Antenna Device

Abstract

An antenna device comprising: a ground plane; a planar first feed element; a planar second feed element; a first feed line connected to the first feed element; and a second feed line connected to the second feed element. The ground plane, the first feed element, and the second feed element are spaced and stacked in this order. At least a part of the second feed line is disposed in the same layer as the ground plane, and is disposed in a position overlapping the first feed element when the ground plane is viewed in plan.

Description

[Technical field]

[0001] The present invention relates to an antenna device. [Background technology]

[0002] A stacked patch antenna capable of radiating radio waves in two different frequency bands is disclosed in the following Patent Document 1. The stacked patch antenna disclosed in Patent Document 1 includes a ground plane, a low-frequency side feed element arranged thereon, and a high-frequency side feed element arranged thereon. The angle between the polarization direction of the high-frequency side feed element and the polarization direction of the low-frequency side feed element is greater than 0° and less than 90°. This suppresses degradation of the antenna characteristics. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 261806 Summary of the Invention [Problem to be solved by the invention]

[0004] When the routing of the feed line connected to the feed element becomes complicated, it becomes difficult to design the pattern of the feed line. For example, there may be a case where an additional conductor layer is required for the feed line. When the degree of freedom of the layout of the feed line is increased, the pattern design becomes easier. An object of the present invention is to provide an antenna device capable of increasing the degree of freedom of the layout of the feed line. [Means for solving the problem]

[0005] According to one aspect of the present invention, A ground plane; A first feed element having a flat plate shape; A flat second feed element; a first feed line connected to the first feed element; a second feed line connected to the second feed element; Equipped with the ground plane, the first feeding element, and the second feeding element are stacked in this order with a gap between them; The antenna device is provided in which at least a portion of the second feed line is arranged in the same layer as the ground plane and is arranged at a position overlapping with the first feed element when the ground plane is viewed in a plan view. Effect of the Invention

[0006] Conventionally, the second feed line is arranged on a layer below the ground plane. In contrast, in an antenna device according to one aspect of the present invention, at least a part of the second feed line is arranged on the same layer as the ground plane. In other words, the degree of freedom in arranging the feed line can be increased. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of an antenna device according to a first embodiment. [Diagram 2] FIG. 2A is a schematic perspective view of the antenna device according to the first embodiment, and FIG. 2B is an equivalent circuit diagram of a second feed line of the antenna device according to the first embodiment. [Diagram 3] 3A and 3B are perspective views showing two simulation models of the antenna device. [Figure 4] 4A and 4B are graphs showing the reflection coefficients of the simulation models of FIGS. 3A and 3B, respectively. [Diagram 5] 5A and 5B are cross-sectional views of an antenna device to be simulated. [Figure 6] FIG. 6 is a graph showing the simulation results of the antenna device that is the subject of the simulation and is shown in FIGS. 5A and 5B. [Figure 7] 7A and 7B are plan views focusing on the positions of the feeding points of the first feeding element and the second feeding element. [Figure 8]FIG. 8 is a graph showing the simulation results of reflection coefficients S(1,1), S(2,2), and S(3,3) when high-frequency signals are input from ports P1, P2, and P3, respectively, when the angle θ=0°. [Figure 9] 9A and 9B are graphs showing simulation results of the transmission coefficients S(1,2) and S(1,3) to ports P2 and P3 when a high-frequency signal is input from port P1. [Figure 10] FIG. 10 is a graph showing the relationship between the transmission coefficients S(1,2) and S(1,3) and the angle θ. [Figure 11] FIG. 11 is a schematic perspective view of an antenna device according to the second embodiment. [Figure 12] FIG. 12A is a schematic perspective view of an antenna device according to the third preferred embodiment, and FIG. 12B is a plan view showing the positional relationship between the first feed element and the second feed element. [Figure 13] FIG. 13 is a cross-sectional view of an antenna module included in a communication device according to the fourth embodiment. [Figure 14] FIG. 14 is a block diagram of a communication device according to the fourth embodiment. [Figure 15] FIG. 15 is a cross-sectional view of an antenna device according to the fifth preferred embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [First Example] An antenna device according to a first embodiment will be described with reference to FIGS. 1 to 10. FIG.

[0009] FIG. 1 is a cross-sectional view of an antenna device according to a first embodiment. The dielectric multilayer substrate 50 includes a first conductor layer 21, a second conductor layer 22, a third conductor layer 23, a flat first feed element 31, and a flat second feed element 32. The first conductor layer 21 includes a ground plane 21G and a second feed line 21A. The ground plane 21G, the first feed element 31, and the second feed element 32 are laminated in this order with a gap between them. The side on which the first feed element 31 is arranged as viewed from the first conductor layer 21 is defined as the upper side.

[0010] A second conductor layer 22 and a third conductor layer 23 are disposed in this order at an interval below a first conductor layer 21. The second conductor layer 22 includes a ground plane 22G, a second power feed line 22A, and first power feed lines 22B and 22C. The third conductor layer 23 includes a ground plane 23G.

[0011] The second feed line 21A is arranged at a position overlapping with the first feed element 31 when the ground plane 21G is viewed from above. For example, the second feed line 21A is arranged inside the outer periphery of the first feed element 31 in a planar view. The second feed line 21A is connected to the second feed line 22A in the second layer through a via V. Furthermore, the second feed line 21A is connected to two feed points 32A and 32B of the second feed element 32 through two vias V passing through a clearance hole provided in the first feed element 31. A high-frequency signal is supplied to the second feed element 32 through the second feed lines 21A and 22A. The two vias V connecting the second feed line 21A to the second feed element 32 are arranged at positions different from the vias V connecting the second feed line 21A to the second feed line 22A in the second layer in a planar view. In a plan view, the first feeding element 31 and the second feeding element 32 partially overlap each other.

[0012] The first feed lines 22B and 22C are connected to feed points 31A and 31B of the first feed element 31 through vias V passing through clearance holes provided in the ground plane 21G of the first layer. A high-frequency signal is supplied to the first feed element 31 through the first feed lines 22B and 22C.

[0013] The dimensions of the first feed element 31 in a plan view are larger than the dimensions of the second feed element 32. That is, the resonant frequency of the first feed element 31 is lower than the resonant frequency of the second feed element 32. For example, the area of ​​the first feed element 31 is larger than the area of ​​the second feed element 32 in a plan view.

[0014] Next, the materials of the dielectric multilayer substrate 50 and the conductor portion will be described. For example, a low-temperature co-fired ceramic multilayer substrate (LTCC multilayer substrate), a multilayer substrate including a resin layer made of a low-dielectric liquid crystal polymer, a multilayer substrate including a resin layer made of a fluorine-based resin, a ceramic multilayer substrate, etc. are used as the dielectric multilayer substrate 50. For example, a metal mainly composed of Al, Cu, Au, Ag, or an alloy of these is used for the conductor portion.

[0015] Fig. 2A is a schematic perspective view of an antenna device according to a first embodiment. In Fig. 2A, the ground planes 21G, 22G, and 23G (Fig. 1) are omitted. The first feed element 31 and the second feed element 32 are both circular. The center of the first feed element 31 and the center of the second feed element 32 coincide with each other in a plan view.

[0016] The second feed line 21A in the first layer has a circumferential shape in a plan view and is disposed inside the outer periphery of the first feed element 31. In FIG. 2A, the second feed line 21A is indicated by a dashed line. The second feed line 22A in the second layer is connected to the second feed line 21A in the second layer through a via V. Furthermore, the second feed line 21A is connected to two feed points 32A and 32B of the second feed element 32 through two vias V, respectively. These two vias V pass through clearance holes provided in the first feed element 31. A high-frequency signal is supplied from the port P1 to the feed points 32A and 32B through the second feed line 22A in the second layer and the second feed line 21A in the first layer.

[0017] 2B is an equivalent circuit diagram of the second feeder line 21A. The second feeder line 21A constitutes a 90° hybrid circuit. That is, the second feeder line 21A has a characteristic impedance of Z 0The two transmission lines have a characteristic impedance of Z 0 / 2 1 / 2 It is composed of two transmission lines. The characteristic impedance is Z 0 / 2 1 / 2 The width of the two transmission lines is 0 The width of the two transmission lines is wider than that of the 0 The two transmission lines have a characteristic impedance of Z 0 / 2 1 / 2 The two transmission lines are alternately connected in a ring shape. The electrical length of each transmission line is ¼ of the wavelength corresponding to the resonant frequency of the second feed element 32.

[0018] A second feed line 22A is connected to one of the four ports of the 90° hybrid circuit. A high-frequency signal is input from port P1 through the second feed line 22A to the 90° hybrid circuit. A characteristic impedance Z 0 / 2 1 / 2 The adjacent ports on either side are connected to a feed point 32A. The port diagonally opposite the port connected to the second feed line 22A is connected to a feed point 32B. The remaining port of the 90° hybrid circuit is designated as Px.

[0019] When a high frequency signal is input from port P1, the phase of the high frequency signal output to one feed point 32B lags behind the phase of the high frequency signal output to the other feed point 32A by 90°. No signal is output to port Px. Conversely, when a high frequency signal having a phase lag of 90° with respect to the high frequency signal input to feed point 32B is input to feed point 32A, the high frequency signal is output from port P1 and is not output to port Px. In this way, the second feed line 21A has the function of supplying high frequency signals to the two feed points 32A and 32B with a phase difference of 90° between them.

[0020] For example, as shown in FIG. 2A, a 90° hybrid circuit is configured by increasing or decreasing the width of a circumferential transmission line every quarter of the circumference. The widths of the parts facing each other across the center of the circumference are equal, and the widths of the adjacent parts are different. That is, the circumferential second feeder line 21A includes two relatively wide parts and two narrow parts. The second feeder line 21A may have a shape other than a circumference, such as a ring shape that follows the outer periphery of a square. In this case, the widths of the parts along the two opposing sides may be equal.

[0021] A line segment having a point connected to the second feed line 22A on the second layer and a point connected to the feed point 32B at its both ends passes through the center of the circumference. The portion from the point connected to the second feed line 22A on the second layer to the point connected to the feed point 32A is relatively thick, and the portions connected to the two feed points 32A and 32B are relatively thin.

[0022] The central angle between the two radii extending from the center of the second feed element 32 toward the two feed points 32A and 32B shown in Fig. 2A is 90°. Since high-frequency signals having a phase difference of 90° are supplied to the two feed points 32A and 32B, the radio wave radiated from the second feed element 32 becomes a circularly polarized wave.

[0023] 2A, the central angle formed by two radii extending from the center of first feed element 31 to two feed points 31A and 31B is 90°. When a high-frequency signal is supplied to one of feed points 31A and 31B, the radio wave radiated from first feed element 31 becomes linearly polarized. When high-frequency signals with a phase difference of 90° are supplied to each of feed points 31A and 31B, the radio wave radiated from first feed element 31 becomes circularly polarized.

[0024] A stacked patch antenna is configured by a first-layer ground plane 21G (FIG. 1), a first feed element 31, and a second feed element 32. In a typical stacked patch antenna, the ground plane 21G (FIG. 1) is arranged over the entire area overlapping with the first feed element 31 in a plan view, excluding a clearance hole through which a feed via V passes. In contrast, in the first embodiment, the second feed line 21A is arranged on the same first conductor layer 21 (FIG. 1) as the ground plane 21G.

[0025] Hereinafter, the influence on the antenna characteristics of the configuration in which the second feed line 21A is arranged on the same first conductor layer 21 as the ground plane 21G will be described.

[0026] When a high-frequency signal is supplied to the first feed element 31, an electric field is concentrated between its edge and the ground plane 21G. Since the electric field is not concentrated in the region where the second feed line 21A is arranged, the second feed line 21A has a small effect on the operation of the first feed element 31. A simulation was performed to confirm that the second feed line 21A has a small effect on the operation of the first feed element 31. The results of this simulation will be described with reference to Figures 3A to 4B.

[0027] 3A and 3B are perspective views showing two simulation models of the antenna device. In the simulation model shown in FIG. 3A, a second feed line 21A is arranged on a first conductor layer 21 (FIG. 1) as in the antenna device according to the first embodiment (FIGS. 1 and 2). A high-frequency signal is supplied from a port P1 to two feed points 32A and 32B of a second feed element 32 via a second feed line 22A of a second layer and a second feed line 21A of a first layer. A high-frequency signal is supplied from ports P2 and P3 to two feed points 31A and 31B of a first feed element 31 via first feed lines 22B and 22C, respectively.

[0028] In the simulation model shown in Fig. 3B, the second feed line 21A (Fig. 3A) in the first layer is not arranged. High-frequency signals are supplied from two ports P1 and P6 to two feed points 32A and 32B of the second feed element 32 via second feed lines 22A and 22D, respectively. The reflection coefficients S(2,2) and S(3,3) when high-frequency signals are input from ports P2 and P3 were obtained.

[0029] 4A and 4B are graphs showing the reflection coefficients of the simulation models of FIGS. 3A and 3B, respectively. The horizontal axis represents frequency in units of "GHz", and the vertical axis represents the S parameter value in units of "dB". In both the simulation models of FIGS. 3A and 3B, the reflection coefficients S(2,2) and S(3,3) show downward peaks at the resonance frequency of 40 GHz of the first feed element 31. This simulation confirmed that the operation of the first feed element 31 is not significantly affected even if the second feed line 21A is placed on the first conductor layer 21, which is the same as the ground plane 21G (FIG. 1).

[0030] In addition, in a typical patch antenna, a ground plane is arranged between the feed element and the feed line to improve isolation between them. However, in the antenna device according to the first embodiment, a ground plane is not arranged between the second feed element 32 (FIG. 1) and the second feed line 21A (FIG. 1). Next, with reference to FIGS. 5A to 6, the influence on the antenna characteristics of a configuration in which a ground plane is not arranged between the second feed element 32 and the second feed line 21A will be described.

[0031] A simulation was performed to confirm the degree of isolation between the second feed element 32 and the second feed line 21A. 5A and 5B are cross-sectional views of a simulation model of an antenna device. In the simulation model shown in Fig. 5A, instead of the second feed line 21A of the antenna device according to the first embodiment, a wiring 21X is arranged on the first conductor layer 21. Both ends of the wiring 21X are connected to wirings 22X and 22Y arranged on the second conductor layer 22, respectively.

[0032] The first feed element 31 is disposed between the ground plane 21G and the wiring 21X disposed on the first conductor layer 21, and the second feed element 32. A high-frequency signal is supplied to the second feed element 32 from the second feed line 22A disposed on the second conductor layer 22 through a via V penetrating the ground plane 21G and the first feed element 31. The resonant frequency of the first feed element 31 is 40 GHz, and the resonant frequency of the second feed element 32 is 60 GHz.

[0033] In the simulation model shown in FIG. 5B, the first feeding element 31 is removed from the simulation model shown in FIG. 5A.

[0034] The second feed line 22A is connected to the port P1, and the wirings 22X and 22Y are connected to the ports P4 and P5, respectively. The S parameters S(1,4) and S(1,5) from the port P1 to the ports P4 and P5 when a high-frequency signal is input from the port P1 were obtained by simulation.

[0035] Figure 6 is a graph showing the simulation results. The horizontal axis represents frequency in units of "GHz", and the vertical axis represents the calculated values ​​of S parameters in units of "dB". The thick solid line and thin solid line in the graph of Figure 6 respectively represent the transmission coefficients S(1,4) and S(1,5) of the simulation model shown in Figure 5A. The thick dashed line and thin dashed line respectively represent the transmission coefficients S(1,4) and S(1,5) of the simulation model shown in Figure 5B.

[0036] It can be seen that in the simulation model (FIG. 5A) in which the first feed element 31 is arranged, S(1,4) and S(1,5) are reduced by about 10 dB in the vicinity of the resonant frequency of 60 GHz of the second feed element 32, compared to the simulation model (FIG. 5B) in which the first feed element 31 is not arranged. This means that the isolation between the second feed element 32 and the wiring 21X is high.

[0037] As shown in Fig. 5A, it was confirmed that when the first feed element 31 is disposed between the second feed element 32 and the wiring 21X, the isolation between them is increased. This means that in the antenna device according to the first embodiment (Figs. 1 and 2), the decrease in isolation between the second feed element 32 and the second feed line 21A is suppressed. At a resonant frequency of 60 GHz of the second feed element 32, S(1,4) and S(1,5) are -35 dB or less. This means that sufficient isolation between the second feed element 32 and the second feed line 21A is ensured in the antenna device according to the first embodiment.

[0038] Next, a preferred positional relationship between feeding points 31A, 31B of first feeding element 31 and feeding points 32A, 32B of second feeding element 32 will be described with reference to FIGS. 7A to 10. FIG.

[0039] 7A and 7B are plan views focusing on the positions of the feed points of the first feed element 31 and the second feed element 32. The geometric center of the first feed element 31 and the second feed element 32 in a plan view is marked as O. The central angle α formed by two radii from the geometric center O toward the two feed points 31A and 31B of the first feed element 31, and the central angle α formed by two radii from the geometric center O toward the two feed points 32A and 32B of the second feed element 32 are both 90°.

[0040] Fig. 7A shows a state in which, in a plan view, the geometric center O, one feed point 31A of the first feed element 31, and one feed point 32A of the second feed element 32 are located on a straight line, and the geometric center O, the other feed point 31B of the first feed element 31, and the other feed point 32B of the second feed element 32 are also located on a straight line. Fig. 7B shows a state in which the two feed points 31A and 31B of the first feed element 31 are rotated by an angle θ around the geometric center O. The state shown in Fig. 7A corresponds to a state in which the angle θ=0°.

[0041] A high-frequency signal is supplied from port P1 via second feed lines 22A and 21A to two feed points 32A and 32B of second feed element 32. A high-frequency signal is supplied from ports P2 and P3 to feed points 31A and 31B of first feed element 31 via first feed lines 22B and 22C, respectively.

[0042] FIG. 8 is a graph showing the simulation results of the reflection coefficients S(1,1), S(2,2), and S(3,3) when high-frequency signals are input from ports P1, P2, and P3, respectively, when the angle θ is 0°. The horizontal axis represents frequency in units of "GHz", and the vertical axis represents the calculated value of the S parameter in units of "dB". The solid line, thick dashed line, and thin dashed line in the graph represent the reflection coefficients S(1,1), S(2,2), and S(3,3), respectively. It can be seen that the first feed element 31 resonates at a frequency of about 40 GHz, and the second feed element 32 resonates at a frequency of about 60 GHz. The tendency of the reflection coefficients S(1,1), S(2,2), and S(3,3) did not change significantly even when the angle θ was changed.

[0043] Figures 9A and 9B are graphs showing the simulation results of the transmission coefficients S(1,2) and S(1,3) to ports P2 and P3 when a high-frequency signal is input from port P1. The horizontal axis represents frequency in units of "GHz", and the vertical axis represents the calculated S-parameter values ​​in units of "dB". The solid and dashed lines in the graphs represent the transmission coefficients S(1,2) and S(1,3), respectively. Figure 9A shows the simulation results when angle θ = 0°, and Figure 9B shows the simulation results when angle θ = 45°.

[0044] A high-frequency signal supplied from port P1 to second feed element 32 is coupled to first feed element 31 and output from ports P2 and P3. Since high isolation between first feed element 31 and second feed element 32 is preferable, it is preferable that transmission coefficients S(1,2) and S(1,3) are small. At a resonance frequency of 60 GHz of second feed element 32, when angle θ=0°, S(1,2)=-13.5 dB and S(1,3)=-10.62 dB. On the other hand, when angle θ=45°, S(1,2)=-19.59 dB and S(1,3)=-17.64 dB. From this result, it can be seen that setting angle θ to 45° is more preferable than setting it to 0° in terms of increasing isolation.

[0045] The angle θ was changed from 0° to 360° to find the transmission coefficients S(1,2) and S(1,3).

[0046] FIG. 10 is a graph showing the relationship between the transmission coefficients S(1,2) and S(1,3) and the angle θ. The horizontal axis represents the angle θ in degrees, and the vertical axis represents the calculated S-parameters in dB. The thick dashed line and thin dashed line in the graph represent the transmission coefficients S(1,2) and S(1,3), respectively. The thick solid line in the graph is a line connecting the transmission coefficients S(1,2) and S(1,3) that have the larger value (i.e., the worse characteristic). The transmission coefficient S(1,2) and S(1,3) that has the larger value is denoted as SL. In other words, SL=max(S(1,2), S(1,3)). It can be seen that the transmission coefficient SL is small at R45, R135, R225, and R315, which are in the vicinity of angles θ of 45°, 135°, 225°, and 315°. That is, it is understood that the passage coefficient SL is small when the angle θ is in the vicinity of 45°+90°×n (n=0, 1, 2, 3).

[0047] In addition, the transmission coefficient SL is smaller in the range of angle θ=45°+90°×n±10° than when angle θ=0°+90°×n. That is, the range of angle θ=45°+90°×n±10° is superior in terms of improving isolation. In order to improve isolation, it is preferable to arrange the feed points so that the angle (the angle less than 90°) between a line passing through either the geometric center O of the first feed element 31 or the feed points 31A, 31B and a line passing through either the geometric center O of the second feed element 32 or the feed points 32A, 32B is 35° or more and 55° or less.

[0048] Next, the excellent effects of the first embodiment will be described. In the first embodiment, the second feed line 21A is arranged on the first conductor layer 21, which is the same as the ground plane 21G (FIG. 1) that functions as a ground for the first feed element 31. The degree of freedom in arranging the feed line is increased compared to the case where the arrangement of the feed line on the first conductor layer 21 is prohibited. Since it is not necessary to arrange the second feed line 21A on another conductor layer, an excellent effect is obtained in that the degree of freedom in arranging the wiring on the other conductor layers is increased. As a result, it is possible to suppress an increase in the number of conductor layers, and it is possible to make the antenna device thinner. In addition, as described with reference to the drawings from FIG. 3A to FIG. 6, even if the second feed line 21A is arranged on the first conductor layer 21, which is the same as the ground plane 21G, the influence on the antenna characteristics is small.

[0049] Next, a modification of the first embodiment will be described. In the first embodiment, the second feed line 21A, which supplies high-frequency signals with a phase difference of 90° to the two feed points 32A and 32B of the second feed element 32, is configured as a 90° hybrid circuit, but a transmission line of another configuration may be used as the second feed line 21A. For example, one transmission line may be branched into two transmission lines, and the two branched transmission lines may be connected to the feed points 32A and 32B, respectively. In this case, in order to radiate a circularly polarized wave, the difference in electrical length between the two transmission lines from the branch point to the two second feed points 32A and 32B may be set to ¼ of the wavelength corresponding to the resonant frequency of the second feed element 32.

[0050] A parasitic element may be loaded onto the second feed element 32. By causing double resonance between the second feed element 32 and the parasitic element, it is possible to achieve a wider bandwidth.

[0051] [Second Example] Next, an antenna device according to a second embodiment will be described with reference to Fig. 11. Below, a description of the configuration common to the antenna device according to the first embodiment described with reference to Figs. 1 to 10 will be omitted.

[0052] Fig. 11 is a schematic perspective view of an antenna device according to the second embodiment. In the antenna device according to the first embodiment (Fig. 2), the first feed element 31 is provided with two feed points 31A and 31B, and the second feed element 32 is provided with two feed points 32A and 32B. In contrast, in the second embodiment, the first feed element 31 is provided with one feed point 31A, and the second feed element 32 is provided with one feed point 32A.

[0053] In the first embodiment, the second feed line 21A (FIG. 2) arranged on the first conductor layer 21 is circumferential, but in the second embodiment, the second feed line 21A is, for example, linear. One end of the second feed line 21A is connected to a feed point 32A of the second feed element 32 through a via V. The other end of the second feed line 21A is connected to a second feed line 22A of the second layer through a via V. A wiring 22E arranged on the second conductor layer 22 intersects with the second feed line 21A arranged on the first conductor layer 21 in a plan view.

[0054] The feed point 32A and the second feed line 22A in the second layer are disposed on opposite sides of each other when viewed from the wiring 22E. In a plan view, an angle between a line passing through the geometric center O of the first feed element 31 and the feed point 31A and a line passing through the geometric center O of the second feed element 32 and the feed point 32A is denoted as θ. Changing the angle θ changes the isolation between the first feed element 31 and the second feed element 32.

[0055] Next, the advantageous effects of the second embodiment will be described. In the second embodiment, similarly to the first embodiment, the second feed line 21A is arranged on the same first conductor layer 21 (FIG. 1) as the ground plane 21G (FIG. 1). This provides an excellent effect of increasing the degree of freedom in arranging the feed line. For example, the wiring 22E intersecting the second feed line 21A can be arranged on the same second conductor layer 22 (FIG. 1) as the second feed line 22A.

[0056] In the second embodiment, linearly polarized radio waves are radiated from the first feed element 31 and the second feed element 32. When the polarization planes of the two linearly polarized waves are orthogonal to each other, the isolation between the first feed element 31 and the second feed element 32 is highest. In order to increase the isolation, it is preferable to set the angle θ to 90°. Note that, based on the same concept as in the first embodiment described with reference to FIG. 10, it is preferable to set the angle θ to 80° or more and 100° or less.

[0057] Next, a modified example of the second embodiment will be described. In the second embodiment, the first feeding element 31 and the second feeding element 32 each have one feeding point, but two feeding points may be provided on one of the feeding elements. When the second feeding element 32 has two feeding points, it is preferable to arrange the second feeding line 21A so that there is a phase difference of 90° between the high-frequency signals supplied to the two feeding points, as in the first embodiment (FIG. 2).

[0058] [Third Example] Next, an antenna device according to a third embodiment will be described with reference to Figures 12A and 12B. Below, a description of the configuration common to the antenna device according to the first embodiment described with reference to Figures 1 to 10 will be omitted.

[0059] 12A is a schematic perspective view of an antenna device according to the third embodiment, and FIG. 12B is a plan view showing the positional relationship between the first feed element 31 and the second feed element 32. In the antenna device according to the first embodiment, the first feed element 31 and the second feed element 32 are circular. In contrast, in the third embodiment, the first feed element 31 and the second feed element 32 are square. Two feed points 31A and 31B of the first feed element 31 are disposed on a line segment connecting the midpoints of two adjacent sides of the first feed element 31 and the geometric center O of the first feed element 31. Similarly, two feed points 32A and 32B of the second feed element 32 are disposed on a line segment connecting the midpoints of two adjacent sides of the second feed element 32 and the geometric center O of the second feed element 32.

[0060] As in the first embodiment, an angle (less than 90°) between a line passing through the geometric center O of the first feed element 31 and one feed point 31A of the first feed element 31 and a line passing through the geometric center O of the second feed element 32 and one feed point 32A of the second feed element 32 is denoted as θ. In the first embodiment, the second feed element 32 is disposed inside the perimeter of the first feed element 31 in a planar view. In contrast, in the third embodiment, the vicinity of the apex of the second feed element 32 may protrude outside the first feed element 31 in a planar view.

[0061] As in the first embodiment, the second feed line 21A is disposed on the same first conductor layer 21 as the ground plane 21G. In Fig. 12A, the second feed line 21A is shown linearly, but the second feed line 21A may be circumferentially disposed as in the first embodiment (Fig. 2).

[0062] Next, the excellent effects of the third embodiment will be described. Similarly to the first embodiment, the third embodiment also has the excellent effect of increasing the degree of freedom in arranging the feed line. In order to increase the isolation between the first feed element 31 and the second feed element 32, it is preferable that the angle θ is set to 35° or more and 55° or less.

[0063] Next, a modified example of the third embodiment will be described. In the third embodiment, the first feed element 31 and the second feed element 32 are square in plan view, but may be other shapes. For example, they may be rectangular, square with square corners cut out, etc. In addition, one of the first feed element 31 and the second feed element 32 may be open-ended and the other may be circular. The first feed element 31 and the second feed element 32 can be formed in various shapes, but in any shape, it is preferable that the resonant frequency of the first feed element 31 is lower than the resonant frequency of the second feed element 32.

[0064] [Fourth Example] Next, a communication device according to a fourth embodiment will be described with reference to Fig. 13 and Fig. 14. The communication device according to the fourth embodiment includes an antenna device according to any one of the first to third embodiments, or an antenna device according to a modified example thereof.

[0065] 13 is a cross-sectional view of an antenna module 100 included in a communication device according to a fourth embodiment. A plurality of antenna elements 30 are provided on a single dielectric multilayer substrate 50. The plurality of antenna elements 30 are arranged in a one-dimensional or two-dimensional array to form an array antenna.

[0066] Each of the multiple antenna elements 30 includes a first feed element 31 and a second feed element 32. The dielectric multilayer substrate 50 includes therein a first conductor layer 21 and a multilayer wiring structure below the first conductor layer 21. The first conductor layer 21 includes a ground plane 21G and a second feed line 21A arranged for each antenna element 30. The configurations of the ground plane 21G, the second feed line 21A, the first feed element 31 and the second feed element 32 are the same as the configuration of the antenna device according to any one of the first to third embodiments.

[0067] A radio frequency integrated circuit element (RFIC) 110 is mounted on the lower surface of the dielectric multilayer substrate 50. The radio frequency integrated circuit element 110 is connected to a first feed element 31 and a second feed element 32 of the multiple antenna elements 30 via wiring provided in the dielectric multilayer substrate 50.

[0068] 14 is a block diagram of a communication device according to the fourth embodiment. The communication device according to the fourth embodiment includes an antenna module 100 and a baseband integrated circuit device (BBIC) 135. The antenna module 100 includes a high frequency integrated circuit device 110 and an antenna device 130. The antenna device 130 includes a plurality of antenna elements 30.

[0069] The antenna module 100 up-converts a baseband signal or an intermediate frequency signal input from the baseband integrated circuit element 135 to a high-frequency signal and transmits it from the antenna device 130. Furthermore, the antenna module 100 down-converts a high-frequency signal received by the antenna device 130 and outputs it to the baseband integrated circuit element 135.

[0070] Next, the configuration and functions of the high frequency integrated circuit element 110 will be described. The high frequency integrated circuit element 110 includes a plurality of transmitting and receiving systems 120. Each of the plurality of transmitting and receiving systems 120 includes a phase shifter 115, an attenuator 114, a switch 113, a power amplifier 112T, a low noise amplifier 112R, and a switch 111. Each of the four transmitting and receiving systems includes a combiner / demultiplexer 116, a switch 117, a mixer 118, and an amplifier circuit 119. The plurality of transmitting and receiving systems 120 includes a transmitting and receiving system 120 that processes a transmitting and receiving signal by a first feeding element 31 on the low frequency side of the antenna element 30, and a transmitting and receiving system 120 that processes a transmitting and receiving signal by a second feeding element 32 on the high frequency side.

[0071] A signal to be transmitted is input from the baseband integrated circuit element 135 to the amplifier circuit 119. The amplifier circuit 119 amplifies the input signal, and the mixer 118 up-converts the amplified signal. The up-converted high-frequency signal is input to the combiner / demultiplexer 116 via the switch 117. The multiple high-frequency signals demultiplexed by the combiner / demultiplexer 116 are each input to the phase shifter 115 of the transmission / reception system 120.

[0072] The high frequency signal that has been subjected to a predetermined phase delay by the phase shifter 115 is supplied to the antenna element 30 of the antenna device 130 via the attenuator 114, the switch 113, the power amplifier 112T and the switch 111.

[0073] A high-frequency signal received by antenna element 30 is input to combiner / demultiplexer 116 via switch 111, low-noise amplifier 112R, switch 113, attenuator 114, and phase shifter 115. The received signal combined by combiner / demultiplexer 116 is input to mixer 118 via switch 117. Mixer 118 down-converts the received signal. The signal down-converted by mixer 118 is input to baseband integrated circuit element 135 via amplifier circuit 119.

[0074] Next, the excellent effects of the fourth embodiment will be described. The communication device according to the fourth embodiment is equipped with an antenna device according to any one of the first to third embodiments. Therefore, as with the first to third embodiments, an excellent effect is obtained in that the degree of freedom in arranging the power feed lines in the antenna device is increased. This makes it possible to suppress an increase in the number of conductor layers in the dielectric multilayer substrate 50 (FIG. 13). Since an increase in the number of conductor layers is suppressed, it becomes possible to make the antenna module thinner.

[0075] [Fifth Example] Next, an antenna device according to a fifth embodiment will be described with reference to Fig. 15. Below, a description of the configuration common to the antenna device according to the first embodiment described with reference to Figs. 1 to 10 will be omitted.

[0076] Fig. 15 is a cross-sectional view of an antenna device according to a fifth embodiment. The antenna device according to the first embodiment (Fig. 1) includes two feed elements, a first feed element 31 and a second feed element 32. In contrast, the antenna device according to the fifth embodiment includes, in addition to the first feed element 31 and the second feed element 32, a flat third feed element 33 arranged at a distance from the second feed element 32. In a plan view, the third feed element 33 partially overlaps with the second feed element 32. That is, the first feed element 31, the second feed element 32, and the third feed element 33 are stacked in this order.

[0077] A third feed line 24A is disposed under the third conductor layer 23. The third feed line 24A is connected to a third feed element 33 through a via V passing through clearance holes provided in the ground planes 23G, 22G, and 21G, the first feed element 31, and the second feed element 32.

[0078] The resonant frequency of the third feed element 33 is higher than the resonant frequency of the second feed element 32. For example, the area of ​​the third feed element 33 is smaller than the area of ​​the second feed element 32 in a plan view.

[0079] Next, the excellent effects of the fifth embodiment will be described. The antenna device according to the fifth embodiment can transmit and receive radio waves in three frequency bands. In addition, since the second feed line 21A is arranged on the same first conductor layer 21 as the ground plane 21G as in the first embodiment, the antenna device according to the fifth embodiment has an excellent effect of increasing the freedom of arrangement of the feed line.

[0080] Next, a modified example of the fifth embodiment will be described. In the fifth embodiment, the resonant frequency of the third feed element 33 is higher than the resonant frequency of the second feed element 32. However, the resonant frequency of the second feed element 32 may be higher than the resonant frequency of the third feed element 33. In this case, the resonant frequency of the first feed element 31 is lower than both the resonant frequencies of the second feed element 32 and the third feed element 33.

[0081] In the fifth embodiment, a second feed line 21A connected to a second feed element 32 is arranged on the same first conductor layer 21 as the ground plane 21G. Instead of the second feed line 21A, or in addition to the second feed line 21A, a feed line connected to a third feed element 33 may be arranged on the first conductor layer 21. In this case, the feed line arranged on the first conductor layer 21 may be arranged inside the outer periphery of the first feed element 31 in a plan view.

[0082] In the fifth embodiment, three feed elements, namely, the first feed element 31, the second feed element 32, and the third feed element 33, are stacked, but four or more plate-shaped feed elements may be stacked. Also, in the fifth embodiment, the third feed line 24A connected to the third feed element 33 is disposed below the third conductor layer 23, but it may be disposed on the second conductor layer 22.

[0083] The above-mentioned embodiments are merely examples, and it goes without saying that partial replacement or combination of the configurations shown in different embodiments is possible. Similar effects due to similar configurations of multiple embodiments are not mentioned in each embodiment. Furthermore, the present invention is not limited to the above-mentioned embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible. [Explanation of symbols]

[0084] 21 1st conductor layer 21A 1st layer 2nd feeder line 21G Ground Plane 21X Wiring 22 Second conductor layer 22A 2nd layer 2nd feeder line 22B, 22C First power supply line 22D Second feeder line on the second layer 22E Wiring 22G Ground Plane 22X, 22Y wiring 23 3rd conductor layer 23G Ground Plane 24A 3rd power feed line 30 Antenna elements 31 First feed element 31A, 31B power supply points 32 Second feed element 32A, 32B feed points 33 Third feed element 50 Dielectric multilayer board 100 Antenna Module 110 Radio Frequency Integrated Circuits (RFIC) 111 Switch 112T Power Amplifier 112R Low Noise Amplifier 113 Switch 114 Attenuator 115 Phase shifter 116 Synthetic demultiplexer 117 Switch 118 Mixer 119 Amplification circuit 120 Transmitting and receiving system 130 Antenna equipment 135 Baseband Integrated Circuit (BBIC)

Claims

1. A ground plane; A first feed element having a flat plate shape; A second feed element having a flat plate shape; a first feed line connected to the first feed element; a second feed line connected to the second feed element; Equipped with the ground plane, the first feeding element, and the second feeding element are stacked in this order with a gap therebetween; The antenna device, wherein at least a portion of the second feed line is arranged in the same layer as the ground plane and is arranged at a position overlapping with the first feed element when the ground plane is viewed in a plan view.

2. The antenna device according to claim 1 , wherein a resonant frequency of the first feed element is lower than a resonant frequency of the second feed element.

3. The antenna device according to claim 1 , wherein an area of ​​the first feed element is larger than an area of ​​the second feed element in a plan view.

4. 3. The antenna device according to claim 1, wherein the second feed line is connected to two second feed points of the second feed element, and two straight lines passing through a geometric center of the second feed element and the two second feed points are perpendicular to each other.

5. 5. The antenna device according to claim 4, wherein the second feed line supplies a high-frequency signal having a resonant frequency of the second feed element to the two second feed points with a phase difference of 90 degrees.

6. 5. The antenna device according to claim 4, wherein the second feed line includes a 90° hybrid circuit having four ports, a high-frequency signal is input to one port of the 90° hybrid circuit, and the other two ports are connected to the two second feed points, respectively.

7. 5. The antenna device according to claim 4, wherein the second feed line includes a ring-shaped transmission line in which two relatively thick transmission lines and two relatively thin transmission lines are alternately connected, and the transmission line between a point where a high-frequency signal is input to the second feed line and a point connected to one of the two second feed points is relatively thick, and the transmission line connected between the two second feed points is relatively thin.

8. 5. The antenna device according to claim 4, wherein the second feed line includes a portion that branches off from a single line to reach the two second feed points, and a difference in electrical length from the branch point to the two second feed points is ¼ of a wavelength of a high-frequency signal having a resonant frequency of the second feed element.

9. the first feed line is connected to at least one first feed point of the first feed element; 5. The antenna device according to claim 4, wherein, in a plan view, an angle between a line passing through a geometric center of the first feed element and the first feed point and a line passing through a geometric center of the second feed element and one of the second feed points is 35° or more and 55° or less.

10. The antenna device according to claim 9 , wherein two first feed points are provided, and two straight lines passing through the geometric center of the first feed element and each of the first feed points are perpendicular to each other.

11. moreover, a third feed element having a flat plate shape that is spaced apart from the second feed element and that partially overlaps with the second feed element in a plan view; a third feed line connected to the third feed element; 3. The antenna device according to claim 1, further comprising:

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