JP6456506B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device characterized by a small and wide-band circularly polarized radiation.

  Terminals used in satellite telephone services and location information services using global positioning system (GPS) satellites use circularly polarized radiation antennas that are less prone to polarization loss in order to respond flexibly to user movements. ing.

  Examples of antenna systems characterized by circular polarization include spiral antennas and patch antennas. However, since these antennas are large, miniaturization is required.

  In addition, in order to share a plurality of systems with a single antenna or to make it more multifunctional, it is also required to increase the bandwidth to use a plurality of frequency bands.

  On the other hand, Patent Document 1 discloses circularly polarized waves that can be reduced in size and thickness by exciting four L-shaped excitation probes with a phase difference of 90 degrees in the circumferential direction with respect to the cavity center. An antenna device capable of radiation is shown.

  Patent Document 2 discloses a small and wideband antenna device that can easily adjust the resonance frequency by combining an inverted F antenna and an inverted L antenna.

JP2011-3984A JP 2003-124742 A

  However, Patent Document 1 discloses an antenna device capable of small circularly polarized radiation, but does not describe any means for increasing the bandwidth.

  Patent Document 2 discloses a small and wide-band antenna device, but does not describe a means for radiating circularly polarized waves.

  In view of the above, an object of the present invention is to provide an antenna device that enables small and wide-band circularly polarized radiation.

The antenna device according to the present invention extends from the ground conductor to the ground conductor, vertically from one end to the other end, bends approximately 90 degrees so as to be horizontal with the ground conductor at a predetermined location, and has a length of the used frequency. 90 degrees so that the first conductor, which is approximately ¼ wavelength, and one end connected to the ground conductor extend vertically from the ground conductor and is horizontal with the ground conductor at a predetermined location. Four partial antennas having a second conductor disposed between the ground conductor and the first conductor so that the other end is bent and the other end faces the same direction as the other end of the first conductor, An antenna radiating section which is arranged in a shape overlapping each side of the square when viewed from the direction, and is excited by an oscillation circuit with a 90-degree phase difference between the ends of the first conductors of adjacent partial antennas , The second conductor is disposed at a position where the second conductor is electromagnetically coupled to the first conductor; The length of the conductor, in which as is different from the length of the first conductor.

  According to the present invention, it is possible to provide a small and broadband antenna device that radiates circularly polarized waves.

The block diagram which shows the antenna apparatus in Embodiment 1 of this invention. The block diagram which shows the partial antenna in Embodiment 1 of this invention. The block diagram which looked at the antenna apparatus in Embodiment 1 of this invention from the sky over a ground conductor. The block diagram which shows the antenna apparatus in Embodiment 2 of this invention. The block diagram which shows the partial antenna in Embodiment 2 of this invention. The figure which shows the electrical property of the antenna apparatus in Embodiment 2 of this invention. The figure which shows the radiation pattern of the antenna apparatus in Embodiment 2 of this invention. The block diagram which shows the antenna apparatus in Embodiment 3 of this invention. The block diagram which shows the partial antenna in Embodiment 3 of this invention. The block diagram which shows the antenna apparatus in Embodiment 4 of this invention. The figure which shows the electrical property of the antenna apparatus in Embodiment 4 of this invention. The figure which shows the radiation pattern of the antenna apparatus in Embodiment 4 of this invention. The block diagram which shows the antenna apparatus in Embodiment 5 of this invention. The figure which shows the electrical property of the antenna apparatus in Embodiment 5 of this invention. The block diagram which shows the antenna apparatus in Embodiment 6 of this invention. The figure which shows the radiation pattern of the antenna apparatus in Embodiment 6 of this invention.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing an antenna apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, 1 is a first partial antenna, 2 is a second partial antenna, 3 is a third partial antenna, 4 is a fourth partial antenna, and 5 is a ground conductor.

The first partial antenna 1, the second partial antenna 2, the third partial antenna 3, and the fourth partial antenna 4 have the same structure, and the first partial antenna 1 will be described with reference to FIG.
The first partial antenna 1, the second partial antenna 2, the third partial antenna 3, and the fourth partial antenna 4 are collectively referred to as an antenna radiating unit.

  In FIG. 2, 5 is a ground conductor, 101 is a first conductor, 102 is a second conductor, and 103 is a feeding point.

  One end of the first conductor 101 extends vertically from the ground conductor 5, and includes a portion perpendicular to the ground conductor 5 and a horizontal portion. In the example of FIG. 2, the case where the first conductor 101 forms an inverted L-shaped antenna is shown.

  The second conductor 102 is disposed between the first conductor 101 and the ground conductor 5, and is configured by a portion parallel to a portion perpendicular to the ground conductor 5. The second conductor 102 is arranged such that one end of a portion perpendicular to the ground conductor 5 is short-circuited to the ground conductor 5 and one end of a portion parallel to the ground conductor 5 is oriented in the same direction as the first conductor 101. It is an element.

  Note that FIG. 2 shows a case where the second conductor 102 forms an inverted L-shaped antenna.

  A feeding point 103 indicates a position to which a high-frequency voltage that is a source of electromagnetic waves radiated from the antenna device is applied. In FIG. 2, the feeding point 103 is schematically drawn, but the feeding point 103 is not formed as a physical component in mounting.

  As shown in FIG. 1, the partial antennas 1 to 4 are arranged so as to be 90-degree rotationally symmetric. When the antenna element in the present embodiment is viewed from above the ground conductor 5, as shown in FIG. 3, the open ends of the first conductors 101 of the partial antennas 1 to 4 are square counterclockwise, respectively. It is arranged to be on one side.

Furthermore, in this embodiment, it is assumed that a distribution circuit (not shown) for exciting each feeding point 103 with a phase difference of 90 degrees with the same amplitude is provided. In the present embodiment, this distribution circuit gives a +90 degree phase difference in the clockwise direction when viewed from above the ground conductor 5.
The distribution circuit may be formed by etching a copper foil pattern using a new dielectric substrate for a circuit.

  Next, the operation will be described.

  The distribution circuit outputs a high-frequency voltage (signal) to the feeding point 103 of each partial antenna. The signals output to the feed points 103 of the partial antennas have a phase difference of 90 degrees. For example, the feed point 103 of the partial antenna 1 is 0 degrees and the feed point 103 of the partial antenna 2 is A signal with a phase difference of 90 degrees, 180 degrees at the feed point 103 of the partial antenna 3 and 270 degrees at the feed point 103 of the partial antenna 4 is output.

The operation within each partial antenna will be described.
A signal input to the antenna element composed of the first conductor 101 is radiated to the space due to a resonance phenomenon when traveling on the line. At that time, the antenna element consisting of the first conductor 101 causes the electromagnetic field coupling to occur by arranging the antenna element consisting of the second conductor 102 at a position where the electric field is strengthened, and the current on the line of the second conductor 102 is generated. Flows.

  The total length of the antenna element made of the first conductor 101 and the antenna element made of the second conductor corresponds to the resonance frequency. The total length of the antenna element made of the first conductor 101 and the antenna element made of the second conductor 102 is about ¼ wavelength of the respective resonance frequency.

  Therefore, by making the total length of the antenna element made of the first conductor 101 and the antenna element made of the second conductor 102 have different values, the resonance frequency of the antenna element made of the first conductor 101, The resonance frequency of the antenna element formed of the second conductor 102 can be shifted.

  Since a signal having the same amplitude but a phase difference of 90 degrees is input to the feed point 103 of each partial antenna, a phase difference of 90 degrees is also generated in the current flowing on the antenna element, resulting in a circular polarization. Wave radiation is possible.

  As described above, the total length of the antenna element made of the first conductor 101 and the antenna element made of the second conductor 102 are set to different values, the resonance frequency of the antenna element made of the first conductor 101, the second By arranging the partial antennas having the resonance frequency of the antenna element made of the conductor 102 so as to be 90-degree rotationally symmetric, it is possible to increase the frequency and widen the frequency band.

In the case of the configuration of FIG. 1 used in the present embodiment, the reverse L antenna made of the first conductor 101 has a longer overall length than the reverse L antenna made of the second conductor 102, so that the resonance frequency is the second. It becomes lower than the inverted L antenna composed of the conductor 102.
Embodiment 2. FIG.
In the first embodiment, one end of the ground conductor 5 is short-circuited, and the first conductor 101 composed of a portion parallel to the portion perpendicular to the ground conductor 5 and one end of the portion perpendicular to the ground conductor 5 are connected to the ground conductor 5. The total length of the second conductor 102 disposed between the first conductor 101 and the ground conductor 5 is different so that one end of the portion parallel to the ground conductor 5 is short-circuited and faces the same direction as the first conductor 101. A case has been described in which the partial antennas 1 to 4 are arranged so as to be 90-degree rotationally symmetric so that the antenna device that radiates circularly polarized waves has a multi-frequency and a wide band.

  In the present embodiment, the impedance matching when adjusting the resonance frequency between the antenna element consisting of the first conductor 101 and the antenna element consisting of the second conductor 102 for each partial antenna is facilitated. explain.

  FIG. 4 is a block diagram showing an antenna device according to the embodiment of the present invention. As in Embodiment 1, in FIG. 4, the first partial antenna 1, the second partial antenna 2, the third partial antenna 3 and the fourth partial antenna 4 have the same structure, and FIG. The first partial antenna 1 according to the present embodiment will be described as a representative example. 5, the same reference numerals as those in FIG. 2 denote the same or corresponding parts.

  The antenna device according to the present embodiment has the same basic configuration as that of the first embodiment, except that each partial antenna has a third conductor 104.

  As shown in FIG. 5, one end of the third conductor 104 is short-circuited to the ground conductor 5, and the third conductor 104 is composed of a portion parallel to the portion perpendicular to the ground conductor 5, and the other end is connected to the first conductor 101. .

FIG. 5 shows a case where the first conductor 101 and the third conductor 104 form an inverted F-shaped antenna.
As in the first embodiment, in this embodiment, the partial antennas 1 to 4 are arranged so as to be 90-degree rotationally symmetric.
As in the first embodiment, in this embodiment, it is assumed that a distribution circuit for exciting each feeding point 103 with a phase difference of 90 degrees with the same amplitude is provided.

Next, the operation will be described.
The distribution circuit outputs a high-frequency voltage (signal) to the feeding point 103 of each partial antenna. The signals output to the feed points 103 of the partial antennas have a phase difference of 90 degrees. For example, the feed point 103 of the partial antenna 1 is 0 degrees and the feed point 103 of the partial antenna 2 is A signal with a phase difference of 90 degrees, 180 degrees at the feed point 103 of the partial antenna 3 and 270 degrees at the feed point 103 of the partial antenna 4 is output.
For example, by applying a sine wave voltage source to the feeding point 103, a high frequency voltage (signal) is input to the antenna element formed of the first conductor 101.

The operation within each partial antenna will be described.
A signal input to the antenna element composed of the first conductor 101 is radiated to the space due to a resonance phenomenon when traveling on the line. At that time, the antenna element consisting of the first conductor 101 causes the electromagnetic field coupling to occur by arranging the antenna element consisting of the second conductor 102 at a position where the electric field is strengthened, and the current on the line of the second conductor 102 is generated. Flows.

At this time, the third conductor 104 substitutes for a capacitor or a coil that performs impedance matching of the first conductor 101 due to the effect of a short stub whose tip is short-circuited.
For example, when the original characteristic impedance is Zs, the characteristic impedance when the short stub is added is Z, the stub length is l, and the wave number is β = 2π / λ, the short stub is generally expressed by the following equation.
Z = j * Zs * tan (βl)
Therefore, if l <λ / 4, it operates as a parallel inductor, and if λ / 4 <l <λ / 2, it operates as a parallel capacitor. Therefore, the impedance can be adjusted by adjusting the size of the short stub. is there.

FIG. 6 is a diagram showing the electrical characteristics of the antenna device according to the present embodiment. The horizontal axis in FIG. 6 is the normalized frequency, and the vertical axis is the reflection characteristic S11.
As can be seen from FIG. 6, it can be seen that resonance occurs in the vicinity of 0.86f0 and 1.1f0, and two frequencies are obtained. Furthermore, it can be said that the reflection characteristic S11 is -10 dB or less, which is a good characteristic.

FIG. 7 is a diagram showing a radiation pattern of the antenna device according to the present embodiment. The horizontal axis in FIG. 7 is the elevation angle, the vertical axis is the directivity gain, the RHCP (right-handed circularly polarized wave) that is the main polarization component is indicated by a solid line, and the LHCP (left-handed circular polarized) that is the cross-polarization component wave) is indicated by a broken line.
As can be seen from FIG. 7, RHCP is the peak gain at θ = 0 deg, which is the zenith angle, and LHCP is −40 dBi or less at the above angle, and a circular polarization characteristic with a good axial ratio is obtained.

  As described above, the resonance frequency of the antenna element composed of the first conductor 101 is adjusted by changing the size and thickness of the third conductor 104 having the third conductor 104 of each partial antenna. Is possible.

Embodiment 3 FIG.
In the present embodiment, a case will be described in which an antenna element made of the first conductor 101 and an antenna element made of the second conductor 102 are formed as a pattern on a dielectric substrate for each partial antenna.

  FIG. 8 is a configuration diagram showing the antenna device according to the present embodiment. As in the second embodiment, in FIG. 8, the first partial antenna 1, the second partial antenna 2, the third partial antenna 3 and the fourth partial antenna 4 have the same structure, and FIG. 9 is used. The first partial antenna 1 according to the present embodiment will be described as a representative example. 9, the same reference numerals as those in FIG. 5 denote the same or corresponding parts.

  The antenna device according to the present embodiment has the same basic configuration as that of the second embodiment, except that each partial antenna has a dielectric substrate 105.

  One side of the dielectric substrate 105 is short-circuited to the ground conductor 5, and the first conductor 101, the second conductor 102, the feeding point 103, and the third conductor 104 are disposed on one surface that is perpendicular to the ground conductor 5. It is formed as a distributed constant element such as a distributed constant inductance realized by a pattern or a transmission line. In the present embodiment, a glass epoxy substrate such as Frame Regentant Type 4 (FR4) is assumed as the dielectric substrate 105, but a substrate using ceramic, alumina oxide, or the like as long as the dielectric constant is high and the material is stable. But you can.

  The feeding point 103 does not need to be formed on the pattern of the dielectric substrate 105, and a ground point between the pattern of the dielectric substrate 105 and the dielectric 100 may be used.

  The size of the distributed constant circuit formed as a pattern on the dielectric substrate 105 can be reduced by a shortening rate expressed by the dielectric constant of the substrate.

As described above, the antenna device is made smaller by forming the antenna element made of the first conductor 101, the antenna element made of the second conductor 102, and the third conductor 104 as the pattern on the dielectric substrate 105. Is possible.
Embodiment 4 FIG.
In the first to third embodiments, a description will be given of a case where the open ends of the first conductors 101 of the partial antennas 1 to 4 are arranged counterclockwise so as to be one side of the square when viewed from above the ground conductor 5. did.
In the present embodiment, a case will be described in which the tips of the first conductors 101 of the partial antennas 1 to 4 are arranged clockwise so as to be one side of the square when viewed from above the ground conductor 5.

FIG. 10 is a block diagram showing an antenna device according to the present embodiment. As in the second embodiment, in FIG. 10, the first partial antenna 1, the second partial antenna 2, the third partial antenna 3 and the fourth partial antenna 4 have the same structure.
The basic configuration of the present embodiment is the same as that of the second embodiment, and the antenna element including the first conductor 101 and the third conductor 104 and the antenna element including the second conductor 102 are connected to the ground conductor 5. The difference is that the tip of the first conductor 101 faces in the clockwise direction when viewed from above the ground conductor 5 when arranged so as to be rotationally symmetric 90 degrees upward.
As for the distribution circuit, a phase difference of +90 degrees is given in the clockwise direction when viewed from above the ground conductor 5 as in the second embodiment.

  FIG. 11 is a diagram illustrating electrical characteristics of the antenna device according to the present embodiment, and FIG. 12 is a diagram illustrating a radiation pattern of the antenna device according to the present embodiment.

When the electrical characteristics of the antenna device of the present embodiment (FIG. 11) and the electrical characteristics of the antenna device of the second embodiment (FIG. 6) are compared, there is no significant change in the impedance characteristics, but the antenna of the present embodiment When the radiation pattern of the device (FIG. 12) and the radiation pattern of the antenna device of the second embodiment (FIG. 7) are compared, a circle with good axial ratio in which RHCP is maximized in the direction of zenith angle 0 degree (90 degrees of elevation). It can be seen that polarized waves are radiated. In addition, it can be seen that the antenna device of the present embodiment radiates RHCP more strongly in the direction of 0 ° zenith angle, and the gain of RHCP is higher.
This is because the current flowing through the antenna element tends to radiate right-handed circularly polarized waves on the same operating principle as that of a four-wire helical antenna.

As described above, when the tip of the first conductor 101 of the partial antennas 1 to 4 is arranged in a clockwise direction when viewed from above the ground conductor 5, each RHCP is in the apex direction. Maximum.
Embodiment 5. FIG.
In the first to fifth embodiments, the case where the widths of the antenna elements including the first conductors 101 related to the partial antennas are uniform has been described.
In the present embodiment, a case will be described in which the width of the antenna element made of the first conductor 101 relating to each partial antenna is changed.

FIG. 13 is a configuration diagram showing a partial antenna of the antenna device according to the present embodiment. 13, the same reference numerals as those in FIG. 5 denote the same or corresponding parts.
The antenna device according to the present embodiment has the same basic configuration as that of the second embodiment, but differs in that the width of the tip of the first conductor 101 of each partial antenna is narrow.
As shown in FIG. 13, the first conductor 101 in the present embodiment gradually changes from the connecting portion with the third conductor 104 to the tip thereof.
Note that in this embodiment, the dimensions and position of the antenna element formed of the second conductor 102 are not changed as compared with the second embodiment.
By gradually narrowing the tip of the first conductor 101, a portion through which a current flows is added to a portion through which a current flows as usual, so that a plurality of routes are generated, and a wide band can be realized.

  FIG. 14 is a diagram showing electrical characteristics when the configuration of the present embodiment is used. Comparing the case where the width of the first conductor 101 is narrowed toward the tip (FIG. 14) and the case where the width of the first conductor 101 is equal (FIG. 11), the low frequency band is changed to a wide band. I understand.

As described above, it is possible to widen the low frequency band by changing the width of the antenna element including the first conductor 101 related to each partial antenna.
Embodiment 6 FIG.
In the present embodiment, a description will be given of a case where the partial antennas 1 to 4 are arranged so as to have a gear shape when arranged so as to be 90-degree rotationally symmetric.

FIG. 10 is a block diagram showing an antenna device according to the present embodiment.
As in the second embodiment, the antenna device according to the present embodiment arranges the partial antennas 1 to 4 on the ground conductor 5 so as to be rotationally symmetric by 90 degrees, but the partial antennas 1 to 1 are viewed from above the ground conductor 5. The tip of 4 protrudes and it has the structure arrange | positioned so that it may become a gear shape.

  FIG. 16 is a diagram showing the electrical characteristics of the antenna device according to the present embodiment.

The main polarization component RHCP is indicated by a solid line, and the cross polarization component LHCP is indicated by a broken line. It can be seen that by configuring the partial antennas 1 to 4 as shown in FIG. 15, LHCP can be greatly reduced as compared with the radiation pattern diagram 12 in the fourth embodiment.
By adopting this configuration, the range where the electric field is strengthened can be arranged near the center of the ground conductor 5, so that it is possible to suppress the radiation to the rear of the ground conductor 5.

As described above, when the partial antennas 1 to 4 are arranged on the ground conductor 5 so as to be 90-degree rotationally symmetric, LHCP can be greatly reduced by being configured to have a gear shape. Therefore, it becomes difficult to be affected by multipath, and signals from satellites can be received without error.
That is, when this antenna device is used for a terminal or the like used in the location information service, it is possible to improve positioning accuracy.

  DESCRIPTION OF SYMBOLS 1 1st partial antenna, 2nd 2nd partial antenna, 3rd 3rd partial antenna, 4th 4th partial antenna, 5 Ground conductor, 101 1st conductor, 102 2nd conductor, 103 Feeding point, 104th 3 conductors, 105 dielectric substrate.

Claims (7)

With ground conductors,
From one end to the other end, it extends vertically from the ground conductor, bends approximately 90 degrees so as to be horizontal with the ground conductor at a predetermined location, and has a length that is approximately ¼ wavelength of the operating frequency. From the one end connected to the conductor and the ground conductor to the other end, the conductor extends vertically from the ground conductor, bends approximately 90 degrees so as to be horizontal with the ground conductor at a predetermined location, and the other end is Four partial antennas having the second conductor disposed between the ground conductor and the first conductor so as to face the same direction as the other end of the first conductor are viewed from the vertical direction of the ground conductor. Each of which is arranged in a shape that overlaps each side of the square, and an antenna radiating portion that is excited by an oscillation circuit with a 90-degree phase difference between one end of the first conductors of adjacent partial antennas ,
The second conductor is disposed at a position where the second conductor is electromagnetically coupled to the first conductor, and a length of the second conductor is different from a length of the first conductor. Antenna device.   The at least one of the partial antennas has a dielectric substrate that has one side in contact with the ground conductor and forms the first conductor and the second conductor on a surface thereof. Antenna device.   At least one of the partial antennas extends from the ground conductor vertically from one end to the other end connected to the ground conductor, bends approximately 90 degrees so as to be horizontal with the ground conductor at a predetermined location, and the like. The antenna device according to claim 1, further comprising a third conductor having an end facing the same direction as the other end of the first conductor and connected to a bent portion of the first conductor.   At least one of the partial antennas includes a dielectric substrate having one side in contact with the ground conductor and forming the first conductor, the second conductor, and the third conductor on a surface. The antenna device according to claim 3.   The four partial antennas are excited with the other end of the first conductor facing in the clockwise direction when viewed from above the ground conductor, and the oscillation circuit is excited with a phase difference of 90 degrees clockwise when viewed from above the ground conductor. The antenna device according to any one of claims 1 to 4, wherein:   6. The antenna device according to claim 3, wherein a thickness of the first conductor gradually decreases from the bent portion to the other end. 6.   The other end of at least one of the first conductors of the partial antenna is disposed so as to protrude outside the square when viewed from the vertical direction of the ground conductor. The antenna device according to one item.

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