JP7529244B2 - Antenna Systems - Google Patents

Description

The present invention relates to an antenna system having multiple antennas.

It is necessary to know the direction of arrival of radio waves in order to locate interfering signal sources, grasp the location of a terminal, etc. One method for estimating the direction of arrival of radio waves is to check the phase difference between signals arriving at multiple antennas (see, for example, Patent Document 1).

For example, if there are two antennas and the received signals from those antennas have the same phase, then the radio waves are arriving from a direction perpendicular to the line connecting the two antennas. If there is a phase difference, there will be a difference in arrival time corresponding to that phase difference, and from that the direction of arrival can be estimated.

JP 2006-352296 A

For example, if the phase difference between two antennas is converted into a wavelength and the result is Δλ, and if the distance between the two antennas is d, the relationship between the incident angle θ with respect to the direction in which the antennas are aligned, Δλ, and d is expressed by the following formula.
sinθ=Δλ/d

Here, Δλ can be understood to be in the range of 0 or more and less than λ. For example, even if there is a phase difference equivalent to 1.5λ between two antennas, it will be recognized as 0.5λ. To prevent this from happening, the following condition must be satisfied for the distance (spacing) d between the antennas. Here, λ is the wavelength of the radio wave.
d<λ/2

If the antennas can be placed at this granularity, it will be possible to determine the direction of arrival from the phase difference. On the other hand, if the antenna spacing is narrowed, the phase difference between the signals received by each antenna will be smaller, making them more susceptible to noise and other factors. As a result, errors will be more likely to occur. Therefore, it is appropriate to place antennas at intervals close to λ/2.

When antennas are placed at intervals close to λ/2 like this, the antenna spacing will depend on the wavelength. Generally, antennas are attached to a fixture that holds them in place, so in order to satisfy the antenna spacing conditions, it is necessary to either fix the frequency being used or to reattach the antennas every time the frequency is changed.

The present invention has been made to solve the above problems, and aims to provide an antenna system that can handle various radio wave frequencies.

To achieve the above object, an antenna system according to one aspect of the present invention includes multiple antennas and a spacing change mechanism that can change the spacing between the multiple antennas.

This configuration allows the distance between multiple antennas to be changed, so that, for example, the distance between two antennas can be set to be shorter than λ/2 but close to λ/2.

In addition, in an antenna system according to one aspect of the present invention, the spacing change mechanism may be an extension mechanism that supports multiple antennas.

With this configuration, the spacing between multiple antennas can be changed by expanding or contracting the expansion mechanism.

In addition, in an antenna system according to one aspect of the present invention, the spacing change mechanism may have multiple support members connected to be rotatable around a rotation axis, and the multiple antennas may be supported by the multiple support members, respectively.

With this configuration, the spacing between the multiple antennas can be changed by rotating the multiple support members around the rotation axis.

In addition, in an antenna system according to one aspect of the present invention, the spacing change mechanism includes multiple telescopic mechanisms that expand and contract radially, and the multiple antennas are supported by the multiple telescopic mechanisms, and may be moved radially in response to the expansion and contraction of the multiple telescopic mechanisms.

With this configuration, for example, it becomes possible to change the radius of a circumference of multiple antennas that are positioned on a circumference when viewed from above. As a result, it becomes possible to have similar reception performance in various directions.

In addition, the antenna system according to one aspect of the present invention may further include a sensor capable of detecting at least one of the orientation, inclination, position, and distance between the multiple antennas.

With this configuration, for example, the direction of arrival of radio waves for multiple antennas and the orientation of the antenna system detected by a sensor can be used to determine the direction of arrival of radio waves. Also, for example, the tilt of multiple antennas detected by a sensor can be used to correct horizontal deviations of the antennas. Also, for example, the position of the antenna system detected by a sensor can be used to determine the location where the direction of arrival of radio waves was obtained. Also, for example, by detecting the distance between multiple antennas with a sensor, it becomes unnecessary to manually measure the distance between the antennas when installing the antennas.

An antenna system according to one aspect of the present invention makes it possible to change the spacing between antennas depending on the frequency of the radio waves.

FIG. 1 is a schematic diagram showing an example of a configuration of an antenna system according to an embodiment of the present invention; FIG. 2 is a schematic diagram showing another example of the configuration of the antenna system according to the embodiment; FIG. 2 is a schematic diagram showing another example of the configuration of the antenna system according to the embodiment; FIG. 2 is a schematic diagram showing another example of the configuration of the antenna system according to the embodiment; FIG. 2 is a schematic diagram showing another example of the configuration of the antenna system according to the embodiment;

The antenna system according to the present invention will be described below using an embodiment. Note that in the following embodiments, components with the same reference numerals are the same or equivalent, and repeated explanations may be omitted. The antenna system according to this embodiment has a spacing change mechanism that can change the spacing between multiple antennas.

Figure 1 is a schematic diagram showing the configuration of an antenna system 1 according to this embodiment. The antenna system 1 according to this embodiment includes multiple antennas 10-1, 10-2, and 10-3, and a spacing change mechanism 20. In addition, when the antennas 10-1, 10-2, and 10-3 are not particularly distinguished from each other, they may be called antennas 10. In Figure 1, the antenna system 1 has three antennas 10, but the number of antennas 10 that the antenna system 1 has may be two or more, and is not limited to this number. The antenna 10 may be, for example, a non-directional linear antenna such as a dipole antenna. The multiple antennas 10 may be arranged so that, for example, the longitudinal direction is vertical and the multiple antennas 10 are positioned in a straight line when viewed from above. In this case, the multiple antennas 10 may move in a straight line when viewed from above by changing the spacing between the antennas 10. In addition, the method of calculating the direction of arrival of radio waves using multiple antennas 10 arranged in a straight line as described above is already known, and a detailed description thereof will be omitted.

The interval change mechanism 20 can change the interval between the multiple antennas 10. The interval change mechanism 20 may be a platform that supports the multiple antennas 10. FIG. 1 shows the case where the interval change mechanism 20 is an extension mechanism that supports the multiple antennas 10, and is a telescopic pipe in particular. As shown in FIG. 1, the interval change mechanism 20, which is a telescopic pipe, may be a telescopic pipe in which multiple pipe-shaped members 21 to 23 with different inner diameters are connected to each other and can be extended and retracted. More specifically, the pipe-shaped member 22 can be inserted into the pipe-shaped member 21, and the pipe-shaped member 23 can be inserted into the pipe-shaped member 22. The pipe-shaped members 21 to 23 support the antennas 10-1 to 10-3, respectively. The interval between the multiple antennas 10 can be changed by changing the degree of insertion of the pipe-shaped members 22 and 23 in the direction of the double arrow. In this embodiment, the case where the lower end side of the antenna 10 is supported by the interval change mechanism 20 will be mainly described, but it goes without saying that other parts of the antenna 10 may be supported.

The ends of the pipe-shaped members 21 to 23 on the side where no other pipe-shaped members are inserted may be open or closed. For example, in FIG. 1, the left ends of the pipe-shaped members 21 to 23 and the right end of the pipe-shaped member 23 may be closed.

Note that FIG. 1 shows a case where the cross-sectional shape perpendicular to the longitudinal direction of the pipe-shaped members 21 to 23 is rectangular, but the cross-sectional shape may be, for example, circular, polygonal, semicircular, etc.

In addition, the material constituting the spacing change mechanism 20 is not particularly limited, but depending on the structure of the antenna 10 and the location of use, for example, a non-conductive material (e.g., resin, wood, ceramic, etc.) may be preferable, or a conductive material (e.g., metal, etc.) may be acceptable or preferable.

The spacing change mechanism 20 may have, for example, the same number of pipe-shaped members as the number of antennas 10, or may have a greater number of pipe-shaped members. The surfaces of the pipe-shaped members may also be marked with scales 24 for reading the distance between the antennas 10. For example, the scale 24 on the pipe-shaped member 22 may indicate the distance between antennas 10-1 and 10-2. For example, the scale 24 on the pipe-shaped member 23 may indicate the distance between antennas 10-2 and 10-3.

The configuration of the spacing change mechanism 20 shown in FIG. 1 is one example, and the spacing change mechanism 20 may be capable of changing the spacing between the multiple antennas 10 by other telescopic mechanisms. For example, as shown in FIG. 2, the spacing change mechanism 20 may be a telescopic link mechanism. FIG. 2 is a plan view of the antenna system 1 showing the antenna 10 in a see-through state. The telescopic link mechanism may be a magic hand type having multiple link members 26 rotatably connected by a pivot 25. The multiple antennas 10 may be provided approximately in the center of the longitudinal direction of the link member 26. In this case, the spacing between the antennas 10 can be changed by telescopically extending the telescopic link mechanism in the direction of the double arrow in FIG. 2.

As described above, according to the antenna system 1 of this embodiment, the spacing between the multiple antennas 10 can be changed by the spacing change mechanism 20, which is an extension mechanism, and the spacing between the antennas 10 can be easily changed to a spacing suitable for identifying the direction of arrival of radio waves. Note that in order to achieve the same thing, it is possible to arrange many antennas at close intervals in advance and receive radio waves using only antennas spaced according to the frequency (wavelength) of the radio waves to be received. However, in that case, the presence of antennas not used for reception will disrupt the radio waves, making it impossible to accurately identify the direction of arrival of the radio waves. For this reason, it is preferable to change the spacing between the antennas 10, as in the antenna system 1 of this embodiment.

Next, we will explain a modified example of the antenna system 1 according to this embodiment.

[Gap change mechanism having multiple support members rotatably connected]
As shown in FIG. 3, the interval change mechanism 20 has a plurality of support members 31 to 33 connected to be rotatable about a rotation shaft 30, and the antennas 10 may be supported by the plurality of support members 31 to 33. The support members 31 to 33 may be rod-shaped members, for example, as shown in FIG. 3. The antennas 10 may be provided at the end of each of the support members 31 to 33 opposite to the rotation shaft 30. With this configuration, the interval between the antennas 10 can be changed by changing the angle between the support members 31 to 33. For example, the interval between the antennas 10 can be changed by changing the position of the plurality of antennas 10 in the direction of the double arrow in FIG. 3. The plurality of antennas 10 may be provided, for example, such that the longitudinal direction is vertical and the antennas 10 are positioned on an arc in a top view. In this case, the plurality of antennas 10 may move on an arc in a top view by changing the interval between the antennas 10. Note that a method for calculating the direction of arrival of radio waves using a plurality of antennas 10 arranged on an arc is already known, and a detailed description thereof will be omitted.

In order to make each of the support members 31 to 33 parallel to the installation surface (e.g., the floor or the ground) of the antenna system 1, a cylindrical member 41 may be provided on the underside of the end of the support members 32 and 33 opposite the pivot axis 30. The cylindrical member 41 may be considered to be a spacer that maintains a distance between the end of the support members 32 and 33 on which it is provided and the installation surface.

In addition, in order to align the height of the lower end of each antenna 10, a cylindrical member 42 may be provided on the upper surface side of the end opposite the pivot shaft 30 of the support members 31 and 32. The cylindrical member 42 may be considered to be a platform member on which the antenna 10 is mounted.

The cylindrical members 41, 42 may have other shapes as long as the above-mentioned objectives can be achieved. In addition, in cases where the support members 31 to 33 do not need to be parallel to the installation surface, or where the height of the lower end of the antenna 10 does not need to be uniform, the cylindrical members 41, 42 do not need to be provided at the ends of the support members 31 to 33 opposite the pivot shaft 30.

In addition, a scale that allows the angle between the support members 31 to 33 to be read may be displayed on the end of the support members 31 to 33 on the side of the rotation axis 30. In this way, the distance between the antennas 10 can be determined using the read angle.

In addition, while FIG. 3 shows rod-shaped support members 31 to 33 arranged in a fan shape, support members 31 to 33 may be shaped other than rod-shaped.

Although FIG. 3 shows a case where the number of antennas 10 is three, it goes without saying that other numbers are also possible. Also, in FIG. 3, the support members 31 to 33 may each be extendable. The extendable support members may be, for example, telescopic pipes.

[Spacing change mechanism having multiple expansion and contraction mechanisms that expand and contract radially]
As shown in Fig. 4, the interval change mechanism 20 may include a plurality of telescopic mechanisms 51 to 56 that extend and retract radially. The plurality of telescopic mechanisms 51 to 56 may each include a main body portion 51-1 to 56-1 and a tip portion 51-2 to 56-2, and the tip portion 51-2 to 56-2 may be inserted into the main body portion 51-1 to 56-1, respectively, and may extend and retract in the direction indicated by the double arrow by changing the degree of insertion. In this case, the telescopic mechanisms 51 to 56 are each formed of a telescopic pipe. Note that Fig. 4 shows a case in which the telescopic mechanisms 51 to 56 are formed by connecting two pipes having different inner diameters, but it goes without saying that three or more pipes having different inner diameters may be connected.

In addition, FIG. 4 shows a case where the telescopic mechanisms 51 to 56 are arranged so that the telescopic directions are isotropic when viewed from above, that is, the angles between the straight lines along the telescopic directions of the telescopic mechanisms 51 to 56 are equal, but this is not necessarily the case. It goes without saying that the telescopic mechanisms 51 to 56 may be other than telescopic pipes. In addition, FIG. 4 shows a case where the interval change mechanism 20 has six telescopic mechanisms 51 to 56, but the number of telescopic mechanisms that the interval change mechanism 20 has may be three or more, and the number is not important. In addition, FIG. 4 shows a case where the center side of the telescopic mechanisms 51 to 56, that is, the base end side of the main body parts 51-1 to 56-1, is fixed, but this is not necessarily the case. For example, the center side of the telescopic mechanisms 51 to 56 may be connected to be rotatable around a rotation axis.

The multiple antennas 10-1 to 10-6 are supported by multiple telescopic mechanisms 51 to 56, respectively. More specifically, the multiple antennas 10-1 to 10-6 are supported by multiple tip portions 51-2 to 56-2, respectively. Therefore, the multiple antennas 10-1 to 10-6 are moved radially in response to the telescopic mechanisms 51 to 56 being telescopic. Therefore, for example, the multiple antennas 10 can be arranged in a circular shape when viewed from above. The radius of the circular shape can be changed by telescopic mechanisms 51 to 56 being telescopic. By arranging the antennas 10 in this way, it is possible to have similar reception performance in various directions. For example, when the multiple antennas 10 are arranged in a straight line, the detection accuracy of the direction of arrival is high for radio waves arriving from a direction close to perpendicular to the straight line. However, the detection accuracy of the direction of arrival is low for radio waves arriving from a direction close to the straight line. On the other hand, as shown in Figure 4, when the antennas 10 are arranged in a circle, the antennas 10 are arranged nearly perpendicular to the direction of arrival of the radio waves, so the direction of arrival can be detected with similar accuracy for any direction. Also, when multiple antennas 10 are arranged in a circle, it is possible to identify not only the direction of arrival of the radio waves (e.g., east-west direction), but also the side of the wave source (e.g., west side, east side, etc.).

[Sensor]
5, the antenna system 1 may further include a sensor 50. The sensor 50 may be capable of detecting, for example, at least one of the orientation, tilt, position, and distance between the multiple antennas 10. The sensor 50 is typically attached to the interval changing mechanism 20.

The sensor 50 that detects the direction may be, for example, a geomagnetic sensor or a direction sensor. In this case, for example, it is possible to determine an absolute angle indicating the direction of arrival of the radio waves (for example, an azimuth angle with north being 0 degrees) by using a relative angle that is the direction of arrival of the radio waves with respect to the antenna system 1 determined using multiple antennas 10 and an absolute angle of the antenna system 1 acquired by the sensor 50.

The sensor 50 that detects the tilt may be, for example, a tilt sensor. In this case, for example, it may be possible to correct the deviation of the antenna 10 from the horizontal using the detected tilt angle of the antenna system 1.

The sensor 50 that detects the position may be, for example, a GPS (Global Positioning System) sensor. In this case, for example, it becomes possible to acquire a position that specifies the direction from which the radio waves are coming. In addition, the sensor 50, which is a GPS sensor, may be used to record the time at which the radio waves are received in order to specify the direction from which the radio waves are coming.

The sensor 50 that detects the distance between the multiple antennas 10 may be, for example, a distance measurement sensor. The distance measurement sensor may be, for example, a laser sensor such as a laser range sensor (laser range scanner), an ultrasonic sensor, a distance sensor using microwaves, or the like. In this case, for example, by using the detected distance between the antennas 10, it becomes unnecessary to measure the distance between the antennas 10 manually. For example, the multiple antennas 10 may be arranged so that the interval between the multiple antennas 10 is less than half the wavelength of the radio waves to be received by eye, which improves the workability when arranging the antennas 10.

When two or more detections are performed by the sensor 50, the sensor 50 may be a collection of two or more sensors. For example, when the sensor 50 detects the azimuth and tilt, the sensor 50 may have a geomagnetic sensor and a tilt sensor. Also, while FIG. 5 shows a case where the sensor 50 is provided in the antenna system 1 shown in FIG. 4, this is not essential. The sensor 50 may be provided in any of the antenna systems 1 shown in FIGS. 1 to 3, or in other antenna systems 1.

[Transmitting antenna]
In this embodiment, the case where multiple antennas 10 are used as receiving antennas has been mainly described. However, due to the symmetry of radio waves, it goes without saying that the present invention can also be applied to the case where multiple antennas 10 are used as transmitting antennas or transmitting/receiving antennas.

Furthermore, the present invention is not limited to the above-described embodiment, and various modifications are possible, and it goes without saying that these are also included within the scope of the present invention.

As described above, the antenna system according to one aspect of the present invention has the advantage that the spacing between multiple antennas can be easily changed according to the frequency of the radio waves, making it useful, for example, as an antenna system used to obtain the direction of arrival of radio waves.

1 Antenna system 10, 10-1 to 10-6 Antenna 20 Spacing change mechanism 31 to 33 Support member 50 Sensor 51 to 56 Extension mechanism

Claims (2)

A plurality of antennas;
a spacing change mechanism capable of changing the spacing between the plurality of antennas ,
the distance changing mechanism is a telescopic link mechanism in the form of a hook-like hand in which a plurality of link-like members are connected,
An antenna system , wherein the multiple antennas are each supported at a position where the link-like members of the telescopic link mechanism intersect . The antenna system of claim 1 , further comprising a sensor capable of detecting at least one of an orientation, a tilt, a position, and a distance between said plurality of antennas.

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