JP6419469B2 - Antenna and structure - Google Patents

Description

  The present invention relates to an antenna. The present invention also relates to a structure including an antenna and a metal plate.

  The frequency band used for wireless communication is steadily increasing. For example, even in the frequency band used for LTE (Long Term Evolution) in Japan, there are 800 MHz band, 900 MHz band, 1800 MHz band, 2100 MHz band, and the like, and the addition of 700 MHz band is also planned. In order to cope with such a situation, it is required to realize a multiband antenna having a plurality of frequency bands as an operating band or a wideband antenna having a wide frequency band including these plurality of frequency bands as an operating band. .

  In Patent Document 1, (1) a rectangular ground portion, (2) a first element extending perpendicularly to the ground portion from a hot-side feeding point provided in the ground portion, and (3) provided in the ground portion. An in-vehicle antenna is disclosed that includes a second element that extends perpendicularly from a ground-side feeding point to a ground portion and is turned back to the first element side at an end opposite to the ground-side feeding point. . In Patent Document 1, (a) the length of the first element is made shorter than λ / 4, thereby expanding the operating band to the high frequency side, and (b) capacitively coupling the first element and the second element. Thus, it is described that the operating band is expanded to the low frequency side.

JP 2013-232772 A (published on November 14, 2013)

  However, the operating band of the vehicle-mounted antenna described in Patent Document 1 is defined by the length of the first element, and it is not possible to use both frequency bands that are far apart as the operating band. For this reason, for example, both the 800 MHz band and the 1800 MHz band used for LTE cannot be set as operation bands.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to realize an antenna having an operation band wider than the conventional one.

  In order to solve the above problems, an antenna according to the present invention is an antenna including a first planar conductor and a second planar conductor, and the first planar conductor includes a first strip-shaped portion and an antenna. A second band-shaped portion disposed in parallel with the first band-shaped portion; and one end of the first band-shaped portion and the second band-shaped portion disposed perpendicular to the first band-shaped portion and the second band-shaped portion. A third band-shaped portion connecting the sides, and the second planar conductor is located in a region sandwiched between the first band-shaped portion and the second band-shaped portion. A fourth belt-like portion arranged in parallel with the second belt-like portion, and a protruding portion arranged outside the region sandwiched between the first belt-like portion and the second belt-like portion and connected to the fourth belt-like portion And a feeding point is provided at an end of the fourth belt-shaped portion facing the third belt-shaped portion and the third belt-shaped portion. .

  According to said structure, implement | achieve the antenna with a wider operation | movement band than the past which transmits / receives electromagnetic waves in both the said 4th strip | belt-shaped part which comprises a coplanar line with the said 1st planar conductor, and the said protrusion part. Can do.

  In the antenna according to the present invention, the length of the fourth band-shaped portion is one half or more of the effective wavelength of the electromagnetic wave having the lower limit frequency of the frequency band predetermined as the operation band, and the outer circumference of the protruding portion is Of these, the length of the portion from the center of the side that becomes the boundary with the fourth belt-like portion to one end point of the end opposite to the fourth belt-like portion is the effective wavelength of the electromagnetic wave having the lower limit frequency. It is preferable that it is 1/4 or more.

  According to said structure, the said predetermined frequency band can be made into the operating band of the said antenna.

  In the antenna according to the present invention, the protruding portion is a bell shape obtained by rounding two corners of a rectangle, and a side sandwiched between the two corners is connected to the fourth belt-shaped portion. preferable.

  According to said structure, the operating band of the said antenna can further be expanded to the high frequency side.

  In the antenna according to the present invention, the protruding portion is connected to the fourth belt-like portion through a rectangular conductor piece having a side between the two corners as a long side. preferable.

  According to the above configuration, it is possible to easily match the impedance of the antenna and the impedance of the coaxial cable connected to the antenna only by changing the length of the short side of the conductor piece.

  In the antenna according to the present invention, the first band-shaped portion includes the third band-shaped portion starting from an end portion farther from the second band-shaped portion on the other side opposite to the one end side. It is preferable that a strip-shaped extension portion that extends in a direction away from the first strip-shaped portion and is narrower than the first strip-shaped portion is added.

  According to said structure, the operating band of the said antenna can further be expanded to the low frequency side.

  A structure according to the present invention is a structure including the antenna and a metal plate, and the metal plate includes a first plane portion and a second plane portion, and the first plane portion and the second plane. There is a step between the flat portion, and the antenna has the first belt-like portion facing the first flat portion of the metal plate and the second belt-like portion of the second metal plate. It is arrange | positioned so that a plane part may be opposed, and it is preferable that the distance from the said 2nd strip | belt-shaped part to the said metal plate is longer than the distance from the said 1st strip | belt-shaped part to the said metal plate.

  According to said structure, the operating band of the said antenna can further be expanded to the low frequency side.

  In the structure according to the present invention, the antenna includes the first belt-like portion facing the first flat portion of the metal plate, and the second belt-like portion and the fourth belt-like portion of the metal plate. It is preferable that they are arranged so as to face the two plane portions.

  According to the above configuration, the operating band of the antenna is further expanded to the low frequency side, and the gain in the vicinity of the lower limit of the operating band of the antenna, which may occur when the metal plate is close to the fourth strip conductor. Degradation can be avoided.

According to the present invention, it is possible to realize an antenna having a wider operating band than in the past.

It is a top view of the antenna which concerns on one Embodiment of this invention. It is a figure which shows the example of mounting of the antenna shown in FIG. (A) is a perspective view of an automobile, (b) is a plan view of a decorative board mounted on the pillar, and (c) is a cross-sectional view showing an AA ′ cross section of the decorative board. is there. It is a graph which shows the frequency dependence of VSWR and gain obtained when the antenna shown in FIG. 1 is arrange | positioned in free space. It is a graph which shows the radiation pattern obtained when the antenna shown in FIG. 1 is arrange | positioned in free space. (A) shows a radiation pattern in a band from 698 MHz to 960 MHz, (b) shows a radiation pattern in a band from 1427 MHz to 1790 MHz, and (c) shows a radiation pattern in a band from 1870 MHz to 2140 MHz. , (D) shows a radiation pattern in a band of 2170 MHz to 2500 MHz. It is a graph which shows the frequency dependence of VSWR and gain obtained when the antenna shown in FIG. 1 is mounted in a pillar. It is a graph which shows the radiation pattern obtained when the antenna shown in FIG. 1 is mounted in a pillar. (A) shows a radiation pattern in a band from 698 MHz to 960 MHz, (b) shows a radiation pattern in a band from 1427 MHz to 1790 MHz, and (c) shows a radiation pattern in a band from 1870 MHz to 2140 MHz. , (D) shows a radiation pattern in a band of 2170 MHz to 2500 MHz.

[Configuration of antenna]
A configuration of an antenna 1 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a plan view of an antenna 1 according to the present embodiment.

  As shown in FIG. 1, the antenna 1 includes a first planar conductor 11 and a second planar conductor 12. In the present embodiment, the antenna 1 is formed (for example, printed) on the upper surface of a dielectric substrate 2 whose upper surface and lower surface are rectangular, and constitutes an antenna substrate 3 together with the dielectric substrate 2.

  As shown in FIG. 1, the first planar conductor 11 includes a first strip portion 111, a second strip portion 112, and a third strip portion 113. The first strip portion 111 is a strip-shaped conductor, and is disposed along one long side of the upper surface of the dielectric substrate 2. The second strip portion 112 is a strip conductor, and is disposed along the other long side of the upper surface of the dielectric substrate 2 in parallel with the first strip portion 111. The third strip portion 113 is a strip conductor, and is disposed along one short side of the upper surface of the dielectric substrate 2 perpendicular to the first strip portion 111 and the second strip portion 112. One end 111a of the first strip 111 (in the negative x-axis direction in FIG. 1) and one end 112a of the second strip (in the negative x-axis in FIG. 1) 112a are the third strip. 113 are connected.

  In the embodiment shown in FIG. 1, the length of the first strip 111 is 123.6 mm, and the width of the first strip 111 is 34 mm. Moreover, the length of the 2nd strip | belt-shaped part 112 shall be 123.6 mm, and the width | variety of the 2nd strip | belt-shaped part 112 is 7.4 mm. However, in the section 112b having a length of 7.2 mm including the end side 112a, the width of the second strip portion 112 is narrowed to 3.4 mm. Moreover, the length of the 3rd strip | belt-shaped part 113 is 49 mm, and the width | variety of the 3rd strip | belt-shaped part 113 is 3.4 mm.

  The second planar conductor 12 includes a fourth belt-like part 121 and a protruding part 122. The fourth strip 121 is a strip-shaped conductor having substantially the same length as the first strip 111 and the second strip 112, and is sandwiched between the first strip 111 and the second strip 112. In the region, the first belt-like portion 111 and the second belt-like portion 112 are arranged in parallel. The projecting portion 122 is a conductor having an arbitrary shape (bell shape in the present embodiment), and is disposed outside the region sandwiched between the first strip portion 111 and the second strip portion 112.

  In the embodiment shown in FIG. 1, the length of the fourth strip 121 is 124 mm, and the width of the fourth strip 121 is 6 mm. However, the width of the fourth strip 121 is increased to 10 mm in the section 121a of 6 mm from the end facing the third strip conductor 113. Further, the length of the protruding portion 122 is 43.1 mm, and the width of the protruding portion 122 is 30 mm.

  The inner conductor of the coaxial cable that outputs from the antenna 1 or transmits a high-frequency current that is input to the antenna 1 is the other of the fourth strips 121 of the second planar conductor 12 (in FIG. 1, the x-axis negative direction side). ) Is connected to the end. Hereinafter, the point 121b on the fourth strip 121 to which the inner conductor of the coaxial cable is connected is referred to as a “first feeding point”. In addition, the outer conductor (not shown) of the coaxial cable is located at a position facing the other end of the fourth strip 121 of the second planar conductor 12 in the third strip 113 of the first planar conductor 11. Connected. Hereinafter, the point 113a on the third strip 113 to which the outer conductor of the coaxial cable is connected is referred to as a “second feeding point”.

In the antenna 1 according to the present embodiment, in order to set a frequency band including the frequency f as a lower limit as an operating band, (1) the length of the fourth strip conductor 121 that constitutes the coplanar line together with the first planar conductor 11; (2) Of the outer periphery of the projecting portion 122, a portion from the center A of the side that becomes the boundary with the fourth belt-like portion 121 to one end point B of the side opposite to the fourth belt-like portion 121 (see FIG. The length of the portion along the chain line in FIG. 1 is set as follows. In other words, the length of the fourth band-like portion is set to one half or more of the effective wavelength c / (f × ε ^1/2 ) of the electromagnetic wave having the frequency f. In addition, the length of the portion from the center A of the side that becomes the boundary with the fourth strip 121 to the one end point B of the end opposite to the fourth strip 121 in the outer periphery of the protrusion 122 is It is set to one quarter or more of the effective wavelength c / (f × ε ^1/2 ) of the electromagnetic wave having the frequency f. Here, c is the speed of light (3.0 × 10 ⁸ m / s), and ε is the relative dielectric constant of a dielectric (for example, the dielectric substrate 2) existing around the antenna 1.

In addition, the length of the part from the center A of the edge | side used as the boundary with the 4th strip | belt-shaped part 121 to the one end point B of the edge on the opposite side to the 4th strip | belt-shaped part 121 among the outer periphery of the protrusion part 122, and protrusion. Of the outer periphery of the portion 122, a portion from the center A of the side that becomes the boundary with the fourth belt-shaped portion 121 to the other end point C on the opposite side of the fourth belt-shaped portion 121 (portion along the alternate long and short dash line in FIG. 1) When the lengths are different, the longer one may be set to a quarter or more of the effective wavelength c / (f × ε ^1/2 ) of the electromagnetic wave having the frequency f.

In the embodiment shown in FIG. 1, the operating band is an 800 MHz band (698 MHz or more and 960 MHz or less) and a frequency band for LTE on the higher frequency side. That is, a frequency band including f = 698 MHz as a lower limit is set as an operation band. When the relative dielectric constant ε of the dielectric substrate 2 is 3.3, the effective wavelength c / (f × ε ^1/2 ) of the electromagnetic wave having the frequency f = 698 MH is 236 mm. Therefore, the length of the fourth strip conductor 121 may be set to 236/2 = 118 mm or more. In the embodiment shown in FIG. 1, the length of the fourth strip conductor 121 is set to about 124 mm. On the other hand, of the outer periphery of the protrusion 122, the length of the portion from the center A of the side serving as the boundary with the fourth strip 121 to the end point B of the end opposite to the fourth strip 121 is 236 / 4 = 59 mm or more may be set. In the embodiment shown in FIG. 1, a portion from the center A of the side that becomes the boundary with the fourth strip 121 to the end point B of the end opposite to the fourth strip 121 in the outer periphery of the protrusion 122. Is set to 59 mm.

  Further, in the antenna 1 according to the present embodiment, as shown in FIG. 1, a bell-shaped conductor obtained by rounding two rectangular corners wider than the fourth belt-shaped portion 121 is used as the protruding portion 122. ing. More specifically, two corners of a rectangle having a length of 43.1 mm / width of 30 mm are respectively divided into a quadrant ellipse 122a having a minor axis radius of 6.1 mm / major axis radius of 15.6 mm and a minor axis radius of 5.9 mm / A bell-shaped conductor obtained by replacing with a quarter ellipse 122b having a major axis radius of 15.6 mm is used. The projecting portion 122 is connected to one end side (the x-axis positive direction side in FIG. 1) of the fourth belt-like portion 121 via a side sandwiched between two rounded corners. As described above, by using a bell-shaped conductor obtained by rounding two corners of a rectangle wider than the fourth strip 121 as the protrusion 122, the operating band can be expanded to the high frequency side.

  Further, in the antenna 1 according to the present embodiment, as shown in FIG. 1, one end side of the fourth belt-shaped portion 121 (on the x-axis positive direction side in FIG. 1) and two rounded portions of the projecting portion 122. A rectangular conductor piece 122c having this side as a long side is interposed between the side between the sides. When the length (width) of the short side of the conductor piece 122c is changed, the size of the gap between the first planar strip 11 and the protruding portion 122 changes, and as a result, the first planar strip 11 and the protruding portion are projected. The magnitude of capacitive coupling with the part 122 changes, and as a result, the impedance of the antenna 1 changes. That is, the impedance of the antenna 1 and the impedance of the coaxial cable can be matched only by changing the length of the short side of the conductor piece 122c.

  In the embodiment shown in FIG. 1, (1) a rectangular conductor piece 122c having a short side of 1 mm is added to a side sandwiched between two rounded corners of the protrusion 122, and (2) the first Rectangular conductor pieces 111c and 112c each having a short side of 1 mm are added to the end sides of the belt-like portion 111 and the second belt-like portion 112, respectively. Thereby, the size of the gap between the first planar conductor and the protruding portion 122 becomes 0.4 mm, and as a result, the impedance of the antenna 1 becomes 50Ω.

  Further, in the antenna 1 according to the present embodiment, as shown in FIG. 1, the first strip 111 is disposed farther from the second strip 112 on the other side (the x-axis positive direction side in FIG. 1) ( An extension 111b extending from the end of the y-axis negative direction side in FIG. 1 in the direction away from the third strip 113 (in the x-axis positive direction in FIG. 1) is added. The extension portion 111 b is a strip-shaped conductor that is narrower than the first strip-shaped portion 111. In the embodiment shown in FIG. 1, the length of the extension 111b is 10 mm, and the width of the extension 111b is 1.5 mm. Thus, by physically making the length of the first belt-like portion 111 and the length of the second belt-like portion 112 different, two resonance points can be formed in the vicinity of the lower limit of the operation band. The band can be expanded to the low frequency side.

[Example of antenna mounting]
Next, an implementation example of the antenna 1 will be described with reference to FIG.

  FIG. 2A is a perspective view of the automobile 5. A plastic decorative plate 50 is mounted on the outside of the pillar (a “structure” in the claims) in front of the rear door of the automobile 5. In this mounting example, the antenna 1 is built in the decorative plate 50.

  FIG. 2B is a plan view of the decorative board 50. FIG. 2C is a cross-sectional view showing an A-A ′ cross section of the decorative board 50.

  As shown in FIG. 2 (b), the decorative board 50 includes a plate-like main portion 51 having a trapezoidal shape when viewed from the outside of the vehicle and a plate-like extension portion having a rectangular shape when viewed from the outside of the vehicle. 52. The extension part 52 extends downward from the rear of the lower end of the main part 51 and is housed inside the door body together with the lower end of the main part 51. The antenna substrate 3 including the antenna 1 and the dielectric substrate 2 is embedded in the main part 51 of the decorative board 50 as shown in FIG.

  As shown in FIG. 2 (c), the surface of the decorative plate 50 (surface on the vehicle outer side) is flat. On the other hand, as shown in FIG. 2C, projecting portions 53 and 54 having an L-shaped cross section opened rearward are formed on the back surface (the vehicle inner surface) of the decorative plate 50. The protrusion 53 formed on the front edge of the back surface of the decorative plate 50 is used to embrace the metal plate 60 constituting the pillar from the front when the decorative plate 50 is attached to the pillar. On the other hand, the protruding portion 54 formed at the rear rear edge of the decorative plate 50 is used to accommodate the glass run channel 70.

  As shown in FIG. 2C, the metal plate 60 to which the decorative plate 50 is attached includes a first flat surface portion 60a, a second flat surface portion 60b, and an inclined portion 60c, and is adjacent to each other via the inclined portion 60c. There is a step between the first flat surface portion 60a and the second flat surface portion 60b. For this reason, as shown in FIGS. 2B and 2C, the decorative plate 50 includes a region A facing the first flat surface portion 60a, that is, a region A1 adjacent to the metal plate 60, and a second There will be a region A2 facing the flat portion 60b, that is, a region A2 separated from the metal plate 60.

  What should be noted in this mounting example is that the first belt-like portion 111 faces the first flat surface portion 60a and the inclined portion 60c, and the second belt-like portion 112 and the fourth belt-like portion 121 face the second flat surface portion 60b. As described above, the antenna 1 is arranged.

  By employ | adopting said arrangement | positioning, the distance from the 1st strip | belt-shaped part 111 to the metal plate 60 and the distance from the 2nd strip | belt-shaped part 112 to the metal plate 60 can be varied. That is, the effective length of the first belt-like portion 111 and the effective length of the second belt-like portion 112 can be made different. As a result, the operating band can be expanded to the low frequency side, as in the case where the length of the first belt-like portion 111 and the length of the second belt-like portion 112 are physically different. Moreover, the 4th strip | belt-shaped part 121 can be spaced apart from the metal plate 60 by employ | adopting said arrangement | positioning. Thereby, it is possible to avoid a decrease in gain in the vicinity of the lower limit of the operating band that may occur when the metal plate 60 is close to the fourth strip-shaped conductor 121.

[Characteristics of antenna]
Next, the characteristics of the antenna 1 will be described with reference to FIGS.

  FIG. 3 is a graph showing frequency characteristics of VSRW (chain line) and gain (solid line). FIG. 4 is a graph showing a radiation pattern on the zx plane (see FIG. 1) in each frequency band. 4, (a) shows a radiation pattern in a band from 698 MHz to 960 MHz, (b) shows a radiation pattern in a band from 1427 MHz to 1790 MHz, and (c) in a band from 1870 MHz to 2140 MHz. A radiation pattern is shown, (d) shows the radiation pattern in the band of 2170 MHz or more and 2500 MHz or less. These graphs are obtained in a state where the antenna 1 formed on the dielectric substrate 2 is arranged in free space.

  As shown in FIG. 3, the VSWR of the antenna 1 is a sufficiently small value (3 or less) in the 800 Mz band and the frequency band for LTE on the higher frequency side. Further, the gain of the antenna 1 is a sufficiently large value (−5 dBi or more) in the 800 Mz band and the frequency band for LTE on the higher frequency side.

  Further, as shown in FIG. 4, the directivity of the antenna 1 is sufficient in each of a band from 698 MHz to 960 MHz, a band from 1427 MHz to 1790 MHz, a band from 1870 MHz to 2140 MHz, and a band from 2170 MHz to 2500 MHz. Becomes smaller.

  Next, the characteristics of the antenna 1 in the mounting example shown in FIG. 2 will be described with reference to FIGS.

  FIG. 5 is a graph showing frequency characteristics of VSRW (dashed line) and gain (solid line). FIG. 6 is a graph showing a radiation pattern on the zx plane (see FIG. 1) in each frequency band. In FIG. 6, (a) shows a radiation pattern in a band from 698 MHz to 960 MHz, (b) shows a radiation pattern in a band from 1427 MHz to 1790 MHz, and (c) in a band from 1870 MHz to 2140 MHz. A radiation pattern is shown, (d) shows the radiation pattern in the band of 2170 MHz or more and 2500 MHz or less. These graphs are obtained in a state where the antenna 1 formed on the dielectric substrate 2 is built in the decorative board 50 attached to the pillar.

  As shown in FIG. 5, the VSWR of the antenna 1 is a sufficiently small value (3 or less) in the 800 Mz band and in the frequency band for LTE on the higher frequency side. Further, the gain of the antenna 1 is a sufficiently large value (−6 dBi or more) in the 800 Mz band and the frequency band for LTE on the higher frequency side.

  Further, as shown in FIG. 6, the directivity of the antenna 1 in the range from the zenith direction (x-axis positive direction) to the horizontal direction (z-axis positive direction) in the half space outside the vehicle is 698 MHz or more and 960 MHz or less. Each of the band, the band from 1427 MHz to 1790 MHz, the band from 1870 MHz to 2140 MHz, and the band from 2170 MHz to 2500 MHz are sufficiently small.

[Additional Notes]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The present invention can be suitably used as an antenna for wireless communication using a plurality of frequency bands, for example, an antenna for LTE.

DESCRIPTION OF SYMBOLS 1 Antenna 11 1st planar conductor 111 1st strip | belt-shaped part 111b extension part 112 2nd strip | belt-shaped part 113 3rd strip | belt-shaped part 12 2nd planar conductor 121 4th strip | belt-shaped part 122 Protruding part 122c Conductor piece 2 Dielectric substrate 3 Antenna substrate 60 metal plate 60a first plane part 60b second plane part

Claims (7)

An antenna comprising a first planar conductor and a second planar conductor,
The first planar conductor is disposed perpendicular to the first strip, the second strip disposed in parallel with the first strip, the first strip and the second strip, and Including a first belt-shaped portion and a third belt-shaped portion that connects one end sides of the second belt-shaped portion;
The second planar conductor is disposed in a region sandwiched between the first strip portion and the second strip portion, and is disposed in parallel with the first strip portion and the second strip portion. A projecting portion disposed outside the region sandwiched between the first belt-shaped portion and the second belt-shaped portion, and connected to the fourth belt-shaped portion,
A feeding point is provided at an end portion of the third belt-shaped portion and the fourth belt-shaped portion facing the third belt-shaped portion.
An antenna characterized by that. The length of the fourth band-shaped portion is at least one half of the effective wavelength of the electromagnetic wave having the lower limit frequency of the predetermined frequency band,
Of the outer periphery of the protruding portion, the length of the portion from the center of the side that becomes the boundary with the fourth belt-like portion to one end point of the end opposite to the fourth belt-like portion is the lower limit frequency. More than a quarter of the effective wavelength of the electromagnetic wave having,
The antenna according to claim 1. The protruding portion is a bell shape obtained by rounding two corners of a rectangle, and a side sandwiched between the two corners is connected to the fourth belt-shaped portion.
The antenna according to claim 1 or 2. The protruding portion is connected to the fourth belt-like portion through a rectangular conductor piece having a side between the two corners as a long side.
The antenna according to claim 3. The first band-shaped portion extends from the end farther from the second band-shaped portion on the other side opposite to the one end side and extends away from the third band-shaped portion. And a strip-shaped extension narrower than the first strip is added.
The antenna according to any one of claims 1 to 4. A structure comprising the antenna according to any one of claims 1 to 4 and a metal plate,
The metal plate includes a first plane part and a second plane part, and there is a step between the first plane part and the second plane part,
The antenna is disposed such that the first belt-like portion faces the first flat surface portion of the metal plate, and the second belt-like portion faces the second flat surface portion of the metal plate,
The distance from the second strip portion to the metal plate is longer than the distance from the first strip portion to the metal plate,
A structure characterized by that. The antenna has the first belt-like portion facing the first flat surface portion of the metal plate, and the second belt-like portion and the fourth belt-like portion facing the second flat surface portion of the metal plate. Arranged,
The structure according to claim 6.

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