 8, the number of second patch conductors 90 in this embodiment is one, but is not limited to this. For example, a plurality of second patch conductors 90 may be arranged in an array on the first surface 81 of the second dielectric layer 80.

[0057] The material of the second patch conductor 90 is not particularly limited, and examples thereof include metals such as titanium, silicon, niobium, indium, zinc, tin, gold, silver, copper, aluminum, cobalt, chromium, nickel, lead, iron, palladium, platinum, tungsten, zirconium, tantalum, and hafnium; conductive metal oxides such as ITO (oxide of indium and tin), zinc oxide, and tin oxide; and materials containing two or more of these metals or metal oxides, or alloys containing these metals as the main component.

[0058] <Effects of the Fourth Embodiment> According to this embodiment, by providing a second patch conductor 90 that faces the first patch conductor 20 across the second dielectric layer 80 and is electromagnetically coupled to the first patch conductor 20, the antenna performance (e.g., antenna gain and frequency bandwidth) of the patch antenna 1C can be improved.

[0059] [Fifth embodiment] <Overall structure> Next, a patch antenna 1D according to a fifth embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a perspective view illustrating the patch antenna 1D according to this embodiment. Fig. 10 is a vertical cross-sectional view of the patch antenna 1D taken along the E-E line shown in Fig. 9.

[0060] The patch antenna 1D further includes a conductive pattern 100 formed on the first surface 81 of the second dielectric layer 80. An example of the conductive pattern 100 is one having a so-called metasurface structure that includes periodically arranged unit patterns. As shown in FIGS. 9 and 10 , the conductive pattern 100 of this embodiment includes unit patterns 101 that are made of thin metal wires having a circular planar shape. However, the shape and size of each unit pattern 101 and the distance (pitch) between adjacent unit patterns 101 may be adjusted as appropriate depending on the desired characteristics.

[0061] <Effects of the Fifth Embodiment> According to this embodiment, by providing the conductive pattern 100 on the second dielectric layer 80, it is possible to control the transmission characteristics of electromagnetic waves that pass through the surface (for example, the first surface 81) of the second dielectric layer 80. This makes it possible to radiate electromagnetic waves with high antenna gain in directions other than the normal direction (the straight line perpendicular to the first surface 81 of the second dielectric layer 80) of the patch antenna 1D according to this embodiment.

[0062] Aspects of the present disclosure are, for example, as follows. <1> a first dielectric layer including a fluororesin and a porous inorganic fine particle aggregate filled with the fluororesin and composed of a plurality of inorganic fine particles; a first patch conductor formed on the first dielectric layer; and The first dielectric layer has a relative dielectric constant of 2.5 or less, The porosity of the first dielectric layer is 30% to 70%. Patch antenna. <2> The first dielectric layer has a coefficient of linear thermal expansion of 50 ppm / K or less. The aforementioned <1> The patch antenna according to claim 1. <3> the first dielectric layer has a base layer and a pressure-sensitive adhesive layer formed on the base layer, the thickness ratio of the base layer to the pressure-sensitive adhesive layer is 0.01 to 0.1; The aforementioned <1> or the above <2> The patch antenna according to claim 1. <4> a ground layer facing the first patch conductor with the first dielectric layer interposed therebetween; a plurality of second conductive vias that penetrate the first dielectric layer, are electrically connected to the ground layer, and are disposed near the first patch conductor; Further comprising: The aforementioned <1> From the above <3> 10. A patch antenna according to claim 9, wherein: <5> further comprising a second dielectric layer formed on the first patch conductor; The aforementioned <1> From the above <4> 10. A patch antenna according to claim 9, wherein: <6> a feeding portion having a first conductive via that penetrates the first dielectric layer and has one end electrically connected to the first patch conductor; a second patch conductor formed on the second dielectric layer; and the second patch conductor is electromagnetically coupled to the first patch conductor; Power is fed from the feeding portion to the second patch conductor via the first patch conductor. The aforementioned <5> The patch antenna according to claim 1. <7> Further comprising a conductive pattern having a plurality of unit patterns formed on the second dielectric layer. The aforementioned <5> or the above <6> The patch antenna according to claim 1. [Explanation of symbols]

[0063] 1,1A,1B,1C,1D Patch antenna 10 First dielectric layer 20 First patch conductor 30 First Ground Layer 40 Second Ground Layer 50 inner layer 60 Power supply unit 61 First conductive via 62 Feed line 70 Second conductive via 80 Second dielectric layer 90 Second patch conductor 100 Conductor Pattern 101 Conductor pattern unit pattern

Claims

1. a first dielectric layer including a fluororesin and a porous inorganic fine particle aggregate formed by aggregating a plurality of inorganic fine particles filled in the fluororesin; a first patch conductor formed on the first dielectric layer; and the first dielectric layer has a relative dielectric constant of 2.5 or less; The porosity of the first dielectric layer is 30% to 70%. Patch antenna.

2. The first dielectric layer has a coefficient of linear thermal expansion of 50 ppm / K or less. The patch antenna of claim 1 .

3. the first dielectric layer has a base layer and an adhesive layer formed on the base layer, the thickness ratio of the base layer to the pressure-sensitive adhesive layer is 0.01 to 0.1; 3. The patch antenna according to claim 1 or 2.

4. a ground layer facing the first patch conductor with the first dielectric layer interposed therebetween; a plurality of second conductive vias that penetrate the first dielectric layer, are electrically connected to the ground layer, and are arranged near the first patch conductor; Further comprising:

3. The patch antenna according to claim 1 or 2.

5. a second dielectric layer formed on the first patch conductor; 3. The patch antenna according to claim 1 or 2.

6. a feeding portion having a first conductive via that penetrates the first dielectric layer and has one end electrically connected to the first patch conductor; a second patch conductor formed on the second dielectric layer; and the second patch conductor is electromagnetically coupled to the first patch conductor; power is fed from the feeding portion to the second patch conductor via the first patch conductor; The patch antenna according to claim 5 .

7. Further comprising a conductive pattern having a plurality of unit patterns formed on the second dielectric layer. The patch antenna according to claim 5 .

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