JP2013205235A - System and method for evaluating radio wave reflection characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique appropriately evaluating radio wave reflection characteristics of an inner structure having an opening part on a fuselage surface at a low cost in a short period.SOLUTION: The radio wave reflection characteristic evaluation system includes a ray tracing unit 2, and a reflectivity calculation unit 3. The ray tracing unit 2 calculates a plurality of incident angles of each of a plurality of light beams at a plurality of reflection positions in the inner structure by a ray tracing method, on the basis of light beam data 21 relating to the plurality of light beams, and model data 22 relating to the inner structure having an opening part on a fuselage surface of a flying object. The reflectivity calculation unit 3 calculates a first reflectivity of the inner structure on the basis of the plurality of incident angles of each of the plurality of light beams and material characteristic data 23 on the reflection characteristics of the materials of the inner structure.

Description

  The present invention relates to a radio wave reflection characteristic evaluation system and a radio wave reflection characteristic evaluation method, and more particularly to a radio wave reflection characteristic evaluation system and a radio wave reflection characteristic evaluation method of a flying object.

  As flying bodies, those having stealth properties are known. In order to increase the stealth of the flying body, it is necessary to reduce the reflection of radio waves on the surface of the aircraft, as well as a duct (or air intake) provided from the opening on the surface of the aircraft toward the inside. It is also necessary to reduce the reflection of radio waves at the internal structure. For this purpose, it is necessary to appropriately evaluate the reflection characteristics of radio waves in designing and manufacturing the internal structure. A technique for appropriately evaluating the reflection characteristics of radio waves at the internal structure is desired.

  On the other hand, ray tracing is known as one method of simulation. Ray tracing is a calculation method that virtually simulates physical phenomena in the real world by tracking the propagation path of waves that mainly travel in a three-dimensional space. For example, when using rays as waves, ray tracing may be used as one of the techniques in the rendering process for drawing a three-dimensional computer graphics image.

  As a technique using ray tracing, International Publication WO2009 / 0669507 discloses a radio wave propagation simulator, a radio wave propagation characteristic estimation method used therefor, and a program therefor. This radio wave propagation simulator estimates a radio wave propagation state from a transmission point to a limited evaluation area in the space using a plurality of objects defined in the space. The radio wave propagation simulator includes an extraction unit, a selection unit, and an estimation unit. The extraction unit extracts a path reaching the evaluation area using a geometric optical propagation estimation method. The selection means selects an object using the path extracted by the extraction means and the geometric information of the evaluation area. The estimation means estimates a detailed radio wave propagation situation from the transmission point to the inside of the evaluation area using only the object selected by the selection means.

International Publication WO2009 / 069507

  As described above, in order to improve the stealth property of the flying body, it is necessary to reduce the reflection of radio waves at the internal structure (eg, duct) having an opening on the surface of the airframe. For this purpose, it is necessary to appropriately evaluate the reflection characteristics of radio waves in designing and manufacturing the internal structure. In that case, for example, a method is conceivable in which the internal structure is actually manufactured, and then the reflection characteristics of the radio waves in the internal structure are evaluated and improved as necessary. However, actually producing or improving the internal structure is costly and troublesome. There is a demand for a technique for appropriately evaluating the reflection characteristics of radio waves in a short period of time at a low cost without actually manufacturing the internal structure or suppressing the number of manufacturing as low as possible. There is also a need for a technique that can reduce the reflection of radio waves at the internal structure.

  An object of the present invention is to provide a technique for appropriately evaluating the reflection characteristics of radio waves in a short time at a low cost with respect to an internal structure having an opening on the surface of an airframe. Another object of the present invention is to provide a technique capable of reducing the reflection of radio waves with respect to the internal structure.

  These objects and other objects and benefits of the present invention can be easily confirmed by the following description and the accompanying drawings.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the embodiments for carrying out the invention. These numbers and symbols are added with parentheses in order to clarify the correspondence between the description of the claims and the mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

  The radio wave reflection characteristic evaluation system according to the first aspect of the present invention includes a ray tracing unit (2) and a reflectance calculation unit (3). The ray-tracing part (2) is a model related to a plurality of light rays (e1, e2,...) And an internal structure (51) having an opening (52) on the surface of the flying body (50). Based on the data (22), for each of the plurality of light rays (e1, e2,...), A plurality of incident angles (P11, P12,...) At a plurality of reflection positions (P11, P12,...) Within the internal structure (51). β1, β2,... are calculated by the ray tracing method. The reflectance calculation unit (3) includes a plurality of incident angles (β1, β2,...) Of each of the plurality of light beams (e1, e2,...) And material characteristic data relating to the reflection characteristics of the material of the internal structure (51). Based on (23), the first reflectance (R0) of the internal structure (51) is calculated.

  In the radio wave reflection characteristic evaluation system, the reflectance calculation unit (3) preferably includes each light beam reflectance calculation unit (11) and an internal structure reflectance calculation unit (12). In that case, each light reflectance calculation part (11) is based on several incident angle ((beta) 1, (beta) 2, ...) and material characteristic data (23) about each of several light rays (e1, e2, ...). Then, the second reflectance (R1) of the internal structure (51) is calculated. The internal structure reflectance calculator (12) calculates the first reflectance (R0) based on the plurality of second reflectances (R1) of the plurality of light rays (e1, e2,...).

  In the above-described radio wave reflection characteristic evaluation system, each light reflectance calculation unit (11) has a plurality of incident angles (β1, β2,...) From the material characteristic data (23) for each of a plurality of light rays (e1, e2,...). It is preferable to extract a plurality of material reflectivities (r11, r12,...) Corresponding to. Each light reflectance calculation unit (11) further calculates a product of a plurality of material reflectances (r11, r12,...) For each of a plurality of light rays (e1, e2,...) As a second reflectance (R1). It is preferable to calculate as The internal structure reflectance calculator (12) divides the sum of the plurality of second reflectances (R1) of the plurality of rays (e1, e2,...) By the number of the plurality of rays (e1, e2,...). It is preferable to calculate the value as the first reflectance (R0).

  The radio wave reflection characteristic evaluation system preferably further includes a material selection unit (13) and an optimum material determination unit (14). In this case, the material selection unit (13) selects one material as a selection material from the plurality of materials for the internal structure (51). Each light reflectance calculation unit (11) calculates a plurality of second reflectances (R1) based on the material characteristic data (23) regarding the reflection characteristics of the selected material. The internal structure reflectance calculator (12) calculates the first reflectance (R0) based on the plurality of second reflectances (R1) of the selected material. The optimum material determination unit (14) includes a material selection unit (13), a light reflectance calculation unit (11), and an internal structure reflectance calculation unit (12) among the plurality of materials for the internal structure (51). The material corresponding to the first reflectance (R0) having the lowest value among the plurality of first reflectances (R0) calculated by (1) is extracted as the optimum material.

  The radio wave reflection characteristic evaluation system preferably further includes a storage unit for storing the light ray data (21), the model data (22), and the material characteristic data (23).

  The radio wave reflection characteristic evaluation method according to the second aspect of the present invention includes a light beam data (21) relating to a plurality of light beams (e1, e2,...) And an internal portion having an opening (52) on the surface of the flying body (50). Based on the step (S01) of reading out the model data (22) related to the structure (51) from the storage unit (4), the ray data (21), and the model data (22), a plurality of rays (e1, e2) ,..., A plurality of incident angles (β1, β2,...) At a plurality of reflection positions (P11, P12,...) Within the internal structure (51) are calculated by the ray tracing method (S02). ), A step (S03) of reading out material characteristic data (23) relating to the reflection characteristic of the material of the internal structure (51) from the storage unit (4), and a plurality of light rays (e1, e2,...) Incident angle (β1 .beta.2, ... and), based on the material characteristic data (23), and a step (S04) of calculating a first reflectance of the inner structure (51) to (R0).

  In the radio wave reflection characteristic evaluation method, the step of calculating the first reflectance (R0) (S04) includes a plurality of incident angles (β1, β2,...) For each of the plurality of light beams (e1, e2,...). And the step (S11) of calculating the second reflectance (R1) of the internal structure (51) based on the material property data (23), and the plurality of second rays (e1, e2,...) It is preferable to include a step (S12) of calculating the first reflectance (R0) based on the two reflectances (R1).

  In the radio wave reflection characteristic evaluation method, the step of calculating the second reflectivity (R1) (S11) includes, for each of the plurality of light rays (e1, e2,...), A plurality of incident angles from the material characteristic data (23). Extracting a plurality of material reflectivities (r11, r12,...) Corresponding to (β1, β2,...), And a plurality of material reflectivities (r11, r2,. It is preferable to include a step of calculating the product of r12, ...) as the second reflectance (R1). In the step (S12) of calculating the first reflectance (R0), the sum of the plurality of second reflectances (R1) of the plurality of light rays (e1, e2,...) Is the sum of the plurality of light rays (e1, e2,...). It is preferable to include a step of calculating the value divided by the number as the first reflectance (R0).

  The radio wave reflection characteristic evaluation method preferably further includes a step (S13) of selecting one material as a selection material from a plurality of materials for the internal structure (51). In that case, the step (S11) of calculating the second reflectance (R1) calculates a plurality of second reflectances (R1) based on the material property data (23) relating to the reflection property of the selected material. The step (S12) of calculating the first reflectance (R0) calculates the first reflectance (R0) based on the plurality of second reflectances (R1) of the selected material. The radio wave reflection characteristic evaluation method includes a material selection unit (13), each light reflectance calculation unit (11), and an internal structure reflectance calculation unit (12) among a plurality of materials for the internal structure (51). ) Further includes a step (S07) of extracting a material corresponding to the first reflectance (R0) having the lowest value among the plurality of first reflectances (R0) calculated by (2) as an optimum material. Is preferred.

  A program according to a third aspect of the present invention causes a computer to execute the radio wave reflection characteristic evaluation method described in any of the above paragraphs.

  According to the present invention, it is possible to appropriately evaluate the reflection characteristics of radio waves in a short time at a low cost with respect to an internal structure having an opening on the surface of the airframe. Further, according to the present invention, it is possible to reduce the reflection of radio waves with respect to the internal structure.

FIG. 1 is a schematic diagram illustrating a configuration example of a flying object to be evaluated by the radio wave reflection characteristic evaluation system. FIG. 2 is a schematic diagram illustrating an example of a relationship between a duct and a light beam in the evaluation method of the radio wave reflection characteristic evaluation system. FIG. 3 is a block diagram showing a configuration example of the radio wave reflection characteristic evaluation system according to the first embodiment of the present invention. FIG. 4 is a schematic diagram illustrating an example of light rays. FIG. 5 is a flowchart showing the operation of the radio wave reflection characteristic evaluation system according to the first embodiment of the present invention. FIG. 6 is a schematic diagram showing an example of ray tracing in step S02 of FIG. FIG. 7 is a table showing the result of step S02 in FIG. FIG. 8 is a schematic diagram illustrating an example of the calculation of the second reflectance in step S11 of FIG. FIG. 9 is a block diagram showing a configuration example of a radio wave reflection characteristic evaluation system according to the second embodiment of the present invention. FIG. 10 is a flowchart showing the operation (radio wave reflection characteristic evaluation method) of the radio wave reflection characteristic evaluation system according to the second embodiment of the present invention.

  Hereinafter, embodiments of a radio wave reflection characteristic evaluation system and a radio wave reflection characteristic evaluation method of the present invention will be described with reference to the accompanying drawings.

(First embodiment)
A radio wave reflection characteristic evaluation system according to a first embodiment of the present invention will be described. The radio wave reflection characteristic evaluation system 1 is an information processing apparatus exemplified by a computer. We evaluate the reflection characteristics of radio waves of a flying object with stealth using an electromagnetic wave absorber. More specifically, the radio wave reflection characteristics of the internal structure having an opening on the surface of the flying body are evaluated by simulation. The radio wave reflection characteristic evaluation system 1 can appropriately evaluate the radio wave reflection characteristic at a low cost in a short time. However, the internal structure is not particularly limited as long as it has a structure having an opening on the surface of the flying body and extending from the opening to the inside so that radio waves can enter from the opening. In the present embodiment, a duct (air intake) will be described as an example of the internal structure.

  Here, the flying object to be evaluated of the radio wave reflection characteristic evaluation system 1 will be described. FIG. 1 is a schematic diagram showing a configuration example of a flying object to be evaluated. The flying body 50 includes a duct 51 as an internal structure having an opening 52 on the surface of the airframe. The flying body 50 moves toward the target by moving the engine using the air sucked from the duct 51. In the duct 51, no radio wave absorber is applied to the innermost engine entrance surface and spinner. Accordingly, the radio wave reflection characteristic evaluation system 1 does not consider the reflection (reflectance = 1). On the other hand, a radio wave absorber is applied to the other inner wall of the duct 51. Therefore, the radio wave reflection characteristic evaluation system 1 evaluates the reflection characteristic in consideration of the reflectance specific to the radio wave absorber. In the example of this figure, the duct 51 has a shape that gradually spreads toward the back. The radio wave reflection characteristic evaluation system 1 obtains the first reflectivity R0 of the duct 51 as a whole when a light beam E0 simulating radio waves is incident on the duct 51.

  Next, an outline of the evaluation method of the radio wave reflection characteristic evaluation system 1 will be described. FIG. 2 is a schematic diagram illustrating an example of a relationship between a duct and a light beam in the evaluation method. In the example of this figure, one light beam E 0 is incident on the duct 51. The light beam E0 is reflected at the positions P1 and P2 in the duct 51 for the first and second times, respectively. Subsequently, after being reflected at the innermost member (engine inlet surface and spinner) with a reflectance of 1.0, the third, fourth, fifth, sixth, and seventh positions at positions P3, P4, P5, P6, P7, and P8, respectively. , 8th reflection. And it is radiated | emitted outside as reflected light E1. At this time, the radio wave reflection characteristic evaluation system 1 calculates the positions P1 to P8, the incident angles β1 to β8 at each of these positions, and the reflectivity r1 to r8 specific to the electron absorber with respect to the incident angles β1 to β8. The reflectance R of the entire duct 51 is calculated.

  Hereinafter, the radio wave reflection characteristic evaluation system 1 according to the present embodiment will be described in detail.

The configuration of the radio wave reflection characteristic evaluation system 1 according to the present embodiment will be described.
FIG. 3 is a block diagram showing a configuration example of the radio wave reflection characteristic evaluation system according to the first embodiment of the present invention. The radio wave reflection characteristic evaluation system 1 is an information processing apparatus, and includes a CPU (Central Processing Unit), a storage device, an input device, an output device, and an interface (not shown). The CPU, the storage device, the input device, the output device, and the interface are connected to each other via a bus or a cable so that information (data) can be transmitted and received. The storage device is exemplified by a RAM (Random Access Memory), a ROM (Read Only Memory), and an HDD (Hard Disk Drive). The input device is exemplified by a keyboard and a mouse. The output device is exemplified by a display and a printer. The interface is connected to an external computer, a storage device, a storage medium reader, and the like so as to be capable of bidirectional communication.

  The CPU expands, for example, a computer program installed in the HDD from the storage medium via the interface in the RAM. The developed computer program is executed, and information processing of the computer program is realized while controlling hardware such as a storage device, an input device, and an output device as necessary. The storage device records a computer program and records information (data) used by the CPU and information (data) to be generated. The input device outputs information (data) generated by a user operation to a CPU or a storage device. The output device outputs information (data) generated by the CPU and information (data) of the storage device so that the user can recognize them.

  The radio wave reflection characteristic evaluation system 1 includes a storage unit 4, a ray tracing unit 2 as software (computer program), and a reflectance calculation unit 3.

  The storage unit 4 is a storage device, and stores data used for evaluation (simulation) performed by the radio wave reflection characteristic evaluation system 1. The data includes light ray data 21, internal structure model data 22, and material property data 23. However, these data may not be stored in the radio wave reflection characteristic evaluation system 1, may be acquired from an external storage device or information processing device via a network, or may be a CD-ROM or USB memory. You may install from a storage medium.

  The light ray data 21 is data relating to the light ray E0 used for the simulation. The rays simulate radio waves such as radar waves. The data includes the incident angle, the number of incident rays, and the incident position of the light beam with respect to the evaluation object such as the duct 51. However, the incident angle is exemplified by the angle of attack α with respect to the duct 51. The number of incidents is exemplified by the number of a plurality of light beams constituting the light beam E0. The incident position is exemplified by the positions of a plurality of light beams at the opening 52.

  FIG. 4 is a schematic diagram illustrating an example of light rays. In the example of this figure, the light beam E0 is composed of a plurality of light beams e1 to e30, and is incident on the opening 52 of the duct 51 at a predetermined angle (position) at an angle of attack α. In this case, the number of incident light rays is about 30. The light beam data 21 associates the angle of attack α (°) of the light beam with respect to the opening 52 of the duct 51 and the number of light beams e (the number is changed depending on the angle of attack α). The position (not shown) of the light ray e at the opening 52 may be set in advance or may be calculated from the number and angle of attack. The radio wave reflection characteristic evaluation system 1 individually calculates the reflectance for each of the plurality of light rays (examples: e1 to e30), and calculates the overall reflectance of the duct 51 using them.

  In the example of FIG. 4, a plurality of light beams e1 to e30 arranged one-dimensionally in the vertical direction in the vicinity of the opening 52 are used, but the present embodiment is not limited to this example. For example, a plurality of light beams e arranged two-dimensionally in the vertical and horizontal directions (cross section of the duct 51) in the vicinity of the opening 52 may be used.

  The internal structure model data 22 is data indicating a model of the three-dimensional structure of the duct 51 having the opening 52 on the surface of the flying body 50. The material property data 23 is data relating to the reflection property of the material of the duct 51. The material is exemplified by a radio wave absorber. The reflection characteristic of the material is exemplified by data relating to the relationship between the incident angle β of the radio wave and the reflectance r of the material.

  Based on the light ray data 21 and the internal structure model data 22, the ray tracing unit 2 performs a plurality of reflections in the duct 51 for each of a plurality of light rays e1, e2,. , P1, P2,... Are calculated. Further, a plurality of incident angles β1, β2,... At the plurality of reflection positions P1, P2,. However, the ray tracing unit 2 calculates the reflection position P and the incident angle β by a ray tracing method. The ray tracing method is a calculation method that virtually simulates a physical phenomenon in the real world by approximating a wave propagating in a three-dimensional space as a light ray and tracking its propagation path. For example, the trajectory (propagation path) in the duct 51 relating to the rays e1, e2,... (Waves) traveling inside the duct 51 (in the three-dimensional space), the straightness of the rays, the relationship between the incident angle and the reflection angle, etc. This is a calculation method for virtually simulating the reflection phenomenon (physical phenomenon) of each light ray inside the duct 51 by tracking using the physical law as described above. The ray tracing method is known as one of methods in a rendering process for drawing a three-dimensional computer graphics image, for example. This method can also be applied in this embodiment.

  The reflectance calculation unit 3 determines the duct 51 based on the plurality of incident angles β1, β2,... Of each of the plurality of rays e1, e2,. The first reflectivity R0 as a whole is calculated. The reflectance calculation unit 3 includes light ray reflectance calculation units 11 and an internal structure reflectance calculation unit 12.

  For each of the plurality of light rays e1, e2,..., Each light reflectance calculation unit 11 is based on a plurality of incident angles β1, β2,... And the reflection characteristics of the material of the duct 51 of the material property data 23. A second reflectance R1 of the duct 51 is calculated. That is, the second reflectance R1 is calculated for each of the plurality of light rays e1, e2,. The internal structure reflectance calculator 12 calculates the first reflectance R0 of the duct 51 as a whole based on the plurality of second reflectances R1 for the plurality of light rays e1, e2,.

An operation (radio wave reflection characteristic evaluation method) of the radio wave reflection characteristic evaluation system 1 according to the present embodiment will be described.
FIG. 5 is a flowchart showing the operation (radio wave reflection characteristic evaluation method) of the radio wave reflection characteristic evaluation system according to the first embodiment of the present invention.

  The ray tracing unit 2 reads the light beam data 21 and the internal structure model data 22 from the storage unit 4 (step S01). Next, the ray tracing unit 2 uses a plurality of reflection positions P1, P2 in the duct 51 for each of the plurality of light beams e1, e2,... Based on the light beam data 21 and the internal structure model data 22. , ... are calculated. Further, a plurality of incident angles β1, β2,... At the plurality of reflection positions P1, P2,... Are calculated by the ray tracing method (step S02).

  FIG. 6 is a schematic diagram showing an example of ray tracing in step S02 of FIG. In the example of this figure, ray tracing of the light ray e19 is shown among the plurality of light rays e1, e2,. The light ray e19 enters the duct 51 and is reflected for the first time at the position P11. The incident angle with respect to the inner wall at the position P11 is β11≈70 °. Subsequently, the light ray e19 is reflected for the second time at the position P12. The incident angle with respect to the inner wall at the position P12 is β12≈50 °. Next, the light ray e19 is reflected at the position P13 after the reflection at the engine entrance surface, and is reflected for the third time. The incident angle with respect to the inner wall at the position P13 is β13≈75 °. Thereafter, the light ray e19 is emitted from the opening 82 to the outside. At this time, the three-dimensional structure of the duct 51 is defined by the internal structure model data 22, and the position and direction at the opening 52 where the light beam e <b> 19 enters is defined by the light beam data 21. Based on these, the ray tracing unit 2 calculates the locus of the light ray e19 by the ray tracing method. That is, the incident positions β11, β12, and β13 at the reflection positions P11, P12, and P13 and the reflection positions are calculated. Similarly, the ray tracing unit 2 calculates the trajectory, that is, the reflection position P in the duct 51 and the incident angle β at the position P for all of the plurality of rays e1, e2,.

  FIG. 7 is a table showing the result of step S02 in FIG. In the table showing the result of step S02 in FIG. 5, each row represents the reflection for each range of incident angles β (0 to 5 °, 5 ° to 10 °,...) For each ray e (e1, e2,...). Shows the number of times. For example, the light ray e1 shown in the uppermost line indicates the following. There are four reflections where the incident angle β is in the range of 0-5 °. There are five reflections with an incident angle β in the range of 5-10 °. There are five reflections with an incident angle β in the range of 10-15 °. There are four reflections with an incident angle β in the range of 15-20 °. There are four reflections with an incident angle β in the range of 20-25 °. There are three reflections with an incident angle β in the range of 25-30 °. There are 8 reflections with an incident angle β in the range of 30 to 35 °. There are seven reflections with an incident angle β in the range of 35-40 °. There is one reflection in which the incident angle β is in the range of 40 to 45 °. There are two reflections with an incident angle β in the range of 55-60 °. There is one reflection with an incident angle β in the range of 65 to 70 °. There is one reflection with an incident angle β in the range of 75-80 °. There is one reflection in which the incident angle β is in the range of 85 to 90 °. The rightmost column indicates the reflection frequency (total number of reflections) N for each light beam e (e1, e2,...). In the example of this figure, the range of the incident angle β is in increments of 5 °. However, the present embodiment is not limited to 5 °, and may be made finer, for example.

  Here, for example, the correspondence between the light beam e19 in FIG. 6 and the table in FIG. 7 is as follows. However, FIG. 6 is reproduced in the table. The row (column) of the light ray e19 is indicated by a black frame in the table. Regarding the light ray e19, in FIG. 6, the incident angle β11 at the position P11 is about 70 °. Therefore, in the table of FIG. 7, “1” is described in the range where the incident angle β is 70 to 75 °. In FIG. 6, the incident angle β12 at the position P12 is about 50 °. Therefore, in the table of FIG. 7, “1” is described in the range where the incident angle β is 50 to 55 °. Further, in FIG. 6, the incident angle β13 at the position P13 is about 75 °. Therefore, in the table of FIG. 7, “1” is described in the range where the incident angle β is 75 to 80 °. Since the reflection of the light beam e19 occurs three times, the reflection frequency (the total number of reflections) N is 3. The same applies to the other light rays e (e1, e2,...).

  Next, the reflectance calculation unit 3 reads the material characteristic data 23 related to the reflection characteristics of the radio wave absorber of the duct 51 from the storage unit 4 (step S03). Based on the plurality of incident angles β of each of the plurality of light beams e1, e2,... And the material property data 23 regarding the reflection property of the radio wave absorber on the inner wall of the duct 51, the reflectance calculation unit 3 One reflectance R0 is calculated (step S04).

  In step S04, the following steps S11 and S12 are executed. First, each light beam reflectance calculation unit 11 of the reflectance calculation unit 3 has a plurality of incident angles β and a material characteristic related to the reflection characteristic of the radio wave absorber on the inner wall of the duct 51 for each of the plurality of light beams e1, e2,. Based on the data 23, the second reflectance R1 of the duct 51 is calculated (step S11).

FIG. 8 is a schematic diagram illustrating an example of the calculation of the second reflectance in step S11 of FIG. The graph of FIG. 8 shows the material characteristic data 23 regarding the reflection characteristic of the electromagnetic wave absorber on the inner wall. The vertical axis represents the reflectance r, and the horizontal axis represents the incident angle β (°). A curve Q indicates the reflection characteristic of the radio wave absorber on the inner wall. In the example of this figure, the light beam e19 will be described. In the light ray e19, the incident angle β11 at the position P11 is about 70 °. Therefore, from the graph of FIG. 8, the reflectance r11 at the position P11 is about 0.15. The incident angle β12 at the position P12 is about 50 °. Therefore, from the graph of FIG. 8, the reflectance r12 at the position P12 is about 0.4. Further, the incident angle β13 at the position P13 is about 75 °. Therefore, from the graph of FIG. 8, the reflectance r13 at the position P13 is about 0.1. From the above, the second reflectance R1 _e19 of the light ray _e19 is
R1 _e19 = 0.15 × 0.4 × 0.1 = 0.006
It becomes.

Thus, in step S11, the light _{e i,} calculating a second reflectance _{R1 ei} by the following equation.
R1 ei _{= 1} time reflectance × 2 th reflectance of the reflectance × ... × N-th of However, N represents a reflection frequency of the light beam e _i. Then, for all rays _{e i,} to calculate the second reflectance _{R1 ei.} For example, if the number of light rays e is 30, second reflectances R1 _{e1 to} R1 _e30 are calculated for the light rays _{e1 to} e30, respectively.

Next, the internal structure reflectance calculator 12 of the reflectance calculator 3 is based on the plurality of second reflectances R1 _e1 , R1 _e2 ,... Of the plurality of rays e1, e2,. Is calculated (step S12). That is, the first reflectance R0 is calculated by the following formula.
R0 = (sum of the second reflectivity R1 _ei ) / total number of rays, ie
R0 = (second reflectance R1 _ei + second reflectance R1 _e2 +...) / Total number of rays. For example, if the number of rays e is 30,
R0 = (second reflectance R1 _e1 + second reflectance R1 _e2 +... + Second reflectance R1 _e30 ) / 30
It is. In the example results in FIG.
R0 = (5 × 10 ⁻¹¹ + 3 × 10 ⁻⁹ +...) / 30
≒ 0.01
It is. In dB notation,
R0 = -20log (0.01)
= 40 [dB]
It becomes. As described above, in step S12, the first reflectance R0 is calculated as the reflectance of the duct 51 regarding the light ray E0 (the bundle of light rays e1, e2,...).

  The reflectance calculation unit 3 stores the first reflectance R0 calculated in step S12 in the storage unit 4 as the reflectance of the duct 51 related to the light ray E0 (step S05).

  As described above, the radio wave reflection characteristic evaluation system 1 according to the present embodiment operates.

  According to the present embodiment, the reflectance (first reflectance R0) can be obtained by simulation by inputting predetermined data regarding an internal structure such as a duct having an opening on the surface of the body. That is, according to the present embodiment, it is possible to appropriately evaluate the reflection characteristics of radio waves in a short time at a low cost with respect to an internal structure such as a duct having an opening on the airframe surface.

(Second Embodiment)
A radio wave reflection characteristic evaluation system according to a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that a material selection unit 13 and an optimum material determination unit 14 are added to the radio wave reflection characteristic evaluation system. Hereinafter, the difference will be mainly described.

The configuration of the radio wave reflection characteristic evaluation system 1 according to the present embodiment will be described.
FIG. 9 is a block diagram showing a configuration example of a radio wave reflection characteristic evaluation system according to the second embodiment of the present invention. The radio wave reflection characteristic evaluation system 1 further includes a material selection unit 13 and an optimum material determination unit 14 as software (computer program) in addition to the radio wave reflection characteristic evaluation system 1 (FIG. 3) of the first embodiment. ing.

The material selection unit 13 selects one radio wave absorber from a plurality of radio wave absorbers for the duct 51. At this time, the material characteristic data 23 stores data relating to the reflection characteristics of the plurality of radio wave absorbers. For example, the material selection unit 13 can select one radio wave absorber from a plurality of radio wave absorbers stored in the material property data 23. In this case, the reflectance calculation unit 3 performs the same operation as that of the first embodiment for the selected radio wave absorber. That is, for each of the plurality of light beams e1, e2,..., Each of the light beam reflectance calculation units 11 and the reflection characteristics of the selected radio wave absorber in the material property data 23 are displayed. Based on, the second reflectance R1 _ei at the selected radio wave absorber is calculated. Next, the internal structure reflectance calculation unit 12 calculates the first reflectance R0 based on the plurality of second reflectances R1 _ei at the selected radio wave absorber for the plurality of light rays e1, e2,. calculate. Subsequently, the material selection unit 13 selects another radio wave absorber from the plurality of radio wave absorbers for the duct 51. The reflectance calculation unit 3 performs the same operation as that of the first embodiment again for the other selected radio wave absorbers. In this way, the material selection unit 13 and the reflectance calculation unit 3 calculate the first reflectance R0 for each of the plurality of radio wave absorbers for the duct 51. The optimum material determination unit 14 selects the first lowest value among the plurality of first reflectances R0 calculated by the material selection unit 13 and the reflectance calculation unit 3 from among the plurality of radio wave absorbers for the duct 51. The radio wave absorber corresponding to the reflectance R0 is extracted as the optimum material.

An operation (radio wave reflection characteristic evaluation method) of the radio wave reflection characteristic evaluation system 1 according to the present embodiment will be described.
FIG. 10 is a flowchart showing the operation (radio wave reflection characteristic evaluation method) of the radio wave reflection characteristic evaluation system according to the second embodiment of the present invention.

  Steps S01 and S02 are the same as those in the first embodiment.

  The material selection unit 13 refers to the material property data 23 and selects one radio wave absorber from a plurality of radio wave absorbers for the duct 51 (step S13). Subsequently, the operations of Step S03, Step S04, and Step S05 similar to those in the first embodiment are performed on the selected radio wave absorber. Then, the first reflectance R0 is calculated for the selected radio wave absorber. Similarly, the first reflectance R0 is calculated for all of the plurality of radio wave absorbers for the duct 51 (step S06). That is, a plurality of first reflectances R0 are calculated corresponding to a plurality of radio wave absorbers. Thereafter, the optimum material determination unit 14 selects the optimum radio wave absorber corresponding to the first reflectance R0 having the lowest value among the plurality of first reflectances R0 from among the plurality of radio wave absorbers for the duct 51. Extract as a material (step S07). The optimal material determination unit 14 stores the radio wave absorber extracted in step S07 in the storage unit 4 as the optimal radio wave absorber of the duct 51 related to the light beam E0 (step S08).

  As described above, the radio wave reflection characteristic evaluation system 1 according to the present embodiment operates.

  Note that in step S07, as the optimum radio wave absorber, the first reflectance R0 may not necessarily be the lowest value, provided that the first reflectance R0 is within a desired reflectance range. Also good.

  According to this embodiment, a radio wave absorber having a minimum reflectance (first reflectance R0) is extracted by simulation by inputting predetermined data regarding an internal structure such as a duct having an opening on the surface of the airframe. can do. That is, according to the present embodiment, it is possible to reduce the reflection of radio waves with respect to an internal structure such as a duct having an opening on the surface of the body.

  The ray tracing unit 2, the reflectance calculation unit 3, each light reflectance calculation unit 11, the internal structure reflectance calculation unit 12, the material selection unit 13, and the optimum material determination unit 14 are software (computer program) and hardware. It may be comprised with hardware, and may be comprised only with hardware.

  The software (computer program) of the present invention may be recorded on a computer-readable storage medium and read from the storage medium into an information processing apparatus as a radio wave reflection characteristic evaluation system.

  The present invention is not limited to the embodiments described above, and it is obvious that the embodiments can be appropriately modified or changed within the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 Radio wave reflection characteristic evaluation system 2 Ray tracing part 3 Reflectivity calculation part 4 Memory | storage part 11 Each light reflectivity calculation part 12 Internal structure reflectance calculation part 13 Material selection part 14 Optimal material determination part 21 Ray data 22 Internal structure model Data 23 Material property data 50 Flying object 51 Duct 52 Opening

Claims (10)

Based on the light ray data relating to the plurality of light rays and the model data relating to the internal structure having an opening on the surface of the flying body, a plurality of light rays at a plurality of reflection positions in the internal structure are obtained for each of the light rays. A ray-tracing unit that calculates the incident angle of the beam by the ray-tracing method,
A reflectance calculation unit that calculates a first reflectance of the internal structure based on the plurality of incident angles of each of the plurality of light rays and material characteristic data relating to a reflection characteristic of a material of the internal structure; Equipped with a radio wave reflection characteristic evaluation system. In the radio wave reflection characteristic evaluation system according to claim 1,
The reflectance calculator is
For each of the plurality of light rays, each light reflectance calculation unit that calculates a second reflectance of the internal structure based on the plurality of incident angles and the material property data;
An electromagnetic wave reflection characteristic evaluation system comprising: an internal structure reflectance calculation unit that calculates the first reflectance based on the plurality of second reflectances of the plurality of light rays. In the radio wave reflection characteristic evaluation system according to claim 2,
Each of the light reflectance calculators is
For each of the plurality of light rays, extract a plurality of material reflectivities corresponding to the plurality of incident angles from the material property data,
For each of the plurality of light rays, a product of the plurality of material reflectances is calculated as the second reflectance,
The internal structure reflectance calculator is
A radio wave reflection characteristic evaluation system that calculates, as the first reflectance, a value obtained by dividing the sum of the plurality of second reflectances of the plurality of light beams by the number of the plurality of light beams. In the radio wave reflection characteristic evaluation system according to claim 2 or 3,
A material selection unit that selects one material as a selection material from the plurality of materials for the internal structure;
Each of the light reflectance calculation units calculates the plurality of second reflectances based on material characteristic data relating to the reflection characteristics of the selected material,
The internal structure reflectance calculation unit calculates the first reflectance based on the plurality of second reflectances of the selected material,
Among the plurality of materials for the internal structure, the lowest of the plurality of first reflectances calculated by the material selection unit, each light reflectance calculation unit, and the internal structure reflectance calculation unit An electromagnetic wave reflection characteristic evaluation system further comprising an optimum material determination unit that extracts a material corresponding to the first reflectance having a value of 1 as an optimum material. In the radio wave reflection characteristic evaluation system according to any one of claims 1 to 4,
A radio wave reflection characteristic evaluation system further comprising a storage unit for storing the light ray data, the model data, and the material characteristic data. A step of reading out from the storage unit light ray data relating to a plurality of light rays and model data relating to an internal structure having an opening on the surface of the flying body;
Based on the ray data and the model data, for each of the rays, calculating a plurality of incident angles at a plurality of reflection positions in the internal structure by a ray tracing method;
Reading out material property data relating to the reflective properties of the material of the internal structure from the storage unit;
A radio wave reflection characteristic evaluation method comprising: calculating a first reflectance of the internal structure based on the plurality of incident angles of each of the plurality of light beams and the material characteristic data. In the radio wave reflection characteristic evaluation method according to claim 6,
The step of calculating the first reflectance includes
For each of the plurality of light rays, calculating a second reflectance of the internal structure based on the plurality of incident angles and the material property data;
Calculating the first reflectivity based on the plurality of second reflectivities of the plurality of light rays. The radio wave reflection characteristic evaluation method according to claim 7,
The step of calculating the second reflectance includes
Extracting a plurality of material reflectivities corresponding to the plurality of incident angles from the material property data for each of the plurality of light rays;
Calculating a product of the plurality of material reflectances as the second reflectance for each of the plurality of light rays, and
The step of calculating the first reflectance includes
A radio wave reflection characteristic evaluation method, comprising: calculating a value obtained by dividing a sum of the plurality of second reflectances of the plurality of light beams by a number of the plurality of light beams as the first reflectance. In the radio wave reflection characteristic evaluation method according to claim 7 or 8,
Selecting a material as a selection material from a plurality of materials for the internal structure,
The step of calculating the second reflectance calculates the plurality of second reflectances based on material property data relating to the reflection property of the selected material,
The step of calculating the first reflectance calculates the first reflectance based on the plurality of second reflectances of the selected material,
Among the plurality of materials for the internal structure, the lowest of the plurality of first reflectances calculated by the material selection unit, each light reflectance calculation unit, and the internal structure reflectance calculation unit A method for evaluating radio wave reflection characteristics, further comprising: extracting a material corresponding to the first reflectance having a value of 1 as an optimum material.   The program which makes a computer perform the radio wave reflection characteristic evaluation method as described in any one of Claims 6 thru | or 9.

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