JP5026568B2 - antenna - Google Patents

Description

  The present invention relates to an antenna, and more particularly to a planar slot antenna.

  When installing a conventional Yagi-type antenna on the roof, the landscape of the house will be worse, and the roof may be damaged at the time of installation, for example, a flat type antenna that can be attached to a wall surface or a veranda, etc. There is a need for an antenna with a simple configuration that takes landscape into consideration.

  As a conventional planar type antenna, for example, a double loop type antenna can be cited. However, the double-loop type antenna has a drawback that a feeding method and a structure are complicated because it is necessary to provide a plurality of double-loop type radiators in order to increase the gain.

  On the other hand, a slot antenna is an example of a planar type antenna. In a general slot antenna, for example, a slit, that is, a thin slot-shaped hole is provided in the center of a rectangular flat conductor, and power is supplied to two positions facing each other across the slit (see Non-Patent Document 1). In the slot antenna, it is only necessary to provide one feeding portion, so that the feeding method and structure can be simplified as compared with the double loop type antenna.

  As an example of the slot antenna, for example, Japanese Patent Laid-Open No. 2002-84130 (Patent Document 1) discloses the following antenna. That is, a UHF antenna comprising a substantially rectangular radiating conductor constituting a radio wave radiating surface and a reflecting conductor having substantially the same shape as the radiating conductor and arranged in parallel with the back of the radiating conductor, the radiating conductor having a central portion Has an opening window extending in the vertical direction, and a feeding point is provided on the left and right walls of the central portion of the opening window.

  Japanese Patent Laid-Open No. 2003-332834 (Patent Document 2) discloses the following antenna. That is, a conductive plate having a U-shaped cross section composed of a front plate, side plates bent on both sides so as to be substantially orthogonal to the front plate, and a substantially vertical direction from one edge of the front plate in the conductive plate It is comprised by the slot formed in the substantially horizontal direction in the antenna for horizontal polarization comprised by the slit currently formed in the above, the said front board, and the side board formed in the both sides of this front board And a vertically polarized antenna.

JP 2002-84130 A JP 2003-332834 A

The Institute of Electronics, Information and Communication Engineers, “Antenna Engineering Handbook (Second Edition)”, Ohmsha

  In recent years, with the start of terrestrial digital broadcasting, it has become possible to satisfactorily receive television broadcasting with an antenna having a relatively simple configuration compared to analog broadcasting, and the above-described planar type slot antenna is used. Are being studied and put into practical use.

  The flat type slot antenna does not necessarily have to be installed on the roof like a conventional Yagi type antenna, and has the advantage that it can be easily installed on the wall of a house or a veranda fence, etc. There is a demand for smaller and thinner antenna bodies.

  On the other hand, the use frequency band of the antenna is related to the size of the conductor portion of the antenna body, and there is a concern that the antenna characteristics in the use frequency band may be reduced by downsizing the antenna. Therefore, it is desired to reduce the size of the antenna while preventing deterioration of the antenna characteristics or improving the antenna characteristics.

  The present invention has been made to solve such problems, and an object of the present invention is to improve antenna characteristics while preventing an increase in size of a planar slot antenna.

  The antenna according to the present invention comprises a radiator and a director. The radiator includes a first body portion of a conductor having a substantially rectangular shape, a slit is formed inside the rectangle of the first body portion and a power feeding portion, and performs at least one of transmission and reception of radio waves. . The director includes a second body portion of a conductor that is opposed to the radiator at a distance and has a substantially rectangular shape, and a slit is formed inside the rectangle of the second body portion.

  Preferably, each short side of the second main body is formed to be shorter than each short side of the first main body.

Preferably, the length of each long side of the second main body is set in a range of 60 to 100% of the length of each long side of the first main body.

Preferably, each long side of the second main body is set to a length equal to each long side of the first main body.

  Preferably, the radiator further includes a first bent portion and a first side fin. The first bent portion bends toward the surface opposite to the surface facing the director at the end of each long side of the first main body and protrudes in the short side direction. The first side fin protrudes in the short side direction from the approximate center in the long side direction of each first bent portion. The director further includes a second bent portion and a second side fin. The second bent portion is bent at the end of each long side of the second main body portion so as to be substantially parallel to the first bent portion on the side facing the radiator, and protrudes in the short side direction. . The second side fin protrudes in the short side direction from the approximate center in the long side direction of each second bent portion.

  Preferably, the radiator further includes a third bent portion that is bent at a substantially right angle to a surface opposite to the surface facing the waveguide at the end of each short side of the first main body. The director further includes a fourth bent portion that bends at a substantially right angle to the side facing the radiator at the end of each short side of the second main body portion.

  Preferably, when the center wavelength of the frequency band used for the antenna is λ, the distance between the radiator and the director is set to λ / 20 or less.

  Preferably, the length of each short side of the second main body portion is set to be smaller than λ / 2, where λ is the center wavelength of the frequency band used for the antenna.

  Preferably, the length of each short side of the second main body is set in the range of 0.25λ to 0.35λ.

  Preferably, the antenna further includes a reflector disposed opposite to the surface of the radiator opposite to the surface facing the director at a distance.

  Preferably, when the center wavelength of the use frequency band of the antenna is λ, the distance between the radiator and the reflector is set to λ / 10 or less.

  Preferably, the radio wave is a UHF (Ultrahigh Frequency) band radio wave.

  ADVANTAGE OF THE INVENTION According to this invention, in a planar slot antenna, antenna characteristics can be improved, preventing the enlargement of an antenna.

It is a perspective view of the planar slot antenna according to this Embodiment. FIG. 2 is an exploded view of the planar slot antenna of FIG. 1. It is a three-plane figure of the planar slot antenna of FIG. 1, (a) is a top view, (b) is a front view, (c) shows a side view. It is a perspective view of the 1st comparative example of a planar slot antenna. It is a perspective view of the 2nd comparative example of a planar slot antenna. It is a perspective view of the 3rd comparative example of a plane type slot antenna. It is a perspective view of the 4th comparative example of a planar slot antenna. It is a figure which shows an example of the relationship between the gain and frequency of each antenna in a comparative test. It is a perspective view which shows the other example in the planar slot antenna according to this Embodiment. It is a perspective view which shows the further another example in the planar slot antenna according to this Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a perspective view of planar slot antenna 100 according to the present embodiment. FIG. 2 is an exploded view of the planar slot antenna 100 shown in FIG. In the present embodiment, antenna 100 is described as an example of an antenna for transmitting or receiving a UHF (Ultrahigh Frequency) band radio wave. However, the frequency band of the radio wave is not limited to this, for example, VHF (Very High frequency band radio waves may be used.

  Referring to FIGS. 1 and 2, antenna 100 includes a radiator 130 that is a feeding element, and a waveguide 110 and a reflector 150 that are parasitic elements.

  Radiator 130 includes a main body portion 30, bent portions 32, 33, 36 and 37, and side fins 34 and 35.

  The main body 30 is a conductor having a substantially rectangular shape as viewed from above, and a slit 31 extending in the long side direction (Y direction in FIG. 2) is formed inside the rectangle. The slit 31 is formed in a rectangular shape with a distance from each side of the main body 30 along a straight line that bisects the main body 30 in the long side direction, that is, along a substantially midpoint of each short side of the main body 30. The

  Further, the main body portion 30 is provided with a power feeding portion 38 at a position opposed to the main body portion 30 with the slit 31 near the center in the long side direction. A coaxial cable (not shown) is connected to the power supply unit 38. Moreover, although not shown in figure between the electric power feeding part 38 and a coaxial cable, the capacitor | condenser and matching device for adjusting an impedance may be provided, for example.

  The ends of the two long sides of the main body 30 are provided with conductor bent portions 32 and 33 that extend in the long side direction and project in the short side direction (X direction in FIG. 2). The bent portions 32 and 33 are bent toward the reflector 150 side. The bent portions 32 and 33 are provided with side fins 34 and 35 of conductors protruding in the short side direction from the central portion in the long side direction of the main body 30 in the bent portions 32 and 33, respectively. The shape of the side fins 34 and 35 is formed in a rectangular shape, for example. The side fins 34 and 35 are particularly effective in improving the gain of the mid frequency in the used frequency band.

  At the ends of the two short sides of the main body 30, conductor bent portions 36 and 37 are provided that extend in the short side direction and project in the long side direction. The bent portions 36 and 37 are bent toward the reflector 150 side.

  These bent portions 32, 33, 36, and 37 have substantial lengths in the long-side direction and short-side direction while ensuring the overall length of the radiator 130 extending in the long-side direction and short-side direction. The antenna 100 can be shortened and contributes to the reduction in size and thickness of the entire antenna when the antenna 100 is housed in a housing (not shown).

  The director 110 is formed in a shape similar to the radiator 130, and includes a main body 10, bent portions 12, 13, 16, and 17, and side fins 14 and 15. The director 110 is disposed at a position facing the radiator 130.

  The main body 10 is a conductor having a substantially rectangular shape as viewed from above, and a slit 11 extending in the long side direction (Y direction in FIG. 2) is formed inside the rectangle. The slit 11 is formed in a rectangular shape with a distance from each side of the main body 10 along a straight line that bisects the main body 10 in the long side direction, that is, along a substantially middle point of each short side of the main body 10. The

  At the ends of the two long sides of the main body 10, conductor bent portions 12 and 13 are provided that extend in the long side direction and project in the short side direction (X direction in FIG. 2). The bent portions 12 and 13 are bent toward the radiator 130 so as to be substantially parallel to the bent portions 32 and 33 of the radiator 130, respectively. The bent portions 12 and 13 are provided with side fins 14 and 15 of conductors protruding in the short side direction from the central portion of the main body portion 10 in the bent portions 12 and 13 in the long side direction, respectively. The shape of the side fins 14 and 15 is formed in a rectangular shape, for example.

  The ends of the two short sides of the main body 10 are provided with bent portions 16 and 17 of a conductor that extend in the short side direction and project in the long side direction. The bent portions 16 and 17 are bent toward the radiator 130 side.

  The reflector 150 is a conductor that is disposed so that the radiator 130 faces the surface opposite to the surface facing the waveguide 110. Each of the ends in the long side direction of the reflector 150 has a shape bent toward the radiator 130 side. With such a configuration, the length of the reflector 150 in the short side direction can be shortened, and the overall size of the antenna 100 can be reduced.

  3A and 3B are three views when the antenna 100 is assembled. FIG. 3A is a top view, FIG. 3B is a front view, and FIG. 3C is a side view.

  Referring to FIG. 3A, the length in the long side direction of radiator 130 is set to approximately 1.2λ in a specific embodiment, where λ is the center wavelength of the used frequency band of antenna 100. The Further, the length of the radiator 130 in the short side direction is set to approximately λ / 2.

  The director 110 is set such that the length in the long side direction is in the range of 60 to 100% of the length in the long side direction of the radiator 130. Alternatively, preferably, the length of the waveguide 110 in the long side direction is set equal to that of the radiator 130.

  On the other hand, the length in the short side direction of the director 110 is set shorter than the radiator 130, that is, shorter than λ / 2. Preferably, the length in the short side direction of the director 110 is set in the range of 0.25λ to 0.35λ, and in a specific embodiment, is set to approximately 0.3λ.

  In general, in order to obtain good antenna characteristics, the distance between the radiator and the reflector, and the distance between the radiator and the director are required to be set to approximately λ / 4, respectively. . However, as described above, by increasing the length of the radiator in the long side direction, that is, the extending direction of the slit, the distance between the radiator and the reflector and the distance between the radiator and the director are set to λ / 4. Even if it is shorter than this, it is possible to realize wide bandwidth. That is, the characteristics of the antenna 100 include, for example, the gain of the antenna 100, the standing wave ratio (generally referred to as SWR (Standard Wave Ratio) or VSWR (Voltage Standard Wave Ratio)), the front-to-back ratio, and the like. Good characteristics can be obtained and the band can be widened.

  In the present embodiment, as shown in FIG. 3B, for example, the distance between the radiator 130 and the reflector 150 is set to approximately λ / 10, and the distance between the radiator 130 and the waveguide 110 is set. Is set to approximately λ / 20. By doing so, the antenna 100 can be thinned. Note that the distance between the radiator and the reflector and the distance between the radiator and the director are not limited to the distance shown in FIG. 3B, and are appropriately determined according to the desired characteristics and the allowable antenna dimensions. Is set.

  In the antenna 100 described above, the case where the director 110, the radiator 130, and the reflector 150 have a substantially rectangular shape has been described as an example. However, for example, a part of the antenna 100 may be chamfered. Polygons other than rectangles may be used. Further, the slit 11 of the waveguide 110 and the slit 31 of the radiator 130 are not limited to a rectangular shape as long as the shape extends in the long side direction of each main body.

  Next, in order to understand the characteristics of the antenna 100 of the present embodiment, a description will be given of the results of comparative tests in the case of not using a waveguide and in the case of using several waveguides having different shapes. To do.

4 to 7 are schematic views showing the configuration of the antenna used in the comparative test.
An antenna 101 shown in FIG. 4 is an antenna configured without the director 110 in the antenna 100 according to the present embodiment shown in FIG.

  In the antenna 102 shown in FIG. 5, instead of the director 110 of the antenna 100, four small rectangular waveguides 120, 121, 123, and 124 are spaced apart in the long side direction of the radiator 130. The antennas are arranged in parallel.

  An antenna 103 illustrated in FIG. 6 is an antenna using a director 125 in the case where the outer diameter is the same as that of the director 110 but the slit 11 is not provided, instead of the director 110 in the antenna 100.

  An antenna 104 shown in FIG. 7 is an antenna that uses a director 126 when the side fins 14 and 15 of the director 110 are not provided, instead of the director 110 in the antenna 100.

  FIG. 8 is a diagram showing an example of the relationship between the gain and frequency of each antenna in a comparative test using these antennas.

  Referring to FIG. 8, curve W1 represents the characteristics of antenna 101 that does not include the director illustrated in FIG. 4, and curve W2 represents the characteristics of antenna 100 of the present embodiment illustrated in FIG. Further, the curve W3 is the antenna 104 having the waveguide without side fins shown in FIG. 7, the curve W4 is the antenna 103 having the waveguide without slits shown in FIG. 6, and the curve W5 is the small size shown in FIG. The characteristics of the antenna 102 having the above-described waveguide are shown.

  From these characteristics, when the antenna of this embodiment is used (curve W2), an improved gain is obtained over other antennas, particularly in the frequency band of 470 to 700 MHz. Since the frequency currently used in the terrestrial digital broadcasting currently used is 710 MHz or less, it is better than the conventional planar antenna that does not use the director by using the director of the present embodiment. Gain characteristics can be realized.

  In the case of using a waveguide having another different shape, the antenna 104 (curve W3) having the slit but not having the side fin has a slightly lower gain than the antenna of the present embodiment, but is 470 to 700 MHz. In the frequency band, a better gain characteristic is obtained than the conventional antenna without a director.

  The antenna 103 (curve W4) having side fins but no slit has a lower gain than a conventional antenna without a director at all frequencies of 470 to 800 MHz.

  In the case of the antenna 101 (curve W5) having a small waveguide, the gain is about the same as that of the conventional antenna in the frequency band of 470 to 650 MHz, but the gain is remarkably increased at a higher frequency. The result is a decline.

  As described above, in the antenna according to the present embodiment, by using a director having slits and side fins, the gain of the antenna is better than the conventional one while suppressing the increase in size of the antenna and maintaining the thickness reduction. Can be obtained.

Examples of antennas according to other embodiments of the present invention are shown in FIGS.
The antenna 100A in FIG. 9 is an example in which a radiator 130A and a director 110A having slits but no side fins are used. In addition, the antenna 100B in FIG. 10 is an example in which the radiator 130B and the waveguide 110B that have slits but do not have side fins and bent portions in the long side direction are used.

  Both FIG. 9 and FIG. 10 are examples in which the radiator and the director have similar shapes. For example, when adding a director to an existing antenna that does not have a director It is also possible to use a waveguide having such a shape.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  10, 30 Body part, 11, 31 Slit, 12, 13, 16, 17, 32, 33, 36, 37 Bending part, 14, 15, 34, 35 Side fin, 38 Power feeding part, 100, 100A, 100B, 101 , 102, 103, 104 Antenna, 110, 110A, 110B, 120, 121, 123, 124, 125, 126 Waveguide, 130, 130A, 130B Radiator.

Claims (11)

An antenna for transmitting and / or receiving radio waves,
A radiator including a first body portion of a conductor having a substantially rectangular shape, wherein a slit is formed inside the rectangle of the first body portion and having a power feeding portion;
Wherein separating the radiator and the distance to face includes a second body portion of the conductor having a substantially rectangular shape, Bei example a waveguide in which the second rectangle inside the slit of the main body portion is formed,
The radiator is
A third bent portion that bends at a substantially right angle to the surface opposite to the surface facing the waveguide at the end of each short side of the first main body;
The director is
The antenna further comprising a fourth bent portion that bends at a substantially right angle to a surface facing the radiator at an end of each short side of the second main body .   The antenna according to claim 1, wherein the length of each short side of the second main body is set to be shorter than the length of each short side of the first main body.   The length of each long side of the said 2nd main-body part is an antenna of Claim 1 or 2 set to the range of 60 to 100% of the length of each long-side of the said 1st main-body part.   4. The antenna according to claim 3, wherein each long side of the second main body is set to a length equal to each long side of the first main body. The radiator is
A first bent portion that bends to the opposite side of the surface facing the waveguide and protrudes in the short side direction at the end of each long side of the first body portion;
A first side fin that protrudes in the short side direction from the approximate center in the long side direction of each of the first bent portions;
The director is
A second bent portion that is bent at the end of each long side of the second main body portion so as to be substantially parallel to the first bent portion on the side facing the radiator and protrudes in the short side direction. When,
The antenna according to any one of claims 1 to 4, further comprising a second side fin protruding in a short side direction from a substantially center in a long side direction of each of the second bent portions. If the center wavelength of the frequency band used for the antenna is λ,
The antenna according to claim 1, wherein a distance between the radiator and the director is set to λ / 20 or less. If the center wavelength of the frequency band used for the antenna is λ,
The antenna according to claim 1, wherein the length of each short side of the second main body is set to be smaller than λ / 2.   The antenna according to claim 7, wherein a length of each short side of the second main body is set in a range of 0.25λ to 0.35λ.   The antenna of any one of Claims 1-8 further provided with the reflector arrange | positioned facing the surface opposite to the surface facing the said director of the radiator at a distance. If the center wavelength of the frequency band used for the antenna is λ,
The antenna according to claim 9, wherein a distance between the radiator and the reflector is set to λ / 10 or less.   The antenna according to any one of claims 1 to 10, wherein the radio wave is a radio wave in a UHF (Ultra High Frequency) band.

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