JP2006060561A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wide-band antenna having a wide directivity, small-sized and this structure and an adequate capability for a wavelength shortening. <P>SOLUTION: A plane antenna 1 comprises a plurality of flag elements 6 composed of a conductive material having a quadratic element 5 with a quadratic shape, a closed loop shape, and composed of the conductive material, a flag 6a with the quadratic shape and the closed loop shape, and a base end 6b which extends one side of a flag 6a. The antenna also comprises two radiant portions 3 (3a, 3b) which are the same shape and located on the same plane having a quadratic flag element 7 in which the quadratic element 5 and the flag element 6 are located on the same plane. The base end 6b of the flag element 6 is connected to the rim of the quadratic element 6. The flag element 6 is arranged axisymmetrically to the quadratic element 5. The antenna also comprises a feeding portion 4 located on the same plane as the radiant portions 3 having a pair of terminal portions 8 (8a, 8b). One terminal portion 8a is connected to at least one radiant portion 3a, and the other terminal portion 3b is connected to the other terminal portion 3b, and composed of the conductive material. An axisymmetric axis of each of the radiant portions 3a and 3b is arranged to extend in a different direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antenna, and more particularly to an antenna having broadband characteristics with respect to terrestrial waves, wide directivity, small and thin, and suitable for shortening the wavelength.

  In recent years, with the progress of radio wave utilization technology, the development of antennas has been diversified, and various devices such as a Yagi antenna, a rod antenna, a loop antenna, and a dipole antenna have already been developed and put into practical use. In particular, along with the progress of wireless devices and communication means, the development of antennas used in communication means for these new small devices has been made possible by the practical application of terrestrial digital television broadcasting, wireless mobile phones, mobile phones, IC tags, IC cards, etc. (For example, refer to Patent Document 1).

JP 2002-271130 A

  However, the antenna used in the above-described small device needs to be reduced in size and configured to be capable of transmitting and receiving radio waves in all directions with wide directivity. Many types of antennas have directivity in order to increase gain and performance, and in order to achieve omnidirectionality with such antennas, it is necessary to make a composite antenna having a plurality of antennas, There was a problem that miniaturization / reduction of the antenna could not be achieved.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an antenna having wide bandwidth, wide directivity, small and thin, and suitable for shortening the wavelength.

  In order to solve the above-described problems, an antenna according to the present invention includes a radiating element (for example, the square element 5 in the embodiment) having a closed loop shape and formed of a conductive material, a flag unit, and the flag unit. A plurality of flag elements formed of a conductive material having a base end protruding from the base, the radiating element and the flag element are located on the same plane, and the base end of the flag element is at the edge of the radiating element At least two radiations that are connected and have the same shape and having the radiation element arranged in line symmetry with respect to the radiation element (for example, the square flag element 7 in the embodiment) and located on the same plane. And a pair of terminal portions, one of the terminal portions is connected to at least one radiating portion, the other of the terminal portions is connected to the remaining radiating portion, Conductive And a feeding part formed of a material configured so that a line symmetry axis of each of the radiating portion extending in different directions.

  The antenna according to the present invention is configured so that each radiating section has two or more radiating flag elements arranged in line symmetry, and both ends of the radiating flag elements constituting the radiating section in the line symmetric axis direction are arranged. It is preferable to be electrically connected.

  At this time, it is desirable that the radiating element is formed in a square shape. Moreover, it is preferable that the flag part of the flag element is formed in a square shape and a closed loop shape, and the base end part is formed so as to extend by extending one side of the flag part.

  Moreover, it is preferable to have a loop element arranged on the same plane so as to surround the radiating part, and to be configured such that an end of the loop element is connected to a terminal of the power feeding part. At this time, a part of the loop element may be cut off.

  Moreover, it is preferable that the power feeding unit is configured to include a matching element that is formed in a square shape and a closed loop shape and has an impedance of a predetermined value. Furthermore, it is preferable that the power supply unit is configured to have a filter element that allows only a predetermined frequency to pass.

  Furthermore, the antenna according to the present invention has two radiating portions (for example, the first and second radiating portions 3a and 3b in the embodiment), and the symmetric axes of the radiating portions are different by 90 degrees. Preferably it is comprised. Or it is preferable that it has four radiation | emission parts (for example, the 1st-4th radiation | emission parts 23a-23d in embodiment), and the line symmetry axis of each radiation | emission part differs 90 degree | times.

  By configuring the antenna according to the present invention as described above, the antenna can be planarized and reduced in size, which is suitable for a small communication device. In addition, since the radiating section is composed of a radiating element composed of a radiating element and a plurality of flag elements connected to the radiating element in line symmetry, it is possible to widen the frequency band that can be transmitted and received by this antenna. In addition, the wavelength can be shortened. Furthermore, it is configured to have two or more of these radiating portions, and by configuring the line symmetry axis to extend in different directions, it is possible to widen the directivity of this antenna and transmit / receive radio waves in all directions. can do.

  In addition, by configuring the radiating portion by combining a plurality of radiating flag elements, the sensitivity can be improved and the directivity of this antenna can be made wider, so that transmission / reception of radio waves in all directions can be made possible. it can.

  In addition, by forming the radiating element that forms the radiating flag element in a square shape, or by forming the flag part of the flag element in a square shape and a closed loop shape, the optimal transmission / reception conditions can be set according to the frequency band, usage, etc. Can be set.

  Furthermore, the gain of this antenna can be improved by providing a loop element so as to surround the radiating portion. This loop element can be adjusted in gain and impedance by cutting a part thereof. Alternatively, by providing a matching element in the power feeding unit, it is possible to adjust the impedance of the antenna and to widen the frequency band in which transmission and reception can be performed.

  In the present invention, two radiating portions are provided so that their line symmetry axes are different from each other by 90 degrees, or four radiating portions are provided so that their line symmetry axes are different from each other by 90 degrees. By configuring the antenna according to the above, it is possible to effectively widen directivity and enable transmission / reception of radio waves in all directions.

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

  First, the first embodiment will be described with reference to FIG. The planar antenna 1 according to the first embodiment includes a substrate 2 made of a dielectric (insulator) and a conductive thin film (radiating portion 3) mounted on the plane of the substrate 2, that is, located on the same plane. And a power feeding unit 4).

  In the planar antenna 1 configured as above, the substrate 2 may be rigid or flexible, and the material thereof is not limited. For example, when the flexible substrate 2 is used, it can be mounted on a gently curved surface such as a windshield or rear glass of an automobile, or used for a flexible wireless IC card or the like.

  The radiating portion 3 is a square flag element including a square element 5 having a square shape and a closed loop shape, and a plurality of flag elements 6 arranged in line symmetry on the side of the square element 5. 7. At this time, the flag element 6 is composed of a flag portion 6a having a square shape and a closed loop shape, and a base end portion 6b extending from one side of the flag portion 6a. The base end portion 6 b extends so as to be orthogonal to the line symmetry axis X direction and is connected to the edge of the rectangular element 5.

  In this first embodiment, the radiating section 3 has two square flag elements 7 and is arranged so that the line symmetry axes thereof are parallel to each other, and the end in the direction of the line symmetry axis is electrically connected. Are connected to each other, and the entire radiation unit 3 is configured to be line symmetric about the line symmetry axis Y. The number of square flag elements 7 constituting the radiating portion 3 is not limited to two, and may be one or three or more. And in this 1st Example, the radiation | emission part 3 is comprised from the 1st radiation | emission part 3a and the 2nd radiation | emission part 3b from which the direction which the line symmetry axis Y extends differs 90 degree | times. The first radiating portion 3a and the second radiating portion 3b have the same shape.

  The power feeding unit 4 is formed of the same conductive material as that of the radiating unit 3, and is formed in a strip shape on the substrate 20 and a set of two terminal units 8 (8 a, 8 b) formed on the substrate 2. Thus, each of the terminal portions 8a, 8b and the line portion 9 (9a, 9b) connecting the first and second radiating portions 3a, 3b are configured. The terminal portion 8 is connected to a feeder line that connects the communication device and the planar antenna 1.

  Since the material of the conductive thin film forming the radiating portion 3 and the power feeding portion 4 is not limited, copper, aluminum, carbon, or the like can be applied. It is also possible to form using conductive ink. As a method for forming such a thin film, an etching method, a hot stamping (foil pressing) method, or the like can be applied. Also, a method of cutting a strip-shaped metal foil into a predetermined length and attaching it to the substrate 2 can be applied. it can. Furthermore, when a conductive ink is used, a printing method can be applied.

  In addition, in FIG. 1, although the case where the electroconductive thin film part (the radiation | emission part 3 and the electric power feeding part 4) was attached on the board | substrate 2 was demonstrated, when comprising a large sized antenna, a metal tube or a metal rod (some In this case, the shape of the conductive material forming the pattern of the radiating portion 3 and the feeding portion 4 can be sufficiently secured. Can omit the substrate 2 (the same applies to the following embodiments).

  In the planar antenna 1 having such a configuration, when an AC voltage in the radio frequency band is applied to the terminal portion 8 (8a, 8b) of the power feeding portion 4, the radiation portions 3a, 9a, 9b are connected via the line portion 9 (9a, 9b). This AC voltage is transmitted to 3b, and radio waves corresponding to the AC voltage are radiated from the radiation portions 3a and 3b. On the contrary, when a radio wave is irradiated on the planar antenna 1, an AC voltage can be taken out from the terminal portion 8 (8a, 8b) of the power feeding portion 4 according to the electromotive force generated in the radiating portions 3a, 3b.

  Now, the directivity of the planar antenna 1 according to the first embodiment will be described with reference to FIG. FIG. 2 (a) shows the directivity on the XY plane when viewed from the side with the line symmetry axis B of one radiating portion (3a or 3b) coincident with the Z axis, which is close to the figure 8. It has a circular directivity. On the other hand, FIG. 2B shows the directivity on the XZ plane when the radiating portion 3a (3b) is viewed from above, and power is supplied in the left and right (X-axis direction) and rearward (Z-axis direction). The directionality of the direction in which the portion 4 is connected) has a circular directivity close to an egg shape. For this reason, as shown in FIG. 1, by directing the axis of symmetry of the first radiating portion 3a and the second radiating portion 3b (Z-axis direction in FIG. 2) in different directions, a highly directional portion is directed in different directions. On the other hand, by making the planar antenna 1 as a whole more circular, directivity can be widened (slow directivity can be obtained).

  As described above, the planar antenna 1 according to the first embodiment includes the rectangular portion 7 having the radiating portion 3 including the rectangular element 5 and the plurality of flag elements 6 connected to the rectangular element 5 in line symmetry. Therefore, the frequency band that can be transmitted / received by the planar antenna 1 can be widened (for example, radio waves of 10 MHz to 10 GHz can be transmitted / received), and the wavelength can be shortened. Further, by configuring the radiating unit 3 by combining a plurality of square flag elements 7, the sensitivity is improved and the directivity shown in FIG. 2 is made closer to a circle, that is, transmission / reception in all directions is possible. be able to.

  As described above, according to the planar antenna 1 according to the first embodiment, it is possible to realize an antenna having wide directivity, small and thin, and suitable for reduction. Moreover, the planar antenna 1 can easily cope with a wide band. Moreover, since this planar antenna 1 can be manufactured by a method similar to a printed wiring board (including a flexible printed wiring board), the planar antenna 1 can be formed in a partial region on the printed wiring board. . That is, the planar antenna 1 can be mounted on a part of the printed wiring board on which the transmission / reception circuit is mounted in the same manufacturing process. Therefore, the entire transmission / reception apparatus including the planar antenna 1 can be reduced in size, and the manufacturing process can be simplified and the manufacturing cost can be reduced.

  Further, since the planar antenna 1 according to the first embodiment is configured to be located on the same plane as a whole as shown in FIG. 1, the planar antenna 1 may be installed by bonding or the like at a predetermined location. Work can be facilitated. Further, the planar antenna 1 attached by bonding has no possibility of being damaged because there is no portion protruding to the outside.

  Next, the planar antenna 21 according to the second embodiment will be described with reference to FIG. The planar antenna 21 according to the second embodiment is a case where the number of the two radiation portions 3 (3a, 3b) of the planar antenna 1 according to the first embodiment is four. For this reason, the configuration of the square flag element 7 and the like described in the first embodiment is denoted by the same reference numerals and description thereof is omitted. In FIG. 3, a substrate formed of an insulator is omitted and not shown. In addition, each radiation | emission part 23 in this 2nd Example is the same shape as each radiation | emission part 3 in 1st Example.

  The radiating portion 23 of the planar antenna 21 is composed of four radiating portions including a first radiating portion 23a, a second radiating portion 23b, a third radiating portion 23c, and a fourth radiating portion 23d. The directions are arranged so as to be different by 90 degrees. In addition, one of the two line portions 9a and 9b constituting the power feeding portion 4 (9a) is connected to the first and second radiating portions 23a and 23b, and the other (9b) is the third and fourth radiating portions 23c. , 23d. Therefore, as in the first embodiment, when an AC voltage in the radio frequency band is applied to the terminal portions 8 a and 8 b of the power feeding unit 4, this AC is applied to the radiating units 23 a, 23 b, 23 c, and 23 d via the line unit 9. The voltage is transmitted, and radio waves corresponding to the AC voltage are radiated from the radiation portions 23a, 23b, 23c, and 23d. On the other hand, when the planar antenna 1 is irradiated with radio waves, an alternating voltage can be taken out from the terminal portions 8a and 8b of the power feeding unit 4 according to the electromotive force generated in the radiating portions 23a, 23b, 23c, and 23d. .

  Since the directivity of each of the radiating portions 23a, 23b, 23c, and 23d constituting the planar antenna 21 is as described with reference to FIG. 2 in the first embodiment, the direction in which the line symmetry axis extends in this way. By shifting 90 degrees by 90 degrees, the directivity becomes almost circular, and transmission / reception in all directions can be made possible. Other effects are the same as in the first embodiment.

  As described above, the planar antennas 1 and 21 according to the first and second embodiments are configured to have two or four radiating portions 3 and 23, and the direction in which the line symmetry axis extends is 90 degrees each. By configuring differently, directivity becomes close to a circle and transmission / reception is possible in all directions. Further, a third embodiment with improved sensitivity and the like will be described with reference to FIGS. . As in the case of the second embodiment, the components already described are denoted by the same reference numerals and detailed description thereof is omitted. In addition, a substrate formed of an insulator is not shown.

  FIG. 4 shows a loop element 10 attached to the planar antenna 1 according to the first embodiment on the same plane so as to surround the radiating portion 3 (3a, 3b) and a plurality of rectangular and closed loop matching elements. 11 is shown.

  The loop element 10 is attached so as to surround the front side (the direction in which the power feeding unit 4 is not connected) and the side of the radiation units 3a and 3b, and both ends thereof are respectively connected to the power feeding unit 4 (line portions 9a and 9b). It is connected. This loop element 10 has a function of improving the gain in the radiation portions 3a and 3b.

  On the other hand, the plurality of matching elements 11 are provided at a portion where the loop element 10 and the power feeding unit 4 are connected, and have a function of adjusting the impedance of the planar antenna 31 to a desired value (for example, a television set). When used for broadcast reception, the impedance is set to 75Ω). Further, the matching element 11 has a different size from the closed loop of the rectangular element 5 and the flag element 6 of the radiating portions 3a and 3b, so that the frequency band that can be transmitted and received by the planar antenna 31 can be expanded. For example, as shown in FIG. 4, the band can be widened to the lower frequency side by forming it larger than the square element 5 and the flag element 6.

  Thus, by providing the loop element 10 and the matching element 11, the gain of the planar antenna 31 can be improved and the frequency band can be widened. Also, the impedance of the planar antenna 31 can be adjusted to a desired value.

  FIG. 5 shows a loop antenna 10 mounted on the same plane so as to surround the radiating portion 23 (23a, 23b, 23c, 23d) and a rectangular and closed loop shape on the planar antenna 21 according to the second embodiment. A planar antenna 41 provided with a plurality of matching elements 11 is shown. Also in the planar antenna 41, the loop element 10 and the matching element 11 can improve the gain, widen the frequency band, and further adjust the impedance to a desired value.

  Further, like the planar antennas 31 'and 41' shown in FIGS. 6 and 7, a filter element 12 is provided at a connection portion between the loop element 10 (matching circuit 11) and the power feeding portion 4 (line portions 9a and 9b). Accordingly, it is possible to transmit and receive only the desired frequency band with the planar antennas 31 'and 41' while blocking unnecessary frequencies.

  As shown in FIGS. 6 and 7, the loop element 10 may be composed of a first loop element 10a and a second loop element 10b that are partially cut and connected to the line portions 9a and 9b, respectively. Is possible. Thus, by providing the gap 10 c in the loop element 10, it is possible to adjust the gain of the planar antennas 31 ′ and 41 ′ and to adjust the impedance. Further, in the case of the planar antennas 31 ′ and 41 ′ shown in FIGS. 6 and 7, when a coaxial cable is connected to the terminal portions 8 a and 8 b of the power feeding portion 4, the terminal portion 8 a directly connected to the radiating portions 3 and 23 is connected. The core wire of the coaxial cable is connected, and the shield wire of the coaxial cable is connected to the terminal portion 8 b connected to the radiation portions 3 and 23 via the filter element 12.

  In the first and second embodiments described above, the description has been given of the case where both the square element 5 and the flag portion 6a of the flag element 6 have a square shape and a closed loop shape, but the present invention is limited to this form. For example, the square element 5 may be circular, elliptical, polygonal, or square, and may be formed in a closed loop shape, and the flag portion 6a of the flag element 6 is circular or elliptical. It may be formed in a shape, polygon, or square shape. Moreover, this flag part 6a is not a closed loop shape, and the whole surface may be comprised with the electroconductive material.

It is a top view which shows the planar antenna which concerns on 1st Example. It is a figure which shows the directivity of a radiation | emission part, (a) is a figure which shows the directivity in XY plane, (b) is a figure which shows the directivity in XZ plane. It is a figure which shows the planar antenna which concerns on 2nd Example. It is a top view at the time of providing a loop element and a matching element in the planar antenna which concerns on 1st Example. It is a top view at the time of providing a loop element and a matching element in the planar antenna which concerns on 2nd Example. It is a top view at the time of providing a filter element further in the plane antenna concerning the 1st example. It is a top view at the time of providing a filter element further in the plane antenna concerning the 2nd example.

Explanation of symbols

1, 21, 31, 31 ', 41, 41' Planar antenna 3, 23 Radiation part 3a, 23a First radiation part 3b, 23b Second radiation part 23c Third radiation part 23d Fourth radiation part 4 Feeding part 5 Rectangular element (Radiation element)
6 Flag element 6a Flag part 6b Base end part 7 Square flag element (radiation flag element)
8 (8a, 8b) Terminal portion 10 (10a, 10b) Loop element 11 Matching element 12 Filter element

Claims (10)

A radiating element having a closed loop shape and formed of a conductive material; and a flag portion and a plurality of flag elements having a base end portion protruding from the flag portion and formed of a conductive material. The element and the flag element are located on the same plane, the base end of the flag element is connected to the edge of the radiating element, and the flag element is line-symmetrically arranged with respect to the radiating element At least two or more radiating portions having the same shape and having the radiating flag element and located on the same plane;
Located on the same plane as the radiating part, has a pair of terminal parts, one of the terminal parts is connected to at least one radiating part, the other of the terminal parts is connected to the remaining radiating part, A power feeding part formed of a conductive material,
An antenna, wherein the axis of line symmetry of each of the radiating portions extends in different directions. Each of the radiating portions is configured to have two or more of the radiating flag elements arranged in line symmetry,
2. The antenna according to claim 1, wherein both ends of the radiation flag element constituting the radiation portion are electrically connected to each other in the line symmetry axis direction.   The antenna according to claim 1, wherein the radiating element is formed in a square shape.   The flag part of the flag element is formed in a square shape and a closed loop shape, and the base end part is formed to extend by extending one side of the flag part. The antenna in any one of -3. A loop element disposed on the same plane so as to surround the radiation part;
The antenna according to any one of claims 1 to 4, wherein an end portion of the loop element is connected to each of the terminals of the feeding portion.   The antenna according to claim 5, wherein a part of the loop element is cut.   The antenna according to any one of claims 1 to 6, wherein the feeding portion is configured to have a matching element that is formed in a square shape and in a closed loop shape and has an impedance of a predetermined value. .   The antenna according to any one of claims 1 to 7, wherein the power feeding unit includes a filter element that allows only a predetermined frequency to pass therethrough.   The antenna according to any one of claims 1 to 8, wherein the antenna has two radiating portions, and each radiating portion has a line symmetry axis that is 90 degrees different from each other. The antenna according to claim 1, wherein the antenna has four radiating portions, and each radiating portion has a line symmetry axis that is different by 90 degrees.

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