JP2015022693A - Analysis method, analyzer, and analysis program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce use memory in a FDTD method.SOLUTION: An analytic space is divided into a plurality of cells, and an electromagnetic field in the analytic space is analyzed by a FDTD method. In the analysis method, permittivity of a medium of each cell is stored in a storage form whose amount of use memory is smaller than the real number of the permittivity. The storage form is an index value corresponding to the kind of the medium. In the calculation by the FDTD method, the permittivity stored by the index value is used by replacing with a real number corresponding to the index value. Alternatively, the storage form is a character variable allocated according to the kind of the medium. The real number of the permittivity corresponding to the character variable is substituted for the character variable in a mathematical formula showing calculation results of the FDTD method.

Description

  The present invention relates to an analysis technique for analyzing an electromagnetic field in an analysis space.

  In recent years, a method of analyzing an electromagnetic field using a FDTD (Finite Difference Time Domain method) method which is a finite difference method in a time domain has been proposed. The FDTD method is applied in an analysis space divided into cells. The FDTD method is executed by discretizing the entire analysis space to be calculated into voxels having a size corresponding to the frequency at which the calculation is performed. When performing electromagnetic field simulation such as radio wave propagation characteristics analysis using the FDTD method, the radio wave source (for example, antenna) and the surrounding environment placed in the analysis space are reproduced with a small rectangular parallelepiped block (Yee cell). It is necessary to construct a voxel model (see, for example, Non-Patent Document 1).

FIG. 9 is a flowchart showing a processing flow of an electromagnetic field analysis method using a conventional FDTD method. A conventional electromagnetic field analysis method will be described with reference to FIG. This electromagnetic field analysis method is executed by a control unit such as a CPU (Central Processing Unit) in the analysis apparatus.
First, the control unit defines an array (S901). Next, the analysis device defines the details of the analysis space by receiving an input of a three-dimensional absolute coordinate value (S902). This gives the x-, y-, and z-axis coordinates to the analysis space. Next, a dielectric constant as a medium parameter is assigned to the array of discrete points in the space given the coordinate values (S903). For example, if the medium filling the space of interest is air, the dielectric constant is ε _1. If the medium filling the space of interest is glass, the dielectric constant is ε _2. If the medium filling the space of interest is polypropylene, the dielectric constant is ε ₃ . Assign as follows. Next, the control unit generates a voxel model for FDTD calculation (S904). Next, the control unit calculates an electromagnetic field component (S905). Specifically, the electric and magnetic fields are determined by expanding Maxwell's equations into differential equations in the space and time domains and performing sequential calculations. Next, the control unit calculates an absorption boundary condition for the electromagnetic field component (S906). Next, the control unit determines whether all calculations have been completed (S907). If the calculation is not completed as a result of the determination, the process returns to S905. If the calculation is completed, the process proceeds to S908. Next, the control unit determines whether to perform recalculation by changing the material, that is, the medium (S908). As a result of the determination, if the material change is not completed, that is, if the material change and the corresponding recalculation are necessary, the control unit returns to the processing of S903, while the material change is completed, that is, no recalculation is required. If so, the control unit ends all the processes.

M. Omiya et al. "Design of Cavity-Backed Slot Antennas Using the Finite-Difference Time-Domain Technique," IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 46 (12): 1853-1858, (1998)

  In order to calculate the electromagnetic field component by the FDTD method, it is necessary to construct a voxel model as described above. For this purpose, the analysis apparatus or the analysis program needs to discretize the entire analysis space and set a dielectric constant value for each coordinate. As a result, there has been a problem that a large amount of resident memory has to be prepared in order to execute the analysis process. For example, in order to estimate the propagation characteristics of a radiated electromagnetic field component from a transmission wave source placed in a vehicle or office environment using the FDTD method, a huge amount of memory is required.

  In view of the above circumstances, an object of the present invention is to provide an analysis method, an analysis apparatus, and an analysis program that can reduce the memory used in the FDTD method.

  One aspect of the present invention is an analysis method in which an analysis space is divided into a plurality of cells, and an electromagnetic field in the analysis space is analyzed by a FDTD (Finite Difference Time-Domain method) method. Is stored in a storage form that uses less memory than the real value of the dielectric constant.

  In one aspect of the present invention, the storage form is an index value corresponding to the type of the medium, and the dielectric constant stored as the index value is used as the index value in the calculation of the FDTD method. Replace with the corresponding real value.

  In one aspect of the present invention, the storage form is a character variable assigned according to the type of the medium, and the character variable in the mathematical expression indicating the calculation result of the FDTD method is assigned to the character variable. Substitute the corresponding real value of dielectric constant.

  One embodiment of the present invention is an analysis apparatus that divides an analysis space into a plurality of cells and analyzes an electromagnetic field in the analysis space by an FDTD (Finite Difference Time-Domain method) method. A storage unit is provided that stores the permittivity in a storage form that uses less memory than the real value of the permittivity.

  One embodiment of the present invention is an analysis program for causing a computer to execute the above analysis method.

  According to the present invention, the memory used in the FDTD method can be reduced.

It is a figure which shows the structure of the analyzer which concerns on one Embodiment of this invention. It is a figure which shows the flow of preparation of a voxel model. It is a figure which compares the conventional dielectric constant memory | storage method and the dielectric constant memory | storage method of Embodiment 1. FIG. It is a flowchart which shows the flow of the electromagnetic field analysis process by an analyzer. It is a flowchart which shows the flow of the process which produces sequence data. It is a figure which compares the conventional dielectric constant memory | storage method and the dielectric constant memory | storage method of Embodiment 2. FIG. It is a flowchart which shows the flow of the electromagnetic field analysis process by an analyzer. It is a figure which shows the mode of calculating the difference from the example of the propagation characteristic for every different model, and each propagation characteristic. It is a flowchart which shows the flow of a process of the electromagnetic field analysis method using the conventional FDTD method.

[Embodiment 1]
FIG. 1 is a block diagram showing a configuration of an analysis apparatus 100 according to an embodiment of the present invention. The analysis device 100 includes a control unit 10, an FDTD calculation unit 11, an analysis space information memory 12 (storage unit), a voxel storage memory 13, and a medium constant holding memory 14. The control unit 10 controls the operation of the entire analysis apparatus 100. The FDTD calculator 11 executes various FDTD calculation processes. The FDTD calculation unit 11 includes an electric field component calculation unit 11a, an electric field component absorption boundary condition calculation unit 11b, a magnetic field component calculation unit 11c, and a magnetic field component absorption boundary condition calculation unit 11d. The analysis space information memory 12 is a memory that stores the configuration of the analysis space together with information on the coordinate system. The analysis space information memory 12 also stores the value of the dielectric constant at each point on the analysis space. In the present embodiment, the value of the dielectric constant at each point on the analysis space is not a real number format, has a smaller memory usage, and is an integer index value (1, 2,...) Associated with the type of medium. , N) in the analysis spatial information memory 12. The voxel model storage memory 13 stores information on the constructed voxel model. The medium constant holding memory 14 stores a dielectric constant as a real value associated with each index value for each medium type.

  FIG. 2 is a diagram showing a flow of creating a voxel model. For example, if the vehicle is to be voxel modeled, the structure is measured to design the voxel model, and the voxel model is developed on the simulator. In this state, the calculation of the electromagnetic field by the FDTD method is executed, and if it is necessary to recalculate by changing the medium of the analysis space, the processing from the design of the voxel model is repeated again.

FIG. 3 is a diagram comparing the conventional dielectric constant storage method and the dielectric constant storage method of the present embodiment. Conventionally, as shown on the left side of FIG. 3, the three-dimensional array of dielectric constants W (i, j, k) in the analysis space uses a double precision real data type, and the medium is air. When the medium is glass, ε ₁ is stored in a real number format including a decimal point, such as ε ₂ . i, j, and k are all natural numbers. As described above, in the conventional dielectric constant storage method, the dielectric constant of a large number of cells is stored by handling a large number of double-precision real number data, so that the amount of memory used becomes extremely large. On the other hand, in the dielectric constant storage method according to the present embodiment, as shown on the right side of FIG. 3, instead of the actual dielectric constant value, index values (1, 2,... , N) is stored in the three-dimensional array W (i, j, k) using a single precision real type (including integer type) data type. For example, the index value “1” is stored in the analysis space information memory 12 when the medium is air, and the index value “2” is stored when the medium is glass. Then, when the value of the dielectric constant is required for the calculation of the electromagnetic field by the FDTD method, the real value (ε ₁ , ε ₂ ,..., Ε _n ) of the dielectric constant corresponding to the stored index value is obtained. Called from the medium constant holding memory 14 and used for calculation. As a result, it is possible to reduce the memory usage of the analysis spatial information memory 12 as compared with the prior art in which the dielectric constant consisting of a real value is associated with the discretized voxel coordinates on a one-to-one basis. In particular, as the number of cells used increases, the memory usage reduction effect according to the present embodiment increases.

FIG. 4 is a flowchart showing the flow of electromagnetic field analysis processing by the analysis apparatus 100. Details of the electromagnetic field analysis process will be described with reference to FIG.
First, the control unit 10 sets an analysis frequency (S101). Next, the control unit 10 automatically calculates the optimum cell size (S102). Here, the optimum cell size is calculated based on the analysis frequency set in S101. Calculation accuracy can be secured by sufficiently reducing the cell size from the wavelength size (corresponding to the analysis frequency). For example, the cell size is set to 1/10 of the wavelength. Next, the control unit 10 defines a medium index (S103). Specifically, the control unit 10 defines which index value corresponds to the dielectric constant of all types of media. For example, when the medium is air, the dielectric constant is associated with an index value “1”, and when the medium is glass, the dielectric constant is associated with an index value “2”.

Next, the control unit 10 creates array data (S104). FIG. 5 is a flowchart showing a flow of processing for creating array data by assigning a value to each array of the three-dimensional array W (i, j, k). The sequence data creation process will be described with reference to FIG.
First, the control unit 10 reads three-dimensional CAD data (3D-CAD data) that defines the structure of the analysis space (S1041). Next, the control unit 10 reads a medium variable (S1042). In the present embodiment, the medium variable is an index value (1, 2,..., N) corresponding to the type of medium. Next, the control unit 10 defines a data array of a three-dimensional array of dielectric constants W (i, j, k) in the analysis space (S1043). Next, the control unit 10 stores an index value corresponding to the type of medium in the three-dimensional array W (i, j, k) of dielectric constant (S1044). For example, when the medium is air, the index value “1” is stored as the dielectric constant, and when the medium is glass, the index value “2” is stored as the dielectric constant. Next, the control unit 10 determines whether or not the index value storage processing has been completed for all the three-dimensional arrays W (i, j, k) (S1045). If the result of determination is that index value storage processing has not been completed for all three-dimensional arrays W (i, j, k), the processing of S1044 is repeated while i, j, k are incremented by one each. As a result of the determination, if index value storage processing has been completed for all three-dimensional arrays W (i, j, k), it is assumed that creation of the three-dimensional array W (i, j, k) has been completed ( S1046).

  Returning to FIG. 4, when the creation of the array data is completed (S104), the control unit 10 converts the coordinate values (S105). In this coordinate value conversion process, the voxel data determined in S104 (the index value stored in the three-dimensional array W (i, j, k)) is arranged at a desired position in the analysis space in a desired direction. It is. The coordinate value conversion processing in S105 includes rotation and movement processing. The reason why such coordinate value conversion processing is necessary is to re-arrange the model at an appropriate position in the analysis space that secures the region of the absorption boundary layer necessary for the FDTD calculation. Next, the control unit 10 creates a voxel model for FDTD calculation (S106). Here, based on the optimum cell size automatically calculated in S102, the voxel model can be created by dividing the cell with the object boundary line in the analysis space according to the optimum cell size on the CAD data. Next, the control unit 10 calculates an electromagnetic field component in the analysis space based on the created voxel model (S107). Specifically, the control unit 10 develops Maxwell's equations into differential equations in the space / time domain and sequentially calculates them to determine the electric field / magnetic field. In this calculation, the dielectric constant value of the medium of each cell is used. For this dielectric constant value, the index value stored in W (i, j, k) is referred to on the analysis space information memory 12, and the real value of the dielectric constant corresponding to this index value is stored on the medium constant holding memory 14. Get by reading with. As a result, the analysis space information memory 12 does not store the real value of the dielectric constant, but stores only the index value corresponding to the medium, so that the memory usage can be reduced. In particular, the larger the number of cells used, the greater the memory reduction effect according to this embodiment.

  Next, the control unit 10 calculates an absorption boundary condition for the electromagnetic field component (S108). The absorption boundary condition is a condition introduced when the electromagnetic field analysis is performed using the FDTD method, so that the electromagnetic wave that reaches the calculation region boundary is reflected, or is introduced near the boundary. Next, the control unit 10 determines whether or not all calculations have been completed (S109). If the calculation is not completed, the process returns to S107. If the calculation is completed, all processes are terminated.

  As described above, the analysis method by the analysis apparatus 100 includes the step of storing the dielectric constant of the medium for each cell as an index value corresponding to the type of medium, which uses less memory than the real value of the dielectric constant. doing. The above analysis method by the analysis apparatus 100 is used by replacing the dielectric constant stored in the index value with a real value corresponding to the index value in the calculation of the FDTD method.

[Embodiment 2]
Next, another embodiment of the present invention will be described. In the configuration of the analysis apparatus 100 ′ according to the present embodiment, the control unit 10, the analysis space information memory 12, and the medium constant holding memory 14 are respectively the control unit 10 ′, the analysis space information memory 12 ′, and the medium constant holding memory 14. The configuration is the same as that shown in FIG.

  The control unit 10 ′ controls the overall operation of the analysis apparatus 100 ′. The analysis space information memory 12 'is a memory that stores the configuration of the analysis space together with information on the coordinate system. The analysis space information memory 12 'also stores the value of the dielectric constant at each point on the analysis space. In the present embodiment, the value of the dielectric constant at each point on the analysis space is not in the real number format, but has a smaller memory usage, and the analysis space information memory 12 ′ is in the form of a character variable associated with the type of medium. Is remembered. The medium constant holding memory 14 'stores a dielectric constant as a real value to be substituted for each character variable for each medium type.

FIG. 6 is a diagram comparing the conventional dielectric constant storage method and the dielectric constant storage method of the present embodiment. Conventionally, as shown on the left side of FIG. 6, the three-dimensional array of dielectric constants W (i, j, k) in the analysis space uses constants, ε ₁ when the medium is air, and the medium is glass. in the case of as epsilon _2, it has stored the value of the dielectric constant in real format including a decimal point. i, j, and k are all natural numbers. In the conventional dielectric constant storage method, since a large number of dielectric constant values are stored in a real number format including a decimal point, the amount of memory used is extremely large. In contrast, in the dielectric constant storage method of the present embodiment, as shown on the right side of FIG. 6, instead of the actual dielectric constant value, character variables (x1, x2, assigned according to the type of medium) are assigned. .., Xn) are stored in the analysis space information memory 12 as a three-dimensional array of dielectric constants W (i, j, k) in the analysis space. For example, the character variable “x1” is stored as the dielectric constant when the medium is air, and the character variable “x2” is stored as the dielectric constant when the medium is glass. As a result, the calculation result of the electromagnetic field by the FDTD method is obtained in the form of an equation including the character variables (x1, x2,..., Xn). In this embodiment, the real values (x1 = ε _{1_1} , x2 = ε _{1_2} ,..., X1) of the dielectric constant of the medium are added to the character variables (x1, x2 _,. = Ε 1 — _n ) is substituted to obtain a final electromagnetic field calculation result.
As a result, it is possible to reduce the memory usage of the analysis spatial information memory 12 ′ as compared with the conventional technique in which the dielectric constant consisting of real values is associated with the discretized voxel coordinates on a one-to-one basis. In particular, the larger the number of cells used, the greater the memory reduction effect according to this embodiment.

The calculation result of the propagation characteristics of the electromagnetic field varies depending on the material of the structure existing in the analysis space. In the prior art, even if the model is the same, if it is desired to obtain the calculation result of the propagation characteristics when the material of the structure is changed, it is necessary to perform complicated recalculation each time. On the other hand, in this embodiment, the calculation result of the electromagnetic field by the FDTD method is obtained in the form of a mathematical expression with the dielectric constant as a variable. Therefore, even if the dielectric constant of the medium for each cell is changed to a different value, the calculation result of the electromagnetic field by the FDTD method can be immediately obtained as a numerical value simply by substituting the new dielectric constant value into the above formula. It is done. In FIG. 6, a set of dielectric constants described as “model 1 dielectric constant”, “model 2 dielectric constant”,..., “Model n dielectric constant” is the medium change as described above (model 1 → model 2 → -> Shows the combinations of dielectric constants that should be substituted into the above equation when applying model n). For example, if it is desired to calculate the electromagnetic field when the structure of the analysis space is changed from the material of model 1 to the material of model n due to a design change, a set of dielectric constants to be substituted into the above equation (x1 = ε _{1_1, x2 = ε 1_2, ···} , x1 = ε 1_n) from _{(x1 = ε n_1, x2 =} ε n_2, ···, may be changed to x1 = ε _{n_n).}

FIG. 7 is a flowchart showing the flow of electromagnetic field analysis processing by the analysis apparatus 100 ′. Details of the electromagnetic field analysis processing will be described with reference to FIG.
First, the control unit 10 ′ sets an analysis frequency (S201). Next, the control unit 10 ′ automatically calculates the optimum cell size (S202). Here, the optimum cell size is calculated based on the analysis frequency set in S201. Calculation accuracy can be secured by sufficiently reducing the cell size from the wavelength size (corresponding to the analysis frequency). For example, the cell size is set to 1/10 of the wavelength. Next, the control unit 10 ′ defines a medium variable (S203). Specifically, it is defined which character variable corresponds to the dielectric constant of all types of media. For example, when the medium is air, the character variable “x1” is associated with the dielectric constant, and when the medium is glass, the character variable “x2” is associated with the dielectric constant. Next, the control unit 10 ′ creates array data (S204). Regarding the array data creation processing, except that the index values (1, 2,..., N) of the first embodiment are replaced with character variables (x1, x2,..., Xn) in the present embodiment. This is the same as the description of FIG. According to the present embodiment, the analysis space information memory 12 ′ does not store real-value dielectric constants, but only stores character variables corresponding to the medium of each cell, so that the memory usage can be reduced. it can.

  When the creation of the array data is completed, the control unit 10 'converts the coordinate value (S205). This coordinate value conversion process includes rotation and movement processes. The reason why such coordinate value conversion processing is necessary is to re-arrange the model at an appropriate position in the analysis space that secures the region of the absorption boundary layer necessary for the FDTD calculation. Next, the control unit 10 creates a voxel model for FDTD calculation (S206). Based on the optimum cell size automatically calculated in S202, the voxel model can be created by dividing the cell with the object boundary line of the analysis space according to the optimum cell size on the CAD data. Next, the control unit 10 calculates an electromagnetic field component in the analysis space based on the created voxel model (S207). Specifically, the control unit 10 develops Maxwell's equations into differential equations in the space / time domain and sequentially calculates them to determine the electric field / magnetic field. This calculation result is obtained in the form of an equation including the character variables (x1, x2,..., Xn).

Next, the control unit 10 ′ calculates an absorption boundary condition for the electromagnetic field component (S208). The meaning of the absorption boundary condition is the same as described above. Next, the control unit 10 ′ determines whether or not all calculations have been completed (S209). If the calculation is not completed as a result of the determination in S209, an inquiry is made as to whether or not to perform further calculation by changing the frequency (S210), and if there is a need to change the frequency, the process returns to S201. If it is not necessary to change the process, the process returns to S207. The reason for returning to the processing of S201 when the frequency needs to be changed is that the “frequency setting” (S201) and “automatic cell size automatic calculation” (S202) need to be executed again in accordance with the change of the calculation model. Because. As a result of the determination in S209, if the calculation is completed, the control unit 10 ′ uses the real value of the dielectric constant of the medium (x1 = ε _{1_1} , x2 = ε _{1_2,.} x1 = ε 1 — _n ) is substituted (S211). Next, the control unit 10 ′ determines whether or not to change the material, that is, the medium filling each cell (S212). As a result of the determination in S212, if the material change is not completed, that is, if the material change is necessary, the process returns to S211 and a new dielectric constant combination (for example, x1 = ε _{2_1) is added to the} character variable in the above formula. , X2 = ε _{2_2} ,..., _X1 = ε 2 — _n ). If the result of determination in S212 is that the material change has been completed, the control unit 10 ′ terminates all the processes.

  According to the analysis apparatus 100 ′ of the present embodiment, the calculation result of the electromagnetic field by the FDTD method is obtained in the form of a mathematical expression including the dielectric constant as a variable. Therefore, combinations of different values of the dielectric constant of the medium (model 1, model 2,..., Even when the model n) is changed, the calculation result of the electromagnetic field by the FDTD method is immediately obtained as a numerical value simply by substituting a new dielectric constant value into the above formula.

  In particular, in electromagnetic field simulation, the effect of a simulation model is often compared with a difference from free space propagation characteristics, or a difference due to the presence or absence of a structure is often evaluated. According to the present embodiment, the difference calculation can be performed by simply calculating the propagation characteristics for each model by simply substituting the value of the dielectric constant for each model into the above formula. FIG. 8 is a diagram illustrating an example of propagation characteristics for different models and how to calculate a difference from each propagation characteristic. As shown in the figure, since the free space loss value corresponds to the case where there is no structure, the relationship of x1 = x2 =.

  As described above, the analysis method by the analysis apparatus 100 ′ stores the dielectric constant of the medium for each cell as a character variable assigned according to the type of the medium, which uses less memory than the real value of the dielectric constant. Have a stage to do. The above analysis method performed by the analysis apparatus 100 ′ substitutes the real value of the dielectric constant corresponding to the character variable for the character variable in the mathematical expression indicating the calculation result of the FDTD method.

数式（１）において、εは誘電率、μは透磁率を示している。 The numerical example of the calculation result by the FDTD method about an electric field and a magnetic field is shown. Although there are six components of x, y, and z for the electric field and the magnetic field, the following formula (1) representatively shows an electric field component _Ex in the x direction and a magnetic field component Hx in the _x direction.

In Expression (1), ε represents a dielectric constant, and μ represents a magnetic permeability.

  The analysis method executed by the analysis apparatuses 100 and 100 ′ is an analysis method in which the analysis space is divided into a plurality of cells and the electromagnetic field in the analysis space is analyzed by the FDTD method. The analysis method executed by the analysis apparatuses 100 and 100 ′ includes a step of storing the dielectric constant of the medium for each cell in a storage form in which the memory usage is smaller than the real value of the dielectric constant.

  According to the analysis apparatuses 100 and 100 ′ described above, the memory used in the FDTD method can be reduced. Further, according to the analysis apparatus 100 ′, recalculation of electromagnetic field analysis can be easily executed with a small calculation amount even when the material in the analysis space is changed.

  In the above description, the form in which the dielectric constant of the substance in the analysis space is stored as an index value or a character variable is shown. However, when a magnetic material is handled in the analysis space, not only the dielectric constant of the substance in the analysis space but also the magnetic permeability has a spatial distribution. In such a case, not only the dielectric constant of the substance in the analysis space but also the magnetic permeability is handled in the same manner as the dielectric constants of [Embodiment 1] and [Embodiment 2], so that the actual permeability can be realized. You may memorize | store as a memory | storage form (index value or a character variable) with less memory usage than a numerical value. In this way, the memory usage can be further reduced when the magnetic material is handled in the analysis space.

  1 is recorded in a computer-readable recording medium, and the program recorded in the recording medium is read into a computer system and executed to perform analysis processing. Also good. The “computer system” here includes an OS (Operating System) and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible disk, a magneto-optical disk, a portable medium such as a ROM (Read Only Memory) and a CD-ROM, and a hard disk incorporated in a computer system. Say. Furthermore, “computer-readable recording medium” refers to a fixed volatile memory such as a volatile memory inside a computer system serving as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. Including those holding time programs.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes a design that does not depart from the gist of the present invention. Needless to say, the above-described embodiment and a plurality of modifications can be combined within a range in which the contents do not conflict with each other. Further, in the above-described embodiments and modifications, the structure of each part has been specifically described, but the structure and the like can be changed in various ways within a range that satisfies the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Control part, 10 '... Control part, 11 ... FDTD calculation part, 11a ... Electric field component calculation part, 11b ... Electric field component absorption boundary condition calculation part, 11c ... Magnetic field component calculation part, 11d ... Magnetic field component absorption boundary condition calculation part 12 ... Analysis spatial information memory (storage unit), 12 '... Analysis spatial information memory (storage unit), 13 ... Voxel storage memory, 14 ... Medium constant holding memory, 14' ... Medium constant holding memory, 100 ... Analyzing device, 100 '... Analysis device

Claims (5)

In the analysis method of dividing the analysis space into a plurality of cells and analyzing the electromagnetic field in the analysis space by the FDTD (Finite Difference Time-Domain method) method,
An analysis method including a step of storing a dielectric constant of a medium for each cell in a storage form in which a memory usage is smaller than a real value of the dielectric constant. The storage form is an index value corresponding to the type of the medium,
The analysis method according to claim 1, wherein in the calculation of the FDTD method, the dielectric constant stored in the index value is used by replacing it with a real value corresponding to the index value. The storage form is a character variable assigned according to the type of the medium,
The analysis method according to claim 1, wherein a real value of a dielectric constant corresponding to the character variable is substituted for the character variable in the mathematical expression indicating the calculation result of the FDTD method. In the analysis device that divides the analysis space into a plurality of cells and analyzes the electromagnetic field in the analysis space by the FDTD (Finite Difference Time-Domain method) method,
An analysis apparatus including a storage unit that stores a dielectric constant of a medium for each cell in a storage form in which a memory usage is smaller than a real value of the dielectric constant. On the computer,
The analysis program for performing the analysis method of any one of Claim 1 to 3.

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