JP4858971B2 - Broadband loop antenna - Google Patents

Description

  The present invention relates to a broadband loop antenna having a wide band using one single wavelength loop antenna. In addition, the present invention relates to a broadband loop antenna in which a one-wavelength loop antenna can be configured with a narrow dimension.

Japanese Laid-Open Patent Application No. 03-108903 discloses a technique of a loop antenna for the purpose of widening the band used as a window glass antenna for automobiles. The technique disclosed in this publication is a double arrangement of two loop antennas along the periphery of the window glass surface of an automobile. For example, the outer loop antenna is set to resonate with radio waves in a low frequency band of the FM broadcast band, and the inner loop antenna is set to resonate with radio waves in a high frequency band of the FM broadcast band. By using two loop antennas having different resonance frequencies, the bandwidth is increased.
Japanese Patent Laid-Open No. 03-108903

  Since the technique described in Patent Document 1 described above is disposed on the peripheral portion of the window glass of an automobile, its outer shape is considerably large, and attachment work or the like is not easy. Further, in the technique described in Patent Document 1, it must be disposed at the peripheral portion of a portion where a defogger line such as a rear window glass of an automobile is not disposed, and the shape and size of the rear window glass differ depending on the vehicle type. Accordingly, the shape and size of the antenna must be set appropriately. In addition, the size of the antenna differs depending on the shape and size of the rear window glass, and it is not always possible to set the outer loop antenna and the inner loop antenna that are disposed twice so as to resonate with radio waves in a desired frequency band. Absent.

  The present invention has been made in view of the technical circumstances described in Patent Document 1, and an object of the present invention is to provide a wideband loop antenna having a wide band using one single-wavelength loop antenna. It is another object of the present invention to provide a broadband loop antenna that can be configured with a dimension that is narrow enough to be disposed between defogger lines.

  In order to achieve such an object, the wideband loop antenna of the present invention forms a one-wavelength loop antenna so that the antenna elements are line-symmetric, and two feeding points at the line-symmetrical positions of the one-wavelength loop antenna are provided. One end of each of the two broadband elements is connected, and inside the one-wavelength loop antenna, at a position that is two line symmetrical in the vicinity of an electrical length of ¼ wavelength from the feeding point of the antenna element, The other ends of the two broadbanding elements are connected to each other, and the two broadbanding elements are provided so as to be line-symmetric.

  Further, a one-wavelength loop antenna is formed so that the antenna elements are line-symmetric, and one end of each of the two broadband elements is connected to two feeding points at the line-symmetrical position of the one-wavelength loop antenna. Inside the wavelength loop antenna, the other ends of the two broadbanding elements are respectively brought close to two line-symmetrical positions in the vicinity of an electrical length of ¼ wavelength from the feeding point of the antenna element. It is also possible to arrange the two broadbanding elements so as to be line-symmetric.

  Then, the two broadening elements are formed by a portion parallel to the line-symmetric symmetry axis and a portion that is bent 90 degrees and is in a direction perpendicular to the symmetry axis. A parasitic element may be disposed in parallel with the portion in the direction orthogonal to the axis, and the parasitic element may be set to a quarter wavelength of a desired frequency.

  Further, the one-wavelength loop antenna may be formed in a diamond shape, and the outer dimension in the direction of the symmetry axis may be formed to be 1/20 wavelength of the one-wavelength loop antenna.

  The wideband loop antenna according to claim 1, wherein the 1-wavelength loop antenna formed so that the antenna elements are line-symmetrical has a feed point that is a current maximum point and a feed point that is a voltage maximum point. By connecting both ends of the broadband element to the position of the electrical length of 4 wavelengths and forming the broadband element in line symmetry, the broadband element has a phase different from the current flowing through the antenna element of the one-wavelength loop antenna. An electric current flows, and an electric field is generated by generating a potential difference. This electric field is considered to act equivalent to a parallel capacitance. Further, a current is also distributed in the broadband element itself, and this current distribution is considered to act equivalent to a series inductance. Therefore, it is considered that the broadband is achieved by the parallel capacitance and the series inductance.

  In the wideband loop antenna according to claim 2, since one end of the wideband element is arranged close to the position of the electrical length of ¼ wavelength from the feeding point which is the maximum voltage point, The circuit is equivalent to one end connected to the position of the electrical length of ¼ wavelength from the feeding point through the capacitance in series, and the bandwidth is increased in the same manner as in the configuration of claim 1. it is conceivable that.

  In the broadband loop antenna according to claim 3, a parasitic element is disposed in parallel to a portion in a direction perpendicular to the symmetry axis of the broadband element, and the parasitic element is line-symmetric and has a desired shape. Since the wavelength is set to 1/4 of the frequency, in addition to the broadening of the bandwidth according to the configuration of claim 1, the parasitic element resonates at the desired frequency, thereby improving the characteristics near the desired frequency and further widening the bandwidth. Is made.

  Furthermore, in the broadband loop antenna according to claim 10, the one-wavelength loop antenna is formed in a rhombus, and the outer dimension in the direction of the symmetry axis is formed to 1/20 wavelength of the one-wavelength loop antenna. For example, when designed as an antenna for terrestrial digital television using a band of 470 MHz to 770 MHz, the overall dimension in the direction of the symmetry axis can be shortened to 25 cm or less to shorten the width of the entire antenna. It can arrange | position without straddling a defogger line between 30 cm which is the general space | interval of the defogger line arrange | positioned at a rear window glass.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram of a first embodiment of a broadband loop antenna according to the present invention. FIG. 2 is a VSWR characteristic diagram of the broadband loop antenna of FIG. FIG. 3 is a Smith chart of the broadband loop antenna of FIG. FIG. 4 is a diagram showing a modification of the first embodiment of the broadband loop antenna according to the present invention. FIG. 5 is a VSWR characteristic diagram of a modification of the first embodiment of the broadband loop antenna of FIG. FIG. 6 is a Smith chart of a modification of the first embodiment of the broadband loop antenna of FIG. FIG. 7 is a diagram of a conventional one-wavelength loop antenna having the same shape as the first embodiment. FIG. 8 is a VSWR characteristic diagram of the conventional one-wavelength loop antenna of FIG. FIG. 9 is a Smith chart of the conventional one-wavelength loop antenna of FIG.

  First, the structure of the first embodiment of the broadband loop antenna of the present invention will be described with reference to FIG. In FIG. 1, the one-wavelength loop antenna 10 is formed in a rhombus whose antenna elements are line symmetric with respect to a vertical axis of symmetry and a horizontal axis of symmetry orthogonal to the vertical axis. The two feeding points 12, 12 are arranged at positions that are line-symmetric with respect to the symmetry axis in the vertical direction. In this one-wavelength loop antenna 10, all four sides have an electrical length of ¼ wavelength, the vertical dimension is ¼ wavelength, and feeding points 12 and 12 are current maximum points. The corners 14 and 14 at the left and right line symmetrical positions having an electrical length of ¼ wavelength from the points 12 and 12 are the maximum voltage points. Then, both ends of the broadbanding elements 16 and 16 are connected to the feeding points 12 and 12 and the corners 14 and 14 inside the one-wavelength loop antenna 10, respectively. In addition, these broadbanding elements 16, 16 are composed of portions 16a, 16a parallel to the vertical symmetry axis and left and right portions 16b, 16b perpendicular to the vertical symmetry axis, which are bent by 90 °. Thus, the two broadband elements 16, 16 are arranged so as to be line symmetric with respect to the symmetry axis in the vertical direction. The interval between the portions 16a and 16a parallel to the vertical axis of symmetry of the broadband elements 16 and 16 is set to 1/20 wavelength or less. As an example, the wideband loop antenna of the present invention is set to have one wavelength with respect to 620 MHz, and when its VSWR characteristic is measured, as shown in FIG. 2, the VSWR is in a wide range of about 300 MHz from 530 to 830 MHz. Excellent characteristics of 2 or less were obtained. In the Smith chart, as shown in FIG. 3, an input / output impedance as low as about 50Ω is obtained at the center frequency, and matching with a receiver or the like is easy.

  Here, as in the present invention, the VSWR characteristic of the conventional single-wavelength loop antenna 10 alone shown in FIG. 7 measured at 620 MHz is VSWR of 545 to 570 MHz and 730 MHz as shown in FIG. As shown in FIG. 9, the Smith chart also has a high input / output impedance of 100 to 200Ω, which is a typical characteristic of a one-wavelength loop antenna.

  Therefore, compared with the conventional single-wavelength loop antenna 10 shown in FIG. 7, the broadband loop antenna of the present invention shown in FIG. It is clear that This is because by providing the broadbanding elements 16 and 16, a current having a phase different from the current flowing through the antenna element of the one-wavelength loop antenna 10 flows through the broadbanding elements 16 and 16, thereby generating an electric field by generating a potential difference. Due to This electric field is considered to act equivalent to a parallel capacitance. Further, it is considered that the current distributed in the broadband elements 16 and 16 itself acts equivalent to the series inductance. Therefore, in the first embodiment of the wideband loop antenna of the present invention, the bandwidth can be increased as if the parallel capacitance and the series inductance were appropriately connected to the one-wavelength loop antenna 10, and A low input / output impedance is obtained.

Furthermore, the inventors made a modification of the first embodiment as shown in FIG. 4 and measured its characteristics. In the modification shown in FIG. 4, one end of the broadband elements 16, 16 is connected to the feeding points 12, 12 of the one-wavelength loop antenna 10, and the other end is connected to the corners 14, 14 that are the maximum voltage points. They are arranged close to each other. As shown in FIG. 5, the VSWR characteristic is a VSWR of 2 or less in a wide range of 545 to 660 MHz, and the Smith chart shows a low input / output impedance although it does not become about 50Ω as shown in FIG. It was. In the modification shown in FIG. 4, it is considered that an equivalent circuit is formed when the other ends of the broadband elements 16 and 16 are connected to the corners 14 and 14 of the maximum voltage point via a capacitance in series. It is done.

  As described in the above embodiment, the broadband elements 16 and 16 include portions 16a and 16a that are parallel to the vertical axis of symmetry, and portions 16b and 16b that are bent 90 ° and orthogonal to the vertical axis of symmetry. It has been confirmed by experiments of the inventors that it may be formed of a curved line as long as it is arranged so as to be line symmetric with respect to the vertical axis of symmetry. Further, the other end of the broadband elements 16, 16 is not limited to the one connected to or close to the corners 14, 14 of the maximum voltage point as in the above embodiment, It has been confirmed that it may be connected in the vicinity of 14 or close to it. Further, in the modification shown in FIG. 4, one end of the broadbanding elements 16, 16 is connected to the feeding points 12, 12, and the other end is not connected to the corners 14, 14 but is disposed in proximity. However, the present invention is not limited to this, and one end of the broadband elements 16, 16 may be disposed close to the feeding points 12, 12 and the other end may be connected to the corners 14, 14. Then, both ends of the broadband elements 16 and 16 are connected to the feeding points 12 and 12 and the corners 14 and 14, respectively, and the middle of the broadband elements 16 and 16 is cut so that the cut ends face each other. May be arranged close to each other.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a diagram of a second embodiment of the broadband loop antenna of the present invention. FIG. 11 is a VSWR characteristic diagram of the broadband loop antenna of FIG. FIG. 12 is a Smith chart of the broadband loop antenna of FIG. FIG. 13 is a diagram showing a modified example in which the parasitic element is omitted from the second embodiment of the broadband loop antenna according to the present invention. FIG. 14 is a VSWR characteristic diagram of a modification of the second embodiment of the wideband loop antenna of FIG. FIG. 15 is a Smith chart of a modification of the second embodiment of the broadband loop antenna of FIG. FIG. 16 is a diagram of a conventional one-wavelength loop antenna having the same shape as that of the second embodiment. FIG. 17 is a VSWR characteristic diagram of the conventional one-wavelength loop antenna of FIG. FIG. 18 is a Smith chart of the conventional one-wavelength loop antenna of FIG. FIG. 19 is a diagram showing an example in which the second embodiment of the broadband loop antenna of the present invention is arranged on a window glass of an automobile. FIG. 20 is a diagram showing that the second embodiment of the broadband loop antenna according to the present invention can be disposed between the defogger lines. 10 to 20, the same or equivalent members as those in FIGS. 1 to 9 are denoted by the same reference numerals and redundant description is omitted.

  The structure of the second embodiment of the broadband loop antenna of the present invention shown in FIG. 10 is different from the first embodiment shown in FIG. The parasitic element 18 is line-symmetrical with respect to the vertical axis of symmetry, and is formed so as to be extremely narrow, and parallel to the portions 16b and 16b in the direction perpendicular to the vertical axis of symmetry of the broadband elements 16 and 16. It arrange | positions so that it may become. The length of the parasitic element 18 is set equal to the length of a quarter wavelength of a frequency higher than the resonance frequency of the one-wavelength loop antenna 10. As an example, the second embodiment of the broadband loop antenna of the present invention is set to have one wavelength with respect to 620 MHz, and the parasitic element 18 is also set to a quarter wavelength of 620 MHz. When the VSWR characteristics of the broadband loop antenna having such a configuration were measured, as shown in FIG. 11, excellent characteristics with a VSWR of 2.5 or less were obtained in a wide range of 430 to 700 MHz. Also, in the Smith chart, as shown in FIG. 12, a low input / output impedance close to about 50Ω is obtained, and matching with a receiver or the like is easy.

  Furthermore, the inventors made a modification of the second embodiment as shown in FIG. 13 and measured its characteristics. In the modification shown in FIG. 13, the parasitic element 18 is omitted. In such a modified example, the VSWR characteristic is worse than that shown in FIG. 11 as shown in FIG. 14, and the Smith chart is compared with that shown in FIG. 12 as shown in FIG. Therefore, the input / output impedance is a little high. Therefore, it was confirmed that the parasitic element 18 greatly contributed to the improvement of the characteristics.

  Here, as shown in FIG. 16, when the conventional single-wavelength loop antenna 10 alone is set in the same manner as the second embodiment of the present invention and the VSWR characteristics are measured, as shown in FIG. As shown in FIG. 18, the Smith chart has a higher input / output impedance, which is a characteristic of the one-wavelength loop antenna, as shown in FIG. Yes.

  Therefore, the second embodiment of the broadband loop antenna of the present invention shown in FIG. 10 has a very narrow shape but has a wider bandwidth than the conventional single-wavelength loop antenna 10 shown in FIG. It is obvious that the matching is easy because the input / output impedance is low. This is achieved by providing the broadbanding elements 16, 16 and the parasitic element 18.

  As described above, in the second embodiment of the wideband loop antenna of the present invention shown in FIG. 10, high antenna performance is obtained with a very narrow shape. Therefore, as shown in FIG. It can be placed anywhere without obstructing visibility. In FIG. 19, “a” is disposed on the upper portion of the front window glass, “b” is disposed on the upper portion of the rear window glass, and “c” is disposed on the upper portion of the side window glass.

  Furthermore, in the second embodiment of the wideband loop antenna of the present invention shown in FIG. 10, for example, when designed as a terrestrial digital television antenna using a band of 470 MHz to 770 MHz, the vertical dimension is 1. / 20 wavelength, including a wavelength shortening effect due to the action of glass as a dielectric, can be formed to about 25 cm. Therefore, as shown in FIG. 20, the defogger lines 20, 20... Can be arranged between the defogger lines 20, 20.

  Furthermore, a third embodiment of the present invention will be described with reference to FIGS. FIG. 21 is a diagram of a third embodiment of the broadband loop antenna according to the present invention. FIG. 22 is a VSWR characteristic diagram of the broadband loop antenna of FIG. FIG. 23 is a Smith chart of the broadband loop antenna of FIG. FIG. 24 is a diagram showing a modification in which the parasitic element is omitted from the third embodiment of the broadband loop antenna according to the present invention. FIG. 25 is a VSWR characteristic diagram of a modification of the second embodiment of the wideband loop antenna of FIG. FIG. 26 is a Smith chart of a variation of the second embodiment of the broadband loop antenna of FIG. FIG. 27 is a diagram of a conventional one-wavelength loop antenna having the same shape as that of the third embodiment. FIG. 28 is a VSWR characteristic diagram of the conventional one-wavelength loop antenna of FIG. FIG. 29 is a Smith chart of the conventional one-wavelength loop antenna of FIG. 21 to 29, the same or equivalent members as those in FIGS. 1 to 20 are denoted by the same reference numerals, and redundant description will be omitted.

  The structure of the third embodiment of the broadband loop antenna of the present invention shown in FIG. 21 is different from the first embodiment shown in FIG. 1 in that the one-wavelength loop antenna 10 is formed in a rectangular shape. The vertical dimension is set to 1/8 wavelength of the resonance frequency. Then, both ends of the broadband elements 16, 16 are connected to the feeding points 12, 12 and the intermediate points 22, 22 located at a quarter wavelength from the feeding point, inside the one-wavelength loop antenna 10. Moreover, one parasitic element 18 is arranged so as to be line-symmetric with respect to the vertical symmetry axis in parallel to the portions 16b, 16b in the direction perpendicular to the vertical symmetry axis of the broadband elements 16, 16. The The parasitic element 18 is set to a quarter wavelength that is higher than the resonance frequency of the one-wavelength loop antenna 10. As an example, the third embodiment of the broadband loop antenna of the present invention is set to have one wavelength with respect to 620 MHz, and the parasitic element 18 is set to a quarter wavelength of 770 MHz. When the VSWR characteristic of the broadband loop antenna having such a configuration was measured, as shown in FIG. 22, excellent characteristics with a VSWR of approximately 2 or less were obtained in a wide range of 300 MHz from 500 to 800 MHz. In the Smith chart, as shown in FIG. 23, a low input / output impedance close to about 50Ω is obtained at a center frequency of 620 MHz, and matching with a receiver or the like is easy.

  Furthermore, the inventors made a modification of the third embodiment as shown in FIG. 24 and measured its characteristics. In the modification shown in FIG. 24, the parasitic element 18 is omitted. In such a modification, as shown in FIG. 25, the VSWR characteristic is slightly deteriorated to VSWR of 2.5 or less at 500 to 700 MHz as compared with that shown in FIG. As shown in FIG. 26, the input / output impedance is slightly higher than that shown in FIG. Therefore, even in the third example, it was confirmed that the parasitic element 18 greatly contributed to the improvement of the characteristics.

  Here, as shown in FIG. 27, when the conventional single-wavelength loop antenna 10 is set in a rectangular shape as in the third embodiment of the present invention and the VSWR characteristics are measured, as shown in FIG. 28, FIGS. As shown in FIG. 29, the Smith chart has a higher input / output impedance that is characteristic of the one-wavelength loop antenna than those shown in FIG. 23 and FIG. Yes.

  Therefore, in the third embodiment of the wideband loop antenna of the present invention shown in FIG. 21, the bandwidth is extremely wide and the input / output impedance is significantly lower than that of the conventional single wavelength loop antenna 10 shown in FIG. It is clear that it is low and easy to align. In the third embodiment, the rectangular shape is not limited to the above embodiment. The parasitic element 18 may be set to a quarter wavelength of a desired frequency that needs to be improved.

  A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 30 is a diagram of a fourth embodiment of the wideband loop antenna according to the present invention. FIG. 31 is a VSWR characteristic diagram of the broadband loop antenna of FIG. FIG. 32 is a Smith chart of the broadband loop antenna of FIG. FIG. 33 is a diagram of a conventional one-wavelength loop antenna having the same shape as that of the fourth embodiment. FIG. 34 is a VSWR characteristic diagram of the conventional one-wavelength loop antenna of FIG. FIG. 35 is a Smith chart of the conventional one-wavelength loop antenna of FIG. 30 to 35, the same or equivalent members as in FIGS. 1 to 29 are denoted by the same reference numerals, and redundant description is omitted.

  The structure of the fourth embodiment of the wideband loop antenna of the present invention shown in FIG. 30 is different from the first embodiment shown in FIG. 1 in that the one-wavelength loop antenna 10 is formed in a regular hexagon. In addition, this regular hexagon has a corner portion in the vertical direction, and feeding points 12 and 12 are provided at the corner portion in a line-symmetrical position with respect to the symmetry axis in the vertical direction. Then, both ends of the broadband elements 16, 16 are connected to the feeding points 12, 12 and the intermediate points 22, 22 located at a quarter wavelength from the feeding point, inside the one-wavelength loop antenna 10. The fourth embodiment of the broadband loop antenna of the present invention is set to have one wavelength for 620 MHz. When the VSWR characteristic of the broadband loop antenna having such a configuration was measured, as shown in FIG. 31, a characteristic with a VSWR of approximately 3.5 or less was obtained in a wide range of 500 to 800 MHz. In the Smith chart, as shown in FIG. 32, a low input / output impedance close to 50Ω is obtained.

  Here, as shown in FIG. 33, when the conventional single-wavelength loop antenna 10 alone is set to a regular hexagon as in the fourth embodiment of the present invention and the VSWR characteristics are measured, as shown in FIG. As shown in FIG. 35, the Smith chart has a higher input / output impedance than that shown in FIG.

  Therefore, even in the fourth embodiment of the wideband loop antenna of the present invention shown in FIG. 30, the wideband elements 16 and 16 are arranged as compared with the conventional single wavelength loop antenna 10 shown in FIG. Therefore, it is clear that the bandwidth is remarkably increased and the input / output impedance is low and matching is easy. In the fourth embodiment, the shape is not limited to a regular hexagon, and may be a regular pentagon, a regular octagon, or the like.

  A fifth embodiment of the present invention will be described with reference to FIGS. FIG. 36 is a diagram of a fifth embodiment of the wideband loop antenna according to the present invention. FIG. 37 is a VSWR characteristic diagram of the broadband loop antenna of FIG. FIG. 38 is a Smith chart of the broadband loop antenna of FIG. FIG. 39 is a diagram of a conventional one-wavelength loop antenna having the same shape as that of the fifth embodiment. FIG. 40 is a VSWR characteristic diagram of the conventional one-wavelength loop antenna of FIG. FIG. 41 is a Smith chart of the conventional one-wavelength loop antenna of FIG. 36 to 41, the same or equivalent members as in FIGS. 1 to 35 are denoted by the same reference numerals, and redundant description is omitted.

  The structure of the fifth embodiment of the wideband loop antenna of the present invention shown in FIG. 36 differs from the first embodiment shown in FIG. 1 in that the one-wavelength loop antenna 10 is formed in a circular shape. The feeding points 12 and 12 are provided at positions symmetrical with respect to the vertical axis of symmetry, and the feeding points 12 and 12 and the intermediate points 22 and 22 located at an electrical length of ¼ wavelength from the feeding point are 1 Inside the wavelength loop antenna 10, both ends of the broadbanding elements 16, 16 are connected. The fifth embodiment of the broadband loop antenna of the present invention is set to have one wavelength with respect to 620 MHz. When the VSWR characteristics of the broadband loop antenna having such a configuration were measured, as shown in FIG. 37, excellent characteristics with a VSWR of approximately 3 or less were obtained in a wide range of 500 to 800 MHz. Further, in the Smith chart, as shown in FIG. 38, a low input / output impedance is obtained.

  Here, as shown in FIG. 39, when the conventional single-wavelength loop antenna 10 is set in a circle like the fifth embodiment of the present invention and the VSWR characteristics are measured, as shown in FIG. 40, the one shown in FIG. As shown in FIG. 41, the Smith chart also has a higher input / output impedance than that shown in FIG.

  Therefore, even in the fifth embodiment of the wideband loop antenna of the present invention shown in FIG. 36, the wideband elements 16 and 16 are arranged as compared with the conventional single wavelength loop antenna 10 shown in FIG. Therefore, it is clear that the bandwidth is remarkably increased and the input / output impedance is low and matching is easy. In the fifth embodiment, the shape is not limited to a circle but may be an ellipse.

  A sixth embodiment of the present invention will be described with reference to FIGS. FIG. 42 is a diagram of a sixth embodiment of the broadband loop antenna according to the present invention. 43 is a VSWR characteristic diagram of the broadband loop antenna of FIG. FIG. 44 is a Smith chart of the broadband loop antenna of FIG. 42 to 44, the same or equivalent members as in FIGS. 1 to 41 are denoted by the same reference numerals, and redundant description is omitted.

  The structure of the sixth embodiment of the wideband loop antenna of the present invention shown in FIG. 42 differs from the first embodiment shown in FIG. 1 in that the outer shape is formed as a diamond-shaped single-wavelength loop antenna and is symmetrical in the vertical direction. The sides from the feeding points 12 and 12 provided at positions symmetrical with respect to the axis to the corners 14 and 14 at the electrical length of ¼ wavelength from the feeding points 12 and 12 and the one-wavelength loop antenna 10 Inside, the wide band conductive metal plates 24 and 24 surrounded by the sides parallel to the vertical axis of symmetry from the feeding points 12 and 12 and the sides of the corners 14 and 14 on the horizontal axis of symmetry are vertically It is provided in line symmetry with respect to the symmetry axis. Further, conductive metal lines 26 are provided symmetrically along the outer shape of the rhombus from the corners 14 and 14. In other words, the triangular wideband conductive metal plates 24, 24 cover the part surrounded by the wideband elements 16, 16 and the sides connecting the feeding points 12, 12 and the corners 14, 14 of the first embodiment. It is provided. The sixth embodiment of the broadband loop antenna is also set so that the outer periphery of the diamond-shaped one-wavelength loop antenna has one wavelength with respect to 620 MHz. When the VSWR characteristic of the broadband loop antenna having such a configuration was measured, as shown in FIG. 43, excellent characteristics with a VSWR of approximately 3 or less were obtained in a wide range of 550 to 870 MHz. In the Smith chart, as shown in FIG. 44, a low input / output impedance close to about 50Ω is obtained near the center frequency.

  Therefore, as shown in FIG. 42, even if the wideband conductive plates 24, 24 are provided in place of the wideband elements 16, 16 of the first embodiment, a wide band can be achieved and a low input / output impedance can be obtained.

  Here, in the sixth embodiment of the wideband loop antenna of the present invention shown in FIG. 42, a wideband conductive metal thin film may be provided instead of the wideband conductive metal plates 24 and 24. A broadband conductive metal thin film is effective when an antenna is disposed on a film surface or the like. In addition, the area of the side connecting the feeding points 12 and 12 and the corners 14 and 14 of the first embodiment is expanded to the position where the broadbanding elements 16 and 16 are provided to form a broadbanding conductive metal part. Also good. Further, a triangular broadband conductive metal plate or a broadband conductive metal is formed so as to cover a portion surrounded by the broadband elements 16 and 16 and the side connecting the feeding points 12 and 12 and the corners 14 and 14 of the first embodiment. A thin film may be provided.

  In the above-described embodiment, the broadband elements 16 and 16 include the portions 16a and 16a in the direction parallel to the symmetry axis in the vertical direction and the portions 16b and 16b in the direction orthogonal thereto, but are not limited thereto. The feeding points 12 and 12 and the corners 14 and 14 may be connected by a curve as long as they are line symmetric with respect to the symmetry axis in the vertical direction. Furthermore, instead of the side parallel to the vertical axis of symmetry of the wideband conductive metal plates 24 and 24 and the side perpendicular to the side, the feeding point 12 can be used if the line is symmetrical with respect to the vertical axis of symmetry. , 12 and corners 14 and 14 may be formed with a side connecting with a curve.

It is a figure of 1st Example of the broadband loop antenna of this invention. It is a VSWR characteristic view of the broadband loop antenna of FIG. It is a Smith chart of the broadband loop antenna of FIG. It is a figure of the modification of 1st Example of the broadband loop antenna of this invention. FIG. 6 is a VSWR characteristic diagram of a modification of the first embodiment of the broadband loop antenna of FIG. 4. 6 is a Smith chart of a modification of the first embodiment of the broadband loop antenna of FIG. It is a figure of the conventional 1 wavelength loop antenna of the same shape as 1st Example. It is a VSWR characteristic figure of the conventional 1 wavelength loop antenna of FIG. It is a Smith chart of the conventional 1 wavelength loop antenna of FIG. It is a figure of 2nd Example of the broadband loop antenna of this invention. It is a VSWR characteristic view of the broadband loop antenna of FIG. FIG. 11 is a Smith chart of the broadband loop antenna of FIG. 10. It is a figure of the modification which excluded the parasitic element from 2nd Example of the broadband loop antenna of this invention. FIG. 14 is a VSWR characteristic diagram of a modification of the second embodiment of the broadband loop antenna of FIG. 13. It is a Smith chart of the modification of 2nd Example of the broadband loop antenna of FIG. It is a figure of the conventional 1 wavelength loop antenna of the same shape as 2nd Example. It is a VSWR characteristic figure of the conventional 1 wavelength loop antenna of FIG. 18 is a Smith chart of the conventional one-wavelength loop antenna of FIG. It is a figure which shows the example which has arrange | positioned the 2nd Example of the broadband loop antenna of this invention to the window glass of a motor vehicle. It is a figure which shows that 2nd Example of the broadband loop antenna of this invention can be arrange | positioned between defogger lines. It is a figure of 3rd Example of the broadband loop antenna of this invention. FIG. 22 is a VSWR characteristic diagram of the broadband loop antenna of FIG. 21. FIG. 22 is a Smith chart of the broadband loop antenna of FIG. 21. It is a figure of the modification which excluded the parasitic element from 3rd Example of the broadband loop antenna of this invention. FIG. 25 is a VSWR characteristic diagram of a modification of the second embodiment of the wideband loop antenna of FIG. 24. It is a Smith chart of the modification of 2nd Example of the broadband loop antenna of FIG. It is a figure of the conventional 1 wavelength loop antenna of the same shape as 3rd Example. It is a VSWR characteristic view of the conventional single wavelength loop antenna of FIG. It is a Smith chart of the conventional 1 wavelength loop antenna of FIG. It is a figure of 4th Example of the broadband loop antenna of this invention. FIG. 31 is a VSWR characteristic diagram of the broadband loop antenna of FIG. 30. FIG. 31 is a Smith chart of the broadband loop antenna of FIG. 30. FIG. It is a figure of the conventional 1 wavelength loop antenna of the same shape as 4th Example. It is a VSWR characteristic figure of the conventional 1 wavelength loop antenna of FIG. It is a Smith chart of the conventional 1 wavelength loop antenna of FIG. It is a figure of 5th Example of the broadband loop antenna of this invention. FIG. 37 is a VSWR characteristic diagram of the broadband loop antenna of FIG. 36. FIG. 37 is a Smith chart of the broadband loop antenna of FIG. 36. It is a figure of the conventional 1 wavelength loop antenna of the same shape as 5th Example. FIG. 40 is a VSWR characteristic diagram of the conventional one-wavelength loop antenna of FIG. 39. 40 is a Smith chart of the conventional one-wavelength loop antenna of FIG. It is a figure of 6th Example of the broadband loop antenna of this invention. 43 is a VSWR characteristic diagram of the broadband loop antenna of FIG. 42. FIG. 43 is a Smith chart of the wideband loop antenna of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 1 wavelength loop antenna 12 Feed point 14 Corner 16 Broadband element 18 Parasitic element 20 Defogah line 22 Midpoint 24 Broadband conductive metal plate

Claims (16)

A one-wavelength loop antenna is formed so that the antenna elements are line-symmetric, and one end of each of the two broadband elements is connected to two feeding points at the line-symmetrical position of the one-wavelength loop antenna. Inside the antenna, the other ends of the two broadband elements are respectively connected to two line-symmetrical positions in the vicinity of the electrical length of ¼ wavelength from the feeding point of the antenna element, and A wideband loop antenna characterized in that two wideband elements are provided so as to be line-symmetric. A one-wavelength loop antenna is formed so that the antenna elements are line-symmetric, and one end of each of the two broadband elements is connected to two feeding points at the line-symmetrical position of the one-wavelength loop antenna. Inside the antenna, the other two broadbanding elements are arranged close to each other at two line-symmetric positions in the vicinity of the electrical length of ¼ wavelength from the feeding point of the antenna element. In addition, the wideband loop antenna is characterized in that the two wideband elements are provided so as to be line-symmetric. 2. The wideband loop antenna according to claim 1, wherein the two wideband elements are formed by a portion parallel to the line-symmetric symmetry axis and a portion in a direction perpendicular to the symmetry axis by being bent 90 degrees. The parasitic element is arranged in parallel to the portion of the broadband element perpendicular to the axis of symmetry, and the parasitic element is line-symmetric and set to a quarter wavelength of a desired frequency. A wideband loop antenna characterized by 2. The wideband loop antenna according to claim 1, wherein the two wideband elements are formed by a portion parallel to the line-symmetric symmetry axis and a portion in a direction perpendicular to the symmetry axis by being bent 90 degrees. The wideband loop antenna is characterized in that an interval between the portions parallel to the symmetry axis of the wideband element is set to 1/20 wavelength or less of a resonance frequency of the one-wavelength loop antenna. 5. The broadband loop antenna according to claim 1, wherein the one-wavelength loop antenna is formed so as to be line symmetric with respect to a symmetry axis orthogonal to the symmetry axis in the vertical direction. A broadband loop antenna characterized by 6. The broadband loop antenna according to claim 1, wherein the one-wavelength loop antenna is formed in a diamond shape. 6. The broadband loop antenna according to claim 1, wherein the one-wavelength loop antenna is formed in a polygonal shape. 6. The broadband loop antenna according to claim 1, wherein the one-wavelength loop antenna is formed in a circular or elliptical shape. 6. The broadband loop antenna according to claim 1, wherein the one-wavelength loop antenna is formed in a rectangular shape whose dimension in the direction of the symmetry axis of the line object is shorter than the dimension in the direction perpendicular to the symmetry axis. A broadband loop antenna characterized by that. 4. The broadband loop antenna according to claim 3, wherein the one-wavelength loop antenna is formed in a rhombus shape, and an outer dimension in the direction of the symmetry axis is formed at 1/20 wavelength of the one-wavelength loop antenna. A broadband loop antenna characterized by 2. The broadband loop antenna according to claim 1, wherein a broadband conductive metal plate or a broadband conductive metal thin film is disposed so as to cover a portion surrounded by the antenna element and the broadband element. A wideband loop antenna. A one-wavelength loop antenna is formed so that the antenna element is line-symmetric, and two adjacent points having an electrical length of ¼ wavelength from the two feeding points at the line-symmetrical position of the one-wavelength loop antenna from the feeding point. A wide band conductive metal part is formed by expanding the area of the antenna element up to a line symmetrical position inside the one-wavelength loop element, and the two wide band conductive metal parts are line symmetric. A wideband loop antenna characterized by being provided and configured as follows. 13. The broadband loop antenna according to claim 12, wherein the broadband conductive metal portion includes an edge parallel to the line-symmetric symmetry axis and an edge perpendicular to the symmetry axis. Broadband loop antenna. The outer shape is a one-wavelength loop antenna, from two feeding points that are in a line-symmetric position of the one-wavelength loop antenna to two positions that are in line symmetry near an electric length of ¼ wavelength from the feeding point. A wide band conductive metal plate or a wide band conductive metal thin film having an edge and having an enlarged area inside the one-wavelength loop antenna is provided, and the two wide band conductive metal plates or the wide band conductive metal thin film are axisymmetric. In this way, a conductive metal line or a conductive metal thin film line is used to connect between the two positions that are symmetrical with respect to the electrical length of ¼ wavelength from the two feeding points, and the broadband conductive A broadband loop antenna characterized in that an outer shape of the one-wavelength loop antenna is constituted by the edge of a metal plate or a broadband conductive metal thin film and the conductive metal wire or conductive metal thin film wire. 15. The broadband loop antenna according to claim 14, wherein the broadband conductive metal plate or the broadband conductive metal thin film includes an edge parallel to the line-symmetric symmetry axis and an edge in a direction perpendicular to the symmetry axis. A wideband loop antenna characterized by The broadband loop antenna according to claim 14 or 15, wherein an outer shape of the one-wavelength loop antenna is formed in a diamond shape.