JP5232577B2 - Broadband antenna - Google Patents

Description

  The present invention relates to a broadband antenna used for terrestrial broadcast waves and communication, for example.

  Terrestrial digital (television) broadcasting (ISDB-T: Integrated Services Digital Broadcasting-Terrestrial) uses radio waves in the UHF band, and the frequency band is 470 to 770 MHz (13 to 62 channels). In addition, mobile phones, terrestrial digital broadcasts, terrestrial digital 1 SEG broadcasts (1 seg broadcasts), etc. are retransmitted in buildings and underground malls, and there is a demand for wider bandwidth as receiving antennas.

  As a broadband antenna for receiving UHF band radio waves, a dipole element made of a substantially rectangular metal plate is arranged in a planar shape with a predetermined interval (see, for example, Patent Document 1).

When the antenna element of the dipole antenna is plate-shaped as described above, each antenna element that is a conductor is held by a holding body made of an insulating member in the central portion. And the feeding point is provided in the edge part which each antenna element hold | maintained at the said holding body opposes. A coaxial cable is connected to the feeding point and led to the UHF receiver.
JP 2005-244926 A

  In the UHF band receiving antenna, two plate-like conductors are necessary as components constituting the radiating element. Further, when the plate-like conductor as the antenna element is held by the holding body made of the insulating member, it is difficult to obtain a sufficient support strength structurally at the end portion of the plate-like conductor. Further, the ratio band of the antenna below VSWR 2.5 is about 50%, and it is difficult to cope with the case where a wider band is desired. Further, the overall length of the antenna including the antenna elements and the holding body needs to be about 0.5λa, and it is difficult to reduce the size.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a wide-band antenna that can be reduced in cost, downsized, and widened with a simple configuration.

A broadband antenna according to a first aspect of the present invention is a radiating element formed in a substantially rectangular shape by a plate-like conductive member, a substantially U-shaped slit provided from one long side of the radiating element toward the inside, A power supply portion provided in the vicinity of the first bent portion of the slit ,
The slit opens at one end located on the one long side, is perpendicular to the long side from the opening position, is bent along the other long side facing the long side, and further, the long side Extending to a terminal end provided in the vicinity, the length from the power supply unit to the terminal end is formed longer than the length from the opening end to the power supply unit, and the long side of the radiating element is the opening end of the slit and forms a straight line in the vicinity of the end position in the longitudinal direction of the polarization plane of the radiating element, characterized in that it have a shape of a directivity of approximately 8 to be maximum in a direction perpendicular to the plane of the radiating element .
A second invention is the broadband antenna according to the first invention, wherein the slit opens at an end located at a center side of the one long side, and the first bent portion is opposite to the center side. The radiating element is characterized in that the height in the short side direction is set to about 0.3 to 0.6 times the full length .
A third invention is the broadband antenna according to the first invention or the second invention, wherein the slit is located at a position of about 0.094λa (λa is a wavelength of the lower end frequency to be used) from the short side of the one long side. The radiation element has a length of about 0.15λa from the power feeding portion to the end, and the radiating element has a total length of about 0.35λa and is configured to be flat with a single member. .
A fourth invention is the wideband antenna according to the first invention, wherein the slit is opened at an end located at the center of the one long side, and about 0.15 λa (λa is used from the feed section to the end) The width of the slit is set to a constant value of about 0.008 λa from the opening end to the end, and the radiating element has a total length of about 0.35 λa and a height. It is characterized by being set to about 0.3 to 0.6 times the total length.
According to a fifth invention, in the wideband antenna according to the first invention, a slit in the same direction as the short side is formed in the vicinity of one short side of the radiating element, and the slit is formed at the center of the slit. The slit provided with a wavelength shortening part formed with a notch that opens on a short side, and the slit provided with the power feeding part is such that the end is on the short side and the opening end is on the opposite side to the short side. The width of the slit is wider than other portions from the last bent portion to the end.
A sixth invention is the broadband antenna according to any one of the second to fourth inventions, wherein the slit opens at an end located at the center of the one long side, and is about 0 from the power feeding unit to the terminal. .Λλa (λa is the wavelength of the lower end frequency to be used), and the radiating element of the four corners, the corner closest to the last bent portion of the slit is cut into a rectangle, and the slit Is provided with a capacitance adjusting section formed by expanding the width of the slit in the vicinity of the power feeding section.
A seventh invention is the broadband antenna according to the first invention, wherein the slit is disposed such that the end is on the short side and the opening end is on the side opposite to the short side, and the width of the slit is Between the last bent part and the terminal end, it is formed wider than the other part, and the radiating element has a folded part formed by folding the vicinity of both short sides thereof into a substantially U-shape. Of the two end portions, the end portion closest to the power feeding is closed.
An eighth invention is the broadband antenna according to any one of the first to fourth inventions, wherein the broadband antenna is attached to an electronic device, and the radiating element is provided from the opening end of the slit. The region of the radiating element divided by the first bent portion and the region opposite to the bending direction of the first bent portion is integrated with the metal case serving as the ground in the electronic device. Features.

  According to the present invention, it can be constituted by a single conductor member, and cost and size can be reduced. In addition, the band can be widened with a simple configuration, and high performance can be achieved. Furthermore, the feeding impedance can be set to a value of several tens of ohms and can be matched with the characteristic impedance of the coaxial cable without using the impedance matching circuit.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a front view showing a configuration of a wideband antenna 10A according to the first embodiment of the present invention.

  In FIG. 1, 11 is a holding substrate formed in a rectangular shape by an insulating material, and a rectangular radiating element 12 is mounted or formed on the front side thereof. As the radiating element 12, for example, a metal foil, a metal plate, or a film-like element is used, and the thickness is not particularly limited as long as it is a conductor.

  The radiating element 12 is set to have a total length (lateral width) La of about 0.35λa and a height Lb of about 0.11λa that is about 0.3 to 0.6 times the total length. Λa is the wavelength of the lower end frequency in the used frequency band.

The radiating element 12 is provided with a substantially U-shaped slit 13 in the vicinity of one end, for example, the right end in the figure, to form a radiating portion 14a, and the left side of the slit 13 serves as a (-) region 14b. The lateral width Lc of the radiating portion 14a is set to about 0.094λa, and the width d of the slit 13 is set to about 0.008λa. The slit 13 has an open upper end located on the center side, is provided downward from the opening position, and is bent along the lower side of the radiating element 12 to be formed in a substantially U-shape. The end of the slit 13 is provided in the vicinity of the upper side of the radiating element 12.

Further, the radiating element 12 is provided with a power feeding portion 15 in the vicinity of the first bent portion of the slit 13, for example. In this case, the power feeding unit 15 is provided with power feeding terminals 15a and 15b on both sides of the slit 13, and feeds the power feeding terminal 15a on the radiation unit 14a side with (+) power feeding and the other power feeding terminal 15b with (-) power feeding. The slit 13 is set to have a length from the power supply unit 15 to the tip of about 0.15λa .

  In the broadband antenna 10A configured as described above, the radiating portion 14a has substantially the same function as the monopole antenna, and when the power is fed from the feeding portion 15 provided in the vicinity of the first bent portion of the slit 13, Radio waves are radiated from the antenna 10A. At this time, the radio wave is radiated from the vicinity of the end of the slit 13.

  The broadband antenna 10A has a lower end frequency of 460 MHz and a VSWR of 2.5 or less, and the VSWR characteristics at this time are shown in FIG.

  The VSWR characteristic (characteristic impedance 75Ω) shown in FIG. 2 is VSWR 2.5 or lower in the range of 460 MHz to 1200 MHz, and a specific band of about 89% is obtained at VSWR 2.5 or lower.

  FIG. 3 shows the horizontal polarization horizontal plane directivity at 470 MHz of the broadband antenna 10A, which has a substantially 8-shaped directivity.

  The broadband antenna 10A has a very simple configuration in which a slit 13 is provided in a rectangular radiating element 12 to form a radiating portion 14a, and can be manufactured at low cost. Further, the radiating element 12 has a total length La of about 0.35 λa and a height Lb of about 0.11 λa, and is very small, and a good VSWR characteristic can be obtained over a wide band of 460 MHz to 1200 MHz. Furthermore, the feeding impedance can be set to a value of several tens of ohms and can be matched with the characteristic impedance of the coaxial cable without using an impedance matching circuit.

  In the above embodiment, the case where the radiating element 12 is provided on the holding substrate 11 has been described. However, the holding substrate 11 can be omitted when the shape can be held by the radiating element 12 itself.

  In the above embodiment, the case where the width Ld of the slit 13 is set to about 0.008 λa has been described, but it is needless to say that other values can be adjusted without departing from the gist of the present invention. Further, even if the width of the slit 13 is not constant, the effect of the present invention can be obtained even with a slit whose width gradually increases, for example.

(Second Embodiment)
Next, a broadband antenna according to a second embodiment of the present invention will be described.

  FIG. 4 is a front view showing a configuration of a wideband antenna 10B according to the second embodiment of the present invention.

  In the wideband antenna 10B according to the second embodiment, in the wideband antenna 10A according to the first embodiment, the slit 13 is moved to the center side of the radiating element 12, and the lateral width Lc of the radiating portion 14a is set to about 0.175λa. The other dimensions are the same as those of the first embodiment. Other configurations are the same as those of the broadband antenna 10A according to the first embodiment, and thus the same parts are denoted by the same reference numerals and detailed description thereof is omitted.

  In the broadband antenna 10B according to the second embodiment, VSWR3 or lower is set at a lower end frequency of 450 MHz, and the VSWR characteristics at this time are shown in FIG.

  The VSWR characteristic (characteristic impedance 75Ω) shown in FIG. 5 is VSWR3 or lower in the range of 450 MHz to 1500 MHz, and a ratio band of about 107% is obtained below VSWR3.

  In the broadband antenna 10B according to the second embodiment, the cost can be reduced, the size can be reduced, and the bandwidth can be reduced with a simple configuration as in the first embodiment, and the coaxial cable can be reduced without using the impedance matching circuit. Can be matched with characteristic impedance.

(Third embodiment)
Next, a broadband antenna according to a third embodiment of the present invention will be described.

  FIG. 6 is a front view showing a configuration of a broadband antenna 10C according to the third embodiment of the present invention.

  In the broadband antenna 10C according to the third embodiment, in the broadband antenna 10B according to the second embodiment, the slit 13 is further moved to the left end side, and the lateral width Lc of the radiating portion 14a is set to about 0.219λa. . Moreover, the slit 13 formed in a substantially U-shape forms the width d1 of the front end side slit 13b wider than the width d of the opening side slit 13a. For example, the width d of the opening side slit 13a is set to about 0.008λa, and the width d1 of the tip side slit 13b is set to about 0.05λa.

  Moreover, the wavelength shortening part 21 is provided in the radiation | emission part 14a of the radiation | emission element 12, for example in the vicinity of the right edge. The wavelength shortening portion 21 is provided with a vertical slit 22 in the vicinity of the right edge of the radiating portion 14 a, for example, and a notch 23 is provided at the center of the slit 22.

  By providing the notch 23 in the slit 22 as described above, the reactance can be corrected and the wavelength can be shortened. By performing the wavelength shortening as described above, the frequency band can be moved in the lower frequency direction.

  In the broadband antenna 10C according to the third embodiment, the total length La of the radiating element 12 is set to about 0.345λa, and the height Lb is set to about 0.19λa. Since other configurations are the same as those of the wideband antenna 10B according to the second embodiment, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the broadband antenna 10C according to the third embodiment, VSWR2 or lower is set at the lower end frequency of 470 MHz, and the VSWR characteristics at this time are shown in FIG.

  The VSWR characteristic (characteristic impedance 75Ω) shown in FIG. 7 is equal to or lower than VSWR2 in the range of 470 MHz to 850 MHz, and a ratio band of about 57% is obtained below VSWR2.

  Also in the broadband antenna 10C according to the third embodiment, the cost can be reduced, the size can be reduced, and the bandwidth can be increased with a simple configuration as in the above embodiments, and the coaxial cable can be reduced without using an impedance matching circuit. Can be matched with characteristic impedance.

(Fourth embodiment)
Next, a broadband antenna according to a fourth embodiment of the present invention will be described.

  FIG. 8 is a front view showing a configuration of a broadband antenna 10D according to the fourth embodiment of the present invention.

  The wideband antenna 10D according to the fourth embodiment is, for example, the same as the wideband antenna 10B according to the second embodiment, in which a notch 25 is provided in a part of the radiating portion 14a, for example, in the lower right portion in the figure. In FIG. 8, a capacity adjustment unit 26 is provided in the vicinity of the power supply unit 15 with respect to the slit 13 so that the capacity of the power supply unit 15 can be adjusted. The capacity adjustment unit 26 can variably set the capacity by changing the slit shape in the vicinity of the power supply unit 15, thereby adjusting the power supply impedance. In the fourth embodiment, the radiating element 12 is formed of a metal plate, and the holding substrate 11 is omitted because the radiating element 12 itself can hold the shape.

  Since other configurations are the same as those of the wideband antenna 10B according to the second embodiment, the same portions are denoted by the same reference numerals, and detailed description thereof is omitted.

  Even if the notch portion 25 is provided in the radiating portion 14a as described above, the antenna characteristics are not greatly affected, and substantially the same characteristics can be obtained.

(Fifth embodiment)
Next, a broadband antenna according to a fifth embodiment of the present invention will be described.

  FIG. 9 shows a configuration of a wideband antenna 10E according to a fifth embodiment of the present invention, where (a) is a front view and (b) is a bottom view. FIG. 10 is a perspective view showing the configuration of the broadband antenna 10E according to the embodiment.

  The wideband antenna 10E according to the fifth embodiment has a three-dimensional configuration in the wideband antenna 10C according to the third embodiment, in which both side portions of the radiating element 12 are folded back to the front side, for example, and folded portions 31 and 32 are provided. This is a reduction in size. In the broadband antenna 10E according to this embodiment, the radiating element 12 is formed of a metal plate, the holding substrate 11 is omitted as a configuration that can hold the shape by the radiating element 12 itself, and the wavelength reduction shown in the third embodiment is performed. The part 21 is omitted.

  In the fifth embodiment, in the folded portion 31 on the left end side in the figure, the end portion of the radiating element 12 is folded back into a substantially U shape, and the lower end portion thereof is closed by a member 31a.

  Further, in the folded portion 32 on the right end side in the figure, the end portion of the radiating element 12 is formed in a substantially U-shape, and the upper and lower end portions thereof are kept open.

  The broadband antenna 10E has a lateral width La1 of about 0.251λa and a height Lb1 of about 0.13λa.

  In the wideband antenna 10E according to the fifth embodiment, the lateral width La1 can be reduced by about 0.1λa from 0.345λa to 0.251λa and the height Lb1 can be reduced to 0.1 mm compared to the wideband antenna 10C according to the third embodiment. The size can be reduced by about 0.06λa from 19λa to 0.13λa. Also, the wideband antenna 10E according to the fifth embodiment can obtain wideband antenna characteristics substantially equivalent to the wideband antenna 10C according to the third embodiment.

(Sixth embodiment)
Next, a broadband antenna according to a sixth embodiment of the present invention will be described.

  In the sixth embodiment, when the broadband antenna 10B according to each embodiment, for example, the second embodiment is used by being mounted on the equipment casing 41 of an electronic device as shown in FIG. The region 14b is integrated with the ground of the device casing 41 to reduce the antenna space.

  FIG. 11 shows an example in which the wideband antenna 10B (see FIG. 4) according to the second embodiment of the present invention is used by being mounted on an equipment casing 41 of an electronic device, wherein (a) is a front view, b) is a side view.

  In this embodiment, when the broadband antenna 10B is attached to the device casing 41, the (−) region 14b of the radiating element 12 is integrated with the metal case (earth) of the device casing 41, and the device casing 41 is integrated with the radiating element 12. This is used as the (−) region 14b.

  By integrating the (−) region 14b of the radiating element 12 with the metal case of the device housing 41 as described above, the broadband antenna 10B has the (−) region 14b of the radiating element 12 positioned on the left side of the slit 13. There is no need to provide the antenna, and the installation area of the antenna can be halved, and the antenna can be easily installed even in a narrow space.

  In each of the above embodiments, the case where the antenna cover is not provided has been described. However, the broadband antenna shown in each embodiment may be covered with a cover made of an insulator.

  Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

It is a front view which shows the structure of the wideband antenna which concerns on 1st Embodiment of this invention. It is a VSWR characteristic view of the wideband antenna according to the embodiment. It is a figure which shows the horizontal polarization horizontal plane directivity in 470 MHz of the wideband antenna which concerns on the embodiment. It is a front view which shows the structure of the wideband antenna which concerns on 2nd Embodiment of this invention. It is a VSWR characteristic view of the wideband antenna according to the embodiment. It is a front view which shows the structure of the wideband antenna which concerns on 3rd Embodiment of this invention. It is a VSWR characteristic view of the wideband antenna according to the embodiment. It is a front view which shows the structure of the wideband antenna which concerns on 4th Embodiment of this invention. The structure of the wideband antenna which concerns on 5th Embodiment of this invention is shown, (a) is a front view, (b) is a bottom view. It is a perspective view which shows the structure of the wideband antenna which concerns on the same embodiment. The state which mounted | wore the apparatus housing | casing with the wideband antenna which concerns on embodiment of this invention is shown, (a) is a front view, (b) is a side view.

Explanation of symbols

  10A to 10E: Broadband antenna according to first to fifth embodiments, 11: holding substrate, 12 ... radiating element, 13 ... slit, 13a ... opening side slit, 13b ... tip side slit, 14a ... radiating portion, 14b ( -) Region, 15 ... feeding part, 15a, 15b ... feeding terminal, 21 ... wavelength shortening part, 22 ... slit, 25 ... notch part, 26 ... capacity adjusting part, 31, 32 ... folding part, 31a ... member, 41 ... equipment housing.

Claims (8)

A radiating element formed in a substantially rectangular shape by a plate-like conductive member, a substantially U-shaped slit provided from one long side to the inside of the radiating element, and a first bent portion in the vicinity of the slit. A power supply unit ,
The slit opens at one end located on the one long side, is perpendicular to the long side from the opening position, is bent along the other long side facing the long side, and further, the long side Extending to the terminal provided in the vicinity, forming the length from the power feeding part to the terminal longer than the length from the opening end to the power feeding part,
The long side of the radiating element is linear in the vicinity of the opening end and end position of the slit,
In the longitudinal direction of the polarization plane of the radiating element, the antenna, characterized in that the have a shape of a directivity of approximately 8 to be maximum in a direction perpendicular to the plane of the radiating element. The slit opens at the end located on the center side of the one long side, and bends toward the side opposite to the center side at the first bent portion,
The broadband antenna according to claim 1, wherein the radiating element has a height in a short side direction set to about 0.3 to 0.6 times a full length . The slit opens at a position of about 0.094λa (λa is the wavelength of the lower end frequency of use) on the one long side, and has a length of about 0.15λa from the power feeding unit to the terminal end,
The broadband antenna according to claim 1, wherein the radiating element has a total length of about 0.35 λa and is configured to be flat with a single member . The slit is opened at an end located at the center of the one long side, and has a length of about 0.15λa (λa is a wavelength of a used lower end frequency) from the power feeding unit to the end, and the width of the slit is From the opening end to the end, set to a constant about 0.008λa,
The broadband antenna according to claim 1, wherein the radiating element has a total length of about 0.35λa and a height of about 0.3 to 0.6 times the total length. The broadband antenna further includes a slit formed in the same direction as the short side in the vicinity of one short side of the radiating element, and a notch opening in the short side is formed in the center of the slit. It has a wavelength shortening section,
The slit provided with the power feeding portion is arranged so that the end is on the short side and the opening end is on the side opposite to the short side, and the width of the slit is between the last bent portion and the end. The wideband antenna according to claim 1, wherein the wideband antenna is formed wider than other portions. The slit opens at an end located at the center of the one long side, and has a length of about 0.15 λa (λa is a wavelength of a lower end frequency to be used) from the power feeding unit to the end.
Of the four corners of the radiating element, the corner closest to the last bent portion of the slit is cut into a rectangle,
5. The broadband antenna according to claim 2, wherein the slit includes a capacitance adjusting unit formed by expanding a width of the slit near the power feeding unit. 6. The slit is arranged so that the end is on the short side and the open end is on the side opposite to the short side, and the width of the slit is between the last bent part and the end, compared to other parts. Widely formed,
The radiating element has a folded portion formed in a substantially U shape by folding back near both short sides, and an end portion closest to the power feeding is closed among both ends of both folded portions. The broadband antenna according to claim 1. The broadband antenna is attached to an electronic device,
The radiating element is a region of the radiating element that is divided into two by the first bent portion from the opening end of the slit, and a region opposite to a bending direction of the first bent portion is grounded by the electronic device. The broadband antenna according to any one of claims 1 to 4, wherein the broadband antenna is integrated with a metal case.

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