JP7401766B2 - Antenna design program, antenna design method, and information processing device - Google Patents

Description

The present invention relates to an antenna design program, an antenna design method, and an information processing device.

Patch antennas (also called microstrip antennas) are known as a type of planar antenna mounted on wireless devices. A patch antenna has a dielectric substrate, a conductor pattern called a patch formed on the surface of the dielectric substrate, and a ground conductor plate formed on the back surface of the dielectric substrate. Further, a feed point is provided at a predetermined position of the patch, and for example, the center conductor of the coaxial line passes through the ground conductor plate and the dielectric substrate from the back surface of the patch antenna, and comes into contact with the patch at the feed point.

Note that there has conventionally been a method of designing an antenna that can suppress deterioration of the reflection characteristics of the antenna when it comes close to metal (see, for example, Patent Document 1). Further, as a design method for patch antennas, there are methods using numerical optimization methods such as deep learning (for example, see Non-Patent Document 1).

Japanese Patent Application Publication No. 2016-036135

R. K. Mishra and A. Patnaik, “Neural Network-Based CAD Model for the Design of Square-Patch Antennas”, IEEE transactions on antennas and propagation, December 1998, vol. 46, no. 12, p.1890-1891

However, when designing a patch antenna, there is a problem in that it is difficult to determine the size of the patch and the feeding position in order to match the input impedance, and the design takes time. Design using numerical optimization techniques similarly takes time because it requires the effort of preparing a large number of samples for learning.

In one aspect, an object of the present invention is to provide an antenna design program, an antenna design method, and an information processing device that can shorten the design time of a patch antenna.

In one embodiment, a first frequency at which the reflection coefficient of the patch antenna is minimized is detected based on a first result of an electromagnetic field simulation using design information of the patch antenna, and the first frequency is matched with a specified operating frequency. Based on the comparison result with the detected first frequency, calculate the side length of the patch of the patch antenna that reduces the reflection coefficient at the operating frequency, and calculate the side length of the patch on the Smith chart obtained from the first result. An antenna design program that causes a computer to perform a process of calculating a feeding position of the patch antenna that brings the input impedance at the operating frequency closer to the center point of the Smith chart based on a locus of the input impedance of the patch antenna is provided. be done.

Also, in one embodiment, an antenna design method is provided.
Further, in one embodiment, an information processing device is provided.

In one aspect, the present invention can reduce patch antenna design time.

1 is a diagram illustrating an example of an antenna design method and an information processing device according to a first embodiment; FIG. FIG. 7 is a diagram illustrating an example of adjusting the side length of a patch and the power feeding position. FIG. 3 is a diagram showing an example of the relationship between the imaginary part of input impedance and frequency. FIG. 2 is a block diagram illustrating an example of hardware of an information processing device. FIG. 2 is a block diagram illustrating a functional example of an information processing device. 3 is a flowchart illustrating an example of a procedure of an antenna design method. FIG. 3 is a diagram showing an example of a locus of input impedance in a Smith chart. FIG. 3 is a diagram showing an example of estimating the locus of input impedance in a Smith chart. FIG. 3 is a diagram showing an example of adjustment of patch size and power feeding position.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram illustrating an example of an antenna design method and an information processing apparatus according to the first embodiment.

The information processing device 10 designs a patch antenna 15 as shown in FIG. 1, for example. FIG. 1 shows the top surface of the patch antenna 15 and a cross section taken along the line AA. The patch antenna 15 includes a dielectric substrate 15a, a patch (conductor pattern) 15b formed on the surface of the dielectric substrate 15a, and a ground conductor plate 15c formed on the back surface of the dielectric substrate 15a. Further, a feed point 15d is provided at a predetermined position of the patch 15b, and for example, a center conductor 15da of a coaxial line passes through the ground conductor plate 15c and the dielectric substrate 15a from the back surface of the patch antenna 15, and at the feed point 15d. Patch 15b is contacted. Further, the outer conductor 15db of the coaxial line is brought into contact with the ground conductor plate 15c.

The information processing device 10 includes a storage section 11 and a processing section 12.
The storage unit 11 is a volatile storage device such as a RAM (Random Access Memory), or a nonvolatile storage device such as an HDD (Hard Disk Drive) or flash memory.

The storage unit 11 stores design information 11a and electromagnetic field simulation results 11b.
The design information 11a is expressed by, for example, the side length of the patch 15b of the patch antenna 15 (l _x and ly in FIG. ₁ ), the feeding position (the position of the feeding point 15d, and the distance (f _y ) from the center of the patch 15b). ), etc. The initial value of the design information 11a is calculated, for example, using a calculation formula described below.

The electromagnetic field simulation result 11b is the result of an electromagnetic field simulation performed using the design information 11a. As the electromagnetic field simulation, for example, a simulation using the FDTD (Finite-Difference Time-Domain method) method, the moment method, or the finite element method can be applied. The electromagnetic field simulation result 11b includes |S ₁₁ | and input impedance at each frequency. S ₁₁ is a value called a reflection coefficient, and the smaller |S ₁₁ | indicates better matching.

Note that the information processing device 10 may execute the electromagnetic field simulation, or another information processing device may execute the electromagnetic field simulation, and the information processing device 10 may acquire the result and store it in the storage unit 11. good.

The processing unit 12 is realized by a processor that is hardware such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit). However, the processing unit 12 may include an electronic circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). A processor executes programs stored in memory such as RAM. For example, an antenna design program is executed. Note that a set of multiple processors is sometimes referred to as a "multiprocessor" or simply "processor."

The processing unit 12 performs the following processing (antenna design method).
The processing unit 12 detects a frequency (which can also be called a resonant frequency) f _s at which the reflection coefficient of the patch antenna 15 is the minimum based on the electromagnetic field simulation result 11b (step S1).

Then, the processing unit 12 calculates the side length of the patch 15b of the patch antenna 15 that reduces the reflection coefficient at the operating frequency f _o based on the comparison result between the specified operating frequency f _o and the detected frequency f _s . (Step S2).

The calculated side length of the patch 15b is ly, which is the _length of the side in the y direction, when the feeding point 15d is shifted in the y direction from the center of the patch 15b. Note that the shape of the patch 15b is not limited to a rectangle or a square, but may be circular. In that case, the calculated side length of the patch is the radius of the circle.

When l _y is shortened, the frequency f _s at which the reflection coefficient is minimum becomes higher. Therefore, when f _s > f _o , in order to reduce the reflection coefficient at the operating frequency f _o , it is sufficient to make ly longer than the _length represented by the current design information 11a. On the other hand, when f _s <f _o , in order to reduce the reflection coefficient at the operating frequency f _o , _ly should be made shorter than the length represented by the current design information 11a. For example, the processing unit 12 can calculate the side length of the new patch 15b by multiplying _ly represented by the current design information 11a by _fs / _fo .

Furthermore, the processing unit 12 calculates a feeding position that brings the input impedance at the operating frequency _fo closer to the center point of the Smith chart based on the locus of the input impedance of the patch antenna 15 on the Smith chart (step S3).

The above trajectory is obtained from the electromagnetic field simulation result 11b. As the power feeding position moves away from the center of the patch 15b, the size of the circle that is the locus of the input impedance increases. Therefore, if the circle that is the locus of input impedance includes the center point of the Smith chart, the processing unit 12 moves the power feeding position indicated by the design information 11a closer to the center of the patch 15b, and if the circle does not include the center point, the processing unit 12 moves the power feeding position indicated by the design information 11a closer to the center of the patch 15b. The position is moved away from the center of patch 15b. Such processing is performed because good impedance matching can be obtained by bringing the input impedance at the operating frequency _fo close to the center point of the Smith chart.

Note that the processing unit 12 may output and display the side length and power feeding position of the patch 15b calculated in steps S2 and S3 on a display device (not shown).
Further, the processing unit 12 updates the design information 11a stored in the storage unit 11 using the calculated side length and power feeding position of the patch 15b (step S4).

Note that the above processing order is an example, and the processing order may be changed as appropriate. For example, the process in step S3 may be performed before the process in step S1.
Furthermore, the above steps S1 to S4 may be repeated to design a patch antenna 15 with better characteristics.

FIG. 2 is a diagram showing an example of adjusting the side length of the patch and the power feeding position.
FIG. 2 shows an example of the relationship between the side length of a patch obtained by electromagnetic field simulation and the frequency characteristic of S ₁₁ [dB]. The size of the dielectric substrate 15a is 70×70×3.2 mm ³ , and a power feeding point (not shown) is at the center of the patch 15b. Further, the dielectric substrate 15a has a dielectric constant of 2.17, a dielectric loss tangent of 0.001, and the patch 15b and the ground conductor plate 15c shown in FIG. 1 are perfect conductors with a thickness of 0.

Characteristic 20 shows the frequency characteristic of S ₁₁ when l _y (=l _x )=60 mm, characteristic 21 shows the frequency characteristic of S 11 when l _y (=l _x )=50 mm, and characteristic 22 shows the frequency characteristic of S ₁₁ when l y (=l x )=50 mm. The frequency characteristics of _S11 when _y (=l _x )=40 mm are shown.

The shorter the side length of the patch 15b, the higher the frequency at which S ₁₁ [dB] is minimum. For example, when the _ly of the patch 15b in the current design information 11a is 60 mm, the detected frequency f _s is approximately 1.6 GHz. When the specified operating frequency f _o is 1.9 GHz, the reflection coefficient at the operating frequency f _o can be reduced by reducing ly to _{approximately} 50 mm. On the other hand, when the _ly of the patch 15b in the current design information 11a is 40 mm, the detected frequency f _s is approximately 2.4 GHz. When the specified operating frequency f _o is 1.9 GHz, the reflection coefficient at the operating frequency f _o can be reduced by expanding _ly to approximately 50 mm.

FIG. 2 further shows the relationship between the power supply position obtained by electromagnetic field simulation and the locus of input impedance on the Smith chart 25. The size of the dielectric substrate 15a is 70×70×3.2 mm ³ , and the size of the patch 15b is 47×47 mm ² . Further, the dielectric substrate 15a has a dielectric constant of 2.17, a dielectric loss tangent of 0.001, and the patch 15b and the ground conductor plate 15c shown in FIG. 1 are perfect conductors with a thickness of 0.

The locus 26 is the locus of input impedance when the distance (f _y ) from the center of the patch 15b of the feeding point 15d is 5.0 mm, and the locus 27 is the locus of the input impedance when f _y =8.3 mm. It is. Further, a locus 28 is a locus of input impedance when f _y =15 mm. The locus 27 passes through the center point (reference impedance (hereinafter referred to as 50Ω)) of the Smith chart 25, and is a locus that may provide good impedance matching at the operating frequency _fo .

As shown in FIG. 2, the farther the feeding point 15d is from the center of the patch 15b, the larger the circle that is the locus of the input impedance becomes. For example, in the current design information 11a, when f _y =5.0 mm, the input impedance locus 26 does not include the center point of the Smith chart 25. Therefore, by moving the power feeding point 15d away from the center of the patch 15b, the locus 26 can be brought closer to the locus 27. On the other hand, in the current design information 11a, when f _y =15 mm, the input impedance locus 28 includes the center point of the Smith chart 25. Therefore, by moving the feeding point 15d closer to the center of the patch 15b, the trajectory 28 can be moved closer to the trajectory 27.

By the way, matching of input impedance means adjusting the imaginary part of the input impedance to 0Ω and the real part to 50Ω.
FIG. 3 is a diagram showing an example of the relationship between the imaginary part of input impedance and frequency. The vertical axis represents the imaginary part [Ω] of the input impedance, and the horizontal axis represents the frequency [Hz].

The imaginary part of the input impedance exhibits complex behavior as shown in Figure 3, so if you want a computer to design a patch antenna that matches the impedance at a certain frequency based on these characteristics, you will need to do the following: There is a possibility that it will be processed.

For example, if the imaginary part of the input impedance is desired to be 0Ω at 1.75 GHz, the value of the imaginary part becomes smaller as the frequency is lowered from 1.75 GHz. Therefore, it is possible to design a patch antenna so that the overall characteristics shown in FIG. 3 are shifted to the right. However, as shown in FIG. 3, the value of the imaginary part becomes 0Ω around 2.00 GHz, and the direction in which the shift should be made is the opposite. Therefore, when designing a patch antenna that can obtain impedance matching based on the frequency characteristics as shown in FIG. 3, it may take a long time.

Further, as described above, even in design using a numerical optimization method, it takes time to prepare a large number of samples for learning, so the design similarly takes time.
In contrast to these design methods, in the antenna design method of the first embodiment, the patch side length is calculated based on the comparison result between the frequency f _s with the minimum reflection coefficient and the operating frequency f _o as described above, The power feeding position is calculated based on the input impedance locus on the Smith chart. This facilitates impedance matching and reduces design time.

(Second embodiment)
Next, a second embodiment will be described.
FIG. 4 is a block diagram showing an example of hardware of the information processing device.

The information processing device 30 includes a CPU 31 , a RAM 32 , an HDD 33 , an image signal processing section 34 , an input signal processing section 35 , a medium reader 36 , and a communication interface 37 . The above units are connected to a bus.

The CPU 31 is a processor that includes an arithmetic circuit that executes program instructions. The CPU 31 loads at least part of the program and data stored in the HDD 33 into the RAM 32, and executes the program. Note that the CPU 31 may include multiple processor cores, the information processing device 30 may include multiple processors, and the processing described below may be executed in parallel using multiple processors or processor cores. . Furthermore, a set of multiple processors (multiprocessor) may be referred to as a "processor."

The RAM 32 is a volatile semiconductor memory that temporarily stores programs executed by the CPU 31 and data used for calculations by the CPU 31. Note that the information processing device 30 may include a type of memory other than RAM, or may include a plurality of memories.

The HDD 33 is a nonvolatile storage device that stores software programs such as an OS (Operating System), middleware, and application software, and data. The program includes, for example, an antenna design program that causes the information processing device 30 to execute patch antenna design processing. Note that the information processing device 30 may include other types of storage devices such as flash memory and SSD (Solid State Drive), or may include a plurality of nonvolatile storage devices.

The image signal processing unit 34 outputs an image to a display 34a connected to the information processing device 30 according to instructions from the CPU 31. As the display 34a, a CRT (cathode ray tube) display, a liquid crystal display (LCD), a plasma display (PDP), an organic electro-luminescence (OEL) display, etc. can be used. .

The input signal processing unit 35 acquires an input signal from an input device 35a connected to the information processing device 30 and outputs it to the CPU 31. As the input device 35a, a pointing device such as a mouse, a touch panel, a touch pad, or a trackball, a keyboard, a remote controller, a button switch, or the like can be used. Further, a plurality of types of input devices may be connected to the information processing apparatus 30.

The medium reader 36 is a reading device that reads programs and data recorded on the recording medium 36a. As the recording medium 36a, for example, a magnetic disk, an optical disk, a magneto-optical disk (MO), a semiconductor memory, etc. can be used. Magnetic disks include flexible disks (FDs) and HDDs. Optical discs include CDs (Compact Discs) and DVDs (Digital Versatile Discs).

For example, the media reader 36 copies programs and data read from the recording medium 36a to other recording media such as the RAM 32 and the HDD 33. The read program is executed by the CPU 31, for example. Note that the recording medium 36a may be a portable recording medium, and may be used for distributing programs and data. Further, the recording medium 36a and the HDD 33 are sometimes referred to as computer-readable recording media.

The communication interface 37 is an interface that is connected to the network 37a and communicates with other information processing devices via the network 37a. The communication interface 37 may be a wired communication interface connected to a communication device such as a switch via a cable, or a wireless communication interface connected to a base station via a wireless link.

The information processing device 10 shown in FIG. 1 can also be realized with the same hardware configuration as above.
Next, the functions and processing procedures of the information processing device 30 will be explained.
FIG. 5 is a block diagram showing a functional example of the information processing device.

The information processing device 30 includes a design condition specification reception section 41, an initial design information setting section 42, a design information storage section 43, an electromagnetic field simulation execution section 44, a simulation result storage section 45, an investigation section 46, a patch size calculation section 47, and a power supply section. It has a position calculation section 48 and an update section 49.

The design information storage section 43 and the simulation result storage section 45 can be implemented using storage areas secured in the RAM 32 or the HDD 33, for example. The design condition specification reception unit 41, the initial design information setting unit 42, the electromagnetic field simulation execution unit 44, the investigation unit 46, the patch size calculation unit 47, the power supply position calculation unit 48, and the update unit 49 are program modules executed by the CPU 31, for example. It can be implemented using

The design condition specification acceptance unit 41 accepts, for example, a design condition specification made by a user by operating the input device 35a. The specified design conditions include, for example, the operating frequency f _o of the patch antenna and substrate characteristics.

The initial design information setting unit 42 sets initial design information of the patch antenna based on the designated design conditions. The initial design information includes initial values for patch size and power feeding position.
In the patch antenna 15 as shown in FIG. 1, the initial values of the patch size (initial values of l _{x and ly} ) can be calculated as follows, for example, when the patch 15b is square.

First, the initial value of l _x is calculated using the following equation (1).

In equation (1), μ ₀ is the magnetic permeability of vacuum, ε ₀ is the permittivity of vacuum, and ε _r is the relative permittivity of the dielectric substrate 15a. Next, using the calculated initial value of l _x , the effective dielectric constant ε _eff is calculated by the following equation (2).

In formula (2), h is the height (thickness) of the dielectric substrate 15a. Then, using the calculated initial value of l _x and ε _eff , the initial value of l _y is calculated by the following equation (3).

If the _difference between _l Using l _y as l _x , calculations of equations (2) and (3) are repeated.

The initial value of the patch size is obtained by the recursive calculation as described above. However, the calculation method described above is not limited to obtaining the initial value of the patch size; the initial value may be input by the user, or the initial value may be set based on past design results. You may also do so.

The initial value of the power feeding position is not particularly limited, but is set, for example, so that the distance from the center of the patch is 1/4 of the initial value of _ly .
The design information storage section 43 stores the design information set by the initial design information setting section 42 or the design information updated by the updating section 49.

The electromagnetic field simulation execution unit 44 executes an electromagnetic field simulation using the FDTD method, moment method, finite element method, or the like based on design conditions and design information. Note that the processing of the electromagnetic field simulation execution unit 44 may be performed by a device different from the information processing device 30.

The simulation result storage unit 45 stores electromagnetic field simulation results. The electromagnetic field simulation results include reflection coefficients and input impedances at each frequency.

The investigation unit 46 detects the frequency f _s at which the reflection coefficient of the patch antenna is minimum based on the electromagnetic field simulation results. The investigation unit 46 also detects the magnitude relationship between the detected frequency f _s and the operating frequency f _o and determines whether the reflection coefficient (|S ₁₁ |) is smaller than a specified value. Furthermore, the investigation unit 46 estimates the locus (circle) of the input impedance of the patch antenna 15 on the Smith chart, and determines whether the circle includes the center point of the Smith chart (whether the circle is too large or not). conduct.

The patch size calculation unit 47 calculates a patch size (patch side length) that reduces the reflection coefficient at the operating frequency f _o based on the comparison result between the specified operating frequency f _o and the detected frequency f _s .

The power supply position calculation unit 48 calculates a power supply position that brings the input impedance at the operating frequency _fo closer to the center point of the Smith chart, based on the estimated locus of input impedance.

The updating unit 49 updates the design information using the calculated patch size and power feeding position.
Note that the information processing device 30 may include a display unit that displays, for example, the calculated patch size, power feeding position, or updated design information on the display 34a.

FIG. 6 is a flowchart illustrating an example of the procedure of the antenna design method.
When the design condition specification receiving unit 41 receives the design condition specification (step S10), the initial design information setting unit 42 sets initial design information of the patch antenna based on the specified design condition (step S11). . As a result, the initial design information of the patch antenna is stored in the design information storage section 43.

Then, the electromagnetic field simulation execution unit 44 executes an electromagnetic field simulation based on the design conditions and design information (step S12). The electromagnetic field simulation results are stored in the simulation result storage section 45.

The investigation unit 46 investigates (detects) the frequency f _s at which |S ₁₁ | becomes the minimum based on the electromagnetic field simulation results (step S13). Then, the investigating unit 46 determines whether f _s ≒ f _o (the difference between the frequency f _s and the operating frequency f _o is smaller than a predetermined threshold) and whether |S ₁₁ | at the frequency f _s is smaller than the specified value. (Step S14). The specified value is appropriately set, for example, −10 dB, −15 dB, etc., depending on the target performance.

If it is determined that f _s ≈f _o and |S ₁₁ | at frequency f _s is smaller than the specified value, the design of the patch antenna is ended without updating the current design information.
If it is determined that f _s ≒ f _o and |S ₁₁ | at frequency f _s is smaller than the specified value, the investigation unit 46 determines whether f _s ≒ f _o . (Step S15).

If it is determined that f _{s ≈fo} , the investigation unit 46 determines whether f _s > _fo (step S16).
If it is determined that f _s > f _o , the patch size calculation unit 47 enlarges the patch (makes l _x and l _y longer) than that represented by the current design information (step S17). .

If it is determined that f _s > f _o , the patch size calculation unit 47 reduces the patch size (shortens l _x , l _y ) than that represented by the current design information (step S18). .

Furthermore, in the processing of steps S17 and S18, the update unit 49 updates the current design information using the obtained new patch size. In addition, in the processing of steps S17 and S18, the patch size calculation unit 47 multiplies l _x , ly expressed in the current design information by f _s / _{f o to} obtain the side length of the new patch 15b. may be calculated.

In the process of step S15, if it is determined that f _s ≈f _o , the investigation unit 46 estimates the locus (circle) of the input impedance on the Smith chart (step S19).
Then, the investigation unit 46 determines whether the circle is too large (including the center point of the Smith chart) (step S20).

FIG. 7 is a diagram showing an example of a locus of input impedance in a Smith chart.
In FIG. 7, the input impedance point P0 at the operating frequency _fo is plotted on the Smith chart 50. However, just by plotting the point P0, it is not clear whether the input impedance locus is the locus 51a or 51b.

The locus 51a includes the center point of the Smith chart 50, so if the input impedance shows such a locus 51a, the power feeding position should be adjusted closer to the center of the patch to make the circle smaller as described above. become. On the other hand, since the locus 51b does not include the center point of the Smith chart 50, if the input impedance shows such a locus 51b, the power supply position should be moved away from the center of the patch to make the circle larger as described above. Adjustments will be made to move it further away. In this way, the adjustment method changes depending on whether the locus of the input impedance is either the locus 51a or 51b.

Therefore, the investigation unit 46 estimates the trajectory (circle) as follows, for example, and determines whether the circle is too large.
FIG. 8 is a diagram showing an example of estimating the locus of input impedance in a Smith chart.

The investigation unit 46 uses the point P0 as the origin, the y-axis passing through the center point of the Smith chart 50 (the value of the y-coordinate of the center point is positive), and the x-y coordinates based on the x-axis passing through the point P0 and perpendicular to the y-axis. Set up the system. Then, when each point on the Smith chart 50 is represented by xy coordinates through coordinate transformation, the investigating unit 46 determines whether the value of the y coordinate of the input impedance point at a frequency different from the operating frequency f _o is positive. Depending on the negative value, it is determined whether the locus includes the center point of the Smith chart 50.

For example, the investigating unit 46 determines the value of the y-coordinate of the input impedance point P1 at a frequency lower than the operating frequency f _o (for example, a frequency indicating |S ₁₁ | that is 1 dB higher than |S ₁₁ | at the operating frequency f _o ). Determine whether is positive or negative. If the value of the y-coordinate of point P1 is positive, the investigation unit 46 estimates that the input impedance locus is a locus 51a that includes the center point, and determines that the circle is too large. If the value of the y-coordinate of point P1 is negative, the investigation unit 46 estimates that the input impedance locus is a locus 51b that does not include the center point, and determines that the circle is too small.

Returning to the explanation of FIG. 6.
In the process of step S20, if it is determined that the circle is too large, the power feeding position calculation unit 48 moves the power feeding position inward (closer to the center of the patch) (step S21).

If it is not determined that the circle is too large (if the circle is too small), the power feeding position calculation unit 48 moves the power feeding position outward (away from the center of the patch) (step S22).
Furthermore, in the processing of steps S21 and S22, the update unit 49 updates the current design information using the obtained new power feeding position.

The power feeding position obtained in step S21 or step S22 is determined as follows, for example.
When the process of step S21 or step S22 is performed on the initial value of the power feeding position represented by the distance of the power feeding point from the center of the patch, the power feeding position calculation unit 48 changes the initial value by 10%. That is, when performing the process of step S21, the power supply position calculation unit 48 calculates the initial value x 0.9 as the new power supply position, and when performing the process of step S22, the power supply position calculation unit 48 calculates the initial value x 1.1 as the new power supply position. Calculate as a position. In the second and subsequent adjustments of the power supply position, for example, the power supply position calculation unit 48 adjusts the current power supply position according to how much the size of the circle that is the locus of input impedance has changed due to the previous change in the power supply position. Change the value by which the position is multiplied. For example, if the change in the size of the circle is too large, the degree to which the power feeding position is changed is reduced.

After the processing in steps S21 and 22, the electromagnetic field simulation execution unit 44 determines whether the number of electromagnetic field simulations (denoted as "Sim number" in FIG. 6) is less than the specified number of times (step S23 ).

The prescribed number of times is appropriately set, for example, 10 times, 20 times, etc. If it is determined that the number of electromagnetic field simulations is less than the specified number of times, the process from step S12 is repeated, and if the number of electromagnetic field simulations reaches the specified number of times, the design of the patch antenna is completed.

Note that the above processing order is not particularly limited, and the processing order may be changed as appropriate.
FIG. 9 is a diagram illustrating an example of adjusting patch size and power feeding position.

The design conditions used for the electromagnetic field simulation are as follows. The operating frequency f _o is 2.45 GHz, the patch and ground conductor plate are perfect conductors with zero thickness, the size of the ground conductor plate is 60 x 60 mm ² , the size of the dielectric substrate is 60 x 60 x 3.2 mm ³ , dielectric The dielectric constant of the substrate is 3.0, and the substrate loss of the dielectric substrate is 0.0.

The patch side lengths (l _x and l _y ) of the first model are values calculated using equations (1) to (3) above based on the above design conditions. Further, the power feeding position (distance from the center of the patch) of the first model is 1/4 of the patch side length.

As a result of electromagnetic field simulation for the first model, the frequency f _s at which S ₁₁ is minimum is 2.35 GHz, and S ₁₁ is −16.083 dB. Further, S ₁₁ at the operating frequency f _o of 2.45 GHz was −4.694 dB.

In the above case, since f _s <f _o , the process of reducing the patch in step S18 in FIG. 6 is performed. In the example of FIG. 9, 32.9 mm, which is the value obtained by multiplying the initial value of the patch side length of 34.2 mm by f _s / _fo , is obtained as the patch side length of the second model.

Furthermore, since it is determined that the circle that is the locus of the input impedance on the Smith chart is too large, the process of moving the power feeding position inward in step S21 in FIG. 6 is performed. In the example of FIG. 9, a value of 8.23 mm, which is a shortening of the initial value of the power feeding position of 8.55 mm, is obtained as the power feeding position of the second model.

As a result of electromagnetic field simulation for the second model, the frequency f _s at which S ₁₁ is minimum was 2.45 GHz, which coincided with the operating frequency f _o . S ₁₁ at f _s =f _o was −17.238 dB.

In the above case, f _s = f _o , so if S ₁₁ is smaller than the specified value (for example, if the specified value is −15 dB), the design of the patch antenna is completed by the determination process in step S14. . However, here, it is assumed that S ₁₁ <the specified value. In that case, in the above example, since f _s =f _o , the patch side length is not adjusted, but since it is determined that the circle is too large, processing is performed to move the power feeding position inward. In the example of FIG. 9, the power supply position of the third model is 3.29 mm, which is a value obtained by shortening the power supply position of the second model, which is 8.23 mm.

As a result of electromagnetic field simulation for the third model, the frequency f _s at which S ₁₁ is minimum was 2.4 GHz, and S ₁₁ was −4.621 dB. Furthermore, S ₁₁ at the operating frequency f _o of 2.45 GHz was −2.542 dB.

Assuming that 2.4 GHz≈2.45 GHz, the patch side length is not adjusted, but since it is determined that the circle is too small, processing is performed to move the power feeding position inward. In the example of FIG. 9, the power supply position of the fourth model is 7.48 mm, which is the length of the power supply position of the third model, which is 3.29 mm.

As a result of electromagnetic field simulation for the fourth model, the frequency f _s at which S ₁₁ is minimum was 2.44 GHz, and S ₁₁ was −24.725 dB. Further, S ₁₁ at the operating frequency f _o of 2.45 GHz was −20.042 dB.

In the above case, 2.44≒2.45, and if _S11 is smaller than the specified value (for example, if the specified value is -20 dB), the design of the patch antenna is terminated by the determination process in step S14. Ru. However, here, it is assumed that 2.44≈2.45 is not satisfied.

In this case, since f _s <f _o , the process of reducing the patch in step S18 in FIG. 6 is performed. In the example of FIG. 9, the patch side length of the fifth model is 32.8 mm, which is the value obtained by multiplying the patch side length of the fourth model, 32.9 mm, by f _s / _fo .

Furthermore, since it is determined that the circle that is the locus of the input impedance on the Smith chart is too large, processing is performed to move the power feeding position inward. In the example of FIG. 9, a value obtained by shortening 7.48 mm, which is the power feeding position of the fourth model, to 7.45 mm is obtained as the power feeding position of the fifth model.

As a result of electromagnetic field simulation for the fifth model, the frequency f _s at which S ₁₁ is minimum was 2.445 GHz, and S ₁₁ was −24.663 dB. Furthermore, S ₁₁ at the operating frequency f _o of 2.45 GHz was −24.132 dB.

FIG. 9 shows the patch side length, feeding position, and frequency characteristics of the reflection coefficient of the fifth model patch antenna.
As described above, according to the antenna design method of the second embodiment, the patch side length is calculated based on the comparison result between the frequency f _s with the minimum reflection coefficient and the operating frequency f _o , and the input impedance of the Smith chart is The power feeding position is calculated based on the trajectory of This facilitates impedance matching and reduces design time, which is the same effect as the antenna design method of the first embodiment.

Furthermore, by repeating the processes from step S12 to step S23 as described above, better impedance matching can be obtained at the operating frequency, and a patch antenna with better performance can be designed.

Note that, as described above, the above processing contents can be realized by causing the information processing device 30 to execute a program.
The program can be recorded on a computer-readable recording medium (for example, the recording medium 36a). As the recording medium, for example, a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc. can be used. Magnetic disks include FDs and HDDs. Optical discs include CDs, CD-Rs (recordables)/RWs (rewritables), DVDs, and DVD-Rs/RWs. A program may be recorded on a portable recording medium and distributed. In that case, the program may be copied from the portable recording medium to another recording medium (for example, HDD 33) and executed.

Although one aspect of the antenna design program, antenna design method, and information processing apparatus of the present invention has been described above based on the embodiments, these are merely examples, and the present invention is not limited to the above description.

10 Information processing device 11 Storage unit 11a Design information 11b Electromagnetic field simulation result 12 Processing unit 15 Patch antenna 15a Dielectric substrate 15b Patch 15c Ground conductor plate 15d Feeding point 15da Center conductor 15db Outer conductor

Claims (7)

detecting a first frequency at which the reflection coefficient of the patch antenna is minimized based on a first result of an electromagnetic field simulation using design information of the patch antenna;
Calculating a side length of a patch of the patch antenna that reduces the reflection coefficient at the operating frequency based on a comparison result between a specified operating frequency and the detected first frequency;
Based on the locus of the input impedance of the patch antenna on the Smith chart obtained from the first result, calculate a feeding position of the patch antenna that brings the input impedance at the operating frequency closer to the center point of the Smith chart. do,
An antenna design program that allows a computer to perform processing. When the detected first frequency is higher than the operating frequency, the side length indicated by the design information is lengthened, and when the detected first frequency is lower than the operating frequency, the side length indicated by the design information is increased. shorten the side length,
The antenna design program according to claim 1, which causes the computer to execute the processing. When the circle that is the locus includes the center point, the power feeding position indicated by the design information is brought closer to the center of the patch,
If the circle does not include the center point, moving the power feeding position indicated by the design information away from the center of the patch;
The antenna design program according to claim 1 or 2, which causes the computer to execute the processing. In the Smith chart, the point of the input impedance at the operating frequency is the origin, a first coordinate axis passing through the origin and the center point, and a second coordinate axis passing through the origin and perpendicular to the first coordinate axis. system is set, and if the value of the first coordinate axis of the input impedance point at a second frequency different from the operating frequency is positive, it is determined that the circle includes the center point, and the first If the value of the coordinate axis is negative, determining that the circle does not include the center point;
The antenna design program according to claim 3, which causes the computer to execute the processing. updating the design information using the calculated side length and the power feeding position;
Detecting the first frequency, calculating the side length, calculating the power feeding position, and updating the design information are repeated based on a second result of electromagnetic field simulation using the updated design information. ,
The antenna design program according to any one of claims 1 to 4, which causes the computer to execute the processing. The computer is
Detecting a frequency at which the reflection coefficient of the patch antenna is minimum based on the results of an electromagnetic field simulation using design information of the patch antenna,
calculating a side length of a patch of the patch antenna that reduces the reflection coefficient at the operating frequency based on a comparison result between a specified operating frequency and the detected frequency;
Calculating a feeding position of the patch antenna that brings the input impedance at the operating frequency closer to the center point of the Smith chart, based on the locus of the input impedance of the patch antenna on the Smith chart obtained from the results;
Antenna design method. a storage unit that stores design information of a patch antenna and results of an electromagnetic field simulation using the design information;
Based on the result, the frequency at which the reflection coefficient of the patch antenna is the minimum is detected, and the reflection coefficient at the operating frequency is reduced based on a comparison result between a specified operating frequency and the detected frequency. Calculate the side length of the patch of the patch antenna, and bring the input impedance at the operating frequency closer to the center point of the Smith chart based on the locus of the input impedance of the patch antenna on the Smith chart obtained from the result. a processing unit that calculates a power feeding position of the patch antenna;
An information processing device having:

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