Antenna

Abstract

To reduce the size of an antenna having rectangular patch elements.SOLUTION: An antenna comprises: a patch element; a first dielectric substrate on which the patch element is formed; a power feeding circuit for feeding power to the patch element and including a 90-degree hybrid circuit; a second dielectric substrate on which the 90-degree hybrid circuit is formed; and a pair of power feeding probe for sending a power feeding signal from the 90-degree hybrid circuit to the patch element. The first dielectric substrate and the second dielectric substrate are arranged by being spaced apart in the thickness direction. At least a section of the 90-degree hybrid circuit is formed at a position overlapping the patch element as seen in a direction orthogonal to the patch element.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] In recent years, satellite IoT platforms (satellite IoT-PF) have been under study. Satellite IoT-PFs use low-orbit satellites to collect sensor data from IoT terminals located anywhere on Earth, including areas that are difficult to cover with terrestrial communication networks (such as on the sea and in mountainous areas). With satellite IoT-PFs, reception can be affected by interference between satellite IoT terminals and interference signals from terrestrial IoT terminals. In order to receive weak radio waves transmitted by satellite IoT terminals with low-orbit satellites, it is effective to equip the low-orbit satellites with multiple receiving antennas and perform receiving beam control (see, for example, Non-Patent Document 1).

[0003] Since low-orbit satellites are generally required to be small and lightweight, miniaturization of the antenna is required to mount a complex receiving antenna on a small low-orbit satellite. In satellite IoT-PF, in order to enable the use of satellite IoT terminals in each country, antennas that are compatible with the frequency bands used in each country and that can perform the circular polarization required for satellite communications (multi-frequency circularly polarized antennas) are sometimes used.

[0004] Typical components of a multi-frequency circularly polarized antenna include a square patch antenna and a circular patch antenna. In a square patch antenna, a patch element made of a square conductor plate is used as the radiating element. In a circular patch antenna, a patch element made of a circular conductor plate is used as the radiating element. When constructing a multi-frequency circularly polarized antenna using a square or circular patch antenna, miniaturization of the patch element (radiating element) is required to realize a compact antenna.

[0005] When comparing a square patch antenna and a circular patch antenna with the same operating frequency, the square patch element has smaller dimensions than the circular patch element. Therefore, from the viewpoint of antenna miniaturization, it is desirable to use a square patch antenna. In the case of a square patch antenna, by miniaturizing the square patch element, it is possible to further miniaturize the multi-frequency circularly polarized antenna. As a structure that can miniaturize the square patch element, there is a structure in which an L-shaped slot is formed in the square patch element (for example, see Non-Patent Document 2).

[0006] When using a square patch antenna as a multi-frequency circularly polarized antenna, it is necessary to make the square patch element circularly polarized. One method for achieving circularly polarized radiation with a square patch element is to cut off the corners of the square patch element by an appropriate area and feed power at one feeding point (single-point feeding method). In this method, circularly polarized radiation is achieved by generating orthogonal currents (modes) in the square patch element that have equal amplitudes and a phase difference of 90 degrees.

[0007] One method for achieving circularly polarized radiation from a rectangular patch element is to use a 90-degree hybrid circuit to generate two signals with equal amplitude and a phase difference of 90 degrees, and to excite the patch element at two feeding points on the rectangular patch element with these signals (two-point feeding method). In this method, circularly polarized radiation is achieved by generating currents (modes) with equal amplitude and a phase difference of 90 degrees on the rectangular patch element (see, for example, Non-Patent Document 3).

[0008] As mentioned above, there are two methods for achieving circular polarization in a square patch antenna: a single-point feed method and a two-point feed method, but it is preferable to use the two-point feed method. A square patch antenna circularly polarized by the two-point feed method is generally capable of circular polarization operation over a wide band. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] J. Chu, X. Chen, C. Zhong and Z. Zhang, "Robust Design for NOMA-Based Multibeam LEO Satellite Internet of Things", IEEE Internet of Things Journal, vol. 8, no. 3, pp. 1959-1970, 2021. [Non-Patent Document 2] G. Kumar and KP Ray, “Broadband Microstrip Antennas”, Artech House, pp.336-337, 2003. [Non-Patent Document 3] RA Sainati, “CAD of Microstrip Antennas for Wireless Applications”, Artech House, pp.127-129, 1996. Summary of the Invention [Problem to be solved by the invention]

[0010] However, the above-mentioned circularly polarized patch antenna has a problem in that it tends to be large in size because it has a feed circuit (90-degree hybrid circuit), a patch element, and the like.

[0011] In view of the above circumstances, an object of the present invention is to provide a technique that enables miniaturization of an antenna having a rectangular patch element. [Means for solving the problem]

[0012] One aspect of the present invention is an antenna comprising: a patch element, a first dielectric substrate on which the patch element is formed, a feed circuit including a 90-degree hybrid circuit and feeding power to the patch element, a second dielectric substrate on which the 90-degree hybrid circuit is formed, and a pair of feed probes that send feed signals from the 90-degree hybrid circuit to the patch element, wherein the first dielectric substrate and the second dielectric substrate are arranged at a distance from each other in the thickness direction, and at least a portion of the 90-degree hybrid circuit is formed in a position that overlaps with the patch element when viewed from a direction perpendicular to the patch element. Effect of the Invention

[0013] The present invention allows for miniaturization of antennas having rectangular patch elements. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a plan view of the antenna according to the first embodiment. [Diagram 2] FIG. 2 is a side cross-sectional view illustrating a schematic structure of the antenna according to the first embodiment. [Diagram 3] FIG. 2 is a plan view of the antenna according to the first embodiment. [Figure 4] FIG. 2 is a side cross-sectional view illustrating a schematic structure of the antenna according to the first embodiment. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 11 is a plan view of an antenna according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] (First embodiment) Fig. 1 is a plan view of an antenna 100 according to a first embodiment. Fig. 2 is a side cross-sectional view showing a schematic structure of the antenna 100.

[0016] As shown in Figures 1 and 2, antenna 100 includes a patch element 1, a first dielectric substrate 2, a feed circuit 3, a second dielectric substrate 4 (see Figure 2), a ground conductor plate 5 (see Figure 2), and a pair of feed probes 6 (see Figure 2).

[0017] The left-right direction in FIG. 1 is the x-direction. The x-direction is the direction along the first side (first peripheral edge 1a) of patch element 1. The up-down direction in FIG. 1 is the y-direction. The y-direction is perpendicular to the x-direction. The x-direction and y-directions are parallel to first main surface 2a of first dielectric substrate 2. The xy-plane is a plane defined by the x-direction and y-direction. The z-direction is a direction perpendicular to the x-direction and y-direction. The z-direction is a direction perpendicular to patch element 1. Viewing from the z-direction is called "planar view."

[0018] The right direction in Figure 1 is the +x direction. The opposite direction to the +x direction is the -x direction. The up direction in Figure 1 is the +y direction. The opposite direction to the +y direction is the -y direction. The up direction in Figure 2 is the +z direction. The opposite direction to the +z direction is the -z direction. 2, the positional relationship of each component of the antenna 100 is provisionally defined. The +z direction is upward. The first dielectric substrate 2 is above the second dielectric substrate 4. The positional relationship defined here does not limit the orientation of the antenna 100 during use.

[0019] As shown in FIG. 1, the first dielectric substrate 2 is formed of a dielectric material. In a plan view, the first dielectric substrate 2 has a rectangular shape having a pair of sides parallel to the x direction and a pair of sides parallel to the y direction. The upper surface of the first dielectric substrate 2 is a first main surface 2a. The lower surface of the first dielectric substrate 2 (the surface opposite to the first main surface 2a) is a second main surface 2b (see FIG. 2). The first dielectric substrate 2 is parallel to the xy plane.

[0020] The patch element 1 is formed on the first principal surface 2a of the first dielectric substrate 2. The patch element 1 is formed in a rectangular shape in a plan view. The patch element 1 is formed of a conductor. The dimension of the patch element 1 in the x direction is smaller than the dimension of the first dielectric substrate 2 in the x direction. The dimension of the patch element 1 in the y direction is smaller than the dimension of the first dielectric substrate 2 in the y direction. The patch element 1 is formed in a region including the center of the first principal surface 2a. The center C3 of the patch element 1 coincides with, for example, the center of the first dielectric substrate 2. The patch element 1 is formed along the xy plane.

[0021] Patch element 1 has a rectangular shape having a first side (first periphery 1a), a second side (second periphery 1b), a third side (third periphery 1c), and a fourth side (fourth periphery 1d). First periphery 1a and third periphery 1c are parallel to the x direction. Second periphery 1b and fourth periphery 1d are parallel to the y direction. All peripheries of patch element 1 can be collectively referred to as peripheries 1a-1d.

[0022] C1 is the first center line of the patch element 1. The first center line C1 is parallel to the x direction. The distance between the first perimeter 1a and the first center line C1 is equal to the distance between the third perimeter 1c and the first center line C1. C2 is the second center line of the patch element 1. The second center line C2 is parallel to the y direction. The distance between the second perimeter 1b and the second center line C2 is equal to the distance between the fourth perimeter 1d and the second center line C2. The center C3 is the center of the patch element 1. The center C3 coincides with the intersection of the first center line C1 and the second center line C2.

[0023] Four slots 11 to 14 are formed in patch element 1. Slots 11 to 14 are respectively a first slot 11, a second slot 12, a third slot 13, and a fourth slot 14. Slots 11 to 14 penetrate patch element 1 in the thickness direction.

[0024] The first slot 11 is an L-shaped slot having a first extending portion 11a and a second extending portion 11b. The first extending portion 11a extends in the x direction. The second extending portion 11b extends from the +x side end of the first extending portion 11a to the +y side.

[0025] The second slot 12 is an L-shaped slot having a first extending portion 12a and a second extending portion 12b. The first extending portion 12a extends in the x direction. The second extending portion 12b extends from the -x side end of the first extending portion 12a to the +y side. The second extending portion 12b is located away from the second extending portion 11b of the first slot 11 on the +x side. The second extending portion 12b is formed facing the second extending portion 11b of the first slot 11.

[0026] The third slot 13 is an L-shaped slot having a first extending portion 13a and a second extending portion 13b. The first extending portion 13a extends in the x direction. The second extending portion 13b extends from the +x side end of the first extending portion 13a to the -y side. The first extending portion 13a is located away from the first extending portion 11a of the first slot 11 on the -y side. The first extending portion 13a is formed facing the first extending portion 11a of the first slot 11.

[0027] The fourth slot 14 is an L-shaped slot having a first extending portion 14a and a second extending portion 14b. The first extending portion 14a extends in the x direction. The second extending portion 14b extends from the end of the first extending portion 14a on the -x side to the -y side. The first extending portion 14a is located away from the first extending portion 12a of the second slot 12 on the -y side. The first extending portion 14a is formed opposite the first extending portion 12a of the second slot 12. The second extending portion 14b is located away from the second extending portion 13b of the third slot 13 on the +x side. The second extending portion 14b is formed opposite the second extending portion 13b of the third slot 13.

[0028] In the slots 11 to 14, the length of the first extension portion and the length of the second extension portion may be the same or different. The slots 11 to 14 have, for example, four-fold rotational symmetry (90-degree symmetry) about the center C3. The slots 11 to 14 have, for example, the same shape as each other.

[0029] The first slot 11 is formed in a region (first region 1A) on the +y side of the first center line C1 and on the -x side of the second center line C2. The second slot 12 is formed in a region (second region 1B) on the +y side of the first center line C1 and on the +x side of the second center line C2. The third slot 13 is formed in a region (third region 1C) on the -y side of the first center line C1 and on the -x side of the second center line C2. The fourth slot 14 is formed in a region (fourth region 1D) on the -y side of the first center line C1 and on the +x side of the second center line C2.

[0030] Because patch element 1 has slots 11-14, the path of current flowing through patch element 1 is longer. As a result, the resonant frequency is lower than that of a patch element without slots. If the dimensions of the patch element are determined so that the resonant frequency is the same whether or not there is a slot, the dimensions of the patch element with a slot will be smaller. Therefore, by forming slots 11-14, patch element 1 can be made smaller.

[0031] As shown in Fig. 2, the second dielectric substrate 4 is formed of a dielectric material. In a plan view, the second dielectric substrate 4 has a rectangular shape having a pair of sides parallel to the x direction and a pair of sides parallel to the y direction. The upper surface of the second dielectric substrate 4 is a first main surface 4a. The lower surface of the second dielectric substrate 4 (the surface opposite to the first main surface 4a) is a second main surface 4b. The second dielectric substrate 4 is parallel to the xy plane.

[0032] The second dielectric substrate 4 has, for example, the same shape as the first dielectric substrate 2 in a plan view. The second dielectric substrate 4 is disposed so as to overlap the first dielectric substrate 2 in a plan view. The second dielectric substrate 4 is disposed in parallel with the first dielectric substrate 2.

[0033] 1, the feed circuit 3 is formed on the second main surface 4b of the second dielectric substrate 4 (see FIG. 2). The feed circuit 3 feeds power to the patch element 1. The power supply circuit 3 has a 90-degree hybrid circuit 31. The 90-degree hybrid circuit 31 has first to fourth lines 32 to 35. The first to fourth lines 32 to 35 are each linear. The first to fourth lines 32 to 35 are connected in a rectangular frame shape (rectangular ring shape). The first line 32 and the second line 33 are formed parallel to each other with a gap therebetween. The third line 34 and the fourth line 35 are formed parallel to each other with a gap therebetween.

[0034] In a plan view, the first line 32 is inclined with respect to the x and y directions. More specifically, the first line 32 is inclined from one end 32a to the other end 32b so as to approach the +y side as it approaches the +x side. The second line 33 is inclined with respect to the x and y directions. More specifically, the second line 33 is inclined from one end 33a to the other end 33b so as to approach the +y side as it approaches the +x side.

[0035] In a plan view, one end 32a of first line 32 is located on the -x side of the fourth side (fourth periphery 1d) of patch element 1. One end 32a of first line 32 is located outside patch element 1. The other end 32b of first line 32 is located on the +x side of the fourth side (fourth periphery 1d) of patch element 1. The other end 32b of first line 32 is located inside the periphery of patch element 1 (third region 1C). Therefore, a length portion including the other end 32b of first line 32 is in a position that overlaps with the patch element 1 in a plan view.

[0036] In a plan view, one end 33a of second line 33 is located on the -y side of the third side (third periphery 1c) of patch element 1. One end 33a of second line 33 is located outside patch element 1. The other end 33b of second line 33 is located on the +y side of the third side (third periphery 1c) of patch element 1. The other end 33b of second line 33 is located inside the periphery of patch element 1 (third region 1C). Therefore, a length portion including the other end 33b of second line 33 is in a position that overlaps with patch element 1 in a plan view.

[0037] The third line 34 extends in a direction perpendicular to the first line 32 and the second line 33. The third line 34 connects one end 32a of the first line 32 and one end 33a of the second line 33. In a plan view, the third line 34 is located outside the patch element 1. The fourth line 35 extends in a direction perpendicular to the first line 32 and the second line 33. The fourth line 35 connects the other end 32b of the first line 32 and the other end 33b of the second line 33. In a plan view, the fourth line 35 is located inside the periphery of the patch element 1 (third region 1C).

[0038] A first port 36 is connected to one end 32a of the first line 32. A third port 38 is connected to the other end 32b of the first line 32. A second port 37 is connected to one end 33a of the second line 33. A fourth port 39 is connected to the other end 33b of the second line 33.

[0039] The RF signal input from the first port 36 is equally distributed to the third port 38 and the fourth port 39. The RF signal distributed to the third port 38 and the RF signal distributed to the fourth port 39 have, for example, equal amplitude and a phase difference of 90 degrees. The RF signal input from the second port 37 is equally distributed to the third port 38 and the fourth port 39. The RF signal distributed to the third port 38 and the RF signal distributed to the fourth port 39 have, for example, equal amplitude and a phase difference of 90 degrees. In this way, the 90-degree hybrid circuit 31 distributes the input signal to the two ports 38, 39 with equal amplitude and a phase difference of 90 degrees.

[0040] 2, the pair of feed probes 6 is a first feed probe 61 and a second feed probe 62. Since the antenna 100 includes the two feed probes 61 and 62, it employs a two-point feed method. First feed probe 61 is interposed between third port 38 (see FIG. 1) and patch element 1 , and sends a feed signal (RF signal) from 90 degree hybrid circuit 31 to patch element 1 .

[0041] The first feed probe 61 has a first linking line 63 and a first connecting line 64. The first feed probe 61 is L-shaped with the first linking line 63 and the first connecting line 64 connected perpendicularly to each other. The first linking line 63 is a linear conductor. The first connecting line 64 is a strip conductor.

[0042] The first connecting line 63 starts from the tip of the third port 38 (see Figure 1), extends upward through a through hole 41 formed in the second dielectric substrate 4, and reaches the second main surface 2b of the first dielectric substrate 2. 1, the first connecting line 63 is located so as to overlap with the first center line C1 in a plan view. The first connecting line 63 is located on the -x side of the second center line C2 in a plan view. The first connecting line 63 is located between the first extension portion 11a of the first slot 11 and the first extension portion 13a of the third slot 13 in a plan view.

[0043] As shown in FIG. 2, the first connection line 64 is formed on the second main surface 2b of the first dielectric substrate 2. 1, the first connection line 64 starts from the upper end of the first link line 63 and extends in the +x direction (the direction approaching the center C3) along the first center line C1. The first connection line 64 is located between the first extension portion 11a of the first slot 11 and the first extension portion 13a of the third slot 13 in a plan view. The first connection line 64 is located on the -x side of the second center line C2 in a plan view.

[0044] As shown in FIG. 2, second feed probe 62 is interposed between fourth port 39 (see FIG. 1) and patch element 1 , and sends a feed signal (RF signal) from 90 degree hybrid circuit 31 to patch element 1 .

[0045] The second feed probe 62 has a second linking line 65 and a second connecting line 66. The second feed probe 62 is L-shaped with the second linking line 65 and the second connecting line 66 connected perpendicularly to each other. The second linking line 65 is a linear conductor. The second connecting line 66 is a strip conductor.

[0046] The second connecting line 65 starts from the tip of the fourth port 39 (see Figure 1), extends upward through a through hole 42 formed in the second dielectric substrate 4, and reaches the second main surface 2b of the first dielectric substrate 2. 1, the second connecting line 65 is located so as to overlap with the second center line C2 in a plan view. The second connecting line 65 is located on the -y side of the first center line C1 in a plan view. The second connecting line 65 is located between the second extending portion 13b of the third slot 13 and the second extending portion 14b of the fourth slot 14 in a plan view.

[0047] As shown in FIG. 2, the second connection line 66 is formed on the second main surface 2b of the first dielectric substrate 2. 1, the second connection line 66 starts from the upper end of the second link line 65 and extends in the +y direction (closer to the center C3) along the second center line C2. The second connection line 66 is located between the second extension portion 13b of the third slot 13 and the second extension portion 14b of the fourth slot 14 in a plan view. The second connection line 66 is located on the -y side of the first center line C1 in a plan view.

[0048] 2, the ground conductor plate 5 is formed on the first main surface 4a of the second dielectric substrate 4. The ground conductor plate 5 is formed, for example, over almost the entire area of ​​the first main surface 4a. The ground conductor plate 5 is formed with an insertion hole 51 through which the first connecting line 63 is inserted and an insertion hole 52 through which the second connecting line 65 is inserted. Therefore, the first connecting line 63 and the second connecting line 65 are not in contact with the ground conductor plate 5.

[0049] The first dielectric substrate 2 and the second dielectric substrate 4 are disposed at a distance in the vertical direction (thickness direction of the dielectric substrates 2, 4: z direction). The first dielectric substrate 2 and the ground conductor plate 5 are vertically separated. An air layer is formed between the first dielectric substrate 2 and the ground conductor plate 5. Such a structure in which the two dielectric substrates are separated from each other is called a "suspended structure." This structure can reduce the effective relative dielectric constant of the dielectric substrate and increase the electrical thickness of the dielectric substrate relative to the wavelength.

[0050] By adopting a suspended structure, the antenna 100 can operate in the 860 to 930 MHz band (relative bandwidth to center frequency 895 MHz: approximately 10%), which includes the 860 MHz and 920 MHz frequency bands used in the satellite IoT platform (satellite IoT-PF).

[0051] When back-coupled feeding is performed on a patch antenna with a suspended structure, the electrical dimensions of the feeding probe become large, and there is a possibility that matching cannot be obtained due to the effect of the parasitic inductance of the feeding probe. In contrast, antenna 100 of this embodiment achieves wideband matching by compensating for the effect of parasitic inductance using L-shaped feed probes 61 and 62. That is, in antenna 100, L-shaped feed probes 61 and 62 are used to perform back-coupled feeding from the lower (back) surface side of patch element 1, thereby making it possible to broaden the antenna operating band.

[0052] In the antenna 100, two signals with equal amplitude and a phase difference of 90 degrees are obtained using a feeding circuit 3 having a 90-degree hybrid circuit 31, and these signals are supplied to L-shaped feeding probes 61 and 62, thereby achieving circularly polarized excitation. Therefore, the antenna 100 is a multi-frequency circularly polarized antenna.

[0053] As shown in Figure 1, when one of the first port 36 and the second port 37 of the 90-degree hybrid circuit 31 is excited and the other is connected to a matching load, the main polarization component in the main beam direction is right-handed polarized. The cross polarization component is left-handed polarized. By interchanging the excitation port and the port connected to the matching load, the rotation direction of the main polarization can be reversed from the above-mentioned direction.

[0054] In antenna 100 of the present embodiment, a portion of 90-degree hybrid circuit 31 is formed in a position that overlaps with patch element 1 in a plan view. Therefore, in antenna 100, the area occupied by 90-degree hybrid circuit 31 and patch element 1 in a plan view can be made smaller than in a case where the patch element and the 90-degree hybrid circuit are formed at different planar positions. This allows antenna 100 to be made smaller.

[0055] The antenna 100 employs a structure (suspended structure) in which two dielectric substrates are spaced apart from each other, thereby enabling it to achieve an operating band of 860 to 930 MHz, which includes the 860 MHz and 920 MHz frequency bands used in the satellite IoT-PF, for example.

[0056] The frequency characteristics of the axial ratio and the actual gain in the main beam direction (+z direction) were evaluated by electromagnetic field analysis based on the finite element method. Fig. 3 is a plan view of the antenna 100. Fig. 4 is a side cross-sectional view that typically shows the structure of the antenna 100. Figs. 3 and 4 show the dimensions of the antenna 100 used in the simulation. The dimensions and characteristics of the antenna 100 are as follows: L s : 140mm, L p :100mm, S:30mm, L: f : 6.0mm, W f :2.0mm, d:1.2mm, L a : 42mm, W a :2.0mm, P a :4.0mm, h:0.8mm, W 0 : 1.8mm, W 1 : 3.0mm, L 1 : 50mm, L 2 :54mm, ε r :3.4

[0057] L s are the dimensions of the first dielectric substrate 2 and the second dielectric substrate 4 in the x and y directions. L p are the dimensions of patch element 1 in the x and y directions. S is the distance between first dielectric substrate 2 and ground plane 5. Lf is the length of the first connecting line 64 and the second connecting line 66. W f is the width of the first connecting line 64 and the second connecting line 66. d is the width of the first connecting line 63 and the second connecting line 65. L a is the length of the first extension portion and the second extension portion of the slots 11 to 14. a is the width of the first and second extending portions of the slots 11 to 14. a is the distance between the slots 11 to 14 and the center lines C1 and C2. h is the thickness of the first dielectric substrate 2 and the second dielectric substrate 4. W 0 is the width of the third line 34, the fourth line 35, the third port 38 and the fourth port 39. W 1 is the width of the first line 32 and the second line 33. 1 is the length of the first line 32 and the second line 33. 2 is the length of the third line 34 and the fourth line 35. ε r is the relative dielectric constant of first dielectric substrate 2 and second dielectric substrate 4. Slots 11 to 14 have the same shape. The center of patch element 1 coincides with the center of first dielectric substrate 2 in a plan view.

[0058] P f is the distance from the center C3 of the patch element 1 to the interconnection lines 63 and 65 in a plan view. f is the distance from the center C3 to the center of the connecting lines 63 and 65 in a plan view. f was set to 28mm~40mm.

[0059] Fig. 5 is a diagram showing a simulation result of the frequency characteristic of the axial ratio in the main beam direction (+z direction). Fig. 6 is a diagram showing a simulation result of the frequency characteristic of the actual gain in the main beam direction (+z direction).

[0060] From Figs. 5 and 6, P f It can be seen that the axial ratio and actual gain change depending on the distance (the distance from center C3 of patch element 1 in a plan view to connecting lines 63 and 65).

[0061] From Figure 5, P f Set appropriately (e.g., P f It can be seen that by setting the antenna diameter to 28mm to 36mm, the axial ratio, which is the operating standard for circularly polarized wave operation, can be made small (for example, 3dB or less) in the operating band of 860 to 930MHz (design frequency band). This design frequency band (860 to 930MHz) includes the 860MHz and 920MHz frequency bands used by the satellite IoT-PF.

[0062] From Figure 6, P f Set appropriately (e.g., P f It can be seen that if the distance between the optical fiber and the casing is set to 28 mm to 36 mm, the operating gain can be increased in the operating band of 860 to 930 MHz.

[0063] The wavelength at the center frequency of 860 to 930 MHz (895 MHz) is 335 mm. Therefore, the appropriate positions of feed probes 61, 62 (connection lines 63, 65) are positions that are 0.083 to 0.107 times the wavelength at the center frequency of the design frequency band from center C3 of patch element 1 toward the periphery in a planar view. In other words, the distance from center C3 of patch element 1 to feed probes 61, 62 (connection lines 63, 65) in a planar view is preferably 0.083 to 0.107 times the wavelength at the center frequency of the design frequency band.

[0064] Second embodiment 7 is a plan view of an antenna 200 according to the second embodiment. Components common to the other embodiments are given the same reference numerals and descriptions thereof will be omitted. As shown in FIG. 7, the antenna 200 differs from the antenna 100 of the first embodiment in that it includes a feed circuit 203 instead of the feed circuit 3.

[0065] The power supply circuit 203 has a 90-degree hybrid circuit 231. The 90-degree hybrid circuit 231 has first to fourth lines 232 to 235. The first to fourth lines 232 to 235 are each linear. The first to fourth lines 232 to 235 are connected in a rectangular frame shape (rectangular ring shape). The first line 232 and the second line 233 are formed parallel to each other with a gap therebetween. The third line 234 and the fourth line 235 are formed parallel to each other with a gap therebetween.

[0066] In a plan view, the first line 232 is inclined with respect to the x and y directions. More specifically, the first line 232 is inclined from one end 232a to the other end 232b so as to approach the -y side as it approaches the -x side. The second line 233 is inclined with respect to the x and y directions. More specifically, the second line 233 is inclined from one end 233a to the other end 233b so as to approach the -y side as it approaches the -x side.

[0067] In a plan view, one end 232a of first line 232 is located inside (second region 1B) the periphery of patch element 1. The other end 232b of first line 232 is located inside (first region 1A) the periphery of patch element 1. First line 232 is located so as to overlap patch element 1 over its entire length in a plan view.

[0068] In plan view, one end 233a of second line 233 is located inside the periphery (second region 1B) of patch element 1. The other end 233b of second line 233 is located inside the periphery (fourth region 1D) of patch element 1. Second line 233 is located so as to overlap patch element 1 over its entire length in plan view.

[0069] Third line 234 extends in a direction perpendicular to first line 232 and second line 233. Third line 234 connects one end 232a of first line 232 and one end 233a of second line 233. Third line 234 is located inside the periphery of patch element 1. Third line 234 is located so as to overlap patch element 1 over its entire length in a plan view.

[0070] Fourth line 235 extends in a direction perpendicular to first line 232 and second line 233. Fourth line 235 connects the other end 232b of first line 232 and the other end 233b of second line 233. Fourth line 235 is located inside the periphery of patch element 1. Fourth line 235 is located so as to overlap with patch element 1 over its entire length in a plan view.

[0071] A first port 36 is connected to one end 232a of the first line 232. A third port 38 is connected to the other end 232b of the first line 232. A second port 37 is connected to one end 233a of the second line 233. A fourth port 39 is connected to the other end 233b of the third line 234.

[0072] In antenna 200 of the present embodiment, 90-degree hybrid circuit 231 is formed at a position where it entirely overlaps with patch element 1 in a plan view. This allows antenna 200 to reduce the area occupied by 90-degree hybrid circuit 231 and patch element 1 in a plan view. This allows antenna 200 to be made smaller in size. In antenna 200, 90-degree hybrid circuit 231 does not protrude outward from patch element 1 in a plan view, and therefore there are fewer restrictions on the placement of 90-degree hybrid circuit 231. This is advantageous in terms of miniaturizing antenna 200.

[0073] In antenna 100 shown in FIG. 1, patch element 1 is formed on first principal surface 2a of first dielectric substrate 2, but patch element 1 may also be formed inside first dielectric substrate 2.

[0074] In the antenna 100, the second dielectric substrate 4 is disposed so as to overlap with the first dielectric substrate 2 in a plan view, but the second dielectric substrate 4 may be disposed so that only a partial area thereof in a plan view overlaps with the first dielectric substrate 2. In other words, the second dielectric substrate 4 may be disposed so that at least a portion thereof overlaps with the first dielectric substrate 2 in a plan view.

[0075] In the antenna 100, the first feed probe 61 has the first linking line 63 and the first connection line 64 connected orthogonally to each other (see FIG. 2), but the extending directions of the first linking line and the first connection line need only intersect with each other. In the second feed probe 62, the extending directions of the second linking line and the second connection line need only intersect with each other. The number of feed probes may be any number equal to or greater than two.

[0076] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0077] 100, 200...antenna, 2...first dielectric substrate, 3,203...feed circuit, 4...second dielectric substrate, 31,231...90 degree hybrid circuit, 6...feed probe, C3...center of patch element

Claims

1. A patch element; a first dielectric substrate on which the patch element is formed; a feeding circuit including a 90-degree hybrid circuit and feeding the patch element; a second dielectric substrate on which the 90-degree hybrid circuit is formed; a pair of feed probes for transmitting a feed signal from the 90-degree hybrid circuit to the patch element; Equipped with The first dielectric substrate and the second dielectric substrate are disposed at an interval in a thickness direction, When viewed from a direction perpendicular to the patch element, at least a portion of the 90-degree hybrid circuit is formed at a position overlapping the patch element. antenna.

2. the 90-degree hybrid circuit is formed at a position where the entirety of the hybrid circuit overlaps with the patch element; 2. The antenna of claim 1.

3. In a plan view, the distance from the center of the patch element to the feed probe is 0.083 to 0.107 times the wavelength at the center frequency of the design frequency band.

3. An antenna as claimed in claim 1 or 2.

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