JP5444540B2 - antenna - Google Patents

Description

  The present invention relates to an antenna, and more particularly to an antenna for transmitting or receiving horizontally polarized waves.

  Since radio waves for television broadcasting are often horizontally polarized, antennas for receiving horizontally polarized waves have been developed. An example of such an antenna is a dipole antenna. When a dipole antenna is used as a horizontally polarized wave receiving antenna, the length in the horizontal direction is required to be at least about half the resonance wavelength.

  In general, the shape of the antenna includes a vertical type in which the length in the vertical direction is larger than the length in the horizontal direction and a horizontal type in which the length in the horizontal direction is larger than the length in the vertical direction. An example of a vertical antenna is an antenna called hentena. Hentena is a type of loop antenna, with two long sides in the vertical direction (vertical direction) having a length that is ½ of the resonance wavelength of the antenna, and two short sides in the horizontal direction (horizontal direction). It is a rectangular antenna having a length of 1/6 of the wavelength.

  According to Japanese Patent Laid-Open No. 9-284028 (Patent Document 1), the conventional henna has a problem that the sensitivity tends to concentrate on a specific frequency. Patent Document 1 discloses a planar radiation antenna having the following structure as a henna capable of solving such problems. That is, the planar radiating antenna includes a rectangular frame member made of a conductive band-shaped metal having a length ratio of long side to short side of 2 to 3 to 1, a feeding point provided at a predetermined portion of the long side, It has a structure in which two conductive path plates provided so as to protrude to face each other at a predetermined portion inside the side are integrated. The rectangular frame member has a U-shaped cross section over the entire circumference. Further, the power supply box is connected to the two conductive path plates.

Japanese Patent Laid-Open No. 9-284028

  According to Patent Document 1, it is described that the antenna is excellent in high bandwidth. However, Patent Document 1 does not specifically describe the use frequency band of the antenna (hentena).

  An object of the present invention is to provide a vertical antenna having a wide use frequency band.

In summary, the present invention is an antenna, and includes a first loop antenna element, a second loop antenna element, and a power feeding unit for feeding power to the first and second loop antenna elements. The first loop antenna element includes first and second long-side conductors arranged to face each other, one end of the first long-side conductor and one end of the second long-side conductor facing each other, And a second short-side conductor connecting the other end of the first long-side conductor and the other end of the second long-side conductor facing each other. The second loop antenna element includes third and fourth long-side conductors arranged so as to face each other, one end of the third long-side conductor and one end of the fourth long-side conductor facing each other, And a fourth short-side conductor connecting the other end of the third long-side conductor and the other end of the fourth long-side conductor facing each other. The length of each of the first and second long-side conductors in the extending direction is approximately ½ of the resonance wavelength required for the first loop antenna element. The length in the extending direction of each of the first and second short-side conductors is approximately 1/6 of the resonance wavelength required for the first loop antenna element. The length in the extending direction of each of the third and fourth long-side conductors is approximately ½ of the resonance wavelength required for the second loop antenna element. The length of each of the third and fourth short-side conductors in the extending direction is approximately 1/6 of the resonance wavelength required for the second loop antenna element. The width of the two end portions of each of the first to fourth long-side conductors is larger than the width of the intermediate portion located between the two end portions. In the first and second loop antenna elements, the first short-side conductor and the third short-side conductor intersect each other at substantially right angles, and the second short-side conductor and the fourth short-side conductor are mutually They are arranged so as to intersect at substantially right angles. The antenna further includes first to fourth feed lines and first and second stubs. The first feeder line is located between the first end connected to the intermediate portion of the first long-side conductor, the opposite side of the first end, and between the first long-side conductor and the second long-side conductor. And a second end. The second feeder line is located between the first end connected to the intermediate portion of the second long-side conductor, the opposite side of the first end, and between the first long-side conductor and the second long-side conductor. And a second end. The third feeder line is located between the first end connected to the middle portion of the third long-side conductor, the opposite side of the first end, and between the third long-side conductor and the fourth long-side conductor. And a second end. The fourth feeder line is located between the first end connected to the middle portion of the fourth long-side conductor, the opposite side of the first end, and between the third long-side conductor and the fourth long-side conductor. And a second end. The first stub is connected to the first long-side conductor in the vicinity of the first end of the first feed line. The second stub is connected to the third long-side conductor in the vicinity of the first end of the third feed line.

Preferably, the resonance wavelength required for the first loop antenna element is substantially the same as the resonance wavelength required for the second loop antenna element .

  According to the present invention, a vertical antenna having a wide usable frequency band can be realized.

1 is a perspective view of an antenna according to an embodiment of the present invention. It is the figure which looked at the antenna 100 shown in FIG. 1 from the A3 direction of FIG. It is the figure which looked at the antenna 100 shown in FIG. 1 from the A4 direction of FIG. It is the figure which looked at the antenna 100 shown in FIG. 1 from the A1 direction of FIG. It is the figure which looked at the antenna 100 shown in FIG. 1 from the A2 direction of FIG. It is a schematic diagram which shows the structure of the combiner | synthesizer 21 which concerns on this Embodiment. It is a figure which shows the horizontal surface directivity of the comparative example of the antenna which concerns on this Embodiment. It is a figure which shows the horizontal surface directivity of the antenna which concerns on this Embodiment. It is the perspective view which showed the 1st modification of the antenna which concerns on this Embodiment. It is the perspective view which showed the 2nd modification of the antenna which concerns on this Embodiment. It is the perspective view which showed the 3rd modification of the antenna which concerns on this Embodiment.

  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.

  Further, the antenna according to the embodiment of the present invention can be applied to both a reception antenna and a transmission antenna.

  FIG. 1 is a perspective view of an antenna according to an embodiment of the present invention. Referring to FIG. 1, an antenna 100 includes loop antenna elements 11 and 12, feed lines LN31, LN32, LN41 and LN42, stubs 31 and 32, U baluns 35 and 36, and coaxial cables CBL1 and CBL2. Prepare.

  The loop antenna element 11 has a long-side conductor LP31, a long-side conductor LP32, a short-side conductor SP31 and a short-side conductor SP32, and circulates in a substantially rectangular shape. The loop antenna element 11 further includes a wide conductor 50 connected to both ends of the long-side conductor LP31 and both ends of the long-side conductor LP32.

  The loop antenna element 12 has a long-side conductor LP41, a long-side conductor LP42, a short-side conductor SP41 that intersects with the short-side conductor SP31, and a short-side conductor SP42 that intersects with the short-side conductor SP32. Yes. The loop antenna element 12 further includes a wide conductor 50 connected to both ends of the long-side conductor LP41 and both ends of the long-side conductor LP42.

  The respective conductors of the loop antenna element 11 and the loop antenna element 12, the stubs 31 and 32, and the feed lines LN31, LN32, LN41, and LN42 are, for example, conductor plates, that is, flat-plate conductors.

  The axis Z is the central axis of the antenna 100. The antenna 100 is supported so that the axis Z extends along the vertical direction. In this state where the antenna 100 is supported, the short-side conductors SP31 and SP41 are located on the upper side of the antenna 100, and the short-side conductors SP32 and SP42 are located on the lower side of the antenna 100. Therefore, the plane of polarization of the antenna 100 is a horizontal plane.

  The A1 direction and the A2 direction are directions along the axis Z and opposite to each other. Specifically, the A1 direction is a direction from the top to the bottom of the antenna 100, and the A2 direction is a direction from the bottom to the top of the antenna 100. Further, the A3 direction is a direction orthogonal to the axis Z. The A4 direction in FIG. 3 is a direction orthogonal to the axis Z and orthogonal to the direction A3.

  2 is a view of the antenna 100 shown in FIG. 1 as viewed from the direction A3 in FIG. 3 is a view of the antenna 100 shown in FIG. 1 as viewed from the direction A4 in FIG. 4 is a view of the antenna 100 shown in FIG. 1 as viewed from the direction A1 in FIG. FIG. 5 is a diagram of the antenna 100 shown in FIG. 1 viewed from the direction A2 in FIG.

  1 to 5, the short-side conductor SP31 and the short-side conductor SP41 are arranged so as to intersect with each other at a substantially right angle, and the short-side conductor SP32 and the short-side conductor SP42 are arranged so as to intersect with each other at a substantially right-angle. Is done.

  Hereinafter, the extending direction of the long-side conductor LP31, the long-side conductor LP32, the long-side conductor LP41, and the long-side conductor LP42, that is, the direction parallel to the Z-axis is also referred to as “vertical direction of the antenna 100”. A direction perpendicular to the Z axis (for example, the A3 direction and its reverse direction, and the A4 direction and its reverse direction) is also referred to as “the horizontal direction of the antenna 100”. In addition, the A1 direction in the installed state of the antenna 100 shown in FIG. 3 is also referred to as “vertical downward direction”, and the opposite direction, that is, the A2 direction is also referred to as “vertical upward direction”.

  Feed line LN31 has a first end connected to long-side conductor LP31, and a second end located on the opposite side of the first end and between long-side conductor LP31 and long-side conductor LP32. The first end of the feeder line LN31 is connected to the long-side conductor LP31 at a predetermined position away from the center in the extending direction of the long-side conductor LP31 (vertical direction of the antenna 100) in the extending direction, for example, vertically downward.

  The feed line LN32 has a first end connected to the long-side conductor LP32 and a second end located on the opposite side of the first end and between the long-side conductor LP31 and the long-side conductor LP32. The first end of the feeder line LN32 is connected to the long-side conductor LP32 at a predetermined position away from the center in the extending direction of the long-side conductor LP32 (vertical direction of the antenna 100) in the extending direction, for example, vertically downward.

  Feed line LN41 has a first end connected to long-side conductor LP41 and a second end located on the opposite side of the first end and between long-side conductor LP41 and long-side conductor LP42. The first end of the feeder line LN41 is connected to the long-side conductor LP41 at a predetermined position away from the center in the extending direction of the long-side conductor LP41 (vertical direction of the antenna 100) in the extending direction, for example, vertically downward.

  Feed line LN42 has a first end connected to long-side conductor LP42, and a second end located on the opposite side of the first end and between long-side conductor LP41 and long-side conductor LP42. The first end of the feeder line LN42 is connected to the long-side conductor LP42 at a position away from the center in the extending direction of the long-side conductor LP42 (vertical direction of the antenna 100) in the extending direction, for example, vertically downward.

  The long-side conductor LP31 and the long-side conductor LP32 extend along the axis Z and are arranged to face each other so as to be substantially parallel. The long-side conductor LP41 and the long-side conductor LP42 extend along the axis Z and are arranged to face each other so as to be substantially parallel. The lengths in the Z-axis direction of the long side conductors LP31, LP32, LP41, LP42 are substantially the same.

  Two wide conductors 50 are connected to each of two ends of the long side conductor LP31 (the same applies to each of the long side conductors LP32, LP41, LP42). The wide conductor may be formed integrally with the long side conductor. Due to the wide conductor 50, the width of the end of the long-side conductor (the length in the horizontal direction of the antenna 100) is in the middle portion of the long-side conductor (more specifically, the position where the feed line is connected to the long-side conductor). It becomes larger than the width of the long side conductor. That is, as shown in FIG. 2, when the width of the intermediate portion of the long-side conductor LP42 is W1 and the width (maximum value) of the end portion of the long-side conductor LP42 is W2, W1 <W2. Similarly, as shown in FIG. 3, if the width of the middle part of the long-side conductor LP31 is W3 and the width (maximum value) of the end of the long-side conductor LP31 is W4, W3 <W4.

  The shape of the wide conductor 50 is a trapezoid. Wide conductor so that the longer one of the two parallel sides of the trapezoid is longer than the shorter side from the middle part of the long conductor (the position of the long conductor to which the feed line is connected) 50 is formed.

  The short-side conductor SP31 connects one end of the long-side conductor LP31 and one end of the long-side conductor LP32 facing the one end. The short-side conductor SP32 connects the other end of the long-side conductor LP31 and the other end of the long-side conductor LP32 facing the other end. The short-side conductor SP41 connects one end of the long-side conductor LP41 and one end of the long-side conductor LP42 facing the one end. The short-side conductor SP42 connects the other end of the long-side conductor LP41 and the other end of the long-side conductor LP42 facing the other end.

  The short-side conductors SP31 and SP32 are arranged so as to extend in the A4 direction. On the other hand, the short-side conductors SP41 and SP42 are arranged to extend in the A3 direction. The length in the A4 direction of each of the short side conductors SP31 and SP32 and the length in the A3 direction of each of the short side conductors SP41 and SP42 are substantially the same.

  The short-side conductor SP31 and the short-side conductor SP32 are bent in a direction that reduces the volume of the space surrounded by the loop antenna element 11. The short-side conductor SP41 and the short-side conductor SP42 are bent in a direction that reduces the volume of the space surrounded by the loop antenna element 12. In other words, each of the short-side conductor SP31 and the short-side conductor SP32 has a recessed portion that is recessed in the direction of the space surrounded by the loop antenna element 11. Each of the short-side conductor SP41 and the short-side conductor SP42 has a recessed portion that is recessed in the direction of the space surrounded by the loop antenna element 12.

  The short-side conductors SP31 and SP41 are fixed by screws 41 at positions corresponding to both cross points. The position of the screw 41 is substantially the center of the short-side conductors SP31 and SP41. The short-side conductors SP32 and SP42 are arranged so as to cross three-dimensionally. The short-side conductors SP32 and SP42 are fixed by screws 42 at positions corresponding to both cross points. The position of the screw 42 is substantially the center of the short-side conductors SP32 and SP42.

  In the present embodiment, the short-side conductors SP31 and SP41 are fixed in contact with each other, and the short-side conductors SP32 and SP42 are fixed in contact with each other. However, an insulator may be interposed between the short-side conductors SP31 and SP41 and between the short-side conductors SP32 and SP42.

  The feed lines LN31 and LN32 are connected to the long-side conductor LP31 and the long-side conductor LP32, respectively, at the same height from the lower end of the short-side conductor SP32, for example. The feed lines LN41 and LN42 are connected to the long-side conductor LP41 and the long-side conductor LP42, for example, at substantially the same height from the lower end of the short-side conductor SP32 and at a position lower than the feed-lines LN31 and LN32.

  The feed lines LN31, LN32, LN41, and LN42 extend in the horizontal direction of the antenna 100, that is, in a direction substantially perpendicular to the long side conductors LP31, LP32, LP41, and LP42. The feed line LN31 extends in the direction from the long side conductor LP31 to the long side conductor LP32, the feed line LN32 extends in the direction from the long side conductor LP32 to the long side conductor LP31, and the feed line LN41 extends from the long side conductor LP41. The feed line LN42 extends in the direction from the long-side conductor LP42 to the long-side conductor LP41.

  Further, the second ends of the feed lines LN31, LN32, LN41, and LN42 are near the center between the long-side conductor LP31 and the long-side conductor LP32 and the long-side conductor LP41 so that the second ends of the other feed lines do not contact each other. And near the center between the long side conductors LP42.

  Here, the resonance wavelength required for the loop antenna elements 11 and 12 (the wavelength of the radio wave to be transmitted or received by the loop antenna elements 11 and 12) is both λ. The loop antenna elements 11 and 12 are antennas called “Hentena”. Accordingly, the long-side conductor LP31, the long-side conductor LP32, the long-side conductor LP41, and the long-side conductor LP42 have a length of approximately λ / 2 in the Z-axis direction. That is, the lengths L1 and L3 shown in FIGS. 2 and 3 are approximately λ / 2. Furthermore, the short-side conductor SP31 and the short-side conductor SP32 have a length of approximately λ / 6 in the A4 direction. The short-side conductor SP41 and the short-side conductor SP42 have a length of approximately λ / 6 in the A3 direction.

  The stubs 31 and 32 are provided on the loop antenna elements 11 and 12, respectively, in order to adjust the impedance of the antenna 100. The stub 31 is located between the first end connected to the long-side conductor LP31 of the loop antenna element 11 in the vicinity of the feed line LN31, and on the opposite side of the first end and between the long-side conductor LP31 and the long-side conductor LP32. And a second end. The stub 32 is located between the first end connected to the long-side conductor LP41 of the loop antenna element 12 in the vicinity of the feed line LN41, and on the opposite side of the first end and between the long-side conductor LP41 and the long-side conductor LP42. And a second end. In the present embodiment, the stub 31 is disposed on the lower side with respect to the feed line LN31, while the stub 32 is disposed on the upper side with respect to the feed line LN41.

  The U baluns 35 and 36 are formed by bending one coaxial cable having a length of approximately λ / 2 into a U shape and connecting both ends of the outer conductor of the coaxial cable. The U balun 35 is connected between the second end of the feed line LN31 and the second end of the feed line LN32. The U balun 36 is connected between the second end of the feed line LN41 and the second end of the feed line LN42. The U baluns 35 and 36 are provided in the antenna 100 in order to mutually convert balanced feeding by the antenna 100 (loop antenna elements 11 and 12) and unbalanced feeding by the coaxial cables CBL1 and CBL2.

  The coaxial cable CBL1 has an inner conductor CI1 connected to the feeding point FD1 at the second end of the feeding line LN31 and an outer conductor CO1 connected to the outer conductor of the U balun 35.

  The coaxial cable CBL2 has an inner conductor CI2 connected to the feeding point FD3 at the second end of the feeding line LN41 and an outer conductor CO2 connected to the outer conductor of the U balun 36. The electrical lengths of the coaxial cables CBL1 and CBL2 are adjusted to be different from each other by λ / 4.

  When antenna 100 is used as a receiving antenna, a synthesizer for synthesizing electrical signals (signals from loop antenna elements) transmitted through coaxial cable CBL1 and coaxial cable CBL2 is connected to coaxial cable CBL1 and coaxial cable CBL2. . On the other hand, when the antenna 100 is used as a transmission antenna, a distributor is connected to the coaxial cable CBL1 and the coaxial cable CBL2. Note that the configuration of the distributor may be the same as that of the combiner. Therefore, hereinafter, “synthesizer” and “distributor” are collectively referred to as “synthesizer”. It should be noted that the signal input / output directions of the combiner and distributor are opposite to each other.

  The synthesizer is formed by a printed circuit board, for example. FIG. 6 is a schematic diagram showing the configuration of the synthesizer 21 according to the present embodiment. Referring to FIG. 6, lines 71 to 74 connected to each other are formed on one main surface of the printed board by a metal thin film (for example, copper foil). The other main surface (hereinafter referred to as “back surface”) of the printed circuit board is almost entirely an earth pattern.

  The synthesizer 21 is a Wilkinson synthesizer in order to avoid interference between the two inputs. More specifically, the line 71 is connected to the inner conductor CI1 of the coaxial cable CBL1. The line 71 is provided with a stub ST1 for improving the VSWR (Voltage Standing Wave Ratio) characteristic. Furthermore, one end of a coil CL1 is connected to the line 71. The other end of the coil CL1 is connected to the ground pattern on the back surface of the printed circuit board through the through hole 81. The distance between one end of the coil CL1 and the other end of the coil CL1 is approximately λ / 4.

  An internal conductor CI2 of the coaxial cable CBL2 is connected to the line 72. The line 72 is provided with a stub ST2 for improving the VSWR characteristic. Furthermore, one end of a coil CL2 is connected to the line 72. The other end of the coil CL2 is connected to the ground pattern on the back surface of the printed circuit board through the through hole 82. The distance between one end of the coil CL2 and the other end of the coil CL2 is approximately λ / 4.

  Resistance element R is connected to lines 71 and 72. Lines 71 and 72 are connected to line 74. The line 74 is provided with stubs ST3 and ST4 in order to improve the VSWR characteristics.

  The line 74 is connected to the line 73. An internal conductor CI3 of the coaxial cable CBL3 is connected to the line 73. The line 73 is provided with a stub ST5 in order to improve the VSWR characteristic. Furthermore, one end of a coil CL3 is connected to the line 73. The other end of the coil CL3 is connected to the ground pattern on the back surface of the printed circuit board through the through hole 83. The distance between one end of the coil CL3 and the other end of the coil CL3 is approximately λ / 4.

  By setting the distance between one end and the other end of each of the coils CL <b> 1 to CL <b> 3 to a length of approximately λ / 4, reflected waves can be reduced and matching can be improved.

  The combiner 21 and the coaxial cables CBL1 and CBL2 are for feeding power with the phase shifted by λ / 4 between the loop antenna elements 11 and 12. The U baluns 35 and 36 and the feed lines LN31, LN32, LN41, and LN42 correspond to the “feed unit” of the present invention. In this specification, “power feeding” includes not only supplying high-frequency power to an antenna in order to transmit radio waves from the antenna, but also receiving the radio waves by the antenna.

  According to the present embodiment, two loop antenna elements (hentennas) are arranged so as to be orthogonal to each other. Further, the synthesizer 21 and the coaxial cables CBL1 and CBL2 feed power to the two loop antenna elements so that the phases are different from each other by λ / 4. Thereby, the antenna 100 functions as a horizontally polarized omnidirectional antenna. Further, the length of the antenna 100 in the vertical direction (approximately λ / 2) is larger than the length of the antenna 100 in the horizontal direction (approximately λ / 6). Therefore, according to this embodiment, a vertical horizontal polarization omnidirectional antenna can be realized.

  Furthermore, according to the present embodiment, the widths of both ends of the long-side conductor included in the two loop antenna elements (hentennas) are larger than the width of the intermediate portion of the long-side conductor. Thereby, the band of the antenna 100 can be widened.

  Furthermore, according to the present embodiment, a stub is provided on one of the two long-side conductors of the loop antenna element. Thereby, it becomes possible to adjust the impedance of the loop antenna element (hentenna) according to the impedance of the coaxial cable. By adjusting the impedance of the loop antenna element, a signal (high frequency power) can be efficiently transmitted between the loop antenna element and the coaxial cable. The number and arrangement of stubs are not particularly limited. For example, stubs may be provided on both of the two long-side conductors of the loop antenna element, or stubs may be provided at a plurality of locations on one long-side conductor.

  Furthermore, according to the present embodiment, the U balun is connected to the two feed lines of the loop antenna element. With the U balun, balanced feeding by the loop antenna element and unbalanced feeding by the coaxial cable can be mutually converted. Thereby, impedance matching between the loop antenna element and the coaxial cable can be realized.

  Next, the performance of the antenna configured as described above will be specifically described. The performance of the antenna device described below is obtained by configuring the antenna 100 so that radio waves in the frequency band (470 to 770 MHz) of UHF television broadcasting in Japan can be transmitted and received. Specifically, the antenna 100 is an antenna device suitable for transmission / reception of radio waves in the UHF band, particularly the L band (470 MHz to 584 MHz) of the terrestrial digital broadcasting frequency band (470 to 710 MHz) in Japan. The parameters of length, width and distance of each part in 100 (loop antenna elements 11 and 12) were designed.

  Hereinafter, a directivity pattern is shown as the performance of the antenna 100. Since the antenna according to the present embodiment is a horizontally polarized omnidirectional antenna, the directivity pattern is preferably as close to a circle as possible. In the present embodiment, “omnidirectional” means that the directivity deviation in the horizontal plane directivity pattern (the maximum value of the gain difference in any two directions on the horizontal plane) is 2.5 dB or less. And

  FIG. 7 is a diagram showing the horizontal plane directivity of the comparative example of the antenna according to the present embodiment. The antenna according to the comparative example is different from the antenna according to the present embodiment in that it does not include a wide conductor (indicated as “element” in FIGS. 7 and 8), but the configuration of other parts is related to the present embodiment. The configuration is the same as the corresponding portion of the antenna.

  Referring to FIG. 7, horizontal plane directivity patterns of 470 MHz, 500 MHz, 530 MHz, 560 MHz and 590 MHz are typically shown to cover the frequency band at 470 to 584 MHz. As shown in FIG. 7, the directivity deviation is larger than 2.5 dB at 470 MHz and 590 MHz.

  FIG. 8 is a diagram illustrating the horizontal plane directivity of the antenna according to the present embodiment. Referring to FIG. 8, the directivity deviation is 2.5 dB or less at each frequency of 470 MHz and 590 MHz. Furthermore, the directivity deviation is 2.5 dB or less at each frequency of 500 MHz, 530 MHz, and 560 MHz. That is, it can be understood from FIGS. 7 and 8 that the frequency band in which horizontal polarization omnidirectionality can be obtained can be expanded by connecting the wide conductor to both ends of the long-side conductor.

  Note that the configuration of the antenna according to this embodiment is not limited to the above-described configuration. Hereinafter, modifications of the antenna according to the present embodiment will be described 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. 9 is a perspective view showing a first modification of the antenna according to the present embodiment. Referring to FIG. 9 and FIG. 1, an antenna 101 according to the first modification in that the short side conductor SP31, SP32, SP41, SP 42 is a straight conductive plates, different from the antenna 100. As shown in FIG. 9, the short-side conductor of the loop antenna element may not be bent.

  FIG. 10 is a perspective view showing a second modification of the antenna according to the present embodiment. Referring to FIGS. 10 and 1, antenna 102 according to the second modification is different from antenna 100 in that wide conductor 51 is provided instead of wide conductor 50. The shape of the wide conductor 51 is a rectangle. As shown in FIG. 10, if the width of both ends of the long-side conductor is made larger than the width of the middle portion of the long-side conductor (portion to which the feed line is connected), the shape of the wide conductor 50 is particularly It is not limited. Therefore, the shape of the wide conductor 50 may be, for example, a triangle.

  FIG. 11 is a perspective view showing a third modification of the antenna according to the present embodiment. Referring to FIG. 11, antenna 103 according to the third modification includes loop antenna elements 11 and 12. In each of the antennas 100 to 102, the resonance wavelengths of the loop antenna elements 11 and 12 are substantially the same. On the other hand, in the antenna 103, the resonance wavelengths of the loop antenna elements 11 and 12 are different. Therefore, the sizes of the loop antenna elements 11 and 12 are different from each other.

Specifically, the length L1 of the long side conductor LP 31, LP32 is about 1/2 of the first wavelength lambda, the short side conductor SP31, approximately length L2 of the first wavelength lambda of SP 32 1 / 6. On the other hand, the length L3 of the long side conductor LP41 and LP42 are about 1/2 of the second wavelength λ '(λ ≠ λ') , the length L4 of the shorter side conductor SP41, SP 42 and the second wavelength lambda It is approximately 1/6 of '. In the configuration shown in FIG. 11, λ <λ ′, but λ> λ ′ may be used.

  The feed lines LN31 and LN41 are connected by a line 61. The feed lines LN32 and LN42 are connected by a line 62. For example, the inner conductor of the coaxial cable is connected to one of the lines 61 and 62 (for example, the center of the line 61), while the outer conductor of the coaxial cable is connected to the other of the lines 61 and 62 (for example, the center of the line 62). . A U balun is connected to the lines 61 and 62. That is, the lines 61 and 62 constitute a power feeding unit for feeding power to the loop antenna elements 11 and 12.

  Further, wide conductors 51 are connected to both ends of the long side conductors (LP31, LP32, LP41, LP42). As described above, the shape of the wide conductor is not particularly limited.

  Further, the stubs 33 and 34 are connected to the long side conductors LP31 and LP41, respectively. Specifically, the stub 33 is connected to the long-side conductor LP31 in the vicinity of the feed line LN31, and the stub 34 is connected to the long-side conductor LP41 in the vicinity of the feed line LN41.

  As shown in FIG. 11, wide conductors are connected to both ends of the long-side conductors of the two loop antenna elements (hentennas). Therefore, the band of each loop antenna element can be expanded. Furthermore, by combining two loop antenna elements having different sizes (that is, having different resonance wavelengths), it is possible to further widen the band of the antenna. Therefore, it is possible to widen the use frequency band also in this modification.

  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.

11, 12 loop antenna element, 21 combiner, 31-34, ST1-ST5 stub, 35, 36 U balun, 41, 42 screw, 50, 51 wide conductor, 61, 62, 71-74 line, 81-83 through Hall, 100 to 103 antenna, CBL1 to CBL3 coaxial cable, CI1 to CI3 inner conductor, CL1 to CL3 coil, CO1, CO2 outer conductor, FD1 to FD4 feeding point, LN31, LN32, LN41, LN42 feeding line, LP31, LP32, LP41, LP 42 long side conductor, R the resistance element, SP31, SP32, SP41, SP 42 short side conductor, Z-axis.

Claims (2)

The first and second long-side conductors arranged so as to face each other, and a first connecting the one end of the first long-side conductor and the one end of the second long-side conductor facing each other A first loop antenna element having a short side conductor and a second short side conductor connecting the other end of the first long side conductor and the other end of the second long side conductor facing each other;
Third and fourth long-side conductors arranged so as to face each other, and a third connecting the one end of the third long-side conductor and the one end of the fourth long-side conductor facing each other A second loop antenna element having a short-side conductor, and a fourth short-side conductor connecting the other end of the third long-side conductor and the other end of the fourth long-side conductor facing each other;
A power feeding unit for feeding power to the first and second loop antenna elements,
The length of each of the first and second long-side conductors in the extending direction is approximately ½ of the resonance wavelength required for the first loop antenna element,
The length in the extending direction of each of the first and second short-side conductors is approximately 1/6 of the resonance wavelength required for the first loop antenna element,
The length in the extending direction of each of the third and fourth long-side conductors is approximately ½ of the resonance wavelength required for the second loop antenna element,
The length in the extending direction of each of the third and fourth short-side conductors is approximately 1/6 of the resonance wavelength required for the second loop antenna element,
The width of the two ends of each of the fourth long side conductor from the first is much larger than the width of the intermediate portion located between said two ends,
In the first and second loop antenna elements, the first short-side conductor and the third short-side conductor intersect each other at substantially right angles, and the second short-side conductor and the fourth short-side conductor The side conductors are arranged so as to cross each other at a substantially right angle,
A first end connected to the intermediate portion of the first long-side conductor, and a second end located on the opposite side of the first end and between the first long-side conductor and the second long-side conductor. A first feed line having an end;
A first end connected to the intermediate portion of the second long-side conductor and a second end located on the opposite side of the first end and between the first long-side conductor and the second long-side conductor. A second feed line having ends;
A first end connected to the intermediate portion of the third long-side conductor and a second end located on the opposite side of the first end and between the third long-side conductor and the fourth long-side conductor. A third feed line having ends;
A first end connected to the intermediate portion of the fourth long-side conductor, and a second end located on the opposite side of the first end and between the third long-side conductor and the fourth long-side conductor. A fourth feed line having ends;
A first stub connected to the first long-side conductor in the vicinity of the first end of the first feed line;
An antenna further comprising: a second stub connected to the third long-side conductor in the vicinity of the first end of the third feed line . The resonance wavelength is required for the first loop antenna element, wherein the Ru substantially equal der the resonance wavelength required for the second loop antenna element, the antenna according to claim 1.

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