JP2001349917A - Apparatus for measuring radiation directivity of antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for measuring the radiation directivity of an antenna in which the antenna to be measured does not influence the radiated electromagnetic field even when the antenna is brought close to a super-vicinity area to the antenna to be measured. SOLUTION: In the apparatus for measuring the radiation directivity of an antenna to be measured which measures the two-dimensional electric field distribution or the interference complex data distribution as the two-dimensional magnetic distribution formed by the antenna to be measured to measure the radiation directivity of the antenna to be measured by the relative surface- scanning of the antenna to be measure and a probe antenna, the probe antenna is formed of a shielded loop antenna, and the radiation directivity can be measured without deforming the electromagnetic field to be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna radiation directivity measuring apparatus for measuring the radiation directivity of radio waves radiated from an antenna of a portable telephone or the like.

[0002]

2. Description of the Related Art In general, in order to measure the radiation directivity of an antenna, the distance between an antenna to be measured and a probe antenna is measured to be a distance called a far-field region. As the distance between the antenna to be measured and the probe antenna increases, the measurement is generally performed in an anechoic chamber because the distance from the antenna to the probe antenna is affected by the reflection from the surroundings. Therefore, an anechoic chamber having a relatively large space is required, and a large capital investment is required to measure the radiation directivity of the antenna.

In order to solve this inconvenience, the present applicant has proposed an electromagnetic wave measuring apparatus which measures an electromagnetic field distribution in a very near field and computes a radiation directivity in a far field by using Japanese Patent Application No. 10-107719. Proposed.

[0004]

In the measuring apparatus proposed above, an embodiment in which a loop antenna is used as a probe antenna has been described. However, when an electromagnetic field distribution in a very near-field region is simply measured using a loop antenna. It has been found that the loop antenna mainly responds to the magnetic field component, but also responds to the electric field component, so that an error occurs in the measurement result. In other words, the electromagnetic field distribution in the extremely near-field region is close to the wave source distribution, but when trying to measure this electromagnetic field, the electromagnetic field distribution is disturbed by the electric field coupling characteristics of the loop antenna, and the shape of the electromagnetic field distribution is faithfully determined. The inconvenience that measurement cannot be performed occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent electric field coupling between an antenna to be measured and a probe antenna,
Accordingly, it is an object of the present invention to provide an antenna radiation directivity measuring apparatus capable of measuring the radiation directivity of the antenna with high accuracy even if the probe antenna is arranged in the extremely near field region.

[0006]

According to a first aspect of the present invention, there is provided a surface scanning device for scanning a relative positional relationship between an antenna to be measured and a probe antenna in a plane, and an antenna for surface scanning by the surface scanning device. A scanning plane, a distance measuring device for measuring a distance between the other antenna, a reference antenna arranged at a fixed distance from the antenna to be measured, and interference complex data from signals induced by the probe antenna and the reference antenna. In a radiation directivity measurement device for an antenna configured to include an interference measurement device for measuring and a calculation display device for calculating and displaying the radiation directivity of the antenna to be measured based on the measurement result of the interference measurement device, a probe antenna is provided. We propose an antenna radiation directivity measurement device that uses a shielded loop antenna.

According to a second aspect of the present invention, a surface scanning device for scanning a relative positional relationship between an antenna to be measured and a probe antenna in a plane, a scanning surface of an antenna surface-scanned by the surface scanning device, and the other surface A distance measuring device that measures the distance to the antenna, a reference antenna placed at a fixed distance from the antenna to be measured, and the transfer characteristics between the antenna to be measured and the probe antenna measured from the signal induced by the probe antenna In the antenna radiation directivity measurement device including a network analyzer that performs calculation and a calculation display device that calculates and displays the radiation directivity of the antenna to be measured based on the measurement result of the network analyzer, the probe antenna has a shielded loop. We propose an antenna radiation directivity measuring device with an antenna.

[0008]

According to the present invention, since the electromagnetic field distribution of the electromagnetic wave radiated from the antenna to be measured is measured using the shielded loop antenna, the shielded loop antenna is not electrically coupled to the antenna to be measured. Therefore, the rate of disturbing the electromagnetic field radiated from the antenna under test can be reduced. As a result, there is an advantage that the shape of the electromagnetic field distribution in the extremely near-field region formed by the antenna to be measured can be measured more faithfully than when the loop antenna is simply used.

[0009]

FIG. 1 shows an embodiment of an antenna radiation directivity measuring apparatus according to the present invention. The radiation directivity measuring device for an antenna according to the present invention can be constituted by a surface scanning device 1, a control / recording / calculation / display device 2, an interference measuring device 3, and a level detector 4. The surface scanning device 1 includes an x-direction movable stage 1a and a y-direction movable stage 1b. In this example, the measured object is the measured antenna 5a. Mobile phone 5
Mounted while transmitting electromagnetic waves on the directional movable stage 1b, the y-directional movable stage 1b moves in minute steps in the y direction, and the x-directional movable stage 1a moves in minute steps in the x direction similarly. Perform surface operations. A rod LD protrudes from the x-direction movable stage 1a toward the y-direction movable stage 1b. The rod LD is supported by a structure in which the amount of protrusion can be freely set with respect to the x-direction movable stage 1a, and the distance h between the scanning surface of the probe antenna 1b attached to the tip of the rod LD and the antenna 5a to be measured.
Is freely changeable. The distance measuring device 1c measures the distance L from the antenna to be measured to the scanning surface of the probe antenna 1d. The rod LD is supported by a structure capable of changing the direction of penetration of the hole of the probe antenna 1d into the x direction and the y direction (φ direction). Control, recording and calculation
The display device 2 controls the direction of the rod LD together with the drive control of the surface scanning of the x-direction movable stage 1a and the y-direction movable stage 1b.

The interference measuring device 3 is disclosed in Japanese Unexamined Patent Publication No. 9-133721.
The outline of the device is a frequency converter 3A, 3B for converting the frequency of a signal induced by the probe antenna 1d and the reference antenna 6, and two frequency converters 3A, 3B. A multiplier 3C that multiplies the output and a detector 3D that detects the result of the multiplication are used. While the surface scanning device 1 performs surface scanning on the probe antenna 1d, a signal induced by the probe antenna 1d and the reference antenna 6 is used. Measure the interference complex data distribution. The measurement of the interference complex data is performed over a plurality of operation surfaces by changing the distance h.

A feature of the present invention is that the probe antenna 1d is a shielded loop antenna. FIG. 2 shows an example of the shielded loop antenna.
FIG. 2 shows an example in which a circular probe antenna is formed using a coaxial line. A loop having a radius a is constituted by a coaxial line 10 and a conductor (muk conductor) 11,
The core wire 12 of the coaxial line 10 is partially exposed, and the tip is connected to one end of the conductor 11. The other end of the conductor 11 is the coaxial line 1
0 is electrically connected to the outer conductor. With this structure, it responds only to the magnetic field without responding to the electric field. As a result, there is an advantage that the measurement can be performed faithfully while maintaining the original shape without deforming the electromagnetic field formed by the antenna under measurement.

FIG. 3 shows a modified example of the shielded loop antenna. In this example, a case is shown in which a conductor is formed on the printed circuit board 12 and a shielded loop antenna is formed by the conductor. 3A is a plan view, and FIG. B is a cross-sectional view taken along line CC shown in FIG. 3A. A conductive layer 13 is formed on a printed circuit board 12, and an insulating layer 14 is formed on an upper surface of the conductive layer 13.
Is formed, and the conductive line 15 is formed on the insulating layer 14. The conductive wire 15 is covered with an insulating layer 16 and the periphery of the insulating layer 16 is covered with a conductive layer 17 to obtain a coaxial structure. This coaxial structure is formed in a semi-loop shape, a gap G is formed at the tip, and the conductive wire 15 is slightly exposed in the gap G to form a sealed dead loop antenna of a printed circuit board.

By forming the shielded loop antenna on the printed circuit board 12 as described above, the portion of the gap G can be made even smaller, so that a shielded loop antenna having a small influence on the measured magnetic field distribution can be easily made. be able to. The following is Japanese Patent Application No. 10-1077.
The manner in which the radiation directivity of the antenna 5a to be measured is measured in the same manner as in the specification of No. 19 will be described in order. First, an antenna-integrated communication device equipped with the antenna to be measured 5a to be observed,
For example, the mobile phone 5 is placed in a talking state and placed on the y-direction movable stage 1b.

Next, the measured antenna 5a to be observed is
The reference antenna 6 is placed at a position where the relative positional relationship does not change (on the same y-direction movable stage 1b). In this state, the relative position between the probe antenna 1d and the antenna to be measured is surface-scanned by the surface scanning device 1, and the two-dimensional field distribution of the electromagnetic field radiated from the antenna 5a to be observed and the mobile phone housing 5b (electric field Or, the distribution of the interference complex data which is the distribution of the magnetic field) is measured. Because the field distribution is directional,
It is necessary to convert the direction of the probe antenna 1a into two directions of φ = 0 ° and φ = 90 °, and to measure each of them. That is,

[0015]

(Equation 1)

## EQU1 ## Simultaneously with or separately from the field distribution measurement, the mobile phone 5 to be observed and the probe antenna 1
The distance distribution H (x, y) between the two is measured using a distance measuring device 1c such as a laser displacement meter. Next, the first of the present invention
A data processing sequence of the electromagnetic wave measuring device of the antenna-integrated communication device according to the embodiment will be described with reference to FIG.

First, the distance distribution H (x, y) and the two-dimensional field distribution of the mobile phone 5 to be observed are obtained by moving the x-direction movable stage 1a and the y-direction movable stage 1b with the dxy step as the minimum movement unit. Complex data distribution

[0018]

(Equation 2)

Is measured and recorded (S1). Next, the height distribution H (x, y) and the interference complex data distribution

[0020]

(Equation 3)

Are superimposed and displayed (S2) (FIGS. 5 and 6). In FIGS. 5 and 6, the minimum movement unit: dxy = 3.9 mm Measurement range: 25 cm × 25 cm Measurement frequency: f = 2 GHz Wavelength of observation radio wave: λ = 15 cm Distance of probe antenna 1 d from measurement target: h =
Next, the cursor is moved on the monitor screen in a line area (for example, the linear antenna portion 5a of the mobile phone 5) and a surface area (for example, the housing 5b of the mobile phone 5) with respect to the display screen. It is designated by surrounding the target part (S3) (FIGS. 7 to 9). Next, the complex current distribution in the specified line region and surface region

[0022]

(Equation 4) Is the distance L (x, y) and the interference complex data distribution

[0023]

(Equation 5)

(S4). At this time, the relative distance between the probe antenna 1d and the measured antenna 5a is h,
Assuming that the distance distribution is H _(x , _y) and the probe antenna sensitivity at the measurement frequency is g _(f) , for example, the following calculation is performed. In the line area,

[0025]

(Equation 6) In the face area,

[0026]

(Equation 7) Other than the line area and the plane area,

[0027]

(Equation 8)

It is assumed that In the above equation (1), dxy · (h−HH
(X, y)) 2 is a weight for the line area, and in the above equation (2), (dxy) 2 · (h−H ((x, y))
Represents a weight for the surface region. Next, the distance distribution H (x, y) and the complex current distribution in the line region or the surface region

[0029]

(Equation 9) The directivity is obtained from (S5). For example, when λ is the wavelength of the observed radio wave, the horizontal component directivity in the horizontal plane is:

[0030]

(Equation 10) Vertical component directivity in horizontal plane:

[0031]

[Equation 11] Horizontal component directivity in vertical plane:

[0032]

(Equation 12) Vertical component directivity in vertical plane:

[0033]

(Equation 13) Is found. Next, the directivity of each component obtained above

[0034]

[Equation 14]

Is displayed (S6) (FIGS. 10 to 12).
In the first embodiment of the present invention, the surface scanning device 1 having the x-direction movable stage 1a and the y-direction movable stage 1b is used, but the x-direction, y-direction, h-direction, rotation direction φ, The present invention can be implemented as long as it is a movable surface scanning device.

[0036]

FIG. 13 shows a modified embodiment of the present invention. In this embodiment, a surface scanning device 1, a control / recording / calculation / display device 2, a network analyzer 7
It is composed of The x-direction movable stage 1a is provided with a distance measuring device 1c such as a laser displacement meter and a probe antenna 1d. If the object to be observed is operated by an external input, for example, the complex transfer is performed as in the antenna of FIG. Characteristic

[0037]

(Equation 15)

The network analyzer 7 may be used for the measurement. Also, in the modified embodiment of the present invention, x
Although the surface scanning device 1 having the directional movable stage 1a and the y-directional movable stage 1b is used, the x direction, the y direction, and the height h are used.
The present invention can be implemented as long as the probe scanner is movable in the direction and the rotation direction φ.

[0039]

As described above, according to the present invention, the shielded loop antenna shown in FIG. 2 or FIG. 3 is used as the probe antenna 1d. Only the response to the electric field and no response to the electric field, the degree of influence on the measured magnetic field distribution can be reduced. As a result, an advantage is obtained that the original shape can be faithfully measured without deforming the magnetic field distribution to be measured even when the probe antenna 1d is brought close to the extremely near field.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view for explaining an embodiment of the present invention.

FIG. 2 is a perspective view illustrating an example of a shielded loop antenna used in the present invention.

3A is a plan view and FIG. 3B is a cross-sectional view for explaining another example of the shielded loop antenna.

FIG. 4 is a perspective view for explaining the operation of the embodiment shown in FIG. 1;

FIG. 5 is a diagram in which a height distribution of a mobile phone and an interference complex data distribution which is a two-dimensional field distribution are superimposed and displayed.

FIG. 6 is a diagram in which a height distribution of a mobile phone and an interference complex data distribution which is a two-dimensional field distribution are superimposed and displayed.

FIG. 7 shows a line area (for example, a linear antenna of a mobile phone) and a surface area (for example, a housing of a mobile phone) with respect to a display screen.
FIG.

FIG. 8 is a diagram for designating only a line area (for example, a linear antenna of a mobile phone) on a display screen.

FIG. 9 is a diagram for designating only a surface area (for example, a housing of a mobile phone) with respect to a display screen.

FIG. 10 is a diagram illustrating a radiation directivity radar chart when a surface area (for example, a linear antenna of a mobile phone) and a surface area (for example, a housing of a mobile phone) are designated on a display screen.

FIG. 11 is a diagram showing a radiation directivity radar chart when only a line area (for example, a linear antenna of a mobile phone) is designated on a display screen.

FIG. 12 is a diagram showing a radiation directivity radar chart when only a surface area (for example, a casing of a mobile phone) is designated on a display screen.

FIG. 13 is a schematic perspective view of an antenna radiation directivity measuring apparatus proposed in claim 2 of the present invention.

[Explanation of symbols]

 Reference Signs List 1 surface scanning device 1a x-direction movable stage 1b y-direction movable stage 1c distance measuring device 1d probe antenna 2 control / recording / calculation / display device 3 interference measuring device 4 level detector 5 mobile phone 5a antenna under measurement 5b mobile phone housing 6 Reference antenna 7 Network analyzer

Claims (2)

[Claims] 1. A surface scanning device that scans a relative positional relationship between an antenna to be measured and a probe antenna in a plane, a scanning surface of an antenna surface-scanned by the surface scanning device, and the other antenna. A distance measuring device for measuring a distance between the antenna, a reference antenna disposed at a fixed distance from the antenna to be measured, an interference measuring device for measuring interference complex data from a signal induced by the probe antenna and the reference antenna, A calculation and display device for calculating and displaying the radiation directivity of the antenna to be measured based on the measurement result of the measuring instrument; and B, the probe antenna uses a shielded loop antenna. A radiation directivity measuring device for an antenna, wherein the radiation directivity measuring device comprises: 2. A surface scanning device for scanning the relative positional relationship between an antenna to be measured and a probe antenna in a plane, a scanning surface of an antenna surface-scanned by the surface scanning device, and the other antenna. A distance measuring device for measuring a distance between the antenna to be measured, a reference antenna arranged at a fixed distance from the antenna to be measured, and a transfer characteristic between the antenna to be measured and the probe antenna measured from a signal induced by the probe antenna. In a radiation directivity measuring apparatus for an antenna, comprising: a network analyzer; and a calculation and display device for calculating and displaying the radiation directivity of the antenna to be measured based on the measurement result of the network analyzer, B, the probe antenna is sealed. An antenna radiation directivity measuring apparatus, characterized in that it has a configuration using a dead loop antenna.