Microstrip antenna

Abstract

Provided is a microstrip antenna that can be downsized. The microstrip antenna includes: a substrate made of a dielectric; a ground electrode provided on a first surface of the substrate; an antenna element having a plurality of radiating elements provided on a second surface of the substrate opposite the first surface and extending in parallel to each other, and a connecting element provided on the second surface and extending in a direction crossing the plurality of radiating elements to connect the plurality of radiating elements; a power supply line having a first end portion connected to a portion of a radiating element located at an end portion in a plan view among the plurality of radiating elements, the portion being located on an extension of the connecting element, and a second end portion provided on a side surface of the substrate between the first surface and the second surface and supplied with power; and a connection line having a section provided on the side surface of the substrate along the power supply line to connect the radiating element located at the end portion and the ground electrode.

Description

Technical Field

[0001] This invention relates to microstrip antennas. Background Technology

[0002] Conventionally, there is an antenna device comprising: a dielectric substrate; a grounding conductor film disposed on the lower surface of the dielectric substrate; a radiating conductor film disposed on the upper surface of the dielectric substrate; and a connecting conductor film disposed on the side of the dielectric substrate and connecting the grounding conductor film and the radiating conductor film (for example, see Patent Document 1).

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: JP Japanese Patent Application Publication No. 11-112221 Summary of the Invention

[0006] -The problem the invention aims to solve-

[0007] Since the wavelength on a dielectric substrate varies depending on the relative permittivity of the dielectric substrate, the larger the relative permittivity, the shorter the wavelength. Therefore, if a dielectric substrate with a large relative permittivity is used, the antenna device can be miniaturized.

[0008] The existing antenna device is a single-sided short-circuit microstrip antenna using a dielectric ceramic substrate with a relative permittivity of 38, resonating at a frequency of 3.8 GHz. The dimensions of the dielectric substrate are 10 mm × 8 mm × 4 mm, and the free space wavelength λ0 at 3.8 GHz is approximately 77 mm. If the free space wavelength λ0 is characterized by the dimensions of the dielectric substrate, it is approximately 0.13λ0 × 0.1λ0 × 0.05λ0.

[0009] However, in the field of RFID (Radio Frequency Identifier) ​​tags using the 920MHz frequency band, due to the requirement to attach RFID tags to small objects, a size of 0.1cm is sought. 3 ~0.2cm 3 A degree of antenna device.

[0010] If the volume is characterized by size, it would be approximately 7mm × approximately 7mm × approximately 2mm. If the volume is characterized by the free-space wavelength λ0 of 920MHz, it would be approximately 0.02λ0 × 0.02λ0 × 0.006λ0. Therefore, in existing single-sided short-circuited microstrip antennas, it is impossible to achieve communication within 0.1cm in the 920MHz band. 3 ~0.2cm 3 The volume of degree.

[0011] Therefore, the goal is to provide a microstrip antenna that can be miniaturized.

[0012] -Methods for solving problems-

[0013] A microstrip antenna according to an embodiment of the present invention comprises: a substrate made of dielectric material; a ground electrode disposed on a first surface of the substrate; an antenna element having a plurality of radiating elements and a connecting element, wherein the plurality of radiating elements are disposed on a second surface of the substrate opposite to the first surface and extend parallel to each other, and the connecting element is disposed on the second surface and extends in a direction intersecting the plurality of radiating elements to connect the plurality of radiating elements; a power supply line having a first end and a second end, wherein the first end is connected to a portion of the radiating element located at the end in view of top view, which is located on an extension of the connecting element, and the second end is disposed on a side surface of the substrate between the first surface and the second surface and is powered; and a connecting line having a section disposed on the side surface of the substrate along the power supply line to connect the radiating element located at the end and the ground electrode.

[0014] -Invention Effects-

[0015] It can provide microstrip antennas that can be miniaturized. Attached Figure Description

[0016] Figure 1 This is a diagram representing microstrip antenna 100.

[0017] Figure 2 This is a diagram representing microstrip antenna 100.

[0018] Figure 3 This is a diagram representing microstrip antenna 100.

[0019] Figure 4 This is a diagram representing microstrip antenna 100.

[0020] Figure 5 This is a graph showing the resonant frequency and the change in VSWR when the lengths La, Lb, and Lc are varied in the microstrip antenna 100.

[0021] Figure 6 It is a diagram representing the simulation model.

[0022] Figure 7 This is a graph representing the frequency characteristics of the VSWR.

[0023] Figure 8 It is a diagram representing radiation characteristics.

[0024] Figure 9 It is a diagram representing the simulation model.

[0025] Figure 10 This is a graph representing the frequency characteristics of the VSWR.

[0026] Figure 11 It is a diagram representing radiation characteristics.

[0027] Figure 12 This is a diagram showing the microstrip antenna 100M1 of the first modified embodiment.

[0028] Figure 13 This is a diagram showing the microstrip antenna 100M1 of the first modified embodiment.

[0029] Figure 14 This is a diagram showing the microstrip antenna 100M2 of the second variation of the embodiment.

[0030] Figure 15 This is a diagram showing the microstrip antenna 100M2 of the second variation of the embodiment. Detailed Implementation

[0031] The following describes an embodiment of the microstrip antenna using the present invention.

[0032] <Implementation Method>

[0033] The following describes an embodiment of the microstrip antenna using the present invention. The XYZ coordinate system will be defined for explanation. The directions parallel to the X-axis (X direction), parallel to the Y-axis (Y direction), and parallel to the Z-axis (Z direction) are orthogonal to each other. Furthermore, for ease of explanation, the -Z direction side will sometimes be referred to as the lower side or lower, and the +Z direction side as the upper side or upper. Also, "top view" refers to viewing from the XY plane. Furthermore, the length, thickness, etc., of each part will sometimes be exaggerated for ease of understanding of the structure. Furthermore, the terms parallel, up / down, and right angle are allowed to deviate to a degree without diminishing the effectiveness of the embodiment.

[0034] Figures 1 to 4 This is a diagram representing microstrip antenna 100. Figure 1 This is a three-dimensional view of the microstrip antenna 100 from the top. Figure 2 This is a three-dimensional view of the microstrip antenna 100 from the bottom. Figure 3 It is a top view. Figure 4 This is a side view of the microstrip antenna 100 from the +X direction.

[0035] The microstrip antenna 100 includes a substrate 10, a ground electrode 110, an antenna element 120, a power supply line 130, and a connection line 140. The microstrip antenna 100 is envisioned for use in an RFID tag as an example. Hereinafter, as an example, the communication mode in the 920MHz band will be described.

[0036] The purpose of this embodiment is to provide a miniaturized microstrip antenna, and more specifically, to provide a surface-mount microstrip antenna 100 that is smaller than existing microstrip antennas, with a side width of approximately 0.02λ0 and a thickness of approximately 0.006λ0. λ0 is the wavelength of a radio wave in the 920MHz band in free space.

[0037] The substrate 10 is made of dielectric material, for example, a high-dielectric-constant ceramic with a relative permittivity εr of 93. High-dielectric-constant ceramics, for example, can be made primarily of barium oxide, titanium oxide, neodymium oxide, cerium oxide, samarium oxide, or bismuth oxide. The substrate 10 is, for example, a rectangular parallelepiped-shaped substrate that appears square when viewed from above, and for example, it is 7mm (X direction) × 7mm (Y direction) × 2mm (Z direction). The lower surface 10A (the surface on the -Z direction side) of the substrate 10 is, for example, a first surface, and the upper surface 10B (the surface on the +Z direction side) of the substrate 10 is, for example, a second surface on the opposite side of the lower surface 10A, which is, for example, the first surface.

[0038] The ground electrode 110, antenna element 120, power supply line 130, and connection line 140 can be formed, for example, by printing conductive paste such as silver paste or copper paste on the lower surface 10A, upper surface 10B, and side surface 10C of the substrate 10 and then firing it. The side surface 10C is located between the lower surface 10A (as an example of a first surface) and the upper surface 10B (as an example of a second surface), connecting the lower surface 10A and the upper surface 10B. Here, as an example, the form formed with silver paste will be described. The ground electrode 110, antenna element 120, power supply line 130, and connection line 140 have the same thickness, for example, about 10 μm to 15 μm.

[0039] A grounding electrode 110 is disposed on the lower surface 10A of the substrate 10. The lengths of the grounding electrode 110 in the X and Y directions are equal for example.

[0040] Antenna element 120 includes: four radiating elements 120A extending in the Y direction; and three connecting elements 120B extending in the X direction. Figure 1 In order to make the structure easier to understand, the boundary between the four radiating elements 120A and the three connecting elements 120B is shown with dashed lines.

[0041] Four radiating elements 120A are parallel to each other and arranged at equal intervals in the X direction. Three connecting elements 120B are disposed between the four radiating elements 120A and connect the central portions 120A1 of the length of the four radiating elements 120A in the Y direction. The central portion 120A1 is the part containing the center of the length of the radiating elements 120A in the Y direction. The three connecting elements 120B are located on the same straight line and extend in the X direction that intersects with the four radiating elements 120A.

[0042] Antenna element 120 can be viewed as a structure with one connecting element extending in the X direction on the +Y direction side and eight radiating elements connected on the -Y direction side. Here, it is described as a structure with four radiating elements 120A extending in the Y direction and three connecting elements 120B extending in the X direction.

[0043] The power supply line 130 has: an end portion 131 connected to the central portion 120A1 in the Y direction of one of the four radiating elements 120A located on the +X direction side; and an end portion 132 located at the lower end of the side surface 10C on the +X direction side of the substrate 10. End portion 131 is an example of a first end portion, and end portion 132 is an example of a second end portion. The central portion 120A1 of the radiating element 120A located on the +X direction side is located on the extension of the connecting element 120B and is the portion connected to end portion 131.

[0044] The power supply line 130 extends along the surface of the upper surface 10B and the side surface 10C of the substrate 10 between end 131 and end 132. End 132 is a power supply section that connects to and supplies power to the core wires of a coaxial cable (not shown). The shield of this coaxial cable can be connected to the ground electrode 110.

[0045] Two connecting lines 140 are located on the +Y and -Y direction sides of the power supply line 130, and are arranged at equal intervals with the power supply line 130. The power supply line 130 and the two connecting lines 140 constitute a coplanar line 150. The coplanar line 150 is suitable for the transmission of high-frequency signals.

[0046] Each connection line 140 has an end portion 141 connected to the +X direction side end of one of the four radiating elements 120A located at the +X direction side; and an end portion 142 connected to the +X direction side end of the ground electrode 110. The connection line 140 extends between the end portion 141 and the end portion 142 along the surfaces of the lower surface 10A, the upper surface 10B, and the side surface 10C of the substrate 10. The section of the connection line 140 located on the side surface 10C is a section located on the side surface 10C of the substrate 10 along the power supply line 130.

[0047] The end 141 of the connecting line 140 on the +Y direction side is connected to the central portion 120A1 of a radiating element 120A located on the +X direction side, which is closer to the +Y direction side than the central portion 120A1. The end 141 of the connecting line 140 on the -Y direction side is connected to the central portion 120A1 of a radiating element 120A located on the +X direction side, which is closer to the -Y direction side than the central portion 120A1.

[0048] like Figure 3 As shown, the overall length of the antenna element 120 of such a microstrip antenna 100 in the Y direction is La, and the length in the X direction is Ld. Furthermore, the length of the section of the radiating element 120A that protrudes further in the Y direction than the connecting element 120B is Lb, and the length between the center of the width of the power supply line 130 in the Y direction and the connecting line 140 is Lc. As an example, lengths La and Ld can be equal or different.

[0049] Furthermore, the length (width) in the X direction of the two radiating elements 120A located at the +X direction end and the -X direction end is Le, and the length (width) in the X direction of the two radiating elements 120A located at the center side is Lg. Additionally, the length in the X direction of the three connecting elements 120B is Lf. The length Lf corresponds to the X-direction spacing of the four radiating elements 120A. Here, as an example, the length Le is longer than the length Lg, but they can also be the same, or the length Le can be shorter than the length Lg.

[0050] Furthermore, since the antenna element 120 is two comb-shaped teeth, it has a notch (cutout) 120C between the radiating elements 120A. The length Lb is the length of the notch 120C.

[0051] The microstrip antenna 100 incorporating such antenna element 120 can achieve a lower resonant frequency than a microstrip antenna containing patch electrodes of length La×Ld. In other words, at the same resonant frequency, a more miniaturized microstrip antenna 100 can be achieved than a microstrip antenna containing patch electrodes of length La×Ld. This is because the path of high-frequency current can be effectively lengthened.

[0052] Generally, in microstrip antennas containing ceramic substrates, patch electrodes, ground electrodes, etc., are formed by printing conductive paste such as silver paste or copper paste and then firing them. Since ceramic substrates sometimes deviate in relative permittivity, various printing plates with slightly different dimensions are prepared to accommodate these deviations. These plates are used to test the printing of conductive paste, and the plate that yields the desired resonant frequency and input impedance is selected for mass production.

[0053] Here, since the resonant frequency and input impedance depend on the size of the patch electrode, it is difficult to independently determine the resonant frequency and input impedance in a microstrip antenna containing patch electrodes.

[0054] In this embodiment, a microstrip antenna 100 is provided that can determine the resonant frequency and input impedance substantially independently. With a relative permittivity εr of the substrate 10 of 93, a 0.1 cm... 3 The dimensions of the substrate are approximately 7mm × approximately 7mm × approximately 2mm. Therefore, the dimensions of the substrate 10, as described above, are, for example, 7mm × 7mm × 2mm.

[0055] In this case, Figure 3 The lengths La, Lb, Lc, and Ld shown are, for example, La = Ld = 6 mm, Lb = 2.4 mm, and Lc = 0.8 mm. The surface-mount microstrip antenna 100 with these lengths La, Lb, Lc, and Ld resonates at approximately 920 MHz, and the input impedance of the end 132 (power supply section) of the power supply line 130 becomes approximately 50 Ω.

[0056] Figure 5 This is a graph showing the resonant frequency and the change in VSWR (Voltage Standing Wave Ratio) when the lengths La, Lb, and Lc of the microstrip antenna 100 are varied. Figure 5 The characteristics shown are simulation results obtained in electromagnetic field simulation.

[0057] exist Figure 5 (A) shows the change in resonant frequency Δf0 and the change in VSWR relative to the change in length La. Figure 5 (B) shows the change in resonant frequency Δf0 and the change in VSWR relative to the change in length Lb. Figure 5 Figure (C) shows the change in resonant frequency Δf0 and the change in VSWR relative to the change in length Lc ΔLc. Here, when the length La changes, the lengths Lb and Lc are constant. Similarly, when the length Lb changes, the lengths La and Lc are constant, and when the length Lc changes, the lengths La and Lb are constant.

[0058] like Figure 5 (A) and Figure 5 As shown in (B), it can be seen that when the length La or the length Lb is varied, the VSWR remains almost unchanged, while the resonant frequency changes significantly. Furthermore, from... Figure 5 As can be seen from (C), VSWR changes significantly when the length Lc is varied.

[0059] Therefore, the microstrip antenna 100 can be designed very easily when printing various ground electrodes 110, antenna elements 120, power supply lines 130, and connection lines 140.

[0060] Furthermore, if the resonant frequency of the surface-mount microstrip antenna 100 deviates from the desired resonant frequency, adjustments are generally made to align it with the resonant frequency.

[0061] If the resonant frequency of the fabricated surface-mount microstrip antenna 100 is lower than the desired resonant frequency, the length La can be shortened by cutting the ends of the radiating element 120A in the +Y and -Y directions. If the length La is shortened, then as from... Figure 5 As is known in (A), it can increase the resonant frequency.

[0062] On the other hand, if the resonant frequency of the surface-mount microstrip antenna 100 is higher than the desired resonant frequency, the connecting element 120B can be made thinner by further reducing the ends of the connecting element 120B on the +Y and -Y directions towards the center in the Y direction, thereby extending the length Lb of the notch 120C. By extending the length Lb, such as from... Figure 5 As is known in (B), it can reduce the resonant frequency.

[0063] Figure 6 It is a diagram representing the simulation model. Figure 6 The microstrip antenna 100A shown in (A) is Figure 1 The simulation model of the microstrip antenna 100 shown. Figure 6 The microstrip antenna 100B shown in (B) is a simulation model in which the radiating element 120A of the antenna element 120 consists of 3 roots. Figure 6 The microstrip antenna 100C shown in (C) is a simulation model in which the radiating element 120A of the antenna element 120 consists of two roots.

[0064] Furthermore, simulations were performed with the microstrip antennas 100A to 100C mounted on the upper surface of the substrate 20. The substrate 20 has power supply wiring 21 on its upper surface and ground layers 22 located on three sides of the wiring 21 when viewed from above. As an example, the wiring 21 is connected to the end 132 (power supply section) of the power supply line 130, and the ground layers 22 are insulated from the ground electrode 110.

[0065] As an example, in microstrip antenna 100A, the length La is 6 mm, the length Lb is 2.43 mm, the length Lc is 0.82 mm, and the length Ld is 6 mm. In microstrip antenna 100B, the length La is 6 mm, the length Lb is 2.58 mm, the length Lc is 0.82 mm, and the length Ld is 6 mm. In microstrip antenna 100C, the length La is 6 mm, the length Lb is 2.82 mm, the length Lc is 1.1 mm, and the length Ld is 6 mm.

[0066] Figure 7 This is a graph representing the frequency response of VSWR. Figure 7 The frequency characteristics of VSWR obtained in the simulation models of microstrip antennas 100A to 100C are shown in (A) to (C), respectively.

[0067] like Figure 7 As shown in (A) to (C), the bandwidth for a VSWR of 2 is 2.6 MHz in microstrip antenna 100A, 2.4 MHz in microstrip antenna 100B, and 3.0 MHz in microstrip antenna 100C. It can be seen that although there are some differences in bandwidth, the frequency characteristics of the VSWR do not change significantly depending on the number of radiating elements 120A.

[0068] Figure 8 It is a graph representing radiation characteristics. In Figure 8 Figures (A) to (C) show the radiation characteristics obtained in the simulation models of microstrip antennas 100A to 100C, respectively. Figure 8 In (A) to (C), from left to right, the 3D pattern, the pattern in the ZX plane, and the pattern in the ZY plane are shown.

[0069] like Figure 8 As shown in (A) to (C), the 3D pattern, the pattern in the ZX plane, and the pattern in the ZY plane exhibit the same tendency in both gain and directivity. The gain in the +Z direction is -21.7 dBi in microstrip antenna 100A, -22.1 dBi in microstrip antenna 100B, and -22.4 dBi in microstrip antenna 100C. It can be seen that there is no significant change in gain and directivity depending on the number of radiating elements 120A.

[0070] Figure 9 It is a diagram representing the simulation model. Figure 9 The microstrip antenna 100A shown in (A) is Figure 1 The simulation model of the microstrip antenna 100 shown. Figure 9 The microstrip antenna 100D shown in (B) is a simulation model with the connecting line 140 consisting of a single wire. That is, the microstrip antenna 100D is a structure without coplanar lines. Figure 9The microstrip antenna 50 shown in (C) is a simulation model that replaces antenna element 120 by including patch electrodes and making the connecting line 140 a single line. That is, the microstrip antenna 50 is a comparative simulation model that includes patch electrodes but does not include coplanar lines.

[0071] Furthermore, simulations were performed with microstrip antennas 100A, 100D, and 50 mounted on the upper surface of substrate 20. Substrate 20 has power supply wiring 21 on its upper surface and ground layers 22 located on three sides of wiring 21 when viewed from above. As an example, wiring 21 is connected to the end 132 (power supply section) of power supply line 130, and ground layers 22 are insulated from ground electrode 110.

[0072] As an example, in microstrip antenna 100A, the length La is 6 mm, the length Lb is 2.43 mm, the length Lc is 0.82 mm, and the length Ld is 6 mm. In microstrip antenna 100D, the length La is 6 mm, the length Lb is 1.8 mm, the length Lc is 0.5 mm, and the length Ld is 6 mm. In microstrip antenna 50, the length La is 4.95 mm, the length Lb is 0 mm, the length Lc is 0.5 mm, and the length Ld is 4.95 mm.

[0073] Figure 10 This is a graph representing the frequency response of VSWR. Figure 10 The frequency characteristics of VSWR obtained in the simulation models of microstrip antennas 100A, 100D, and 50 are shown in (A) to (C), respectively.

[0074] like Figure 10 As shown in (A) to (C), the bandwidth for a VSWR of 2 is 2.6 MHz in microstrip antenna 100A, but the minimum VSWR is approximately 4 in microstrip antenna 100D and approximately 5.8 in microstrip antenna 50. It can be seen that there is a difference in the frequency characteristics of VSWR between coplanar lines 150 and non-coplanar lines 150. Specifically, it can be confirmed that the frequency characteristics of VSWR in microstrip antenna 100D are better than those in microstrip antenna 50.

[0075] Figure 11 It is a graph representing radiation characteristics. In Figure 11 Figures (A) to (C) show the radiation characteristics obtained from simulation models of microstrip antennas 100A, 100D, and 50, respectively. Figure 11 In (A) to (C), from left to right, the 3D pattern, the pattern in the ZX plane, and the pattern in the ZY plane are shown.

[0076] like Figure 11 As shown in (A) to (C), it can be known that Figure 11The 3D patterns shown in (A) to (C), the patterns in the ZX plane, and the patterns in the ZY plane differ when they are coplanar lines 150 and when they are not. The gain in the +Z direction is -21.7 dBi in microstrip antenna 100A, -21.8 dBi in microstrip antenna 100D, and -25.2 dBi in microstrip antenna 100C.

[0077] In the microstrip antenna 100A, which includes coplanar lines 150, the polarized wave is located on the X-axis because the radiation characteristics are symmetrical with respect to the X-axis. In contrast, in the microstrip antennas 100D and 50, the polarized wave deviates from the X-axis.

[0078] Furthermore, in the microstrip antenna 100A that includes the coplanar line 150, it is easy to achieve a 50Ω matching of the input impedance in the power supply section, thus suppressing radiation from the power supply section. In contrast, it can be confirmed that in the microstrip antennas 100D and 50 that do not contain the coplanar line 150, it is difficult to achieve a 50Ω matching of the input impedance in the power supply section.

[0079] Furthermore, it can be confirmed that in the microstrip antenna 100A containing the coplanar line 150, the direction of maximum gain is the zenith (+Z direction), but in the microstrip antennas 100D and 50, the direction of maximum gain deviates.

[0080] As described above, an antenna element 120 with four radiating elements 120A and three connecting elements 120B is provided on a high-dielectric-constant ceramic substrate 10 with a relative permittivity εr of 93. It is connected to a ground electrode 110 via a coplanar line 150, thereby providing a surface-mount microstrip antenna 100 with an X and Y axis of approximately 0.02λ0 and a thickness of approximately 0.006λ0. The volume of this surface-mount microstrip antenna 100 is approximately 0.1 cm². 3 .

[0081] Therefore, a miniaturized microstrip antenna 100 can be provided.

[0082] Since the connecting element 120B connects the central portion 120A1 of the extension direction of the plurality of radiating elements 120A, the radiating elements 120A are symmetrically arranged with respect to the connecting element 120B, and symmetrical radiation characteristics can be obtained in the extension direction of the radiating elements 120A.

[0083] Furthermore, since the lengths of the multiple radiating elements 120A are equal in the extension direction, uniform radiation characteristics (uniform radiation characteristics on the plane) can be obtained in both the extension direction of the radiating element 120A and the extension direction of the connecting element 120B.

[0084] Furthermore, since the extension directions of the multiple radiating elements 120A and the extension directions of the connecting element 120B are orthogonal when viewed from above, more uniform radiation characteristics (more uniform radiation characteristics on the plane) can be obtained in the extension directions of the radiating elements 120A and the connecting element 120B.

[0085] Furthermore, since the end 131 of the power supply line 130 and the end 141 connected to the radiating element 120A located on the +X direction side of the connecting line 140 are provided on the upper surface 10B of the substrate 10, the connection between the radiating element 120A and the power supply line 130 and the connecting line 140 is easy to manufacture.

[0086] Furthermore, since the connecting line 140 consists of two connecting lines 140 that extend from the power supply line 130 and together with the power supply line 130 form a coplanar line 150, it is easy to match the input impedance of the power supply line 130, and the input impedance of the power supply line 130 can be set to 50Ω.

[0087] Furthermore, the above description illustrates that the microstrip antenna 100 includes two connecting lines 140, which, together with the power supply line 130, form a coplanar line 150. However, it can also be configured as follows: Figure 9 As shown in (B) the microstrip antenna 100D, the connecting line 140 is a single line. Since the input impedance of the end 132 (power supply section) of the power supply line 130 deviates from 50Ω, the radiation characteristics are degraded, but such a structure is also possible in cases where there are structural constraints, for example.

[0088] Furthermore, the above describes a microstrip antenna 100 that includes antenna element 120 resonating at 920MHz, but the resonant frequency is not limited to 920MHz.

[0089] Furthermore, the above describes the configuration of antenna element 120 comprising four radiating elements 120A. However, as long as there are two or more radiating elements 120A, the number of elements 120A is acceptable. For example, if there are three radiating elements 120A, it becomes... Figure 6 The structure of the microstrip antenna 100B shown in (B) becomes, if the radiating element 120A consists of two elements, then it becomes Figure 6 The structure is similar to that of the microstrip antenna 100C shown in (C).

[0090] In addition, the microstrip antenna 100 can be transformed. Figures 12 to 15 The structure shown. Figure 12 as well as Figure 13 This is a diagram showing the microstrip antenna 100M1 of the first modified embodiment.

[0091] The microstrip antenna 100M1 has a structure in which slits 121A and 122A are added to the front end of the radiating element 120A and slits 121B and 122B are added to the connecting element 120B. Slits 121A and 122A are elongated openings provided in the radiating element 120A, and slits 121B and 122B are elongated openings provided in the connecting element 120B.

[0092] Slits 121A and 122A are located at the ends of the radiating element 120A on the +Y direction side and the -Y direction side, respectively. Slits 121A and 122A are arranged in this order starting from the front end side of the radiating element 120A in the Y direction. Slits 121A and 122A are rectangles having a long side in the X direction, covering approximately the entire width of the radiating element 120A in the X direction. As an example, slits 121A and 122A are of equal size.

[0093] Furthermore, the radiating element 120A of the microstrip antenna 100M1 has: a line 121A1 adjacent to three of the four sides of the slit 121A; and a line 122A1 adjacent to three of the four sides of the slit 122A.

[0094] Line 121A1, adjacent to three of the four sides of slit 121A on the +Y direction side, is a "コ"-shaped line adjacent to two sides of slit 121A extending in the Y direction on both the +X and -X directions, and one side of slit 121A extending in the X direction on the +Y direction. Line 121A1, adjacent to three of the four sides of slit 121A on the -Y direction side, is a line adjacent to two sides of slit 121A extending in the Y direction on both the +X and -X directions, and one side of slit 121A extending in the X direction on the -Y direction. When viewed from above, the line 121A1 on the +Y side and the line 121A1 on the -Y side are symmetrical about a straight line parallel to the X-axis that passes through the center of the width of the connecting element 120B in the Y direction.

[0095] Line 122A1, which is adjacent to three of the four sides of slit 122A on the +Y direction side, is a "コ"-shaped line adjacent to two sides of slit 122A that extend in the Y direction on both the +X and -X directions, and one side of slit 122A that extends in the X direction on the +Y direction. Line 122A1, which is adjacent to three of the four sides of slit 122A on the -Y direction side, is a line adjacent to two sides of slit 122A that extend in the Y direction on both the +X and -X directions, and one side of slit 122A that extends in the X direction on the -Y direction. When viewed from above, the lines 122A1 on the +Y side and -Y side are linearly symmetrical about the X-axis, with the line parallel to the X-axis at the center of the width of the Y-direction passing through the connecting element 120B as the axis of symmetry.

[0096] Slits 121B and 122B are provided on the +Y direction side and the -Y direction side of the connecting element 120B, respectively. The slits 121B and 122B on the +Y direction side are arranged in this order from the +Y direction side of the connecting element 120B towards the center of its width in the Y direction. The slits 121B and 122B on the -Y direction side are arranged in this order from the -Y direction side of the connecting element 120B towards the center of its width in the Y direction.

[0097] Furthermore, the connecting element 120B has: a line 121B1 located in the Y direction further out than slit 121B; and a line 122B1 located between slits 121B and 122B. The two ends of lines 121B1 and 122B1 in the X direction are connected to two adjacent radiating elements 120A.

[0098] When adjusting the resonant frequency of the fabricated surface-mount microstrip antenna 100 to the desired resonant frequency, the lengths La and Lb of the radiating element 120A are shortened by cutting the line 121A1 (see reference). Figure 3 This can increase the resonant frequency. Furthermore, by further reducing lines 121A1 and 122A1, the lengths La and Lb of the radiating element 120A can be shortened (see reference). Figure 3 This can further increase the resonant frequency.

[0099] Here, Figure 12 as well as Figure 13The microstrip antenna 100M1 shown has eight slits 121A. When adjusting for resonant frequency alignment, it is not necessary to cut all eight slits 121A1; the resonant frequency can be gradually adjusted by cutting them one by one. Furthermore, when cutting one slit 121A1, the resonant frequency can also be increased by not cutting the entire slit 121A1, for example, by cutting only the central portion of the side extending in the X direction.

[0100] Similarly, it is not necessary to cut all eight sets of lines 121A1 and 122A1. The resonant frequency can be adjusted gradually by cutting them one set at a time. In addition, when cutting one set of lines 121A1 and 122A1, the resonant frequency can also be increased by not cutting the entire set of lines 121A1 and 122A1, for example by cutting only the central part of the side extending in the X direction.

[0101] Furthermore, when adjusting the resonant frequency of the fabricated surface-mount microstrip antenna 100 to the desired resonant frequency, the length Lb of the radiating element 120A is extended by cutting the line 121B1 (see reference). Figure 3 This can lower the resonant frequency. Furthermore, the length Lb can be increased by cutting lines 121B1 and 122B1 (see [reference]). Figure 3 This can further reduce the resonant frequency.

[0102] Here, Figure 12 as well as Figure 13 The microstrip antenna 100M1 shown has eight slits 121B. When adjusting for resonant frequency alignment, it is not necessary to cut all eight slits 121B1; the resonant frequency can be adjusted gradually by cutting them one by one. Furthermore, when cutting one slit 121B1, the resonant frequency can also be lowered by not cutting the entire slit 121B1, for example, by cutting only the central portion in the X direction.

[0103] Similarly, it is not necessary to cut all eight sets of lines 121B1 and 122B1; the resonant frequency can be adjusted gradually by cutting them one set at a time. Furthermore, when cutting one set of lines 121B1 and 122B1, the resonant frequency can also be lowered by not cutting the entire set of lines 121B1 and 122B1, for example, by cutting only the central part of the side extending in the X direction.

[0104] In the microstrip antenna 100M1 of Modified Example 1, a plurality of radiating elements 120A have slits 121A and 122A provided on the front end side as viewed from the central portion 120A1 of the plurality of radiating elements 120A connected to the connecting element 120B. Furthermore, the connecting element 120B has a plurality of slits 121B and 122B arranged in the Y direction extending from the plurality of radiating elements 120A.

[0105] By cutting lines 121A1 and 122A1 adjacent to slits 121A and 122A, or lines 121B1 and 122B1 adjacent to slits 121B and 122B, the resonant frequency can be adjusted after fabricating the microstrip antenna 100M1.

[0106] Figure 14 as well as Figure 15 This is a diagram showing a microstrip antenna 100M2 according to a second modification of the embodiment. The microstrip antenna 100M2 has a structure in which a microelectrode 123A1 is added to the front end of the radiating element 120A and a slit 123B is added to the connecting element 120B. The slit 123B is an elongated opening provided in the connecting element 120B.

[0107] The microelectrode 123A1 is a portion further towards the front end than the cutouts 123A located on the +X and -X directions of the front end of the radiating element 120A. The cutout 123A is a cutout located on the X direction side where the edge is missing, intersecting the extension direction (Y direction) of the plurality of radiating elements 120A.

[0108] When adjusting the resonant frequency of the fabricated surface-mount microstrip antenna 100 to the desired resonant frequency, the lengths La and Lb of the radiating element 120A are shortened by cutting the microelectrodes 123A1 to connect the cuts 123A. Figure 3 This can increase the resonant frequency. At this time, the portion of the microelectrode 123A1 that is further from the front end than the cutout 123A can be preserved like an island.

[0109] One slit 123B is provided on the +Y direction side and one on the -Y direction side, which are both wider than the center of the connecting element 120B in the Y direction. The connecting element 120B has a line 123B1 located on the outer side of the slit 123B in the Y direction. The two ends of the line 123B1 in the X direction are connected to two adjacent radiating elements 120A.

[0110] When adjusting the resonant frequency of the fabricated surface-mount microstrip antenna 100 to the desired resonant frequency, the length Lb of the radiating element 120A is extended by cutting the line 123B1 (see reference). Figure 3 This can reduce the resonant frequency.

[0111] Here, Figure 14 as well as Figure 15 The microstrip antenna 100M2 shown has eight microelectrodes 123A1. When adjusting for resonant frequency alignment, it is not necessary to cut all eight microelectrodes 123A1; the resonant frequency can be adjusted gradually by cutting them one by one.

[0112] also, Figure 14 as well as Figure 15 The microstrip antenna 100M2 shown has eight slits 123B. When adjusting for resonant frequency alignment, it is not necessary to cut all eight slits 123B1; the resonant frequency can be adjusted gradually by cutting them one by one. Furthermore, when cutting one slit 123B1, the resonant frequency can also be lowered by not cutting the entire slit 123B1, for example, by cutting only the central portion in the X direction.

[0113] In the microstrip antenna 100M2 of Modified Example 2, the plurality of radiating elements 120A have microelectrodes 123A1 and cutouts 123A on the front end side as viewed from the connection portion 120A1, which is connected to the connecting element 120B of the plurality of radiating elements 120A. Furthermore, the connecting element 120B has a plurality of slits 123B arranged in the Y direction extending from the plurality of radiating elements 120A.

[0114] The resonant frequency can be adjusted after fabricating the microstrip antenna 100M2 by cutting the microelectrode 123A1 and the cut 123A, or the line 123B1 adjacent to the slit 123B.

[0115] The above describes a microstrip antenna with exemplary embodiments of the present invention. However, the present invention is not limited to the specific embodiments disclosed, and various modifications and alterations can be made without departing from the claims.

[0116] Furthermore, this international application claims priority based on Japanese Patent Application No. 2021-025518, filed on February 19, 2021, the entire contents of which are incorporated herein by reference.

[0117] -Symbol Explanation-

[0118] 10 substrate

[0119] 10A Lower surface (an example of the first surface)

[0120] 10B Top surface (an example of the second surface)

[0121] 10C Side View

[0122] 100, 100A, 100B, 100C, 100D, 100M1, 100M2 microstrip antennas

[0123] 110 Grounding electrode

[0124] 120 Antenna Elements

[0125] 120A radiating element

[0126] 120A1 Central Division

[0127] 120B Connecting Component

[0128] 120C Notch

[0129] 121A, 122A slits

[0130] Lines 121A1 and 122A1

[0131] 121B, 122B slits

[0132] Lines 121B1 and 122B1

[0133] 123A Incision

[0134] 123A1 Microelectrode

[0135] 123B Slit

[0136] 123B1 Line

[0137] 130 power supply line

[0138] 131 End (An example of the first end)

[0139] 132 End (Example of the second end, power supply section)

[0140] 140 Connection Line

[0141] 141, 142 ends.

Claims

1. A microstrip antenna, characterized by, A substrate made of a dielectric; a ground electrode provided on a first surface of the substrate; an antenna element having a plurality of radiating elements and a connecting element, wherein the plurality of radiating elements are provided on a second surface of the substrate opposite to the first surface, extend in parallel to each other, and the connecting element is provided on the second surface and extends in a direction crossing the plurality of radiating elements to connect the plurality of radiating elements; a power supply line having a first end portion connected to a portion of a radiating element located at an end portion among the plurality of radiating elements and located on an extension of the connecting element in a plan view, and a second end portion provided on a side surface of the substrate between the first surface and the second surface and supplied with power; and a connection line having a section provided on the side surface of the substrate along the power supply line to connect the radiating element located at the end portion and the ground electrode, the plurality of radiating elements have a slit provided on a front end side viewed from a connecting portion of the plurality of radiating elements connected to the connecting element, or a cutout portion provided on the front end side, and an end edge located on a side in a direction crossing an extending direction of the plurality of radiating elements in a plan view is cut out. A substrate made of a dielectric; 2. A microstrip antenna, characterized by a ground electrode provided on a first surface of the substrate; an antenna element having a plurality of radiating elements and a connecting element, wherein the plurality of radiating elements are provided on a second surface of the substrate opposite to the first surface, extend in parallel to each other, and the connecting element is provided on the second surface and extends in a direction crossing the plurality of radiating elements to connect the plurality of radiating elements; a power supply line having a first end portion connected to a portion of a radiating element located at an end portion among the plurality of radiating elements and located on an extension of the connecting element in a plan view, and a second end portion provided on a side surface of the substrate between the first surface and the second surface and supplied with power; and a connection line having a section provided on the side surface of the substrate along the power supply line to connect the radiating element located at the end portion and the ground electrode, the connecting element has a plurality of slits arranged in a direction in which the plurality of radiating elements extend.

3. The microstrip antenna according to claim 1 or 2, wherein the connecting element connects a central portion in the extending direction of the plurality of radiating elements.

4. The microstrip antenna according to claim 1 or 2, wherein lengths in the extending direction of the plurality of radiating elements are equal.

5. The microstrip antenna according to claim 1 or 2, wherein the extending direction of the plurality of radiating elements and the extending direction of the connecting element are orthogonal in a plan view.

6. The microstrip antenna according to claim 1 or 2, wherein the first end portion of the power supply line and an end portion of the connection line connected to the radiating element located at the end portion are provided on the second surface of the substrate.

7. The microstrip antenna according to claim 1 or 2, wherein ​ ​ The connection lines are two connection lines extending sandwiching the power supply line and together with the power supply line forming a coplanar line. The connection lines are two connection lines extending sandwiching the power supply line and together with the power supply line forming a coplanar line.

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