JP2020036287A - Directional antenna - Google Patents

Abstract

To improve the directivity without increasing the number of members corresponding to waveguide members.SOLUTION: A directional antenna 10 that performs at least one of transmission and reception of electromagnetic wave of wavelength λ includes a power supply unit 1 having a loop unit 11 having a loop shape, a cylindrical parasitic conductor 2 that is provided in the first direction orthogonal to a plane including a loop portion 11 with respect to the loop portion 11, extends in the first direction, and has an open end on the power supply portion 1 side, and a parasitic element 3 that is provided on the opposite side to the parasitic conductor 2 with respect to the loop portion 11 in the first direction such that the distance from the parasitic conductor 2 is provided at a position less than λ/2, and in which the size viewed in the first direction is larger than the loop portion 11.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a directional antenna.

  An electronic device including a radiation wiring functioning as a radiator of a Yagi antenna, a reflecting member functioning as a reflector of the Yagi antenna, a waveguide member functioning as a director of the Yagi antenna, and a wireless communication terminal of an electronic circuit chip. A circuit device is described in Patent Document 1. The size of the waveguide member is slightly smaller than the radiation wiring.

JP 2011-130329 A

  As described above, in the electronic circuit device described in Patent Literature 1, the waveguide member is slightly smaller than the radiation wiring, and therefore, it is necessary to increase the number of waveguide members in order to increase the directivity of radio waves.

  An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide a directional antenna that can improve directivity without increasing the number of members corresponding to waveguide members.

The directional antenna of the present invention,
A directional antenna that performs at least one of transmission and reception of an electromagnetic wave having a wavelength λ,
A power supply unit having a loop portion having a loop shape,
For the loop portion, a cylindrical shape is provided in a first direction orthogonal to a plane including the loop portion, extends in the first direction, and has an open end on the power supply portion side. A parasitic conductor,
In the first direction, the loop portion is provided on a side opposite to the parasitic conductor with respect to the parasitic conductor, and a distance from the parasitic conductor is smaller than λ / 2. A parasitic element whose size when viewed is larger than the loop portion,
It is characterized by having.

  The end of the non-feeding conductor opposite to the end on the feeder side may be a closed end.

A distance between the loop portion and the parasitic conductor in the first direction is λ / 8;
A distance between the loop portion and the parasitic element in the first direction may be λ / 8.

  A length of the parasitic conductor in the first direction may be longer than λ / 4.

  A shape of a peripheral portion when the parasitic conductor is cut along a plane parallel to a plane including the loop portion may be substantially similar to a shape of the loop portion.

  A substrate may be provided inside the parasitic conductor.

The substrate is connected to the power supply unit,
A frequency adjusting element for adjusting the frequency of the electromagnetic wave may be provided at a connection between the substrate and the power supply unit.

  According to the directional antenna of the present invention, directivity can be improved without increasing the number of members corresponding to the waveguide members.

It is a figure showing typically composition of a directional antenna in a 1st embodiment. It is a figure which shows the relationship of the relative magnitude | size of the loop part of a feed part, a parasitic conductor, and a parasitic element when it sees from a 1st direction. It is a figure showing typically composition of a directional antenna in a 2nd embodiment. It is an enlarged view of the connection part of a board | substrate and a power supply part. It is a figure which shows typically the structure of the directional antenna in which a hole is provided in the side surface of the parasitic conductor. It is a figure which shows the directional antenna in 2nd Embodiment, and the directional characteristic of the antenna in a reference structural example. It is a figure which shows typically the structure of the directional antenna which provided the hole in the center of the parasitic element, and provided LED in the hole.

  Hereinafter, embodiments of the present invention will be described, and features of the present invention will be specifically described.

<First embodiment>
FIG. 1 is a diagram schematically illustrating a configuration of a directional antenna 10 according to the first embodiment. The directional antenna 10 according to the first embodiment includes a feeding unit 1, a parasitic conductor 2, and a parasitic element 3.

  The directional antenna 10 according to the first embodiment performs at least one of transmission and reception of an electromagnetic wave having a wavelength λ. The frequency of the electromagnetic wave used is, for example, 2.4 GHz, and the wavelength λ in that case is 0.125 m.

  The power supply section 1 is made of a conductive material, for example, copper, and has a loop section 11 having a loop shape. The loop shape means a circular shape, and a shape in which a current flows in a circular shape when a current flows through the loop portion 11 is called a loop shape. In the present embodiment, the loop portion 11 has a substantially annular shape in plan view. The loop portion 11 can be formed on, for example, an FR4 (Flame Retardant Type4) substrate.

  In addition, a conducting wire for supplying a current or a conducting wire for extracting a current is connected to the power supply unit 1. When a current flows through the feeding unit 1, the current also flows through the parasitic conductor 2 and the parasitic element 3 due to coupling with the loop unit 11.

  The parasitic conductor 2 is provided in the first direction orthogonal to the plane including the loop part 11 with respect to the loop part 11 of the power supply part 1. In the present embodiment, the first direction is the Z-axis direction shown in FIG. The parasitic conductor 2 is provided at a position separated by a predetermined distance, for example, a distance of 5 mm or more and 20 mm or less, for coupling with the power feeding unit 1.

  The parasitic conductor 2 has a cylindrical shape extending in the first direction and having an open end 2a on the power supply unit 1 side. In the present embodiment, of the two ends of the parasitic conductor 2 in the first direction, an end 2b on the opposite side to the end 2a on the feeder 1 side is a closed end. That is, the parasitic conductor 2 has a bottomed cylindrical shape.

  In the present embodiment, the parasitic conductor 2 has a cylindrical shape. That is, the shape of the peripheral edge when the parasitic conductor 2 is cut along a plane parallel to the plane including the loop portion 11 of the power supply unit 1 is circular. When viewed from the first direction, it is preferable that the center of the loop portion 11 of the power supply portion 1 and the center of the parasitic conductor 2 coincide.

  As described above, since the loop portion 11 has a substantially annular shape, the outer shape of the loop portion 11 is substantially circular. In other words, the shape of the peripheral portion when the parasitic conductor 2 is cut along a plane parallel to the plane including the loop portion 11 of the power supply portion 1 is substantially similar to the shape of the loop portion 11. With such a configuration, the feeding section 1 and the parasitic conductor 2 are easily coupled.

  In the present embodiment, the shape of the loop portion 11 is substantially annular, but the shape is not limited to the substantially annular shape. For example, the outer periphery may have a substantially rectangular shape. In that case, the shape of the peripheral portion when the parasitic conductor 2 is cut along a plane parallel to the plane including the loop portion 11 of the power supply unit 1 is defined as a loop by making the shape of the parasitic conductor 2 into a rectangular tube shape. The shape can be substantially similar to the shape of the portion 11.

  The size of the parasitic conductor 2 when viewed from the first direction is preferably equal to or larger than the size of the loop portion 11.

  The parasitic conductor 2 is made of a conductive material, for example, iron.

  The length in the first direction of the parasitic conductor 2 having a cylindrical shape is preferably longer than λ / 4. As will be described later, the directional antenna 10 according to the present embodiment has a strong directivity in the direction of the parasitic element 3 with respect to the feeding unit 1 in the first direction (Z-axis direction). By making the length in the first direction of the parasitic conductor 2 longer than λ / 4, the directivity in the direction of the parasitic conductor 2 with respect to the feeding unit 1 in the first direction is reduced. be able to.

  When the length of the parasitic conductor 2 in the first direction is longer than λ / 4, the end 2b of the parasitic conductor 2 may be an open end.

  The parasitic element 3 has a flat plate shape extending in a direction parallel to a plane including the loop portion 11 of the power supply unit 1. There is no particular limitation on the shape of the parasitic element 3 when viewed from the first direction, and it may be rectangular or circular. In the present embodiment, the shape of the parasitic element 3 when viewed from the first direction is rectangular.

  The parasitic element 3 is made of a conductive material, for example, copper.

  The parasitic element 3 is located on a side opposite to the parasitic conductor 2 with respect to the loop portion 11 of the feeding unit 1 in the first direction, and at a distance from the parasitic conductor 2, more specifically, a parasitic conductor. 2 is provided at a position less than λ / 2 from the end 2a.

  FIG. 2 is a diagram illustrating a relationship between the relative sizes of the loop portion 11, the parasitic conductor 2, and the parasitic element 3 of the feeding unit 1 when viewed from the first direction. As shown in FIG. 2, the parasitic element 3 has a larger size when viewed from the first direction than the loop part 11 of the power supply unit 1. That is, when viewed from the first direction, the outer peripheral end of the parasitic element 3 is located outside the loop portion 11 of the power supply unit 1.

  The parasitic element 3 is provided at a position opposite to the parasitic conductor 2 with respect to the loop portion 11 of the feeding unit 1 and at a distance of less than λ / 2 from the parasitic conductor 2. The current flowing through the parasitic conductor 2 and the current flowing through the parasitic element 3 have the same phase, and the electromagnetic waves radiated from the parasitic conductor 2 can interfere with the electromagnetic waves radiated from the parasitic element 3 to be strengthened. Therefore, the parasitic element 3 operates as a director. Thereby, the directivity in the direction of the parasitic element 3 with respect to the power supply unit 1 in the first direction can be enhanced.

  Here, “the phases of the currents are in phase” does not mean that the phases of the currents completely match, but that the phase difference between one current and the other current is less than ± λ / 4. Similarly, “the phase of the electromagnetic waves is in phase” does not mean that the phases of the electromagnetic waves are completely the same, but means that the phase difference between one electromagnetic wave and the other electromagnetic wave is less than ± λ / 4.

  In addition, since the parasitic element 3 is larger in size when viewed from the first direction than the loop portion 11 of the power supply unit 1, a structure in which a conventional director having a smaller size than the power supply unit 1 is provided. In comparison, the directivity in the direction of the parasitic element 3 with respect to the power supply unit 1 can be further increased. In addition, the directivity in the direction of the parasitic element 3 with respect to the feed unit 1 can be increased without providing a plurality of directors.

  The distance between the loop portion 11 of the feeding unit 1 and the end 2b of the parasitic conductor 2 in the first direction is λ / 8, and the distance between the loop unit 11 and the parasitic element 3 in the first direction is Preferably, the distance is λ / 8. By setting the distance between the loop 11 and the end 2b of the parasitic conductor 2 and the distance between the loop 11 and the parasitic element 3 to λ / 8, electromagnetic waves radiated from the parasitic conductor 2 Can be caused to interfere with each other by matching the phase with the electromagnetic wave radiated from the parasitic element 3. Thereby, the directivity in the direction of the parasitic element 3 with respect to the power supply unit 1 in the first direction can be maximized.

<Second embodiment>
FIG. 3 is a diagram schematically illustrating a configuration of a directional antenna 10A according to the second embodiment. The directional antenna 10A according to the second embodiment further includes a substrate 4 and a frequency adjustment element 5 with respect to the directional antenna 10 according to the first embodiment.

  The substrate 4 is provided inside the tubular parasitic conductor 2. The substrate 4 is provided with various sensors, for example. In FIG. 3, the substrate 4 is arranged in a direction parallel to the XZ plane, but the arrangement position and the orientation of the substrate 4 are not limited to the arrangement position and the orientation shown in FIG.

  The substrate 4 is connected to the power supply unit 1. As shown in FIG. 4, a connection between the power supply unit 1 and the substrate 4 is provided with a frequency adjustment element 5 for adjusting the frequency of an electromagnetic wave that performs at least one of transmission and reception. The frequency adjustment element 5 is, for example, an inductor or a capacitor. By providing the frequency adjusting element 5, the frequency of the electromagnetic wave to be used can be easily adjusted to a desired frequency.

  Here, the parasitic conductor 2 may be provided with a hole 40 on the side surface, as shown in FIG. For example, wiring from an external device (not shown) can be connected to the substrate 4 provided inside the parasitic conductor 2 through the hole 40 of the parasitic conductor 2. In this case, the wiring from the external device may include a conductor for supplying current to the power supply unit 1 or a conductor for extracting current.

  FIG. 6 is a diagram illustrating the directional antenna 10A according to the second embodiment and the directional characteristics of the antenna according to the reference configuration example. FIG. 6A shows the directional characteristics of the directional antenna 10A in the second embodiment, and FIGS. 6B to 6D show the directional characteristics of the antenna in the reference configuration example. The antenna exhibiting the directional characteristics shown in FIG. 6B has a configuration in which the parasitic conductor 2 is removed from the directional antenna 10A according to the second embodiment. 6C, the parasitic element 3 is removed from the directional antenna 10A in the second embodiment, and the parasitic conductor 2 surrounds not only the substrate 4 but also the power supply unit 1. Thus, the configuration is such that the length of the parasitic conductor 2 is increased. 6C, the parasitic element 3 of the directional antenna 10A in the second embodiment is not a flat plate but a rectangular loop.

  6A to 6D, the directional characteristics in the vertical direction represent the directional characteristics on the YZ plane including the substrate 4, and the parasitic conductor 2 in the first direction with respect to the power supply unit 1. Is 0 °, and the direction in which the parasitic element 3 is provided is 180 °. The directional characteristics in the horizontal direction represent directional characteristics on the XY plane including the power supply unit 1.

  In a configuration in which the parasitic conductor 2 is removed from the directional antenna 10A in the second embodiment, that is, in an antenna having a feeding unit and a parasitic element, the parasitic element operates as a reflector. As shown in (b), the directivity in the direction of the parasitic conductor 2 with respect to the power supply unit 1 in the first direction is strong.

  FIGS. 6C and 6D show an antenna having a configuration in which a tubular parasitic conductor is provided so as to surround a feeding unit and a substrate, and a loop antenna in which a parasitic element is not a flat plate but a loop. As shown, the directivity in the direction of the parasitic element 3 with respect to the feed unit 1 in the first direction is strong, but the half-value angle is 95 ° and the directivity is not so sharp. .

  On the other hand, in the directional antenna 10A according to the second embodiment, as shown in FIG. 6A, of the first direction, the direction of the parasitic conductor 2 with respect to the The directivity is strong, and a sharp directivity is obtained with a half-value angle of 55 °.

  In the directional antenna 10 according to the first embodiment, similarly, the directivity in the direction of the parasitic conductor 2 with respect to the feed unit 1 is strong and a sharp directivity is obtained.

<Modification>
FIG. 7 is a diagram schematically illustrating a configuration of a directional antenna 10B in which a hole 50 is provided in the center of the parasitic element 3 and an LED 51 is provided in the hole 50. The LED 51 is connected to the substrate 4 by a connection line 52 and is supplied with power. For example, the directional antenna 10 </ b> B may be installed on the ceiling of the room, and the room may be illuminated by the LED 51.

  The components provided in the holes 50 of the parasitic element 3 are not limited to the LEDs 51, and components other than the LEDs 51 can be provided as needed.

  The present invention is not limited to the above embodiments, and various applications and modifications can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Feeding part 2 Parasitic conductor 3 Parasitic element 4 Substrate 5 Frequency adjustment element 10, 10A, 10B Directional antenna 11 Loop part 40 Hole provided on side surface of parasitic conductor 50 Hole provided in center of parasitic element 51 LED

Claims (7)

A directional antenna that performs at least one of transmission and reception of an electromagnetic wave having a wavelength λ,
A power supply unit having a loop portion having a loop shape,
For the loop portion, a cylindrical shape is provided in a first direction orthogonal to a plane including the loop portion, extends in the first direction, and has an open end on the power supply portion side. A parasitic conductor,
In the first direction, the loop portion is provided on a side opposite to the parasitic conductor with respect to the parasitic conductor, and a distance from the parasitic conductor is smaller than λ / 2. A parasitic element whose size when viewed is larger than the loop portion,
A directional antenna, comprising:   The directional antenna according to claim 1, wherein an end of the non-feeding conductor opposite to the end on the feeder side is a closed end. A distance between the loop portion and the parasitic conductor in the first direction is λ / 8;
The directional antenna according to claim 1, wherein a distance between the loop portion and the parasitic element in the first direction is λ / 8.   The directional antenna according to claim 1, wherein a length of the parasitic conductor in the first direction is longer than λ / 4.   5. The shape of a peripheral portion when the parasitic conductor is cut along a plane parallel to a plane including the loop portion, is substantially similar to the shape of the loop portion. 6. The directional antenna according to any of the claims.   The directional antenna according to any one of claims 1 to 5, wherein a substrate is provided inside the parasitic conductor. The substrate is connected to the power supply unit,
The directional antenna according to claim 6, wherein a frequency adjusting element for adjusting the frequency of the electromagnetic wave is provided at a connection between the substrate and the power supply unit.

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