JP6893654B2 - Electromagnetic wave information visualization device - Google Patents

Description

An embodiment of the present invention relates to an electromagnetic wave information visualization device.

Information and communication equipment is becoming smaller and more sophisticated, and wireless communication services using this information and communication equipment and wireless lines such as wireless LAN (Local Area Network) or LTE (registered trademark) (Long Term Evolution) are rapidly becoming available. It is widespread. For example, mobile terminals such as smartphones, tablet terminals, and notebook personal computers have become indispensable both publicly and privately. Along with this, wireless LAN services such as Wi-Fi (registered trademark) are rapidly spreading in public spaces, public facilities, hospitals, offices, stores, etc., and are spreading throughout the country.

Along with this, radio waves are transmitted and received frequently over a wide area from wireless communication terminals and devices, and communication quality deteriorates due to interference between communication frequency bands, or other electronic devices and devices in the vicinity due to wireless radio waves. (See, for example, Non-Patent Document 1).

In addition, the drive frequency of internal circuits is becoming higher due to the higher functionality of devices, and there is concern about the influence of radiation noise in the microwave band.
With the recent development of IoT (Internet of Things) or 5G (5th generation mobile communication system), the number of devices has increased rapidly, and devices that did not communicate in the past have started to perform wireless communication. There is concern about deterioration of the wireless environment and communication failure due to the radiation noise of IoT (see, for example, Non-Patent Document 2).

Therefore, (1) deterioration of communication quality due to interference between communication frequency bands due to frequent and wide-area wireless communication, (2) influence of wireless radio waves from communication terminals / devices on other peripheral devices, and (3) terminals. There are three problems, the influence of radiated noise caused by the rapid increase in the number on wireless communication, and there is an urgent need for technology to efficiently and optimally control the radio wave environment and electromagnetic environment.

As a solution to realize these, a frequency-selective electromagnetic shield focusing on a frequency selective surface (FSS) used in the field of antenna technology has been studied (see, for example, Non-Patent Document 3). , This is a technology that appropriately controls when a place requiring treatment or a terminal / device can be identified, and for efficient factor identification, the wireless environment and electromagnetic noise visualization technology are the same as the above technology. Is required.

As a technique for visualizing electromagnetic waves, for example, in the case of electromagnetic waves in the optical region, there are cameras and the like. This is a technology realized by condensing visible light with a lens and creating an image. Visible light has a wavelength on the order of nanometers, and since the wavelength is sufficiently smaller than the size of the lens, it can act as a propagation path for the entire visible light, and condensing is realized. Of course, there are aberrations. Similar techniques have been proposed for the microwave band. For example, it is a method of condensing a radio wave of 2.45 [GHz], which is one of the unlicensed bands, with a lens and estimating the arrival direction and signal strength (see, for example, Non-Patent Document 4).

In addition, as electromagnetic environment (EMC) technology, a technology that scans an electromagnetic field probe to visualize the signal intensity distribution of noise, and a service that visualizes the signal intensity distribution of communication radio waves with a smartphone application (application program), etc. Exists (see, eg, Non-Patent Document 5).

Eiichi Murata, Shingaku Giho, AP2013-123, Nov. 2013. Teruo Tobana et al., IEICE Transactions B, Vol.J85-B No.2 pp.250-257, Dec. 2002. G. Itami et al., International Symposium on Antennas and Propagation (ISAP2017), 1066, Phuket, Thailand, Nov. 2017. A. Ohmae et al., International Symposium on Antennas and Propagation (ISAP2016), 4C2-1, Okinawa, Japan, Oct. 2016. Satoshi Yagiya et al., Shinawatra, EMCJ2009-106, Jan. 2010.

When trying to visualize the direction of arrival of an electromagnetic wave, the band is limited because the lens depends on the wavelength of the radio wave to be visualized at the time of focusing, and the bandwidth cannot be widened.
Although there is a technology for visualizing the arrival direction of wideband electromagnetic waves, this technology estimates only the radio frequency band specified by the Radio Law from the network side, and it is not possible to visualize various other electromagnetic noises. Can not.

Although there is a technology for visualizing wideband noise, it is necessary to scan the probe close to the device that emits the electromagnetic wave to be visualized, and it is not possible to visualize the direction of arrival of the wideband electromagnetic wave for the entire specific space. ..

The present invention has been made by paying attention to the above circumstances, and an object of the present invention is to provide an electromagnetic wave information visualization device capable of estimating the frequency and arrival direction of an electromagnetic wave in a short time and with high accuracy. It is in.

In order to achieve the above object, the first aspect of the electromagnetic wave information visualization device according to the embodiment of the present invention is that the electromagnetic wave information visualization device has an interval in which the frequency and the incident angle are shorter than the shortest wavelength of the incoming wave to be visualized. A radio wave separation unit that separates the incoming wave to form a scattered wave by a scatterer composed of the dielectrics or conductors arranged in the above, and a scattering unit composed of a connected conductor or dielectric material and formed by the radio wave separation unit. The waveguide that transmits the waves and the scattered waves transmitted by the waveguide are received by a plurality of sensors each arranged at intervals shorter than the shortest frequency and converted into an electric signal. By performing signal processing that solves the inverse problem when the signal strength of the electric signal converted by the receiving unit and the position of the sensor are used as outputs and the frequency and incident angle of the incoming wave are input. It is provided with a signal processing unit that estimates the combination of the frequency and the incident angle of the incoming wave.

In the second aspect of the electromagnetic wave information visualization device of the present invention, in the first aspect, the scatterer has a particle size at which the intensity of the scattered wave becomes a desired intensity, and any of the scatterers and any of them. The other scatterer or the sensor is arranged at a position different from the line connecting the sensor.

A third aspect of the electromagnetic wave information visualization device of the present invention, in the first or second aspect, is a plurality of lengths corresponding to the period of the scattered wave based on the arrival wave having the highest frequency, which is the object of the visualization. The reference interval formed by arranging the sensors and being equally divided by the number of arrays of the sensors in the cycle is p, the maximum integer less than half the number of arrays in the cycle is n, and the minute amount is defined as a minute amount. When δ is set, the minute amount is set so that 0 <nδ <p, and the plurality of sensors are n times the minute amount from the reference position in the cycle so that the arrangement positions do not overlap. They are arranged at positions that satisfy the conditions of.

According to the first aspect of the electromagnetic wave information visualization device according to the first embodiment of the present invention, the arrival wave is separated by a scattering body arranged at intervals shorter than the shortest wavelength of the arrival wave to be visualized to form a scattered wave. However, the combination of the frequency and incident angle of the incoming wave is estimated by performing signal processing that solves the inverse problem when the frequency and incident angle of the incoming wave are input with the position and signal strength of the sensor as the output. The incoming wave can be visualized after reducing the direct wave component of the scatterer.

According to the second aspect of the electromagnetic wave information visualization device according to the second embodiment of the present invention, the scatterer has a particle size at which the intensity of the scattered wave becomes a desired intensity, and any scatterer and an arbitrary sensor can be used. Since other scatterers or the sensor are arranged at a location different from the connecting line segment, the incoming wave should be visualized after increasing the intensity of the scattered wave and ensuring the linearity of the scattered wave. Can be done.

According to the third aspect of the electromagnetic wave information visualization device according to the third embodiment of the present invention, a reference interval is set which is equally divided by the number of sensor arrangements within the period of the scattered wave based on the arrival wave having the highest frequency. Since the sensors are arranged at positions based on the reference interval and so that the arrangement positions do not overlap, the amount of information obtained from the scattered wave can be guaranteed.

That is, according to the present invention, it is possible to estimate the frequency and the direction of arrival of electromagnetic waves in a short time and with high accuracy.

The figure which shows the application example of the wide band arrival wave information visualization apparatus which concerns on one Embodiment of this invention. The figure which shows an example of the analysis model which concerns on the signal acquisition of the scattering pattern of an incoming wave using electromagnetic field analysis. The figure which shows an example of the signal acquisition of the scattering pattern of the incoming wave using electromagnetic field analysis. The figure which shows an example of the simple theoretical model in the relationship between the scattering pattern of an incoming wave, and the received signal obtained by a sensor. The figure which shows an example of the relationship between a signal strength and a scattered wave. The figure explaining the contrast improvement of a scattering pattern. The figure which shows an example of the analysis model which concerns on the acquisition of the scattered electromagnetic field distribution when the parameter of a scatterer is changed. The figure which shows an example of the contrast characteristic of the scattering pattern of an incoming wave with respect to the change of the arrangement period of a scattering body. The figure which shows an example of the contrast of the scattering pattern of an incoming wave with respect to the change of the radius of a scatterer. The figure which shows an example of the correspondence relation about the amount of information, the amount of calculation, and the number of sensor arrangements. The figure which shows an example of the change of the amount of information and the amount of calculation with respect to the same sensor arrangement position. The figure which shows the specific example of the arrangement of a sensor.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.
(Overall configuration and its outline)
FIG. 1 is a diagram showing an application example of a wideband arrival wave information visualization device according to an embodiment of the present invention. In this embodiment, a wideband arrival wave information visualization device (electromagnetic wave information visualization device) 10 as shown in FIG. 1 will be described.
This device is a device having a radio wave separating unit 11, a waveguide unit 12, a receiving unit 13, and a signal processing unit 14, and as a whole, the frequency of the coming wave (arriving electromagnetic wave) in a wide band (for example, frequencies f ₁ and f ₂ ). -A device having a function of estimating an incident angle (arrival direction) (for example, incident angles θ ₁ and θ ₂ ), and an apparatus that estimates the arrival direction of a broadband electromagnetic wave not limited to a communication frequency without scanning.

The signal processing unit 14 can be realized by a system using a computer device such as a personal computer (PC). For example, a computer device includes a processor such as a CPU (Central Processing Unit), a memory connected to the processor, and an input / output interface. Of these, the memory is composed of a storage device having a storage medium such as a non-volatile memory. The function of the signal processing unit 14 can be realized, for example, by the processor reading and executing a program stored in the memory. Note that some or all of these functions may be realized by a circuit such as an application specific integrated circuit (ASIC).

In the following (1-1) to (1-4), the roles and functions of the radio wave separation unit 11, the waveguide unit 12, the reception unit 13, and the signal processing unit 14 will be described. In the following (2-1) to (2-3), the arrangement of the scatterers of the radio wave separation unit 11 will be described. In the following (3-1) and (3-2), the arrangement of the sensors of the receiving unit 13 will be described.

(1-1) Radio Wave Separation Unit 11 In the radio wave separation unit 11 shown in FIG. 1, a plurality of scatterers made of conductors or dielectrics are arranged (including both cases with and without periodicity). The radio wave separation unit 11 forms a scattered wave pattern (hereinafter, may be referred to as a scattering pattern) according to the frequency and the incident angle (arrival direction) by the scatterer for each arrival wave.
The radio wave separation unit 11 utilizes the fact that the arrangement interval of the scatterers causes an electromagnetic field scattering phenomenon (Rayleigh scattering) under the condition that the wavelength of the incoming wave to be visualized is less than the wavelength of the incoming wave to be visualized. Standardize. As a result, unlike a lens applied in a narrow band, an incoming wave having a wide target band for visualization can be separated according to the frequency and incident angle of the incoming wave.

(1-2) About the waveguide portion 12 The waveguide portion 12 shown in FIG. 1 is a transmission line composed of a plurality of connected conductors or dielectrics, and is formed by a radio wave separation unit 11 and has an incoming wave. The scattering pattern is transmitted to the receiving unit 13. The waveguide 12 may have various structures such as a parallel plate waveguide, a microstrip line, and a metamaterial transmission line. In particular, in order to increase the electrical length of the waveguide 12 beyond the space, it is possible to effectively increase the dielectric constant or the magnetic permeability by using a metamaterial, and to reduce the size of the waveguide 12 as a whole. Further, it is possible that none of the above structure is arranged at the location of the waveguide 12.

FIG. 2 is a diagram showing an example of an analysis model related to signal acquisition of a scattering pattern of an incoming wave using electromagnetic field analysis. The structure of the transmission line needs to be configured corresponding to the conditions (TE (Transverse Electric) mode, TM (Transverse Magnetic) mode) for forming the scattering pattern of the incoming wave.

For example, as shown in FIG. 2, a case where the parallel plate waveguide is the waveguide portion 12 will be described.
In the example shown in FIG. 2, the dimensions of the parallel plate waveguide are 10 [mm] in the x-axis direction, 90 [mm] in the y-axis direction, and 100 [mm] in the z-axis direction.
An example of the analysis conditions in this example is shown below. The angle of incidence is the angle between the incident wave from the bottom surface of the model and the z-axis.

(A) Incident angle: θ = 15 [°]
(B) Frequency band: 1.6 [GHz] (6 points for each 1 [GHz])
(C) Reception position: (x, z) = (0,100)
-40 ≤ y ≤ 4 (every 10 [mm], 9 points)
Here, an example of the signal calculation procedure will be described.

First, the numerical value of the field strength (absolute value) E extracted with 10 ° intervals in the range of up to 0 to 180 °, calculates the power density ^{P (=} E 2/377) for each extraction result.
Second, the power density P calculated for all the angles set at the above 10 ° intervals is integrated and averaged (average power) and treated as a received signal.

FIG. 3 is a diagram showing an example of signal acquisition of a scattering pattern of an incoming wave using electromagnetic field analysis. As shown in FIG. 3, the scattering pattern of the incoming wave can be separated by the waveguide 12 according to the frequency and the angle of incidence.

In the example shown in FIG. 3, the frequency _{f i (i = 1,3,5 [GHz} ]), showing the signal acquisition in the combination of the angle of incidence _{θ j (j = 15,30,45,60 [rad} ]). The horizontal axis of FIG. 3 is the sensor position [mm], and the vertical axis is the signal strength [W / m ² ] of the electric signal converted from the scattered wave. In this way, the scattering pattern of the incoming wave, which differs depending on the frequency and the angle of incidence, can be obtained. In addition, information on the incoming wave can be obtained by performing signal processing that solves the inverse problem by using the scattering pattern (sensor position, intensity) of the incoming wave as an output and the incoming wave (frequency, angle) as an input.

(1-3) Receiving unit 13 The receiving unit 13 receives the scattering pattern of the incoming wave transmitted by the waveguide unit 12 by a plurality of sensors, each of which is a conductor or a dielectric, and converts it into an electric signal. Examples of the element used as a sensor in the receiving unit 13 include a micro monopole antenna, a micro loop antenna, an EBG (Electromagnetic Band Gap) sensor, and a capacitive voltage probe. By connecting a detection diode or the like to this sensor, the receiving unit 13 can convert information on the electric field strength of the scattering pattern into electric power and obtain an electric signal.

Since the number of sensors represents the number of outputs, it is necessary to determine the number of sensors according to the amount of information obtained for the incoming wave. As a qualitative tendency, when the sensors are randomly arranged in the receiving unit 13, increasing the number of sensors increases the amount of information obtained for the incoming wave, so that the resolution of the frequency and incident angle of the incoming wave is increased. be able to.

For example, the number of incoming waves, the frequency of the incoming waves, the arrival wave angle of incidence, in case of representing the signal strength of the electrical signals at the respective ways 10 are conceivable scattering pattern 10 4 ⁽⁼ 10000) street. Therefore, when the number and signal quantization pattern is nine, and three ways each sensor, scattering pattern obtained by the receiver 13 ^{3 9 (≒ 20000 = 2 ×} 10 4) it becomes as, nine sensors If so, it is generally considered that the frequency and incident angle of the incoming wave (hereinafter, may be referred to as incoming wave information) can be obtained as a solution. There are exceptions due to duplication of the amount of information received by the sensor.

However, in consideration of the influence of crosstalk, care must be taken to maintain a sufficient distance between sensors according to the frequency band to be visualized. However, if the structure has an extended effective electrical length due to the metamaterial effect, such as an EBG sensor, the distance between the sensors can be shortened.

(1-4) Signal processing unit 14 The signal processing unit 14 derives the frequency and incident angle (arrival wave information) of the incoming wave based on the signal pattern obtained by the receiving unit 13. Specifically, the signal processing unit 14 solves the inverse problem of a linear multi-dimensional simultaneous equation that inputs the frequency of the incoming wave and the incident angle and outputs the position of the sensor of the receiving unit 13 and the signal strength of the electric signal. The incoming wave information is estimated by performing signal processing to be solved.

At this time, the analysis that is the basis of the processing by the signal processing unit 14 is the inverse scattering analysis, and the machine learning data generated by sufficiently learning the combination data of the input and the output in advance can be applied to this analysis. As a result, the solution can be derived more efficiently, and the amount of calculation by the signal processing unit 14 can be reduced.

When the frequency and incident angle of the incoming wave cannot be predicted at all, the signal processing unit 14 can estimate the incoming wave information by applying the supervised learning data prepared in advance. Further, when the frequency and the incident angle of the incoming wave can be predicted to some extent, the signal processing unit 14 can efficiently estimate the incoming wave information by applying clustering by unsupervised learning.

Outline of (2-1) to (2-3) FIG. 4 is a diagram showing an example of a simple theoretical model in the relationship between the scattering pattern of the incoming wave and the received signal obtained by the sensor.
The relationship between the scattering pattern of the incoming wave formed by the scattering body 100 of the radio wave separating unit 11 shown in FIG. 4 and the received signal obtained by the sensor of the receiving unit 13 can be expressed by a simple theoretical model. The scatterer 100 shown in FIG. 4 is sufficiently smaller than the wavelength of the incoming wave and assumes an electric dipole. It is also assumed that the scattered electromagnetic field changes depending on the incident angle of the incoming wave.

Here, for the scatterer 100, the following equation (1) having the charge density (scalar amount) ρ as the left side and the following equation (2) having the current density vector as the left side are assumed.

Further, the vector potential in the Lorenz condition can be expressed by the following equation (3) with this vector potential as the left side. C on the right side of equation (3) is the speed of light. K on the right side of the equation (3) is the absolute (scalar) amount of the wave number of the scattered wave when it is re-radiated from the scatterer by the incident electromagnetic wave.

For this equation (3), if the first term is taken by the power expansion of r (distance from the scatterer to the sensor), the following equation (4) is obtained.

Then, the following (6) and (7) are obtained based on the integral calculation and the relationship of the following equation (5).

The left side of equation (7) is the polarization vector of the scattered wave.
Based on the above equations (6) and (7), the following equation (8) that defines the magnetic flux density, and the following equation (9) that defines the electric field strength, the following equations (10) and (11) ) Are obtained respectively. N (vector notation) on the right side of the equation (10) is a unit vector in a direction parallel to the radial direction (plane direction perpendicular to the x-axis direction) of the scatterer, and is generally called a normal vector.

The following equation (12) can be used for the expansion in the equation (11).

Using equation (12), the following equation (13) with the signal strength in the y-axis direction as the left side can be obtained.

FIG. 5 is a diagram showing an example of the relationship between the signal strength and the scattered wave.
As shown in FIG. 5, the intensity of the signal obtained by the sensor of the receiving unit 110 represented by the equation (13) is the scattering of the incoming wave (frequency f ₁ , incident angle θ ₁ ) in consideration of only the primary scattering. wave _{(r 1, r 2, r} 3, ..., r n (n: constant)) can be added representation in the alignment of. That is, the signal obtained by the sensor means a signal obtained by each sensor receiving the sum of the radiated electromagnetic fields from each scatterer.

In order to increase the amount of information of the received signal obtained from the above model, it is required that the contrast of the scattering pattern is large. High contrast is physically interpreted as (a1) reducing the direct wave component of the scattered pattern, (a2) increasing the intensity of the scattered wave, and (a3) preventing the scattering wave from being attenuated and ensuring linearity. it can.
The solutions of the above (a1) to (a3) will be described in the following (2-1) to (2-3), respectively.

FIG. 6 is a diagram for explaining the improvement of the contrast of the scattering pattern.
As shown in FIG. 6, in order to improve the contrast of the scattering pattern 120, the period d of the scattering body is made sufficiently smaller than one period of the wavelength, and the diameter 2a when the radius of the scattering body is a is set. The size should be as close to the period d as possible. Then, the other scatterers and sensors are not arranged between each scatterer and each sensor, and a sufficient line-of-sight between each scatterer and each sensor is secured.

(2-1) Arrangement of scatterers The direct wave component represents a component of the incoming wave that is directly received by the sensor without being scattered by the scatterer. This component corresponds to the offset of the scattering pattern of the incoming wave. Therefore, for example, the fluctuation range of the signal intensity of the electric signal of the scattering pattern including the direct wave is 5000 to 10000 [W / m ² ], and the direct wave component of this scattering pattern is 5000 [W / m ² ]. In this case, it can be seen that when these can be ideally set to 0 [W / m ² ], the contrast of the scattering pattern becomes large in terms of db.

In order to reduce the direct wave of the scattering pattern, it is necessary to increase the density of the arrangement of the scatterer, which is sufficiently short for the shortest wavelength (high frequency) in the wavelength band of the incoming wave to be visualized. By arranging the scatterers at an arrangement period (eg, one tenth of the shortest wavelength), which is an arrangement interval, the direct wave component of the scattering pattern can be reduced. As a result, the contrast of the scattering pattern can be increased.

FIG. 7 is a diagram showing an example of an analysis model related to acquisition of the scattered electromagnetic field distribution when the parameters of the scatterer are changed.
In the example shown in FIG. 7, the dimensions of the analysis model are 10 [mm] in the x-axis direction, 90 [mm] in the y-axis direction, and 100 [mm] in the z-axis direction.
The material of the reference model of the scatterer is, for example, a conductor (silver), the radius of the scatterer is 2 [mm], the height of the scatterer is 5 [mm], and the scatterer is in the x and y directions. The period d of the sequence is 10 [mm].

An example of the analysis conditions (1 set) in this example is shown below.
(A) Incident angle: Φ = 15, 30, 45, 60 [°]
(B) Frequency band: 0.5 to 6 [GHz]
(C) Plane of electric field distribution to be confirmed: x-z plane, yz plane (d) Change parameter of radius of scatterer: 0.5 to 4 [mm]
(E) Change parameter of the period of the scatterer: 10 to 12 [mm]

FIG. 8 is a diagram showing an example of the contrast characteristic of the scattering pattern of the incoming wave with respect to the change in the arrangement period of the scatterer.
FIG. 8 shows an example of the contrast characteristics of the scattering pattern of the incoming wave when the frequency band under the analysis conditions of the model shown in FIG. 7 is 5 [GHz] and the incident angle is 45 [°]. FIG. 8A shows the contrast characteristics when the period d of the scatterer array is 10 [mm] under the analysis conditions of the model, and FIG. 8B shows the contrast characteristics when the period d is 11 [mm]. The contrast characteristics are shown in FIG. 8C, respectively, when the period d is 12 [mm].

FIG. 8 shows that the smaller the period of the arrangement of the scatterers under the analysis conditions of the model, the larger the contrast of the scattering pattern of the incoming wave.
As described above, in (2-1), by making the period of the scatterer sufficiently smaller than the wavelength, the density of the scatterer can be increased and the direct wave component of the scattering pattern can be reduced.

(2-2) Particle size of scatterer The electromagnetic field intensity (scattered wave intensity) radiated from the scatterer in Rayleigh scattering is generally expressed by the following equation (14).

However, k _s is the intensity of the scattered wave, N is the number of scatterers, m is the reflectance coefficient, D is the particle size of the scatterers, and λ is the wavelength of the electromagnetic wave.
That is, in order to increase the intensity of the scattered wave, the particle size D of the scatterer may be qualitatively increased.

Considering the above constraint (2-1), the particle size and arrangement of the scatterers are substantially equal to the arrangement period of the plurality of scatterers, for example, 90% or more of the particle size with respect to the arrangement period. Should be determined respectively.

FIG. 9 is a diagram showing an example of the contrast of the scattering pattern of the incoming wave with respect to the change in the radius of the scatterer.
FIG. 9 shows an example of the contrast characteristics of the scattering pattern of the incoming wave when the frequency band under the analysis conditions of the model shown in FIG. 7 is 5 [GHz] and the incident angle is 45 [°]. FIG. 9A shows the contrast characteristics when the radius r of the scatterer is 0.5 [mm] under the analysis conditions of the model, and FIG. 9B shows the contrast characteristics when the radius r is 2 [mm]. The contrast characteristics are shown in FIG. 9C, respectively, when the radius r is 4 [mm].

In FIG. 9, by setting the diameter of the scatterer of the array under the analysis conditions of the model to a size close to the period of the scattering pattern, the contrast of the scattering pattern of the incoming wave can be increased, and the intensity of the scattered wave can be increased. be able to.

(2-3) Between the sensor and the scatterer Even when the scatterers are arranged according to (2-1) and (2-2) above, another is between each sensor and each scatterer. In the presence of scatterers or sensors, secondary scattering occurs frequently. As a result, there is a problem that the signal itself is attenuated, the simultaneous equations finally obtained become complicated, and the amount of calculation increases. Therefore, in order to suppress secondary scattering and maintain signal linearity as much as possible, another scatterer or sensor is not arranged between each sensor and each scatterer, and between each sensor and each scatterer. A structure that secures the outlook for is desirable.

Outline of (3-1) and (3-2) When the theoretical model shown in FIG. 4 is followed, the amount of information per sensor obtained from the incoming wave changes depending on the number of sensors arranged in the receiving unit 13 and the arrangement method. It is thought that. It is desirable that a large amount of information can be obtained with high accuracy as easily as possible from the received signal pattern.

The condition for obtaining a large amount of information with high accuracy from the received signal pattern with as little calculation amount as possible is that (b1) the characteristics of the scattering pattern of the incoming wave are sufficiently received with respect to the sensor arrangement, (b2) calculation. It is replaced by reducing the amount as much as possible, (b3) covering the scattering pattern of the incoming wave for more frequencies.

In particular, the above (b1) and (b2) relate to the number of sensor arrangements, and (b3) relates to the sensor arrangement method. In the following (3-1), the number of sensor arrangements ((b1) and (b2)) will be described, and in the following (3-2), the sensor arrangement method (b3) will be described.

(3-1) Number of sensor arrangements The above condition (b1) is solved by "arranging a sufficient number of sensors", and the above condition (b2) is "minimize the number of sensors required". It is solved by "doing", but these are in a trade-off relationship.

From the above relationship, it is necessary to satisfy the condition that "the amount of information is large and the amount of calculation is small" as the optimum condition. For example, a state in which a sufficient amount of information is obtained is defined as "a state in which peaks or valleys and nodes of the scattering pattern of the incoming wave are received", and a state in which the amount of calculation is small is defined as "a state in which the number of sensors used is small". Define.

FIG. 10 is a diagram showing an example of a correspondence relationship between the amount of information, the amount of calculation, and the number of sensor arrangements.
In FIG. 10A, the arrangement of the sensors with respect to the scattering pattern is in a state where “the amount of calculation is small and the amount of information obtained is also small”, and in FIG. 10B, “the amount of information obtained is large but the amount of calculation is small”. In FIG. 10C, a state of "a large amount" is shown, and a state of "a small amount of calculation and a large amount of information that can be obtained" is shown.

As shown in FIG. 10, it can be seen that the optimum number of sensors can be determined if the period of the scattering pattern of the incoming wave is known according to the frequency of the incoming wave. However, depending on the sensor arrangement method, there are cases where a sufficient amount of information cannot be obtained even with the same number of sensors. Therefore, the number of sensors needs to be determined in consideration of the arrangement method.

(3-2) Sensor Arrangement Method FIG. 11 is a diagram showing an example of changes in the amount of information and the amount of calculation with respect to the same sensor arrangement position. In FIG. 11, under the condition of the same sensor arrangement, the frequency of the scattering pattern is A [GHz], the state of “the amount of calculation is small and the amount of information obtained is large”, and the frequency of the scattering pattern is B [GHz]. (> A [GHz]) indicates a state in which "the amount of calculation is small and the amount of information obtained is also small".

FIG. 12 is a diagram showing a specific example of sensor arrangement.
In FIG. 12, under the condition that 10 sensors (= 2 × d) are arranged in one cycle of the scattering pattern, the frequency of the scattering pattern is C [GHz] and the frequency of the scattering pattern is D, which is the highest value. The states of [GHz] (> C [GHz]) are shown respectively.

The above condition (b3) indicates that, as shown in FIG. 11, there is an event that "even if the sensors have the same arrangement, the amount of information that can be obtained differs depending on the scattering pattern for each frequency". .. Therefore, it is necessary to consider a method for guaranteeing that a sufficient amount of information can be obtained for as many frequencies as possible.

First, the reference interval p is set according to the amount of information obtained, based on the period d (see FIG. 12) of the scattering pattern of the electromagnetic wave having the shortest wavelength (highest frequency) in the frequency band to be visualized. .. For example, when five sensors are arranged in a length corresponding to the shortest wavelength described above, the reference interval p can be obtained as d / 5.

The method of determining the reference interval p is reduced to the method of grasping the peaks, valleys, and nodes of the scattering pattern, and how often the information in the vicinity of these can be sampled.
After that, a minute amount δ is set so that “0 <nδ <p”, and the position of each sensor is set to ± nδ (n = 0, n = 0, from the reference line (reference arrangement position) of the shortest wavelength period described above. 1, 2, ...) Are displaced and arranged at positions that satisfy the conditions.

At this time, the arrangement positions of the sensors are shifted from each other so that the values of ± nδ at the arrangement positions of the arranged sensors do not overlap, that is, the arrangement positions do not overlap. Further, n is a value satisfying "the maximum integer of the number of sensors arranged in the length corresponding to the period d x (1/2) or less".
In the case of the above example, since the number of sensors arranged in the length corresponding to the period d is 5, n is the maximum integer of 2.5 (= 5/2) or less, that is, 2.

As a result, the array of sensors has both periodicity and irregularity due to sparse density at the same time, so that the sensor can acquire some detailed information and overall rough information, respectively, and various frequencies of the scattering pattern can be obtained. On the other hand, the amount of information will be guaranteed as little as possible.

(Effects produced by one embodiment of the present invention)
As described above, according to the embodiment of the present invention, the frequency and arrival direction of a wide band electromagnetic wave can be measured in a short time without the trouble of scanning scan or the like without limiting to either radio wave noise or electromagnetic noise. It can be estimated with high accuracy.

When one embodiment of the present invention is applied to a radio wave environment, if the frequency band is limited to a narrow band such as Wi-Fi, it is possible to estimate the ease of communication connection for each channel and each location. Further, when one embodiment of the present invention is used in a wide band frequency band, the optimum installation location of the access point can be determined by estimating the radio wave environment when installing an access point for wide area wireless communication such as LTE / 5G. Can be identified.

Further, when one embodiment of the present invention is applied to an electromagnetic environment, the direction and frequency of arrival of the incoming wave can be quickly specified, so that the cause of noise failure in the communication device can be efficiently identified. In the past, advanced engineers used antennas and probes to investigate the direction of arrival of incoming waves for each frequency based on empirical rules, and then identified the cause of communication device failure. It took time and effort. On the other hand, in the present embodiment, the cause of failure can be easily identified in a short time without requiring advanced technology.

In addition, although the usage is different, when the input is used as the transmission signal from the array antenna and the output is used as the reception signal of the array antenna as a problem to solve the arrangement state of the scatterer, it is buried in the ground as an application. It is possible to estimate the location of unexploded bullets or land mines (corresponding to the scatterer array as the position of the problem to be solved).

The present invention is not limited to the above embodiment, and can be variously modified at the implementation stage without departing from the gist thereof. In addition, each embodiment may be carried out in combination as appropriate, and in that case, the combined effect can be obtained. Further, the above-described embodiment includes various inventions, and various inventions can be extracted by a combination selected from a plurality of disclosed constituent requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the problem can be solved and the effect is obtained, the configuration in which the constituent requirements are deleted can be extracted as an invention.

10 ... Wideband arrival wave information visualization device, 11 ... Radio wave separation unit, 12 ... Waveguide unit, 13 ... Receiver unit, 14 ... Signal processing unit.

Claims (3)

A radio wave separator that separates the incoming wave to form a scattered wave by a scatterer consisting of a dielectric or a conductor whose frequency and incident angle are arranged at intervals shorter than the shortest wavelength of the incoming wave to be visualized.
A waveguide composed of a connected conductor or dielectric and transmitting a scattered wave formed by the radio wave separating portion, and a waveguide.
A receiving unit that receives scattered waves transmitted by the waveguide by a plurality of sensors each arranged at intervals shorter than the shortest wavelength and converted into an electric signal.
The frequency of the incoming wave is performed by performing signal processing that solves the inverse problem when the signal strength of the electric signal converted by the receiving unit and the position of the sensor are used as outputs and the frequency and incident angle of the incoming wave are input. And a signal processing unit that estimates the combination of incident angles,
Electromagnetic wave information visualization device equipped with. The scatterer has a particle size at which the intensity of the scattered wave becomes a desired intensity.
The other scatterer or the sensor is arranged at a position different from the line segment connecting the arbitrary scatterer and the arbitrary sensor.
The electromagnetic wave information visualization device according to claim 1. A plurality of the sensors are arranged over a length corresponding to the period of the scattered wave based on the arrival wave having the highest frequency, which is the target of the visualization.
When the reference interval formed by equal division by the number of sequences of the sensors in the cycle is p, the maximum integer less than half the number of sequences in the cycle is n, and the minute amount is δ. The minute amount is determined so that 0 <nδ <p.
The plurality of sensors are arranged so that the arrangement positions do not overlap, and are arranged at positions that satisfy the condition of n times the minute amount from the reference position in the cycle.
The electromagnetic wave information visualization device according to claim 1 or 2.

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