JP7236717B2 - Antenna coil design method and its program - Google Patents

Description

The present invention relates to wireless power supply, and more particularly to antenna coil design technology.

Wireless power transmission can be broadly classified into a near-field type and a far-field type. The near-field type is a method of transmitting power by connecting the power transmitting side and the power receiving side via a magnetic field or an electric field, and it is possible to transmit a large amount of power with high efficiency, but the transmission distance is short. On the other hand, the far-field type is a method of receiving power by capturing and rectifying the energy emitted as electromagnetic waves with an antenna, and although long-distance transmission is possible, the transmission efficiency is low.

When power is supplied to home electric appliances, smartphones, and electric vehicles, relatively large power of several tens of W to several kW is required, so near-field systems such as electromagnetic induction or magnetic resonance coupling are used.

As for the electromagnetic induction type, in 2008, the Wireless Power Consortium (WPC), an industry group that formulates international standards, was launched, and in 2010, Qi, which is the first international standard for contactless power supply, was formulated. Initially, the standard was designed to support low power of 5 W or less, but in 2015, a standard supporting up to 15 W was enacted. Also, at present, AirFuelAlliance, a standardization organization following WPC, has established a maximum 50W standard. However, the electromagnetic induction type has a characteristic that the transmission distance is limited to several centimeters and is vulnerable to positional deviation, so it is more meaningful as a contactless power supply terminal rather than as a wireless power transmission.

On the other hand, the magnetic resonance coupling type has features such as medium-range and high-efficiency transmission, resistance to misalignment, and simple extension of the transmission distance using a repeater coil, solving the problems of the electromagnetic induction type. .

A magnetic resonance coupling type wireless force transmission system was announced by a research group at the Massachusetts Institute of Technology in 2007, and has achieved a transmission efficiency of 50% or more at a distance of 1 to 2 m (Non-Patent Document 1). Here, the basic principle of the magnetic resonance coupling type will be described. FIG. 1 is a block diagram of a magnetic resonance coupling type wireless power feeding system. The wireless power supply system 2 includes a power transmitter 10 and a power receiver 20 . A relay that relays power may be provided between the power transmitting device 10 and the power receiving device 20 .

The power transmission device 10 includes a power transmission coil L _TX , a resonance capacitor C _TX and a drive circuit 12 . The drive circuit 12 generates a magnetic field by exciting an alternating current through the coil _LTX on the power transmission side, and the magnetic field is taken in by the power receiving coil _LRX to induce a current, similar to the principle of the electromagnetic induction method. transmit power.

The power receiving device 20 includes a power receiving coil L _RX , a resonance capacitor C _RX and a load 22 . The load 22 includes, for example, a rectifier circuit that rectifies the AC current flowing through the power receiving coil _LRX .

Resonance-coupling type wireless power transmission resonates a near-field electromagnetic field in a transmitting/receiving resonator to transmit energy. In particular, the magnetic resonance coupling type that resonates the magnetic field has characteristics such as medium-range and high-efficiency transmission, resistance to positional deviation, and simple extension of the transmission distance using a repeater coil. It is actively carried out. The magnetic resonance coupling type is expected to be applied to various applications.

2A and 2B are equivalent circuit diagrams of the wireless power supply system 2. FIG. As shown in FIG. 2(a), the power transmitting coil _LTX and the power receiving coil _LRX are coupled by a mutual inductance _LM . It is known that such a pair of power transmitting and receiving coils is represented by a T-shaped equivalent circuit as shown in FIG. 2(b). From the equivalent circuit analysis of FIG. 2(b), the maximum transmission efficiency η _max of wireless power is expressed by Equation (1) using the product of the coupling coefficient k and the quality coefficient Q.

FIG. 3 is a diagram showing the maximum efficiency with k ² Q ₁ Q ₂ as a parameter. As can be seen from FIG. 3, the maximum efficiency increases monotonically with kQ, so either the coupling factor k or the quality factor Q is used as a performance indicator of the resonator. It can be understood that the magnetic resonance method improves efficiency by increasing the quality factor Q value.

A. Kurs, et.al., "Wireless power transfer via strongly coupled magnetic resonances", science, vol.317, no.5834, pp.83-86, July 2007. H. D. Lang et.al., "Convex optimization of wireless power transfer systems with multiple transmitters." IEEE transactions on Antennas and Propagation, vol.62, no.9, pp.4623-4636, Sept. 2014 Y. Narusue et.al., "Distributed reactance compensation for printed spiral coils in wireless power transfer," Wireless Power Transfer Conference (WPTC) IEEE, pp.1-4 May 2017.

Conventionally, the design of a resonator used in a real environment relies on experience and requires optimization by cut-and-try. In addition to the fact that the transmission efficiency depends on countless parameters such as the shape, size, number of turns, and pitch of the resonator, there are metal pieces and electronic parts of the power receiving device around the resonator, and loss in the surrounding materials is high. for it arises. Therefore, when designing a resonator, sufficient attention is paid to these operating environments and the parameters are adjusted, resulting in a problem of high design costs.

The present invention has been made in such a situation, and one of the exemplary purposes of certain aspects thereof is to provide a technique for reducing trial and error design effort when designing an antenna coil.

One aspect of the present invention relates to a method of designing an antenna coil. The antenna coil design method includes the step of modeling the surrounding environment including the paired antenna coils, dividing the space in which the antenna to be designed should be placed into a plurality of meshes, and determining the optimality of each mesh in the modeled surrounding environment. and obtaining the shape of the antenna coil to be designed from the current distributions of a plurality of meshes.

Another aspect of the present invention is a method of designing an antenna coil. The antenna coil design method includes the step of modeling the surrounding environment including the paired antenna coils, dividing the space in which the antenna to be designed should be placed into a plurality of meshes, and determining the optimality of each mesh in the modeled surrounding environment. obtaining contours of the distribution of the magnetic dipole moments of the plurality of meshes; and obtaining the shape of the antenna coil based on the contours.

Any combination of the above constituent elements, and any conversion of the expressions of the present invention into devices, methods, systems, recording media, computer programs, etc. are also effective as embodiments of the present invention.

According to the present invention, antenna design can be facilitated.
can provide

1 is a block diagram of a magnetic resonance coupling type wireless power feeding system; FIG. 2A and 2B are equivalent circuit diagrams of the wireless power supply system. FIG. 4 is a diagram showing the maximum efficiency with k ² Q ₁ Q ₂ as a parameter; It is a flow chart of an automatic design method of an antenna coil. FIG. 4 is a diagram for explaining subdivided conductor meshes; 1 is a diagram showing a model of a wireless power supply system to be designed; FIG. It is a figure explaining the influence on Z matrix by sharing a conductor. It is a figure which shows an example of derived|led-out electric current distribution. FIG. 4 is a diagram for explaining a magnetic dipole moment in a minute region; FIG. 9 is a diagram showing an example of the distribution of magnetic dipole moments derived from the current distribution of FIG. 8; 11(a) and 11(b) are diagrams showing an example of the shape of the antenna coil obtained from the magnetic dipole moment distribution of FIG. 1 is an equivalent circuit diagram of a wireless power supply system including multiple transmitting resonators; FIG. 1 is an equivalent circuit diagram of a transmission circuit; FIG. FIG. 3 is an equivalent circuit diagram for explaining dispersion reactance compensation; FIG. 4 is a diagram showing uniformity of current distribution by distributed reactance compensation;

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. Moreover, the embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

1. Overview As shown in FIG. 1 , the wireless power feeding system 2 forms a resonator including a power transmitting device 10 and a power receiving device 20 . In this embodiment, a method for automatically designing an antenna coil (hereinafter also simply referred to as a coil) that forms this resonator will be described. It is assumed that the coil L1 to be automatically designed is one of the power transmitting coil _LTX and the power receiving coil _LRX , and information such as the shape of the other (the paired antenna coil L2) is known.

FIG. 4 is a flow chart of an automatic antenna coil design method. This design method is embodied by a software program, which is loaded into the computer's memory and causes the computer (specifically, the CPU) to execute each process shown in the flowchart.

First, the surrounding environment including the paired coil L2 is modeled (S100). The surrounding environment includes, in addition to the antenna coil L2, various metal and dielectric parts existing around the antenna coil L2 and the coil L1 to be designed. For example, the antenna coils L1, L2 are rarely exposed to space and are usually covered with a dielectric cover, in which case the surrounding environment includes this cover.

Subsequently, the space in which the coil L1 to be designed should be arranged is divided into a plurality of meshes, and the optimum current amount for each mesh in the modeled surrounding environment is calculated (S102). The space may be a two-dimensional plane or a three-dimensional space.

Subsequently, the shape of the coil L1 to be designed is acquired from the current distributions of a plurality of meshes (S104).

The above is the outline of the design method of the antenna coil according to the embodiment. This design method will be described in more detail below.

2. Modeling the Surrounding Environment and Introducing a Conductor Mesh When automatically designing an antenna coil, it is important to consider the physical location of the antenna coil, the three-dimensional shape and material of the material around it, and the paired antenna coils. Given the shape of , we derive the current distribution that maximizes the efficiency at the physical location where the antenna coil is installed. Here, the paired resonator means a power receiving coil (power transmitting coil) if the object of design is a power transmitting coil (power receiving coil).

In the present embodiment, efficiency is defined by power efficiency, but analysis is based on losses in inter-coil coupling and surrounding materials without considering losses in the RF inverter and rectifier circuit.

FIG. 5 is a diagram illustrating a subdivided conductor mesh. The antenna coil L1 to be designed is provided at a position facing the paired antenna coil L2. Here, the paired antenna coil L1 is simply shown as a loop coil with one turn. A space 30 to incorporate the antenna coil L1 to be designed is divided into a plurality of meshes. In this example, the space 30 is a plane with a negligible thickness, and it is assumed that there is no current component in the direction perpendicular to the coil surface of the antenna in the drawing. When deriving the current distribution that maximizes the efficiency, a conductor mesh 32 that is so finely divided that it can be approximated to the conductor surface is assumed on this plane 30 . The size of the conductor mesh 32 may be determined in consideration of the amount of calculation, the required calculation accuracy, etc., and is arranged in a matrix of 100×100, 50×50, and 10×10, for example. Note that the mesh is not limited to a square, and may be set to a rectangle depending on the shape of the area where the antenna coil is set. Therefore, a matrix-like conductor mesh of 50×100 or the like can also be adopted.

3. Derivation of Current Distribution In deriving the current distribution, a circular current I _i flowing in each loop of the conductor mesh 32 is considered. Then, by calculating the value of each circular current I _i that maximizes the efficiency, the current distribution that maximizes the efficiency can be obtained.

FIG. 6 is a diagram showing a model of a wireless power supply system to be designed. If the number of loops is N, N circular currents I ₁ to I _N can be regarded as N loop coils. At this time, including the paired resonators, it can be considered as a network of N+1 ports. Therefore, electromagnetic field simulation, equivalent circuit analysis, or the like is used to calculate the Z-matrix of the N+1 port, and using this, the optimum current distribution is calculated.

V=Z・I
V={ _v1 , _v2 ,... _vN+1 }
I={I ₁ , I ₂ , . . . I _N+1 }

Here, when an interaction occurs between the electromagnetic field generated by the loop current and the surrounding matter, it can be observed as a change in impedance in the conductor mesh, that is, a change in the Z matrix.

The current distribution of N loop coils that maximizes the efficiency of independent N antenna coils on the transmitting side and one paired antenna coil on the receiving side is It can be treated as an efficiency maximization problem, and its solution is known (Non-Patent Document 2). Since the real component matrix R (R=Re[Z]) of the Z matrix is positive semidefinite, the derivation of the current that maximizes the efficiency is reduced to a convex optimization problem.

ここで、ｒ_ｉｊは隣り合うループｉおよびループｊが共有する導体部分の抵抗成分である。導体メッシュおよびペアとなるアンテナコイルと周辺環境は、内部に電源を含まない受動回路網とみなせるため、任意の電流ベクトルＩにより生じる消費電力は常に非負である。したがって、行列Ｒは任意の実ベクトルＩに対して式（３）を満たす。

As for the conductor mesh in the present embodiment, if the matrix R is a positive semidefinite value, the current distribution maximizing the efficiency can be derived as in the case of the MISO system. The difference between a conductor mesh and a MISO system is that the former shares conductors between adjacent loops while the latter does not. FIG. 7 is a diagram explaining the influence on the Z matrix by sharing a conductor. The impedance z contained in both the loop i and the adjacent loop j is incorporated into Z as -z because the directions of the currents flowing through the shared sides are opposite. As a result, the conductor mesh matrix R is represented by the following equation.

Here, r _ij is the resistance component of the conductor portion shared by adjacent loops i and j. The power consumption caused by any current vector I is always non-negative because the conductor mesh and paired antenna coils and surrounding environment can be regarded as a passive network that does not contain a power supply inside. Therefore, matrix R satisfies equation (3) for any real vector I.

Since equation (4) holds for any real vector I, the matrix R is positive semidefinite. Thus, the efficiency maximizing loop coil current distribution in the conductor mesh can be solved similarly to the efficiency maximization problem in the MISO system.

4. Example of current distribution derivation As an initial study, assuming a 100x100 conductor mesh, the current Derive the distribution. Here, constant mutual inductance means that the magnetic field distribution generated by the power receiving resonator is uniform.

FIG. 8 is a diagram showing an example of the derived current distribution. Here, a positive (negative) value for the horizontal direction indicates the right (left) direction, and a positive (negative) value for the vertical direction indicates the upward (downward) direction.

5. Derivation of Shape of Antenna Coil by Magnetic Dipole Moment Derivation of the shape of an antenna coil that reproduces the current distribution as shown in FIG. 8 will be described. Since the derived current distribution of each current loop takes discrete values between each loop, it is difficult to directly reproduce the given current distribution by one coil. Therefore, focusing on the fact that the basic principle of the magnetic resonance coupling type is through the magnetic field generated by the current, as with the electromagnetic induction type, the resonator is designed so as to reproduce the magnetic field generated by each loop.

The magnetic field at position r can be expressed using a magnetic dipole moment. The magnetic dipole moment _m is a vector d is defined as equation (4).

The magnetic field B(r) is represented by Equation (5) using the magnetic dipole moment.

In practice, no singular magnetic poles have been found and the magnetic dipole moment m is defined in equation (6) by the current density J _e (r) at position r and is equivalent to equation (4) is.

Here, r' is the position vector from the origin to the area where the current exists, and V is the area where the current is distributed. From the above, the magnetic dipole moment generated by each loop of the conductor mesh can be obtained and reproduced to generate the magnetic field due to the current distribution. The magnetic dipole moment of the region surrounded by the current loop was defined by Equation (6). Consider the dipole moment.

FIG. 9 is a diagram explaining the magnetic dipole moment of a minute region. Suppose that the surface surrounding the closed loop C through which the conductive current I flows is divided into infinitely small areas of area _ΔSi , and the same current I is virtually passed through all the small loops. Each microloop can be replaced by a magnetic dipole with moment m _i =μ ₀ IΔS _i .

Adjacent currents in the micro loops cancel each other out, leaving only the current flowing in the closed loop C as a whole, and the sum of the magnetic dipole moments possessed by each micro loop matches the original magnetic dipole moment in the loop C.

In other words, loops with the same magnitude of magnetic dipole moment can be reproduced collectively by passing an appropriate current through one loop surrounding them. and the magnitude of the magnetic dipole moment of each loop, Equation (7) can be obtained.

Here, _Si is the area of the region enclosed by the loops, _mi is the magnitude of the magnetic dipole moment produced by the loops in the enclosed region, and _µ0 is the magnetic permeability of vacuum.

FIG. 10 is a diagram showing an example of distribution of magnetic dipole moments derived from the current distribution of FIG.

6. Derivation of Shape of Antenna Coil In this embodiment, contours of the distribution of magnetic dipole moments are used to present the shape of the resonator. Contour lines are drawn every |m _max |/n _{number of turns} . m _max is the maximum value of the magnetic dipole moment.

11(a) and 11(b) are diagrams showing an example of the shape of the antenna coil obtained from the magnetic dipole moment distribution of FIG. Here, for the current distribution of a 100×100 conductor mesh, contours of the magnetic dipole moment are used to determine the approximate shape of the antenna coil, and the number of turns of the coil is set to 5. As shown in FIG. 10(a), the shape of the antenna coil may be specified along the contour lines. can be designed as a single conductor, as shown in FIG. 10(b).

7. Verification of Transmission Efficiency The shape of the antenna coil derived by this design method is compared with the transmission efficiency of the coil shape, which is generally considered to be highly efficient. Here, the transmission efficiency is compared by the kQ product.

ここで、ｉとｊは辺を共有するループである。受電側のコイルに生じる電圧は、共振器の共振角周波数ωを用いて式（９）となるから、Ｍ_{ｔｏｔａｌ}＝ＭΣ_ｉＳ_ｉと定義できる。

A kQ product is obtained from the equivalent circuits of the power transmitting device 10 and the power receiving device 20, and improvement in efficiency is confirmed by the kQ product. FIGS. 12A and 12B are equivalent circuit diagrams of the wireless power feeding system 2 including a plurality of transmitting resonators. When obtaining the kQ product, as shown in FIG. 12(b), a large number of resonators on the transmitting side are combined into one resonator. If the current ratio in each minute loop is defined as S _i =I _i /I _max , the combined resistance component r _total is given by equation (8) based on the loss component caused by the resonator array: expressed.

where i and j are edge-sharing loops. The voltage generated in the coil on the power receiving side can be defined as M _total =MΣ _{i Si} since the resonance angular frequency ω of the resonator is given by Equation (9).

As a result, the integrated kQ product of the power transmitting side resonator and the power receiving side resonator is given by Equation (10).

In order to confirm the usefulness of this method, we compared the antenna coil proposed by this method with the antenna coil in which the windings are concentrated on the outer side, which is generally considered to be highly efficient. When the number of turns is fixed to 5 and the number of conductor meshes is changed to 10x10, 50x50, and 100x100, the ratio of kQ products is 1.24, 1.93, and 3.30, respectively. , the kQ product of the resonator according to this design method is higher. Also, it can be seen that as the number of meshes increases, the amount of improvement in the kQ product increases.

Also, when the number of meshes is fixed at 100x100 and the number of turns is changed to 3, 5, and 7, the kQ products of the resonator according to this design method are 5.18, 3.30, and 2.51, respectively. increased, and an improvement in efficiency was confirmed.

8. Distributed Reactance Compensation The physical geometry of an antenna is limited by frequency. This recognition applies not only to radiation antennas but also to resonators used in magnetic resonance coupling type wireless power transmission. When the operating frequency is high and the shape of the resonator is large, the current distribution becomes uneven, and sometimes the direction of the current inside the resonator is reversed. At that time, the magnetic field is canceled in the resonator, which directly leads to a decrease in the Q value, which is a performance index of the resonator.

Non-uniformity of current distribution is one of the reasons why resonator design parameters are still adjusted on a trial-and-error basis. This design method is also based on the premise that the current flowing through one conductor (antenna coil) is uniform. Therefore, the applicable resonator shape may be limited to a range that can be regarded as electrically compact. If the non-uniformity of the current distribution can be improved, the scope of application of this design method will be greatly expanded.

The non-uniformity of the current distribution is caused by the accumulation of electric charge in parasitic capacitors existing between lines when the conducting wire, which is the antenna coil, is used as a kind of transmission line. 13(a) and 13(b) are equivalent circuit diagrams of lossy and lossless transmission circuits. Let L be the inductance per unit length, C be the capacitance per unit length, and R and G be the loss components associated with L and C, respectively. If R and G can be regarded as sufficiently small, the line becomes a lossless line as shown in FIG. 13(b).

The present inventors have proposed Distributed Reactance Compensation (DRC) (Non-Patent Document 3). This distributed reactance compensation was originally proposed as a technology to weaken the magnetic field strength around the antenna coil and reduce dielectric loss by inserting a reactance compensation capacitor not only in the input port but also in the antenna coil.

Unlike conventional concentrated reactance compensation (CRC), distributed reactance compensation inserts a large number of capacitances in the antenna coil to achieve a resonant state within the coil and reduce the voltage difference between lines. and the charge stored in the parasitic capacitor is reduced.

The present inventors have discovered a phenomenon that not only the dielectric loss is reduced but also the current distribution of the antenna coil is made uniform by the distributed reactance compensation. This phenomenon should not be regarded as a known technique.

FIG. 14 is an equivalent circuit diagram illustrating dispersion reactance compensation. The antenna coil is divided into a plurality of elements with compensating capacitors inserted between them.

FIGS. 15(a) to 15(d) are diagrams showing simulation results of current distribution by distributed reactance compensation. The current distribution of a loop coil with a diameter of 5 m at an operating frequency of 6.78 MHz was calculated by electromagnetic field simulation. The wire diameter of the loop coil was 1 mm, the material was copper, and FEKO manufactured by Altair inc. was used as the simulator.

FIG. 15(a) shows the case without compensation. Distributed reactance compensation is not performed, and the reactance compensation capacitor is connected to the input port. The current distribution is normalized by the maximum value within the resonator. The current intensity is the lowest at the input port portion, remaining at about 30% of the current intensity compared to the portion farthest from the port. The results show that at the operating frequency of 6.78 MHz, the current distribution can be greatly distorted even for an antenna with one turn, and the distortion of the current distribution further increases with increasing number of turns.

FIGS. 15(b) to (d) show simulation results when dispersion reactance compensation is performed. The number N of capacitors used for dispersion reactance compensation is 2, 4, and 8. When the current distribution is uniform, the current in each capacitor and the current through the input port are equal in magnitude and direction. Based on this condition, the capacitance that makes the current distribution uniform is considered.

For the derivation of the capacitance, an electromagnetic field simulation is performed with the points where the capacitors are connected as ports, and S-parameters derived as a circuit network of N+1 ports are used. Using the Z parameter obtained by converting the S parameter, the condition that the currents of the ports are equal to I can be described by −Z _c I=Z′(1, 1, 1, . . . , 1) ^T I . Here, Z′ is an N×(N+1) matrix obtained by deleting rows corresponding to input ports from the impedance matrix Z, and _Zc is an Nth-order row vector consisting of impedances of connected capacitors. The capacitance to be connected is found by solving equation (11).
_Zc = -Z'(1, 1, 1, ..., 1) ^T (11)

Capacitors were placed at equal intervals in a loop coil with a diameter of 5 m, and the capacitance was calculated by equation (11). It was 98.1 pF and 179.4 pF when N=8.

In FIGS. 15(b) to 15(d), in order to show the current distribution in more detail, it should be noted that the correspondence between the shading and the current value differs depending on each figure. It can be confirmed that the current distribution is equal at the input port and the capacitor insertion portion, and that the current distribution becomes more uniform as the number of capacitors used for distributed reactance compensation increases. When N=8, the difference in current intensity within the resonator is suppressed to 1% or less.

The reason why the current distribution becomes uniform by the distributed reactance compensation can be considered from the transmission line theory. When the conducting wire in the resonator is regarded as a kind of transmission line, the non-uniform current distribution is caused by the accumulation of electric charge in the parasitic capacitor existing between the lines. Distributed reactance compensation reduces the potential difference between lines by arranging a large number of capacitances in the resonator.

By performing distributed reactance compensation in this way, the current distribution of the antenna coil can be made uniform. Therefore, it is preferable to incorporate dispersion reactance compensation into the software program using this design method when designing an antenna used in a frequency band of several MHz or more.

The design method described above determines the shape of the antenna coil. Additional processing for dispersion compensation is then performed on the antenna coil. The number N of capacitors to be inserted may be specified manually, or the non-uniformity of the current without compensation is calculated as shown in FIG. A number N may be determined.

If the shape of the antenna coil is known, the S parameter (Z parameter) can be calculated when it is regarded as a transmission line. Once N is determined, the capacitance value of the capacitor to be inserted can be calculated by solving equation (11) using the Z parameter.

Although the present invention has been described using specific terms based on the embodiments, the embodiments merely show the principles and applications of the present invention, and the embodiments are defined in the scope of claims. Many modifications and changes in arrangement are permitted without departing from the spirit of the present invention.

2 wireless power supply system 10 power transmission device 20 power reception device L _TX power transmission coil C _TX resonance capacitor L _RX power reception coil C _RX resonance capacitor

Claims (8)

A method for designing an antenna coil using a computer ,
said computer modeling an ambient environment including paired antenna coils;
a step in which the computer divides the space in which the antenna to be designed should be placed into a plurality of meshes, and calculates the amount of current that maximizes the efficiency of each mesh in the modeled ambient environment;
a step in which the computer acquires the shape of the antenna coil to be designed from the current distribution of the plurality of meshes;
A method of designing an antenna coil, comprising: the computer calculating a magnetic dipole moment distribution from the current distribution of the plurality of meshes;
the computer obtaining contours of the distribution of the magnetic dipole moment;
2. The design method according to claim 1, wherein the shape of the antenna coil to be designed corresponds to the contour lines. A method for designing an antenna coil using the computer ,
said computer modeling an ambient environment including paired antenna coils;
a step in which the computer divides the space in which the antenna to be designed should be placed into a plurality of meshes, and calculates a magnetic dipole moment that maximizes the efficiency of each mesh in the modeled ambient environment;
the computer obtaining contours of the distribution of magnetic dipole moments of the plurality of meshes;
the computer acquiring the shape of the antenna coil based on the contour lines;
A method of designing an antenna coil, comprising: 4. The antenna according to any one of claims 1 to 3, wherein the computer further comprises a step of dividing the antenna to be designed into a plurality of elements and inserting capacitors between the divided elements. Coil design method. to the computer,
modeling an ambient environment including paired antenna coils;
a step of dividing the space in which the antenna to be designed should be placed into a plurality of meshes, and calculating the amount of current that maximizes the efficiency of each mesh in the modeled ambient environment;
obtaining the shape of the antenna coil from the current distribution of the plurality of meshes;
program to run the to said computer;
calculating a distribution of magnetic dipole moments from the current distribution of the plurality of meshes;
obtaining contours of the distribution of the magnetic dipole moment;
obtaining a shape of the antenna coil to be designed according to the contour lines;
6. The program according to claim 5, further causing the execution of to the computer,
modeling an ambient environment including paired antenna coils;
dividing the space in which the antenna to be designed should be arranged into a plurality of meshes, and calculating the magnetic dipole moment that maximizes the efficiency of each mesh in the modeled ambient environment;
obtaining contours of the distribution of magnetic dipole moments of the plurality of meshes;
obtaining a shape of the antenna coil to be designed based on the contour lines;
A program characterized by causing the execution of to the computer,
8. The program according to any one of claims 5 to 7, further causing a step of dividing the antenna to be designed into a plurality of elements and inserting capacitors between the divided elements.

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