Antenna module

Abstract

The present disclosure proposes an antenna module that enables a broadening of frequency range. An antenna module according to the present disclosure comprises: a first dielectric layer that has a first main surface and a second main surface which is on the opposite side from the first main surface; a first patch that is disposed on the first main surface and that is electrically connected to a power feed port; a ground that is disposed on the second main surface; a second dielectric layer that is disposed on the first main surface with the first patch therebetween, and that has a third main surface which contacts the first patch and a fourth main surface which is on the opposite side from the third main surface; and second patches that are disposed on the fourth main surface of the second dielectric layer. The second patches include a plurality of first parasitic patches which are disposed on the fourth main surface and a plurality of second parasitic patches which are disposed with the plurality of first parasitic patches therebetween. Two first parasitic patches are disposed between two second parasitic patches that are disposed opposite each other. A slit is provided between the two first parasitic patches.

Description

Antenna module

[0001] This disclosure relates to an antenna module. This application claims priority under Japanese Patent Application No. 2025-024632, filed in Japan on 19 February 2025, the contents of which are incorporated herein by reference.

[0002] Patent Document 1 discloses a patch antenna.

[0003] The patch antenna disclosed in Patent Document 1 comprises a parasitic unit, a feeding unit, and a feeding network. The feeding unit is powered by the feeding network. That is, a stripline provided in the feeding network is connected to a feeding patch on the feeding unit via a feeding via hole. With this configuration, the feeding network can supply power to the feeding unit.

[0004] In the patch antenna disclosed in Patent Document 1, a parasitic unit is provided on the feed patch of the feed unit, and the parasitic patch is provided on top of the feed patch. The patch antenna disclosed in Patent Document 1 functions as an antenna by electromagnetically coupling the feed patch and the parasitic patch to excite (drive) the parasitic patch.

[0005] The parasitic unit includes a cross-shaped parasitic patch and a rectangular parasitic patch. The inclusion of this cross-shaped parasitic patch in the parasitic unit improves the roll-off characteristics of the entire antenna.

[0006] U.S. Patent Application Publication No. 2021 / 0057823

[0007] However, the patch antenna disclosed in Patent Document 1 has the problem that the bandwidth is reduced because mutual interference increases between the power supply ports at certain frequencies.

[0008] One aspect of this disclosure has been made in view of this problem. One aspect of this disclosure aims to propose, for example, an antenna module that can achieve broadband.

[0009] An antenna module according to a first aspect of the present disclosure comprises: a first dielectric layer having a first main surface and a second main surface on the side opposite to the side with the first main surface; a first patch disposed on the first main surface and electrically connected to a power supply port; a ground disposed on the second main surface; a second dielectric layer disposed on the first main surface via the first patch and having a third main surface in contact with the first patch and a fourth main surface on the side opposite to the side with the third main surface; and a second patch disposed on the fourth main surface of the second dielectric layer. The second patch includes a plurality of first parasitic patches disposed on the fourth main surface and a plurality of second parasitic patches disposed via the plurality of first parasitic patches, wherein two of the first parasitic patches are disposed between two of the second parasitic patches that are facing each other, and a slit is provided between the two of the first parasitic patches.

[0010] This is a schematic perspective view illustrating a patch antenna of the first embodiment of the present disclosure. This is a schematic diagram illustrating an example of the laminated structure of the patch antenna shown in Figure 1. This is a schematic top view illustrating the patch antenna shown in Figure 1. This is a schematic diagram illustrating the first main surface of the first dielectric layer of the patch antenna shown in Figure 1. This is a schematic top view illustrating a patch antenna according to a first comparative example. S parameters of the patch antenna according to the first embodiment of the present disclosure １１ and S parameter S １２ Simulation results of the frequency characteristics and the S-parameters of the patch antenna related to the first comparative example. １１ and S parameter S １２It is a graph showing the simulation results of the frequency characteristics. It is a graph showing the relationship between the gain value and the frequency characteristics of the patch antenna according to the first embodiment of the present disclosure, and the simulation results showing the relationship between the gain value and the frequency characteristics of the patch antenna according to the first comparative example. It is a diagram showing the simulation results of the electric field distribution on the upper surface when the Y-polarized wave is excited in the patch antenna according to the first embodiment of the present disclosure. It is a diagram showing the simulation results of the electric field distribution on the upper surface when the Y-polarized wave is excited in the patch antenna according to the first embodiment of the present disclosure. It is a diagram showing the simulation results of the electric field distribution on the upper surface when the Y-polarized wave is excited in the patch antenna according to the first embodiment of the present disclosure. It is a diagram showing the simulation results of the electric field distribution on the upper surface when the Y-polarized wave is excited in the patch antenna according to the first comparative example. It is a diagram showing the simulation results of the electric field distribution on the upper surface when the Y-polarized wave is excited in the patch antenna according to the first comparative example. It is a diagram showing the simulation results of the electric field distribution on the upper surface when the Y-polarized wave is excited in the patch antenna according to the first comparative example. It is a top view schematically showing the patch antenna according to the embodiment of the present disclosure. The S parameter S of the patch antenna according to the embodiment of the present disclosure １１ and the S parameter S １２ It is a graph showing the simulation results of the frequency characteristics. The S parameter S of the patch antenna according to the embodiment of the present disclosure １１ and the S parameter S １２ It is a graph showing the simulation results of the frequency characteristics. The S parameter S of the patch antenna according to the embodiment of the present disclosure １１ and the S parameter S １２ It is a graph showing the simulation results of the frequency characteristics. The S parameter S of the patch antenna according to the embodiment of the present disclosure １１ and the S parameter S １２This is a graph showing the simulation results of the frequency characteristics. This is a schematic perspective view showing the configuration of a patch antenna according to the second embodiment of this disclosure. This is a schematic top view illustrating the patch antenna shown in Figure 19. This is a schematic top view illustrating a patch antenna according to the second comparative example. S parameters of the patch antenna according to the second embodiment １１ Simulation results of the frequency characteristics and the S-parameters of the patch antenna related to the second comparative example. １１ This graph shows the simulation results of the frequency characteristics. This graph shows the relationship between the gain value and frequency characteristics of the patch antenna according to the second embodiment, and the relationship between the gain value and frequency characteristics of the patch antenna according to the second comparative example.

[0011] The embodiments of this disclosure will be described below with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0012] 1. First Embodiment 1.1 Patch Antenna Figure 1 is a schematic perspective view illustrating a patch antenna 1 according to the first embodiment of the present disclosure. Figure 2 is a schematic diagram illustrating an example of the laminated structure of the patch antenna 1 shown in Figure 1. Figure 3 is a schematic top view illustrating the patch antenna 1 shown in Figure 1. Figure 4 is a schematic diagram illustrating the first main surface 11a of the first dielectric layer 11 provided in the patch antenna 1 shown in Figure 1. In Figures 1 and 3, members provided below the fourth main surface 14b are indicated by dashed lines.

[0013] The patch antenna 1 (antenna module) according to the first embodiment transmits radio waves corresponding to an input signal and outputs a signal corresponding to a received radio wave. The patch antenna 1 is incorporated into a communication module. The patch antenna 1 may also be incorporated into equipment other than a communication module. The patch antenna 1 can provide a small and thin antenna when the frequency of the radio waves to be transmitted and received is high.

[0014] As shown in FIGS. 1 to 4, the patch antenna 1 includes a first dielectric layer 11, a first patch 12, a ground 13, a second dielectric layer 14, a second patch 15, a first via 16, and a second via 17. In the patch antenna 1 according to the first embodiment, the second patch 15 includes a plurality of L-shaped parasitic patches 21 (first parasitic patches) and a plurality of rectangular parasitic patches 22 (second parasitic patches).

[0015] The first dielectric layer 11 has a first main surface 11a and a second main surface 11b. The first main surface 11a and the second main surface 11b are on opposite sides of each other. The first main surface 11a and the second main surface 11b extend in the X direction DX and the Y direction DY. The X direction DX and the Y direction DY are perpendicular to each other.

[0016] The first patch 12 is disposed on the first main surface 11a. The first patch 12 has a film-like shape and serves as a patch surface. The first patch 12 has a square shape in plan view. Therefore, as shown in FIG. 4, the first patch 12 has a pair of first sides 12a and a pair of second sides 12b in plan view. The pair of first sides 12a face each other, are parallel to each other, are separated from each other in the X direction DX, and extend in the Y direction DY. The pair of second sides 12b face each other, are parallel to each other, are separated from each other in the Y direction DY, and extend in the X direction DX. The first side 12a and the second side 12b are perpendicular to each other. The first patch 12 is made of a conductor such as metal.

[0017] The second dielectric layer 14 is disposed on the first main surface 11a of the first dielectric layer 11 via the first patch 12. The second dielectric layer 14 has a third main surface 14a and a fourth main surface 14b. The third main surface 14a is in contact with the first patch 12. The third main surface 14a and the fourth main surface 14b are on opposite sides of each other. The third main surface 14a and the fourth main surface 14b extend in the X direction DX and the Y direction DY. The X direction DX and the Y direction DY are perpendicular to each other.

[0018] The second patch 15 is disposed on the fourth main surface 14b. The second patch 15 includes a plurality of L-shaped parasitic patches 21 (first parasitic patches) and a plurality of rectangular parasitic patches 22 (second parasitic patches). In the present embodiment, the second patch 15 includes four L-shaped parasitic patches 21 (first L-shaped parasitic patch 21a, second L-shaped parasitic patch 21b, third L-shaped parasitic patch 21c, and fourth L-shaped parasitic patch 21d). The second patch 15 also includes four rectangular parasitic patches 22 (first rectangular parasitic patch 22a, second rectangular parasitic patch 22b, third rectangular parasitic patch 22c, and fourth rectangular parasitic patch 22d).

[0019] Each of the four rectangular parasitic patches 22 is disposed on the fourth main surface 14b via the four L-shaped parasitic patches 21. More specifically, each of the four rectangular parasitic patches 22 is disposed in four regions partitioned by each of the four L-shaped parasitic patches 21 on the fourth main surface 14b. Each of the four rectangular parasitic patches 22 is disposed along the direction of radio waves (X-polarized wave or Y-polarized wave) that can be transmitted and received by the patch antenna 1.

[0020] In order to ensure the port-to-port isolation of the patch antenna 1, in a plan view, the area of the L-shaped parasitic patch 21 is smaller than that of the rectangular parasitic patch 22.

[0021] The L-shaped parasitic patch 21 has a membrane-like shape and forms a patch surface. The first L-shaped parasitic patch 21a has an L-shape in a plan view, as shown in Figure 3, which includes a first leg portion 21a1 that extends in the X direction DX (the first part of the first parasitic patch) and a second leg portion 21a2 that extends in the Y direction DY (the second part of the first parasitic patch). The second L-shaped parasitic patch 21b has an L-shape which includes a third leg portion 21b1 that extends in the X direction DX and a fourth leg portion 21b2 that extends in the Y direction DY. The third L-shaped parasitic patch 21c has an L-shape which includes a fifth leg portion 21c1 that extends in the X direction DX and a sixth leg portion 21c2 that extends in the Y direction DY. The fourth L-shaped parasitic patch 21d has an L-shape including a seventh leg portion 21d1 which is a surface extending in the X direction DX and an eighth leg portion 21d2 which is a surface extending in the Y direction DY. As shown in Figure 3, the L-shaped parasitic patch 21 is positioned along the edge extending in the X direction DX and the edge extending in the Y direction DY of the nearest rectangular parasitic patch 22.

[0022] In a plan view, the dimensions in the X-direction DX of the first leg portion 21a1 and the third leg portion 21b1, which extend to one side along the X-direction DX from the center point O1 of the cross slit 21s, and the dimensions in the X-direction DX of the fifth leg portion 21c1 and the seventh leg portion 21d1, which extend to the other side along the X-direction DX from the center point O1 of the cross slit 21s, are equal.

[0023] Furthermore, in a plan view, the dimensions in the Y-direction DY of the second leg portion 21a2 and the sixth leg portion 21c2, which extend to one side along the Y-direction DY from the center point O1 of the cross slit 21s, and the dimensions in the Y-direction DY of the fourth leg portion 21b2 and the eighth leg portion 21d2, which extend to the other side along the Y-direction DY from the center point O1 of the cross slit 21s, are equal. Note that the ratio of the first leg portion 21a1 to the second leg portion 21a2, the third leg portion 21b1 to the fourth leg portion 21b2, the fifth leg portion 21c1 to the sixth leg portion 21c2, and the seventh leg portion 21d1 to the eighth leg portion 21d2 do not necessarily have to be 1:1. Therefore, the ratio of the leg portion, which is the surface extending in the X-direction DX, to the leg portion 21, which is the surface extending in the Y-direction DY, does not necessarily have to be 1:1.

[0024] Furthermore, in a plan view, the center point O1 of the cross slit 21s coincides with the center point O2 of the first patch 12.

[0025] Furthermore, as shown in Figure 3, a second slit, which is part of the cross slit 21s, is formed between two L-shaped parasitic patches 21 arranged side by side in the Y direction DY, extending in the X direction DX. Also, a first slit, which is part of the cross slit 21s, is formed between two L-shaped parasitic patches 21 arranged side by side in the X direction DX, extending in the Y direction DY. In other words, the first slit of the cross slit 21s is provided to extend in a direction perpendicular to the direction connecting the center point O2 of the first patch 12 and the first power supply point 51 to which current is supplied from the first power supply port P1, in a plan view. Furthermore, the second slit of the cross slit 21s is provided to extend in a direction perpendicular to the direction connecting the center point O2 of the first patch 12 and the second power supply point 52 to which current is supplied from the second power supply port P2, in a plan view.

[0026] Here, the slit dimension corresponding to the first leg portion 21a1 or the third leg portion 21b1 is defined as the X-direction slit dimension X_SLT. The slit dimension corresponding to the fifth leg portion 21c1 or the seventh leg portion 21d1 is also defined as X_SLT. Furthermore, the slit dimension corresponding to the fourth leg portion 21b2 or the eighth leg portion 21d2 is defined as the Y-direction slit dimension Y_SLT. The slit dimension corresponding to the second leg portion 21a2 or the sixth leg portion 21c2 is also defined as Y_SLT.

[0027] As shown in Figure 3, the X-direction slit dimension X_SLT of the cross slit 21s (second slit) extending in the X-direction DX corresponds to the X-direction dimension of the first leg portion 21a1 or the third leg portion 21b1.

[0028] Furthermore, the Y-direction slit dimension Y_SLT of the cross slit 21s (first slit) extending in the Y-direction DY corresponds to the Y-direction dimension of the fourth leg portion 21b2 or the eighth leg portion 21d2.

[0029] Furthermore, the width dimension of the cross slit 21s is denoted as the slit width dimension W_SLT. The width dimension of the cross slit 21s is assumed to be equal throughout. The width dimension of the L-shaped parasitic patch 21 is denoted as the parasitic patch width dimension L_CX. The width dimension of the L-shaped parasitic patch 21 is assumed to be equal throughout.

[0030] Furthermore, the dimension between the rectangular parasitic patch 22 and the L-shaped parasitic patch 21 is defined as the gap dimension G. The dimensions between the first rectangular parasitic patch 22a and the first L-shaped parasitic patch 21a, the dimensions between the second rectangular parasitic patch 22b and the second L-shaped parasitic patch 21b, the dimensions between the third rectangular parasitic patch 22c and the third L-shaped parasitic patch 21c, and the dimensions between the fourth rectangular parasitic patch 22d and the fourth L-shaped parasitic patch 21d may all be equal. For example, when considering the first rectangular parasitic patch 22a, it is sufficient that the dimension between the first rectangular parasitic patch 22a and the first L-shaped parasitic patch 21a is equal to either the dimension between the second rectangular parasitic patch 22b and the second L-shaped parasitic patch 21b, or the dimension between the third rectangular parasitic patch 22c and the third L-shaped parasitic patch 21c.

[0031] By forming a cross-shaped slit 21s between the L-shaped parasitic patches 21, the bandwidth of radio waves that can be transmitted and received by the patch antenna 1 can be widened. Details regarding the relationship between this cross-shaped slit 21s and the bandwidth will be described later.

[0032] The first rectangular parasitic patch 22a to the fourth rectangular parasitic patch 22d each have a membrane-like shape and form a patch surface. In plan view, each of the first rectangular parasitic patch 22a to the fourth rectangular parasitic patch 22d has a square shape. The side dimension L_CP of each of the first rectangular parasitic patch 22a, second rectangular parasitic patch 22b, third rectangular parasitic patch 22c, and fourth rectangular parasitic patch 22d is denoted as the rectangular parasitic patch side dimension L_CP.

[0033] Each of the first to fourth rectangular parasitic patches 22a to 22d is positioned at one of the four corners of the fourth main surface 14b. The first rectangular parasitic patch 22a and the second rectangular parasitic patch 22b are positioned along the Y direction DY via the first leg 21a1 of the first L-shaped parasitic patch 21a and the third leg 21b1 of the second L-shaped parasitic patch 21b. The third rectangular parasitic patch 22c and the fourth rectangular parasitic patch 22d are positioned via the fifth leg 21c1 of the third L-shaped parasitic patch 21c and the seventh leg 21d1 of the fourth L-shaped parasitic patch 21d.

[0034] The first rectangular parasitic patch 22a and the third rectangular parasitic patch 22c are arranged along the X direction DX via the second leg portion 21a2 of the first L-shaped parasitic patch 21a and the sixth leg portion 21c2 of the third L-shaped parasitic patch 21c. The second rectangular parasitic patch 22b and the fourth rectangular parasitic patch 22d are arranged via the fourth leg portion 21b2 of the second L-shaped parasitic patch 21b and the eighth leg portion 21d2 of the fourth L-shaped parasitic patch 21d.

[0035] The ground 13 is placed on the second main surface 11b of the first dielectric layer 11. The ground 13 has a film-like shape and forms the ground surface. The first patch 12 faces the ground 13 across the first dielectric layer 11. As a result, the first patch 12 is electromagnetically coupled with the ground 13, forming an antenna. The ground 13 is made of a conductor such as a metal.

[0036] Here, as shown in Figure 4, the center line of the first patch 12 in the Y direction DY is referred to as the first center line C1, and the center line of the first patch 12 in the X direction DX is referred to as the second center line C2. Furthermore, the center point of the first patch 12 where the first center line C1 and the second center line C2 intersect is referred to as the center point O2.

[0037] The first via 16 has a linear shape. In a plan view, the first via 16 is positioned on the first centerline C1. The first via 16 is a coaxial line positioned to penetrate the first dielectric layer 11 from the ground 13 toward the first main surface 11a. The coaxial line is made of a conductor such as metal. In other words, the first via 16 extends from the back side of the patch antenna 1, i.e., the ground 13 side, in the thickness direction of the first dielectric layer 11, and one end of the first via 16 reaches the first main surface 11a. The other end of the first via 16 is on the second main surface 11b, and a signal can be input between the other end of the first via 16 and the ground 13. A signal can also be output from between the other end of the first via 16 and the ground 13. As a result, the other end of the first via 16 and the ground 13 can be used as the first power supply port P1. Furthermore, one end of the first via 16 can be designated as the first power supply point 51 in the first patch 12.

[0038] The distance DX in the X direction from the second centerline C2 to the first feed point 51 affects the feed point impedance of the first feed point 51. This distance DX in the X direction is set so that the feed point impedance of the first feed point 51 is equal to the port impedance. The port impedance is usually 50Ω.

[0039] The second via 17 has a linear shape. In a plan view, the second via 17 is positioned on the second centerline C2. The second via 17 is a coaxial line positioned to penetrate the first dielectric layer 11 from the ground 13 toward the first main surface 11a. The coaxial line is made of a conductor such as metal. In other words, the second via 17 extends from the back side of the patch antenna 1, i.e., the ground 13 side, in the thickness direction of the first dielectric layer 11, and one end of the second via 17 reaches the first main surface 11a. The other end of the second via 17 is on the second main surface 11b, and a signal can be input between the other end of the second via 17 and the ground 13. A signal can also be output from between the other end of the second via 17 and the ground 13. As a result, the other end of the second via 17 and the ground 13 can be used as a second feed port P2. In addition, one end of the second via 17 can be used as the second feed point 52 in the first patch 12. The Y-direction DY distance from the first centerline C1 to the second feed point 52 affects the feed point impedance of the second feed point 52. This Y-direction DY distance is set so that the feed point impedance of the second feed point 52 is equal to the port impedance. The port impedance is typically 50Ω.

[0040] As described above, patch antenna 1 is a patch antenna equipped with two dielectric layers, a first dielectric layer 11 and a second dielectric layer 14. Because there are two resonance points due to electromagnetic field coupling in the first dielectric layer 11 and the second dielectric layer 14, the frequency bandwidth can be widened compared to a patch antenna equipped with only the first dielectric layer 11.

[0041] Furthermore, the patch antenna 1 includes four rectangular parasitic patches 22 and four L-shaped parasitic patches 21 on the fourth main surface 14b of the second dielectric layer 14.

[0042] For example, in order for patch antenna 1 to function as an antenna capable of transmitting and receiving X-polarized and Y-polarized waves, patch antenna 1 needs to have four rectangular parasitic patches 22. Furthermore, in order to improve the overall roll-off characteristics of the antenna, patch antenna 1 also has four L-shaped parasitic patches 21. However, if cross-shaped parasitic patches are laid flat on the fourth main surface 14b instead of the four L-shaped parasitic patches 21, the frequency bandwidth of the antenna will be reduced. Therefore, cross-shaped slits 21s are provided between adjacent L-shaped parasitic patches 21. By electromagnetic field coupling between the L-shaped parasitic patches 21 with the cross-shaped slits 21s in between, the electric field direction can be aligned to the X direction DX or the Y direction DY, thereby improving isolation. As a result, the frequency bandwidth of radio waves that can be transmitted and received by patch antenna 1 can be improved.

[0043] 1.2 When a signal is input to the first power supply port P1 for X-polarization and Y-polarization transmission and reception, a first current J1 as shown in Figure 4 flows through the first patch 12. The direction in which the first current J1 flows is aligned with the X direction DX in a plan view. At this time, the second side 12b of the first patch 12 resonates at a frequency that matches an integer multiple of half a wavelength. For example, if the length of the second side 12b is half a wavelength, a current standing wave is generated with zero amplitude at both ends of the second side 12b of the first patch 12 and maximum amplitude in the center. Since the phase difference between the current standing wave and the voltage standing wave is 1 / 4 wavelength, the voltage distribution is maximum at both ends of the second side 12b of the first patch 12 and zero in the center. Also, the electric field strength and voltage amplitude generated between the first patch 12 and the ground 13 are proportional. For this reason, the electric field strength is maximum at both ends of the second side 12b of the first patch 12 and zero in the center. This generates radiation originating from an electric field excited near the end of the first side 12a, which corresponds to the end of the second side 12b.

[0044] Furthermore, a second patch 15 is provided on the first patch 12 via a second dielectric layer 14. When a first current J1 flows through the first patch 12, the rectangular parasitic patch 22 of the first patch 12 and the second patch 15 are electromagnetically coupled, and radio waves are emitted from the resonant rectangular parasitic patch 22. The direction of the electric field of the emitted radio waves (the direction of the electric field lines) aligns with the X direction DX in a plan view. Therefore, the emitted radio waves are X-polarized.

[0045] When a signal is input to the second power supply port P2, a second current J2, as shown in Figure 4, flows through the first patch 12. The direction of the second current J2 is aligned with the Y direction DY in a plan view. At this time, the first side 12a of the first patch 12 resonates at a frequency that matches an integer multiple of half a wavelength. For example, if the length of the first side 12a is half a wavelength, a current standing wave is generated with zero amplitude at both ends of the first side 12a of the first patch 12 and maximum amplitude in the center. Since the phase difference between the current standing wave and the voltage standing wave is only 1 / 4 wavelength, the voltage distribution is maximum at both ends of the first side 12a of the first patch 12 and zero in the center. Also, the electric field strength and voltage amplitude generated between the first patch 12 and the ground 13 are proportional. Therefore, the electric field strength is maximum at both ends of the first side 12a of the first patch 12 and zero in the center. This generates radiation originating from an electric field excited near the second side 12b, which corresponds to the end of the first side 12a.

[0046] Furthermore, a second patch 15 is provided on the first patch 12 via a second dielectric layer 14. When a second current J2 flows through the first patch 12, the rectangular parasitic patch 22 of the first patch 12 and the second patch 15 are electromagnetically coupled, and radio waves are emitted from the resonant rectangular parasitic patch 22. The direction of the electric field of the emitted radio waves (the direction of the electric field lines) aligns with the Y direction DY in a plan view. Therefore, the transmitted radio waves are Y-polarized.

[0047] Furthermore, when patch antenna 1 receives X-polarization, a first current J1, as shown in Figure 4, flows in the first patch 12, which is electromagnetically coupled with the second patch 15. At this time, an electric field is applied to the first feed point 51, and a signal is output from the first feed port P1, but no signal is output from the second feed port P2.

[0048] When patch antenna 1 receives a Y-polarized wave, a second current J2, as shown in Figure 4, flows in the first patch 12, which is electromagnetically coupled to the second patch 15. At this time, an electric field is applied to the second feed point 52, and a signal is output from the second feed port P2, but no signal is output from the first feed port P1.

[0049] 1.3 S-parameters of a two-port circuit having a first power supply port P1 and a second power supply port P2 １１ and S ２２ This corresponds to reflectance. The first power supply port P1 and the second power supply port P2 differ only in the polarization they handle, S １１ and S ２２ They have the same value. Therefore, below, S １１ Only the S-parameters of patch antenna 1 are discussed. １１ A small value indicates high radiation efficiency of patch antenna 1. The frequency band that can be used for communication is roughly determined by the S-parameter S of patch antenna 1. １１ This is the frequency band where the noise level is below -10 dB.

[0050] S-parameters S in a two-port circuit equipped with a first power supply port P1 and a second power supply port P2 ２１ and S １２ This corresponds to transmittance. The first power supply port P1 and the second power supply port P2 differ only in the polarization they handle, S ２１ and S １２ They have the same value. Therefore, below, S １２ Only the S-parameters of patch antenna 1 are discussed. １２ A small value indicates high port-to-port isolation of patch antenna 1. Desired S-parameters of patch antenna 1 １２ The level is -10 dB or lower.

[0051] 1.4 Configuration of the First Comparative Example In order to evaluate the performance of the patch antenna 1 according to the first embodiment of this disclosure, the first comparative example shown in Figure 5 is used. Figure 5 is a schematic top view illustrating the patch antenna 200 according to the first comparative example.

[0052] The patch antenna 200 according to the first comparative example differs from the patch antenna 1 according to the first embodiment only in that it has one cross-shaped parasitic patch 221 instead of four L-shaped parasitic patches 21, and that it does not have a cross-shaped slit 21s. For all other points, the patch antenna 200 according to the first comparative example has the same configuration as the patch antenna 1 according to the first embodiment, so a detailed explanation is omitted. Specifically, in the patch antenna 200 according to the first comparative example, a second patch 215 is arranged on the upper surface of the second dielectric layer 214. The second patch 215 includes a cross-shaped parasitic patch 221 and four rectangular parasitic patches 222.

[0053] The cruciate parasitic patch 221 has a membrane-like shape and forms a patch surface. In a plan view, as shown in Figure 5, the cruciate parasitic patch 221 has a cross shape in which a surface extending in the X direction DX and a surface extending in the Y direction DY intersect perpendicularly.

[0054] 1.5 Influence of the cross slit between L-shaped parasitic patches Figure 6 shows the S-parameter S of the patch antenna 1 according to the first embodiment of this disclosure. １１ and S parameter S １２ Simulation results of the frequency characteristics and the S-parameters of the patch antenna 200 related to the first comparative example. １１ and S parameter S １２ Figure 7 is a graph showing the simulation results of the frequency characteristics of the patch antenna 1 according to the first embodiment of this disclosure and the relationship between the gain value and the frequency characteristics of the patch antenna 200 according to the first comparative example. The gain is a measured value that indicates the antenna's ability to radiate radio waves in any direction compared to an ideal isotropic radiator.

[0055] In patch antenna 1, it is preferable that the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT shown in Figure 3 are in the range of 0.3 mm or more and 0.6 mm or less. In particular, it is preferable that the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT are 0.5 mm.

[0056] Furthermore, in patch antenna 1, it is preferable that the rectangular parasitic patch side dimension L_CP is 0.3 mm or more and 0.7 mm or less. In particular, it is preferable that the rectangular parasitic patch side dimension L_CP is 0.6 mm.

[0057] Furthermore, in patch antenna 1, it is preferable that the parasitic patch width dimension L_CX is in the range of 0.1 mm or more and 0.25 mm or less.

[0058] Figures 6 and 7 show the simulation results when the slit width dimension W_SLT of patch antenna 1 is 0.05 mm, the gap dimension G is 0.05 mm, the slit dimension X_SLT in the X direction and the slit dimension Y_SLT in the Y direction are both 0.5 mm, the rectangular parasitic patch side dimension L_CP is 0.6 mm, and the parasitic patch width dimension L_CX is 0.125 mm. Therefore, the total dimension of the slit extending in the X direction DX is X_SLT × 2, which is 1.0 mm. The total dimension of the slit extending in the Y direction DY is Y_SLT × 2, which is 1.0 mm.

[0059] Furthermore, Figure 5 shows the simulation results for the first comparative example, where the rectangular parasitic patch side dimension L_CP of the patch antenna 200 is 0.6 mm, the gap dimension G is 0.05 mm, the dimensions of the first and second legs of the cross-shaped parasitic patch 221, in other words, the dimensions corresponding to the X-direction slit dimension X_SLT of the patch antenna 1, are 0.5 mm, the dimensions of the third and fourth legs, in other words, the dimensions corresponding to the Y-direction slit dimension Y_SLT of the patch antenna 1, are 0.5 mm, and the parasitic patch width dimension L_CX of the cross-shaped parasitic patch 221 is 0.25 mm.

[0060] As shown in Figure 6, the S-parameter S of the patch antenna 1 １１ When the value of is -10 dB or less, the bandwidth of the frequency response is the S parameter S of the patch antenna 200 according to the first comparative example. １１ The value of this becomes larger than the bandwidth of the frequency response where it is -10 dB or less.

[0061] Also, the S-parameter S of patch antenna 1 １２When the value of is -10 dB or less, the bandwidth of the frequency response is the S parameter S of the patch antenna 200 according to the first comparative example. １２ For example, the value of becomes larger than the bandwidth of the frequency response when it is -10 dB or less.

[0062] Furthermore, as shown in Figure 7, for example, when the antenna gain value is 5 dB or more, the bandwidth of the frequency characteristics of patch antenna 1 is larger than the bandwidth of the frequency characteristics of patch antenna 200 according to the first comparative example.

[0063] From the above, it can be seen that by forming a cross-shaped slit 21s between the four L-shaped parasitic patches 21, as in patch antenna 1, the bandwidth of radio waves that can be transmitted and received in patch antenna 1 can be widened.

[0064] 1.6 Electric Field Distribution on the Upper Surface of the Patch Antenna Figures 8 to 10 show the simulation results of the electric field distribution on the upper surface when Y polarization is excited in the patch antenna 1 according to the first embodiment of this disclosure. The dimensions of each part of the patch antenna 1 used in this simulation are the same as the dimensions of each part of the patch antenna 1 used when obtaining the simulation results shown in Figures 6 and 7.

[0065] Figure 8 shows the simulation results of the Y-polarized electric field distribution when patch antenna 1 radiates 50 GHz radio waves, Figure 9 shows the simulation results of the Y-polarized electric field distribution when patch antenna 1 radiates 60 GHz radio waves, and Figure 10 shows the simulation results of the Y-polarized electric field distribution when patch antenna 1 radiates 70 GHz radio waves.

[0066] As shown in Figures 8 and 9, in the region (A) where the cross slit 21s is provided, the electric field direction is parallel to the Y direction DY in all cases of 50 GHz, 60 GHz, and 70 GHz.

[0067] Figures 11 to 13 show the simulation results of the electric field distribution on the upper surface when Y polarization is excited in the patch antenna 200 according to the first comparative example. The region (A) shown in Figures 11 to 13 is the same as the region (A) shown in Figures 8 to 9. The dimensions of each part of the patch antenna 200 according to the first comparative example used in this simulation are the same as the dimensions of each part of the patch antenna 200 used when obtaining the simulation results shown in Figures 6 and 7.

[0068] Figure 11 shows the simulation results of the Y-polarized electric field distribution when the patch antenna 200 radiates 50 GHz radio waves, Figure 12 shows the simulation results of the Y-polarized electric field distribution when the patch antenna 200 radiates 60 GHz radio waves, and Figure 13 shows the simulation results of the Y-polarized electric field distribution when the patch antenna 200 radiates 70 GHz radio waves.

[0069] As shown in Figures 11 and 12, at 50 GHz and 60 GHz, the electric field direction in the region (A) of the cross-shaped parasitic patch 221 is parallel to the Y direction DY. Therefore, when the radiated radio waves are 50 GHz and 60 GHz, the patch antenna 200 can ensure the directionality of the radiated radio waves and port isolation in the same way as the patch antenna 1. However, at 70 GHz, the electric field direction becomes disordered in the region (A) of the cross-shaped parasitic patch 221.

[0070] As shown above, the simulation results in Figures 8 to 13 indicate that the patch antenna 1 can improve the directionality of radiated radio waves and port isolation in all cases of 50 GHz, 60 GHz, and 70 GHz. Therefore, by forming a cross-shaped slit 21s between the four L-shaped parasitic patches 21, the bandwidth of radio waves that can be transmitted and received by the patch antenna 1 can be widened.

[0071] 1.7 Relationship between the difference in slit length in two polarization directions and the bandwidth of the patch antenna Figure 14 is a schematic top view illustrating a patch antenna according to an embodiment of the present disclosure. In the patch antenna according to the embodiment shown in Figure 14, the patch antenna 1 is configured such that the length of the leg portion of the L-shaped parasitic patch 21 extending in the Y direction DY is shortened. The dimensions of each part of the patch antenna 1 according to the embodiment are the same as the dimensions of each part of the patch antenna 1 used when obtaining the simulation results shown in Figures 6 and 7.

[0072] In other words, in the patch antenna according to the embodiment, the dimensions of the second leg portion 21a2 and the sixth leg portion 21c2 in the Y direction DY are configured to be shorter than those of the patch antenna 1 according to the first embodiment. Also, the dimensions of the fourth leg portion 21b2 and the eighth leg portion 21d2 in the Y direction DY are configured to be shorter than those of the patch antenna 1 according to the first embodiment. Therefore, in the patch antenna according to the embodiment, the dimensions of the portion of the cross slit 21s extending along the Y direction DY (first slit) are configured to be shorter than those of the patch antenna 1 according to the embodiment.

[0073] As shown in Figure 14, we define |Y_SLT - X_SLT| = D. Then, the patch antenna when D = 0.0001 mm is designated as Example 1. The patch antenna when D = 0.1 mm is designated as Example 2. The patch antenna when D = 0.2 mm is designated as Example 3. The patch antenna when D = 0.3 mm is designated as Example 4.

[0074] For each of Examples 1 to 4, the S parameter S is -10 dB or less, as shown in Figures 15 to 18. １１ Frequency bandwidth and S-parameters １１ The frequency bandwidth was investigated. The S-parameter S １１ The frequency bandwidth is less than -10 dB, according to the S-parameter S. １１ It is calculated as the difference between the upper and lower frequency limits. S-parameters ２２ The frequency bandwidth is less than -10 dB, according to the S-parameter S. ２２It is calculated as the difference between the upper and lower frequency limits. Figures 15 to 18 show the S-parameters of a patch antenna according to an embodiment of the present disclosure. １１ and S parameter S １２ These are graphs showing the simulation results of the frequency characteristics. Specifically, Figure 15 is a graph showing the simulation results of Example 1 where D = 0.0001 mm. Figure 16 is a graph showing the simulation results of Example 2 where D = 0.1 mm. Figure 17 is a graph showing the simulation results of Example 3 where D = 0.2 mm. Figure 18 is a graph showing the simulation results of Example 4 where D = 0.3 mm.

[0075] Here, for Examples 1 to 4, the S parameter S １１ Frequency bandwidth and S-parameters ２２ The difference between this and the frequency bandwidth is obtained from the values ​​shown in Table 1.

[0076] As shown in Table 1, the difference (D) between the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT, and the S parameter S １１ Frequency bandwidth and S-parameters ２２ A correlation is observed between the difference with the frequency bandwidth. That is, in Examples 1 and 2, where the difference (D) between the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT is 0.1 mm or less, the S parameter S １１ Frequency bandwidth and S-parameters ２２ The frequency bandwidth is approximately the same value. Also, the S parameter S is different between Example 1 and Example 2. １１ A graph of the frequency response and the S-parameters S ２２ The graph of the frequency response is almost identical in shape to the graph of the other device. Therefore, the difference between the two is considered to be within an acceptable range.

[0077] On the other hand, from the results of Examples 3 and 4, when the difference (D) between the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT is 0.2 mm or more, the S parameter S １１ Frequency bandwidth and S-parameters ２２ The difference with respect to the frequency bandwidth tends to become larger.

[0078] Therefore, it is preferable that the patch antenna 1 is configured such that the difference (D) between the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT is 0.1 mm or less. When the patch antenna 1 is configured in this way, such that the difference (D) between the X-direction slit dimension X_SLT and the Y-direction slit dimension Y_SLT is 0.1 mm or less, both X-polarized and Y-polarized radio waves can be transmitted and received with similar bandwidths.

[0079] 2. In the second and subsequent embodiments, the differences between the second embodiment and the first embodiment will be explained. For aspects not explained, the same configuration as that used in the first embodiment will be used in the second embodiment.

[0080] 2.1 Patch Antenna According to the Second Embodiment Figure 19 is a schematic perspective view showing the configuration of the patch antenna 100 according to the second embodiment of this disclosure. Figure 20 is a schematic top view illustrating the patch antenna 100 shown in Figure 19.

[0081] In the patch antenna 1 according to the first embodiment, as shown in Figure 1, a first via 16 and a second via 17 are provided.

[0082] In contrast, the patch antenna 100 according to the second embodiment is equipped only with the first via 16, as shown in Figure 19. That is, it is a patch antenna capable of transmitting and receiving only X-polarized waves.

[0083] Furthermore, as shown in Figure 3, the patch antenna 1 according to the first embodiment includes a second patch 15 on the fourth main surface 14b of the second dielectric layer 14, which includes four L-shaped parasitic patches 21 and four rectangular parasitic patches 22.

[0084] In contrast, the patch antenna 100 according to the second embodiment includes a second patch 115 comprising two rod-shaped parasitic patches 121 and two rectangular parasitic patches 122 extending in the Y direction DY, as shown in Figures 19 and 20.

[0085] With respect to the points below, the patch antenna 1 according to the first embodiment and the patch antenna 100 according to the second embodiment have similar configurations, so the same reference numerals are used for similar components and their descriptions are omitted.

[0086] As shown in Figure 20, in the patch antenna 100 according to the second embodiment, two rod-shaped parasitic patches 121 (first rod-shaped parasitic patch 121a and second rod-shaped parasitic patch 121b) are arranged on the fourth main surface 14b of the second dielectric layer 14, sandwiched between two rectangular parasitic patches 122 (first rectangular parasitic patch 122a and second rectangular parasitic patch 122b). A slit 121s is provided between the first rod-shaped parasitic patch 121a and the second rod-shaped parasitic patch 121b, extending in the Y direction DY. In other words, when the patch antenna 100 is viewed from above, the slit 121s is provided so as to extend along a direction perpendicular to the direction connecting the center point O2 of the first patch 12 (center point O1 of the slit 121s) and the first feed point 51.

[0087] In the fourth main surface 14b, a first rectangular parasitic patch 122a is positioned on one side in the X direction DX, and a second rectangular parasitic patch 122b is positioned on the other side. That is, the first rectangular parasitic patch 122a and the second rectangular parasitic patch 122b are positioned via a rod-shaped parasitic patch 121 along the direction of radio waves (X direction DX) that the patch antenna 100 can transmit and receive.

[0088] In plan view, the first rectangular parasitic patch 122a and the second rectangular parasitic patch 122b have the same shape. Here, let L_X be the dimension of one side in the X direction DX of the first rectangular parasitic patch 122a, and let L_Y be the dimension of one side in the Y direction DY. In this case, L_X corresponds to the side dimension L_CP of the rectangular parasitic patch. Also, the dimension in the Y direction DY of the rod-shaped parasitic patch 121 coincides with L_Y. Furthermore, L_Y also corresponds to the Y direction slit dimension Y_SLT of the slit 121s. In the patch antenna 300 according to the second embodiment, the configuration in which the dimension in the Y direction DY of the rod-shaped parasitic patch 121 and the Y direction slit dimension Y_SLT of the slit 121s coincide with L_Y is used as an example for explanation, but they do not necessarily have to coincide.

[0089] 2.2 Configuration of the Second Comparative Example In order to evaluate the performance of the patch antenna 100 according to the second embodiment of this disclosure, the second comparative example shown in Figure 21 is used. Figure 21 is a schematic top view illustrating the patch antenna 300 according to the second comparative example.

[0090] The patch antenna 300 according to the second comparative example differs from the patch antenna 100 according to the second embodiment only in that it has one rod-shaped parasitic patch 121 and does not have a slit 121s. In all other respects, the patch antenna 300 according to the second comparative example has the same configuration as the patch antenna 100 according to the second embodiment.

[0091] In other words, the patch antenna 300 according to the second comparative example includes a rod-shaped parasitic patch 321 and two rectangular parasitic patches 322 (first rectangular parasitic patch 322a, second rectangular parasitic patch 322b) on the upper surface of the second dielectric layer 314.

[0092] 2.3 Influence of the slit in the rod-shaped parasitic patch Figure 22 shows the S-parameter S of the patch antenna 100 according to the second embodiment. １１ Simulation results of the frequency characteristics and the S-parameters of the patch antenna 300 related to the second comparative example. １１ Figure 23 is a graph showing the simulation results of the frequency characteristics of the patch antenna 100 according to the second embodiment and the relationship between the gain value and frequency characteristics of the patch antenna 300 according to the second comparative example.

[0093] Figures 22 and 23 show the simulation results when the slit width dimension W_SLT of the patch antenna 100 is 0.05 mm, the gap dimension G is 0.05 mm, the slit dimension Y_SLT in the Y direction is 1 mm, the rectangular parasitic patch side dimension L_CP is 0.75 mm, and the parasitic patch width dimension L_CX is 0.125 mm.

[0094] Furthermore, the simulation results are shown for the case where the rectangular parasitic patch side dimension L_CP of the patch antenna 300 according to the second comparative example is 0.75 mm, the gap dimension G is 0.05 mm, the dimension of the rod-shaped parasitic patch 321 in the Y direction DY, in other words, the dimension corresponding to the Y direction slit dimension Y_SLT of the patch antenna 100 according to the second embodiment is 1 mm, and the parasitic patch width dimension L_CX is 0.25 mm.

[0095] As shown in Figure 22, the S-parameters S of the patch antenna 100 １１ When the value of is -10 dB or less, the bandwidth of the frequency response is the S parameter S of the patch antenna 300 according to the second comparative example. １１ The value of this becomes larger than the bandwidth of the frequency response where it is -10 dB or less.

[0096] Furthermore, as shown in Figure 23, for example, when the gain value is 4 dB or more, the bandwidth of the frequency characteristics of patch antenna 100 is larger than the bandwidth of the frequency characteristics of patch antenna 300 according to the second comparative example.

[0097] From the above, it can be seen that by forming a slit 121s in the rod-shaped parasitic patch 121, as in the patch antenna 100, the bandwidth of radio waves that can be transmitted and received in the patch antenna 100 can be widened.

[0098] This disclosure is not limited to the embodiments described above, and may be replaced with configurations that are substantially the same as those shown in the embodiments, configurations that produce the same effects, or configurations that can achieve the same purpose.

Claims

1. An antenna module comprising: a first dielectric layer having a first main surface and a second main surface on the side opposite to the side with the first main surface; a first patch disposed on the first main surface and electrically connected to a power supply port; a ground disposed on the second main surface; a second dielectric layer disposed on the first main surface via the first patch and having a third main surface in contact with the first patch and a fourth main surface on the side opposite to the side with the third main surface; and a second patch disposed on the fourth main surface of the second dielectric layer, wherein the second patch includes a plurality of first parasitic patches disposed on the fourth main surface and a plurality of second parasitic patches disposed via the plurality of first parasitic patches, and two first parasitic patches are disposed between two of the second parasitic patches that are facing each other, with a slit provided between the two first parasitic patches.

2. The antenna module according to claim 1, wherein the slit is provided in the first parasitic patch such that, when the antenna module is viewed from above, it extends in a direction perpendicular to the direction connecting the center point of the first patch and the feed point in the first patch from which current is supplied from the feed port.

3. The antenna module according to claim 1, wherein the plurality of second parasitic patches are arranged on the fourth main surface in accordance with the direction of radio waves that can be transmitted and received by the antenna module.

4. The antenna module according to claim 2, wherein the power supply port includes a first power supply port and a second power supply port, the power supply point includes a first power supply point to which current is supplied from the first power supply port and a second power supply point to which current is supplied from the second power supply port, and the slit includes, when the antenna module is viewed from above, a first slit extending along a first direction perpendicular to the direction connecting the center point of the first patch and the first power supply point, and a second slit extending along a second direction perpendicular to the direction connecting the center point of the first patch and the second power supply point.

5. The antenna module according to claim 4, wherein the plurality of first parasitic patches have an L-shape including a first portion extending along the first direction and a second portion extending along the second direction, and include four first parasitic patches arranged to divide the fourth main surface into four regions, the slit having a cross shape where the first slit extending along the first portion and the second slit extending along the second portion intersect, and each of the plurality of second parasitic patches is arranged in each of the four regions divided by the four first parasitic patches.

6. The antenna module according to claim 5, wherein the difference between the length of the first portion in the first direction and the length of the second portion in the second direction of the first parasitic patch is 0.1 mm or less.

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