JP5008713B2 - Apparatus and method for measuring radiated power - Google Patents

Description

  The present invention belongs to the technical field of mobile communication, and particularly relates to an apparatus and method for determining weights for a plurality of transmission antenna elements provided in a mobile terminal. The present invention also relates to an apparatus and method for measuring power radiated from a wireless terminal.

  In the design of a mobile terminal represented by a mobile phone, improving transmission efficiency during wireless transmission is one of the important concerns. This is because a part of the transmission power is lost due to the human body or other objects in the vicinity of the mobile terminal, and the transmission efficiency is lowered. The cause of reducing the transmission efficiency is not limited to the human body, but may be any object that hinders radio wave propagation.

  On the other hand, it is known that the transmission efficiency is improved by simultaneously feeding a plurality of antenna elements whose amplitudes and phases are appropriately adjusted and adjusting the direction of transmission radio waves. The relative amplitude ratios and phase differences between the antenna elements are referred to as weights, weights, feed weights, and the like. Such techniques are disclosed in Non-Patent Documents 1 and 2, for example.

  In the conventional weight determination method, first, for example, initial weights (relative amplitude ratio and phase difference) are given to a plurality of antenna elements of a mobile phone. Next, radio waves are transmitted using all the antenna elements, and the radiation efficiency is calculated and / or measured. Further, the weight value for each antenna element is changed, radio waves are transmitted from all antenna elements, and the radiation efficiency is calculated and / or measured. Similarly, the radiation efficiency is obtained for all weights (all combinations of amplitude ratio and phase difference). The weight that gives the best radiation efficiency is finally determined as the weight for the transmitting antenna element of the mobile terminal.

  On the other hand, a radiation pattern integration method is known as a technique for measuring radiation efficiency and measuring radiation power as a basis thereof. The radiation pattern integration method measures the power from the wireless terminal with one fixed sensor, and changes the positional relationship between the wireless terminal (including the mobile terminal) and the sensor, and surrounds the wireless terminal (all solid angles). The antenna radiation pattern is determined by measuring and integrating the power over time. The sensor may receive the horizontal and vertical polarization components simultaneously with orthogonal two-polarization antennas, or may receive each component separately by switching the arrangement direction of one polarization antenna. This type of radiation pattern integration method is described in Non-Patent Documents 3 and 4, for example. Another example of the power measurement method is the random field method, in which a large number of scatterers are appropriately placed in the room where the measurement is performed, the radio waves emitted from the wireless terminal are scattered, and the received scattered wave statistics are used. Measure the radiation efficiency.

Tomoaki Nishikido, et al., “Parallel 2-element distributed feeding antenna element for portable wireless devices”, IEICE Society Conference B-1-190, 2003 Ryo Yamaguchi, et al., “Improvement of mobile phone efficiency by distributed power supply”, IEICE Society Conference B-4-4, 2003 Tatsuo Sakuma, et al., "A Study on Radiation Efficiency Measurement of Small Antennas", 2000 Hokkaido Association of Electrical Engineering Society, p. 202 Qiang CHEN, et al., “Measurement of Power Absorption by Human Model in the Vicinity of Antennas”, IEICE TRANS.COMMUN., VOL.E80-B, NO.5, MAY 1997, p.709-711

However, in order to determine the weight by the conventional method, it is necessary to perform the calculation and / or measurement so that all the possible weights are covered by sequentially changing the phase and the amplitude. There is a problem in that it cannot be said to be a proper weight determination method. In addition, labor required for calculation is not a little. In general, it is advantageous to increase the number of antenna elements from the viewpoint of increasing directivity. However, as the number of antenna elements increases, the computational burden required to determine those weights increases significantly, making it difficult to quickly determine the weights. For example, assume that there are 10 amplitude ratios between two antenna elements from 0.1 to 1 in increments of 0.1, and there are 360 phase differences from 0 to 359 degrees in increments of 1 degree. In this case, the total number of possible weights in the case of two elements is 10 × 360 = 3600. In the case of 3 elements, the number is further 3600 × 3600, and in the case of N elements, the number of combinations is as large as 3600 ^N−1 (the calculation burden increases depending on the number of elements minus the first power). . With the recent increase in the speed and capacity of computers, concerns regarding the computational burden are gradually being resolved, but such a burden in the development of simple small mobile terminals is still large.

  As for the power measurement method, in the radiation pattern integration method as shown in Non-Patent Document 3, it is necessary to obtain a power measurement value for all solid angles, so the wireless terminal is rotated in the θ direction and / or the φ direction. Many times, it takes a long time to measure. When investigating the influence of the surrounding environment (for example, the human body) of the wireless terminal, a large-scale device configuration that rotates not only the wireless terminal but also the surrounding environment is necessary, and it is difficult to measure easily. In this regard, as shown in Non-Patent Document 4, by moving both the sensor and the wireless terminal, for example, the sensor is in the elevation angle direction, and the wireless terminal is in the azimuth angle direction. By making each movable, the device configuration can be simplified. However, since the number of measurement points is the same, it takes a long time to measure. It is also conceivable that a plurality of sensors are provided along a meridian instead of one sensor, and one analyzer for analyzing power (for example, a spectrum analyzer) is connected while switching to each sensor. However, even if it does so, it must be measured while rotating the wireless terminal side, and still takes a long time for the measurement. Sometimes it is inappropriate to rotate objects in the surrounding environment at high speed. On the other hand, the random field method does not require an anechoic chamber and can measure radiation efficiency at a relatively high speed, but has a problem that it is not easy to evaluate and adjust the measurement environment including the location of the scatterer.

  The present invention is intended to address at least one of such problems, and a first problem thereof is that the weight of each antenna element of a mobile terminal that performs radio transmission using a plurality of antenna elements is efficiently calculated. It is to provide a weight determination device and a weight determination method that can be determined automatically.

  A second problem of the present invention is to provide a radiated power measuring apparatus and a radiated power measuring method capable of measuring the radiated power of a wireless terminal at high speed.

The radiated power measuring device used in one aspect of the present invention is:
A wireless terminal that emits radio waves,
A plurality of sensors provided at a distance from the wireless terminal and receiving the radio wave;
Combining means having a plurality of transmitting antennas connected to the plurality of sensors, and a receiving antenna for receiving signals transmitted from each of the plurality of transmitting antennas;
Analyzing means for analyzing a signal received by the receiving antenna, wherein the transmitting antenna connected to a sensor of the plurality of transmitting antennas has an electric field vector component of a radio wave received by the sensor from the wireless terminal. It is a radiated power measuring device characterized by transmitting the electric wave which it has.

  According to the present invention, it is possible to measure the radiated power of a wireless terminal at high speed.

1 shows a conceptual diagram of a weight determination system according to an embodiment of the present invention. FIG. It is a figure which shows a mode that the antenna element for test radio waves is scanned along a spherical surface. 4 is a flowchart illustrating a weight determination method according to an exemplary embodiment of the present invention. It is a figure which shows a mode in the case of using many antenna elements for test radio waves. It is a figure which shows the mobile telephone which has three antenna elements. 1 shows an overall view of a radiation power measurement system according to an embodiment of the present invention. FIG. It is a flowchart which shows the operation | movement in the measurement system shown by FIG. The figure at the time of comparing the method by one Example of this invention with the conventional method from various viewpoints is shown. A simulation result comparing the method according to the present embodiment and the conventional method is shown. 1 shows an overall view of a radiation power measurement system according to an embodiment of the present invention. FIG. It is a flowchart which shows the operation | movement in the measurement system shown by FIG.

  According to one aspect of the present invention, test radio waves radiated from one or more test wave sources provided outside a phantom that simulates a medium that causes radio wave loss are received by a plurality of antenna elements provided in a mobile terminal. The The weight of each antenna element is determined so that the signal received for each antenna element is strongly received as a whole. The weight that maximizes the total received power realizes an antenna pattern that minimizes the loss of radio waves, maximizes transmission efficiency during transmission, and consequently minimizes radio waves that are absorbed by the phantom.

  According to an aspect of the present invention, the signal received by the plurality of antenna elements is a signal transmitted from one test wave source provided non-fixed outside the phantom. Thereby, the number of test wave sources can be saved.

  According to an aspect of the present invention, the signals received by the plurality of antenna elements are signals transmitted from a plurality of test wave sources fixedly provided outside the phantom. Thereby, the weight can be determined promptly.

  According to one aspect of the present invention, the test wave source can emit radio waves polarized in an arbitrary direction. The test wave source is a random wave source that emits a test radio wave that is instantaneously polarized in a certain direction but is isotropic when averaged over time. Thus, the weight can be determined in consideration of not only the polarization in a specific direction but also all the polarization directions.

  According to one aspect of the present invention, radio waves radiated from a wireless terminal are received by a plurality of sensors provided at a distance from the wireless terminal, and individual signals obtained by the plurality of sensors are: The signals are wirelessly transmitted separately, spatially combined, and the power of the combined signal is analyzed. Since the power of the spatially synthesized signal is analyzed, the field emission pattern may not be known, but the total power emitted from the wireless terminal can be measured quickly.

  According to one aspect of the present invention, a plurality of signals input to the combining unit are wirelessly transmitted separately and spatially combined with a disturbance representing fading. This makes it possible to randomly change the weight at the time of combining the outputs from the sensors, and by averaging the instantaneous power measurement values after combining, the measurement accuracy can be improved.

  According to an aspect of the present invention, the plurality of sensors are provided in a region belonging to a part of solid angles centered on the wireless terminal. For example, by providing a plurality of sensors in the upper hemisphere region (by omitting the contribution on the ground side), the number of sensors can be saved while improving the efficiency of measurement.

  According to an aspect of the present invention, the plurality of sensors are provided over all solid angles centered on the wireless terminal. Thereby, it is possible to improve the accuracy of measurement.

  According to one aspect of the present invention, the plurality of sensors output a signal indicating a horizontal polarization component and a signal indicating a vertical polarization component of the received radio wave. Thereby, a polarization component in an arbitrary direction can be taken into consideration.

  According to one aspect of the present invention, a plurality of samples (instantaneous values) representing the output signal from the synthesizing unit are averaged, and the averaged signal is analyzed by the analyzing unit. Thereby, the improvement of the power measurement accuracy can be achieved.

  According to one aspect of the present invention, instead of or in addition to the combining means, a distributing means connected to a plurality of wave sources and an analyzing means for analyzing the power of the signal received by the wireless terminal are provided. . The signal input to the distributing means is wirelessly transmitted and spatially distributed to each of the plurality of wave sources (a process reverse to the above spatial synthesis is performed). The plurality of wave sources each transmit a radio signal in accordance with a signal obtained from the distribution unit. Thereby, a transmission side and a receiving side can be made reverse to said aspect.

  FIG. 1 is a conceptual diagram of a weight determination system according to an embodiment of the present invention. This system includes a mobile phone 102, a test radio wave antenna element 104, signal generators 106 and 108, and a weight determination unit 112. The mobile phone 102 is provided with a plurality of antenna elements 114 and 116, which are connected to the transceivers 118 and 120. In this system, an element 122 called a human body pseudo phantom (phantom) is provided, and a mobile phone 102 is provided in the vicinity of the human body pseudo phantom 122. The test radio wave antenna element 104 is provided outside the human body pseudo phantom 122. The test radio wave antenna element 104 is non-fixedly positioned on the spherical surface surrounding the human body pseudo phantom 122 as shown in FIG.

  The mobile phone 102 shown in FIG. 1 includes antenna elements 114 and 116 whose weights are determined by this system. In the present embodiment, for simplicity, it is assumed that two antenna elements are provided. However, for example, as shown in FIG. 5, two or more antenna elements can be provided as necessary. In the example of FIG. 5, three antenna elements 114, 115, 116 and three transceivers 118, 119, 120 connected to each are provided.

  A test radio wave antenna element 104 shown in FIG. 1 is an antenna element capable of emitting radio waves polarized in an arbitrary direction, and is a biaxial dipole antenna element in this embodiment. This antenna element is a combination of two dipole antenna elements capable of transmitting radio waves polarized in a certain axial direction so as to be orthogonal to each other.

  The signal generators 106 and 108 are connected to the respective axes of the test radio wave antenna element 104 and operate to excite the antenna elements in the respective axis directions. The signal generators 106 and 108 and the test radio wave antenna element 104 form a test wave source. The test wave source in the present embodiment is a random wave source, which radiates a test radio wave that is instantaneously polarized in a certain direction but is isotropic when averaged over time. The test radio wave radiated is instantaneously equivalent to a radio wave polarized in the direction of a certain elevation angle θ and a certain azimuth angle φ. However, by generating a large number of test radio waves while randomly changing the polarization direction, the polarization direction can be distributed isotropically and consequently randomized. In the present embodiment, a test wave source whose polarization direction changes at random in such a manner is used. In other words, a special test radio wave antenna element 104 having two degrees of freedom in the polarization direction is employed so that radio waves whose polarization direction changes in such a manner can be generated one after another.

  The antenna elements 114 and 116 of the mobile phone 102 receive the test radio waves radiated from the test radio wave antenna element 104, respectively. The reception signal received by each antenna element is given to the weight determination unit 112 through reception processing in each of the transceivers 118 and 120.

  The weight determination unit 112 determines a weight (relative amplitude ratio and phase difference) appropriate for each antenna element 114 and 116 based on the received signal received from each antenna element 114 and 116.

The human body pseudo phantom 122 is a medium (lossy medium) for losing radio waves that represents the head of the human body, for example. For simplicity, the human body pseudo phantom 122 has a cubic shape with a side of about 20 cm in this embodiment, but other arbitrary shapes can naturally be adopted. As an example, the relative permittivity ε _r of the human body pseudo phantom is 41, and the conductivity σ is 1.3 S / m. The human body phantom defines a prohibited area where radio waves should not be directed when wirelessly transmitting from a mobile phone. The main purpose of setting such a prohibited region is to reduce power loss in the region through the method described below. However, not only that, but also when there is an electronic device that should not cause electromagnetic interference in the region, such an electronic device is not affected.

  FIG. 3 shows a flowchart for determining the weight of the antenna element according to the present embodiment. The flow begins at step 302 and proceeds to step 304.

In step 304, a test radio wave is transmitted from a certain place (initial position) outside the human body pseudo phantom. The initial position may be a point A or B on the spherical surface shown in FIG. 2, or another point. A test radio wave whose polarization direction changes randomly every moment is radiated from the test radio wave antenna element 104. This test radio wave is received by each of the plurality of antenna elements 114 and 116 provided in the mobile phone 102. Then, after receiving processing in the transceivers 118 and 120, the weight determination unit 112 receives the received signal for each antenna element, that is, the electric field time response V ⁽¹⁾ (t), V ⁽²⁾ (t) in each antenna element. Is input.

In step 306, the electric field time response V ⁽¹⁾ (t), V ⁽²⁾ (t) for each antenna element is evaluated (determined). These may be obtained by experiments, or may be calculated using the following relational expression.

^{_{V (1) (t) =}} E 1x · n x (t) + E 1y · n y (t) + E 1z · n z (t)
^{_{V (2) (t) =}} E 2x · n x (t) + E 2y · n y (t) + E 2z · n z (t)
_Here, n _{x (t),} a coordinate component of the _{n y (t), n z} (t) white noise vector n whose band is limited _{(t), E 1x, E} 1y, E 1z first , E _2x , E _2y , and E _2z are the components of the electric field response to the second antenna element 116. If these quantities are known in advance, the electric field time response can be obtained numerically without experimentation. The electric field response or its component (such as E _1x ) is time independent and is referred to as “stationary electric field response” where appropriate.

  In step 308, it is determined whether test radio waves have been transmitted from all scanning points on the spherical surface surrounding the human body pseudo phantom. If not, the process proceeds to step 310.

  In step 310, the scanning point is updated to the next location, the flow proceeds to step 304, and a test radio wave is transmitted from the new location. Thereafter, the same procedure is repeated. If it is determined in step 308 that test radio waves have been transmitted from all scanning points, the flow proceeds to step 312.

  In step 312, the probability density distribution for the electric field time response determined in step 306 is evaluated. From the electric field time response for each antenna element, a probability density distribution over a period relating to the relative amplitude ratio and phase difference of the radio waves received by each antenna element is determined.

  In step 314, while evaluating the probability density distribution, an amplitude ratio and a phase difference (that is, weight) such that the radio wave received by each antenna element becomes stronger as a whole is obtained by, for example, a maximum ratio combining method.

As an example of this process, first, the covariance matrix R is calculated based on the electric field time responses V ⁽¹⁾ (t), V ⁽²⁾ (t). The matrix element R _ij of the covariance matrix R is defined as the sum of the product of the electric field time response V ⁽ⁱ⁾ (t) and the complex conjugate of V ^(j) (t) over a period of time.

R _ij = ΣV ⁽ⁱ⁾ (t) · V ^(j) (t) ^*
However, * means taking a complex conjugate. Using the covariance matrix calculated in this way, a weight that increases the received power is calculated. More generally, by executing an adaptive algorithm including these series of procedures, a weight that increases the total received power of the test radio wave can be obtained.

  Once the weight is calculated, the flow proceeds to step 316 and ends.

  As described above, according to the present embodiment, the total received power (total received power from each point) of the test radio wave emitted from the test wave source antenna element 104 provided outside the human body pseudo phantom 122 is increased. The weights of the antenna elements 114 and 116 of the mobile phone 102 are set. When the mobile phone 102 transmits wirelessly while feeding power to the plurality of antenna elements 114 and 116 using this weight, the transmission efficiency of the mobile phone 102 increases for the following reason. The fact that the total received power from the test wave source antenna element 104 at each point is maximized in the cellular phone 102 means that reception is possible with the least amount of radio wave loss. Due to the reversibility of transmission and reception, when radio waves are transmitted from the mobile phone with the same weight and the same frequency, the loss of radio waves is minimal and the transmission efficiency is maximized. As a result, the weight determined in this way is a weight that suppresses the transmission of radio waves to a prohibited area where the radio waves should not be directed at the time of transmission (in the situation where many radio waves are transmitted to the prohibited area) , The loss of radio waves will increase and the transmission efficiency will not be maximized.)

  According to the present embodiment, steps 304 to 310 are repeated, and the electric field time response is calculated by sequentially changing the location of the test wave source so that all the scanning points are covered, and the establishment density distribution is evaluated ( By performing step 312), the weight is determined (step 314). Since the number of scanning points is not an amount that rapidly increases as the number of antenna elements increases, according to the present embodiment, it is possible to determine the weight efficiently with less calculation burden than the conventional method (conventional method). According to the method, the calculation burden increased rapidly depending on the number of antenna elements minus the first power).

  In this example, the test wave source was a random wave source. Suppose that the test wave source is not a random wave source but a wave source that emits only polarized light fixed in a certain direction. In this case, only radio waves polarized in a specific direction are received by the antenna elements 114 and 116, and a weight that maximizes the total received power for all points on the spherical surface is obtained in step 308 of FIG. A radio wave transmitted with low loss at the time of transmission using this weight is a radio wave polarized in a specific direction. However, the transmitted radio wave also has a power component polarized in the other direction. Therefore, even if the total received power of radio waves polarized in a certain direction can be maximized, if there are polarization components in other directions, the total received power is not maximized and is determined as such. The weight does not maximize the transmission efficiency. By determining the weight so as to increase the total received power of the randomly deflected radio waves from the random wave source, it is possible to reliably maximize the total received power of the test radio waves and maximize the transmission efficiency during transmission. .

  In this embodiment, a dipole antenna element is used as the test radio wave antenna element. However, as long as it functions as a random wave source, any antenna element may be used instead of the dipole antenna element. For example, it is desirable to employ a loop antenna element from the viewpoint of ease of impedance matching and ease of manufacture. From the viewpoint of ease of analysis based on the electric field level, it is desirable to employ a dipole antenna element. Further, from the viewpoint of further randomizing the polarization direction, it is desirable to use a triaxial antenna element (x, y, z) instead of a biaxial antenna element (x, y). .

  FIG. 4 is a conceptual diagram of a weight determination system according to an embodiment of the present invention. In this embodiment, a large number of test radio wave antenna elements 104 are fixedly provided on a spherical surface surrounding the human body pseudo phantom 122. Each antenna element is provided with a signal generator as shown in FIG. Each of the test radio wave antenna element and the corresponding signal generator constitutes a random wave source. In this embodiment, the test radio wave is not radiated while moving one test radio wave antenna element along the spherical surface, but the test radio waves are radiated simultaneously from a plurality of test radio wave antenna elements. The weight is determined so that the power of the signal received by each antenna element of the mobile phone 102 is maximized. According to the present embodiment, it is possible to quickly determine the weight based on the power of simultaneously received signals without scanning one test radio wave antenna element within a predetermined area (for example, an area on a spherical surface). it can. The method according to the first embodiment is desirable from the viewpoint of saving the number of test radio wave antenna elements. Further, a combination of Example 1 and Example 2 may be used to provide a part of the test radio wave antenna elements non-fixed and a part of the test radio wave antenna elements.

  FIG. 6 illustrates a measurement system for measuring radiated power according to one embodiment of the present invention. In the present embodiment, the power of the signal transmitted from the wireless terminal is quickly measured. The measurement system includes a wireless terminal 602 such as a mobile terminal, a number of orthogonal sensors 604, a random RF synthesizer 606, and an analyzer 608.

  The wireless terminal 602 can be any device that emits radio waves to be measured. Accordingly, the wireless terminal 602 may be a mobile terminal or a computer or the like that has a wireless communication function but is fixedly installed. A signal included in the radiated radio wave is also arbitrary, and is not limited to a specific signal content or signal format.

Many orthogonal sensors 604 are provided on a spherical surface surrounding the wireless terminal 602, that is, a plurality of orthogonal sensors 604 are provided at equal distances from the center point of the wireless terminal 602. More specifically, the orthogonal sensor 604 may be provided on the surface of an icosahedron surrounding the wireless terminal 602 made of a metal plate. Moreover, such a polyhedron shape may be formed in a mesh shape with an insulator such as plastic or ceramics. The quadrature sensor 604 is an element that can receive or detect a radio wave radiated from the wireless terminal 602. The orthogonal sensor 604 can distinguish and detect the electric field vector components of the horizontal polarization (Eφ) and the vertical polarization (Eθ). As shown in the figure, the elevation direction is expressed by θ, and the azimuth direction is expressed by φ. In the illustrated example, K orthogonal sensors 604 are provided, and 2K signals (Eθ ⁽¹⁾ , Eφ ⁽¹⁾ ,..., Eθ ^(K) , Eφ ^(K) ) are output.

  In this embodiment, a large number of orthogonal sensors 604 are provided uniformly over the entire area (all solid angles) surrounding the wireless terminal 602. However, the orthogonal sensor 604 may be provided so as to cover some solid angles. For example, the region where the orthogonal sensor 604 is provided may be limited to the range of −90 ° ≦ θ ≦ 90 ° and 0 ≦ φ ≦ 360 °, and the area below the ground may be omitted from consideration. Alternatively, the area where the orthogonal sensor 604 is provided is limited to a range of 0 ≦ φ ≦ 45 °, and the number of sensors can be saved by measuring the power while rotating the wireless terminal 602 eight times (360 ° ÷ 45 °). You can also. However, if the orthogonal sensors 604 are provided in the entire area as in this embodiment, it is not necessary to rotate the wireless terminal 602. Therefore, data from all measurement points can be collected at one time, and power measurement is performed at high speed. be able to.

The random RF synthesizer 606 is wired to the outputs of the plurality of orthogonal sensors 604 and receives 2K signals. The random RF synthesizer 606 individually retransmits the input 2K signals as radio signals from the K antennas. For example, the first antenna transmits a radio signal expressed by (Eθ ⁽¹⁾ , Eφ ⁽¹⁾ ). Similarly, the kth antenna transmits a radio signal expressed by (Eθ ^(k) , Eφ ^(k) ). These radio signals are received by one antenna, and a plurality of radio signals are spatially combined.

  In this embodiment, a synthetic weight that randomly changes at the time of this spatial synthesis is used. From the viewpoint of accurately measuring the power radiated from the wireless terminal, as in the conventional pattern integration method, measure the power at a certain coordinate point (θ, φ), integrate the measured value while changing the measurement point, It is desirable to examine the power distribution (however, as described above, this method requires a long time for measurement). In this embodiment, the individual power values (and thus the power distribution) at each coordinate point (θ, φ) are not obtained, but are transmitted from the wireless terminal by the power of the signal after spatial synthesis (after vector synthesis). Approximate the power of the signal. If the synthesis weight at the time of spatial synthesis is fixed, the approximation accuracy may be deteriorated due to the position of the orthogonal sensor, the antenna, the phase shift, or the like. By employing a synthetic weight that randomly changes and averaging a large number of signal samples representing the synthesized signal, approximation accuracy and measurement accuracy can be improved.

  In this embodiment, fading is introduced into wireless communication between the retransmission trust antenna and the combining antenna in order to randomly change the combining weight. As an example, fading is introduced by randomly disturbing electromagnetic fields in the vicinity of a plurality of retransmission-reliable antennas in the random RF synthesizer 606. For example, a plurality of retransmission trust antennas are provided around a disc on which metal pieces are scattered, and radio waves are emitted from each antenna while the disc is rotated. The emitted radio wave is scattered by the metal piece and randomly disturbed before reaching the antenna on the synthesis side. In this way, the signals retransmitted from the respective antennas are combined while being subjected to fading separately.

  In the case of simulating such a random RF synthesizer 606, as an example, the combined power can be obtained by performing signal processing as shown in the following equation.

ここで、Ｅθ^（ｋ），Ｅφ^（ｋ）はそれぞれｋ番目のセンサから得られた電界ベクトル成分（定常的な電界応答）であり、時間によらない一定値である。Ｎθ^（ｋ）（ｔ），Ｎφ^（ｋ）（ｔ）は、それぞれ帯域制限された白色雑音信号のθ成分及びφ成分であり、ｋ番目のセンサに対するＲＦ合成ウエイトを表し、時間と共に変化する関数である。従って、ＲＦ合成装置６０６の出力である合成信号Ｅ（ｔ）は、時間に依存する関数である。このように、シミュレーションでは、時間に依存しない電界ベクトル成分Ｅθ^（ｋ），Ｅφ^（ｋ）と、雑音成分Ｎθ^（ｋ），Ｎφ^（ｋ）とが別個に分離されているが、実際の装置では（２）式に示されるような乗算演算が行なわれるのではなく、合成信号Ｅ（ｔ）が実測されることに留意を要する。

Here, Eθ ^(k) and Eφ ^(k) are electric field vector components (stationary electric field responses) obtained from the k-th sensor, and are constant values independent of time. Nθ ^(k) (t) and Nφ ^(k) (t) are the θ component and φ component of the band-limited white noise signal, respectively, representing the RF synthesis weight for the kth sensor, and a function that varies with time. It is. Therefore, the synthesized signal E (t) that is the output of the RF synthesizer 606 is a function that depends on time. As described above, in the simulation, the time-independent electric field vector components Eθ ^(k) and Eφ ^(k) and the noise components Nθ ^(k) and Nφ ^(k) are separated separately, but in an actual apparatus, It should be noted that the composite signal E (t) is actually measured rather than the multiplication operation shown in the equation (2).

Incidentally, in order to obtain the electric field vector components Eθ ^(k) , Eφ ^(k), power and the like of the signals received by the sensors, a device such as the analyzer 608 may be connected to the sensors. If analysis devices are provided for all sensors, it is theoretically possible to know the power distribution (radiation pattern) in addition to the power at each sensor point. However, providing a large number of analyzers is not realistic. Even if one analyzer is connected while switching to a large number of sensors, it takes a certain amount of time to obtain individual measurement values, and therefore it takes a long time to collect and analyze all K measurement values. In the present embodiment, the power of the signal transmitted from the wireless terminal is approximated by the power of the signal after spatial synthesis without obtaining the individual power value and power distribution at each coordinate point (θ, φ). By averaging such instantaneous power measurement values, approximation accuracy and measurement accuracy can be improved.

  Note that the method of randomly changing the composite weight is not limited to the introduction of the fading described above. For example, a varactor diode may be provided at the output unit of each sensor to adjust the directivity of the sensor.

The analyzer 608 can perform power measurement and other processes based on the signal output from the random RF synthesizer 606. For example, the analysis device 608 can be an oscilloscope, a spectrum analyzer, a network analyzer, a field strength measuring device, or other analysis device. In the simulation, the average power P _ave as shown in equation (3) is calculated based on the combined signal E (t) calculated according to equation (2). Based on the power measured in this way, for example, the radiation efficiency η as shown in equation (4) can be calculated. Here, P _AUT represents the measured power, and P _dipole is the power obtained by the analyzer 608 when the radio terminal 602 transmits a radio wave from the dipole antenna, and is an amount used as a reference for calculating the radiation efficiency. is there. For example, in a situation where no human body pseudo phantom is provided, the power of a signal transmitted from a dipole antenna is measured, and the value is defined as P _dipole . Then, _let P _AUT be the power of the signal transmitted with the human body phantom provided. The transmission efficiency η = P _AUT / P _dipole calculated in this way represents a change in transmission efficiency due to the human body pseudo phantom.

  FIG. 7 shows a flowchart for explaining the operation of the measurement system shown in FIG. The flow begins at step 702 and proceeds to step 704.

  In step 704, radio waves are radiated from the wireless terminal 602.

In step 706, radio waves radiated from the wireless terminal 602 are received by a number of orthogonal sensors 604. Each orthogonal sensor gives a received electric field vector (Eθ ⁽ⁿ⁾ , Eφ ⁽ⁿ⁾ ) to the random RF synthesizer 606.

  In step 708, 2K signal components of the received electric field vector are retransmitted from the K antennas.

  In step 710, a disturbance representing fading is introduced so that the signals transmitted from the K antennas are spatially combined with random weights by one antenna. Step 708 and step 710 are depicted separately for convenience of explanation, but in practice they are not performed separately in stages, but at least partially.

  In step 712, the power of the combined signal is measured and analyzed. Thereafter, the flow proceeds to step 714 and ends.

  FIG. 8 shows a list when the method according to the present embodiment is compared with the conventional method (pattern integration method and random field method) from various viewpoints. As shown in the drawing, in this embodiment, a large number of sensors are fixedly arranged over all solid angles, and scanning is not necessary. In the pattern integration method, it is necessary to scan one sensor and rotate the wireless terminal. In the random field method, one sensor is fixedly provided at a specific position, and scanning is unnecessary. In this embodiment, the measurement time is short, but the conventional method requires a long time. In the present embodiment, unlike the pattern integration method and the like, it is not necessary to rotate the measurement target (wireless terminal or the like), so that power measurement is easy even if the surrounding environment includes a human body or other objects. In the present embodiment, in order to suppress deterioration in measurement accuracy due to reflected waves, it is necessary to perform measurement in an anechoic chamber whose indoor wall surface is covered with a radio wave absorber.

  FIG. 9 shows a simulation result comparing the method according to the present embodiment and the pattern integration method (conventional method). This simulation result shows the relationship between the number of samples (horizontal axis) when averaging instantaneous synthesized signals from the random RF synthesizer 606 and the calculated radiation efficiency η (vertical axis). In the figure, a graph indicated by reference numeral 902 indicates a calculation result by the pattern integration method. As shown in the figure, with this method, the radiation efficiency can be accurately calculated even if the number of samples is small. However, measurement takes a long time. On the other hand, the graph indicated by reference numeral 904 indicates the calculation result according to the above-described embodiment. As shown in the figure, it can be seen that the accuracy of the radiation efficiency is improved as the number of samples for averaging increases, and is generally converged when the number of samples is about 10,000 points or more (the error is less than 1%). In this embodiment, since the composite signal E (t) is obtained instantaneously, power measurement can be performed in a short time. For example, if the number of samples required for averaging is 10000 points, the measurement sampling frequency is 100 kHz, and data is captured by a digital oscilloscope, the measurement value collection time is 100 ms. If the data update rate is about 1 second, the power value and the radiation efficiency can be measured almost in real time. Therefore, the present embodiment is very advantageous for the design and evaluation of radio terminals and other devices that emit radio waves.

  The power measurement according to the present embodiment can be widely applied not only to the weight determination as in the first and second embodiments but also to any application for measuring the radiated power of the wireless terminal. For example, the method according to the present embodiment is an inspection of whether or not the radio wave intensity radiated by the radio terminal is within the specification range in the product inspection of the radio terminal (for example, confirming that no radio wave exceeding 0,8 W is emitted. Can be used for inspection).

  According to the present embodiment, the radiated power and the radiation efficiency of the wireless terminal can be measured at a very high speed, so that the work efficiency such as the design efficiency and quality evaluation of the wireless terminal can be greatly improved.

  FIG. 10 shows an overall view of a measurement system for measuring radiated power according to an embodiment of the present invention. In the present embodiment, the signal transmission / reception relationship is opposite to that in the third embodiment. In this embodiment, the radio wave radiation efficiency and the like are calculated using the reversible nature of transmission and reception. The measurement system includes a wireless terminal 1002, a number of wave sources 1004, a random RF distribution device 1006, and an analysis device 1008.

  The wireless terminal 1002 receives the radio wave from the wave source 1004 and gives the received signal to the analyzer 1008.

The wave source 1004 is provided on a spherical surface surrounding the wireless terminal 1002. A number of wave sources 1004 wirelessly transmit radio waves to the wireless terminal 1002 in accordance with the signals received from the random RF distribution device 1006, respectively. Signals transmitted from each wave source 1004 are distinguished by electric field vector components of horizontal polarization (Eφ) and vertical polarization (Eθ). In the illustrated example, K orthogonal sensors 1004 are provided, and 2K signals (Eθ ⁽¹⁾ , Eφ ⁽¹⁾ ,..., Eθ ^(K) , Eφ ^(K) ) are given to them.

  Note that a large number of wave sources 1004 may be provided so as to cover a part of solid angles instead of the whole solid angle centered on the wireless terminal 1002.

The random RF distributor 1006 is wired to the inputs of a number of wave sources 1004. These 2K signals correspond to signals received by K antennas (not shown) in random RF distributor 1006. In the random RF distributor 1006, a signal is wirelessly transmitted from a certain node, and is received (distributed) by K antennas. For example, the first antenna receives a radio signal expressed by (Eθ ⁽¹⁾ , Eφ ⁽¹⁾ ). Similarly, the nth antenna receives a radio signal expressed by (Eθ ⁽ⁿ⁾ , Eφ ⁽ⁿ⁾ ). In this case, as with the random RF synthesizer 606 in FIG. 6, for example, fading is introduced so as to distribute the radio signal with randomly changing weights.

  FIG. 11 is a flowchart showing the operation of the measurement system according to this embodiment. The flow begins at step 1102 and proceeds to step 1104.

  In step 1104, in the random RF distribution apparatus, a signal is transmitted wirelessly from one node and received by K antennas. A disturbance representing fading is introduced so that the wirelessly transmitted signal is distributed to the K antennas with random weights.

In step 1106, the wave source 1004 corresponding to each of the K antennas transmits a signal to the radio terminal 1002 according to the signals (Eθ ⁽ⁿ⁾ , Eφ ⁽ⁿ⁾ ) obtained from the random RF distributor 1006. This transmission is performed simultaneously from K antennas.

  In step 1108, the signal received by the wireless terminal 1002 is measured and analyzed by the analysis device 1008. The flow then proceeds to step 1110 and ends.

  Hereinafter, the means taught by the present invention will be listed as an example.

(Section 1)
A plurality of antenna elements provided in a mobile terminal for receiving test radio waves radiated from one or more test wave sources provided outside a phantom that simulates a medium for losing radio waves;
A weight determination device comprising: weight determination means for determining a weight of each antenna element so that a signal received for each antenna element is strongly received as a whole.

(Section 2)
The weight determination apparatus according to claim 1, wherein the signals received by the plurality of antenna elements are signals transmitted from one test wave source that is non-fixedly provided outside the phantom.

(Section 3)
The weight determination apparatus according to claim 1, wherein the signals received by the plurality of antenna elements are signals transmitted from a plurality of test wave sources fixedly provided outside the phantom.

(Section 4)
2. The weight determination according to claim 1, wherein the test wave source is a random wave source that emits a test radio wave that is instantaneously polarized in a certain direction but is isotropic when averaged over time. apparatus.

(Section 5)
Radiating test radio waves from one or more test wave sources provided outside a phantom that simulates a medium that causes radio wave loss;
Receiving the radiated test radio wave by a plurality of antenna elements provided in the mobile terminal;
Determining the weight of each antenna element so that the signal received for each antenna element is strongly received as a whole.

(Section 6)
A wireless terminal that emits radio waves,
A plurality of sensors provided at a distance from the wireless terminal and receiving the radio wave;
Combining means for combining individual signals obtained from the wireless terminal through the plurality of sensors;
An analyzing means for analyzing the power of the combined signal, and the plurality of signals input to the combining means are separately wirelessly transmitted and spatially combined.

(Section 7)
The radiated power measuring device according to claim 6, wherein a plurality of signals input to the synthesizing unit are wirelessly transmitted separately and spatially synthesized with a disturbance representing fading.

(Section 8)
The radiated power measuring device according to claim 6, wherein the plurality of sensors are provided in a region belonging to a part of a solid angle centered on the wireless terminal.

(Section 9)
The radiated power measuring device according to claim 7, wherein the plurality of sensors are provided over all solid angles centered on the wireless terminal.

(Section 10)
A plurality of wave sources provided at a distance from the wireless terminal;
Distribution means connected to the plurality of wave sources;
Analyzing means for analyzing the power of the signal received by the wireless terminal, the signal input to the distributing means is wirelessly transmitted, and a plurality of antennas provided corresponding to each of the plurality of wave sources Received by
The plurality of wave sources each transmit a radio signal in accordance with a signal obtained from the distribution unit.

(Section 11)
Radio waves are emitted from the wireless terminal,
The plurality of sensors provided at a distance from the wireless terminal receives the radio wave,
Individual signals obtained by the plurality of sensors are wirelessly transmitted separately, spatially combined,
A method for measuring a radiated power, characterized by analyzing the power of the combined signal.

(Section 12)
A signal input to a certain node is wirelessly transmitted and received by a plurality of antennas provided corresponding to each of a plurality of wave sources provided at a distance from the wireless terminal,
Radio signals are transmitted from the plurality of wave sources according to the signals received by the respective antennas,
A method of measuring a radiated power, wherein the power of a signal received by the wireless terminal is analyzed.

102 mobile phone; 104 antenna element for test radio wave; 106, 108 signal generator; 112 weight determining unit; 114, 115, 116 antenna element; 118, 119, 120 transceiver; 122 human body phantom;
602 wireless terminal; 604 quadrature sensor; 606 random RF synthesizer; 608 analyzer;
1002 Wireless terminal; 1004 Wave source; 1006 Random RF distributor; 1008 Analyzer

Claims (7)

A wireless terminal that emits radio waves,
A plurality of sensors provided at a distance from the wireless terminal and receiving the radio wave;
Combining means having a plurality of transmitting antennas connected to the plurality of sensors, and a receiving antenna for receiving signals transmitted from each of the plurality of transmitting antennas;
Analyzing means for analyzing a signal received by the receiving antenna, wherein the transmitting antenna connected to a sensor in the plurality of transmitting antennas has an electric field vector component of a radio wave received from the wireless terminal by the sensor A radiated power measuring device characterized by transmitting radio waves. The radiated power measuring apparatus according to claim 1, wherein signals transmitted from each of the transmission antennas are spatially combined with a disturbance representing fading. The radiated power measuring apparatus according to claim 1, wherein the plurality of sensors are provided in a region belonging to a part of a solid angle centered on the wireless terminal. The radiated power measuring device according to claim 2, wherein the plurality of sensors are provided over all solid angles with the wireless terminal as a center. A plurality of wave sources provided at a distance from the wireless terminal;
A distribution means having a plurality of reception antennas connected to a plurality of wave sources, and a transmission antenna for transmitting a signal to each of the plurality of reception antennas;
Analyzing means for analyzing a signal received by the wireless terminal, and a wave source connected to a receiving antenna among the plurality of wave sources includes an electric field vector component of a radio wave received by the receiving antenna from the transmitting antenna. A radiated power measuring device characterized by transmitting radio waves having Radiating radio waves from a wireless terminal;
Receiving the radio waves by a plurality of sensors provided at a distance from the wireless terminal;
Transmitting signals separately from a plurality of transmitting antennas and receiving them by one receiving antenna;
Analyzing a signal received by the receiving antenna, wherein the transmitting antenna connected to a sensor within the plurality of transmitting antennas has an electric field vector component of the radio wave received from the wireless terminal by the sensor A method for measuring radiated power, characterized by transmitting radio waves. Transmitting a signal input to a certain node from a transmitting antenna, receiving it by a plurality of receiving antennas, transmitting a radio signal from a plurality of wave sources, and
Analyzing a signal received by a radio terminal provided at a distance from the plurality of wave sources, and the wave source connected to the receiving antennas of the plurality of wave sources includes: A method for measuring radiated power, comprising: transmitting a radio wave having an electric field vector component of a radio wave received from the transmitting antenna.

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