antenna

Abstract

To suppress the generation of unnecessary radiation.SOLUTION: An antenna includes a resonator formed by a ground conductor plate, and at least a portion of the ground conductor plate has a notch, the notch satisfies a condition that the notch exists at the position of at least a part of the antinode of a virtual standing wave which is a standing wave that may occur when there is no notch.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] There are antennas such as a triplate antenna, which have a structure in which a specific structure is sandwiched between two ground planes. In such antennas, one ground plane and the other ground plane act as a parallel plate resonator. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Hasegawa, Arata et al., "Design of a Tri-Plate Line Dual-Distributed Offset-Fed Slot Wideband Unidirectional Antenna," IEICE Technical Report, vol. 111, no. 288, AP2011-113, pp. 137-140, November 2011. [Non-patent document 2] Manabu Yamamoto and Akihiko Ito, "Suppression of Parallel Plate Modes in a Triplate-Type Slot-Coupled Microstrip Antenna," IEICE Transactions on Electronics, Information and Communication Engineers, Vol. J80-B, pp. 333-341, April 1997 [Non-patent document 3] Naoya Yamamoto et al., "Design of a Wideband Planar Array Antenna Using Biplanar Circuits and Leaf-Shaped Bowtie Slot Elements," IEICE Technical Report, vol. 121, no. 126, AP2021-43, pp. 109-114, July 2021 Summary of the Invention [Problem to be solved by the invention]

[0004] However, unwanted resonance in the parallel plate mode can occur at the resonant frequency, resulting in unwanted radiation from the edges of the printed circuit board acting as a radiation slot.

[0005] In view of the above circumstances, an object of the present invention is to provide a technique for suppressing the generation of unwanted radiation. [Means for solving the problem]

[0006] One aspect of the present invention is an antenna comprising a resonator formed of a ground conductor plate, wherein at least a portion of the ground conductor plate has a notch, and the notch satisfies the condition that it is located at the position of at least a part of an antinode of a virtual standing wave, which is a standing wave that occurs when no notch is present. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress the generation of unnecessary radiation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a first explanatory diagram illustrating an overview of an antenna according to an embodiment. [Figure 2] FIG. 2 is a second explanatory diagram illustrating an overview of the antenna according to the embodiment. [Figure 3] FIG. 2 is a diagram showing an example of an equivalent structure of the antenna according to the embodiment. [Figure 4] FIG. 3 is an explanatory diagram illustrating an example of the detailed structure of a first ground conductor plate in the embodiment. [Figure 5] 5A and 5B are explanatory diagrams illustrating the relationship between a virtual standing wave and a notch in the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (Embodiment) Fig. 1 is a first explanatory diagram illustrating an antenna 100 according to an embodiment. More specifically, Fig. 1 is an example of a diagram in which each component included in the antenna 100 according to an embodiment is shown separately to facilitate understanding of the antenna 100. Fig. 2 is a second explanatory diagram illustrating an overview of the antenna 100 according to an embodiment. More specifically, Fig. 2 is an example of a cross-sectional view of the antenna 100 according to an embodiment.

[0010] The antenna 100 includes a first ground conductor plate 1, a first dielectric substrate 2, a strip line 3, a coupler 4, a second dielectric substrate 5, and a second ground conductor plate 6. The antenna 100 is, for example, a triplate antenna.

[0011] The first ground conductor plate 1 is a ground conductor plate. The first dielectric substrate 2 is a dielectric substrate. The strip line 3 is a strip line formed on the substrate surface of the first dielectric substrate 2. The coupler 4 is a coupler formed on the substrate surface of the first dielectric substrate 2 and coupled to the strip line 3. The second dielectric substrate 5 is a dielectric plate different from the first dielectric substrate 2 and is in contact with the second ground conductor plate 6. The second ground conductor plate 6 is a ground conductor plate different from the first ground conductor plate. In the example of Figures 1 and 2, the second ground conductor plate 6 has a radiation slot 7. The radiation slot 7 is, for example, an opening opened in the second ground conductor plate 6.

[0012] The following describes the arrangement of the first ground conductor plate 1, the first dielectric substrate 2, the strip line 3 and the coupler 4, the second dielectric substrate 5, and the second ground conductor plate 6. In the antenna 100, the first ground conductor plate 1, the first dielectric substrate 2, the strip line 3 and the coupler 4, the second dielectric substrate 5, and the second ground conductor plate 6 are stacked in one axial direction as shown in FIG.

[0013] Specifically, one surface of the first ground conductor plate 1 contacts one surface of the first dielectric substrate 2. The other surface of the first dielectric substrate 2 contacts one surface of the strip line 3 and the coupler 4. The other surfaces of the strip line 3 and the coupler 4 contact one surface of the second dielectric substrate 5. The other surface of the second dielectric substrate 5 contacts one surface of the second ground conductor plate 6.

[0014] In FIG. 2, the reference numeral 3 (4) denotes the strip line 3 and the coupler 4, and the reference numeral 6 (7) denotes the second ground conductor plate 6 and the radiation slot 7.

[0015] The first dielectric substrate 2, the strip line 3, the coupler 4, and the second dielectric substrate 5 are an example of a structure in which the antenna 100 exists in the space sandwiched between the first ground conductor plate 1 and the second ground conductor plate 6. It is sufficient that there is a space between the first ground conductor plate 1 and the second ground conductor plate 6 that has an electromagnetic wave mode. Therefore, the space sandwiched between the first ground conductor plate 1 and the second ground conductor plate 6 may be, for example, a dielectric, a liquid, a gas, or a cavity. The second ground conductor plate 6 does not necessarily need to have the radiation slot 7.

[0016] Fig. 3 is a diagram showing an example of an equivalent structure of antenna 100 of the embodiment. More specifically, Fig. 3 is a cross-sectional view of the equivalent structure of antenna 100. Even more specifically, Fig. 3 is a cross-sectional view of antenna 200, which is an antenna having the equivalent structure of antenna 100.

[0017] Antenna 200 is a resonator comprising a first equivalent ground conductor plate 8, an equivalent space 9, and a second equivalent ground conductor plate 10. Since antenna 200 is an equivalent structure of antenna 100, first equivalent ground conductor plate 8 is an equivalent structure of first ground conductor plate 1. Therefore, first equivalent ground conductor plate 8 is a ground conductor plate.

[0018] Furthermore, since the antenna 200 is an equivalent structure of the antenna 100, the equivalent space 9 is an equivalent structure to the structure formed by the set of the first dielectric substrate 2, the strip line 3, the coupler 4, and the second dielectric substrate 5. The equivalent space 9 may be any structure that is equivalent to the structure formed by the set of the first dielectric substrate 2, the strip line 3, the coupler 4, and the second dielectric substrate 5.

[0019] As described above, the first dielectric substrate 2, the strip line 3, the coupler 4, and the second dielectric substrate 5 are an example of a structure in which the antenna 100 exists in the space sandwiched between the first ground conductor plate 1 and the second ground conductor plate 6. Therefore, the equivalent space 9 may be any space as long as it is equivalent to the space between the first ground conductor plate 1 and the second ground conductor plate 6. Therefore, the equivalent space 9 may be, for example, a dielectric, a semiconductor, a liquid, a gas, or a cavity.

[0020] Furthermore, since the antenna 200 is an equivalent structure to the antenna 100, the second equivalent ground conductor plate 10 is an equivalent structure to the second ground conductor plate 6. Therefore, the second equivalent ground conductor plate 10 is a ground conductor plate. Therefore, the antenna 100 can also be said to be an example of the antenna 200.

[0021] FIG. 4 is an explanatory diagram illustrating an example of the detailed structure of the first ground conductor plate 1 in the embodiment. The first ground conductor plate 1 is a ground conductor plate with notches. The notches are placed at positions that satisfy a standing wave suppression condition, which is a condition related to the position of the notches. The standing wave suppression condition is a condition that the notches exist at the positions of at least some of the antinodes of a virtual standing wave. The virtual standing wave is a standing wave that occurs when no notches are placed.

[0022] 4 has been described using the first ground conductor plate 1 as an example, this is for the sake of simplicity, and the same can be done for the second ground conductor plate 6. Therefore, the antenna 100 only needs to have a slit that satisfies the standing wave suppression condition in either or both of the first ground conductor plate 1 and the second ground conductor plate 6. In other words, it only needs to have a slit that satisfies the standing wave suppression condition in at least a portion of the first ground conductor plate 1 and the second ground conductor plate 6. Hereinafter, the condition that either or both of the first ground conductor plate 1 and the second ground conductor plate 6 have a slit that satisfies the standing wave suppression condition will be referred to as a structural condition.

[0023] As described above, the equivalent structure of the first ground conductor plate 1 is the first equivalent ground conductor plate 8, and the equivalent structure of the second ground conductor plate 6 is the second equivalent ground conductor plate 10. Therefore, the structural condition is also a condition that at least a portion of the first equivalent ground conductor plate 8 and the second equivalent ground conductor plate 10 has a notch that satisfies the standing wave suppression condition.

[0024] Hereinafter, when there is no need to distinguish between the first ground conductor plate 1 and the second ground conductor plate 6, they will be referred to as resonance-forming plates.

[0025] Furthermore, a resonance-forming plate that satisfies the standing wave suppression condition satisfies the condition that notches exist at the positions of at least some of the antinodes of the virtual standing wave, so for example, notches may exist at the positions of all of the antinodes, or notches may exist at the positions of some of the antinodes.

[0026] FIG. 5 is an explanatory diagram illustrating the relationship between a virtual standing wave and a notch in an embodiment. Wave W101 in FIG. 5 is an example of a virtual standing wave. FIG. 5 shows the relationship between a virtual standing wave and the position of a notch in a resonance-forming plate using a triplate antenna as an example. Note that this is an example used for simplicity of explanation, and similar virtual standing waves will occur in an antenna whose equivalent structure is a resonator and does not have a notch.

[0027] Figure 5 shows, using a cross-sectional view and a top view of the triplate antenna, that the notch is located at the antinode of the virtual standing wave W101. If a notch is located at the antinode of the virtual standing wave, the antinode will be open at the antinode position, and as a result, the virtual standing wave will no longer exist.

[0028] Therefore, antenna 100 or antenna 200, which has a notch in its resonance-forming plate that satisfies the standing wave suppression condition, can suppress the occurrence of virtual standing waves. Because virtual standing waves are the source of unwanted radiation, suppressing the occurrence of virtual standing waves means suppressing the occurrence of unwanted radiation.

[0029] (Explanation about unwanted radiation) Here, we will explain unwanted radiation using an example in which there is no notch that satisfies the standing wave suppression conditions. The first ground conductor plate 1 and the second ground conductor plate 6 equivalently function as a parallel plate resonator, as shown in Figure 3. Therefore, if there is no notch that satisfies the standing wave suppression conditions, unwanted resonance in the parallel plate mode will occur at a certain resonance frequency. Note that unwanted resonance is defined as resonance that causes unwanted radiation. This unwanted resonance causes the space between the ground conductors at the edge of the printed circuit board to act equivalently as a radiation slot, resulting in unwanted radiation.

[0030] Furthermore, because the long sides of the equivalent radiation slot are short-circuited by the conductor and the short sides are open, unwanted resonances that cause unwanted radiation at the edges of the printed circuit board occur at frequencies where an integer multiple of the wavelength matches the length of the long sides of the equivalent radiation slot, that is, the sizes of the first and second ground conductor plates 1 and 6. However, the resonant frequency changes depending on the relative dielectric constants of the first and second dielectric substrates 2 and 5, and the feed circuit or radiation slot 7. Because unwanted resonances exist at frequencies where the board size matches an integer multiple of the wavelength, it is difficult to move the frequency outside the band simply by changing the board size, particularly in wideband antennas, if there are no notches that satisfy the standing wave suppression conditions.

[0031] This concludes the explanation of unwanted radiation that occurs in an antenna that does not have a notch that satisfies the standing wave suppression condition. In this way, it is difficult to suppress the occurrence of unwanted radiation when there is no notch that satisfies the standing wave suppression condition. On the other hand, antenna 100 or antenna 200 has a notch that satisfies the standing wave suppression condition, so it is possible to suppress the occurrence of unwanted radiation.

[0032] While Fig. 5 shows resonance in the Y direction as an example, the same applies to resonance in the X direction, which is a direction perpendicular to the X direction and parallel to the resonance-forming plate. The Y direction is a direction parallel to the resonance-forming plate and perpendicular to the X direction.

[0033] In the example of Figure 5, the length of the slit is, for example, a quarter of the wavelength of the unwanted resonant frequency. The unwanted resonant frequency is the frequency of the unwanted resonance. Therefore, the wavelength of the unwanted resonant frequency is the wavelength of the virtual standing wave. More specifically, the slit is made, for example, a quarter of the wavelength from the end of the resonance-forming plate perpendicular to the direction in which the standing wave exists. In the example of Figure 5, the direction perpendicular to the direction in which the standing wave exists is the X direction. Therefore, the length of a quarter of the wavelength of the unwanted resonant frequency means that the length of the slit in the direction parallel to the X direction is a quarter of the wavelength of the unwanted resonant frequency.

[0034] The effect when the slit satisfies the condition that the length of the slit is one-fourth the wavelength of the unwanted resonance frequency (hereinafter referred to as the "slit condition") will be described.

[0035] The slit has two ends, one of which is on the end side of the ground conductor and the other is on the opposite side. The opposite end (i.e., the other end) is a short-circuited end. Therefore, the position a quarter wavelength away from the end is open. Therefore, when the slit condition is satisfied, the electric field generated at the antinode of the unwanted resonance can be suppressed more than when the slit condition is not satisfied. However, as is clear from this explanation, even if the slit is not a quarter wavelength, as long as it is approximately a quarter wavelength, it has the effect of suppressing the occurrence of unwanted resonance. Therefore, if the length of the slit is approximately a quarter of the wavelength of the unwanted resonant frequency, it has the effect of further suppressing the occurrence of unwanted resonance. In order to suppress the occurrence of unwanted resonance, the length of the slit does not necessarily have to be exactly a quarter of the wavelength of the unwanted resonant frequency.

[0036] Thus, an antenna having a resonator and having a notch in one or both of the two ground conductor plates forming the resonator, where the notch is located at the position of at least a part of the antinode of the virtual standing wave, can suppress the generation of unwanted radiation. That is, the antenna 100 or antenna 200 of the embodiment configured in this way has a resonance-forming plate with a notch that satisfies the standing wave suppression condition. Therefore, the generation of unwanted radiation can be suppressed.

[0037] (Variation) As described above, the antenna 100 may be, for example, a slit antenna in which the first dielectric substrate 2 serves as an air space and a reflector is loaded. The first dielectric substrate 2 and the second dielectric substrate 5 may be air spaces or semiconductor layers. The antenna 100 may be a single-element antenna or an array antenna having multiple elements.

[0038] Furthermore, the shape of the radiation slot may be any shape as long as it is the shape of a closed figure. Therefore, the shape of the radiation slot may be a rectangle, a circle, an ellipse, a ring, a loop, a polygon, a cross, a bowtie, or a leaf-shaped bowtie. For details on leaf-shaped bowties, see Non-Patent Document 3, "Design of a Wideband Planar Array Antenna Using Biplanar Circuits and Leaf-Shaped Bowtie Slot Elements."

[0039] In the case of a circular antenna, the antenna element itself has a symmetrical structure, which has the effect of allowing the polarization to be changed by the power feeding method.

[0040] Furthermore, in the case of a shape formed by a closed curve such as a ring or loop, a current flows in the closed curve due to electromagnetic induction caused by a magnetic field passing through the surface enclosed by the closed curve. The radiating slot then operates due to the current that flows. Therefore, the radiating slot is more sensitive to magnetic fields than to electric fields, and has the effect of preventing noise caused by nearby electric fields.

[0041] In the case of a cross shape, it is possible to provide an antenna with dual polarization.

[0042] The bowtie or leaf-shaped bowtie shape has the advantage of providing wider bandwidth characteristics than a rectangular shape, since the bowtie or leaf-shaped bowtie is a type of self-complementary antenna. In addition, the polygonal shape has the advantage of providing wider bandwidth characteristics than a rectangular shape, since there are more design parameters.

[0043] Furthermore, the antenna 100 is not limited to an antenna that radiates through a radiation slot. For example, the antenna 100 may be an antenna that includes an antenna such as a microstrip antenna on an upper layer above the radiation slot 7. When an antenna element such as a microstrip antenna is provided on an upper layer above the radiation slot 7, there are more parameters for adjusting impedance matching than when radiating through a rectangular slot, which has the effect of achieving broadband characteristics.

[0044] Although the shape of the coupler 4 for coupling the strip line and the radiation slot is rectangular in the example of Fig. 1, it does not necessarily have to be rectangular. The shape of the coupler 4 may be any shape as long as it is a closed figure, and may be a circle, an ellipse, a ring, or a polygon.

[0045] 1 illustrates an antenna including a strip line 3 and a coupler 4 in the space between the first ground conductor plate 1 and the second ground conductor plate 6. However, the antenna 100 does not necessarily need to include a strip line 3 and a coupler 4 in the space between the first ground conductor plate 1 and the second ground conductor plate 6.

[0046] The strip line 3 in the example of Figure 1 is an example of a feed line. The feed line does not necessarily have to be a strip line, but may be a slot line or a coplanar line. When the feed line is a coplanar line, the electromagnetic field distribution is similar to that of a coaxial line, which has the advantage of facilitating impedance matching. Furthermore, when the feed line is a slot line, it has the advantage of being able to connect semiconductor elements in parallel.

[0047] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Explanation of symbols]

[0048] 100, 200...antenna, 1...first ground conductor plate, 2...first dielectric substrate, 3...strip line, 4...coupler, 5...second dielectric substrate, 6...second ground conductor plate, 7...radiating slot, 8...first equivalent ground conductor plate, 9...equivalent space, 10...second equivalent ground conductor plate

Claims

1. A parallel plate resonator consisting of two ground conductor plates, Equipped with At least a portion of the ground conductor plate has a notch, The slit satisfies the condition that it is present at the position of at least a part of an antinode of a virtual standing wave, which is a standing wave that occurs when no slit is provided. antenna.

2. The length of the slit satisfies the condition of being approximately one-fourth the wavelength of the virtual standing wave.

10. The antenna of claim 1.

3. one of the ground planes has a radiating slot shaped for broadband operation; 3. The antenna according to claim 1 or 2.

4. a strip line and a coupler coupled to the strip line are provided in a space sandwiched between the ground conductor plates; 3. The antenna according to claim 1 or 2.

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