JP2008085587A - Radiator, and antenna device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiator capable of obtaining high performance with a simple structure, and to provide an antenna device including the radiator. <P>SOLUTION: The radiator 1 includes: a radiation part 2 formed in a loop shape and having two power feeding points FD1, FD2; and a parasitic element 4 formed on the outer side of the radiation part 2 along a part of the radiation part 2 including the two power feeding points FD1, FD2. Since the parasitic element 4 is arranged along a part of the radiation part 2 including the power feeding points FD1, FD2, the parasitic element 4 receives comparatively large energy from the radiation part 2, so as to allow resonance to easily occur. The radiation part 2 is set to have the peripheral length so as to allow resonance to occur at a frequency higher than the center frequency of the usage frequency of the radiator 1. The parasitic element 4 is set to have the peripheral length, so as to resonate with frequency being lower than the center frequency of the usage frequency band in the radiator 1. Consequently, the band of the radiator 1 is enlarged. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a radiator and an antenna device including the radiator, and more particularly to a radiator capable of obtaining high performance with a simple structure, and an antenna device including the radiator.

  There are various types of radiators. Among them, a radiator (so-called “loop antenna”) obtained by processing elements such as a conductor or a conductor in a loop shape has been widely used.

  For example, Japanese Patent Laying-Open No. 2006-50439 (Patent Document 1) discloses a phosphorus group antenna device for digital terrestrial broadcasting provided with a plurality of loop-shaped radiating elements. This antenna device includes a loop-shaped main radiating element having a peripheral length of about one wavelength, and a loop-shaped sub-radiating element arranged in front of the main radiating element.

Further, for example, Japanese Patent Application Laid-Open No. 2004-328587 (Patent Document 2) discloses an antenna device in which a parasitic element is arranged inside each of two loop portions constituting a double loop antenna. According to the above document, it is possible to widen the band of the antenna device by resonating each loop portion and the parasitic element.
JP 2006-50439 A JP 2004-328587 A

  The antenna device disclosed in Japanese Patent Laying-Open No. 2006-50439 (Patent Document 1) requires a plurality of radiating elements. For this reason, in the above-mentioned antenna device, there is a possibility that the size increases. Further, as the number of elements increases, the assembly cost of the antenna device is likely to increase. Therefore, when the above-described antenna device is manufactured, the cost may increase.

  On the other hand, Japanese Patent Application Laid-Open No. 2004-328587 (Patent Document 2) discloses disposing a parasitic element on a line segment connecting the centers of two loop portions. However, the above document does not particularly disclose the relationship between the performance of the antenna device and the position of the parasitic element.

  An object of the present invention is to provide a radiator capable of obtaining high performance while having a simple structure, and an antenna device including the radiator.

  In summary, the present invention is a radiator, which is formed in a loop shape on a predetermined plane, has a peripheral length set to a length shorter than the center wavelength of a predetermined frequency band, and the first and second power feeds. A radiating portion having a point, and formed on the predetermined plane on the outside of the radiating portion along a part of the radiating portion including the first and second feeding points, and the length from one end to the other end is the center A first parasitic element set to be longer than half of the wavelength.

  Preferably, when the center wavelength is λ, the distance between the first parasitic element and the radiating portion is a predetermined value included in a range of 0.01λ or more and 0.03λ or less.

  Preferably, the distance between the radiator and the first parasitic element at one end of the first parasitic element is a first length, and the radiator and the first parasitic element at the position of the first feeding point are If the interval is a second length, the first length is smaller than the second length.

  More preferably, when the center wavelength is λ, the first and second lengths are selected from a range of 0.005λ or more and 0.03λ or less.

  Preferably, when the central wavelength is λ, the width of the first parasitic element is a value of 0.005λ or more and 0.03λ or less.

  Preferably, when the center wavelength is λ, the width of the radiating portion is a value of 0.005λ or more and 0.03λ or less.

  Preferably, the radiating portion includes a first feeding point and includes a first conductor extending along the first direction, and a second direction connected to the first conductor and orthogonal to the first direction. And a second conductor extending along the line. The width of the second conductor is smaller than the width of the first conductor.

  More preferably, when the center wavelength is λ, the width of the first conductor and the width of the second conductor are selected from the range of 0.005λ or more and 0.03λ or less.

  Preferably, the radiator further includes a second parasitic element that is formed along the radiating section outside the radiating section and surrounds the radiating section together with the first parasitic element.

  When the other situation of this invention is followed, it is an antenna apparatus, Comprising: The radiator in any one of the above-mentioned, and at least one of a director and a reflector are provided.

ADVANTAGE OF THE INVENTION According to this invention, the radiator which can obtain a high performance, though a structure is simple is realizable.
Further, according to the present invention, it is possible to realize an antenna device that can obtain high performance while having a simple structure.

  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.

[Embodiment 1]
FIG. 1 is a diagram illustrating a configuration of the radiator according to the first embodiment.

  Referring to FIG. 1, radiator 1 includes a radiating unit 2 and a parasitic element 4. The radiating portion 2 is formed in a loop shape on the plane A, and has feeding points FD1 and FD2. The parasitic element 4 is disposed on the plane A. The parasitic element 4 is formed along a part of the radiating portion 2 including the feeding points FD1 and FD2.

  In Embodiment 1, the radiation | emission part 2 and the parasitic element 4 are formed with a metal foil on a dielectric film. That is, the surface of the dielectric film corresponds to the plane A. In addition, you may produce each of the radiation | emission part 2 and the parasitic element 4 by processing a metal plate. In this case, a virtual plane A may be set, and the radiation unit 2 and the parasitic element 4 may be arranged on the plane A.

  In the plane A, the X axis and the Y axis are two axes orthogonal to each other. Both the radiating unit 2 and the parasitic element 4 are symmetric with respect to the Y axis. The origin O is the intersection of the X axis and the Y axis, and corresponds to the center point of the radiator 1.

  The shape of the radiation part 2 shown in FIG. 1 is a square. However, the shape of the radiation part 2 is not particularly limited. For example, the shape of the radiation part 2 may be a rectangle. Moreover, the shape of the radiation | emission part 2 is not limited to a tetragon | quadrangle, For example, a triangle etc. may be sufficient and circular, an ellipse, etc. may be sufficient.

  The use frequency band of radiator 1 is a UHF (Ultra High Frequency) band. More preferably, the operating frequency band of radiator 1 is in the range of 470 to 806 MHz. This range includes the frequency band of UHF broadcasting in Japan (470 to 770 MHz) and the frequency band of UHF broadcasting in the United States (470 to 806 MHz).

  Next, the dimension of the radiator 1 of Embodiment 1 is demonstrated. In addition, the dimension shown below is an example, Comprising: The dimension of the radiator 1 can be set appropriately according to the performance, the magnitude | size, etc. which are calculated | required by the radiator 1. FIG.

  The radiating portion 2 is formed in a square shape having a side of about 140 mm. However, there is a gap between the feeding point FD1 and the feeding point FD2. The size of this gap (distance from one end of the radiating portion 2 to the other end) is about 10 mm. Therefore, the length (peripheral length) along the circumferential direction of the radiating portion 2 is about 550 mm (= 140 × 4-10). The width of the radiating portion 2 (the width in the direction from the inside of the radiating portion 2 to the outside of the radiating portion 2) is about 12 mm.

  Next, the dimensions of the parasitic element 4 will be described. Hereinafter, for convenience of explanation, the parasitic element 4 will be described by being divided into two parasitic elements 4A and 4B extending along the Y axis and a parasitic element 4C extending along the X axis.

  In the parasitic elements 4A and 4B, the length in the Y-axis direction is about 85 mm, and in the parasitic element 4C, the length in the X-axis direction is about 170 mm. Therefore, the sum of the length in the Y-axis direction of the parasitic elements 4A and 4B and the length in the X-axis direction of the parasitic element 4C (in other words, the length from one end to the other end of the parasitic element 4). Is about 340 mm (= 85 × 2 + 170).

  On the other hand, in the parasitic elements 4A and 4B, the width (line width) in the X-axis direction is about 6 mm. The parasitic element 4C has a width (line width) in the Y-axis direction of about 6 mm. That is, the width of the parasitic element 4 in the direction from the inner side of the radiating unit 2 to the outer side of the radiating unit 2 is a predetermined value (about 6 mm).

  The distance between the radiating section 2 and the parasitic element 4A, the distance between the radiating section 2 and the parasitic element 4B, and the distance between the radiating section 2 and the parasitic element 4C are all about 9 mm. That is, the interval between the parasitic element 4 and the radiation part 2 is a predetermined value (about 9 mm).

The length of the radiator 1 in the X-axis direction is about 170 mm.
In the first embodiment, the parasitic element 4 is arranged close to the radiating unit 2. When power is supplied to the feeding points FD1 and FD2 of the radiating unit 2, the radiating unit 2 is excited. Furthermore, the radiation part 2 and the parasitic element 4 can be made to resonate by transferring energy between the radiation part 2 and the parasitic element 4.

  When the radiating unit 2 and the parasitic element 4 resonate, the radiator 1 equivalently forms a double-tuned circuit that tunes to the resonant frequency of the radiating unit 2 and the resonant frequency of the parasitic element. In other words, the radiator 1 operates as a radiator having both the characteristics of the radiating unit 2 and the characteristics of the parasitic element 4. By making the resonance frequency of the radiating unit 2 different from the resonance frequency of the parasitic element 4, the band of the radiator 1 can be widened.

  Considering the current distribution of the radiating unit 2, the current value at the feeding points FD 1 and FD 2 is the largest, and the current value becomes smaller at a position away from the feeding points FD 1 and FD 2 in the radiating unit 2. This is because relatively large energy is released from the vicinity of the feeding points FD1 and FD2 when the radiation unit 2 is fed, whereas the radiation unit 2 is relatively small from a position away from the feeding points FD1 and FD2. It means that energy is released.

  In the first embodiment, the parasitic element 4 is arranged along a part of the radiating unit 2 including the feeding points FD1 and FD2. As a result, the parasitic element 4 is likely to resonate by receiving relatively large energy from the radiating portion 2. Since it becomes possible to resonate the radiation | emission part 2 and the parasitic element 4, when the radiator 1 is operated, desired performance can be obtained.

  Furthermore, the perimeter of the radiating unit 2 is set so as to resonate at a frequency higher than the center frequency of the used frequency band of the radiator 1. On the other hand, the length of the parasitic element 4 is set so as to resonate at a frequency lower than the center frequency of the use frequency band of the radiator 1. As a result, the radiator 1 can exhibit good performance over the entire use frequency band.

  In order to cause the radiating unit 2 to resonate at a frequency higher than the center frequency of the operating frequency band of the radiator 1, the perimeter of the radiating unit 2 is set to be shorter than the center wavelength (about 600 mm) of the operating frequency band of the radiator 1. (About 550 mm). On the other hand, since the parasitic element 4 is resonated at a frequency lower than the center frequency of the operating frequency band of the radiator 1, the length from one end of the parasitic element 4 to the other end is the center of the operating frequency band of the radiator 1. It is set to be longer than half of the wavelength (about 600 mm) (about 340 mm).

  By setting the length of the parasitic element 4 as described above, the wavelength of the radio wave transmitted (or received) from the parasitic element 4 when the radiating unit 2 and the parasitic element 4 are excited can be changed. The wavelength can be doubled. This wavelength is longer than the center wavelength of the used frequency band of the radiator 1. Therefore, the parasitic element 4 can be resonated at a frequency lower than the center frequency of the use frequency band of the radiator 1.

<Characteristics of the radiation unit alone>
FIG. 2 is a diagram illustrating an example in which the size of the radiation unit 2 illustrated in FIG. 1 is changed.

  Referring to FIG. 2, let L be the length of one side of radiation portion 2A (ie, a square). When the length L is changed, the peripheral length of the radiating portion 2A is changed. As a result, the resonance frequency of the radiating portion 2A changes. Therefore, the frequency characteristics of the radiation part 2A also change.

  FIG. 3 is a diagram illustrating the frequency characteristics of the gain of the radiating unit 2A when the side length L of the radiating unit 2A in FIG. 2 is changed.

  Referring to FIG. 3, each of dotted line k1, solid line k2, broken line k3, one-dot chain line k4, and two-dot chain line k5 has a side length L of the radiating portion 2A of about 130 mm, about 140 mm, about 150 mm, It is the frequency characteristic of the gain of the radiation part 2A in the case of about 160 mm and about 170 mm.

  The frequency at which the gain reaches a peak is substantially equal to the resonance frequency of the radiating portion 2A. 3 that the resonance frequency increases as the side length L of the radiating portion 2A is shorter. That is, the shorter the circumference of the radiating portion 2A, the higher the resonance frequency of the radiating portion 2A.

  FIG. 4 is a diagram for explaining the relationship between the side length L of the radiating portion 2A of FIG. 2 and the VSWR (Voltage Standing Wave Ratio) of the radiating portion 2A.

  Referring to FIG. 4, dotted line k6, solid line k7, broken line k8, one-dot chain line k9, and two-dot chain line k10 have side lengths L of radiation part 2A of about 130 mm, about 140 mm, about 150 mm, The frequency characteristics of the VSWR of the radiation part 2A in the case of about 160 mm and about 170 mm are shown. In particular, in the range of about 470 MHz to about 710 MHz, the longer the length L of the side of the radiating portion 2A, the lower the VSWR.

<Characteristics of radiator according to Embodiment 1>
FIG. 5 is a diagram illustrating a first comparative example of the radiator according to the first embodiment.

  With reference to FIGS. 5 and 2, the radiating portion 2B is a radiator corresponding to the radiating portion 2A when the length L of one side of the square is about 130 mm.

FIG. 6 is a diagram illustrating a second comparative example of the radiator according to the first embodiment.
With reference to FIG. 6 and FIG. 2, the radiating portion 2 </ b> C is a radiator corresponding to the radiating portion 2 </ b> A when the length L of one side of the square is about 170 mm.

  FIG. 7 is a diagram showing the gain of the radiator of the first embodiment and the gains of the first and second comparative examples.

  Referring to FIG. 7, dotted lines k11, dash-dot line k12, and solid line k13 indicate radiation part 2B in FIG. 5 (shown as “130 × 130” in FIG. 7) and radiation part 2C in FIG. 6 (“170 in FIG. 7). × 170 ”) and the frequency characteristics of the gain of the radiator 1 of FIG. 1 (shown as“ parasitic element arrangement ”in FIG. 7).

  As indicated by the dotted line k11, the gain of the radiating unit 2B increases as the frequency increases. On the other hand, as indicated by a two-dot chain line k12, the gain of the radiating portion 2C increases as the frequency decreases. That is, the radiating section 2B has excellent performance in a frequency band higher than the center frequency, whereas the radiating section 2C has excellent performance in a frequency band lower than the center frequency.

  On the other hand, the gain of the radiator 1 is approximately the same as the gain of the radiating unit 2B in the high frequency band of the use frequency band, and is approximately the same as the gain of the radiating unit 2C in the low frequency band of the use frequency band. In other words, it can be said that the gain of the radiator 1 is stable and high over the entire use frequency band.

  FIG. 8 is a diagram illustrating the VSWR of the radiator of the first embodiment and the VSWRs of the first and second comparative examples.

  Referring to FIG. 8, dotted line k14, two-dot chain line k15, and solid line k16 indicate radiating portion 2B in FIG. 5 (shown as “130 × 130” in FIG. 7) and radiating portion 2C in FIG. And VSWR frequency characteristics of the radiator 1 of FIG. 1 (shown as “parasitic element arrangement” in FIG. 7). As can be seen by comparing the dotted line k14, the two-dot chain line k15, and the solid line k16, it can be said that the VSWR of the radiator 1 is generally lower than the VSWR of the radiating unit 2B and the VSWR of the radiating unit 2C.

  The higher the gain, the better the performance of the radiator. The lower the VSWR, the better the performance of the radiator. 7 and 8, it can be seen that it is difficult to stabilize the performance over the entire frequency band of the radiator only by adjusting the peripheral length of the radiator. However, by combining the radiating portion and the parasitic element as in the first embodiment, it is possible to exhibit excellent performance over the entire use frequency band of the radiator.

<First Modification>
FIG. 9 is a diagram illustrating a first modification of the radiator according to the first embodiment.

  Referring to FIG. 9, radiator 1 </ b> A is an example in which the interval between parasitic element 4 and radiating unit 2 is variously set in radiator 1 of the first exemplary embodiment. In FIG. 9, the interval between the parasitic element 4C and the radiating portion 2 is indicated as a1, and the interval between the parasitic element 4A and the radiating portion 2 (and the interval between the parasitic element 4B and the radiating portion 2) is indicated as a2. Note that the interval a1 is equal to the interval a2. Therefore, the space | interval of the parasitic element 4 and the radiation | emission part 2 is constant.

  The first modification is an example in which the interval a1 (and the interval a2) is changed every 3 mm within a range of about 3 mm to about 15 mm. As the distance a1 changes, the overall length L1 of the radiator 1A along the X-axis direction changes between about 158 mm, about 164 mm, about 170 mm, about 176 mm, and about 182 mm.

FIG. 10 is a diagram showing the gain of radiator 1A shown in FIG.
Referring to FIG. 10, a dotted line k21, a broken line k22, a solid line k23, a one-dot chain line k24, and a two-dot chain line k25 have intervals a1 (and intervals a2) shown in FIG. 9 of about 3 mm, about 6 mm, about The frequency characteristics of the gain of the radiator 1A in the case of 9 mm, about 12 mm, and about 15 mm are shown. In FIG. 10, a point to be particularly noted is that when the interval a1 (and the interval a2) is about 3 mm, the gain is greatly reduced when the frequency is lower than about 530 MHz.

  On the other hand, when the interval a1 (and the interval a2) is in the range of about 6 mm to about 15 mm, the gain varies depending on the interval a1, but the difference is such that no particular problem occurs in practical use.

FIG. 11 is a diagram showing VSWR of radiator 1A of FIG.
Referring to FIG. 11, a dotted line k26, a broken line k27, a solid line k28, a one-dot chain line k29, and a two-dot chain line k30 have an interval a1 (and interval a2) shown in FIG. The frequency characteristic of VSWR of radiator 1A in the case of 9 mm, about 12 mm, and about 15 mm is shown. In FIG. 11, when the interval a1 (and the interval a2) is about 3 mm, the VSWR becomes significantly worse as the frequency becomes lower than about 530 MHz. On the other hand, when the interval a1 (and the interval a2) is in the range of about 6 mm to about 15 mm, the VSWR varies depending on a1, but the difference is such that no particular problem occurs in practical use.

  That is, if the range of the interval a1 (and the interval a2) is in the range of about 6 mm to about 15 mm, the performance of the radiator can be obtained with no practical problem. The center wavelength of the used frequency band of radiator 1A is about 600 mm. Therefore, when the center wavelength of the used frequency band is λ, a preferable range of the distance a1 is 0.01λ or more and 0.03λ or less.

<Second Modification>
FIG. 12 is a diagram illustrating a second modification of the radiator according to the first embodiment.

  Referring to FIG. 12 and FIG. 1, radiator 1 </ b> B is different from radiator 1 in that it includes parasitic element 41 instead of parasitic element 4. The parasitic element 41 is different from the parasitic element 4 in line width.

  The parasitic elements 4A1, 4B1, and 4C1 in FIG. 12 correspond to the parasitic elements 4A, 4B, and 4C in FIG. 1, respectively. In FIG. 12, the line width of the parasitic elements 4A1 and 4B1 is indicated as b1, and the line width of the parasitic element 4C1 is indicated as b2. The line width b1 is equal to the line width b2.

  The second modification is an example in which the line width b1 (and the line width b2) is changed every 3 mm within a range of about 3 mm to about 15 mm. When the line width b1 changes as described above, the entire length L1 of the radiator 1A along the X-axis direction changes between about 164 mm, about 170 mm, about 176 mm, about 182 mm, and about 188 mm.

FIG. 13 is a diagram showing the gain of radiator 1B of FIG.
Referring to FIG. 13, a dotted line k31, a broken line k32, a solid line k33, a one-dot chain line k34, and a two-dot chain line k35 have a line width b1 (and a line width b2) shown in FIG. 12 of about 3 mm and about 6 mm, respectively. , About 9 mm, about 12 mm, and about 15 mm, the frequency characteristics of the gain of the radiator 1B are shown. Even if the line width b1 (and line width b2) is set within this range, there is no significant difference in the frequency characteristics of the gain.

FIG. 14 is a diagram showing VSWR of radiator 1B of FIG.
Referring to FIG. 14, a dotted line k36, a broken line k37, a solid line k38, a one-dot chain line k39, and a two-dot chain line k40 have a line width b1 (and line width b2) shown in FIG. 12 of about 3 mm and about 6 mm, respectively. , About 9 mm, about 12 mm, about 15 mm, the frequency characteristic of VSWR of radiator 1B is shown. When the line width b1 (and the line width b2) is about 12 mm, the VSWR decreases as the frequency becomes lower than about 530 MHz. However, except for this point, even if the line width b1 (and line width b2) is set within the above range, there is no significant difference in the frequency characteristics of the VSWR.

  That is, if the range of the line width b1 (and the line width b2) is set to a range of about 3 mm to about 15 mm, practically sufficient performance can be obtained with respect to the gain and the VSWR over almost the entire use frequency band. Similar to the first modification, the range of the line width b1 (and line width b2) will be described in relation to the center wavelength of the used frequency band. The line width of the parasitic element is 0.005λ or more and 0. It is preferable if it is within the range of 03λ or less.

  Further, the line width of the parasitic element may be changed continuously (or discontinuously) within the above range.

[Embodiment 2]
FIG. 15 is a diagram illustrating a configuration of the radiator according to the second embodiment.

  Referring to FIGS. 15 and 1, radiator 11 is different from radiator 1 in that it further includes parasitic element 6.

  The parasitic element 6 is formed on the plane A. The parasitic element 6 is formed along the radiation part 2 outside the radiation part 2, and surrounds the radiation part 2 together with the parasitic element 4.

  The parasitic element 6 is arranged symmetrically with the parasitic element 4 with respect to the X axis. The lengths of the parasitic elements 4 and 6 are equal. In FIG. 15, the portions of the parasitic element 6 positioned on the opposite side of the parasitic elements 4A, 4B, and 4C with respect to the X axis are denoted as parasitic elements 6A, 6B, and 6C, respectively.

  In the second embodiment, the parasitic elements 4 and 6 are arranged so as to surround the radiating section 2, and the radiating section 2 and the parasitic elements 4 and 6 are effectively utilized by using the energy output from the radiating section 2. Can be made to resonate. In the second embodiment, the parasitic elements 4 and 6 are excited, so that the performance (particularly gain) in the low frequency band of the usable frequency band of the radiator 11 can be increased.

FIG. 16 is a diagram showing the gains of the radiators of the first and second embodiments.
Referring to FIG. 16, broken line k41 indicates the frequency characteristic of the gain of the radiator of the first embodiment (shown as “140 × 140 lower half” in FIG. 16), and solid line k42 indicates the radiation of the second embodiment. FIG. 16 shows the frequency characteristics of the gain of the device (shown as “140 × 140, upper and lower two arrangements” in FIG. 16). In particular, the gain in the range of the low frequency band (for example, 470 MHz to 650 MHz) of the used frequency band of the radiator is higher in the radiator of the second embodiment than in the radiator of the first embodiment.

FIG. 17 is a diagram showing the VSWR of the radiators according to the first and second embodiments.
Referring to FIG. 17, broken line k43 indicates the frequency characteristic of VSWR of the radiator according to the first embodiment (shown as “140 × 140 lower half” in FIG. 17), and solid line k44 indicates the radiation according to the second embodiment. The frequency characteristics of the VSWR of the device (shown as “140 × 140, upper and lower two arrangements” in FIG. 17) are shown. The radiator according to the second embodiment generally has a lower VSWR than the radiator according to the first embodiment.

  As can be seen from FIGS. 16 and 17, by arranging the parasitic elements 4 and 6 so as to surround the radiating portion 2, the radiator of the second embodiment can obtain higher performance than the first embodiment. It is.

<First Modification>
FIG. 18 is a diagram illustrating a first modification of the radiator according to the second embodiment.

  Referring to FIGS. 18 and 15, radiator 11 </ b> A is different from radiator 11 in that radiation unit 21 is provided instead of radiation unit 2. The radiating part 21 is different in width from the radiating part 2.

  The radiating portion 21 includes two conductors 21A and 21B extending along the X-axis direction, conductors 21C and 21D extending along the Y-axis direction and connected to the conductors 21A and 21B, respectively, and along the X-axis direction. And a conductor 21E extending and connected to the conductors 21C and 21D. The width of the conducting wires 21C and 21D (width in the X-axis direction) is W1, and the width of the conducting wires 21A and 21B (width in the Y-axis direction) is W2. Although not shown in FIG. 18, the width of the conducting wire 21E (the width in the Y-axis direction) is also equal to W2. The line width W1 is equal to the line width W2.

  The first modification is an example in which the line width W1 (and the line width W2) is changed every 3 mm in a range of about 9 mm to about 18 mm.

FIG. 19 is a diagram showing the gain of radiator 11A in FIG.
Referring to FIG. 19, dotted line k51, broken line k52, solid line k53, and alternate long and short dash line k54 have line widths W1 (and line width W2) shown in FIG. 18 of about 18 mm, about 15 mm, about 12 mm, and about 9 mm, respectively. The frequency characteristic of the gain of the radiator 11A in the case is shown. When the line width W1 (and the line width W2) is set within this range, for example, the gain tends to decrease as the line width becomes narrower in a frequency range of about 710 MHz to about 800 MHz. However, the difference in gain in the above frequency range is a difference that does not cause a significant effect on practical use.

FIG. 20 is a diagram illustrating the VSWR of the radiator 11A of FIG.
Referring to FIG. 20, dotted line k55, broken line k56, solid line k57, and alternate long and short dash line k58 have line widths W1 (and line width W2) shown in FIG. 18 of about 18 mm, about 15 mm, about 12 mm, and about 9 mm, respectively. The frequency characteristic of VSWR of radiator 11A in the case is shown. For example, when the line width W1 is about 9 mm, the VSWR tends to increase as the frequency increases. However, when the line width W1 (and the line width W2) is in the above range, the VSWR is maintained at approximately 2.0 or less in the use frequency band of the radiator. If VSWR is about 2.0 or less, it is a level with no practical problem.

<Second Modification>
FIG. 21 is a diagram illustrating a second modification of the radiator according to the second embodiment.

  Referring to FIGS. 21 and 18, radiator 11 </ b> B is different from radiator 11 </ b> A in that radiation unit 22 is provided instead of radiation unit 21. Radiator 11B radiates in that the distance between parasitic element 4A and radiation part 22 (and the distance between parasitic element 4B and radiation part 22) is smaller than the distance between parasitic element 4C and radiation part 22. Different from the vessel 11A.

  To describe a specific example, the interval between the parasitic element 4A and the radiating portion 22 (and the interval between the parasitic element 4B and the radiating portion 22) is about 6 mm. On the other hand, the interval between the parasitic element 4C and the radiating portion 22 is about 9 mm.

  Further, the interval between the parasitic element 6 and the radiating portion 22 is set in the same manner as the interval between the parasitic element 4 and the radiating portion 22. The spacing between the parasitic element 6A and the radiating portion 22 and the spacing between the parasitic element 6B and the radiating portion 22 are about 6 mm. On the other hand, the distance between the parasitic element 6C and the radiation part 22 is about 9 mm.

  The current distribution of the radiating unit 22 is largest at the positions of the feeding points FD1 and FD2, and becomes smaller as the distance from the feeding points FD1 and FD2 increases. As described above, the energy output from the radiating unit 2 at the position becomes smaller as the position is farther from the feeding points FD1 and FD2 in the radiating unit.

  In the radiator 11B, the radiation part 2 and the parasitic element 4 are brought close to each other at positions away from the feeding points FD1 and FD2, so that the radiation energy from the radiation part 22 can be efficiently received even at the end of the parasitic element 4. It becomes possible. Thereby, since the radiation | emission part 22 and the parasitic element 4 become easy to resonate rather than the radiators 11 and 11A, a higher performance can be acquired. Since the parasitic element 6 has the same effect as the parasitic element 4, the radiating portion 22 and the parasitic element 6 can resonate. Thereby, the radiator 11B can obtain higher performance than the radiator 11 of FIG. 15 or the radiator 11A of FIG.

  For this reason, it is preferable that the distance between the end portion of the parasitic element 4 (6) and the radiation portion 22 is small. However, if the parasitic element 4 (6) is too close to the radiating portion 22, there may be a problem that affects the operation of the radiator 11B, for example, the parasitic element 4 and the radiating portion 22 are in contact with each other. For this reason, the minimum value of the space | interval of the edge part of the parasitic element 4 (6) and the radiation | emission part 22 is set, for example to about 3 mm.

  If the center wavelength of the used frequency band of radiator 11B is λ (about 600 mm), “about 3 mm in length” is equal to 0.01λ.

  In addition, the radiating portion 22 includes conducting wires 22A to 22E. The conducting wires 22A to 22E are conducting wires respectively corresponding to the conducting wires 21A to 22E of the radiating portion 21 in FIG. In the case of the radiation portion 22 shown in FIG. 21, the line width W1 and the line width W2 shown in FIG. 18 are different. More specifically, the line width W1 is about 3 mm, about 6 mm, or about 12 mm, and the line width W2 is constant at about 12 mm.

FIG. 22 is a diagram showing the gain of radiator 11B of FIG.
Referring to FIG. 22, broken line k61, solid line k62, and alternate long and short dash line k63 indicate the frequency characteristics of the gain of radiator 11B when the line width W1 shown in FIG. 21 is about 12 mm, about 6 mm, and about 3 mm, respectively. Show. Within this range, there is a difference in the gain of radiator 11B, but it can be said that the difference is slight.

FIG. 23 is a diagram showing the VSWR of the radiator 11B of FIG.
Referring to FIG. 23, broken line k64, solid line k65, and alternate long and short dash line k66 indicate the frequency characteristics of VSWR of radiator 11B when the line width W1 shown in FIG. 21 is about 12 mm, about 6 mm, and about 3 mm, respectively. Show. Within this range, although there is a difference in VSWR of radiator 11B, it can be said that the difference is slight.

  To summarize the first and second modifications, it can be seen that the line width of the radiating portion can be set within a range of about 3 mm to about 18 mm. Here, if the center wavelength of the used frequency band of the radiator is λ (about 600 mm), the above range is 0.005λ or more and 0.03λ or less. In addition, if it is this range, the line | wire width of a radiation | emission part may be fixed and may change continuously.

  Further, in the second modification, the maximum value of the distance between the radiating portion and the parasitic element is about 18 mm (0.03λ), similar to radiator 1A shown in FIG. 9 (modification 1 of the first embodiment). It becomes. Summarizing the above description, in the case of the second modification, the interval between the radiating portion and the parasitic element is selected from the range of 0.005λ to 0.03λ.

[Configuration example of antenna device]
FIG. 24 is a diagram illustrating a configuration example of an antenna device including the radiator according to the present embodiment.

  With reference to FIG. 24, the antenna device 50 includes a radiator 1, a director 7, and a reflector 8. Although FIG. 24 shows the radiator 1 according to the first embodiment, any of the radiators 1A, 1B, 11, 11A, and 11B may be used for the antenna device 50 in place of the radiator 1.

  Radiator 1, director 7 and reflector 8 are arranged such that their centers pass through the Z axis. Note that the direction of the Z-axis indicates the transmission direction of radio waves to be received (or transmitted).

  Radiator 1 includes a dielectric film 51, and a radiation portion 2 and a parasitic element 4 that are formed of a metal foil on the surface of the dielectric film 51. The director 7 includes a dielectric film 52 and a conductor pattern 12 formed on the surface of the dielectric film 52. The reflector 8 includes a dielectric film 53 and a conductor pattern 13 formed on the surface of the dielectric film 53.

  The shapes of the waveguide 7 and the reflector 8 are not limited to the shapes shown in FIG. 24, and may be linear, for example. Moreover, the radiator 1, the director 7, and the reflector 8 may be formed by processing a metal plate.

  The antenna device 50 may be used as either a reception antenna or a transmission antenna. Hereinafter, a case where the antenna device 50 is used as a receiving antenna will be described.

  The director 7 performs a function of guiding the radio wave arriving at the antenna device 50 to the radiator 1. The reflector 8 reflects the radio wave that has reached the reflector 8 toward the radiator 1. Thereby, the antenna device 50 functions as a directional antenna. In order for the antenna device 50 to function as a directional antenna, the antenna device 50 only needs to include at least one of the waveguide 7 and the reflector 8.

  By providing the radiator of the present embodiment, the number of elements of the antenna device 50 can be reduced. Therefore, according to the present embodiment, it is possible to obtain a high-performance antenna device with a simple structure.

  The antenna device 50 may further include a waterproof cover. In this case, the antenna device 50 can be used outdoors.

  Moreover, it is also possible to use only the radiator 1 as a receiving antenna (or transmitting antenna). In this case, the installation space of the radiator 1 can be reduced by attaching the radiator 1 to a window glass of a building, for example. Furthermore, a high gain antenna device can be realized by attaching a plurality of radiators 1 to the window glass.

  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.

It is a figure which shows the structure of the radiator of Embodiment 1. FIG. It is a figure which shows the example which changed the magnitude | size of the radiation | emission part 2 shown in FIG. It is a figure explaining the frequency characteristic of the gain of the radiation | emission part 2A when changing the length L of the edge | side of the radiation | emission part 2A of FIG. It is a figure explaining the relationship between the side length L of the radiation | emission part 2A of FIG. 2, and VSWR (Voltage Standing Wave Ratio: Voltage standing wave ratio) of the radiation | emission part 2A. 6 is a diagram illustrating a first comparative example of the radiator according to the first embodiment. FIG. It is a figure which shows the 2nd comparative example of the radiator of Embodiment 1. FIG. It is a figure which shows the gain of the radiator of Embodiment 1, and the gain of the 1st and 2nd comparative example. It is a figure which shows VSWR of the radiator of Embodiment 1, and VSWR of the 1st and 2nd comparative example. It is a figure which shows the 1st modification of the radiator of Embodiment 1. FIG. It is a figure which shows the gain of 1 A of radiators of FIG. It is a figure which shows VSWR of 1 A of radiators of FIG. It is a figure which shows the 2nd modification of the radiator of Embodiment 1. FIG. It is a figure which shows the gain of the radiator 1B of FIG. It is a figure which shows VSWR of the radiator 1B of FIG. It is a figure which shows the structure of the radiator of Embodiment 2. FIG. It is a figure which shows the gain of the radiator of Embodiment 1 and Embodiment 2. FIG. It is a figure which shows VSWR of the radiator of Embodiment 1 and Embodiment 2. FIG. It is a figure which shows the 1st modification of the radiator of Embodiment 2. FIG. It is a figure which shows the gain of 11 A of radiators of FIG. It is a figure which shows VSWR of the radiator 11A of FIG. It is a figure which shows the 2nd modification of the radiator of Embodiment 2. FIG. It is a figure which shows the gain of the radiator 11B of FIG. It is a figure which shows VSWR of the radiator 11B of FIG. It is a figure which shows the structural example of an antenna apparatus provided with the radiator of this Embodiment.

Explanation of symbols

  1, 1A, 1B, 11, 11A, 11B Radiator, 2, 2A, 2B, 2C, 21, 22 Radiator, 4, 4A, 4B, 4C, 4A1, 4B1, 4C1, 6, 6A, 6B, 6C, 41 Parasitic element, 7 Waveguide, 8 Reflector, 12, 13 Conductor pattern, 21A to 21E, 22A to 22E Conductor, 50 Antenna device, 51 to 53 Dielectric film, A plane, FD1, FD2 Feed point, O origin.

Claims (10)

A radiating portion that is formed in a loop shape on a predetermined plane, has a perimeter set to a length shorter than the center wavelength of a predetermined frequency band, and has first and second feeding points;
On the predetermined plane, it is formed outside the radiating portion along a part of the radiating portion including the first and second feeding points, and the length from one end to the other end is the center wavelength. And a first parasitic element set to be longer than half.   The distance between the first parasitic element and the radiating portion is a predetermined value included in a range of 0.01λ or more and 0.03λ or less, where the center wavelength is λ. The radiator described.   The distance between the radiator at the one end of the first parasitic element and the first parasitic element is a first length, and the radiator and the first at the position of the first feeding point The radiator according to claim 1, wherein the first length is smaller than the second length when a distance from the parasitic element is a second length.   The radiator according to claim 3, wherein the first and second lengths are selected from a range of 0.005λ or more and 0.03λ or less, where λ is the center wavelength.   2. The radiator according to claim 1, wherein when the center wavelength is λ, the width of the first parasitic element is not less than 0.005λ and not more than 0.03λ.   The radiator according to claim 1, wherein the width of the radiating portion is a value of 0.005λ or more and 0.03λ or less, where λ is the center wavelength. The radiation part is
A first conductor including the first feeding point and extending along a first direction;
A second conductor connected to the first conductor and extending along a second direction orthogonal to the first direction;
The radiator according to claim 1, wherein a width of the second conductor is smaller than a width of the first conductor.   The radiation according to claim 7, wherein the width of the first conductor and the width of the second conductor are selected from a range of 0.005λ or more and 0.03λ or less, where λ is the center wavelength. vessel.   The radiator according to claim 1, further comprising a second parasitic element that is formed along the radiating section outside the radiating section and surrounds the radiating section together with the first parasitic element. . A radiator according to any one of claims 1 to 9,
An antenna device comprising at least one of a director and a reflector.

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