JP2024090249A - Calibration method for antenna measurement device, support jig, and antenna measurement device - Google Patents

Abstract

[Problem] To shorten the working time of calibration processing in an antenna measurement device. [Solution] A calibration method for an antenna measurement device including multiple probe antennas and a measurement device to which an antenna under measurement is connected via a first cable and to which the multiple probe antennas are each connected via a second cable, the method connects the first cable to a calibration antenna, places the calibration antenna in a position corresponding to the multiple probe antennas, sequentially faces each of the probe antennas, sequentially measures the characteristics of each path including the second cable connecting each of the probe antennas to the measurement device, and corrects characteristic differences between the multiple paths based on the measurement results. [Selected Figure] Figure 15

Description

The present invention relates to a calibration method for an antenna measurement device, a support jig, and an antenna measurement device.

Conventionally, there is known an antenna measurement device that includes a probe antenna and a measuring instrument (network analyzer). This antenna measurement device receives a transmitted electromagnetic wave transmitted from either the antenna under test or the probe antenna at the other antenna under test or the probe antenna, and measures antenna characteristics based on the received electromagnetic wave received by the antenna under test or the probe antenna (see, for example, Patent Documents 1 and 2).

Patent document 1 describes an antenna measurement device that includes multiple opposing antennas (probe antennas) that are arranged to surround the antenna under measurement. In the antenna measurement device described in Patent document 1, the multiple opposing antennas receive the transmitted electromagnetic waves transmitted from the antenna under measurement, and the directivity of the antenna under measurement is measured based on the received electromagnetic waves received by the opposing antennas.

Patent document 2 describes an electromagnetic wave measuring device that includes multiple probe antennas that receive transmitted electromagnetic waves transmitted from an antenna under test, and a measuring unit that measures the electromagnetic field distribution caused by the transmitted electromagnetic waves transmitted from the antenna under test based on the received electromagnetic waves received by the multiple probe antennas. Patent document 2 also describes a configuration in which the multiple probe antennas are provided around the antenna under test, and more specifically, a configuration in which the multiple probe antennas are provided on an arc or circle approximately centered on a holding unit that holds the antenna under test.

Japanese Patent Application Laid-Open No. 6-289081 JP 2005-502860 A

The antenna under test is connected to the measuring instrument by a first cable (also called the "cable for the antenna under test"), and each of the multiple probe antennas is connected to the measuring instrument by an individual second cable (also called the "cable for the probe antenna"). In other words, each probe antenna is connected to the measuring instrument via a separate path that includes each individual path. When measuring antenna characteristics with an antenna measuring device, it is desirable that the characteristic differences between each path be as small as possible. Therefore, a calibration process is performed at a specified timing to measure the characteristics of each path and correct the characteristic differences between each path. This makes it possible to suppress the characteristic differences between each path.

However, during this calibration process, the characteristics of each path were measured while sequentially connecting and disconnecting one first cable and multiple second cables. This made the calibration process time-consuming and labor-intensive.

The object of the present invention is to reduce the time required for calibration processing in an antenna measurement device.

A calibration method according to one embodiment is a method for calibrating an antenna measurement device that includes multiple probe antennas and a measuring instrument to which the antenna under measurement is connected via a first cable and to which the multiple probe antennas are each connected via a second cable, the method connects the first cable to a calibration antenna, places the calibration antenna in a position corresponding to the multiple probe antennas, faces the calibration antenna in sequence to each of the probe antennas, sequentially measures the characteristics of each path including the second cable connecting each of the probe antennas to the measuring instrument, and corrects characteristic differences between the multiple paths based on the results of the measurements.

In one embodiment of the support jig used in the calibration method, when the multiple probe antennas are arranged in a circular ring shape along a virtual circle surrounding the antenna under test, the support jig includes an axial member to which the calibration antenna is fixed, an axial holding member that holds the axial member so that the calibration antenna rotates in the circumferential direction of the multiple virtual circles, and a base on which the axial holding members are provided at predetermined intervals.

An antenna measurement device according to one embodiment includes a plurality of probe antennas and a measuring instrument to which the antenna under measurement is connected via a first cable and the plurality of probe antennas are each connected via a second cable. The plurality of probe antennas are arranged in a circular ring shape along an imaginary circle surrounding the antenna under measurement. The antenna measurement device also includes a calibration antenna to which the first cable is connected, and a support jig that supports the calibration antenna rotatably in the circumferential direction of the imaginary circle.

The present invention can reduce the time required for calibration processing in an antenna measurement device.

1 is a diagram showing a schematic configuration of an antenna measurement device according to an embodiment; FIG. 2 is a perspective view showing an example of a schematic configuration of an arrangement of an antenna under test and a probe antenna; FIG. 2 is a diagram showing the arrangement of a probe antenna according to an embodiment; 2 is an enlarged view showing an example of a configuration of a probe antenna according to an embodiment; FIG. FIG. 4 is an enlarged view showing an example of a configuration of a connecting portion according to an embodiment. FIG. 4 is a cross-sectional view showing a configuration of a connecting portion according to one embodiment. FIG. 13 is an enlarged view showing a modified example of a connecting portion according to an embodiment. FIG. 13 is an enlarged view showing a modified example of a connecting portion according to an embodiment. 13 is a cross-sectional view showing a modified example of a connecting portion according to an embodiment. FIG. FIG. 2 is a diagram showing an example of a block configuration of a measured antenna according to an embodiment; FIG. 2 is a diagram illustrating an example of a block configuration of an antenna characteristic measuring unit according to an embodiment. 1A and 1B are diagrams illustrating a method for measuring directivity according to an embodiment. 1A and 1B are diagrams illustrating a method for measuring directivity according to an embodiment. FIG. 2 is a perspective view showing a schematic configuration of a calibration antenna and a support jig used in a calibration process according to an embodiment. 10 is a flowchart illustrating an example of a procedure of a calibration process according to an embodiment. FIG. 11 is a diagram illustrating a calibration process according to an embodiment. FIG. 11 is a diagram illustrating a calibration process according to an embodiment.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
The antenna measurement device according to the present invention is a device for measuring the characteristics (antenna characteristics) of a measured antenna based on a received electromagnetic wave received by the measured antenna or a transmitted electromagnetic wave transmitted by the measured antenna. In one embodiment, the antenna measurement device is a device for receiving a transmitted electromagnetic wave transmitted from a probe antenna by the measured antenna, and measuring, for example, directivity as an antenna characteristic based on the received electromagnetic wave received by the measured antenna. That is, in one embodiment, the probe antenna functions as a transmitting antenna, and the measured antenna functions as a receiving antenna. However, since the directivity of an antenna is reversible and equal during transmission and reception, the probe antenna may function as a receiving antenna, and the measured antenna may function as a transmitting antenna.

In the antenna measurement device described as one embodiment, the "transmitted electromagnetic waves" transmitted by the probe antenna and the "received electromagnetic waves" received by the antenna under test are radio waves in terms of band. For this reason, in the following description, the "transmitted electromagnetic waves" will be referred to as "transmitted radio waves" and the "received electromagnetic waves" will be referred to as "received radio waves." Of course, the present invention can also be applied to antenna measurement devices that measure the characteristics of antennas that transmit and receive electromagnetic waves in bands other than radio waves.

<General configuration of antenna measurement device>
FIG. 1 is a block diagram showing an example of the configuration of an antenna measurement device according to an embodiment.
1, an antenna measurement device 10 according to an embodiment includes a plurality of probe antennas 30 (30a to 30o) housed in a housing 20, a positioner 40 on which an antenna under test (hereinafter also simply referred to as an "antenna") 100 is mounted, an antenna characteristic measuring section 50, a switch timing control section 60, a network analyzer 70 which is a measuring instrument, and a positioner control section 80. The antenna measurement device 10 is further configured to include, for example, a relay unit, switches SW1 and SW2 which include a coaxial changeover switch, a rail 90, etc. The plurality of probe antennas 30a to 30o are collectively referred to as probe antennas 30.

Each probe antenna 30 is connected to the switch SW1 by a data line Sd1, which corresponds to a probe antenna cable (also called a "second cable"). In FIG. 1, the data line Sd1 is shown as a single line, but in reality, the data line Sd1 is made up of multiple lines corresponding to each of the probe antennas 30a to 30o. That is, each probe antenna 30 is connected to the switch SW1 by multiple data lines Sd1 that are individually provided. The switch SW1 is also connected to the network analyzer 70 by a data line Sd2. Then, by switching the circuit of SW1, one of the multiple probe antennas 30 is connected to the network analyzer 70 via the data line Sd1 and the data line Sd2.

The antenna 100 is connected to the switch SW2 by a data line Sd3 corresponding to the cable for the antenna under test (also called the "first cable"), and the switch SW2 is connected to the network analyzer 70 by a data line Sd4. This data line Sd3 is used in common when measuring the characteristics of each probe antenna 30. The antenna 100 is configured to be able to transmit and receive a low-band horizontally polarized signal, a low-band vertically polarized signal, a high-band horizontally polarized signal, and a high-band vertically polarized signal, as described below. In FIG. 1, the data line Sd3 is shown as a single line, but in one embodiment, the data line Sd3 is composed of four lines corresponding to each of the above signals. The network analyzer 70 is connected to the antenna characteristic measuring unit 50 by a data line Sd5. The positioner 40 is connected to the positioner control unit 80 by a data line Sd6.

The antenna characteristic measuring unit 50 and the switch timing control unit 60 are connected by a control line Sc1, and the antenna characteristic measuring unit 50 and the positioner control unit 80 are connected by a control line Sc2. The switch timing control unit 60 and the switch SW1 are connected by a control line Sc3, and the switch timing control unit 60 and the switch SW2 are connected by a control line Sc4.

Although details will be described later, the antenna characteristic measuring unit 50 measures (estimates) the characteristics of the antenna 100, specifically, the circumferential directivity of the antenna 100, based on the received radio wave signal generated from the received radio waves received by the antenna 100. The switch timing control unit 60 appropriately controls the switches SW1 and SW2 to select the probe antenna 30 that transmits the transmitted radio waves, etc. The network analyzer 70, for example, performs A/D (analog-to-digital) conversion of the received radio wave signal (received radio wave signal) received by the antenna 100.

The antenna measurement device 10 also includes a calibration antenna 300 that is used during the calibration process of each path connecting each probe antenna 30 and the network analyzer 70, and a support jig 350 that supports the calibration antenna 300. The configurations of the calibration antenna 300 and the support jig 350, and the calibration process will be described in detail later.

<Arrangement of the measured antenna and probe antenna>
Fig. 2 is a perspective view showing an example of the arrangement of the antenna under test and the probe antenna. Fig. 3 is a plan view showing an example of the arrangement of the probe antenna. Fig. 4 is a perspective view showing an example of the configuration of the probe antenna. In Fig. 3, radio wave absorbing members and the like are omitted in order to make the arrangement of the probe antenna easier to see.

As described above, the antenna measurement device 10 includes a plurality of probe antennas 30 and a positioner 40 on which the antenna 100 is mounted. As an embodiment, the antenna measurement device 10 includes 15 probe antennas 30a to 30o, as shown in FIG. 2 and FIG. 3. The probe antennas 30a to 30o are arranged in a circular ring shape inside the housing 20. That is, the probe antennas 30a to 30o are arranged in a circular ring shape along a virtual circle VC that surrounds the antenna 100 (see FIG. 3). In other words, the "virtual circle VC" is a circle drawn by connecting the multiple probe antennas 30a to 30o arranged in a circular ring shape, and is a circle centered on the antenna 100. Therefore, when arranged in a circular ring shape around the antenna 100, the distance from each probe antenna 30 to the antenna 100 is approximately constant.

The positioner 40 is configured to be capable of moving the antenna under test 100 so that it passes inside the multiple probe antennas 30 (30a to 30o) arranged in a circular ring shape. Specifically, the positioner 40 is placed on a pair of rails 90 laid on the floor surface, and is configured to be capable of linear movement on the rails 90 inside the multiple probe antennas 30 arranged in a circular ring shape and along the rails 90. The antenna 100 has, for example, a cylindrical outer shape, and is mounted on the positioner 40 so that the axial direction (Z direction) of the antenna 100 is approximately horizontal. The antenna 100 is also mounted on the positioner 40 so that its axial direction (longitudinal direction) coincides with the direction in which the rails 90 are laid.

As a result, by moving the positioner 40 along the rail 90, the antenna 100 moves linearly along the Z direction together with the positioner 40. The antenna 100 is mounted on the positioner 40 so that when the positioner 40 is moved, the axial center of the antenna 100 passes through the center of the circle formed by the multiple probe antennas 30 (the center of the virtual circle VC).

When measuring the circumferential directivity of the antenna 100 as an antenna characteristic, the antenna 100 is moved by the positioner 40, as described in detail below, so that the multiple probe antennas 30 are arranged in a line around the antenna 100. In this state, the transmitted radio waves transmitted in sequence from each probe antenna 30 are received by the antenna 100, and the directivity of the antenna 100 is measured (estimated) based on the received radio waves received by the antenna 100.

As shown in FIG. 2, the antenna 100 is placed on, for example, a mounting base 200, which is then mounted on the positioner 40. The mounting base 200 is equipped with a number of wheels and is configured to be movable, and with the antenna 100 placed thereon, it is moved from another location to above the positioner 40 and fixed to the positioner 40. The structure of the mounting base 200 is merely an example and is not particularly limited. The antenna 100 does not necessarily have to be mounted on the mounting base 200, and may be mounted directly on the positioner 40, for example.

The housing 20 housing the multiple probe antennas 30 is provided in the X direction above the rails 90 that guide the movement of the positioner 40, straddling the rails 90. In other words, the rails 90 are laid in the Z direction so as to pass through the housing 20 housing the probe antennas 30. That is, the rails 90 are laid continuously in the Z direction from one outside of the tunnel section 21, which is the space formed by the housing 20, to the other outside.

Each of the multiple probe antennas 30 is fixed to a fixed panel 22, which is an example of a fixing member provided inside the housing 20. The fixed panel 22 is arranged along a direction (X direction) that is approximately perpendicular to the laying direction (Z direction) of the rail 90. In other words, the fixed panel 22 is arranged so that its surface coincides with the XY plane.

A substantially circular through-hole 23 is formed in the fixed panel 22. The multiple probe antennas 30 are arranged in a line on the outer periphery of the through-hole 23 and are each fixed to the fixed panel 22. The center of the circle formed by the multiple probe antennas 30 fixed to the fixed panel 22, that is, the center of the virtual circle VC, coincides with the center of the through-hole 23.

The lower end of the fixed panel 22 has a notch 24 formed by cutting out a part of the fixed panel 22. This notch 24 is formed continuously from the lower end surface of the fixed panel 22 to the through-hole 23. The formation of the notch 24 in the fixed panel 22 allows the positioner 40 to move linearly within the housing 20. In other words, the notch 24 is formed to be large enough that the positioner 40 can pass through the housing 20 together with the antenna 100 when the positioner 40 is moved.

In addition, multiple radio wave absorbers 25 are provided inside the housing 20 to absorb the transmitted radio waves transmitted from each probe antenna 30 and the reflected radio waves reflected around the probe antenna 30. It is preferable that the inner surface of the housing 20, particularly the periphery of the fixed panel 22, is covered with these multiple radio wave absorbers 25. Each radio wave absorber 25 is formed in a quadrangular pyramid shape that protrudes toward the inside of the housing 20, a so-called pyramid shape. The minimum frequency of radio waves that the radio wave absorber 25 absorbs changes depending on its height. For this reason, the height of the radio wave absorber 25 is appropriately set according to the minimum frequency of radio waves to be absorbed.

The radio wave absorber 25 is formed, for example, by forming a material, such as polystyrene foam beads, impregnated with graphite, into a quadrangular pyramid shape and attaching a ferrite tile to the bottom surface. The material of the radio wave absorber 25 is not particularly limited. Suitable materials for the radio wave absorber 25 include, for example, a material in which a conductive material, such as a carbon material or metal, is made into a fibrous form and kneaded into a resin, a dielectric absorbing material in which carbon particles are mixed with urethane or rubber, and a magnetic material such as ferrite.

The radio wave absorber 25 is preferably placed not only on the inner surface of the housing 20 but also on the floor surface around the antenna 100 (see FIG. 2). In FIG. 2, the radio wave absorber 25 is shown placed on the floor surface around the antenna 100 when the antenna 100 is positioned outside the housing 20, but in reality, the radio wave absorber 25 is placed on the floor surface around the antenna 100 when the antenna 100 is moved inside the housing 20. In short, the radio wave absorber 25 is preferably placed on and around a radio wave reflector that may affect the measurement results when measuring the antenna characteristics (when transmitting and receiving radio waves).

<Example of probe antenna configuration>
Each of the probe antennas 30 includes an antenna section 31. As shown in Fig. 4, the antenna section 31 includes a horizontally polarized antenna 31h and a vertically polarized antenna 31v that are attached crosswise so that horizontally polarized waves and vertically polarized waves of radio waves can be transmitted separately. The horizontally polarized antenna 31h is formed on a horizontally polarized substrate 32h, and the vertically polarized antenna 31v is formed on a vertically polarized substrate 32v, and these horizontally polarized substrate 32h and vertically polarized substrate 32v are attached so as to be perpendicular to each other.

Here, the antenna 100 has a cylindrical outer shape and is used with its central axis oriented vertically. In one embodiment, the antenna measurement device 10 measures the directivity of the antenna 100 in a lying position. That is, the directivity of the antenna 100 is measured with the central axis of the antenna 100 oriented horizontally (Z direction) (see FIG. 2). For this reason, the antenna section 31 of each probe antenna 30 is arranged along a plane (XY plane) perpendicular to the Z direction, which is the central axis direction of the antenna 100. That is, the horizontal polarization substrate 32h of the antenna section 31 is arranged along a plane (XY plane) including the virtual circle VC. In other words, each probe antenna 30 is arranged along the virtual circle VC so that the surface of the horizontal polarization substrate 32h faces the Z direction.

The horizontally polarized board 32h and the vertically polarized board 32v that constitute the antenna section 31 are formed, for example, from a printed circuit board or the like. The horizontally polarized antenna 31h and the vertically polarized antenna 31v are formed as horn antennas that utilize the copper foil portion of the printed circuit board. The size of the horizontally polarized board 32h and the vertically polarized board 32v is not particularly limited, but is, for example, about 200 mm long and about 220 mm wide. In addition, the frequency band of the radio waves (electromagnetic waves) received by the probe antenna 30 is not particularly limited, but is, for example, about 0.7 GHz to about 2.2 GHz.

The horizontally polarized antenna 31h is connected to a coaxial cable 33h. Similarly, the vertically polarized antenna 31v is connected to a coaxial cable 33v. These coaxial cables 33h and 33v form at least a part of the data line Sd1 (see FIG. 1). In other words, the horizontally polarized signal is input to the network analyzer 70 via the coaxial cable 33h, and the vertically polarized signal is input to the network analyzer 70 via the coaxial cable 33v.

<Probe antenna placement>
As described above, the probe antennas 30a to 30o are arranged side by side on the periphery of the circular through-hole 23 formed in the fixed panel 22 and fixed to the fixed panel 22 (see FIG. 3). As a result, the multiple probe antennas 30a to 30o are arranged side by side in an annular shape. As a result, the center of the circular through-hole 23 and the center of the circle formed by the multiple probe antennas 30a to 30o (the center of the virtual circle VC) coincide with each other.

In one embodiment, the multiple probe antennas 30 are arranged at equal intervals, except for the portion between probe antenna 30a and probe antenna 30o (the portion corresponding to cutout portion 24). Specifically, each probe antenna 30 is arranged at an interval such that the central angle between adjacent probe antennas 30 is approximately 22.5 degrees. Furthermore, probe antenna 30a and probe antenna 30o are arranged at an interval such that the central angle between them is approximately 45 degrees.

Each probe antenna 30 is fixed to the fixed panel 22 near the end of the probe antenna 30 on the radially outer side of the circle (imaginary circle VC) formed by the multiple probe antennas 30. Specifically, the probe antenna 30 includes a long plate-shaped support member 34 extending from the antenna section 31 in the radial direction of the through-hole 23, and is supported by the fixed panel 22 through this support member 34. That is, the horizontally polarized substrate 32h and the vertically polarized substrate 32v constituting the antenna section 31 are fixed to the fixed panel 22 via this support member 34. The support member 34 is fixed to the fixed panel 22 by a plurality of fastening members 35, for example, screws, etc. (see FIG. 5). The shape of the support member 34 is not particularly limited as long as it has the rigidity to support the probe antenna 30, and may be, for example, a columnar member. The material of the support member 34 is not particularly limited, but it is preferable that the material has little effect on the high-frequency characteristics of the horizontally polarized antenna 31h and the vertically polarized antenna 31v, for example, a resin, etc.

<Probe antenna connection structure>
5 and 6 are enlarged views showing a connection portion of the probe antenna, and FIG. 6 is a cross-sectional view corresponding to line AA in FIG.

As shown in Figures 3, 5 and 6, each of the equally spaced probe antennas 30 is connected to an adjacent probe antenna 30 by a connecting portion 36 extending in a tangential direction of a circle (imaginary circle VC) formed by the probe antennas 30. In other words, each probe antenna 30 is connected to an adjacent probe antenna 30 in the circumferential direction of the through-hole 23 formed in the fixed panel 22. That is, two adjacent probe antennas 30 are connected to each other by a connecting portion 36 extending in a tangential direction of the imaginary circle VC. In one embodiment, for example, the antenna portion 31 of each probe antenna 30 is connected to the adjacent antenna portion 31 by the connecting portion 36. That is, the antenna portions 31 of two adjacent probe antennas 30 are connected to each other by the connecting portion 36.

More specifically, of the probe antennas 30a to 30o arranged in a row at equal intervals around the periphery of the antenna 100, the probe antenna 30a located at the end of the row is connected only to the adjacent probe antenna 30b. Similarly, the probe antenna 30o located at the end of the row is connected only to the adjacent probe antenna 30h. The remaining probe antennas 30b to 30n are each connected to the adjacent probe antennas 30 on both sides. For example, the probe antenna 30b is connected to the adjacent probe antennas 30a and 30c. In one embodiment, the horizontal polarization substrates 32h that make up the antenna section 31 are each connected by a connecting section 36.

The connecting portion 36 is, for example, a plate-shaped connecting plate 37 that is a separate member from the horizontal polarization board 32h. The connecting plate 37 is disposed on one side of the horizontal polarization board 32h and is fixed to the horizontal polarization board 32h of the adjacent probe antenna 30. That is, the connecting plate 37 is attached to one surface in the Z direction of the horizontal polarization board 32h to connect the two adjacent horizontal polarization boards 32h. As an example, the connecting plate 37 is formed of an insulating board for a printed circuit board, for example, a glass epoxy board, and is fixed to the horizontal polarization board 32h of each probe antenna 30 by a fixing member 38. The material of the connecting plate 37 is not particularly limited, but it is preferable that it has little effect on the high-frequency characteristics of the horizontal polarization board 32h and the vertical polarization board 32v, and a non-conductive material, for example, a resin, is suitable.

The connecting plate 37 and the horizontally polarized substrate 32h of each probe antenna 30 each have an insertion hole 39 through which the fixing member 38 is inserted. The fixing member 38 is fitted into this insertion hole 39, so that the connecting plate 37 is fixed to each horizontally polarized substrate 32h. In one embodiment, each connecting plate 37 is fixed to each horizontally polarized substrate 32h by multiple, for example, two, fixing members 38. As a result, the horizontally polarized substrates 32h of two adjacent probe antennas 30 are connected to each other by the connecting plate 37 (connecting portion 36). The material of the fixing member 38 is not particularly limited, but it is preferable that, like the connecting plate 37, it is a material that has little effect on high frequency characteristics. In one embodiment, the fixing member 38 is, for example, a push rivet made of resin.

In this way, by connecting each probe antenna 30 with a connecting plate 37 arranged on one side of the horizontal polarization substrate 32h, it becomes easier to fix each probe antenna 30 to the fixed panel 22 while positioning it at equal intervals in a circular ring shape with high precision.

The procedure for attaching each probe antenna 30 to the fixed panel 22 is not particularly limited, but is preferably performed, for example, in the following procedure. First, the support member 34 of each probe antenna 30 is temporarily fixed to the fixed panel 22 by the fastening member 35. In other words, the support member 34 is attached to the fixed panel 22 by the fastening member 35 to the extent that the horizontal polarization substrate 32h of each probe antenna 30 can move slightly. In this state, the horizontal polarization substrates 32h of each probe antenna 30 are connected to each other by the connecting plate 37. Then, the fastening member 35 is further tightened to permanently fix the support member 34 to the fixed panel 22. This makes it easier to attach the probe antennas 30 to the fixed panel 22 while they are positioned at equal intervals with high accuracy. Therefore, the installation work time of the probe antennas 30 to the fixed panel 22 can be shortened.

As described above, the insertion holes 39 formed in the horizontal polarization board 32h and the connecting plate 37 are formed in the horizontal polarization board 32h and the connecting plate 37 by, for example, a printed circuit board processing machine. Therefore, the insertion holes 39 can be formed with high precision at desired positions in the horizontal polarization board 32h and the connecting plate 37. Therefore, by inserting the fixing members 38 into the insertion holes 39 and fixing the connecting plate 37 to the horizontal polarization board 32h of each probe antenna 30 by the fixing members 38, each probe antenna 30 can be positioned at equal intervals with high precision.

In this state, the fastening members 35 are tightened to fix the support members 34 to the fixed panel 22, so that each probe antenna 30 is attached to the fixed panel 22 with equal spacing and highly accurately positioned. This reduces the time required to attach each probe antenna 30 to the fixed panel 22. In addition, by connecting each probe antenna 30 with a connecting plate 37, the mounting structure of each probe antenna 30 to the fixed panel 22 can be simplified while maintaining high accuracy of the positional accuracy of each probe antenna 30. Therefore, the antenna measurement device 10 can be made smaller.

The position where the horizontally polarized substrate 32h of each probe antenna 30 is connected by the connecting plate 37 is not particularly limited, but in one embodiment, it is the tip of the horizontally polarized substrate 32h, that is, the end of the horizontally polarized substrate 32h opposite the fixed panel 22. That is, the horizontally polarized substrate 32h is fixed via the support member 34 at the radially outer end of the imaginary circle VC, and is connected by the connecting plate 37 at the radially inner end of the imaginary circle VC (the tip of the horizontally polarized substrate 32h) or near that end.

The horizontally polarized substrate 32h that constitutes each probe antenna 30 is a substantially rectangular substrate, so the gaps between each of the probe antennas 30 arranged in a ring shape become narrower toward the tip of the horizontally polarized substrate 32h. Therefore, by arranging the connecting plate 37 near the tip of the horizontally polarized substrate 32h, adjacent probe antennas 30 can be securely fixed together even if the area of the connecting plate 37 is relatively small. Furthermore, the smaller area of the connecting plate 37 can reduce material costs.

The configuration of the connecting portion 36 (connecting plate 37) is not particularly limited as long as it can connect adjacent probe antennas 30 in the tangential direction of the imaginary circle VC (the circumferential direction of the imaginary circle VC), that is, in the arrangement direction of the probe antennas 30. The connecting portion 36 may have the following configuration, for example.

<Modification 1 of the coupling portion of the probe antenna>
FIG. 7 is an enlarged plan view showing a modified example of the coupling portion of the probe antenna.
In the above-described configuration, the connecting plate 37 is disposed at the tip of the horizontal polarization substrate 32h, that is, at the end of the horizontal polarization substrate 32h radially inside the imaginary circle VC, but the arrangement of the connecting plate 37 is not particularly limited and may be determined appropriately. The shape and size of the connecting plate 37 are also not particularly limited, and may be any shape and size that can connect two adjacent horizontal polarization substrates 32h, and may be determined appropriately depending on the spacing of the probe antennas 30, etc.

For example, as shown in FIG. 7, the connecting plate 37 (connecting portion 36) may be disposed at the end of the horizontally polarized substrate 32h radially outside the imaginary circle VC, that is, at the end of the horizontally polarized substrate 32h on the fixed panel 22 side. Even with this configuration, the two adjacent probe antennas 30 can be well connected to each other by the connecting plate 37. In this case, the position where the support member 34 is fixed to the fixed panel 22 by the fastening member 35 and the position where the connecting plate 37 is fixed to the horizontally polarized substrate 32h by the fixing member 38 are relatively close to each other. In other words, the fixing position of each probe antenna 30 relative to the fixed panel 22 and the fixing position relative to the adjacent probe antenna 30 are relatively close to each other. This allows each probe antenna 30 to be fixed more firmly, and the occurrence of positional deviation of each probe antenna 30 fixed to the fixed panel 22 is suppressed.

As one embodiment, a configuration in which two adjacent horizontal polarization substrates 32h are connected to each other by a connecting plate 37 has been described, but for example, two adjacent support members 34 may be connected to each other by a connecting plate 37. Even with this configuration, it is easy to position each probe antenna 30 at equal intervals and fix it to the fixed panel 22. Therefore, the time required to attach each probe antenna 30 to the fixed panel 22 can be shortened.

<Modification 2 of the coupling portion of the probe antenna>
8 and 9 are enlarged views showing modified examples of the coupling portion of the probe antenna, and FIG. 9 is a cross-sectional view corresponding to the line BB in FIG.
In the embodiment described above, the connecting portion 36 is configured by a plate-shaped connecting plate 37 that is a separate member from the horizontal polarization substrate 32h, but the configuration of the connecting portion 36 is not limited to this. For example, as shown in Figures 8 and 9, the connecting portion 36 may be formed integrally with the horizontal polarization substrate 32h. In this case, the connecting portion 36 of each probe antenna 30 is overlapped with the connecting portion 36 of the adjacent probe antenna 30 in the Z direction and fixed by a fixing member 38.

For this reason, it is preferable that the connecting portion 36 is formed thinner than the thickness of the horizontal polarization substrate 32h. More specifically, it is preferable that the connecting portion 36 has a recess 36a on the surface facing the connecting portion 36 of the adjacent probe antenna 30. It is preferable that this recess 36a is formed with a thickness of about half the thickness of the horizontal polarization substrate 32h. This makes it possible to suppress bending deformation in the thickness direction (Z direction) of the horizontal polarization substrate 32h when the connecting portions 36 are overlapped. Therefore, two adjacent probe antennas 30 can be better connected to each other via the connecting portion 36.

As one embodiment, a configuration in which each probe antenna 30 is connected by one connecting portion 36 has been exemplified, but of course two adjacent probe antennas 30 may be connected by multiple connecting portions 36. As one embodiment, a configuration in which the probe antenna 30 includes an antenna portion 31 including a horizontally polarized substrate 32h and a vertically polarized substrate 32v has been exemplified, but the probe antenna 30 is not limited to this configuration. Regardless of the configuration of the probe antenna 30 itself, the above-mentioned effects can be obtained by connecting two adjacent probe antennas 30 via a connecting portion 36 extending in the tangent direction of the imaginary circle VC.

<Example of the configuration of the antenna under test>
Fig. 10 is a block diagram showing an example of the configuration of a measured antenna. In one embodiment, the antenna 100 that is the measurement target of the antenna measurement device 10 is, for example, a shared antenna, and includes a radio wave transmitting/receiving unit 110 and a measured antenna input/output unit 130 as shown in Fig. 10. Note that in this example, the measured antenna input/output unit 130 is realized, for example, by a connector and constitutes a part of the antenna 100, but there are also cases where it is realized, for example, by wiring and does not constitute a part of the antenna 100.

The radio wave transmitting/receiving unit 110 includes a low-band transmitting/receiving element unit 111 and a high-band transmitting/receiving element unit 112. The frequency bands of the radio waves transmitted and received by the low-band transmitting/receiving element unit 111 and the high-band transmitting/receiving element unit 112 are different. The frequency band of the radio waves transmitted and received by the high-band transmitting/receiving element unit 112 is higher than the frequency band of the radio waves transmitted and received by the low-band transmitting/receiving element unit 111. In this way, the radio wave transmitting/receiving unit 110 includes the low-band transmitting/receiving element unit 111 and the high-band transmitting/receiving element unit 112, so that the antenna 100 can transmit and receive radio waves in a relatively wide frequency range. The frequency band of the radio waves transmitted and received by the low-band transmitting/receiving element unit 111 may overlap with part of the frequency band of the radio waves transmitted and received by the high-band transmitting/receiving element unit 112.

The frequency bands of the radio waves transmitted and received by the low-band transmitting/receiving element unit 111 and the high-band transmitting/receiving element unit 112 are not particularly limited and may be set as appropriate. As an example, the frequency band of the radio waves transmitted and received by the low-band transmitting/receiving element unit 111 is 1 GHz or less, and the frequency band of the radio waves transmitted and received by the high-band transmitting/receiving element unit 112 is 1 GHz or more.

The measured antenna input/output unit 130 also includes a low-band input/output unit 131 and a high-band input/output unit 132. A low-band vertically polarized signal Slv and a low-band horizontally polarized signal Slh are input to the low-band input/output unit 131. The low-band vertically polarized signal Slv is a received signal of a vertically polarized radio wave input to the low-band transmitting/receiving element unit 111, and the low-band horizontally polarized signal Slh is a received signal of a horizontally polarized radio wave input to the low-band transmitting/receiving element unit 111. The high-band vertically polarized signal Shv and a high-band horizontally polarized signal Shh are input to the high-band input/output unit 132. The high-band vertically polarized signal Shv is a received signal of a vertically polarized radio wave input to the high-band transmitting/receiving element unit 112, and the high-band horizontally polarized signal Shh is a received signal of a horizontally polarized radio wave input to the high-band transmitting/receiving element unit 112.

<Explanation of antenna characteristic measurement section>
Next, a description will be given of the configuration of the antenna characteristic measuring unit 50 included in the antenna measurement device 10. In one embodiment, the antenna characteristic measuring unit 50 measures (estimates) the circumferential directivity of the antenna 100 based on the radio waves received by the antenna 100 as described above. That is, the antenna characteristic measuring unit 50 measures the horizontal plane directivity of the antenna 100.

Figure 11 is a block diagram showing an antenna characteristic measurement unit constituting an antenna measurement device. As shown in Figure 11, the antenna characteristic measurement unit 50 includes an input unit 51, a directivity measurement unit 52, an output unit 53, and a memory unit 54.

The input unit 51 inputs the received radio wave signal information sent from the network analyzer 70 to the directivity measurement unit 52. The received radio wave signal information is digital signal information obtained by converting the received radio wave received by the antenna 100 into a received radio wave signal, which is an analog electrical signal, and then A/D converting the received radio wave signal. The input unit 51 also inputs various types of information, such as a timing signal and position information of the antenna 100, to the directivity measurement unit 52 as digital signals. Furthermore, the input unit 51 may also have a function as a man-machine interface.

The directivity measurement unit 52 measures (estimates) the circumferential directivity (horizontal plane directivity) of the antenna 100 from various information including the received radio signal information input from the input unit 51. The directivity measurement unit 52 can be realized, for example, by using a microcomputer equipped with a CPU. A computer program (antenna directivity measurement program) for functioning as the directivity measurement unit 52 is pre-installed in the microcomputer. By executing this program, the microcomputer functions as multiple information processing units equipped in the directivity measurement unit 52.

As one embodiment, the directivity measurement unit 52 includes a trigger signal generation unit 521, a transmission radio wave information generation unit 522, a reception radio wave information analysis unit 523, and a correction unit 524. The trigger signal generation unit 521 generates a trigger signal for starting the measurement of directivity, that is, the transmission and reception of radio waves between the probe antenna 30 and the antenna 100. The trigger signal generation unit 521 also generates a trigger signal for stopping the movement of the antenna 100 (positioner 40). These trigger signals are transmitted at predetermined timing to the positioner control unit 80, the switch timing control unit 60, the network analyzer 70, etc.

The transmission radio wave information generating unit 522 generates information such as frequency information, modulation information, and amplification information for transmitting transmission radio waves (horizontally polarized radio waves and vertically polarized radio waves) from each probe antenna 30. This information is generated taking into consideration characteristic information of each probe antenna 30 that transmits the transmission radio waves, characteristic information of the interface relationship with each probe antenna 30, and the like. Note that the information generation method by the transmission radio wave information generating unit 522 is a known technique, and therefore a detailed description of the information generation method will be omitted.

The received radio wave information analysis unit 523 analyzes the received radio wave signal information (received horizontally polarized radio wave signal information and received vertically polarized radio wave signal information) sent from the network analyzer 70. The received radio wave information analysis unit 523 converts the received radio wave signal information, which includes, for example, amplitude information and phase information of the received radio wave signal, into discrete data for the central angle in the circumferential direction (the arrangement angle of each probe antenna 30) and the distance in the Z direction.

The correction unit 524, which will be described in detail later, appropriately corrects the analysis data analyzed by the received radio wave information analysis unit 523, for example, according to the measurement point where the received radio wave was received. The output unit 53 outputs various information generated by the directivity measurement unit 52 to the outside. As an example, the output unit 53 outputs transmission radio wave signal information for generating a transmission radio wave signal to be transmitted to the probe antenna 30. That is, the output unit 53 outputs transmission radio wave signal information based on the above information generated by the transmission radio wave information generation unit 522 to the network analyzer 70 at the timing when the trigger signal for starting measurement generated by the trigger signal generation unit 521 is transmitted. Note that when the transmission radio wave signal information is transmitted from the output unit 53, the network analyzer 70 functions as a transmission radio wave generation device that generates a transmission radio wave signal from the transmission radio wave signal information.

The memory unit 54 stores information input from the input unit 51 to the directivity measurement unit 52, inputs and outputs information between the directivity measurement unit 52, and stores the information that is input and output. The memory unit 54 can also store information between each functional block in the directivity measurement unit 52. Furthermore, the memory unit 54 can also store information to be output from the output unit 53.

The storage unit 54 is configured with a computer-readable recording medium. For example, the storage unit 54 is configured to include at least one of a ROM (Read Only Memory), a RAM (Random Access Memory), etc. In addition to a ROM and a RAM, the storage unit 54 may also be configured to include at least one of an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), etc. The storage unit 54 may also be called a register, a cache, a main memory (primary storage device), etc. The storage unit 54 can also store a program (program code) capable of executing the processing according to the present invention, a software module, etc.

The antenna characteristic measuring unit 50 is configured as a device implemented by hardware, such as a semiconductor circuit or a microcomputer, that executes processing related to the functions in the block diagram. Alternatively, it may be configured by a general-purpose server device or a virtual server built on a cloud computing service. The antenna characteristic measuring unit 50 may also be configured by a CPU (Central Processing Unit) (not shown).

The antenna characteristic measuring unit 50, excluding the memory unit 54, may be executed by middleware such as an OS (Operating System) deployed onto memory from a recording device such as an HDD (Hard Disk Drive), or by software running on the OS.

The antenna characteristic measuring unit 50 may be configured by appropriately combining these hardware implementations and software implementations. Furthermore, the antenna characteristic measuring unit 50 is not limited to a configuration in which the entire unit is implemented in a single housing, and may be configured such that some functions are implemented in separate housings and these housings are interconnected by a communication cable or the like. In other words, the implementation form of the antenna characteristic measuring unit 50 is not particularly limited, and can be flexibly changed as appropriate depending on the system environment, etc.

Furthermore, the antenna characteristic measurement unit 50 may be realized in combination with other configurations of the antenna measurement device 10. For example, the antenna characteristic measurement unit 50 may be realized by an implementation that is added to other hardware of the antenna measurement device 10, or an implementation that is added to other software of the antenna measurement device 10.

<Explanation of the operation of the antenna measurement device>
12 and 13 are diagrams for explaining the operation of the antenna measurement device, and are diagrams for explaining the positional relationship between the position of the probe antenna from which the transmission radio wave is transmitted and each measurement point of the antenna under measurement. The operation of the antenna measurement device 10, mainly the operation of the antenna characteristic measurement unit, will be explained below.

When measuring directivity using the antenna measurement device 10, radio waves are transmitted sequentially from the multiple probe antennas 30 while the antenna 100 is moved linearly in its axial direction (Z direction), and the transmission signals transmitted from each probe antenna 30 are received at different measurement points on the antenna 100. Then, received signal information obtained from the received radio waves received at each measurement point is analyzed to obtain analytical data such as discrete data, and this analytical data is corrected as necessary. This makes it possible to measure the circumferential directivity of the antenna 100 in a relatively short time.

As one embodiment, the antenna measurement device 10 includes 15 probe antennas 30 (30a to 30o) as described above. The transmitted radio waves transmitted from each probe antenna 30 are received at each measurement point arranged at a predetermined interval on the antenna 100. The directivity is measured while the antenna 100 is moved linearly in the Z direction along its central axis C1, as shown in Figures 12 and 13. On the antenna 100, measurement points P1 to P15 corresponding to the transmitted radio waves transmitted from each probe antenna 30a to 30o are arranged at a predetermined distance Da in the Z direction.

Here, the measurement points P1 to P15 of the antenna 100 are considered to be arranged in a straight line on the central axis C1. Taking into account the orientation of the probe antennas 30a to 30o, the measurement points P1 to P15 are arranged in a spiral around the central axis C1.

Furthermore, each of the probe antennas 30a to 30o is positioned at a predetermined distance Db from the central axis C1 of the antenna 100. In other words, the antenna 100 is positioned so that its axial center C1 coincides with the center of the circle formed by the multiple probe antennas 30.

When measuring directivity, first, a signal (measurement start information signal) instructing the start of directivity measurement is input from the input unit 51 of the antenna characteristic measurement unit 50 to the directivity measurement unit 52 in response to, for example, a switch operation by an operator. When the measurement start information signal is input to the directivity measurement unit 52, a trigger signal is generated by the trigger signal generation unit 521 to start directivity measurement. The generated trigger signal is transmitted from the directivity measurement unit 52 to the positioner control unit 80 via the output unit 53.

The positioner control unit 80, which receives the trigger signal, sequentially reads the position information of the positioner 40 and moves the positioner 40, on which the antenna 100 is mounted, along the rail 90 toward the inside of the housing 20. When the positioner control unit 80 receives a signal inquiring about the position of the antenna 100, it appropriately transmits the position information of the antenna 100 to the antenna characteristic measurement unit 50 (directivity measurement unit 52) in response.

The positioner control unit 80 continuously moves the positioner 40 on which the antenna 100 is mounted at a substantially constant speed until the directivity measurement of the antenna 100 is completed. However, the moving speed of the antenna 100 (positioner 40) during directivity measurement does not necessarily have to be constant and may be changed as appropriate as necessary. For example, the positioner 40 may be stopped when the antenna 100 receives the transmission radio waves transmitted from the probe antenna 30, and the positioner 40 may be moved when the antenna 100 is not receiving the transmission radio waves.

When the movement of the antenna 100 (positioner 40) begins, a signal inquiring about the position of the antenna 100 is continuously transmitted from the antenna characteristic measurement unit 50 (directivity measurement unit 52) to the positioner control unit 80. Then, when the antenna 100 moves to a position where it can receive the transmission radio wave, a signal indicating this (reception preparation completion signal) is transmitted to the antenna characteristic measurement unit 50. For example, when the measurement point P1 of the antenna 100 moves in the Z direction to a predetermined position Z1 corresponding to the probe antenna 30 (see FIG. 12), a reception preparation completion signal is input to the antenna characteristic measurement unit 50. When the reception preparation completion signal is received by the antenna characteristic measurement unit 50, a trigger signal created by the trigger signal generation unit 521 is transmitted to the switch timing control unit 60 and the network analyzer 70. In addition, information generated by the transmission radio wave information generation unit 522 is transmitted from the antenna characteristic measurement unit 50 to the probe antenna 30a via the network analyzer 70. This starts the transmission of the transmission radio wave from the probe antenna 30a.

In one embodiment, the trigger signal sent from the antenna characteristic measuring unit 50 to the switch timing control unit 60 includes, for example, information for selecting one of the multiple probe antennas 30 (e.g., probe antenna 30a) that transmits the transmission radio waves. This trigger signal also includes information for selecting one of the horizontally polarized antenna 31h or the vertically polarized antenna 31v that constitutes the probe antenna 30. By sending a trigger signal including such information, one probe antenna 30a that transmits the transmission radio waves is selected, and switching is performed between the horizontally polarized antenna 31h and the vertically polarized antenna 31v for the selected probe antenna 30a.

The transmitted radio waves sent from the probe antenna 30a are received at the measurement point P1 of the antenna 100. The received radio waves received at the measurement point P1 of the antenna 100 are converted into a received radio signal as an analog electrical signal by the antenna 100, and the received radio signal is input to the network analyzer 70 via the switch SW2. The received radio signal is A/D converted by the network analyzer 70, and input to the antenna characteristic measuring unit 50 as received radio signal information, which is digital information. In this case, the network analyzer 70 functions as a received radio signal information generating device.

The received radio wave signal information input to the antenna characteristic measuring unit 50 is temporarily stored in, for example, the memory unit 54 and analyzed by the received radio wave information analyzing unit 523. As described above, the received radio wave information analyzing unit 523 converts the received radio wave signal information, which includes, for example, amplitude information and phase information of the received radio wave signal, into analysis data such as discrete data for the central angle in the circumferential direction (the arrangement angle of each probe antenna 30) and the distance in the Z direction. This analysis data is also temporarily stored in, for example, the memory unit 54.

When received radio signal information is input to the antenna characteristic measuring unit 50, the antenna characteristic measuring unit 50 transmits a radio wave acquisition signal to the switch timing control unit 60. When the radio wave acquisition signal is input to the switch timing control unit 60, the switch timing control unit 60 switches the circuit of switch SW1 to turn the probe antenna 30a to the OFF state, and switches the circuit of switch SW2 to turn the antenna 100 to the OFF state.

As described above, in one embodiment, during the directivity measurement of the antenna 100, the antenna 100 (positioner 40) moves at a substantially constant speed. Then, as shown in FIG. 13, when the antenna 100 moves a predetermined distance Da in the Z direction and the measurement point P2 reaches a position Z1 corresponding to the probe antenna 30, a reception preparation completion signal is input from the positioner control unit 80 to the antenna characteristic measurement unit 50. As a result, a trigger signal for transmitting the next transmission radio wave from the probe antenna 30b is generated by the trigger signal generation unit 521. This trigger signal is transmitted from the antenna characteristic measurement unit 50 to the switch timing control unit 60 and the network analyzer 70. In addition, information generated by the transmission radio wave information generation unit 522 is transmitted from the antenna characteristic measurement unit 50 to the probe antenna 30b via the network analyzer 70. As a result, transmission of the transmission radio wave from the probe antenna 30b is started.

The transmitted radio waves sent from the probe antenna 30b are received at the measurement point P2 of the antenna 100. The received radio waves received at the measurement point P2 of the antenna 100 are converted into a received radio signal as an analog electrical signal by the antenna 100, and the received radio signal is input to the network analyzer 70 via the switch SW2. The received radio signal is A/D converted by the network analyzer 70, and input to the antenna characteristic measurement unit 50 as received radio signal information, which is digital information.

The received radio wave signal information input to the antenna characteristic measurement unit 50 is analyzed by the received radio wave information analysis unit 523 in the same manner as when radio waves are received at measurement point P1, and is converted into analysis data such as discrete data for the central angle in the circumferential direction and the distance in the Z direction. In addition, a radio wave acquisition signal is sent from the antenna characteristic measurement unit 50 to the switch timing control unit 60, and the probe antenna 30b and the antenna 100 are each switched to the OFF state by the switch timing control unit 60.

Then, the analysis data analyzed by the received radio wave information analysis unit 523 is appropriately corrected by the correction unit 524 according to, for example, the measurement point at which the received radio wave was received. In detail, the correction unit 524 appropriately corrects the analysis data to generate correction data based on, for example, the difference between the distance from the probe antenna 30 transmitting the transmitted radio wave to the "actual measurement point" of the antenna 100 and the distance from the probe antenna 30 transmitting the transmitted radio wave to the "virtual measurement point" of the antenna 100. This correction data is also temporarily stored in, for example, the memory unit 54.

Here, the "actual measurement point" is the measurement point of the antenna 100 where the transmission radio wave transmitted from each probe antenna 30 is actually measured. In other words, the "actual measurement point" is approximately the same as the point where the extension line extended from the probe antenna 30 transmitting the transmission radio wave intersects the central axis C1 of the antenna at right angles. For example, as shown in FIG. 12, when a transmission radio wave is transmitted from the probe antenna 30a, the transmission radio wave is received at the measurement point P1 of the antenna 100. Therefore, the distance from the probe antenna 30a to the "actual measurement point" of the antenna 100 corresponds to the distance O-P1 in the figure. Also, for example, as shown in FIG. 13, when a transmission radio wave is transmitted from the probe antenna 30b, the transmission radio wave is received at the measurement point P2 of the antenna 100. Therefore, the distance from the probe antenna 30b to the "actual measurement point" of the antenna 100 corresponds to the distance O-P2 in the figure. In this way, the distance from each probe antenna 30 to the "actual measurement point" of the antenna 100 corresponds to the distance Db between the antenna 100 and the probe antenna 30.

On the other hand, a "virtual measurement point" is a measurement point on antenna 100 where it is originally desired to measure the transmitted radio waves transmitted from each probe antenna 30. In one measurement in which transmitted radio waves are transmitted in sequence from probe antenna 30a to probe antenna 30o, the above-mentioned "virtual measurement point" is set to one point. In the example shown in Figures 12 and 13, the transmitted radio waves transmitted from each of probe antennas 30a to 30o are measured at measurement points P1 to P15, respectively, and of these, measurement point P1 is the "virtual measurement point".

In this case, the distance from probe antenna 30a to the "virtual measurement point" of antenna 100 corresponds to O-P1 in the figure, and is the same as the distance from probe antenna 30a to the "actual measurement point" of antenna 100. Therefore, there is no need to correct the analysis data based on the radio waves received at measurement point P1 of antenna 100.

The distance from probe antenna 30b to the "virtual measurement point" of antenna 100 corresponds to the distance Dc between O-P1 in FIG. 13, and does not match the distance Db from probe antenna 30b to the "actual measurement point" of antenna 100. Therefore, the analysis data based on the transmitted radio waves sent from probe antenna 30b (received radio waves received at measurement point P2 of antenna 100) is corrected by correction unit 524.

That is, the correction unit 524 appropriately corrects the analysis data based on the radio waves received at each measurement point P2 to P15 based on the difference between the distance from each probe antenna 30 to the "virtual measurement point" of the antenna 100 and the distance from each probe antenna 30 to the "real measurement point" of the antenna 100. In other words, the correction unit 524 appropriately corrects the analysis data based on the radio waves received at each measurement point where the "virtual measurement point" does not match the "real measurement point". The method of correcting the analysis data by the correction unit 524 is not particularly limited, and any known method may be used, so a detailed description will be omitted here. In addition, as one embodiment, an example in which the measurement point P1 is set as the "virtual measurement point" has been described, but of course the measurement points P2 to P15 other than the measurement point P1 may be set as the "virtual measurement point".

Then, the antenna measurement device 10 repeats the same process for the remaining probe antennas 30c to 30o. The antenna measurement device 10 repeats the above process each time the antenna 100 moves a predetermined distance Da in the Z direction. In other words, the directivity measurement unit 52 repeats sending the above trigger signal each time the antenna 100 moves a predetermined distance Da until it receives received radio wave signal information based on the transmitted radio waves sent from the last probe antenna 30o.

When a signal indicating that the antenna 100 has moved beyond the last measurement point P15 is input to the directivity measurement unit 52, a trigger signal to stop the movement of the antenna 100 (positioner 40) is generated by the trigger signal generation unit 521 and transmitted to the positioner control unit 80. This stops the movement of the antenna 100 (positioner 40) and ends one directivity measurement. Then, as described above, the directivity around (circumferential direction) of the antenna 100 is measured (estimated) based on the correction data corrected by the correction unit 524.

The number of times that directivity measurement is performed on the antenna 100 is not particularly limited. The directivity measurement of the antenna 100 may be performed multiple times in succession in the axial direction (Z direction) of the antenna 100. In this case, the above-mentioned predetermined distance Da can be set to any value by the antenna characteristic measuring unit 50. However, it is preferable that the above-mentioned predetermined distance Da is set to the same value while one directivity measurement is being performed, that is, while the transmission radio waves are transmitted in order from the probe antenna 30a to the probe antenna 30o.

As described above, in one embodiment, the antenna measurement device 10 receives the transmitted radio waves sent from the probe antennas 30a to 30o at each measurement point P1 to P15 of the antenna 100 while moving the antenna 100 in the axial direction (Z direction). The antenna measurement device 10 then corrects the analysis data based on the received radio waves received at each measurement point P1 to P15 to be analysis data received at the same "virtual measurement position" of the antenna 100 (for example, measurement point P1).

This allows the circumferential radio wave characteristics of the antenna 100 to be measured without repeatedly moving and stopping the antenna 100 in the axial direction (Z direction). As a result, the circumferential directivity of the antenna 100 can be measured in a relatively short time. As described above, each probe antenna 30 is attached to the fixed panel 22 in a highly accurately positioned state by connecting adjacent probe antennas 30 with the connecting parts 36. This also reduces misalignment of each probe antenna 30 during directivity measurement. Therefore, the circumferential directivity of the antenna 100 can be measured more accurately.

In one embodiment, in the antenna measurement device 10 described above, the mounting table 200 on which the antenna 100 is placed is mounted on the positioner 40, and the movement of the positioner 40 is controlled to move the antenna 100 at a constant speed. Therefore, the position of the antenna 100 (positioner 40) in the Z direction can be accurately determined from the moving speed and moving time of the positioner 40. Therefore, the positioner control unit 80 may transmit a reception preparation completion signal or the like to the antenna characteristic measurement unit 50 at a predetermined timing without acquiring position information of the positioner 40 (antenna 100). Even in this case, the transmitted radio waves from each probe antenna 30 can be properly received at each measurement point P1 to P15 of the antenna 100.

(Explanation of the calibration process)
As described above, the antenna measurement device 10 includes a plurality of probe antennas 30. Each probe antenna 30 is connected to the network analyzer 70 via an individually provided data line Sd1. That is, the antenna measurement device 10 includes a plurality of paths connecting each of the probe antennas 30a to 30o to the network analyzer 70. For this reason, it is desirable to measure the characteristics of each path at a predetermined timing and perform a calibration process to correct the characteristic difference between each path so that the characteristic difference between each path is reduced.

In one embodiment, the antenna measurement device 10 performs a calibration process using the method described below. First, the configuration of the calibration antenna 300 and support jig 350 used in the calibration process will be described. Figure 14 is a perspective view showing the schematic configuration of the calibration antenna and support jig.

As one embodiment, the antenna measurement device 10 includes a calibration antenna 300 used when performing the calibration process as described above, and a support jig 350 that rotatably supports the calibration antenna 300. During the calibration process, as shown by the dotted line in FIG. 1, the data line Sd3, which is the first cable removed from the antenna 100, which is the antenna to be measured, is connected to the calibration antenna 300.

The calibration antenna 300 is also placed at a position corresponding to the multiple probe antennas 30. That is, the calibration antenna 300 is placed within a circle (imaginary circle VC) formed by the multiple probe antennas 30. In other words, the calibration antenna 300 is placed within the through-hole 23 of the fixed panel 22 to which the multiple probe antennas 30 are fixed.

The calibration antenna 300 is then rotated to face each of the probe antennas 30 in turn, and the characteristics of each path, including the data line Sd1, which is the second cable connecting each probe antenna 30 facing the calibration antenna 300 to the network analyzer 70, which is a measuring instrument, is measured. After that, the characteristic differences between the multiple paths are corrected based on the results of this measurement.

This calibration antenna 300 is for receiving radio waves transmitted from each probe antenna 30 or for transmitting radio waves to each probe antenna 30 when performing the calibration process. In the calibration process, the calibration antenna 300 is used in common by each of the multiple probe antennas 30.

As shown in FIG. 14, the calibration antenna 300 has the same shape as the probe antenna 30. That is, like the probe antenna 30, the calibration antenna 300 has an antenna section 301 including a horizontally polarized antenna 301h and a vertically polarized antenna 301v. The horizontally polarized antenna 301h is formed on a horizontally polarized substrate 302h, and the vertically polarized antenna 301v is formed on a vertically polarized substrate 302v, and these horizontally polarized substrate 302h and vertically polarized substrate 302v are attached so as to be perpendicular to each other. Of course, the configuration of the calibration antenna 300 is not limited to this, and it is sufficient if it can be placed opposite each probe antenna 30 and the characteristics of each path can be measured in that state.

To achieve this, it is preferable that the calibration antenna 300 has as simple a structure as possible and is also lightweight. As described below, the calibration antenna 300 is rotatably supported by a support jig 350 so that it can face each probe antenna 30. If the calibration antenna 300 has a simple structure and is lightweight, it is easier to rotatably support the calibration antenna 300 by the support jig 350. As a result, the structure of the support jig 350 can be simplified and the support jig 350 can be made smaller.

The support jig 350 that supports the calibration antenna 300 includes an axis member 351 to which the calibration antenna 300 is fixed, a pair of axis holding members 352 that hold both ends of the axis member, and a base portion 353 on which the axis holding members 352 are arranged at a predetermined interval.

The shaft member 351 is a rod-shaped member with a circular cross section, to which the calibration antenna 300 is fixed and which serves as the center of rotation of the calibration antenna 300. The calibration antenna 300 is fixed to the center of the shaft member 351 in the longitudinal direction. The calibration antenna 300 is arranged so that the surface of the vertical polarization substrate 302v is aligned along the longitudinal direction (axial direction) of the shaft member 351. The material of the shaft member 351 is not particularly limited, but is preferably a material that has little effect on high-frequency characteristics, and for example, a resin material is preferably used. Both ends of the shaft member 351 in the longitudinal direction (axial direction) are rotatably held by a pair of shaft holding members 352. That is, the shaft member 351 is held by the shaft holding member 352 so that the calibration antenna 300 can rotate along the juxtaposition direction of the multiple probe antennas 30.

The pair of shaft holding members 352 are so-called shaft holders, and are arranged to face each other with a predetermined interval between them and fixed to the base 353. The base 353 is a member that serves as the base of the support jig 350, and has a pair of support columns 354 that are arranged at a predetermined interval. The pair of shaft holding members 352 are fixed near the tip end (the upper end in FIG. 14) of each support column 354. The material of the base 353 is preferably a material that has little effect on high-frequency characteristics, and in one embodiment, wood is used. Of course, the material of the base 353 is not limited to wood, and may be, for example, a resin material. The structure of the base 353 is not particularly limited, and it is sufficient that the shaft holding members 352 can be arranged at a predetermined interval so that the shaft member 351 can be rotated together with the calibration antenna 300.

The shaft holding members 352 each have a clamp mechanism 355, and are configured to be able to fix the shaft member 351 at a position where the calibration antenna 300 faces each of the probe antennas 30. The configuration of the clamp mechanism 355 provided on the shaft holding members 352 is not particularly limited, and an existing one may be adopted, so here, an example of the configuration of the clamp mechanism 355 will be briefly described.

In one embodiment, the shaft holding member 352 has a slit 356 formed by cutting out a part of the outer circumference of the hole into which the shaft member 351 is inserted. Although not shown, a fastening member for adjusting the spacing of the slit 356 is provided at the portion of the shaft holding member 352 corresponding to the slit 356. A clamp lever 357 is attached to this fastening member, and the spacing of the slit 356 is adjusted by the operator operating this clamp lever 357. That is, when the operator rotates the clamp lever 357 in one direction, the spacing of the slit 356 narrows, and the shaft member 351 is clamped by the shaft holding member 352 to fix the shaft member 351. When the operator rotates the clamp lever 357 in the opposite direction to the clamping direction, the spacing of the slit 356 widens, and the clamping of the shaft member 351 by the shaft holding member 352 weakens, allowing the shaft holding member 352 to rotate (pivot).

By using such a support jig 350 for the calibration process, the calibration antenna 300 can be easily fixed in the desired orientation. In other words, the calibration antenna 300 can be easily fixed facing each probe antenna 30. This improves the workability of the calibration process. Therefore, the work time for the calibration process in the antenna measurement device 10 can be shortened.

The calibration process (calibration method) will be described below. FIG. 15 is a flowchart showing an example of the calibration process. FIG. 16 and FIG. 17 are plan views explaining the calibration process.

As shown in FIG. 15, first, the support jig 350 supporting the calibration antenna 300 is placed so that the calibration antenna 300 is positioned in the Z direction corresponding to the probe antenna 30 (step S1). Specifically, the mounting table 200 mounted on the positioner 40 is lowered from the positioner 40, and the support jig 350 supporting the calibration antenna 300 is mounted on the positioner 40. At this time, the axial direction of the shaft member 351 is set to the Z direction, and the axial center of the shaft member 351 is aligned with the center of the circle (virtual circle VC) formed by the multiple probe antennas 30. Then, the positioner 40 is moved in the Z direction until the calibration antenna 300 is positioned in a position corresponding to the multiple probe antennas 30. That is, the calibration antenna 300 is moved to a predetermined position Z1 (see FIG. 12).

Then, the calibration antenna 300 is made to face a predetermined probe antenna 30, and the shaft member 351 is fixed by the shaft holding member 352 (step S2). That is, the calibration antenna 300 is rotated together with the shaft member 351 of the support jig 350, so that the calibration antenna 300 faces the predetermined probe antenna 30. For example, as shown in FIG. 16, first, the calibration antenna 300 is made to face the probe antenna 30a.

Here, "the calibration antenna 300 faces the probe antenna 30" means that the horizontally polarized substrate 302h of the calibration antenna 300 and the horizontally polarized substrate 32h of the probe antenna 30 overlap when viewed in the radial direction of the shaft member 351. In this case, the vertically polarized substrate 302v of the calibration antenna 300 and the vertically polarized substrate 32v of the probe antenna 30 also naturally overlap when viewed in the radial direction of the shaft member 351.

Next, a radio wave is transmitted from the probe antenna 30a and received by the calibration antenna 300. Based on the received radio wave received by the calibration antenna 300, the characteristics of each path including the data lines Sd1 and Sd2 connecting the probe antenna 30a and the network analyzer 70 are measured (step S3). Note that this path includes the data lines Sd3 and Sd4 connecting the calibration antenna 300 and the network analyzer 70, and further includes the probe antenna 30a itself.

Next, it is determined whether the measurement of the characteristics of the above-mentioned paths corresponding to all the probe antennas 30 is completed (step S4). If the measurement of the characteristics of all the paths is not completed (step S4: No), the process returns to step S2, and the calibration antenna 300 is rotated by the support jig 350 so that the calibration antenna 300 faces the next probe antenna 30. For example, if the calibration antenna 300 is in a position facing the probe antenna 30a, as shown in FIG. 17, the calibration antenna 300 is rotated by the support jig 350 so that the calibration antenna 300 faces the probe antenna 30b adjacent to the probe antenna 30a. Then, similar to the case of the probe antenna 30a, the characteristics of the path connecting the probe antenna 30b and the network analyzer 70 are measured (step S3). The order in which the characteristics of the paths are measured is not particularly limited, and the characteristics of the path corresponding to the probe antenna 30a may be measured after the characteristics of the path corresponding to the probe antenna 30c to 30o are measured.

Then, similar measurements are performed on the paths corresponding to each of the probe antennas 30c to 30o (step S3). When the characteristic measurements have been completed for all of the paths corresponding to the probe antennas 30a to 30o (step S4: Yes), the process proceeds to step S5, where the characteristic differences between the multiple paths are corrected based on the measurement results obtained in the above steps, i.e., the characteristics of each path, so that the characteristic differences between the paths are reduced. Note that the method for correcting the characteristic differences in step S5 can be any well-known method, so a detailed description of the correction method will be omitted.

The correction content (calibration data) of the characteristic difference may be stored in the memory unit 54 of the antenna characteristic measuring unit 50. When measuring the antenna 100 under measurement, the correction unit 524 corrects the transmission radio wave transmitted from the probe antenna 30 based on the calibration data stored in the memory unit 54. The output unit 53 outputs to the outside the transmission radio wave signal of the transmission radio wave corrected by the correction unit 524.

Performing the calibration process in this way makes it easier to measure the characteristics of each path.

Conventionally, the probe antenna cable was removed from the probe antenna and connected to the cable for the antenna under test, and after measuring the path characteristics, the probe antenna cable was removed from the cable for the antenna under test and reconnected to the probe antenna. This attachment and detachment procedure had to be performed a number of times corresponding to the number of probe antennas. Furthermore, when a probe antenna has a horizontally polarized antenna and a vertically polarized antenna and calibration processing is performed for both antennas, the above attachment and detachment procedure had to be performed twice as many times as the number of probe antennas, which required considerable effort and time.

However, in one embodiment, the calibration antenna 300 is opposed to each probe antenna 30 by the support jig 350 to measure the characteristics of each path, eliminating the need to detach and attach the cables as was previously done. This makes it possible to reduce the time required to perform the calibration process. Furthermore, by performing such a calibration process, the difference in characteristics of the paths including each probe antenna 30 can be kept relatively small. This improves the measurement accuracy (estimation accuracy) of the directivity of the antenna 100 by the antenna measurement device 10.

<Other embodiments>
The invention made by the inventor has been described in detail above based on one embodiment, but the present invention is not limited to the above embodiment. It goes without saying that the present invention can be modified in various ways without departing from the gist of the invention. In other words, the present invention allows the addition, deletion, or replacement of part of the configuration of the above embodiment with other configurations.

For example, in one embodiment, a configuration has been illustrated in which multiple probe antennas 30a-30o are arranged at equal intervals except between probe antennas 30a and 30o, and each of the probe antennas 30a-30o is connected to one another by a connecting portion 36, but the configuration of the probe antenna 30 is not limited to this. For example, the multiple probe antennas 30a-30o do not necessarily have to be arranged at equal intervals, and may be arranged at different intervals. In other words, the present invention can also be applied to an antenna measurement device equipped with multiple probe antennas arranged in a circular ring shape at different intervals.

Furthermore, the multiple probe antennas 30a to 30o do not all have to be integrated via the connecting portion 36. The multiple probe antennas 30a to 30o may be integrated by connecting multiple antennas at a time via the connecting portion 36. For example, the probe antennas 30a to 30e may be integrated via the connecting portion 36, the probe antennas 30f to 30j may be integrated via the connecting portion 36, and the probe antennas 30k to 30o may be integrated via the connecting portion 36. Even with such a configuration, it becomes easier to maintain the positional accuracy of each probe antenna 30 with high accuracy, and the installation time of the probe antennas 30 to the fixed panel 22 can be shortened.

Furthermore, the multiple probe antennas 30 do not necessarily have to be connected by the connecting portion 36. Also, as one embodiment, an example in which the multiple probe antennas 30 are arranged in a circular ring shape along the imaginary circle VC surrounding the antenna under test 100 has been described, but the arrangement of the multiple probe antennas 30 is not limited to this. Even if the multiple probe antennas 30 are not arranged in a circular ring shape, the measurement work time can be reduced by measuring the characteristics of each path using the calibration antenna 300.

Furthermore, as an example of a calibration method for the antenna measurement device 10, an example of performing the calibration process using the support jig 350 has been described, but the calibration method is not limited to this. The calibration process may be performed, for example, without using the support jig 350. In other words, as long as the calibration antenna 300 can be fixed facing each probe antenna 30, the support jig 350 does not need to be used. Furthermore, as one embodiment, an example has been described in which the antenna characteristic measuring unit 50 measures (estimates) directivity as a characteristic of the antenna 100, but the antenna characteristic measuring unit 50 may measure antenna characteristics other than directivity.

Furthermore, each of the configurations, functions, processing units, processing means, etc. of the antenna characteristic measuring unit 50 may be realized in hardware, for example, by designing some or all of them in an integrated circuit. Also, each of the configurations, functions, etc. described above may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a recording device such as a memory, hard disk, or SSD (Solid State Drive), or in a recording medium such as an IC card, SD card, or DVD. Furthermore, in the antenna measuring device 10, an antenna of a type different from the above-mentioned antenna 100 can also be used as the antenna to be measured.

10...antenna measuring device, 20...housing, 21...tunnel section, 22...fixing panel (fixing member), 23...penetration section, 24...notch section, 25...radio wave absorber, 30...probe antenna, 31h...horizontally polarized antenna, 31...antenna section, 31v...vertically polarized antenna, 32h...horizontally polarized board, 32v...vertically polarized board, 33h, 33v...coaxial cable, 34...support member, 35...fastening member, 36...connecting section, 37...connecting plate, 38...fixing member, 39...through hole, 40...positioner, 50...antenna characteristic measuring section, 60...switch timing control section, 70...network analyzer (measuring instrument), 80...positioner control section, 90...rail, 100...antenna (antenna to be measured), 200...mounting stand, 300: calibration antenna; 301: antenna part; 350: support jig; 351: shaft member; 352: shaft holding member; 353: base part; 354: support part; 355: clamp mechanism; 356: slit; 357: clamp lever

Claims (8)

A method for calibrating an antenna measurement device including a plurality of probe antennas and a measuring instrument to which an antenna under test is connected via a first cable and to which the plurality of probe antennas are respectively connected via individual second cables, comprising:
connecting the first cable to a calibration antenna and arranging the calibration antenna at positions corresponding to the plurality of probe antennas;
the calibration antenna is brought to face each of the probe antennas in sequence, and characteristics of each path including the second cable connecting each of the probe antennas to the measuring instrument are measured in sequence;
correcting characteristic differences of the plurality of paths based on the results of the measurements;
Calibration method. 2. The calibration method according to claim 1,
A plurality of the probe antennas are arranged in a circular ring shape along a virtual circle surrounding the antenna under test,
the calibration antenna is arranged at positions corresponding to the plurality of probe antennas and is rotatable about a center position of the imaginary circle as a rotation axis;
rotating the calibration antenna around the rotation axis to make the calibration antenna face each of the probe antennas in sequence;
Calibration method. 2. The calibration method according to claim 1,
the probe antenna has an antenna portion including a horizontally polarized antenna formed on a horizontally polarized substrate and a vertically polarized antenna formed on a vertically polarized substrate;
The calibration antenna has the same configuration as the antenna portion of the probe antenna.
Calibration method. A support jig for use in the calibration method according to claim 2,
a shaft member to which the calibration antenna is fixed;
a shaft holding member that holds the shaft member so that the calibration antenna rotates in a circumferential direction of the plurality of imaginary circles;
A base portion on which the shaft holding member is provided at a predetermined interval.
Support fixture. The support jig according to claim 4,
the shaft holding member includes a clamp mechanism capable of fixing the shaft member at a position where the calibration antenna faces the probe antenna;
Support fixture. An antenna measurement device comprising: a plurality of probe antennas; and a measuring instrument to which an antenna under test is connected via a first cable and to which the plurality of probe antennas are respectively connected via individual second cables,
The plurality of probe antennas are arranged in a circular ring shape along a virtual circle surrounding the antenna under test,
a calibration antenna to which the first cable is connected;
a support jig that supports the calibration antenna rotatably in a circumferential direction of the virtual circle,
Antenna measuring equipment. 7. The antenna measurement device according to claim 6,
The support jig is
a shaft member to which the calibration antenna is fixed;
a shaft holding member that holds the shaft member so that the calibration antenna rotates in a circumferential direction of the plurality of imaginary circles;
A base portion on which the shaft holding member is provided at a predetermined interval.
Antenna measuring equipment. 8. The antenna measurement device according to claim 7,
a positioner capable of executing an operation of linearly moving the antenna under test so as to pass through the inside of a plurality of the probe antennas arranged in a circular ring shape;
the positioner is configured to be capable of mounting the calibration antenna supported by the support jig in place of the antenna under test;
Antenna measuring equipment.

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