WO2003098239A1

WO2003098239A1 - Electromagnetic irradiation distribution measurement device

Info

Publication number: WO2003098239A1
Application number: PCT/JP2003/005849
Authority: WO
Inventors: Yutaka Saito; Yoshio Koyanagi; Koichi Ogawa; Shoichi Kajiwara; Akihiro Ozaki; Yoshitaka Asayama
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2002-05-17
Filing date: 2003-05-09
Publication date: 2003-11-27
Also published as: CN100514073C; CN1666108A; JP4112898B2; JP2003337152A; CZ20041123A3; AU2003235923A1

Abstract

It is possible to measure a neighboring electromagnetic field distribution irradiated from a small-size radio communication device such as a mobile telephone with a high accuracy at a high speed. An electromagnetic irradiation distribution measurement device includes a plurality of U-shaped loop elements (1a to 1n) mounted at a predetermined interval on a printed circuit board (2), a holding substrate (5) having on its lower surface an electromagnetic wave absorption sheet (6), and level detection sections (7a to 7n) to which the loop elements (1a to 1n) are connected via coaxial cables (4a to 4n) fixed to the holding substrate (5). Neighboring electromagnetic field signals detected by the loop elements (1a to 1n) are converted into DC voltage signals (11a to 11n) in the level detection sections (7a to 7n) and output. The signals are converted into digital data by an AD converter (15) and the measurement data on the neighboring electromagnetic field level obtained by detection of a magnetic field component is stored in a processing section (16).

Description

Description Electromagnetic radiation distribution measuring device <Technical field>

The present invention relates to an apparatus for measuring electromagnetic radiation characteristics, and more particularly to an electromagnetic radiation distribution measuring apparatus for measuring a near electromagnetic field distribution radiated from a wireless communication device such as a mobile phone. <Background technology>

In general, in a wireless communication device such as a mobile phone, it is important for the design of the device and EMC measures to know the nearby electromagnetic field distribution that indicates the intensity of the electromagnetic wave emitted from which part of the device. . 2. Description of the Related Art Conventionally, as a device for measuring a near electromagnetic field distribution, for example, a device disclosed in Japanese Patent Application Laid-Open No. Sho 62-237363 is known. This apparatus is a sequential selection type measuring apparatus in which about 100 micro loop elements are arranged in a grid in a plane, and the detected signals are sequentially selected by a switching diode.

Also, Japanese Patent Application Laid-Open No. 9-304456 discloses a configuration in which a plurality of antenna elements arranged in a row and a frequency selection level detection circuit are connected to each other, and the detected signals are stored simultaneously. A parallel detection type measuring device for processing is disclosed. According to this, it is possible to measure the planar distribution of the near electromagnetic field by moving a plurality of antenna elements in a predetermined direction.

However, the conventional sequential-selection-type measuring device described above sequentially selects and measures about 100,000 micro loop elements, so that it takes a lot of time to complete all the measurements. There was a problem. In addition, due to the capacitance between the terminals of the switching diode and the frequency characteristics of the transmission line, the detection sensitivity decreases and the isolation between adjacent small loop elements deteriorates, especially in a high frequency band, for example, the 2 GHz band. There was a point.

In the conventional parallel detection type measuring device, detection signals from a plurality of antenna elements are used. The advantage is that the measurement time is short because the processing is performed in parallel, but no consideration has been given to the measurement of DUTs with small and complex shapes such as mobile phones. Furthermore, when measuring near-level electromagnetic fields at a high level radiated from an antenna of a wireless communication device such as a mobile phone, there is a problem between the antenna element and the level detection unit and between the wireless communication device and the frequency selection level. Electromagnetic shielding between the detector and the circuit was not sufficiently considered.

In addition, the above two conventional measuring devices set a level detection frequency necessary for measuring an electromagnetic field near the transmission frequency when a wireless communication device such as a mobile phone performs a transmitting operation, No consideration was given to measurement during intermittent transmission. Furthermore, no measures have been taken to improve the measurement accuracy by correcting the variation in detection sensitivity of each minute loop element or antenna element and the variation in circuit characteristics in the level detection unit or the frequency selection level detection circuit.

In addition, these conventional measuring devices are premised on measuring near-field electromagnetic fields having a relatively low frequency of 1 GHz or less leaking from a flat device under test such as an electronic circuit board. In the measurement of near-field electromagnetic fields at high frequencies such as the 2 GHz band, the isolation between small loop elements and antenna elements was not sufficient.

The present invention has been made in view of the above circumstances, and an object of the present invention is to measure a nearby electromagnetic field distribution radiated from a small wireless communication device such as a mobile phone with high speed and high accuracy. An object of the present invention is to provide an electromagnetic radiation distribution measuring device.

An electromagnetic radiation distribution measuring device according to the present invention is an electromagnetic radiation distribution measuring device that measures a near electromagnetic field distribution radiated from a wireless communication device, and is arranged in a row to reduce an electromagnetic field radiated from the wireless communication device. A plurality of electromagnetic field detecting means for outputting a corresponding electric signal; and a level detecting means for detecting a level of an electric signal obtained by each of the plurality of electromagnetic field detecting means, which is connected correspondingly to each of the plurality of electromagnetic field detecting means. An electromagnetic shielding unit disposed between the electromagnetic field detection unit and the wireless communication device and the level detection unit; and a relative position on a measurement surface between the electromagnetic field detection unit and the wireless communication device. Change A moving means; and an arithmetic processing means for storing and processing the electromagnetic field level, which is a detection result of the level detecting means, and the relative position in association with each other. According to the above configuration, it is possible to measure a high-level near-field distribution radiated from a wireless communication device such as a mobile phone at high speed and with high accuracy.

Further, the plurality of electromagnetic field detecting means has a printed circuit board on which a plurality of loop elements formed by forming conductors in a loop shape are arranged in a row, and the printed circuit board has one-to-one correspondence with the plurality of loop elements. And a plurality of ground patterns each connected to one end of the loop element.

With this configuration, it is possible to prevent the isolation (electromagnetic shielding) from deteriorating due to the electromagnetic coupling of each loop element constituting the electromagnetic field detecting means, and to measure the high frequency near electromagnetic field radiated from the wireless communication device. Accuracy can be improved.

Further, the electromagnetic shielding means is configured by an electromagnetic wave absorber provided on one surface of a holding substrate that holds the plurality of electromagnetic field detecting means. With this configuration, the isolation between the plurality of electromagnetic field detecting means and the level detecting means is improved, and the detection accuracy of the near electromagnetic field is enhanced.

Further, in the plurality of electromagnetic field detecting means, an electromagnetic shielding means is provided between the adjacent loop elements. With this configuration, the isolation between the loop elements constituting the electromagnetic field detecting means is improved, and the near-field distribution of a high frequency radiated from the wireless communication device can be accurately measured.

The apparatus further includes a local oscillation unit that generates a local oscillation signal, wherein the level detection unit detects an electromagnetic field level at a specific frequency by mixing the electric signal obtained by the electromagnetic field detection unit with the local oscillation signal. It is characterized by doing.

With this configuration, it is possible to measure the near-field distribution at an arbitrary frequency corresponding to the transmission frequency radiated from the wireless communication device at high speed and with high accuracy.

The wireless communication apparatus further includes control means for controlling a measurement operation in accordance with a transmission operation of the wireless communication apparatus, wherein the arithmetic processing means performs an intermittent transmission operation of the wireless communication apparatus based on control of the control means. In this case, the electromagnetic field level detected by the level detection means is stored in synchronization with the transmission timing.

With this configuration, the near-field radiated from the wireless device that is performing intermittent transmission can be obtained. The near electromagnetic field distribution can be measured with high accuracy.

Also, the arithmetic processing means integrates or averages the electromagnetic field level detected by the level detection means during a detection period corresponding to a predetermined number of intermittent transmission operations of the wireless communication device, and stores the integrated electromagnetic field level. It is characterized by the following.

With this configuration, it is possible to accurately measure the near-field distribution radiated from the wireless device that is performing intermittent transmission.

A plurality of measurement systems including the plurality of electromagnetic field detection units and the level detection unit; and a correction data obtaining unit for obtaining the detection sensitivity of each of the measurement systems and obtaining correction data. A correction means for correcting an electromagnetic field level as a detection result of the means by the correction data.

With this configuration, the correction data based on the characteristics of the individual measurement systems is obtained in advance, and the detected electromagnetic field level is corrected using the correction data, so that the measurement accuracy of the near electromagnetic field distribution radiated from the wireless communication device is measured. Can be improved.

Further, the correction data obtaining means includes: a reference signal generating means for generating a reference signal having a variable frequency; and a reference electromagnetic field based on the reference signal, which is arranged corresponding to each of the plurality of electromagnetic field detecting means. The arithmetic processing means stores detection levels of the plurality of measurement systems and the reference electromagnetic field in each of the plurality of measurement systems in association with a frequency.

With this configuration, the frequency characteristic of each measurement system is obtained, and the electromagnetic field level detected by the correction data based on the frequency characteristic is corrected, so that the near electromagnetic field is adjusted in accordance with the transmission frequency radiated from the wireless communication device. It is possible to improve the distribution measurement accuracy.

FIG. 1 is an explanatory diagram showing a configuration of an electromagnetic radiation distribution measuring device according to a first embodiment of the present invention, (a) is a front view, (b) is a side view,

FIG. 2 is a configuration diagram of an electromagnetic wave absorber that electromagnetically shields loop elements that can be arranged in the electromagnetic radiation distribution measuring device of the present embodiment,

FIG. 3 is a side view showing the configuration of the electromagnetic radiation distribution measuring device according to the second embodiment of the present invention. FIG.

FIG. 4 is an evening timing chart showing a measurement operation associated with intermittent transmission of a mobile phone in the second embodiment.

FIG. 5 is an explanatory diagram showing a configuration of an electromagnetic radiation distribution measuring device according to a third embodiment of the present invention, wherein (a) is a front view, (b) is a side view,

FIG. 6 is an explanatory diagram showing detection level frequency characteristic data obtained in the third embodiment.

The symbols in the figure, la to ln are loop elements, 2 is a printed circuit board, 3 a to 3 n is a ground pattern, 5 is a holding board, 6, 40 a to 40 n are electromagnetic wave absorbing sheets, 7 a to 7 n Is a level detector, 8a to 8n is a mixer, 9a to 9n is a bandpass filter, 10a to: L0n is a logarithmic detector, 11a to 11n is a DC voltage signal, 1 2 a to l 2 n are local oscillation signals, 13 is a distributor, 14 is a local oscillator, 15 is an AD converter, 16 is an arithmetic processing unit, 17 is a mobile phone, 18 is a movable base, 2 2 Is a control unit, 28 a to 28 n is a strip line, 29 is a ground pattern, 30 a to 30 n is a termination resistor, 31 is a reference signal source, 32 is a distribution circuit, 33 a to 33 n is a detection level frequency Characteristic de overnight. BEST MODE FOR CARRYING OUT THE INVENTION>

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment)

FIG. 1 is an explanatory view showing a configuration of an electromagnetic radiation distribution measuring device according to a first embodiment of the present invention, where FIG. 1 (a) is a front view and FIG. 1 (b) is a side view. The electromagnetic radiation distribution measuring device consists of n loop elements 1 a to 1 n, coaxial cables 4 a to 4 n, level detectors 7 a to 7 n, holding board 5, distributor 13 and local It comprises an oscillator 14, an AD converter 15 and an arithmetic processing unit 16. Then, a near electromagnetic field distribution radiated from the mobile phone 17 mounted on the movable base 18 arranged above the loop elements 1a to 1n is measured. Here, the number n of the measurement systems including the loop elements 1 a to 1 n and the level detection units 7 a to 7 n is, for example, 9 or the like, and generally around 10 is selected. The loop elements 1a to 1n corresponding to the electromagnetic field detecting means are formed by shaping a copper wire having a diameter of, for example, 0.5 mm into a U-shape having a side of 3 mm. Then, they are mounted in one row so that each loop surface is parallel and perpendicular to the printed circuit board 2. The interval between the loop elements 1a to In is set to, for example, 5 mm.

One end of each of the loop elements 1 a to 1 n is connected to a corresponding one of the ground patterns 3 a to 3 n which are printed and wired independently on the printed circuit board 2, and the other end is a coaxial line constituting a transmission line. Each of the cables 4a to 4n is connected to the center conductor. The outer conductors of the coaxial cables 4a to 4n are connected to the ground patterns 3a to 3n, respectively.

The coaxial cables 4a to 4n penetrate the holding substrate 5 and are fixed by fixing means such as bonding, so that the printed circuit board 2 on which the loop elements 1a to 1n are mounted is coaxial cable 3a to It is held by the holding substrate 5 via 3 n.

The holding substrate 5 is formed of a non-magnetic member, for example, a resin plate of 5 mm thick acrylic or the like so as not to affect the nearby electromagnetic field radiated from the mobile phone 17. On the lower surface of the holding substrate 5, an electromagnetic wave absorbing sheet 6 for absorbing and attenuating electromagnetic waves, which is equivalent to an electromagnetic shielding means made of, for example, a ferrite-based / alloy-based magnetic material, is attached. Electromagnetic shielding between 1 a to ln and the level detectors 7 a to 7 n is achieved.

The level detection units 7a to 7n corresponding to the level detection means include mixers 8a to 8n, band-pass filters 9a to 9n, and logarithmic detectors 10a to 10n. Detects the level of a specific frequency component of the electromagnetic field by the loop elements 1a to 1n input through the coaxial cables 4a to 4n, converts the level into a DC voltage signal 1la to 1In, and outputs the signal.

The mixers 8a to 8n mix the electromagnetic field signal of a specific frequency detected by the minute loop element with the local oscillation signals 12a to l2n and convert it to an intermediate frequency signal having a frequency corresponding to the difference between the two signals. I do. For example, when the transmission frequency of the mobile phone 17 is 2000 MHz, by setting the frequency of the local oscillation signals 12a to 12n to 220 MHZ, n intermediate frequency signals having a frequency of 200 MHz can be obtained.

The bandpass filters 9a to 9n are, for example, S AW filters and ceramic filters. And the like, and passes the intermediate frequency signal with a predetermined bandwidth. The logarithmic detectors 10a to 10n are generally composed of logarithmic output type multistage amplifiers, and have a DC voltage signal 11a to 11n that has a linear level with respect to the decibel value of the intermediate frequency signal. Is output. The distributor 13 outputs the local oscillation signals input from the local oscillator (local oscillation means) 14 as local oscillation signals 12 a to l 2 n of the same level, and distributes them to the mixers 8 a to 8 n It is. The local oscillator 14 is a circuit that generates a local oscillation signal ′ necessary for generating n intermediate frequency signals in the mixers 8 a to 8 n, and the oscillation frequency is the frequency of the electromagnetic field to be measured. Therefore, it is set higher by the frequency of the intermediate frequency signal.

The AD converter 15 is controlled by the arithmetic processing unit 16 and converts the n-system DC voltage signals 1 la to l 1 n, which are analog signals, into digital data in parallel. The arithmetic processing unit 16 corresponding to the arithmetic processing means inputs and stores the digital data of the electromagnetic field signal level, performs arithmetic processing on the input digital data, and outputs the measurement results to an external monitor or printer. Output to an output device such as evening.

On the upper part of the holding substrate 5, as a moving means, a movable base 18 for supporting a mobile phone 17, which is an object to be measured, supported by four wheels 19 is installed. The movable table 18 is made of a non-magnetic material, for example, acrylic resin, so as not to affect a nearby electromagnetic field radiated from the mobile phone 17, and is mounted on the holding substrate 5 via wheels 19. You can move in the X direction in the figure.

Next, the operation of the electromagnetic radiation distribution measuring device of the present embodiment configured as described above will be described. Here, a case is described in which an electromagnetic field of a specific frequency radiated from the mobile phone 17 as the device under test is measured. However, when an electromagnetic field of an arbitrary frequency is measured, the local oscillator 1 The operation described below is repeated while controlling and setting the oscillation frequency of 4, for example, by the arithmetic processing unit 16.

The loop elements l a to l n operate as a loop antenna that generates an induced voltage mainly due to the magnetic field in the Y direction among the near electromagnetic fields radiated from the mobile phone 17 mounted on the movable base 18.

The detected magnetic field signal is input to the level detectors 7a to 7n via the coaxial cables 4a to 4n, and the detection level of the magnetic field component at each position of the loop elements 1a to 1n Are output. Next, the DC voltage signals 11 a to 1 In are converted into digital data in the AD converter 15 and stored in the arithmetic processing unit 16. Here, the obtained digital data is a nearby electromagnetic field distribution in the Y direction of the mobile phone 17 in a state where the movable base 18 is fixed at the predetermined position X1 in the X direction. The resolution of the electromagnetic field detection is determined by the arrangement interval of the loop elements 1a to ln, and is, for example, 5 mm.

Next, the movable table 18 is moved in the X direction by a predetermined distance, for example, 5 mm. Then, digital data indicating the detection level of the magnetic field component at the position of X2 of the mobile phone 17 is acquired in the same procedure as described above, and stored in the arithmetic processing unit 16. Hereinafter, by repeating such an operation m times, a distribution diagram of a nearby electromagnetic field composed of m × n points arranged two-dimensionally is obtained. For example, a measurement system including nine loop elements and a level detector is provided, and the near field is measured at nine locations while moving the movable table 18. Is obtained.

As described above, in the present embodiment, a plurality of loop elements 1 a to 1 n arranged in a line at a predetermined interval detect a nearby electromagnetic field level at each point in the Y direction, and convert this to digital data. Then, the data is stored in parallel in the arithmetic processing unit 16 and this operation is repeated m times. This makes it possible to measure the near-field distribution radiated from the mobile phone 17 at high speed.

Here, when the level of the electromagnetic wave radiated from the mobile phone 17 is high and leaks directly to the circuits of the level detectors 7a to 7n, this becomes noise and the S / N (signal to noise However, in this embodiment, the electromagnetic wave absorbing sheet 6 is attached to the lower surface of the holding substrate 5, so that the electromagnetic wave radiated from the mobile phone 17 due to the electromagnetic shielding effect of the electromagnetic wave absorbing sheet 6 is reduced. Effective shielding can be achieved, and leakage of electromagnetic waves to the level detectors 7a to 7n can be prevented. As a result, the S / N in the measurement of the near electromagnetic radiation distribution is improved, and the measurement accuracy can be increased. In addition, the printed circuit board 2 is provided with ground patterns 3a to 3n independently for each of the loop elements 1a to 1n, and the other ends of the loop elements 1a to 1n and the coaxial cable 4a. ~ 4n external conductors are connected to the ground patterns 3a ~ 3n correspondingly, so isolation by electromagnetic coupling of each loop element and signal line (Electromagnetic shielding) can be prevented from deteriorating, and measurement accuracy can be improved.

As a modification of the configuration of the loop element of the present embodiment, as shown in FIG. 2, in order to enhance the electromagnetic shielding effect between the loop elements 1a to ln, an electromagnetic Electromagnetic wave absorbing sheets 40a to 40n may be provided as shielding means. Each of the electromagnetic wave absorbing sheets 40a to 40n has a layered structure, and the metal plate 42 is formed by two magnetic thin films 41 having a thickness of about 0.5 mm that absorb and attenuate electromagnetic waves. It is sandwiched between them. The electromagnetic wave absorbing sheets 40a to 40n are arranged between two adjacent loop elements. As a result, the electromagnetic coupling between adjacent loop elements can be weakened, so that the isolation can be increased and the positional resolution when measuring the near electromagnetic field distribution can be improved.

The electromagnetic shielding means interposed between the loop elements 1a to ln may be a fixed electromagnetic wave absorber such as a magnetic body or a conductor plate such as a metal plate. The effect is obtained. For this reason, the electromagnetic wave absorbing sheet 40 a to 40 n between the loop elements 1 a to 1 n and the electromagnetic wave absorption provided on the lower surface of the holding substrate 5 are provided within a range that does not affect the nearby electromagnetic field radiated by the mobile phone 17. The sheet 6 and the like can be formed at low cost using only the electromagnetic wave absorber or only the conductor plate.

The configuration and dimensions of the loop elements 1a to 1n are not limited to those of the present embodiment. For example, a shielded loop antenna may be used, and the dimensions are large enough to secure a desired detection sensitivity at a measurement frequency. That's fine.

Further, the loop element shown in the present embodiment mainly detects a magnetic field component. However, by using a micro dipole element or a micro monopole element, it is possible to mainly measure an electric field component.

Further, in the present embodiment, the mobile phone 18 is manually moved, and the mobile phone 17 placed on the mobile board 18 is two-dimensionally scanned to measure the electromagnetic radiation distribution. A driving means such as a stepping motor may be used as the moving means 8 and the movable table 18 may be driven by operating under the control of the arithmetic processing unit 16. As a result, the measurement operation can be automated, and the near-field distribution radiated from the mobile phone 17 can be measured at higher speed. (Second embodiment)

FIG. 3 is a side view showing the configuration of the electromagnetic radiation distribution measuring device according to the second embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. In general, in mobile phones, intermittent transmission is performed to cut the transmission radio wave when there is no transmission voice in order to extend the talkable time by minimizing battery consumption. Therefore, when measuring the near electromagnetic field radiated from the mobile phone, it is desirable that the intermittent transmission state be set according to the actual use. In view of this, the present embodiment shows a configuration of an electromagnetic radiation distribution measuring device that measures a near electromagnetic field in a mobile phone in an intermittent transmission state.

The electromagnetic radiation distribution measuring device according to the second embodiment includes a control unit 22 that controls a measuring operation. The connector 20 is a connection terminal for inputting a control signal for externally controlling the operation of the mobile phone 17. The control unit 22 generates a control signal 23 consisting of a pulse train output at a predetermined cycle (four times in the figure) intermittent transmission timing at a predetermined cycle as shown in FIG. 4 (a). Then, the control signal 23 is output to the mobile phone 17 via the cable 21 connected to the connector 20, and is similarly output to the arithmetic processing unit 16 via the cable 24.

The mobile phone 17 performs the transmission operation during the high voltage level period (H period) of the control signal 23 shown in FIG. As a result, the transmission power 24 of the mobile phone 17 becomes high in synchronization with the H period as shown in FIG. 4 (b). '

The loop elements l a to l n detect the level of the near electromagnetic field radiated with the transmission of the mobile phone 17, and output DC voltage signals 1 l a to l 1 n in the level detectors 7 a to 7 n. Then, the AD converter 15 converts the DC voltage signals 11a to l1n into digital data.

The arithmetic processing unit 16 inputs the digital data of the detected near electromagnetic field level in synchronization with the H period of the control signal 25 as shown in FIG. 4 (c), and stores it in an internal memory. In addition, the arithmetic processing unit 16 receives the digitized data of the near electromagnetic field level and stores the near electromagnetic field level 26 integrated or averaged over a predetermined period as shown in FIG. 4D. As a result, when the mobile phone 17 is performing the intermittent transmission operation Then, a value obtained by integrating or averaging the transmission power within a predetermined period is obtained.

As described above, according to the present embodiment, in a state where the mobile phone 17 is performing the intermittent transmission operation, the vicinity electromagnetic field distribution can be accurately measured during a period in which a predetermined transmission power is obtained.

In this embodiment, the control unit 22 is configured to control the intermittent transmission of the mobile phone 17 and the processing and storage of the detection data in the arithmetic processing unit 16. The same effect can be obtained by detecting the intermittent transmission timing by the control unit 22 and generating a control signal based on this to control the processing and storage operations of the arithmetic processing unit 16.

(Third embodiment)

FIG. 5 is an explanatory view showing a configuration of an electromagnetic radiation distribution measuring device according to a third embodiment of the present invention. FIG. 5 (a) is a front view, and FIG. 5 (b) is a side view. The same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

The detection sensitivity of the loop elements la to ln generally varies depending on the dimensional accuracy during processing. In addition, the characteristics of the circuit components constituting the level detectors 7a to 7n are not always the same, and the detection sensitivity varies and the frequency characteristics also change. Thus, the third embodiment shows an example in which the electromagnetic radiation distribution measurement device described in the first and second embodiments has a measurement data calibration function for calibrating detection sensitivity and frequency characteristics.

In FIG. 5, a printed circuit board 27 constituting the correction data acquisition means is arranged at the position of the mobile phone above the loop elements 1 a to ln. On the printed circuit board 27, strip lines 28a to 28n corresponding to electromagnetic field generating means are formed on the lower surface, and ground patterns 29 are formed on the upper surface by printing or the like, and wired. One end of each strip line 28a to 28n is terminated by a termination resistor 30a to 30n equal to the characteristic impedance (generally 50Ω), and the other end is a reference signal source (reference signal generation means). It is connected to the distribution circuit 32 to which the output signal of 31 is supplied.

The positions of the strip lines 28 a to 28 n in the Y direction are arranged so as to face the loop elements 1 a to 1 n, respectively. As a result, the stripline 28 a ~ 28 Near-fields emitted from n are detected by the loop elements 1a to ln, respectively. ,

Next, a measurement calibration operation in the electromagnetic radiation distribution measuring device of the present embodiment configured as described above will be described. Here, an example in which the measurement operation is applied to the first embodiment will be described.

First, a reference signal of a predetermined frequency is supplied from the reference signal source 31 to the distribution circuit 32. The distribution circuit 32 distributes the reference signal to the strip lines 28a to 28n. As a result, the strip lines 28a to 28n each emit an electromagnetic field based on the reference signal. The loop element 1 _a ~ 1 n, is constant with electromagnetic radiation of the already known are excited from the string Uz flop line 2 8 a~ 2 8 n, the electromagnetic field is detected by the excitation. Then, in the same manner as described in the first embodiment, the detection levels of the loop elements 1 a to 1 n are converted into digital data and stored in the arithmetic processing unit 16. In the present embodiment, the frequency of the reference signal output from the reference signal source 31 is changed from f1 to f2, and the change in the near electromagnetic field detection level at this time is detected and stored in the arithmetic processing unit 16 .

That is, the reference signal source 31 generates a reference signal by changing the frequency from f 1 to f 2 while changing the frequency from f 1, and detects the level of the near electromagnetic field at each frequency for each of the loop elements 1 a to 1 n. Perform the measurement. Then, all of the detection levels are stored in the arithmetic processing device 16 in the form of digital data. As a result, the arithmetic processing unit 16 obtains the frequency characteristic data 33 a to 33 n of the near electromagnetic field detection level as shown in FIG. 6, and stores this.

When actually measuring the electromagnetic field near the mobile phone 17 as the device under test, the detection level frequency characteristic data 33 a to 33 n obtained as described above is used to The digital data of the measurement result is corrected. This makes it possible to calibrate the variation in detection sensitivity due to the frequency in a plurality of systems.

As described above, in the present embodiment, the frequency characteristics of the detection sensitivity of each of the measurement systems of the loop elements 1 a to 1 n and the level detection units 7 a to 7 n are converted into the reference signal source 3 1 capable of generating a frequency-variable reference signal. And can be stored in the arithmetic processing unit 16 as the detection level frequency characteristic data 33 a to 33 η. When measuring the electromagnetic field distribution in the vicinity of the mobile phone using the electromagnetic radiation distribution measuring device, By correcting with the numerical characteristic data 33a to 33n, the device can be calibrated, and the accuracy of the measurement is remarkably improved.

In this embodiment, the strip lines 28 a to 28 n which are excited by the reference signal generated by the reference signal source 31 are used as a means for generating the near-field electromagnetic field serving as a reference. A reference antenna such as a pole or a loop may be used. Alternatively, a mobile phone whose nearby electromagnetic field is known by measurement in advance may be used. According to the above-described embodiment, the near-field distribution radiated from a small wireless communication device such as a mobile phone can be measured at high speed and with high accuracy. In addition, it is possible to accurately measure the distribution of a nearby electromagnetic field radiated from a wireless communication device that is performing intermittent transmission such as a mobile phone. In addition, a measurement data calibration function is provided, and the frequency characteristic data of the detection level of the electromagnetic field is acquired in advance and used for calibration, so that the measured data can be accurately compensated for the actual measurement of the nearby electromagnetic field distribution. Can be corrected. Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2002-143327 filed on May 17, 2002, the contents of which are incorporated herein by reference.

As described above, according to the present invention, there is provided an electromagnetic radiation distribution measuring device capable of measuring a near electromagnetic field distribution radiated from a small wireless communication device such as a mobile phone at high speed and with high accuracy. it can.

Claims

The scope of the claims

1. An electromagnetic radiation distribution measuring device for measuring a near electromagnetic field distribution radiated from a wireless communication device,

A plurality of electromagnetic field detecting means arranged in a row and outputting an electric signal corresponding to an electromagnetic field radiated from the wireless communication device;

Level detecting means for detecting the level of an electric signal obtained by each of the plurality of electromagnetic field detecting means, the level detecting means being connected corresponding to that of the plurality of electromagnetic field detecting means;

Electromagnetic shielding means disposed between the electromagnetic field detecting means and the wireless communication device and the level detecting means,

Moving means for changing a relative position of the electromagnetic field detecting means and the wireless communication device on a measurement surface;

Arithmetic processing means for storing and processing an electromagnetic field level as a detection result of the level detection means and the relative position in association with each other;

An electromagnetic radiation distribution measuring device comprising:

2. The plurality of electromagnetic field detecting means includes a printed circuit board on which a plurality of loop elements each formed by forming a conductor in a loop shape are mounted in a row, and the printed circuit board corresponds to the plurality of loop elements in a one-to-one correspondence. 2. The electromagnetic radiation distribution measuring device according to claim 1, wherein one end of the loop element is provided with a plurality of ground patterns connected to the loop element.

3. The electromagnetic shielding device according to claim 1, wherein the electromagnetic shielding unit is configured by an electromagnetic wave absorber provided on one surface of a holding substrate that holds the plurality of electromagnetic field detecting units. The electromagnetic radiation distribution measuring device according to the above.

4. The electromagnetic radiation distribution measuring device according to claim 2, wherein in the plurality of electromagnetic field detecting means, an electromagnetic shielding means is provided between the adjacent loop elements.

5. A local oscillation means for generating a local oscillation signal is provided.

2. The level detector according to claim 1, wherein the level detector detects an electromagnetic field level at a specific frequency by mixing the electric signal obtained by the electromagnetic field detector with the local oscillation signal. Electromagnetic radiation distribution measuring device.

6. A control unit that controls a measurement operation according to a transmission operation of the wireless communication device,

The arithmetic processing means stores an electromagnetic field level detected by the level detection means in synchronization with a transmission timing when the wireless communication device is performing an intermittent transmission operation based on the control of the control means. 2. The electromagnetic radiation distribution measuring device according to claim 1, wherein:

7. The arithmetic processing means integrates or averages and stores the electromagnetic field level detected by the level detection means during a detection period corresponding to a predetermined number of intermittent transmission operations of the wireless communication device. The electromagnetic radiation distribution measuring device according to claim 6, wherein:

8. A plurality of measurement systems including the plurality of electromagnetic field detection means and the level detection means, and a correction data acquisition means for acquiring detection sensitivity of each of the measurement systems and obtaining correction data, wherein the arithmetic processing means comprises: 2. The electromagnetic radiation distribution measuring device according to claim 1, further comprising a correction unit that corrects an electromagnetic field level detected by the detection unit with the correction data.

9. The correction data obtaining means includes: a reference signal generating means for generating a reference signal having a variable frequency; and a reference electromagnetic field based on the reference signal, which is arranged corresponding to each of the plurality of electromagnetic field detecting means. Electromagnetic field generating means to perform,

The method according to claim 1, wherein the arithmetic processing means stores a detection level of the plurality of measurement systems with respect to the reference electromagnetic field in association with a frequency. Electromagnetic radiation distribution measurement device described in section (