Antenna element and antenna module

Abstract

This antenna element includes a dielectric, a first radiation conductor, a second radiation conductor, a frame-shaped conductor, a ground conductor, and a power supply conductor. The first radiation conductor, the second radiation conductor, and the ground conductor are sequentially positioned in a thickness direction of the dielectric and face each other. The second radiation conductor is connected to the power supply conductor. The frame-shaped conductor surrounds the second radiation conductor in a planar perspective view in the thickness direction of the dielectric, and is located between the first radiation conductor and the ground conductor in the thickness direction of the dielectric.

Description

Antenna element and antenna module

[0001] The present disclosure relates to an antenna element and an antenna module.

[0002] WO 2019 / 054094 discloses an antenna module in which ground via conductors are provided between patch antennas.

[0003] The frequency bands newly allocated for 5G (fifth generation mobile communication systems) are relatively wideband. A stacked patch antenna is known as a patch antenna capable of outputting wideband radio waves.

[0004] The antenna element according to the present disclosure comprises a dielectric, a first radiation conductor, a second radiation conductor, a frame-shaped conductor, a ground conductor, and a feed conductor, wherein the first radiation conductor, the second radiation conductor, and the ground conductor are positioned in that order in the thickness direction of the dielectric and face each other, the second radiation conductor is connected to the feed conductor, the frame-shaped conductor surrounds the second radiation conductor in a planar perspective view in the thickness direction of the dielectric, and the frame-shaped conductor is positioned between the first radiation conductor and the ground conductor in the thickness direction of the dielectric.

[0005] The antenna module according to the present disclosure includes the antenna element described above and an integrated circuit.

[0006] 3. A perspective view of the antenna element of the present embodiment. A perspective view of the antenna element of the present embodiment. A planar perspective view of the antenna element of the present embodiment as seen from above. A cross-sectional view taken along the line (iv)-(iv) in FIG. 3. A cross-sectional view of another example of the antenna element of the present embodiment. A cross-sectional view of another example of the antenna element of the present embodiment. A cross-sectional view of another example of the antenna element of the present embodiment. A cross-sectional view of another example of the antenna element of the present embodiment. A diagram showing the results of an electromagnetic field simulation (Sim1) of a stacked patch antenna in which the dielectric and ground conductor are large relative to the radiating conductor. A radiation pattern diagram of Sim1. A diagram showing the results of an electromagnetic field simulation (Sim3) of the antenna element of the present embodiment in which the dielectric and ground conductor are large relative to the radiating conductor. A radiation pattern diagram of Sim3. A graph showing the change in zenith gain of the antenna element when the position of the frame-shaped conductor is changed in the vertical direction. A cross-sectional view of the antenna module of the present embodiment.

[0007] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings.

[0008] 1 and 2 are perspective views of the antenna element of this embodiment. FIG. 3 is a planar perspective view of the antenna element of this embodiment as seen from above. FIG. 4 is a cross-sectional view taken along line (iv)-(iv) in FIG. 3. Hereinafter, the Z direction in the drawings will be referred to as the vertical direction, and the X and Y directions perpendicular to the Z direction as the horizontal directions. The Z direction is perpendicular to the surface of the ground conductor 6 when viewed from the first radiation conductor 3 or the second radiation conductor 4, and corresponds to the thickness direction of the dielectric 2. To make the arrangement of each conductor easier to understand, the perspective view of FIG. 2 is enlarged six times in the Z direction, with the dielectric 2 being transparent, to show only the conductors, compared to the perspective view of FIG. 1. In FIG. 3, "planar perspective" refers to a perspective view looking vertically downward (in the Z direction). The X and Y directions are two mutually orthogonal directions along the top surface of the ground conductor 6. The up, down, left, and right directions in this specification may differ from the up, down, left, and right directions when the antenna element 1 is in use.

[0009] <Basic Configuration> The antenna element 1 of this embodiment includes a dielectric 2, a first radiation conductor 3, a second radiation conductor 4, a frame-shaped conductor 5, a ground conductor 6, and a feed conductor 7. The "radiation conductor" refers to a conductor that has the function of radiating radio waves into space. The radiation conductor may be a conductive plate or a conductive film.

[0010] The first radiation conductor 3, the second radiation conductor 4, and the ground conductor 6 are positioned in this order in the Z direction and face each other. That is, the first radiation conductor 3, the second radiation conductor 4, and the ground conductor 6 may face each other with a part of the dielectric 2 sandwiched between them.

[0011] The second radiation conductor 4 is connected to the feed conductor 7. The feed conductor 7 may be connected to a position offset in one direction from the center of the second radiation conductor 4. The feed conductor 7 is connected to a position offset in the −X direction from the center of the second radiation conductor 4. The feed conductor 7 may transmit power corresponding to a transmission signal to the second radiation conductor 4. The feed conductor 7 may also transmit a signal received by the antenna element 1. The feed conductor 7 may extend in the vertical direction via a through hole in the ground conductor 6 and be connected to the second radiation conductor 4.

[0012] 3, in order to clarify the positional relationship between the second radiation conductor 4 and the frame-shaped conductor 5, the frame-shaped conductor 5 and other components located inside the dielectric 2 are indicated by dashed lines. In a planar perspective view in the Z direction, the frame-shaped conductor 5 surrounds the second radiation conductor 4. In addition, the frame-shaped conductor 5 is located between the first radiation conductor 3 and the ground conductor 6 in the Z direction.

[0013] That is, the second radiation conductor 4 and the frame-shaped conductor 5 are located inside the dielectric 2. The first radiation conductor 3 and the ground conductor 6 may be located inside the dielectric 2 or on the surface of the dielectric 2.

[0014] The top surface of the ground conductor 6 may extend in the XY plane. The first radiation conductor 3 and the second radiation conductor 4 may be flat. In this case, one plate surface of the first radiation conductor 3 and one plate surface of the second radiation conductor 4 may be positioned opposite the top surface of the ground conductor 6 in the Z direction. In other words, in a planar perspective view, the first radiation conductor 3, the second radiation conductor 4, and the ground conductor 6 may overlap. The term "plate surface" refers to two outer surfaces that are wider than the others.

[0015] The material of the dielectric 2 may be ceramic or resin. The ceramic may be an aluminum oxide sintered body, a glass ceramic sintered body, a mullite sintered body, an aluminum nitride sintered body, or the like. The resin may be a phenol resin, an epoxy resin, a polyimide resin, or a composite material of these resins with a base material, such as a glass-epoxy composite material.

[0016] The dielectric 2 may be a laminate of multiple dielectric layers. When the second radiation conductor 4 and the frame-shaped conductor 5 are located inside the dielectric 2, the second radiation conductor 4 and the frame-shaped conductor 5 may be located between the dielectric layers. The number of dielectric layers is not limited to one, and may be multiple. When there are multiple dielectric layers, the thicknesses of the dielectric layers do not have to be the same. The position of the frame-shaped conductor 5 in the Z direction can be set by combining the number of dielectric layers and their thicknesses. The materials of each dielectric layer may be different or the same.

[0017] 5 is a cross-sectional view of an example of the antenna element of this embodiment when the dielectric 2 has a two-layer structure. The dielectric layer may include two layers: a first dielectric layer 2a1 located between the first radiation conductor 3 and the second radiation conductor 4, and a second dielectric layer 2a2 located between the second radiation conductor 4 and the ground conductor 6. The first dielectric layer 2a1 is laminated on the second dielectric layer 2a2, and the second radiation conductor 3 is located between the first dielectric layer 2a1 and the second dielectric layer 2a2. The first radiation conductor may be located on the upper surface of the first dielectric layer 2a1. The ground conductor 6 may be located on the lower surface of the second dielectric layer 2a2. One end of the feed conductor 7 may be connected to the second radiation conductor 4, and the feed conductor 7 may extend through the second dielectric layer 2a2 in the Z direction to the lower surface of the second dielectric layer 2a2. The frame-shaped conductor 5 may be located between the first dielectric layer 2a1 and the second dielectric layer 2a2. In this case, the frame-shaped conductor 5 is located between the first radiation conductor 3 and the ground conductor 6 in the thickness direction of the dielectric 2, at the same position as the second radiation conductor 3. The antenna element 1 may further include a dielectric layer below the ground conductor 6. In this case, the feed conductor 7 may extend to the lower surface of this lower dielectric layer.

[0018] 6 is a cross-sectional view of an example of the antenna element of this embodiment when the dielectric 2 has a three-layer structure. The dielectric layer may include a first dielectric layer 2a1 located between the first radiation conductor 3 and the second radiation conductor 4, and a second dielectric layer 2a2 located between the second radiation conductor 4 and the ground conductor 6. The first dielectric layer 2a1 may be composed of two first dielectric layers 2a1. That is, the dielectric 2 may be formed by stacking two first dielectric layers 2a1 and one second dielectric layer 2a2. Two first dielectric layers 2a1 are stacked on the second dielectric layer 2a2, and the second radiation conductor 4 is located between the first dielectric layer 2a1 and the second dielectric layer 2a2. The first radiation conductor may be located on the upper surface of the upper first dielectric layer 2a1. The ground conductor 6 may be located on the lower surface of the second dielectric layer 2a2. The feed conductor 7 may have one end connected to the second radiation conductor 4, penetrate the second dielectric layer 2a2 in the Z direction, and extend to the lower surface of the second dielectric layer 2a2. The frame conductor 5 may be located between the two first dielectric layers 2a1. In this case, the frame conductor 5 is located between the first radiation conductor 3 and the ground conductor 6, and between the first radiation conductor 3 and the second radiation conductor 4, in the thickness direction of the dielectric 2. In the example of FIG. 6 , the two first dielectric layers 2a1 have the same thickness, so the frame conductor 5 is located at a height intermediate between the first radiation conductor 3 and the second radiation conductor 4 in the thickness direction of the dielectric 2. By making the thicknesses of the two first dielectric layers 2a1 different, the height position of the frame conductor 5 between the first radiation conductor 3 and the second radiation conductor 4 can be set by combining them. The antenna element 1 may further include a dielectric layer below the ground conductor 6. In this case, the feed conductor 7 may extend to the lower surface of the lower dielectric layer.

[0019] 7 is a cross-sectional view of another example of the antenna element of this embodiment, in which the dielectric 2 has a three-layer structure. The dielectric layer may include a first dielectric layer 2a1 located between the first radiation conductor 3 and the second radiation conductor 4, and a second dielectric layer 2a2 located between the second radiation conductor 4 and the ground conductor 6. The second dielectric layer 2a2 may be composed of two second dielectric layers 2a2. That is, the dielectric 2 may be formed by stacking one first dielectric layer 2a1 and two second dielectric layers 2a2. One first dielectric layer 2a1 is stacked on the stacked second dielectric layers 2a2, and the second radiation conductor 4 is located between the upper first dielectric layer 2a1 and the second dielectric layer 2a2. The first radiation conductor may be located on the upper surface of the first dielectric layer 2a1. The ground conductor 6 may be located on the lower surface of the second dielectric layer 2a2. The feed conductor 7 may have one end connected to the second radiation conductor 4, penetrate the two second dielectric layers 2a2 in the Z direction, and extend to the lower surface of the lower second dielectric layer 2a2. The frame conductor 5 may be located between the two second dielectric layers 2a2. In this case, the frame conductor 5 is located between the first radiation conductor 3 and the ground conductor 6, and between the second radiation conductor 3 and the ground conductor 6, in the thickness direction of the dielectric 2. In the example of FIG. 7 , the thickness of the lower second dielectric layer 2a2 is greater than the thickness of the upper second dielectric layer 2a2, so the frame conductor 5 is located closer to the second radiation conductor 4 between the second radiation conductor 4 and the ground conductor 6. The height position of the frame conductor 5 between the second radiation conductor 4 and the ground conductor 6 can be set by varying the thicknesses of the two second dielectric layers 2a2 and combining them. The antenna element 1 may further include a dielectric layer below the ground conductor 6. In this case, the power supply conductor 7 may extend to the lower surface of the underlying dielectric layer.

[0020] The first radiation conductor 3, the second radiation conductor 4, the frame conductor 5, the ground conductor 6, and the power supply conductor 7 may be made of a metal such as tungsten, molybdenum, manganese, copper, silver, palladium, gold, platinum, nickel, or cobalt. The first radiation conductor 3, the second radiation conductor 4, the frame conductor 5, the ground conductor 6, and the power supply conductor 7 may be made of an alloy containing any of the above metals. The first radiation conductor 3, the second radiation conductor 4, the frame conductor 5, the ground conductor 6, and the power supply conductor 7 may be made of different materials or the same materials.

[0021] The first radiation conductor 3 and the second radiation conductor 4 may be metallized conductive films. The power supply conductor 7 may be a via conductor solidified when the dielectric 2 is fired. When the dielectric 2 is a resin substrate, the first radiation conductor 3 and the second radiation conductor 4 may be copper foil. The power supply conductor 7 may be a conductor formed by filling a via hole in a resin substrate with plating.

[0022] <First Radiation Conductor and Second Radiation Conductor> The shapes of the first radiation conductor 3 and the second radiation conductor 4 in planar perspective may be quadrilateral, rectangular, or square. The thickness and size of the first radiation conductor 3 and the second radiation conductor 4 may be adjusted appropriately depending on the target frequency band. In planar perspective, the centers of the first radiation conductor 3 and the second radiation conductor 4 may coincide with each other.

[0023] In the antenna element 1, the second radiation conductor is fed with power via the feed conductor 7 in response to a transmission signal in the target frequency band. This causes resonance between the first radiation conductor 3 and the second radiation conductor 4. Radio waves are then radiated from the first radiation conductor 3 and the second radiation conductor 4, respectively, and the antenna element 1 transmits a signal in the target frequency band.

[0024] The antenna element 1 receives a signal in a target frequency band from the outside world, which causes resonance between the first radiation conductor 3 and the second radiation conductor 4, and the received signal is sent from the second radiation conductor 4 to the feed conductor 7. The "target frequency band" refers to the frequency band that the antenna element 1 is intended to transmit or receive.

[0025] The basic configuration of the antenna element 1 of this embodiment is a stacked patch antenna including a first radiation conductor 3, a second radiation conductor 4, a ground conductor 6, and a feed conductor 7. The stacked patch antenna has, for example, a first resonant frequency due to the first radiation conductor 3 and a higher second resonant frequency due to the second radiation conductor 4. By designing the band due to the first resonance and the band due to the second resonance to partially overlap each other, an antenna with a wide bandwidth can be obtained.

[0026] The resonant frequency of the radiation conductor can be adjusted by the material, size, etc. of the radiation conductor. The resonant frequency of the radiation conductor can also be adjusted by the material, etc. of the dielectric.

[0027] (Frame-Shaped Conductor) In a planar perspective view (XY plane), as shown in Fig. 3 , the frame-shaped conductor 5 continuously surrounds the second radiation conductor 4 without any gaps. In addition, in the Z direction, the frame-shaped conductor 5 is located between the first radiation conductor 3 and the ground conductor 6. In the Z direction, the positions of the frame-shaped conductor 5 and the second radiation conductor 4 may be the same. In other words, the frame-shaped conductor 5 may be located on the same plane as the second radiation conductor 4.

[0028] The shape of the outer periphery and inner periphery of the frame-shaped conductor 5 in planar perspective may be quadrilateral, rectangular, or square. That is, the shape of the frame-shaped conductor 5 in planar perspective may be a square ring. The distance between the outer periphery and inner periphery of the frame-shaped conductor 5 in planar perspective, i.e., the width, may be adjusted as appropriate. The width of the frame-shaped conductor 5 may be uniform. The shapes of the outer periphery and inner periphery of the frame-shaped conductor 5 may both be square, and the frame-shaped conductor 5 may be a square frame with a constant width.

[0029] The thickness of the frame-shaped conductor 5 may be the same as the thickness of the second radiation conductor 4. When the frame-shaped conductor 5 is located on the same plane as the second radiation conductor 4 and the frame-shaped conductor 5 and the second radiation conductor 4 have the same thickness, the formation process is easy.

[0030] <Increasing the size of the antenna and zenith gain> A stacked patch antenna may be connected to an integrated circuit to control the power supply, etc. For example, an integrated circuit element is mounted on the surface of the substrate of the dielectric 2 opposite to the first radiation conductor 3, and the integrated circuit is connected to the feed conductor 7 of the antenna element 1, etc. In this case, if the dimensions of the dielectric 2 and the ground conductor 6 in the planar direction are increased to mount the integrated circuit element, the electric field may spread in the planar direction within the dielectric 2, resulting in a decrease in the gain in the zenith direction.

[0031] An electromagnetic field simulation was performed under the following conditions to confirm the radiation pattern and zenith gain. Unless otherwise specified, it is assumed below that the electromagnetic field simulation was performed under the following conditions. Target frequency band: 64 GHz band (specifically, within the range of 57 to 71 GHz) Wavelength λ of the signal in the target frequency band: 1.96 mm Relative dielectric constant of the dielectric 2: 5.7 Shape of the first radiation conductor 3 and the second radiation conductor 4 in planar perspective: squares of the same size Length A of one side of the first radiation conductor 3 and the second radiation conductor 4: 0.71 mm Distance B between the centers of the thickness of the ground conductor 6 and the first radiation conductor 3: 0.45 mm Distance C between the centers of the thickness of the ground conductor 6 and the second radiation conductor 4: 0.25 mm

[0032] In the simulation model, a stacked patch antenna having the above dimensions is positioned at the center of a substrate having the following dimensions in a plan view. Note that the "substrate dimensions" below refer to the dimensions of the dielectric 2 and the ground conductor 6 in the X and Y directions. Sim1: No frame-shaped conductor, substrate dimensions 10 mm x 10 mm Sim2: No frame-shaped conductor, substrate dimensions 2.1 mm x 2.1 mm Sim3: No frame-shaped conductor, substrate dimensions 15 mm x 15 mm The antenna elements Sim1, Sim2, and Sim3 have a configuration in which the frame-shaped conductor 5 is removed from antenna element 1 shown in Figure 4.

[0033] FIG. 8 shows the results of an electromagnetic field simulation of the stacked patch antenna of Sim1.

[0034] FIG. 9 is a radiation pattern diagram of Sim1. As shown in FIGS. 8 and 9 , in a stacked patch antenna in which the dielectric 2 and ground conductor 6 are larger than the radiation conductor, the electric field propagates horizontally through the dielectric 2 to the side. Therefore, radio waves are radiated not only vertically (toward the zenith) but also obliquely and horizontally relative to the first radiation conductor 3, which tends to reduce the zenith gain. When the dimensions of the dielectric 2 and ground conductor 6 in the XY directions are 2.1 mm × 2.1 mm (Sim2), the zenith gain is 6.2 dBi (not shown). However, when the dimensions of the dielectric 2 and ground conductor 6 in the XY directions are 10 mm × 10 mm (Sim1), the zenith gain is reduced to 5.8 dBi. When the dimensions of the dielectric 2 and ground conductor 6 in the XY directions are 15 mm × 15 mm (Sim3), the zenith gain is further reduced to 3.8 dBi (not shown).

[0035] <Function of Frame-Shaped Conductor> In the antenna element 1 of this embodiment, radiated radio waves are radiated from the second radiation conductor 4, and an electric field propagates to the frame-shaped conductor 5. Reflection occurs in the frame-shaped conductor 5, and reflected radio waves are radiated. It is thought that the reflected radio waves and radiated radio waves overlap and cancel each other out, thereby reducing the spread of radiated radio waves into the dielectric 2.

[0036] Under the above conditions, except for the presence or absence of a frame-shaped conductor and the antenna dimensions, electromagnetic field simulations were performed using the following simulation models to confirm the radiation pattern and zenith gain. Sim4: with frame-shaped conductor, board dimensions 10 mm x 10 mm Sim5: with frame-shaped conductor, board dimensions 15 mm x 15 mm The antenna element of Sim4 has the same configuration as the antenna element 1 shown in Figure 4, i.e., it is the antenna element 1 in which a frame-shaped conductor 5 is added to the antenna element of Sim1. Furthermore, the antenna element of Sim5 is the antenna element 1 in which a frame-shaped conductor 5 is added to the antenna element of Sim3. The width D of the frame-shaped conductor 5 is 1.47 mm (3λ / 4), and the distance E between the frame-shaped conductor 5 and the second radiation conductor 4 is 0.49 mm (λ / 4). The positions of the frame-shaped conductor 5 and the second radiation conductor 4 in the Z direction are the same. Furthermore, the outer and inner peripheries of the frame-shaped conductor 5 in planar perspective are square, and the width of the frame-shaped conductor 5 is uniform.

[0037] Figure 10 shows the results of an electromagnetic field simulation of an antenna element (Sim4) of this embodiment, in which the dielectric and ground conductors are large relative to the radiation conductor. Figure 11 shows the radiation pattern of Sim4. As shown in Figure 10, in the antenna element 1 of this embodiment, even though the dielectric 2 and ground conductor 6 are large relative to the radiation conductor, the frame conductor 5 suppresses the horizontal propagation of the electric field inside the dielectric 2. As a result, as shown in Figure 11, radiation of radio waves in directions oblique to the vertical direction (zenith direction) of the radiation conductor is suppressed, improving the zenith gain. While the zenith gain of a stacked patch antenna without a frame conductor 5 is 5.8 dBi (Sim1), the zenith gain of the antenna element 1 of this embodiment, which has a frame conductor 5, is improved to 8.6 dBi (Sim4).

[0038] When the substrate dimensions are further increased, the effect of the frame conductor becomes even more pronounced. In a stacked patch antenna (Sim3) in which the dimensions of the dielectric 2 and the ground conductor 6 in the XY directions are 15 mm x 15 mm and which does not have a frame conductor 5, radiation in diagonal directions (horizontal directions) relative to the zenith direction increases, and the zenith gain further decreases to 3.8 dBi. In contrast, the zenith gain of the antenna element 1 (Sim5) of this embodiment, which has a frame conductor 5, is improved to 9.3 dBi.

[0039] <Position of Frame-Shaped Conductor: Z Direction> The position of the frame-shaped conductor according to this embodiment will be described using Figure 4. The position of the frame-shaped conductor 5 was changed in the Z direction, and the change in the zenith gain of the antenna element 1 was confirmed by simulation. In Figure 4, the width of the dielectric 2 and the ground conductor 6 was set to 10.0 mm, and the width D of the frame-shaped conductor 5 was set to 1.47 mm (3λ / 4). When the frame-shaped conductor 5 and the second radiation conductor 4 were located on the same plane, the distance E between the frame-shaped conductor 5 and the second radiation conductor 4 was set to 0.49 mm (λ / 4). The other conditions were the same as those described above. The position of the frame-shaped conductor 5 in the Z direction (vertical direction) in simulation model Sim4 was changed.

[0040] The reference position was the position of the second radiation conductor 4 in the Z direction. The position of the frame-shaped conductor 5 was changed only vertically (Z direction) without changing it horizontally (X and Y directions), and the zenith gain of the antenna element 1 was confirmed by simulation.

[0041] 12 is a graph showing the change in the zenith gain of the antenna element when the position of the frame conductor is changed in the vertical direction (Z direction). The horizontal axis of the graph represents the position of the frame conductor 5 in the vertical direction. On the horizontal axis of the graph, "0 μm" means that the position of the frame conductor 5 in the vertical direction is the same as the position of the second radiation conductor 4, i.e., the reference position. On the horizontal axis of the graph, a positive value means that the position of the frame conductor 5 is above the reference position (toward the first radiation conductor 3), and a negative value means that the position of the frame conductor 5 is below the reference position (toward the ground conductor 6).

[0042] On the horizontal axis of the graph, "200 μm" means that the frame-shaped conductor 5 is located on the upper surface of the dielectric 2. In this case, the position of the frame-shaped conductor 5 in the vertical direction is the same as the position of the first radiation conductor 3. On the horizontal axis of the graph, "-240 μm" means that the frame-shaped conductor 5 is located on the lower surface of the dielectric 2. In this case, the frame-shaped conductor 5 overlaps and contacts the ground conductor 6.

[0043] As shown in Figure 12, when the horizontal axis of the graph is 0 μm, the zenith gain of the antenna element 1 is maximum. That is, when the frame-shaped conductor 5 and the second radiation conductor 4 are positioned at the same position in the thickness direction of the antenna element 1, the zenith gain is maximum. In addition, in this case, the frame-shaped conductor 5 may be formed between the same dielectric layers 2a as the second radiation conductor 4. Therefore, as shown in Figures 5 to 7, when providing the frame-shaped conductor 5, it is not necessary to increase the number of dielectric layers 2a, and it is not necessary to prepare dielectric layers 2a of different thicknesses in order to set the position of the frame-shaped conductor 5.

[0044] As described above (Sim1), the zenith gain of the antenna element 1 without the frame-shaped conductor 5 is 5.8 dBi. In the graph of Fig. 12, it can be seen that the zenith gain is greater than 5.8 dBi when the horizontal axis of the graph is in the range of more than -240 μm and less than +200 μm. From this, it can be seen that the zenith gain can be improved if the position of the frame-shaped conductor 5 in the vertical direction is between the first radiation conductor 3 and the ground conductor 6.

[0045] In the antenna element 1 when the frame-shaped conductor 5 is located on the upper surface of the dielectric 2, in addition to reflected radio waves, radiated radio waves are emitted from the frame-shaped conductor 5. Part of the radiated radio waves propagates in the air, and part of the radiated radio waves propagates on the surface of the dielectric 2. Therefore, the reflected radio waves are relatively weak, and it is considered that they are unlikely to sufficiently cancel out the radiated radio waves emitted from the second radiation conductor 4.

[0046] In the antenna element 1 when the frame conductor 5 is located on the underside of the dielectric 2, the frame conductor 5 comes into contact with the ground conductor 6, and the frame conductor 5 functions as part of the ground conductor 6. In other words, the antenna element 1 does not have the frame conductor 5, and the gain is equivalent to that of a stacked patch antenna that does not have the frame conductor 5. In addition, the shape of the ground conductor 6 in the antenna element 1 changes, and the distance between the ground conductor 6 and the first radiation conductor 3 and the second radiation conductor 4 becomes smaller. As a result, the antenna characteristics change between the antenna element 1 and an antenna element when the frame conductor 5 is not in contact with the ground conductor 6.

[0047] <Position of frame-shaped conductor: X and Y directions> A phase shift occurs between the radiated radio wave and the reflected radio wave depending on the distance between the end of the second radiation conductor 4 and the end of the frame-shaped conductor 5. The phase of the reflected radio wave may differ by 90° from the phase of the radiated radio wave. This 90° phase difference causes the radio waves to overlap and cancel each other out.

[0048] The position of the frame conductor according to this embodiment will be described with reference to FIG. 3 . In FIG. 3 , the first radiation conductor 3 and the second radiation conductor 4 have the same shape and size, and their centers coincide in a planar perspective view. The distance between the end of the second radiation conductor 4 and the outer peripheral edge of the frame conductor 5 corresponds to the sum (D+E) of the width D of the frame conductor 5 and the distance E between the inner peripheral edge of the frame conductor 5 and the end of the second radiation conductor 4 in FIG. 3 . A phase shift occurs between the radiated radio wave and the reflected radio wave depending on the width D of the frame conductor 5 and the sum (D+E) of the distance E between the inner peripheral edge of the frame conductor 5 and the end of the second radiation conductor 4. From the viewpoint of radio wave cancellation, the width D of the frame conductor and the sum (D+E) of the distance E between the inner peripheral edge of the frame conductor 5 and the end of the second radiation conductor 4 may be equal to the wavelength (λ) of a signal in the target frequency band.

[0049] When the positions of the frame conductor 5 and the second radiation conductor 4 are different in the Z direction, strictly speaking, it is necessary to take into account the positional relationship between the frame conductor 5 and the second radiation conductor 4 in the Z direction when calculating the distance between the end of the second radiation conductor 4 and the outer peripheral edge of the frame conductor 5. However, an actual antenna element is extremely thin compared to its size, that is, its size in the Z direction is extremely small compared to its sizes in the X and Y directions. Therefore, when calculating the distance between the end of the second radiation conductor 4 and the outer peripheral edge of the frame conductor 5, the influence of the positional relationship in the Z direction is extremely small and can be considered to be negligible.

[0050] In Examples 1 to 3, the width D of the frame-shaped conductor 5 and the distance E between the inner peripheral end of the frame-shaped conductor 5 and the edge of the second radiation conductor 4 were changed, and the zenith gain of the antenna element 1 was confirmed by simulation. In Examples 1 to 3, the positions of the frame-shaped conductor 5 and the second radiation conductor 4 in the Z direction were the same. Other conditions were the same as those described above. That is, Example 1 (Sim6) is the same simulation model as the aforementioned Sim4, and Examples 2 (Sim7) and 3 (Sim8) are simulation models in which the width D of the frame-shaped conductor 5 and the distance E between the inner peripheral end of the frame-shaped conductor 5 and the edge of the second radiation conductor 4 were changed in Sim4. Comparative Example 1 was a large stacked patch antenna that did not have the frame-shaped conductor of the aforementioned Sim1.

[0051] Table I shows the relationship between the width and position of the frame conductor 5 and the zenith gain in the antenna element 1. In the table, "Total (D) + (E)" represents the sum of the width D of the frame conductor 5 and the distance E between the inner edge of the frame conductor 5 and the edge of the second radiation conductor 4. In the table, "λ" represents the wavelength of the signal in the target frequency band.

[0052]

[0053] It can be seen that the antenna element 1 (Examples 1 to 3) in which the sum of the width D of the frame-shaped conductor and the distance E between the inner peripheral edge of the frame-shaped conductor 5 and the edge of the second radiation conductor 4 is the wavelength value (λ) of the signal in the target frequency band has a higher zenith gain than Comparative Example 1. From the viewpoint of further improving the zenith gain, the width D of the frame-shaped conductor 5 may be 0.5 times (λ / 2) or less the wavelength value (λ) of the signal in the target frequency band.

[0054] <Method for manufacturing antenna element> The antenna element 1 of this embodiment may be manufactured by the following method. In the following method, ceramics is used as the dielectric 2, and a copper metallized layer is used as the conductor. However, the various materials are not limited to these.

[0055] The raw material powder of the glass ceramic sintered body is kneaded with an organic solvent and an organic binder to obtain a slurry, which is then formed into a sheet by a forming method such as a doctor blade method or a lip coater method to produce a ceramic green sheet.

[0056] The raw material powder of the glass ceramic sintered body mainly comprises powder of a glass component and a filler component, etc. The glass component may be silicon oxide, boron oxide, etc. The filler component may be aluminum oxide.

[0057] Copper powder is mixed with an organic solvent and an organic binder to obtain a metal paste. The obtained metal paste is printed at predetermined positions on a ceramic green sheet using a method such as screen printing. Prior to printing the metal paste, through holes are formed at predetermined positions on the ceramic green sheet. The metal paste is filled into these through holes to form metal paste columns that serve as through conductors that vertically penetrate dielectric layers such as the power supply conductor 7. The ceramic green sheet on which the metal paste has been printed is fired to form copper metallized conductors.

[0058] The antenna element 1 is formed by stacking ceramic green sheets on which copper metal paste layers and the like are formed, and firing the resulting laminate at a temperature in the range of 900 to 1000°C. The sintered ceramic green sheets become the dielectric layers, and the sintered laminate becomes the dielectric 2. The sintered metal pastes become the conductors. The position of each conductor in the Z direction can be adjusted by adjusting the thickness and number of ceramic green sheets. Furthermore, the position of each conductor in the X and Y directions can be adjusted by adjusting the position where the copper metallization layer is formed on the ceramic green sheets.

[0059] The exposed surface of the metallized layer (such as the first radiation conductor 3) may be further coated with a plating layer of nickel, gold, etc. The plating method may be electrolytic plating or electroless plating.

[0060] <Antenna Module> Fig. 13 is a cross-sectional view of the antenna module of this embodiment. The antenna module 100 of this embodiment includes an antenna element 1 and an integrated circuit 130. The integrated circuit 130 may be bonded to the side of the antenna element 1 opposite to the side on which radio waves are emitted. The integrated circuit 130 may be connected to the antenna substrate 110 that includes the antenna element 1.

[0061] The antenna substrate 110 may have an electrode 112 and internal wiring 111. The antenna substrate 110 has a dielectric layer 2b below the antenna element 1. The dielectric layer 2a of the antenna element 1 and the dielectric layer 2b below the antenna substrate 110 may be made of different materials or the same material. The electrode 112 is located on the underside of the antenna substrate 110 and is connected to an electrode 131 of the integrated circuit 130. The internal wiring 111 includes a via conductor penetrating the dielectric layer 2b and a conductor layer located between the dielectric layers 2b. The internal wiring 111 connects the electrode 112 to the feed conductor 7 of the antenna element 1. Another internal wiring 111 connects another electrode 112 to the ground conductor 6 of the antenna element 1. The antenna substrate 110 may also have an internal ground conductor 113. The internal wiring 111 may be sandwiched between the ground conductor 6 and the internal ground conductor 113 to form a stripline. The antenna element 1 and the integrated circuit 130 are connected by the internal wiring 111, so that at least one of a transmission signal is output and a reception signal is input between the integrated circuit 130 and the antenna element 1. The antenna module 100 may include a filter circuit. The filter circuit extracts a signal of a desired frequency band from the signal on the internal wiring 111.

[0062] The above describes the embodiments of the present disclosure. However, the antenna element, antenna substrate, and antenna module of the present disclosure are not limited to the above embodiments. For example, the planar shapes of the first radiation conductor and the second radiation conductor may be polygonal shapes other than rectangular, or shapes that include curved outlines. Furthermore, one or both of the first radiation conductor and the second radiation conductor may have slits. Furthermore, the dielectric may have a space, such as an air gap, between the ground conductor and the second radiation conductor, or between the second radiation conductor and the first radiation conductor. Other details shown in the embodiments may be modified as appropriate without departing from the spirit of the invention.

[0063] An embodiment of the present disclosure will be described below. In the embodiment, (1) an antenna element includes a dielectric, a first radiation conductor, a second radiation conductor, a frame-shaped conductor, a ground conductor, and a feed conductor, wherein the first radiation conductor, the second radiation conductor, and the ground conductor are positioned in that order in a thickness direction of the dielectric and face each other, the second radiation conductor is connected to the feed conductor, the frame-shaped conductor surrounds the second radiation conductor in a planar perspective view in the thickness direction of the dielectric, and the frame-shaped conductor is positioned between the first radiation conductor and the ground conductor in the thickness direction of the dielectric.

[0064] (2) In the antenna element of (1) above, when viewed from above in a planar perspective in the thickness direction of the dielectric, the sum of the width of the frame-shaped conductor and the distance between the frame-shaped conductor and the second radiation conductor is the same as the wavelength of a signal in the target frequency band.

[0065] (3) In the antenna element of (1) or (2) above, the frame-shaped conductor and the second radiation conductor are positioned at the same position in the thickness direction of the dielectric.

[0066] (4) In the antenna element according to any one of (1) to (3) above, the width of the frame-shaped conductor is equal to or less than 0.5 times the wavelength of a signal in a target frequency band.

[0067] In one embodiment, (5) an antenna module includes the antenna element according to any one of (1) to (4) above, and an integrated circuit.

[0068] The present disclosure can be used as an antenna element and an antenna module.

[0069] DESCRIPTION OF SYMBOLS 1 Antenna element 2 Dielectric 2a Dielectric layer 2b Dielectric layer 3 First radiation conductor 4 Second radiation conductor 5 Frame conductor 6 Ground conductor 7 Feeding conductor A Width of the first radiation conductor and the second radiation conductor B Distance between the centers of the thickness of the ground conductor and the first radiation conductor C Distance between the centers of the thickness of the ground conductor and the second radiation conductor D Width of the frame conductor E Distance between the frame conductor and the second radiation conductor 100 Antenna module 110 Antenna substrate 111 Internal wiring 112 Electrode 113 Internal ground conductor 130 Integrated circuit 131 Electrode

Claims

1. An antenna element comprising a dielectric, a first radiating conductor, a second radiating conductor, a frame-shaped conductor, a ground conductor and a power supply conductor, wherein the first radiating conductor, the second radiating conductor and the ground conductor are positioned in order in the thickness direction of the dielectric and face each other, the second radiating conductor is connected to the power supply conductor, the frame-shaped conductor surrounds the second radiating conductor in a planar perspective view in the thickness direction of the dielectric, and the frame-shaped conductor is positioned between the first radiating conductor and the ground conductor in the thickness direction of the dielectric.

2. The antenna element according to claim 1, wherein, in a planar perspective view in the thickness direction of the dielectric, the sum of the width of the frame-shaped conductor and the distance between the frame-shaped conductor and the second radiation conductor is equal to the wavelength of a signal in the target frequency band.

3. The antenna element according to claim 1 or 2, wherein the frame-shaped conductor and the second radiation conductor are positioned at the same position in the thickness direction of the dielectric material.

4. An antenna element according to any one of claims 1 to 3, wherein the width of the frame-shaped conductor is equal to or less than 0.5 times the value of the wavelength of a signal in the target frequency band.

5. An antenna module comprising an antenna element according to any one of claims 1 to 4 and an integrated circuit.

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