JP2013198090A - Antenna device - Google Patents

Abstract

To provide an antenna device that can support a plurality of wireless communication systems, can ensure high antenna performance with a small antenna area, and does not require a thickness.
A second antenna element 12 is shorter than the first antenna element 11 by a predetermined length, and is disposed orthogonal to the first antenna element 11. The first and second antenna elements 11 and 12 includes a loop-shaped third antenna element 15 arranged so as to surround the first antenna element 12, and the fourth antenna elements 18 and 19 are arranged along the third antenna element 15. A first antenna composed of the second antenna elements 11 and 12 operates in a first frequency band corresponding to a wavelength approximately twice the element length of the first antenna element 11; The antenna elements 16 and 17 constitute a second antenna, and the third antenna element 15 has an inner peripheral length of approximately two wavelengths in the first frequency band and an outer peripheral length of approximately the second frequency band. One wavelength is formed.
[Selection] Figure 1

Description

  The present invention relates to an antenna device that is compatible with a plurality of wireless communication systems and is mounted on a window glass of a vehicle that transmits or receives radio waves.

  In recent years, various wireless communication systems (for example, cellular, AM / FM broadcasting, terrestrial digital broadcasting (terrestrial digital), GPS, VICS (registered trademark), ETC, etc.) have been installed in vehicles, and these have been supported. Many antennas are needed. 2. Description of the Related Art Conventionally, circularly polarized microstrip antennas such as GPS and ETC, which have been arranged on a dashboard of a vehicle, have been arranged on a front window glass as a planar antenna in recent years. Is also affixed to the front window glass.

  As such a planarly polarized antenna device mounted on a conventional front window glass, the first element and the second element are provided on the surface of the dielectric substrate with the first element and the second element. Is a slot provided in a V shape orthogonal to each other, and one of the first element and the second element is known to have a length that is longer than the other length ( For example, see Patent Document 1).

  Further, as a circularly polarized antenna device mounted on another conventional front window glass, it is a substantially square radiating element formed on one main surface of a dielectric substrate, and is opposed in one diagonal direction. A radiating element having a cut portion in which two corner portions are cut, and a ground conductor having a square opening at the center and a square outer shape, and the radiating element is disposed in the opening of the ground conductor. In addition, there is known a structure in which a gap having a predetermined width is provided with respect to the ground conductor (see, for example, Patent Document 2).

  In addition, as an antenna device corresponding to a plurality of conventional wireless communication systems, a first antenna (for terrestrial digital broadcasting) composed of a loop antenna and a second antenna (for GPS) arranged so as not to overlap the first antenna The first and second antennas each have two feeding terminals, and one feeding terminal of the first antenna and one feeding terminal of the second antenna are configured as one common feeding terminal, An antenna in which a second antenna includes a loop antenna and a non-pay element provided adjacent to one side thereof and a GPS antenna and a terrestrial digital antenna are integrated is known (see, for example, Patent Document 3).

JP 2002-26638 A WO03 / 105278 publication JP 2010-283855 A

However, in the antenna device described in Patent Document 1, although the antenna can be configured in a plane, the antenna performance is low, and in order to improve the antenna performance, it is necessary to provide a reflective element at a predetermined distance from the element, and the antenna volume There was a problem of increasing.
In addition, in the antenna devices described in Patent Documents 1 and 2, in order to support only a circularly polarized antenna such as GPS or ETC, a separate antenna is required to support a plurality of wireless communication systems. There was a problem that the volume of the antenna increased.
In addition, in the configuration described in Patent Document 3, it is difficult to cover a wideband of terrestrial digital broadcasting (13 ch to 52 ch: 473 MHz band to 707 MHz band) because the loop element is configured by a linear element. Had the problem that the gain might be low.

  The present invention has been made to solve the conventional problems, and does not require a thickness, and further, a circularly polarized antenna capable of ensuring high antenna performance with a small antenna area and a broadband terrestrial digital broadcasting. An object of the present invention is to provide an antenna device that integrates an antenna for use.

  The antenna device according to the present invention is an antenna device including first to fourth antenna elements made of a conductive material provided on the same dielectric, wherein the first, second and fourth antenna elements are provided. Has a feeding terminal at the end thereof, and the second antenna element is shorter than the first antenna element by a predetermined length and is arranged orthogonal to the longitudinal direction of the first antenna element. The third antenna element has a loop shape arranged at a predetermined interval so as to surround the first antenna element and the second antenna element, and the fourth antenna The element is arranged at a predetermined distance from the outer periphery of the third antenna element and along the outer periphery, and the first antenna configured by the first antenna element and the second antenna element. Is the first A second antenna configured to operate in a frequency band and configured by the fourth antenna element operates in a second frequency band, and the third antenna element has an inner peripheral length of the first frequency band. The outer peripheral length is formed to be approximately one wavelength of the second frequency band.

  According to the present invention, since it is an integrated antenna corresponding to a plurality of wireless communication systems, an antenna can be configured with a small area, and furthermore, a high gain and a wide band can be realized, so that a high reception sensitivity performance is exhibited. There is an effect that can.

The front view which shows the basic composition of the antenna apparatus in Embodiment 1 of this invention 1 is a configuration diagram when the antenna device according to Embodiment 1 of the present invention is mounted on a windshield of an automobile. Schematic diagram showing the antenna current distribution when the antenna device according to Embodiment 1 of the present invention operates as a circularly polarized antenna. The characteristic view which shows the effect of the directivity gain at the time of operate | moving as an antenna for circular polarization of the antenna apparatus in Embodiment 1 of this invention FIG. 5 is a characteristic diagram showing directivity gain when the antenna device according to Embodiment 1 of the present invention operates as a circularly polarized antenna. The characteristic view which shows the axial ratio at the time of operate | moving as an antenna for circular polarization of the antenna apparatus in Embodiment 1 of this invention The characteristic figure which shows VSWR at the time of operate | moving as an antenna for terrestrial digital broadcasting of the antenna apparatus in Embodiment 1 of this invention The front view which shows another shape of the antenna element of the antenna apparatus in Embodiment 1 of this invention

(Embodiment 1)
Hereinafter, a circularly polarized antenna device according to Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a basic configuration diagram of an antenna apparatus according to Embodiment 1 of the present invention.
In this embodiment, as an example of an antenna device, a case will be described in which the present invention is implemented as an integrated antenna in which a GPS antenna having a frequency of 1.575 GHz and a terrestrial digital antenna having a frequency of 473M to 707 MHz are integrated.

  The antenna device 10 in FIG. 1 includes a first antenna element 11, a second antenna element 12, a third antenna element 15, a fourth antenna element 16, and a fourth antenna element 17. The antenna device 10 is mounted on, for example, the upper side of the windshield 21 of the vehicle 20 in FIG. The power feeding unit 23 is connected to the navigation device 22 via the coaxial cable 24.

The first antenna element 11, the second antenna element 12, the third antenna element 15, the fourth antenna element 16, and the fourth antenna element 17 are all formed of a conductive material. In the present embodiment, these antenna elements are described as transparent conductive materials having a light transmittance of 80% or more, for example.
The transparent conductive material is, for example, formed of a conductive material having a thickness of 10 μm in a mesh shape on a transparent film substrate having a thickness of 100 μm, a line width of 20 μm, and a line interval of 900 μm. Is set to 0.1Ω / □ or less.

  The first antenna element 11 has a feeding terminal 13 at one end. The second antenna element 12 includes a feeding terminal 14 at one end. The power feeding terminal 13 and the power feeding terminal 14 are arranged close to each other at a predetermined interval at the end on the side where the first antenna element 11 and the second antenna element 12 are adjacent to each other.

The first antenna element 11 has an L-shaped configuration in which rectangles of equal widths extend in the X-axis positive direction (+ X-axis direction) and the Y-axis positive direction (+ Y-axis direction). The longest side among the six sides constituting the outer shape, the next long side, and the end side where the power supply terminal 13 is provided are parallel to the X axis, and the other three sides are the Y axis. They are arranged in parallel.
The second antenna element 12 is a rectangle extending in the Y-axis direction, and is arranged so that two sides in the longitudinal direction are parallel to the Y-axis.
As described above, the first antenna element 11 and the second antenna element 12 are arranged so that the long sides (longitudinal directions) of the two elements are orthogonal to each other. Therefore, the first antenna element 11 and the second antenna element 12 form a dipole antenna, and this dipole antenna operates as a GPS antenna (first antenna).

  The third antenna element 15 has a loop shape with an opening. As shown in FIG. 1 using broken lines, a part of the cutout is provided. In the notch, the vicinity of the end of the first antenna element 11 on the side where the feeding terminal 13 is provided and the vicinity of the feeding terminal 14 of the second antenna element 11 are located. The third antenna element 15 includes the first antenna element 11 and the second antenna element 12 so that one side thereof is parallel to each of the first antenna element 11 and the second antenna element 12. And a predetermined interval so as to surround the periphery. As a result, the third antenna element 15 operates as a parasitic element of a GPS antenna composed of a dipole antenna formed by the first antenna element 11 and the second antenna element 12, and also serves as a terrestrial digital antenna. Operate.

  The fourth antenna element 16 includes a feeding terminal 18 at one end thereof. The fourth antenna element 17 includes a feeding terminal 19 at one end thereof. The power feeding terminal 18 and the power feeding terminal 19 are arranged close to each other at a predetermined interval at the end on the side where the fourth antenna element 16 and the fourth antenna element 17 are adjacent to each other.

The fourth antenna element 16 is a rectangle that extends in the X-axis direction, and is arranged so that its longitudinal direction is parallel to the X-axis.
The fourth antenna element 17 has an L-shaped configuration in which rectangles of equal widths extend in the X-axis positive direction (+ X-axis direction) and the Y-axis negative direction (−Y-axis direction). The longest side of the six sides constituting the outer shape, the next longest side, and the end side where the power supply terminal 19 is provided are arranged so as to be parallel to the Y axis.
By arranging the fourth antenna element 16 and the fourth antenna element 17 as described above, the long sides (longitudinal directions) of the two elements are configured to be orthogonal. Therefore, the fourth antenna element 16 and the fourth antenna element 17 form a dipole antenna, and this dipole antenna operates as a terrestrial digital antenna (second antenna).

  Further, the first antenna element 11, the second antenna element 12, the third antenna element 15, the fourth antenna element 16, and the fourth antenna element 17 are in the + Z-axis direction (in FIG. 1). When viewed from the front side of the drawing, they are arranged so as not to overlap each other. And the 1st antenna element 11 and the 2nd antenna element 12 are arrange | positioned inside the opening surface which is an inner rectangle formed from the 3rd antenna element 15 and its notch. The fourth antenna element 16 and the fourth antenna element 17 are arranged outside an outer rectangle formed by the third antenna element 15 and its cutout. Each element is arranged on the same plane (XY plane in FIG. 1) with respect to the Z axis.

  The sum of the element length L1 of the first antenna element 11, that is, the length of the longest side among the sides parallel to the X-axis and the longest side among the sides parallel to the Y-axis is substantially a half wavelength of the operating frequency. Here, “substantially half wavelength” means within the range of 0.35 to 0.55 wavelength of the operating frequency. In the present embodiment, the element length L1 is within the above range with respect to the wavelength of the operating frequency of the GPS band.

  The element length L2 of the second antenna element 12, that is, the length in the longitudinal direction (Y-axis direction in FIG. 1) is configured to be shorter than the element length L1 of the first antenna element 11 by a predetermined length. The element length L2 shown in FIG. 1 is approximately 90% of the element length L1. That is, the element length L1 of the first antenna element 11 is longer than the element length L2 of the second antenna element 12. Further, the distance between the first antenna element 11 and the third antenna element 15 and the distance between the second antenna element 12 and the third antenna element 15 are all the same D1. This distance D1 is, for example, approximately 1/25 with respect to the wavelength of the operating frequency of the GPS band, and the third antenna element 15 is disposed close to the first antenna element 11 and the second antenna element 12. Has been. The distance D1 is a distance between adjacent sides of each element.

  The opening surface length C1 of the third antenna element 15 is approximately two wavelengths with respect to the wavelength of the operating frequency of the GPS band. Here, by setting the opening surface length C1 to approximately two wavelengths, the third antenna element 15 can achieve the function of improving the gain of the first antenna. The opening surface length C1 may be set in a range in which the third antenna element 15 exhibits such a function. Specifically, the opening surface length C1 may be set to about 1.5 to 2.5 wavelengths of the operating frequency. . The opening surface length C1 refers to the sum of the inner length from end to end, that is, the length of the inner side, not including the cutout portion of the third antenna element 15.

  The element length L3 of the fourth antenna element 16, that is, the length in the longitudinal direction (X-axis direction in FIG. 1), the element length L4 of the fourth antenna element 17, that is, the longest side among the sides parallel to the X axis, and Y The sum of the lengths of the longest side among the sides parallel to the axis is, for example, approximately ¼ wavelength with respect to the wavelength of the operating frequency of the terrestrial digital band. The distance between the fourth antenna element 16 and the third antenna element 15 and the distance between the fourth antenna element 17 and the third antenna element 15 are both D2. The distance D2 is, for example, approximately 1/150 with respect to the wavelength of the operating frequency in the terrestrial digital band, and the third antenna element 15 is disposed in the vicinity of the fourth antenna elements 16 and 17. The distance D2 refers to the distance between adjacent sides of each element.

  The outer peripheral length C2 of the third antenna element 15 is approximately one wavelength with respect to the wavelength of the high frequency band of the terrestrial digital band. Here, by setting the outer peripheral length C2 to approximately one wavelength, the third antenna element 15 operates as an antenna element in a high frequency band of the terrestrial digital band, and the frequency bandwidth of the second antenna can be expanded. The function of being able to be performed can be exhibited. The outer peripheral length C2 may be in a range in which the third antenna element 15 exhibits such a function, but specifically, it may be set to about 0.7 to 1.2 wavelengths of the operating frequency. The outer peripheral length C2 refers to the sum of the outer length from end to end, that is, the length of the outer side, not including the cutout portion of the third antenna element 15.

Since the antenna device 10 is disposed on the windshield 21 having a dielectric constant of 7, for example, the wavelength is shortened. For example, the length of L1 is 51 mm, the length of L2 is 48 mm, the length of L3 and L4 is 110 mm, The length of C1 is 210 mm, the length of C2 is 260 mm, and the distance between D1 and D2 is 4 mm.
The characteristics of the antenna device 10 configured as described above are as shown in FIGS. Each characteristic will be described later with reference to each figure.

The operation of the antenna device 10 configured as described above will be described below.
As shown in FIG. 1, the element length L1 of the first antenna element 11 is longer than the element length L2 of the second antenna element 12. For this reason, in the antenna device 10, when power is supplied to the power supply terminal 13 of the first antenna element 11 and the power supply terminal 14 of the second antenna element 12, where T is the period with respect to the operating frequency of the GPS band, T = 0 The antenna current at is distributed on the first antenna element 11 in the −X-axis direction. When T = 1/4, the antenna current is distributed on the second antenna element 12 in the −Y-axis direction. When T = 1/2, the antenna current is distributed on the first antenna element 11 in the + X-axis direction. That is, with the passage of time, the antenna current distributed on the first antenna element 11 and the second antenna element 12 is distributed clockwise with a period T toward the + Z-axis direction. At this time, the GPS antenna composed of the first antenna element 11 and the second antenna element 12 has a right-handed circularly polarized wave characteristic. Since the radio wave radiated from the GPS satellite also has a right-handed circular polarization characteristic, the radio wave from the GPS satellite can be received well.

  When power is supplied to the first antenna element 11 and the second antenna element 12, the antenna current is also distributed to the third antenna element 15 arranged close to the antenna element 11. At this time, the antenna current distributed in the antenna device 10 at a certain time is as shown in FIG. Note that the same parts as those in FIG.

  FIG. 3 is a schematic diagram showing an antenna current distribution of the antenna device according to the present embodiment. As described above, the opening surface length C1 of the third antenna element 15 is two wavelengths long with respect to the wavelength of the GPS band, and the lengths of the four sides constituting the opening of the third antenna element 15 are , Which is approximately half the wavelength of the GPS band. For this reason, for example, when the antenna current 30 is distributed in the + X-axis direction on the first antenna element 11, the antenna currents 31 to 34 are distributed in the directions of the arrows on each side of the third antenna element 15. At this time, the antenna current 30 and the antenna current 33 are distributed in the same direction, and the distance D3 between the second antenna element 12 and the side of the third antenna element 15 through which the antenna current 33 flows is approximately ½ wavelength. For this reason, radiation in the Y-axis direction is suppressed by the array effect, and radiation in the Z-axis direction becomes stronger.

  The case where the antenna current 30 is distributed to the second antenna element 12 is the same as that in FIG. In this case, the antenna current 32 flowing in the side of the third antenna element 15 whose distance from the second antenna element 12 is approximately ½ wavelength is distributed in the same direction, and radiation in the X-axis direction is caused by the array effect. Suppresses and increases the radiation in the Z-axis direction.

FIG. 4A is a diagram showing a right-handed circular polarization gain with respect to the elevation angle θ of the vertical plane (XZ plane) of the antenna device 10 with and without the third antenna element 15, and FIG. It is the figure which showed the coordinate system.
In FIG. 4A, the directivity pattern 40 indicated by a broken line indicates that there is no third antenna element 15, that is, a GPS antenna configured by the first antenna element 11 and the second antenna element 12 ( The right-handed circular polarization gain of the first antenna) is shown. A directivity pattern 41 indicated by a solid line indicates the right-handed circular polarization gain of the antenna device 10. At this time, the directivity pattern 41 has a right-handed circular polarization gain improved with respect to the directivity pattern 40 in the range of the elevation angle θ of −30 to 110 degrees, and +2 dB at the elevation angle of 0 degrees (+ Z axis direction, antenna front direction). The gain is improved and +4.0 dBi can be obtained.

FIG. 5A is a diagram showing the right-handed circular polarization gain and the left-handed circular polarization gain with respect to the elevation angle θ of the vertical plane (XZ plane) of the antenna device 10, and FIG. 5B shows the coordinate system. FIG. Note that the same parts as those in FIG.
A directivity pattern 51 indicated by a broken line indicates a left-handed circular polarization gain. As shown in FIG. 5B, the elevation angle θ, which is the maximum gain in the directivity pattern 51, is 180 degrees different from the directivity pattern 41 indicated by the solid line indicating the right-handed circular polarization gain. Thus, a good circular polarization characteristic is obtained by the antenna device 10 of the present embodiment.

6A is a diagram showing an axial ratio of the vertical plane (XZ plane) of the antenna device 10 to the elevation angle θ, and FIG. 6B is a diagram showing a coordinate system. The axial ratio in FIG. 6A is the maximum and minimum ratio of the electric field. The smaller the ratio, the closer to circular polarization, and the larger the ratio, the elliptical polarization with a larger ratio between the major axis and the minor axis.
As shown in FIG. 6A, in the axial ratio as well, when the elevation angle θ is 0 degree, it becomes 1 dB or less, and a good circular polarization characteristic is obtained.

  Therefore, as shown in FIG. 2, when the antenna device 10 is attached to the windshield 21 from the inside of the vehicle 20, the right-handed circularly polarized wave has a maximum gain in a direction orthogonal to the windshield 21. be able to. For this reason, the antenna directivity can be directed toward the GPS satellite. In addition, an antenna having a planar configuration that can be attached to the windshield 21 and having a small antenna area and a high right-handed circularly polarized gain can be realized.

  Next, as described above with reference to FIG. 1, the element lengths L3 and L4 of the fourth antenna element 16 and the fourth antenna element 17 are respectively set to wavelengths in a low frequency band of the terrestrial digital frequency band. The quarter wavelength is set. Therefore, when power is supplied to the power supply terminal 18 of the fourth antenna element 16 and the power supply element 19 of the fourth antenna element 17, it operates as a half-wave dipole antenna.

  At this time, since the third antenna element 15 is disposed close to the fourth antenna element 16 and the fourth antenna element 17, they are electromagnetically coupled to them. Furthermore, the third antenna element 15 operates as a parasitic radiation element because its outer peripheral length C2 is set to approximately one wavelength with respect to the wavelength of the high frequency band of the terrestrial digital frequency band. With the above-described action, as shown in FIG. 7, two resonances occur, and VSWR <3 can be set within the terrestrial digital band, and high radiation characteristics can be secured in the terrestrial digital band.

As described above, according to the present embodiment, an L-shaped GPS antenna that can be configured in a plane has a loop shape in which an opening surface that is not electrically connected to the GPS antenna is approximately two wavelengths with respect to the wavelength of the GPS band. By providing this element, a high-gain GPS antenna can be realized by the array effect using the GPS antenna current flowing in the loop-shaped element.
Further, the outer periphery of the loop-shaped element is set to approximately one wavelength with respect to the wavelength of the high frequency band of the terrestrial digital band, and is close to the outer periphery of the terrestrial digital band, and is ¼ of the wavelength of the low frequency band of the terrestrial digital band By providing an L-shaped two-element antenna with a wavelength, a wide band is realized by distributing the terrestrial digital antenna current to a loop-shaped element electromagnetically coupled to the L-shaped dipole antenna. A terrestrial digital antenna can be realized.

  In other words, by adjusting the element length of the loop-shaped element and the element length of the outer periphery, a single parasitic element increases the gain in the GPS band and increases the band in the terrestrial digital band, thereby reducing the size and gain. An antenna corresponding to a plurality of communication systems capable of performing high communication can be realized.

  In the present embodiment, the dipole antenna as the first antenna composed of the first antenna element 11 and the second antenna element 12 has been described as a GPS antenna, but circular polarization characteristics are required. Similar effects can be obtained even for ETC and DSRC.

In the present embodiment, the second antenna constituted by the fourth antenna element 16 and the fourth antenna element 17 has been described as an L-shaped dipole antenna for terrestrial digital broadcasting. However, the shape of the antenna element is not limited to this.
FIG. 8 is a front view showing another shape of the antenna element in the antenna device according to the first embodiment of the present invention. For example, an antenna element for terrestrial digital broadcasting can be configured as shown in FIG. The antenna device 80 including the antenna element shown in FIG. 8 can also obtain substantially the same effect as the antenna device 10.

  The antenna device 80 includes a fourth antenna element 81 instead of the fourth antenna element 16 and the fourth antenna element 17 of the antenna device 10. The fourth antenna element 81, like the fourth antenna element 16 and the fourth antenna element 17, has two element lengths that are approximately ¼ of the wavelength of the operating frequency in the terrestrial digital frequency band. It is not a configuration in which the elements are arranged orthogonally, but has a loop shape with a notch part of which is removed, and is arranged so as to surround the third antenna element 15. And the sum L5 of the length of the outer side from the end to the end is formed so as to be substantially one wavelength with respect to the terrestrial digital frequency band. For this reason, by supplying power between the power supply terminals 82 and 83 of the fourth antenna element 81 provided at both ends, substantially the same effect as the antenna device 10 can be obtained.

  Moreover, in this Embodiment, the antenna comprised by the 3rd antenna element 15, the 4th antenna element 16, and the 4th antenna element 17 was demonstrated as an object for terrestrial digital. However, regardless of this, the element length of the third antenna element 16 and the fourth antenna element 17 is 1/4 wavelength of the 2 GHz band for cellular, and the outer periphery of the third antenna element 15 is 800 MHz band for cellular. If it is set to have one wavelength, it operates as an integrated antenna of the GPS band and the cellular band.

  In the present embodiment, the feeding terminal 13 of the first antenna element 11, the feeding terminal 14 of the second antenna element 12, the feeding terminal 18 of the fourth antenna element 16, and the feeding terminal of the fourth antenna element 17 are used. The example which comprised 19 separately was shown. However, even if the feeding terminal 13 of the first antenna element 11 and the feeding terminal 18 of the fourth antenna element 16 are electrically connected, the same effect as the antenna device 10 can be obtained.

  Further, in the present embodiment, the transparent conductive material has been described as a mesh configuration, but regardless of this, if the sheet resistance is 0.1 Ω / □ or less and the light transmittance is 80% or more, Similar effects can be obtained. The light transmittance refers to the total light transmittance measured by a method according to JIS-K-7105 and JIS-K-7361 using a haze meter.

  Since the antenna device of the present invention is an integrated antenna that supports a plurality of wireless communication systems, the antenna can be configured with a small area, and further, high gain and wide bandwidth can be realized, so that high reception sensitivity performance is exhibited. For example, it is useful for an antenna device mounted on a vehicle windshield.

DESCRIPTION OF SYMBOLS 10, 80 Antenna apparatus 11 1st antenna element 12 2nd antenna element 13, 14 Feed terminal 15 3rd antenna element 16, 17 4th antenna element 18, 19 Feed terminal 20 Vehicle 21 Windshield 22 Navigation apparatus 23 Feeder 24 Coaxial cable 30 Antenna current on first antenna element 31, 32, 33, 34 Antenna current on parasitic element 40, 41, 51 Directional pattern 81 Fourth antenna element 82, 83 Feed terminal

Claims (4)

In the antenna device including the first to fourth antenna elements made of a conductive material provided on the same dielectric,
The first, second and fourth antenna elements are provided with feeding terminals at their ends,
The second antenna element is shorter than the first antenna element by a predetermined length, and is disposed orthogonal to the longitudinal direction of the first antenna element.
The third antenna element has a loop shape arranged at a predetermined interval from the first antenna element and the second antenna element so as to surround the first antenna element and the second antenna element.
The fourth antenna element is arranged at a predetermined distance from the outer periphery of the third antenna element and along the outer periphery.
A first antenna constituted by the first antenna element and the second antenna element operates in a first frequency band;
A second antenna constituted by the fourth antenna element operates in a second frequency band;
The third antenna element is formed so that an inner peripheral length thereof is approximately two wavelengths in the first frequency band, and an outer peripheral length is approximately one wavelength in the second frequency band. An antenna device.   The said 4th antenna element is comprised by the two antenna elements arrange | positioned orthogonally whose element length is substantially 1/4 wavelength of the said 2nd frequency band. The antenna device according to 1.   3. The antenna device according to claim 2, wherein an element length of the first antenna element is substantially a half wavelength of the first frequency band, and the first antenna is a circularly polarized antenna. 4. The antenna device according to claim 3, wherein the first to fourth antenna elements are made of a transparent conductive material having a light transmittance of 80% or more.