Electromagnetic field intensity calculating device

An electromagnetic field intensity calculating device simulates the intensity of the electromagnetic field generated by an electric circuit, and performs a required simulation process at a high speed. That is, the electromagnetic field intensity calculating device simulates the electromagnetic field intensity generated by an object electric circuit device by processing an object frequency generated by the object electric circuit device. The electromagnetic field intensity calculating device comprises a calculating unit for calculating the resonant frequency of the object electric circuit device and a retrieving unit for retrieving from a plurality of object frequencies a harmonic frequency of a wave source approximate to the resonant frequency calculated by the calculating unit so that the electromagnetic field intensity can be simulated on the frequency retrieved by the retrieving unit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an electromagnetic field intensity 
calculating device for simulating the intensity of the electromagnetic 
field generated by an electric circuit, and more specifically to an 
electromagnetic field intensity calculating device for performing a 
required simulation process at a high speed. 
2. Description of the Prior Art 
A lot of electric devices are commonly used these days. They include power 
devices which consume a large amount of electric power, and various kinds 
of electronic devices. Particularly, the power devices generate strong 
undesired electric waves. Even the electronic devices generate the 
undesired electric waves from their built-in circuit elements such as 
transformers, power transistors, etc. Since the undesired electric waves 
generated by the electric circuit devices (electric devices) interfere 
other electric waves such as radio, television, etc., there have been 
strict restrictions placed in many countries. 
Various countermeasures such as shielding technology, filtering technology, 
etc. are required to meet these restrictions on the electric waves. These 
countermeasures need quantitative simulation to prove how the electric 
waves can be reduced, and the simulation process should be performed at a 
high speed. 
The electromagnetic field intensity of an object can be simulated by 
obtaining the electric current in each point of the object and 
substituting the obtained current in a well-known logical expression of 
the generation of electric waves. A moment method is a typical simulation 
process. It is one of the integral equations derived from the Maxwell 
electromagnetic wave equation for use in calculating the electronic 
current in each element of an object after dividing the object into small 
elements. In the electromagnetic field intensity calculating device 
according to the moment method, the simulation is performed with the 
frequency of a generated electromagnetic wave properly assumed (assumed 
are the basic frequency of the wave source of an object and its harmonic 
frequency). 
Since it takes a long time to analyze all frequencies, the operator 
selects, in the conventional methods, some frequencies to be analyzed to 
perform simulation on the selected frequencies and then further select the 
frequencies to perform simulation around suspect frequencies. 
However, with the configuration in which the electromagnetic field 
intensity is calculated on the frequencies selected by the operator, the 
electromagnetic field intensity can be calculated only on the selected 
frequencies, which may not include the worst frequency, and the most 
suspect frequency can be unfortunately missed. To prevent this, all 
frequencies should be completely analyzed with an unpractically long time 
consumed. 
SUMMARY OF THE INVENTION 
The present invention aims at providing a new electromagnetic field 
intensity calculating device for performing a simulation process on the 
required electromagnetic field intensity at a high speed. 
According to the present invention, the electromagnetic field intensity of 
the frequency of the electric wave generated by an object electric circuit 
device is calculated based on the moment method, etc. By outputting the 
structure information of the electric circuit device, the resonant 
frequency of the electric circuit device can be calculated and that 
harmonics frequency of the wave source frequency which is generated by the 
object electric device and is approximate to the calculated resonant 
frequency can be retrieved, to provide the object frequency whose 
electromagnetic field intensity is to be measured, and based on which the 
electromagnetic field intensity of the electric circuit device can be 
calculated. These processes allow the simulation of the electromagnetic 
field intensity to be performed only on the electric magnetic wave having 
the frequency that is possibly generated by the electric circuit device 
and the intensity of the electromagnetic wave generated from the object 
electric device is possibly at maximum, thereby quickly measuring the 
electromagnetic field intensity. 
The calculation of the resonant frequency is made by the above described 
calculating process based on the input impedance of the circuit in the 
electric circuit device; the physical dimension of the aperture of the 
structure of the electric circuit device; the outer dimension of the 
structure of the electric circuit device; the length of the cable of the 
electric circuit device; or the intervals of connection points in the 
structure of the electric circuit device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is described in detail by referring to the 
embodiments. 
FIG. 1 shows the principle of the present invention. In FIG. 1, an 
electromagnetic field intensity calculating device 1 calculates the 
electromagnetic field intensity of the electric circuit device to be 
analyzed according to the moment method, etc. 
The electromagnetic field intensity calculating device 1 comprises an input 
unit 2; an electromagnetic field intensity calculating unit 3; a first 
frequency memory unit 4; a second frequency memory unit 5; and a 
preprocessing unit 6. 
The input unit 2 inputs structure information about an object electric 
circuit device through a CAD system, etc. The electromagnetic field 
intensity calculating unit 3 receives from the input unit 2 the structure 
information about the object electric circuit device to calculate the 
electromagnetic field intensity of the frequency of the electric wave 
generated by the object electric circuit device based on the moment 
method, etc. when the frequency to be analyzed is provided. 
The first frequency memory unit 4 stores a frequency which can be generated 
by an object electric circuit device, i.e. a frequency of a wave source 
provided in the object electric circuit device and the harmonics thereof. 
The second frequency memory unit 5 stores an object frequency to be 
provided for the electromagnetic field intensity calculating unit 3. 
The preprocessing unit 6 comprises a calculating unit 8 for calculating the 
resonant frequency of the electric circuit device and a retrieving unit 7 
for determining and storing the frequency to be stored in the second 
frequency memory unit 5. 
Upon receipt of the structure information about the object electric circuit 
device from the input unit 2 according to the present invention, the 
resonance frequency calculating unit 8 calculates the resonant frequency 
of the electric circuit device. For example, the resonant frequency of the 
object electric circuit device can be calculated by obtaining the resonant 
frequency from the input impedance of the circuit of the electric circuit 
device, obtaining the resonant frequency from the physical dimensions of 
the aperture of the structure of the electric circuit device, obtaining 
the resonant frequency from the length of the cable of the electric 
circuit device, or obtaining the resonant frequency from the gap at the 
joint in the structure of the electric circuit device. 
As a result of the calculation of the resonant frequency, the retrieving 
unit 7 retrieves the harmonic frequency of the wave source approximate to 
the calculated resonant frequency of the frequencies stored in the first 
frequency memory unit 4, and stores it in the second frequency memory unit 
5. 
When the frequency is stored in the second frequency memory unit 5, the 
electromagnetic field intensity calculating unit 3 calculates the 
electromagnetic field intensity of the frequencies generated by the object 
electric circuit device using the frequency to be stored in the second 
frequency memory unit 5 as the object of the analysis. 
Thus, the electromagnetic field intensity calculating device 1 does not 
calculate the electromagnetic field intensity for all the frequencies 
stored in the first frequency memory unit 4, but selects only the 
frequency which generates a high electromagnetic field intensity level 
when it is a resonant frequency, calculates the electromagnetic field 
intensity of the selected frequencies, and successfully calculates the 
requested electromagnetic field intensity at a high speed. 
FIG. 2 shows the configuration of the electromagnetic field intensity 
calculating device 1 according to the present embodiment. In FIG. 2, the 
CPU 9 is a central processing device for controlling the entire system of 
the electromagnetic field intensity calculating device 1 according to the 
present embodiment, and functions based on the system program stored in 
the main memory 10. The main memory is connected to the CPU 9 through the 
bus A, and stores, in addition to the above described system program, a 
simulation program and a pre-process program described later. Outputting 
these programs to the CPU 9 allows the CPU 9 to perform corresponding 
processes. Therefore, together with the main memory 10, the CPU 9 also 
functions as preprocessing unit for performing the preprocess program. For 
example, it functions a resonant frequency calculating unit for 
calculating the resonant frequency according to the structure information 
about an object which is obtained from, for example, an input file. 
Together with the main memory 10, the CPU 9 also functions a calculated 
frequency retrieving unit for retrieving the calculated frequency 
according to the result calculated by the resonant frequency calculating 
unit. The CPU 9 also functions as electromagnetic field intensity 
calculating unit for performing the above described simulation program, 
and calculates the electromagnetic field intensity of the object according 
to the resonant frequency. 
Furthermore, main memory 10 comprises a resonant frequency memory for 
storing the result calculated by the resonant frequency calculating unit; 
a wave source frequency memory for storing predetermined wave source 
frequency; and calculated frequency memory for storing the result 
retrieved by the above described retrieving unit. 
The CPU 9 is also connected to the keyboard and display via the bus A, and 
selects and performs the simulation program and preprocess program. The 
display displays the process results obtained by the CPU 9 such as the 
data of the calculated frequency obtained by retrieval by the retrieving 
unit, the data, output to the output file described above, etc. 
An external storage device 11 is connected to the bus A. The external 
storage device 11 is, for example, an input file 12 or an output file 13. 
The input file 12 stores the structure information, that is, the data 
about an object, obtained as divided from an electric circuit device 
(object) to be processed by the electromagnetic field intensity 
calculating device 1 according to the present embodiment. For example, the 
data can be the outer dimensions and aperture of the object, cable length, 
etc. The output file 13 stores the calculation result from the 
electromagnetic field intensity calculating device 1 about the 
electromagnetic field intensity of the object. The calculation result is 
stored together with the frequency data. The external storage device can 
be a hard disc or a magnetic disc. 
FIG. 3 shows the relationships between the above described simulation 
program and preprocess program, and among the resonant frequency memory 
RAS, wave source frequency memory, and calculated frequency memory, 
including the input file 12 and output file 13. The electromagnetic field 
intensity calculating device 1 according to the present embodiment 
calculates the electromagnetic field intensity generated by an electronic 
device to be processed. As shown in FIG. 3, the output file 13 comprises 
the simulation program 14, wave source frequency memory 15, resonant 
frequency memory 16, calculated frequency memory 17, and preprocess 
program 18 to realize the present invention. When the simulation program 
14 receives the structure information obtained as divided from the object 
electric circuit device from the input file 12 and is given the frequency 
of the object, it calculates the electromagnetic field intensity of the 
frequency generated by the object electric circuit device according to the 
moment method. 
The wave source frequency memory 15 stores the basic frequency (from the 
input file 12) of the wave source of the object electric circuit device, 
and also stores its harmonic frequency. The resonant frequency memory 16 
stores the resonant frequency of the object electric circuit device. The 
calculated frequency memory 17 stores the object frequency to be provided 
for the simulation program 14. 
The preprocess program 18 calculates the resonant frequency of the object 
electric circuit device and stores it in the resonant frequency memory 16, 
and then calculates the object frequency to be provided for the simulation 
program 14 and stores it in the calculated frequency memory 17. 
Described below are the process performed by the simulation program 14 and 
then the process performed by the preprocess program 18. FIG. 4 shows an 
example of the flowchart of the process performed by the simulation 
program 14. 
When the simulation program 14 is activated, it first reads the divided 
structure information of the object electric circuit device from the input 
file 12 as shown in the flowchart shown in FIG. 4. Then, in step 2, it 
determines whether or not the process has been completed on all 
frequencies stored in the calculated frequency memory 17. If not, the 
simulation program 14 selects one of the unprocessed frequencies stored in 
the calculated frequency memory 17, and then calculates the wave length 
.lambda. of the selected frequency in step 3. 
Then, in step 4, one of the t unprocessed divided elements is selected to 
calculate the impedance Z.sup.o .sub.cc between divided metals; the 
impedance Z.sup.o .sub.cd and Z.sup.o .sub.dc between a divided metal and 
dielectric portion; the impedance Z.sup.o .sub.dd and Z.sup.d .sub.dd 
between divided dielectric portions; the admittance Y.sup.o .sub.dd and 
Y.sup.d .sub.dd between divided dielectric portions; the reactance B.sup.o 
.sub.cd and B.sup.o .sub.dc between a divided metal and dielectric 
portion; and the reactance B.sup.o .sub.dd and B.sup.d .sub.dd between 
divided dielectric portions. The superscript ".sup.o " indicates a value 
obtained in the atmosphere. The superscript ".sup.d " indicates a value 
obtained within a dielectric portion. The subscript ".sub.c " indicates a 
metal. The subscript ".sub.d " indicates a dielectric portion. The 
subscript ".sub.cc " indicates the correlation from a metal to a metal. 
The subscript ".sub.dd " indicates the correlation between a dielectric 
portion to a dielectric portion. The subscript ".sub.cd " indicates the 
correlation from a dielectric portion to a metal. The subscript ".sub.dc " 
indicates the correlation from a metal to a dielectric portion. 
When it is determined that a divided element is selected in step 4, another 
divided element is selected from the t divided elements as the pair 
processed in the impedance calculation, etc. in step 5. When it is 
determined that all divided elements have been selected in step 5, control 
is returned to step 4. If it is determined that an unprocessed divided 
element has been selected, control is then passed to step 6, the 
impedance, etc. (Z.sup.o .sub.cc, Z.sup.o .sub.cd, Z.sup.o .sub.dc, 
Z.sup.o .sub.dd, Z.sup.d .sub.dd, Y.sup.o .sub.dd, Y.sup.d .sub.dd, 
B.sup.o .sub.cd, B.sup.o .sub.dc, B.sup.o .sub.dd, and B.sup.d .sub.dd) 
between the two selected divided elements is calculated using the wave 
length .lambda. calculated in step 3, and control is returned to step 5. 
If it is determined that all divided elements have been selected in step 4, 
that is, if it is determined that the calculation has been completed on 
all impedance, etc., then control is passed to step 7 to use the 
calculated impedance, etc.; the wave source V read from the input file 12 
and driven at the frequency selected in step 2; the electric current 
I.sub.c in the divided metal elements; the equivalent electric current 
I.sub.d on the surface of the divided dielectric elements; and the 
equivalent electromagnetic current M on the surface of the divided 
dielectric elements to derive: 
the simultaneous equations produced according to the moment method under 
the boundary condition that the metal surface indicates the electric field 
value of 0 
EQU Z.sup.o .sub.cc !I.sub.c !+Z.sup.o .sub.cd !I.sub.d !+B.sup.o .sub.cd 
!M!=V!; 
the simultaneous equations produced according to the moment method under 
the boundary condition that the tangent components of the electric field 
are equal on either sides of the boundaries of the dielectric portion 
EQU Z.sup.o .sub.dc !I.sub.c !+Z.sup.o .sub.dd +Z.sup.d .sub.dd !I.sub.d 
!+B.sup.o .sub.dd +B.sup.d .sub.dd !M!=0!; 
and 
the simultaneous equations produced according to the moment method under 
the boundary condition that the tangent components of the electric field 
are equal on either sides of the boundaries of the dielectric portion 
EQU B.sup.o .sub.dc !I.sub.c !+B.sup.o .sub.dd +B.sup.d .sub.dd !I.sub.d 
!+-Y.sup.o .sub.dd -Y.sup.d .sub.dd !M!=0! 
Solving the simultaneous equations according to the moment method provides 
the electric current I.sub.c in the divided metal elements; the equivalent 
electric current I.sub.d on the surface of the divided dielectric 
elements; and the equivalent electromagnetic current M on surface of the 
divided dielectric elements. 
In step 8, it is determined by counting the processed observation points 
whether or not the process has been completed on all entered observation 
points. If yes, control is returned to step 2. If not, control is passed 
to step 9 and the electromagnetic field intensity brought by the 
calculated I.sub.c, I.sub.d, and M to the observation points is obtained 
by the given equation. The result is stored in the output file 13 and 
control is returned to step 8. 
Thus, the simulation program 14 receives the divided structure information 
about the object electric circuit device from the input file 12 and 
calculates according to the moment method the electromagnetic field 
intensity of the frequencies generated by the electric circuit device and 
stored in the calculated frequency memory 17. 
Described below is the process performed by the preprocess program 18. 
FIGS. 5 through 7 show an embodiment of the process performed by the 
preprocess program 18. Upon receipt of a request to calculate the 
electromagnetic field intensity, the preprocess program 18 reads the 
structure information about the object electric circuit device from the 
input file 12 in step 1 as shown in the flowchart shown in FIG. 5. Then, 
in step 2, the resonant frequency of the object electric circuit device is 
obtained and stored in the resonant frequency memory 16. In step 3, the 
object frequency (calculated frequency) to be processed by the simulation 
program 14 is obtained and stored in the calculated frequency memory 17. 
Finally, in step 4, the simulation program 14 is activated. 
FIG. 6 is a detailed flowchart of the process in step 2 shown in FIG. 5. 
FIG. 7 is a detailed flowchart of the process in step 3 shown in FIG. 5. 
That is, when the preprocess program 18 starts calculating the resonant 
frequency in step 2 in the flowchart shown in FIG. 5, it first sets the 
start frequency fl, stop frequency fn, and step frequency fs in step 1 as 
shown in the flowchart shown in FIG. 5. In step 2, the variable n is set 
to 1 and the object process frequency fz is set to fl. 
In step 3, a circuit pattern of the object electric circuit device is 
selected and the reactance of the selected circuit pattern is calculated. 
The obtained reactance value X (=X(n)) is stored in the reactance memory 
(omitted in FIG. 3) corresponding to the process frequency fz (=f(n)). In 
the calculation of the reactance, the impedance Zin viewed from the 
sending terminal to the terminating equipment is calculated by the 
following equation with the circuit pattern represented as an equivalent 
circuit of the terminal impedance Ze, characteristic impedance Zo, 
transmission constant .gamma. and pattern length 1. The imaginary part of 
the Zin is specified for the calculation. 
##EQU1## 
In step 4, it is determined whether or not the process frequency fz has 
reached the stop frequency fn. If not, control is passed to step 5 to 
update the process frequency fz and the variable n according to "fz=fz D 
fs and n=n+1". Then, control is returned to step 3. If the determination 
indicates "yes", that is, if the reactance calculation for the frequency 
areas fl through fn of the selected circuit pattern has been completed, 
control is passed to step 6, and the variables n and m are set to 1. The 
variable n indicates the entry number of the reactance memory, and the 
variable m indicates the entry number of the resonant frequency memory 16. 
In step 7, the reactance values X(n) and X(n+1) are read from the reactance 
memory to determine whether or not X(n)&lt;0 and X(n+1)&gt;0 are effective. If 
not, control is passed to step 8 and the variable m is updated according 
to "m=n+1". Then, control is returned to step 7. If the determination 
indicates "yes", that is, if the reactance value X(n+1) approximately 
indicating zero is obtained as a resonant point as shown in FIG. 8B, then 
control is passed to step 9 and the frequency f(n+1) corresponding to the 
reactance value X(n+1) is entered in the resonant frequency memory 16 
pointed to by the variable m (hereinafter, the entered frequency of the 
m-th entry of the resonant frequency memory 16 is represented by fk(m)). 
In step 10, it is determined whether or not the process has been completed 
on all circuit patterns of the object electric circuit device. If yes, the 
process terminates. If not, control is passed to step 11 and the variable 
m is updated according to M=m+1. The control is returned to step 2 to 
proceed with the next circuit pattern. 
Thus, if the preprocess program 18 has started the calculation of the 
resonant frequency in step 2 of the process shown in FIG. 5, it calculates 
the resonant frequencies of the object electric circuit device according 
to the flowchart shown in FIG. 6, and stores them in the resonant 
frequency memory 16. 
When the preprocess program 18 has started the calculation of the frequency 
in step 3 of the process shown in FIG. 5, it first sets the variable p to 
1 in step 1, and then sets the variable m to 1 in step 2. The variable m 
indicates the entry number of the resonant frequency memory 16 and the 
variable p indicates the entry number of the wave source frequency memory 
15. Hereinafter, the entry frequency of the p-th entry of the wave source 
frequency memory 15 is represented by f0(p). 
In step 3, the error value fw is set. It is determined whether or not the 
following equation is effective between the entry frequency fk(m) of the 
resonant frequency memory 16 and the entry frequency f0(p) of the wave 
source frequency memory 15 pointed to by the variable p. 
EQU f0(p)-fw.ltoreq.fk(m).ltoreq.f0(p)+fw 
As a result of the determination, it is determined whether or not the fk(m) 
matches the f0(p) in approximation. 
If the determination indicates non-coincidence in step 3, control is passed 
to step 4 to update the variable m according to "m=m+1". Then, control is 
returned to step 3. When the determination indicates coincidence, control 
is passed to step 5 and the frequency f0(p) matching the resonant 
frequency fk(m) is entered to the calculated frequency memory 17. In step 
6, it is determined whether or not the process has been completed on all 
frequencies entered in the wave source frequency memory 15. If yes, the 
process terminates. If not, control is passed to step 7 to update the 
variable p according to "P=P+1". Then, control is returned to step 2. 
When the preprocess program 18 starts calculating the frequency in step 3 
of the flowchart shown in FIG. 5, the object frequencies are obtained by 
the simulation program 14 according to the flowchart shown in FIG. 7, and 
are stored in the calculated frequency memory 17. 
As described above, the simulation program 14 calculates according to the 
moment method the electromagnetic field intensity of the frequencies 
generated by the object electric circuit device and stored by the 
calculated frequency memory 17. The preprocess program 18 selects one of 
the frequencies stored in the wave source frequency memory 15 (frequency 
which can be generated by the object electric circuit device) as matching 
the resonant frequency of the circuit pattern of the object electric 
circuit device, and stores it in the calculated frequency memory 23. 
That is, according to the present invention, all frequencies stored in the 
wave source frequency memory 15 are not processed in calculating the 
electromagnetic field intensity, but the electromagnetic field intensity 
of only the frequencies matching the resonant frequency is calculated. For 
example, when the object electric circuit device has a wave source driven 
at the basic frequency of 10 MHz, the wave source frequency memory 15 
stores the frequencies 10 MHz, 20 MHz, 30 MHz, 40 MHz, 50 MHz, . . . . 
However, the electromagnetic field intensity is not calculated for all the 
frequencies, but the frequencies matching the resonant frequency, that is, 
only the frequencies that may generate high electromagnetic field 
intensity, are processed in calculating the electromagnetic field 
intensity according to the present invention. 
If the object electric circuit device has different wave sources driven at 
different frequencies, the simulation program 14 performs a different 
simulation process for each wave source. For example, assuming that the 
object electric circuit device has circuit parts having the wave sources 
driven at the basic frequencies of 7 MHz and 10 MHz, the simulation 
process is performed by driving at 42 MHz the circuit part having the wave 
source driven at the basic frequency of 7 MHz when the resonant frequency 
is 42 MHz, and is performed by driving at 60 MHz the circuit part having 
the wave source driven at the basic frequency of 10 MHz when the resonant 
frequency is 60 MHz. 
According to the flowchart shown in FIG. 6, the preprocess program 18 
obtains the resonant frequency of the circuit pattern of the object 
electric circuit device to calculate the resonant frequency of the object 
electric circuit device. However, obtaining the resonant frequency through 
other structures can also be effective in obtaining the resonant frequency 
of the object electric circuit device. FIGS. 9A, 9B, 10A and 10B show 
examples of the structures. 
According to the flowchart in FIG. 9A, the preprocess program 18 obtains 
the resonant frequency regulated by the dimensions of the aperture of the 
object electric circuit device and stores it in the resonant frequency 
memory 16. That is, with the aperture shown in FIG. 11A, the resonant 
frequencies represented by the following equations are stored in the 
resonant frequency memory 16. C.sub.o in the equations indicates the 
velocity of light. 
##EQU2## 
According to the flowchart shown in FIG. 9B, the preprocess program 18 
obtains the resonant frequency regulated by the outer dimensions 
(including an internal device) of the object electric circuit device and 
stores it in the resonant frequency memory 16. That is, with the form 
shown by in FIG. 11B, the resonant frequencies represented by the 
following equations are stored in the resonant frequency memory 16. 
##EQU3## 
According to the flowchart shown in FIG. 10A, the preprocess program 18 
obtains the resonant frequency regulated by the length of the cable of the 
object electric circuit device, and stores it in the resonant frequency 
memory 16. That is, the resonant frequency represented by the following 
equation is generated from the form shown by in FIG. 11C. The obtained 
results are stored in the resonant frequency memory 16. 
##EQU4## 
According to the flowchart shown in FIG. 10B, the preprocess program 18 
obtains the resonant frequency regulated by the connection interval of the 
object electric circuit device, and stores it in the resonant frequency 
memory 16. That is, the resonant frequency represented by the following 
equation is generated from the connection interval shown in FIG. 11D. The 
obtained results are stored in the resonant frequency memory 16. 
##EQU5## 
These flowcharts shown in FIGS. 6, 9A, 9B, 10A and 10B can be combined to 
obtain the resonant frequency and store it in the resonant frequency 
memory 16. 
The present invention has been described above by referring to the attached 
drawings, but is not limited to these applications. For example, the 
present invention can be applied to the electromagnetic field intensity 
calculating device for calculating the electromagnetic field intensity 
based on other algorithms other than the moment method. 
As described above, the electromagnetic field intensity calculating device 
according to the present invention does not calculate the electromagnetic 
field intensity for all frequencies generated by an object electric 
circuit device, but calculates the electromagnetic field intensity on the 
frequency selected as possibly generating a large electromagnetic field 
intensity as a resonant frequency. Thus, the present invention can quickly 
calculate required electromagnetic field intensity.