JP5925594B2 - 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, there is a risk of damaging the landscape of the house and the roof may be damaged during installation. Therefore, there is a demand for an antenna with a simple configuration that takes into account the above.

  An example of the planar type antenna is a slot 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 planar conductor, and power is supplied to two positions facing each other across the slit.

  Japanese Patent Application Laid-Open No. 2011-66793 (Patent Document 1) discloses a planar slot antenna in which a conductor plate bent toward the reflector side from each end of the short side and long side of the radiator and a long side bent. The structure which has the side fin which protrudes from a part of conductor plate is disclosed.

JP 2011-66793 A JP 2011-124653 A JP 2011-228554 A JP 2009-17115 A

  In addition to being attached to the wall surface of a house, the planar antenna as described above may be installed indoors. Therefore, further reduction in size and thickness of the planar antenna is desired from the viewpoint of securing installation space and appearance.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a slot type planar antenna that is reduced in size and thickness while maintaining the conventional antenna characteristics. is there.

  An antenna according to the present invention includes first and second radiating elements, a power feeding unit that receives power from the outside, and a power feeding line, and performs at least one of transmission and reception of radio waves. The first and second radiating elements each include a main body having a substantially rectangular shape with a slit formed therein. The feed line supplies power from the feed unit to the first and second radiating elements. The first radiating element and the second radiating element are arranged symmetrically with respect to the power feeding unit so that the slits are substantially collinear.

  Preferably, the antenna further includes at least one resonance element arranged corresponding to each of the first and second radiating elements, facing the main plane of the main body and parallel to the main plane.

  Preferably, the antenna further includes a reflective element arranged to face the first and second radiating elements with a distance therebetween.

  Preferably, the resonant element is disposed between the corresponding first and second radiating elements and the reflecting element.

  Preferably, each of the first and second radiating elements further includes a side fin that protrudes in a direction orthogonal to the slit from a part of an end of each side parallel to the slit in the main body.

  Preferably, each of the first and second radiating elements has a bent portion that is bent toward the surface facing the reflecting element at the end of each side parallel to the slit in the main body.

  Preferably, each of the first and second radiating elements further includes a side fin protruding from a part of each bent portion in a direction perpendicular to the slit.

  Preferably, each of the first and second radiating elements includes a feeding point for connecting to the feeding line. The distance between the feeding point of the first radiating element and the feeding point of the second radiating element is set to a range of approximately λ / 2 to λ, where λ is the center wavelength of the antenna use frequency band. The

  Preferably, the power supply line is configured by flat plates arranged so that the wide surfaces face each other and are parallel to each other.

  Preferably, the antenna further includes a housing that houses the first and second radiating elements, the feed line, and the feed unit. The power supply unit includes a connection unit for connecting to an external power supply medium, and a fixing unit extending from the connection unit in parallel to the power supply line and for positioning with the housing.

  Preferably, each side parallel to the slit of the main body is set to approximately λ / 2, where λ is the center wavelength of the use frequency band of the antenna.

  According to the present invention, a slot type planar antenna can be reduced in size and thickness while maintaining the conventional antenna characteristics.

It is a perspective view of a two-stage stack type planar slot antenna according to the present embodiment. FIG. 2 is an exploded view of the planar slot antenna of FIG. 1. It is a figure which shows a part of AA cross section of FIG. FIG. 2 is a plan view of the planar slot antenna of FIG. 1. It is a figure for demonstrating the detail of the electric power feeding part of the planar slot antenna of FIG. It is a figure which shows an example of the relationship between the gain and frequency of an antenna about the presence or absence of a resonant element, and the installation position of a resonant element. It is a figure which shows an example of the relationship between the VSWR and frequency of an antenna about the presence or absence of a resonance element, and the installation position of a resonance element. It is a figure which shows an example of the comparison of the characteristic of the planar slot antenna which has a single radiation | emission element, and the characteristic of the two-stage stack type planar slot antenna according to this Embodiment. It is a 1st figure which shows the other example of installation of a resonant element. It is a 2nd figure which shows the other example of installation of a resonant element.

  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 a two-stack type planar slot antenna 100 (hereinafter also simply referred to as “antenna”) 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 radiating elements 130 and 140 that are feeding elements, a reflecting element 150 and resonant elements 170 and 180 that are parasitic elements. The radiating elements 130 and 140, the reflecting element 150, and the resonant elements 170 and 180 are accommodated in the substantially rectangular lower casing 110. In FIGS. 1 and 2, the upper housing (not shown) is shown as being removed for easy understanding of the internal structure of the antenna, but these elements are protected in actual use. In order to do so, the upper housing is attached to the lower housing 110.

  An attachment tool 120 is optionally attached to the lower housing 110. With this attachment tool 120, the antenna body can be fixed to a wall surface or a column. Note that when the antenna 100 is installed on the floor surface of the room or the like, a stand (not shown) that can be attached to the housing can be used.

  In the radiating elements 130 and 140, slits 136 and 146 (described later) are substantially straight in the long side direction (X direction in FIGS. 1 and 2) of the lower casing 110 with respect to the power feeding unit 163 that receives power supplied from the outside. It arranges symmetrically so that it may be on a line. That is, the radiating elements 130 and 140 are arranged in a two-stage stack.

  The radiating element 130 includes a main body portion 131, bent portions 132 and 133, and side fins 134 and 135.

  The main body 131 is a conductive plate having a rectangular planar shape when viewed from above, and a slit 136 extending in the long side direction of the lower casing 110 is formed therein. In the main body 131, the slit 136 has a rectangular shape with a distance from each side of the main body 131 along a straight line passing through a substantially midpoint in the short side direction (Y direction in FIGS. 1 and 2) of the lower housing 110. It is formed.

  The main body 131 is provided with a feeding point 137 at a position near the center of the slit 136 in the longitudinal direction and facing the slit 136. A connection point 161 provided at an end of the power supply line 160 is connected to the power supply point 137 by a fastening member 190 such as a bolt. As a result, the power supplied to the power feeding unit 163 is transmitted to the radiating element 130 through the power feeding line 160.

  The bent portions 132 and 133 protrude from the side in the vertical direction (X direction) in the horizontal direction (Y direction) in the main body 131 and bend in the direction of the reflective element 150. As will be described later with reference to FIG. 4, the length of the radiating element 130 in the horizontal direction (Y direction) (that is, the length of the main body 131 and the two bent portions 132 and 133 combined) is the frequency band of the antenna used. When the center wavelength is λ, it is set to approximately λ / 2. In the present invention, the bent portion is not essential, but by bending the end portion of the radiating element 130, the thickness of the end portion of the housing can be reduced while ensuring the lateral length of the radiating element 130. .

  Further, side fins 134 and 135 further protrude from a portion near the center of each of the bent portions 132 and 133. The side fins 134 and 135 are optional, but by providing these, the effect of improving the gain of the middle frequency in the use frequency band can be obtained.

  Although not shown in FIGS. 1 and 2, the end of the side in the horizontal direction (Y direction) of the main body 131 may be further bent.

  The radiating element 140 basically has the same structure as the radiating element 130. Therefore, although the description of the radiating element 140 is not repeated, the main body portion 141, the bent portions 142 and 143, the side fins 144 and 145, the slit 146, and the feeding point 147 in the radiating element 140 are the main body portion 131 and the bent portion in the radiating element 130. 132, 133, side fins 134, 135, slit 136, and feeding point 137, respectively. Further, a connection point 162 provided at an end of the power supply line 160 is connected to the power supply point 147.

  The resonant element 170 is provided in parallel to the radiating element 130 at a predetermined distance. Although the resonant element is not essential in the present invention, it is generally used to improve the gain for a specific frequency, and its length is set according to the frequency to be improved.

  In general, it is preferable that the resonant element 170 is disposed at the same position as the feeding point 137 of the radiating element 130 in view of the shape of the electromagnetic field generated by the radiating element 130.

  In the present embodiment, the connection point 161 of the feed line 160 is connected together with the lower casing 110 to the back side of the feed point 137 of the radiating element 130, that is, the reflective element 150 side. Therefore, in order to arrange at the same position as the feeding point 137, it is necessary to provide on the surface side of the radiating element 130. However, on the other hand, the installation of the resonant element 170 on the surface side of the radiating element 130 may be a factor that hinders the overall thickness of the antenna device.

  Therefore, in the present embodiment, the resonant element 170 is closer to the back side of the radiating element 130, that is, between the radiating element 130 and the reflecting element 150, from the feeding point 137 to the short side end of the lower casing 110. Are provided at a predetermined distance. The same applies to the relationship between the radiating element 140 and the resonant element 180.

  As described above, the power supply line 160 transmits the power supplied from the outside of the antenna supplied to the power supply unit 163 to the radiating elements 130 and 140. The power supply line 160 includes two rigid flat plates arranged so that the wide surfaces face each other and are parallel to each other. Although a wiring can be used as the power supply line, in the case of a wiring, the impedance can change depending on the interval or positional relationship between the two wirings. As in the present embodiment, in the two-stage stack type antenna 100, it is preferable to make impedances from the power feeding unit 163 to the two radiating elements 130 and 140 as equal as possible, so a rigid flat plate as shown in the figure is used. It is more preferable to secure a stable impedance.

  The power feeding unit 163 is provided near the center of the power feeding line 160 in the longitudinal direction. A coaxial cable (not shown) is connected to the power feeding unit 163, and power is supplied from the outside. In addition, although not shown in figure between the electric power feeding part 163 and a coaxial cable, the capacitor | condenser for adjusting an impedance and a matching device may be provided, for example.

  FIG. 3 is a part of a cross-sectional view taken along the line AA in FIG. 1 and shows the relationship between the radiating element 130 (140), the resonant element 170 (180), and the reflecting element 150. As can be seen from FIG. 3, the radiating element, the resonant element, and the reflecting element are arranged such that their principal planes face each other and are parallel to each other.

  FIG. 4 is a plan view of the planar slot antenna of FIG. In FIG. 4, the radiating element 140 is shown as a perspective view, and the resonant element 180 and the like arranged on the back side are shown by broken lines.

  Referring to FIG. 4, the length in the vertical direction (X direction in FIG. 4) of each of radiating elements 130 and 140 is, for example, approximately λ / 2 when the center wavelength of the frequency band of the antenna to be used is λ. Set to As described above, the length of each of the radiating elements 130 and 140 in the horizontal direction (the Y direction in FIG. 4) is also set to, for example, approximately λ / 2.

  The distance between the radiating element 130 and the radiating element 140 is appropriately set so that the distance between the feeding points is in a range between λ / 2 and λ.

  FIG. 5 is an enlarged view of a portion of the power feeding unit 163 in the plan view of FIG. The power feeding part 163 is a flat plate that protrudes in a substantially L shape from each of the power feeding lines 160 arranged in parallel, and a feeding medium (by a fastening member 191 such as a bolt at a connection part 164 protruding from the power feeding line 160. For example, it is electrically connected to a connection terminal (not shown) provided at the end of the coaxial cable. In FIG. 5, the feeding member 163 on the right side of the drawing is shown as a state in which the fastening member 191 is removed so that the connection portion 164 can be seen.

  The power feeding unit 163 includes a fixing unit 165 extending from the connection unit 164 in parallel with the longitudinal direction of the power feeding line 160. For example, the fixing portion 165 is provided with a hole portion 166, and the hole portion 166 is fitted into a convex portion protruding from the lower housing 110.

  Such a structure of the power supply unit 163 is not necessarily an essential structure, but by using such a structure, when the power supply line 160 is fixed to the substrate 195 with a fastening member (for example, a bolt) 191, a bolt tightening torque is used. It is possible to prevent the power supply line 160 from being distorted.

  6 and 7 show the experimental evaluation of the characteristics of the two-stage stack type planar slot antenna according to the present embodiment. FIG. 6 shows a change in gain with respect to frequency, and FIG. 7 shows a change in VSWR with respect to frequency. 6 and 7 are examples of experiments conducted to evaluate the influence of the presence / absence of the resonant element and the arrangement of the resonant elements. The broken lines W10 and W20 in FIGS. The solid lines W11 and W21 show the case where the distance between the feeding point and the resonant element is 40 mm, and the solid lines W12 and W22 show the case where the distance between the feeding point and the resonant element is 30 mm. In addition, a frequency range that is a use band of terrestrial digital broadcasting in the UHF band used by the antenna in the present embodiment is 470 MHz to 710 MHz.

  With reference to FIGS. 6 and 7, in the antenna having no resonant element, the gain is high at both ends (470 to 510 MHz, 730 to 800 MHz) of the illustrated frequency band, but in the middle frequency region, The gain is relatively low (broken line W10 in FIG. 6). Correspondingly, VSWR shows a relatively high value in the middle frequency region (broken line W20 in FIG. 7).

  On the other hand, in the case of having a resonant element, the gain in the medium frequency region (510 MHz to 730 MHz) is higher than that in the case of having no resonant element (solid lines W11 and W12 in FIG. 6). Correspondingly, the VSWR is lower in the frequency region than in the case where no resonant element is provided (solid lines W21 and W22 in FIG. 7).

  As for the influence of the arrangement of the resonance elements, both gain and VSWR have better results as the distance between the resonance element and the feeding point is shorter.

  FIG. 8 shows a one-stage planar slot antenna composed of a single radiating element as disclosed in Japanese Patent Application Laid-Open No. 2011-66793 (Patent Document 1), and two like this embodiment. It is a figure which shows the comparison of the gain between the two-stage stack type planar slot antenna comprised with one radiation element. In FIG. 8, a broken line W30 indicates the gain of the single-stage planar slot antenna, and a solid line W31 indicates the gain of the two-stage stacked planar slot antenna.

  As can be seen from FIG. 8, in the frequency range of 470 MHz to 710 MHz, which is the band used for terrestrial digital broadcasting in the UHF band used in the antenna of the present embodiment, almost the same gain is obtained in any antenna. That is, it can be seen that the characteristics of the conventional single-stage planar slot antenna are maintained even in the two-stage stacked planar slot antenna of the present embodiment.

Here, the dimensions of the casings of the two planar slot antenna examples compared in FIG. 8 are compared. The single-stage planar slot antenna has a length (X direction in FIG. 1): 526 mm, a width (Y direction in FIG. 1): 303 mm, and a thickness (Z direction in FIG. 1): 64 mm. The projected area (length × width) is 159,378 mm ² and the volume (length × width × thickness) is 10,200,192 mm ³ . On the other hand, the two-stage planar slot antenna has a length (X direction in FIG. 1): 610 mm, a width (Y direction in FIG. 1): 225 mm, and a thickness (Z direction in FIG. 1): 57 mm. The area is 137,250 mm ² and the volume is 7,823,250 mm ³ .

  Accordingly, a reduction in size of about 14% is realized in the projected area of the entire antenna, and a reduction in thickness of about 11% is realized in thickness. In addition, a reduction in size of about 23% is realized in comparison of the entire volume.

  It should be noted that the numerical values shown here are merely examples, and are appropriately changed depending on the design of the frequency band used and the dimensions between the radiating elements.

  As described above, the configuration of the two-stack type planar slot antenna as in the present embodiment deteriorates the characteristics as compared with the planar slot antenna composed of one radiating element. The entire antenna can be reduced in size and thickness.

  9 and 10 show variations of the arrangement of the resonant elements. In the antenna 100A of FIG. 9, a plurality of resonant elements are provided for each radiating element. In addition to the resonant element 170, the radiating element 130 is further provided with resonant elements 171 and 172 in parallel with the resonant element 170. In addition to the resonant element 180, resonant elements 181 and 182 are further provided in parallel with the resonant element 180 for the radiating element 140.

  At this time, the lengths of the plurality of resonance elements may be the same or different. The number and length of the resonant elements are appropriately determined according to desired characteristics.

  In the antenna 100B of FIG. 10, the resonant elements 170A and 180A have the width of the resonant element, that is, the length along the long side of the lower casing 110 (the length in the X direction), as shown in FIG. , 180 longer than that. In other words, the resonant element in FIG. 10 can be considered to be a continuous arrangement of the multiple resonant elements shown in FIG.

  Note that the lengths (the lengths in the Y direction) of the resonant elements 170A and 180A may be constant, or the lengths may be changed along the width direction (X direction) of the resonant elements.

  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.

  DESCRIPTION OF SYMBOLS 100 Antenna, 110 Lower housing, 120 Mounting tool, 130,140 Radiation element, 131,141 Body part, 132,133,142,143 Bending part, 134,135,144,145 Side fin, 136,146 Slit, 137, 147 Feed point, 150 Reflective element, 160 Feed line, 161, 162 Connection point, 163 Feed part, 164 Connection part, 165 Fixing part, 166 Hole part, 170, 170A, 171, 172, 180, 180A, 181, 182 Resonance Element, 190,191 fastening member, 195 substrate.

Claims (12)

An antenna for transmitting and / or receiving radio waves,
First and second radiating elements each including a main body having a substantially rectangular shape with a slit formed therein;
A power feeding unit that receives power from the outside,
A power supply line for supplying power from the power supply unit to the first and second radiating elements,
The antenna, wherein the first radiating element and the second radiating element are arranged symmetrically with respect to the feeding portion so that the slits are substantially collinear.   2. The apparatus according to claim 1, further comprising at least one resonance element that corresponds to each of the first and second radiating elements, is disposed opposite to the main plane of the main body portion and parallel to the main plane. Antenna.   The antenna according to claim 2, further comprising a reflective element disposed to face the first and second radiating elements with a distance therebetween.   The antenna according to claim 3, wherein the resonant element is disposed between the corresponding first and second radiating elements and the reflective element.   The antenna according to claim 1, further comprising a reflective element disposed facing the first and second radiating elements at a distance.   Each of the said 1st and 2nd radiation | emission element further has a side fin which protrudes in a direction orthogonal to the said slit from a part of edge part of each side parallel to the said slit in the said main-body part. The antenna of any one of -5.   Each of the said 1st and 2nd radiation | emission element has the bending part bent in the edge part of each side parallel to the said slit in the said main-body part to the surface side facing the said reflection element. The antenna according to any one of claims.   8. The antenna according to claim 7, wherein each of the first and second radiating elements further includes a side fin that protrudes in a direction orthogonal to the slit from a part of each of the bent portions. Each of the first and second radiating elements includes a feed point for connecting to the feed line;
The distance between the feeding point of the first radiating element and the feeding point of the second radiating element is in a range of approximately λ / 2 to λ, where λ is the center wavelength of the use frequency band of the antenna. The antenna according to claim 1, wherein   The antenna according to claim 1, wherein the power supply line is configured by a flat plate arranged such that wide surfaces face each other and are parallel to each other. A housing that houses the first and second radiating elements, the feeding line, and the feeding unit;
The power feeding unit is
A connection for connecting to an external power supply medium;
The antenna according to claim 1, further comprising: a fixing portion that extends in parallel with the feed line from the connection portion and is positioned with the housing.   2. The antenna according to claim 1, wherein each side parallel to the slit of the main body is set to approximately λ / 2, where λ is a center wavelength of a use frequency band of the antenna.

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