JP4732222B2 - Antenna device - Google Patents

Description

  The present invention relates to a low-profile antenna apparatus that exhibits wideband gain characteristics with directivity.

  2. Description of the Related Art Conventionally, an antenna of a portable radio device including a waveguide electrode for improving radiation efficiency is known. A partial cross-sectional view showing the configuration of this antenna is shown in FIG. In the partial cross-sectional view of the portable wireless device shown in FIG. 20, reference numeral 111 denotes a casing of the portable wireless device, which is made of, for example, a synthetic resin. A printed circuit board 102 on which a high-frequency circuit is disposed is housed in a housing 111, and a box-shaped dielectric substrate 103 is covered on one surface of the printed circuit board 102. A ground electrode 105 serving as a shield plate is provided over almost the entire inner surface of the dielectric substrate 103, and the ground electrode 105 is electrically connected to a ground circuit provided on the printed circuit board 102, so that a high-frequency circuit is provided. The area is electrically shielded. A radiator 106 made of a microstrip line is provided on the outer surface of the dielectric substrate 103. The radiator 106 is connected to an antenna on the surface of the printed circuit board 102 by a conductive wire 107 that penetrates the dielectric substrate 103 and the ground electrode 105. Connected to the end. With this structure, the dielectric substrate 103, the ground electrode 105, and the radiator 106 constitute a microstrip antenna. Reference numeral 108 denotes a waveguide electrode provided on the inner surface of the casing 111 so as to face the radiator 106. The waveguide electrode 108 functions as a director for the radiator 106, and improves the radiation efficiency of the microstrip antenna.

In the antenna configured as described above, the waveguide electrode 108 not only improves the radiation efficiency of the microstrip antenna, but also has the effect of extending the frequency band. For example, the resonant wavelength of the waveguide electrode 108 and the radiator 106 is slightly changed by means such as changing the size of the waveguide electrode 108 and the size of the radiator 106, and the radiator 106 is used in a short wavelength region of the operating frequency band. If the waveguide electrode 108 is resonated in the long wavelength region of the use frequency band, a relatively uniform radiation efficiency can be obtained over the entire use frequency band. In other words, the operating frequency range can be expanded as compared with the case where the waveguide electrode 108 is not provided.
Japanese Utility Model Publication No. 4-103006

  In the conventional antenna shown in FIG. 20, the radiation efficiency and the usable frequency range can be expanded by the action of a radiator composed of a microstrip line and a waveguide provided in front of the radiator. However, in the conventional antenna, the resonant wavelength of the waveguide electrode 108 and the radiator 106 can only be changed slightly, and the extended operating frequency range is a limited frequency range, and the antenna operates well over a wide band. There was a problem that could not be done. Further, the conventional antenna has a problem that the directivity cannot be varied because the directivity is fixed.

  Therefore, an object of the present invention is to provide an antenna device that operates well over a wide band.

In order to achieve the above object, an antenna device according to the present invention includes a shorting plate having one end connected to a ground plate, and a power feeding unit including a power feeding element extending substantially parallel to the ground plate from the other end of the short plate. And a flat plate-like radiating element that covers the entire surface of the power supply unit disposed substantially in parallel with a predetermined gap on the power supply unit, and the wavelength of the low frequency f1 of the use frequency band is λ1, and the frequency of the high frequency f2 When the wavelength of λ2 is λ2, the length of the feed element is about 0.13λ1 to about 0.26λ1, and the distance from the short plate to the position where power is fed in the feed element is about 0.04λ2 to about 0. The most important point is that the long side of the radiating element has a length of about 0.43λ2 to about 0.54λ2, and the ground plate is larger than the radiating element. It is a feature.

The antenna device according to the present invention includes a power supply unit including a short plate having one end connected to the ground plate, a power supply element extending substantially parallel to the ground plate from the other end of the short plate, and a predetermined gap on the power supply unit. And a flat plate-like radiating element that covers the entire surface of the power supply unit disposed substantially in parallel, and the wavelength of the low frequency f1 of the operating frequency band is λ1, and the wavelength of the high frequency f2 is λ2. The length of the feed element is about 0.13λ1 to about 0.26λ1, and the distance from the short plate to the position where power is fed in the feed element is about 0.04λ2 to about 0.17λ2 , Since the length of the long side of the element is about 0.43λ2 to about 0.54λ2, and the earth plate is larger than the radiating element, the antenna device operates well over a wide band. Can be ground de An antenna device suitable as an antenna for digital broadcasting can be obtained.

The configuration of the antenna device according to the first embodiment of the present invention is shown in FIGS. 1 is a perspective view showing the configuration of the antenna device of the present invention, and FIG. 2 is a side view showing the configuration of the antenna device of the first embodiment of the present invention.
In the antenna device 1 of the first embodiment shown in these drawings, an earth plate 10 made of a metal plate having a horizontally long rectangular plate shape and a metal plate provided on the earth plate 10 are formed in an L shape. The power supply unit 11 is formed by bending, and the radiating element 13 is formed on the power supply unit 11 through a predetermined gap and is formed of a horizontally long rectangular flat metal plate. ing. One end of the L-shaped power feeding portion 11 is electrically connected to the ground plate 10, a short plate 11 a erected substantially perpendicular to the ground plate 10, and the other end of the short plate 11 a. It is formed of an elongated feeding element 11 b that is bent substantially orthogonally and extends substantially parallel to the ground plate 10. The other end of the power feeding element 11b is open, and power is fed by a coaxial cable 12 to a predetermined position of the power feeding element 11b. In this case, the outer conductor of the coaxial cable 12 is electrically connected to the ground plate 10, and the central conductor of the coaxial cable 12 is electrically connected to the power feeding element 11b.

  The ground plate 10, the power feeding unit 11, and the radiating element 13 are formed using a metal plate such as a copper plate having a thickness of about 0.5 mm. For example, the ground plate 10 and the power feeding unit are made of foamed polystyrene having a relative dielectric constant of approximately 1. 11 and the radiating element 13 are fixed as shown. Further, the ground plate 10, the power feeding part 11, and the radiating element 13 may be formed by vapor-depositing metal or depositing metal foil on an insulating substrate. Furthermore, the earth plate 10, the power feeding part 11, and the radiating element 13 may be fixed by an insulating support base such as a resin, or may be fixed by clamping or screws at the time of fixing. One short side of the radiating element 13 is arranged so as to substantially match the arrangement position of the short plate 11a, but may be installed so as to protrude from the short plate 11a. However, the dimension of the long side of the radiation element 13 protruding from the short plate 11a is not included in the design dimension. Moreover, although the arrangement | positioning position of the electric power feeding element 11b is arrange | positioned in the position covered with the radiating element 13, as long as it is covered with the radiating element 13, you may move within the arrangement | positioning surface. Further, the coaxial cable 12 is used for supplying power to the power supply element 11b. In addition to this, power is supplied through a microstrip line or a coplanar line formed on the printed board by forming the ground plate 10 with the printed board. It may be.

FIG. 3 is an exploded view showing a perspective view of the configuration of the antenna device 1 according to the first embodiment of the present invention. As shown in FIG. 3, a power feeding unit 11 including a short plate 11 a and a power feeding element 11 b is disposed on a rectangular ground plate 10, and one end of the short plate 11 a is electrically and mechanically connected to the ground plate 10. Connected. The coaxial cable 12 supplies power to a predetermined position of the power feeding element 11b. And the antenna device 1 can be assembled by arrange | positioning the rectangular radiation | emission element 13 on the electric power feeding part 11 via a predetermined gap | interval as shown by the arrow.
In the antenna device 1 according to the first embodiment of the present invention, the frequency band extending from the low frequency f1 to the high frequency f2 is used, the wavelength of the frequency f1 is λ1, and the wavelength of the frequency f2 is λ2. In this case, the length of the feed element is set to a length determined in accordance with a low frequency within a predetermined range substantially centered on λ1 / 4, and the distance from the short plate to the predetermined position where power is fed in the feed element is λ2 / The distance is determined according to the wavelength of the high frequency in the predetermined range centered at 10 and the wavelength of the high frequency in the predetermined range where the length of the long side of the radiating element is approximately λ2 / 2. And the ground plate is larger than the radiating element. With this configuration, the antenna device 1 according to the first embodiment of the present invention exhibits good electrical characteristics over a use frequency band that is a wide band of the frequency f1 to the frequency f2. The antenna device 1 according to the first embodiment of the present invention emits horizontally polarized waves in the Z direction which is perpendicular to the radiating element 13 shown in FIGS.

  An example of the physical dimensions of the antenna device 1 according to the first embodiment of the present invention will be described below with reference to FIG. In this case, the antenna device 1 is an antenna for digital terrestrial broadcasting, and the used frequency band is set to 500 MHz to 650 MHz in which channels are actually allocated. In order to obtain good electrical characteristics over such a wide band, the long side length L1 of the ground plate 10 is about 290 mm, the short side length W1 is about 100 mm, and the height h1 and width of the short plate 11a. Is about 10 mm, the length L2 of the long side of the power feeding element 11b is about 140 mm, and the length W2 of the short side is about 10 mm. The distance a from the short plate 11a where the central conductor of the coaxial cable 12 is connected to the feeding element 11b is about 48 mm, the long side length L3 of the radiating element 13 is about 230 mm, and the short side length W3 is 50 mm. Further, the gap h2 between the feeding element 11b and the radiation element 13 is about 10 mm. Thereby, the antenna height of the antenna device 1 is about 20 mm, and the antenna height can be a low-profile antenna device corresponding to about 0.03 wavelength of a low frequency of 500 MHz in the use frequency band.

In the antenna device 1 having the dimensions described above, horizontal polarization is radiated in the Z direction perpendicular to the radiating element 13, and the radiation patterns corresponding to the frequency of the ZY plane are shown in FIGS. Show. However, in each radiation pattern, the maximum value is normalized to 0 dB.
FIG. 4 shows a radiation pattern on the ZY plane when the frequency is 500 MHz, with a maximum gain in the + Z-axis direction, a half-value angle of about 70 degrees, and an F / B (front / back) ratio of about 20 dB. A simple radiation pattern is obtained. FIG. 5 shows a radiation pattern on the ZY plane when the frequency is 560 MHz. A radiation pattern having a maximum gain in the + Z-axis direction, a half-value angle of about 70 degrees, and an F / B ratio of about 14 dB is obtained. Yes. FIG. 6 is a radiation pattern on the ZY plane when the frequency is 620 MHz, and a radiation pattern having a maximum gain in the + Z-axis direction, a half-value angle of about 60 degrees, and an F / B ratio of about 10 dB is obtained. Yes. FIG. 7 shows a radiation pattern on the ZY plane when the frequency is 650 MHz. A radiation pattern having a maximum gain in the + Z-axis direction, a half-value angle of about 60 degrees, and an F / B ratio of about 8 dB is obtained. Yes. In this way, a large half-value angle of at least 60 degrees can be obtained over the used frequency band.

Next, FIG. 8 shows the frequency characteristics of the gain in the Z-axis direction in the antenna device 1 when the dimensions are as described above.
Referring to FIG. 8, in the antenna device 1 according to the present invention, a gain of about 1.3 dB to about 3.0 dB is obtained in a wide frequency band where the specific band from 500 MHz to 650 MHz is about 26%. In the antenna device 1 according to the present invention, the frequency band in which a gain of 0 dB or more can be obtained is about 470 MHz to about 680 MHz, and the frequency band is as wide as about 36.5%.

Next, in order to explain the operation of the radiating element 13 of the antenna device 1 according to the present invention, in the antenna device 1 shown in FIGS. 1 to 3, the radiating element 13 is removed and the Z in the antenna device having the configuration shown in FIG. The frequency characteristics of the gain in the axial direction are shown in FIG. 9 in comparison with the antenna device 1 according to the present invention. Note that the dimensions of each part in the antenna having the configuration shown in FIG. 11 are the same as those of the antenna device 1 described above.
Referring to FIG. 9, in the frequency characteristic of the gain of the antenna including only the ground plate 10, the short plate 11a, and the feeding element 11b with the radiating element 13 removed from the antenna device 1 according to the present invention, the antenna device 1 according to the present invention. The gain is lower than about 7 dB. From this, it can be seen that the power feeding element 11b has almost no function as a radiating element and mainly plays a role of feeding power to the radiating element 13.

  Next, the frequency characteristic of the gain in the Z-axis direction in a conventional inverted-F antenna, which is a typical example of a low-profile antenna, is compared with the antenna device 1 according to the present invention. An example of the configuration of the inverted F-type antenna to be compared is shown in FIG. An inverted F-type antenna 200 shown in FIG. 12 includes a rectangular flat plate ground plate 210, one end connected to the ground plate 210, and a short plate 211 a erected substantially perpendicular to the ground plate 210. The short plate 211 a is bent from the other end substantially orthogonally, and is composed of a rectangular flat plate-like radiating element 213 extending substantially parallel to the ground plate 210. In the radiating element 213, power is supplied by the coaxial cable 212 at a position b1 away from the short plate 211a. In this case, the outer conductor of the coaxial cable 212 is electrically connected to the ground plate 210, and the central conductor of the coaxial cable 212 is connected to the radiating element 213. In this inverted F-type antenna 200, the dimensions of the ground plate 210 and the radiating element 213 are the same as those of the ground plate 10 and the radiating element 13 of the antenna device 1 according to the present invention, and the short plate 211a is as wide as the short plate 11a. Although the same, the height is about 20 mm. Accordingly, the height of the radiating element 213 with respect to the ground plate 210 in the inverted F-type antenna 200 is the same as the height of the radiating element 13 with respect to the ground plate 10 in the antenna device 1 according to the present invention. In the inverted F-type antenna 200, the distance b1 is a distance optimized for the high gain of the inverted F-type antenna, and is about 20 mm.

The frequency characteristic of the gain in the Z-axis direction in the inverted F-type antenna 200 shown in FIG. 12 is shown as “conventional example 1” in FIG. Referring to the frequency characteristic of “conventional example 1” shown in FIG. 12, the maximum gain is about 1.5 dB, but the frequency band having a gain of 0 dB or more is a specific band of only about 4%. Thus, it can be seen that when the inverted-F antenna is optimized for high gain, the frequency band of the gain becomes narrow, and only a few percent of the ratio band can be obtained.
FIG. 13 shows the configuration of an inverted F-type antenna 201 that is optimized so that the gain is the widest band in the inverted F-type antenna 200 shown in FIG. In the inverted F-type antenna 201 shown in FIG. 13, except for a configuration in which the distance b2 from the short plate 211a in the radiating element 213 fed by the coaxial cable 212 is about 60 mm and the gain is optimized to have the widest bandwidth. Thus, the configuration is the same as that of the inverted F-type antenna 200. The frequency characteristic of the gain in the Z-axis direction in the inverted F-type antenna 201 shown in FIG. 13 is shown as “conventional example 2” in FIG. Referring to the frequency characteristic of “conventional example 2” shown in FIG. 12, the maximum gain is only about −3.5 dB, and the frequency characteristic of the gain is broad, but the ratio band that is set to −5 dB or more. However, only about 8% is obtained. As described above, in the conventional inverted-F antenna, when the gain is optimized to be a wide band, the gain becomes small, and the frequency band of the gain is much higher than the frequency characteristic of the gain of the antenna device 1 according to the present invention. It turns out that it does not reach.

  Note that the antenna shape of the antenna device 1 according to the present invention is not limited to a flat rectangular shape as shown in FIGS. 1 to 3, but may be configured as a spherical shape or a curved shape. Set within the range that does not exceed the long side. Furthermore, each element may be made lighter by making a hole with a shape that is much smaller than the wavelength of the operating frequency, such as a rectangle or a circle, and the side length is cut out to create a perimeter. May be changed. Further, a matching circuit using a coil L, a capacitor C, or the like may be inserted between the central conductor of the coaxial cable 12 and the feeding point of the feeding element 11b.

Next, FIG. 14 shows the frequency characteristic of the gain in the Z-axis direction when the length L3 of the long side of the radiating element 13 is used as a parameter in the antenna device 1 according to the present invention. Incidentally, as shown in FIG. 8, in the antenna apparatus 1 according to the present invention, the maximum gain of about 3 dB is obtained at a frequency of 500 MHz, which is a low frequency of the use frequency band. In the case of an antenna device into which a booster is inserted, it is sufficient that the maximum gain of the antenna device is about −2 dB within the use frequency band, and when the antenna gain is insufficient, the booster may be compensated. Therefore, the gain within the used frequency band is sufficient if the difference between the maximum gain and the minimum gain is within 5 dB. Therefore, the vertical axis represents the gain difference in the frequency characteristics of the gain shown in FIG.
In the frequency characteristics of the gain in the Z-axis direction shown in FIG. 14, the frequency band from the low frequency 500 MHz (f1) to the high frequency 650 MHz (f2) is used as the frequency band to be used, the wavelength of the frequency f1 is λ1, and the frequency f2 The length L3 of the long side of the radiating element 13 is about 0.43λ2, about 0.46λ2, about 0.48λ2, about 0.50λ2, about 0.52λ2, and about 0.54λ2. The case is shown. The frequency characteristic of the gain in the Z-axis direction shown in FIG. 8 is when the length L3 is about 0.50λ2. Referring to FIG. 14, the reason why the gain difference of 5 dB can be secured in the frequency characteristic of the gain in the Z-axis direction is that the long side length L3 of the radiating element 13 is in the range of about 0.43λ2 to about 0.54λ2. It turns out that this is the case. In this case, since the earth plate 10 may be larger than the radiation element 13, the earth plate 10 may be larger than about 0.43λ2 of the wavelength λ2 of the high frequency.

Next, FIG. 15 shows the frequency characteristics of the gain in the Z-axis direction when the antenna device 1 according to the present invention uses the length L2 of the long side of the feed element 11b as a parameter. For the reasons described above, the vertical axis represents the gain difference in the frequency characteristics of the gain shown in FIG.
In the frequency characteristic of the gain in the Z-axis direction shown in FIG. 15, when the wavelength of the frequency f1 is λ1 and the wavelength of the frequency f2 is λ2, the length L2 of the long side of the feed element 11b is about 0.18λ1. , About 0.20λ1, about 0.23λ1, about 0.26λ1, about 0.28λ1, and about 0.30λ1. The frequency characteristic of the gain in the Z-axis direction shown in FIG. 8 is when the length L2 is about 0.23λ1. Referring to FIG. 15, the reason why the gain difference of 5 dB can be secured in the frequency characteristic of the gain in the Z-axis direction is that the long side length L2 of the feed element 11b is in the range of about 0.13λ1 to about 0.26λ1. It turns out that this is the case.

Next, FIG. 16 shows the frequency characteristics of the gain in the Z-axis direction when the distance a from the short plate 11a to the position where power is fed by the feeding element 11b is used as a parameter in the antenna device 1 according to the present invention. For the reasons described above, the vertical axis represents the gain difference in the frequency characteristics of the gain shown in FIG.
In the frequency characteristic of the gain in the Z-axis direction shown in FIG. 16, when the wavelength of the frequency f1 is λ1 and the wavelength of the frequency f2 is λ2, the distance from the short plate 11a to the position where power is fed in the feed element 11b The case where a is about 0.04λ2, about 0.06λ2, about 0.08λ2, about 0.10λ2, about 0.13λ2, about 0.15λ2, and about 0.17λ2 is shown. The frequency characteristic of the gain in the Z-axis direction shown in FIG. 8 is when the distance a is about 0.10λ2. Referring to FIG. 16, the gain difference of 5 dB can be secured in the frequency characteristic of the gain in the Z-axis direction because the distance a from the short plate 11a to the position where power is fed in the feed element 11b is about 0.04λ2 to about 0. It can be seen that the range is 17λ2.

  As described above, in the antenna device 1 according to the first embodiment of the present invention, the length L2 of the feed element 11b is set in the range of about 0.18λ1 to about 0.30λ1, and the short plate 11a to the feed element 11b The distance a to the position to be fed may be in the range of about 0.04λ2 to about 0.17λ2, and the long side length L3 of the radiating element 13 may be in the range of about 0.43λ2 to about 0.54λ2. Moreover, since the earth plate 10 may be larger than the radiation element 13, the long side length L1 of the earth plate 10 may be set to be equal to or longer than the length L2 of the power feeding element 11b. In the above-mentioned frequency band, the antenna height (h1 + h2) from the ground plate 10 to the radiating element 13 is about 20 mm, and has a very low attitude of only 0.03λ1 with respect to the wavelength λ1 of the low frequency 500 MHz (f1). Thus, the antenna device 1 having a good gain over a wide band can be realized.

Next, a perspective view showing the configuration of the antenna device 2 according to the second embodiment of the present invention is shown in FIG.
The antenna device 2 of the second embodiment shown in FIG. 17 includes an insulating substrate 24 such as a glass epoxy substrate, and the antenna device 2 is provided on one surface of the substrate 24. In other words, a ground plate 20 made of a metal plate having a horizontally long rectangular plate is erected substantially vertically on the substrate 24, and the metal plate is bent on the ground plate 20 in an L shape. A power feeding unit 21 is provided. Further, a radiating element 23 made of a metal plate having a rectangular flat plate shape that is long in parallel with a predetermined gap is provided on the power supply unit 21 so as to stand substantially vertically on the substrate 24. One end of the L-shaped power feeding portion 21 is electrically connected to the ground plate 20, and a short plate 21 a erected substantially perpendicular to the ground plate 20 and the other end of the short plate 21 a. It is formed of an elongated feeding element 21b that is bent substantially orthogonally and extends substantially parallel to the ground plate 20. The other end of the power feeding element 21b is open, and power is fed by a power feeding line 22 formed on one surface of the substrate 24 at a predetermined position of the power feeding element 21b. In this case, a ground conductor is formed on the back surface of the substrate 24 so as to face the power supply line 22, and the power supply line 22 is a microstrip line.

The ground plate 20, the power feeding portion 21 and the radiating element 23 are formed using a metal plate such as a copper plate having a thickness of about 0.5 mm. For example, the ground plate 20 and the power feeding portion are made of foamed polystyrene having a relative dielectric constant of approximately 1. 21 and the radiating element 23 are fixed to the substrate 24 as shown. Alternatively, the ground plate 20, the power feeding unit 21, and the radiating element 23 may be formed by vapor-depositing metal or depositing metal foil on an insulating substrate. Further, the ground plate 20, the power feeding unit 21, and the radiating element 23 may be fixed to the substrate 24 with an insulating support such as a resin, or may be fixed by clamping or screws when fixing.
Thus, the antenna device 2 of the second embodiment has the same configuration as that of the antenna device 1 of the first embodiment, except that the antenna device 2 is arranged substantially vertically on the substrate 24. Thus, the antenna device 2 according to the second embodiment of the present invention radiates horizontally polarized waves in the X direction which is horizontal with respect to the substrate 24 shown in FIG. Further, in the antenna device 2 of the second embodiment, the long side of the radiating element 23 is installed perpendicular to the ground, and the short side thereof is installed horizontally with respect to the ground, so that the vertical polarization is set in the X direction. It is also possible to radiate.

  The dimensions of the antenna device 2 of the second embodiment are the same as those of the antenna device 1 of the first embodiment. When the frequency band from the low frequency f1 to the high frequency f2 is used as the frequency band to be used, the frequency When the wavelength of f1 is λ1 and the wavelength of frequency f2 is λ2, the length of the power feeding element 21b is about 0.18λ1 to about 0.30λ1, and the distance from the short plate 21a to the position where power is fed in the power feeding element 21b is The length of the long side of the radiating element 23 is about 0.43λ2 to about 0.54λ2 from about 0.04λ2 to about 0.17λ2. Thus, in the antenna device 2 of the second embodiment, the length of the feed element is set to a length determined according to a low frequency within a predetermined range that is substantially centered on λ1 / 4. The distance to the predetermined position to be fed is a distance determined according to the wavelength of the high frequency in a predetermined range centered on λ2 / 10, and the length of the long side of the radiating element is approximately centered on λ2 / 2 The length is determined according to the wavelength of the high frequency within a predetermined range, and the ground plate is larger than the radiating element. With this configuration, the antenna device 2 according to the second embodiment of the present invention exhibits the same frequency characteristics of the radiation pattern and gain as the antenna device 1 of the first embodiment described above, and has a wide frequency band from frequency f1 to frequency f2. It exhibits good electrical characteristics over the operating frequency band.

Next, FIG. 18 is a plan view showing the configuration of the antenna device 3 of the third embodiment of the present invention that can switch the directivity using the antenna device 2 of the second embodiment.
The antenna device 3 of the third embodiment includes four antennas, a first antenna 3-1 to a fourth antenna 3-4, which are arranged so as to be orthogonal to each other. The configuration of the first antenna 3-1 to the fourth antenna 3-4 is the same as that of the antenna device 2 of the second embodiment. The antenna device 3 includes a substrate 34 such as a rectangular glass epoxy substrate, and is provided with a rectangular cylindrical ground plate 30 that is erected substantially orthogonal to one surface of the substrate 34. A first antenna 3-1 to a fourth antenna 3-4 are provided in which the four wall surfaces of the upright rectangular tubular ground plate 30 are ground substrates.

  That is, a power feeding unit 31-1 formed by bending a metal plate in an L shape outside the first wall surface of the ground plate 30 is provided. Further, a radiating element 33-1 made of a metal plate that is a rectangular flat plate that is horizontally long and substantially parallel to the power supply unit 31-1 with a predetermined gap is erected substantially vertically on the substrate. One end of the L-shaped power feeding section 31-1 is electrically connected to the outer surface of the first wall surface of the ground plate 30, and is short-circuited substantially perpendicular to the outer surface of the first wall surface. A plate 31a-1 and an elongated feeding element 31b-1 which is bent substantially orthogonally from the other end of the short plate 31a-1 and extends substantially parallel to the outer surface of the first wall surface of the ground plate 30. It consists of and. The other end of the power feeding element 31b-1 is open, and power is fed by a power feeding line 32-1 formed on one surface of the substrate 34 at a predetermined position of the power feeding element 31b-1. In this case, a rectangular ground conductor 36 indicated by a broken line having substantially the same area as the occupied area of the rectangular cylindrical ground plate 30 is formed on the back surface of the substrate 34, and the feed line 32-1 is a microstrip line. Has been. Thus, the first antenna device 3-1 is provided outside the first wall surface of the ground plate 30.

  Further, a second antenna device 3-2 is provided outside the second wall surface of the ground plate 30. The second antenna device 3-2 has the same configuration as that of the first antenna device 3-1, and is composed of a second wall surface of the ground plate 30, a short plate 31a-2, and a feeding element 31b-2. It is comprised from the character-shaped electric power feeding part 31-2 and the radiation | emission element 33-2. Power is fed to a predetermined position of the feed element 31b-2 by a feed line 32-2, which is a microstrip line formed on one surface of the substrate. Furthermore, a third antenna device 3-3 is provided outside the third wall surface of the ground plate 30. The third antenna device 3-3 has the same configuration as the first antenna device 3-1, and is composed of a third wall surface of the ground plate 30, a short plate 31a-3, and a feeding element 31b-3. It is comprised from the character-shaped electric power feeding part 31-3 and the radiation | emission element 33-3. Power is fed to a predetermined position of the feed element 31b-3 by a feed line 32-3 that is a microstrip line formed on one surface of the substrate. Furthermore, a fourth antenna device 3-4 is provided outside the fourth wall surface of the ground plate 30. The fourth antenna device 3-4 has the same configuration as the first antenna device 3-1, and is composed of a fourth wall surface of the ground plate 30, a short plate 31a-4, and a feeding element 31b-4. It is comprised from the character-shaped electric power feeding part 31-4 and the radiation | emission element 33-4. Power is fed to a predetermined position of the feed element 31b-4 by a feed line 32-4 which is a microstrip line formed on one surface of the substrate 34.

  The dimensions of the first antenna 3-1 to the fourth antenna 3-4 in the antenna device 3 of the third embodiment are the same as those of the antenna device 2 of the second embodiment, and the frequency from the low frequency f1 to the high frequency. When the frequency band extending over f2 is the use frequency band, and the wavelength of the frequency f1 is λ1 and the wavelength of the frequency f2 is λ2, the length of the feed elements 31b-1 to 31b-4 is about 0.18λ1 to about 0. 30λ1, and the distance from the short plates 31a-1 to 31a-4 to the positions where power is fed in the power feeding elements 31b-1 to 31b-4 is about 0.04λ2 to about 0.17λ2, and the radiation elements 33-1 to 33-1 The length of the long side 33-4 is about 0.43λ2 to about 0.54λ2. As described above, the first antenna 3-1 to the fourth antenna 3-4 in the antenna device 3 of the third embodiment also have a low frequency within a predetermined range in which the length of the feed element is substantially centered on λ1 / 4. The distance from the short plate to the predetermined position where power is supplied by the power supply element is determined according to the wavelength of the high frequency within a predetermined range about λ2 / 10. The length of the long side of the element is set to a length determined according to the wavelength of a high frequency within a predetermined range substantially centered on λ2 / 2, and the ground plate is made larger than the radiating element. It is characterized by. With this configuration, the first antenna 3-1 to the fourth antenna 3-4 in the antenna device 3 according to the third embodiment of the present invention have the same radiation pattern and gain as those of the antenna device 1 according to the first embodiment described above. The frequency characteristics are exhibited, and good electrical characteristics are exhibited over a use frequency band which is a wide frequency band from the frequency f1 to the frequency f2.

  In the antenna device 3, feed lines 32-1 to 32-4 respectively led out from the first antenna 3-1 to the fourth antenna 3-4 are introduced into the control unit 35. The control unit 35 switches the directivity characteristics of the antenna device 3 by selecting an antenna to be fed from the first antenna 3-1 to the fourth antenna 3-4. From the first antenna 3-1 to the fourth antenna 3-4 in the antenna device 3, horizontally polarized waves are radiated in a direction horizontal to the substrate 34. For example, when the first antenna 3-1 is selected and fed by the control unit 35, the directivity characteristic of the antenna device 3 is upward in the paper of FIG. When the second antenna 3-2 is selected and fed by the control unit 35, the directivity characteristic of the antenna device 3 is rightward on the paper surface of FIG. Further, when the third antenna 3-3 is selected and fed by the control unit 35, the directivity characteristic of the antenna device 3 is downward on the paper surface of FIG. 18. When the fourth antenna 3-4 is selected and fed by the control unit 35, the directivity characteristic of the antenna device 3 becomes the left direction on the paper surface of FIG.

As described above, in the antenna device 3 according to the third embodiment of the present invention, at least 60 degrees can be obtained as the half-value angle in the use frequency band, so that the directivity is switched to be directed in any direction in the horizontal plane. Will be able to. An example of the configuration of the control unit 35 is shown in FIG. The control unit 35 includes a switch having a movable contact a connected to a power supply 37 and fixed contacts b, c, d, e to which the first antenna 3-1 to the fourth antenna 3-4 are connected. Has been. Here, when the movable contact a is switched to the fixed contact b, power is supplied from the power supply 37 to the first antenna 3-1. Similarly, by switching the movable contact a to the fixed contacts c, d, e, the antenna device 3 of the third embodiment is controlled by the control unit 35 according to the direction in which the radio wave arrives, from the first antenna 3-1 to the fourth antenna. By selecting any one of 3-4, the antenna device 3 operates with the optimum directivity. In this case, impedance adjustment may be performed using a matching circuit such as a coil L or a capacitor C, or fine directivity control may be performed using a phase shifter or a combiner.
In the antenna device 3, the feed line 32-1 to the feed line 32-4 may be a coplanar line. Further, in the antenna device 3 of the third embodiment shown in FIG. 18, the ground plate 30 has a rectangular cross-sectional shape. However, as a polygon, a plurality of antennas each serving as a unit on the outside of each polygonal wall portion are used. As described above, any one of the antennas may be selected by the control unit 35.

  In the embodiment of the antenna device according to the present invention described above, the antenna device has been described as an antenna device for terrestrial digital broadcasting. However, the present invention is not limited to this, and can be applied to an antenna device in which a use frequency band is wide.

It is a perspective view which shows the structure of the antenna apparatus of 1st Example of this invention. It is a side view which shows the structure of the antenna apparatus of 1st Example of this invention. 1 is an exploded view showing a configuration of an antenna apparatus according to a first embodiment of the present invention. It is a figure which shows the radiation pattern of the ZY plane in case the frequency in the antenna apparatus of 1st Example of this invention is 500 MHz. It is a figure which shows the radiation pattern of a ZY plane in case the frequency in the antenna apparatus of 1st Example of this invention is 560 MHz. It is a figure which shows the radiation pattern of the ZY plane in case the frequency in the antenna apparatus of 1st Example of this invention is 620 MHz. It is a figure which shows the radiation pattern of a ZY plane in case the frequency in the antenna apparatus of 1st Example of this invention is 650 MHz. It is a figure which shows the frequency characteristic of the gain of a Z-axis direction in the antenna apparatus of 1st Example of this invention. It is a figure which shows the frequency characteristic of the gain of a Z-axis direction for demonstrating the effect | action of a radiation element in the antenna apparatus of 1st Example of this invention. It is a figure which shows the frequency characteristic of the gain of a Z-axis direction by contrasting the antenna apparatus of 1st Example of this invention, and the conventional inverted F type antenna. It is a figure which shows the structure of the antenna which removed the radiation element in order to demonstrate the effect | action of a radiation element in the antenna apparatus of 1st Example of this invention. It is a figure which shows the structure optimized for the high gain of the conventional inverted F type antenna. It is a figure which shows the structure optimized for the broadband of the conventional inverted F type antenna. It is a figure which shows the frequency characteristic of the gain of a Z-axis direction at the time of setting the length of the long side of a radiation element as a parameter in the antenna apparatus of 1st Example of this invention. It is a figure which shows the frequency characteristic of the gain of a Z-axis direction when the length of the long side of a feed element is made into the parameter in the antenna apparatus of 1st Example of this invention. It is a figure which shows the frequency characteristic of the gain of a Z-axis direction when the distance from the short board in the antenna apparatus of 1st Example of this invention to the position fed with a feed element is made into a parameter. It is a perspective view which shows the structure of the antenna apparatus of 2nd Example of this invention. It is a top view which shows the structure of the antenna apparatus of 3rd Example of this invention. It is a figure which shows the structure of the control part in the antenna apparatus of 3rd Example of this invention. It is a figure which shows the structure of the conventional antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antenna apparatus, 2 Antenna apparatus, 3 Antenna apparatus, 10 Ground board, 11 Feed part, 11a Short board, 11b Feed element, 12 Coaxial cable, 13 Radiation element, 20 Ground board, 21 Feed part, 21a Short board, 21b Feed Element, 22 Feed line, 23 Radiation element, 24 Substrate, 30 Ground plate, 31-1 to 31-4 Feed part, 31a-1 to 31a-4 Short plate, 31b-1 to 31b-4 Feed element, 32-1 32-4 Feed line, 33-1-33-4 Radiating element, 34 Substrate, 35 Control unit, 36 Ground conductor, 37 Power supply, 102 Printed circuit board, 103 Dielectric substrate, 105 Ground electrode, 106 Radiator, 107 Conductor, 108 Waveguide electrode, 111 Housing, 200 Inverted F type antenna, 201 Inverted F type antenna, 210 Ground plate 211a short plates, 212 coaxial cable, 213 radiating element

Claims (4)

An earth plate,
A power feeding portion comprising: a short plate disposed on the ground plate and having one end connected to the ground plate; and a power feeding element extending substantially parallel to the ground plate at a right angle from the other end of the short plate; ,
Power supply means for supplying power to a predetermined position of the power supply element in the power supply unit;
A radiating element that covers the entire surface of the power feeding unit disposed substantially in parallel with a predetermined gap on the power feeding unit;
The frequency band extending from the low frequency f1 to the high frequency f2 is the use frequency band, and when the wavelength of the frequency f1 is λ1 and the wavelength of the frequency f2 is λ2, the length of the feeding element is about 0.13λ1. is the length of about 0.26Ramuda1, distance from the short plate to the predetermined position to be fed at the feed element is about 0.04λ2~ about 0.17λ2 distance, the head of the long sides of the radiation element The length of the antenna device is about 0.43λ2 to about 0.54λ2, and the ground plate is larger than the radiating element. A ground plate erected substantially perpendicular to one surface of the flat insulating substrate;
A power feeding unit comprising a short plate having one end connected to the ground plate, and a power feeding element extending substantially orthogonally from the other end of the short plate and disposed substantially parallel to the ground plate;
A feed line that is formed on the insulating substrate and feeds a predetermined position of the feed element in the feed unit;
A radiation element that is disposed substantially parallel to the power supply element with a predetermined gap so as to cover the entire surface of the power supply element, and is erected substantially orthogonally on the insulating substrate;
A frequency band extending from a low frequency f1 to a high frequency f2 is a use frequency band, and when the wavelength of the frequency f1 is λ1 and the wavelength of the frequency f2 is λ2, the length of the feeding element is about 0.18λ1. is the length of about 0.30Ramuda1, distance from the short plate to the predetermined position to be fed at the feed element is about 0.04λ2~ about 0.17λ2 distance, the head of the long sides of the radiation element The length of the antenna device is about 0.43λ2 to about 0.54λ2, and the ground plate is larger than the radiating element. A polygonal cylindrical earth plate standing substantially perpendicular to one surface of the flat insulating substrate;
A short plate having one end connected to each polygonal outer surface of the ground plate, and a feeding element extending substantially orthogonally from the other end of the short plate and disposed substantially parallel to the ground plate A plurality of power supply portions provided for each outer surface of the polygon in the ground plate,
A plurality of feed lines that are formed on the insulating substrate so as to feed power to predetermined positions of the feed elements, and are provided corresponding to polygonal outer surfaces of the ground plate;
Each of the feeding elements is arranged substantially in parallel with a predetermined gap so as to cover the entire surface of each of the feeding elements, and each polygonal outer surface of the ground plate stands substantially orthogonally on the insulating substrate. A plurality of radiating elements installed;
A control unit that is provided on the insulating substrate and selectively supplies power to the plurality of power supply lines ;
A frequency band extending from a low frequency f1 to a high frequency f2 is a use frequency band, and when the wavelength of the frequency f1 is λ1 and the wavelength of the frequency f2 is λ2, the length of the feeding element is about 0.18λ1. The distance from the short plate to the predetermined position fed by the feeding element is a distance of about 0.04λ2 to about 0.17λ2, and the long side of the radiating element Is about 0.43λ2 to about 0.54λ2, and the ground plate is larger than the radiating element .   The antenna device according to claim 2, wherein a ground conductor facing at least the feed line is formed on the other surface of the insulating substrate.

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