JP6847066B2 - Antenna calibration method - Google Patents

Description

The present invention relates to an antenna calibration method applied to an antenna device including a plurality of antenna elements and a reflector that reflects electromagnetic waves.

Among the antenna devices, there is a type that adopts an array feeding method and forms an antenna beam by reflecting electromagnetic waves radiated by each antenna element group by a reflector. In such an antenna device, in order to obtain a desired radiation characteristic, calibration is performed to compensate for the difference in amplitude and phase characteristics between the antenna elements including the feeding circuit.

As a method used for this calibration, there is an element electric field vector rotation method (see, for example, Non-Patent Document 1). In the element electric field vector rotation method, a pickup antenna that receives an electromagnetic wave radiated from an antenna element is arranged in a distant region of a phased array antenna which is a plurality of antenna elements. Next, in the phased array antenna, an electromagnetic wave in a state where the phase of the transfer device of each antenna element is rotated is radiated, and the electromagnetic wave is received by the pickup antenna. This is repeated for all antenna elements, and the phase for calibrating each antenna element is calculated based on the received electromagnetic wave.

Mano, Katagi, "Element Amplitude Phase Measurement Method for Phased Array Antenna-Element Electric Field Vector Rotation Method-", IEICE Journal of Electronics, Information and Communication Engineers, 1982

In the case of an antenna device equipped with a phased array antenna, the radiable multi-beams illuminate different areas. Therefore, the antenna beam, that is, the antenna element capable of receiving the electromagnetic wave with the pickup antenna at a single place is limited. Antenna elements that cannot receive electromagnetic waves cannot be calibrated.

By arranging the pickup antenna for each antenna beam formed, it is possible to calibrate all the antenna elements. However, as the number of places where the pickup antennas are arranged increases, the cost required for calibrating all the antenna elements increases. Therefore, it is important to be able to calibrate all antenna elements while keeping costs down.

The present invention has been made to solve such a problem, and an object of the present invention is to provide an antenna calibration method capable of performing calibration for compensating for a difference in phase characteristics between antenna elements while suppressing costs. There is.

The antenna calibration method according to the present invention is an antenna provided with a plurality of antenna elements, a reflector used for at least one of reflection of electromagnetic waves radiated from each antenna element and reflection of electromagnetic waves to each antenna element. Assuming that it is applied to a device, it is assumed that two or more antenna elements targeting the same area among multiple antenna elements, and electromagnetic waves are generated in an overlapping area where the two or more areas overlap. By determining the observation point to be used for reception and at least one of the emission of the electromagnetic wave, and receiving the electromagnetic wave at each of the determined observation points, and performing at least one of the emission of the electromagnetic wave, the same area is targeted. The calibrated phase of the two or more antenna elements is calculated, and the observation point is determined in consideration of the overlapping area when the antenna device is mechanically moved .

According to the present invention, it is possible to calibrate all antenna elements while suppressing the cost.

It is a figure explaining the structural example of the antenna apparatus to which the antenna calibration method which concerns on Embodiment 1 of this invention can apply. It is a figure explaining an example of the area irradiated by each antenna beam formed by the antenna apparatus shown in FIG. 1, and the place where the pickup antenna is installed by the antenna calibration method which concerns on Embodiment 1 of this invention. It is a figure explaining the example of the antenna beam which can observe at an observation point by the antenna calibration method which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the resource allocation method according to the present invention will be described with reference to the drawings.

Embodiment 1.
FIG. 1 is a diagram illustrating a configuration example of an antenna device to which the antenna calibration method according to the first embodiment of the present invention can be applied.

This antenna device adopts an array feeding method. As shown in FIG. 1, this antenna device includes a reflector 1 and reflects an electromagnetic wave 4 emitted from each antenna element 2 (2-1 to n. N is an integer of 4 or more) constituting a phased array antenna. The antenna beam is formed by being reflected by the mirror 1. A feeding unit 3 (3-1 to n) for exciting the corresponding antenna element 2 is connected to each antenna element 2. In addition, a plurality of reflectors 1 may exist.

The code attached to the antenna element 2 following the hyphen and the number attached to the feeding unit 3 following the hyphen represent the correspondence between the antenna element 2 and the feeding unit 3. As a result, for example, the feeding unit 3-1 is connected to the antenna element 2-1 and the feeding unit 3-n is connected to the antenna element 2-n.

FIG. 2 is a diagram illustrating an example of an area irradiated by each antenna beam formed by the antenna device shown in FIG. 1 and an installation location of a pickup antenna by the antenna calibration method according to the first embodiment of the present invention. FIG. 2 shows an area 21 (21-1 to m. M is an integer of n or less) irradiated by each antenna beam and two arrangement locations 22 (22-1 and 22-2) of the pickup antenna. ing. Each area 21 corresponds to, for example, a cell.

The antenna beam that irradiates each area 21 is formed by electromagnetic waves 4 emitted by two or more antenna elements 2. Here, it is assumed that each antenna beam is formed by an electromagnetic wave 4 radiated by two antenna elements 2. For example, the antenna beam that irradiates the area 21-1 is the first antenna beam formed by the electromagnetic waves 4 emitted by the antenna elements 2-1 and 2-2, respectively. The antenna beam that irradiates the area 21-2 is a second antenna beam formed by the electromagnetic waves 4 emitted by the antenna elements 2-2 and 2-3, respectively. The antenna beam that irradiates the area 21-m is the m-th antenna beam formed by the electromagnetic waves 4 emitted by the antenna elements 2- (n-1) and 2-n, respectively. In this assumption, the relationship is m = n-1. The number of antenna elements 2 used for irradiation in the same area 21 may be 3 or more.

The plurality of antenna beams are formed so as to cover the entire service area of interest. Therefore, there is usually an overlapping portion between the adjacent areas 21. In the first embodiment, paying attention to this, the pickup antenna arrangement portion 22 is a portion where the adjacent areas 21 overlap. Observation of the antenna beam is performed at each arrangement point 22. For this reason, the arrangement location 22 will be referred to as "observation point 22" hereafter. Further, the portion where the adjacent areas 21 overlap is hereinafter referred to as "overlapping area".

When the observation points 22 are provided in the overlapping area, the number of observation points 22 can be reduced as compared with the case where the observation points 22 are provided for each area 21. By reducing the number of observation points 22, the number of receiving elements that receive electromagnetic waves is also reduced, and the installation cost is further reduced. A system that processes the signal output by the receiving element can also be constructed at a lower cost. As a result, the calibration of all the antenna elements 2 can be performed at a lower cost.

At the observation point 22-1, the first antenna beam that irradiates the area 21-1 and the second antenna beam that irradiates the area 21-2 are mainly observed. This means that the electromagnetic wave 4 radiated from the antenna elements 2-1 to 3 is mainly observed as described above. Specifically, the actual calibration at the observation point 22-1 is performed as follows, for example.

First, focusing on the first antenna beam, the calibration phase φ1 which is an appropriate phase amount between the antenna elements 2-1 and 2-2 is calculated. At the observation point 22-1, the electromagnetic waves radiated from the antenna elements 2-1 and 2-2 can be received. The calibration phase φ1 can be calculated by applying the element electric field vector method to these two antenna elements 2-1 and 2-2. Various processes including the calculation of the calibration phase φ1 are performed on the ground system side, which is a system constructed on the ground in the communication system that manages the antenna device, for example.

Alternatively, when the phase of the antenna element 2-1 is fixed and the phase of the antenna element 2-2 is rotated by 360 degrees or more, the phase in which the first antenna beam at the observation point 22-1 is maximized is observed. Therefore, the calibration phase φ1 between the antenna element 2-1 and the antenna element 2-2 can be calculated.

Next, at the same observation point 22-1, the calibration phase φ2 between the antenna elements 2-2 and 2-3 is calculated by focusing on the second antenna beam. Since the second antenna beam can be received at the observation point 22-1, the electromagnetic wave 4 radiated from the antenna element 2-2 and the antenna element 2-3 can be received. Therefore, the calibration phase φ2 can be calculated by applying the element electric field vector method to these two antenna elements 2-2, 2-3.

Alternatively, when the phase of the antenna element 2-2 is fixed and the phase of the antenna element 2-3 is rotated by 360 degrees or more, the phase in which the second antenna beam at the observation point 22-1 is maximized is observed. Therefore, the calibration phase φ2 can be calculated.

Assuming that the phase of the antenna element 2-1 is φ0, the phase of the antenna element 2-2 is φ0 + φ1 and the phase of the antenna element 2-3 is φ0 + φ1 + φ2, so that the antenna elements 2-1 to 2-3 are calibrated. Can be done. That is, at the same observation point 22-1, the phases of the three antenna elements 2-1 to 2-3 can be calibrated from the results of receiving the first antenna beam and the second antenna beam twice.

Next, the observation point 22 is changed, for example, the same processing as above is performed at the observation point 22-2, and the calibration phase φ3 between the antenna element 2-3 and the antenna element 2-4 from the third antenna beam. Make a calculation. Thereby, each calibration phase φ1 to φ3 of the three antenna elements 2 from the antenna element 2-2 to the antenna element 2-4 can be calculated. After that, the calibration phase of all the antenna elements 2 can be calculated by continuously performing the same processing at the other observation points 22.

The calculated information indicating each calibration phase or its contents is directly or indirectly transmitted from the ground system to the antenna device via the communication system, for example. As a result, the antenna device changes the setting of the power feeding unit 3 that needs to change the setting content. As a result, each antenna element 2 emits an electromagnetic wave 4 according to the calculated calibration phase.

When the phase of the antenna element 2 is rotated, the phase shifter mounted on the power feeding unit 3 may be used, or the set phase may be rotated. This is possible with an antenna device that performs digital beamforming.

In the first embodiment, the antenna device is for transmission. However, the antenna device may be for reception. This is because calibration is required even for reception, and both of the first embodiments can be applied to an antenna device for reception. However, in this case, it is necessary to radiate an electromagnetic wave from the observation point 22.

Further, in the first embodiment, the observation points 22 are provided in each overlapping area, but it is not always necessary to provide the observation points 22 in each overlapping area. Depending on the combination of the antenna elements 2 used for forming the antenna beam, for example, every other observation point 22 may be provided in the direction in which the overlapping areas are lined up. In that case, in the example shown in FIG. 1, the observation point 22-2 adjacent to the observation point 22-1 may be provided in the overlapping area of the area 21-3 and the adjacent area 21-4 (not shown).

Embodiment 2.
In the first embodiment, it is basically necessary to provide observation points 22 in each overlapping area. On the other hand, in the second embodiment, all the antenna elements 2 can be calibrated with fewer observation points 22. The reference numerals used in the first embodiment will be used as they are, and the description will be given by focusing only on the parts different from the first embodiment.

FIG. 3 is a diagram illustrating an example of an antenna beam that can be observed at an observation point by the antenna calibration method according to the second embodiment of the present invention.

Observation point 22-1 shown in FIG. 3 is located in the overlapping area of the area 21-2 irradiated by the second antenna beam and the area 21-3 irradiated by the third antenna beam. As a result, the overlapping area is different from that of FIG. This is due to the mechanical rotation of the antenna device in the satellite equipped with the antenna device shown in FIG. Observation point 22-1, which was located in the overlapping area of area 21-1 and area 21-2 before being mechanically rotated, is located in area 21-2 and area 21-2 by mechanically rotating the antenna device. It is designed to move within the overlapping area of 21-3.

The calibration phase at the observation point 22-1 is calculated, for example, by paying attention to the first and second antenna beams before the mechanical rotation, that is, in the state shown in FIG. As a result, the calibration phase φ1 between the antenna elements 2-1 and 2-2 and the calibration phase φ2 between the antenna elements 2-2 and 2-3 are calculated, respectively. Then, after mechanically rotating the device to shift to the state shown in FIG. 3, the calibration phase φ3 between the antenna elements 2-3 and 2-4 is calculated in the same manner as in the first embodiment.

By mechanically rotating the antenna device in this way, it becomes possible to calculate more calibration phases of the antenna elements 2 at one observation point 22. Therefore, it is possible to calibrate all the antenna elements 2 with fewer observation points 22 as compared with the first embodiment. As a result, the calibration of all the antenna elements 2 can be performed at a lower cost.

In the second embodiment, the antenna device is mechanically rotated, but the rotation is assumed to be one axis. However, the rotation is often possible with two or more axes. Therefore, in determining the observation point 22, it is necessary to consider the mechanically movable direction, movable range, and the like of the antenna device.

1 Reflector, 2,2-1 to n antenna element, 3,3-1 to n feeding part, 4 electromagnetic wave, 21,21 to 21-m area, 22, 22-1, 22-2 observation points.

Claims (1)

In an antenna calibration method applied to an antenna device having a reflector used for at least one of a plurality of antenna elements, reflection of electromagnetic waves radiated from each antenna element, and reflection of electromagnetic waves to each antenna element. ,
Assuming two or more antenna elements that target the same area among the plurality of antenna elements, the reception of the electromagnetic wave and the radiation of the electromagnetic wave are performed in the overlapping area where the two or more areas overlap. Determine the observation point to be used for at least one of them,
By receiving the electromagnetic wave at each of the determined observation points and radiating the electromagnetic wave at least one of them, the calibration phases of the two or more antenna elements targeting the same area are calculated .
The observation point is determined in consideration of the overlapping area when the antenna device is mechanically moved.
Antenna calibration method.

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