JP2008172641A - Antenna optimal design method, antenna optimal design program, record medium, antenna and information communication apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna design technique which optimizes an antenna shape parameter based on an evaluation value obtained by executing a directivity calculation step, a dispersion calculation step and an evaluation value calculation step sequentially, thereby improving a frequency dependency of directivity. <P>SOLUTION: In processing an evaluation function, a plurality of punctual coordinates set on a side face of an antenna are used as the antenna shape parameter and evaluation processing of this parameter is executed. The processing step of the evaluation function comprises STEP 1 which is the directivity calculation step, STEP 2 which is the dispersion calculation step and STEP 3 which is the evaluation value calculation step. These steps are sequentially executed, thereby obtaining the evaluation value. The antenna shape parameter is optimized based on this evaluation value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an antenna design method usable for mobile communication devices, small information terminals, and other wireless devices, an antenna designed by the method, a program for executing the method, and a recording medium recording the program More specifically, an antenna design method effective for reducing reflection loss in a wide band and improving the frequency dependence of directivity, an antenna designed by the method, and a program for implementing the method The present invention relates to a recording medium on which is recorded.

In recent years, with the rapid development of wireless communication technology, products using wireless technology have begun to spread widely. Wireless devices such as mobile communication terminals are required to reduce the size of antennas as devices become smaller. In addition, in order to cope with a plurality of communication systems and to cope with broadband transmission such as UWB, it is necessary to develop an antenna that has omnidirectionality in a horizontal plane and can be used in a wide band.
Conventionally known biconical antennas as shown in FIG. 12 and discone antennas as shown in FIG. 13 have been known as antennas having omnidirectionality in the horizontal plane and usable in a wide band. The biconical antenna of FIG. 12 has a configuration in which two conical elements 100 and 101 are connected to each other at the apex A of the cone, and the bottom surfaces B and C of the cone are arranged at both ends. The discone antenna of FIG. 13 has a structure in which the shape of the radiating element 102 of the monopole antenna is an inverted conical shape, and this shape is considered that one of the biconical antennas 103 has a disk shape. You can also. Studies have been made to increase the bandwidth by improving the structure of such an omnidirectional antenna in a horizontal plane.

FIG. 14 is a cross-sectional view of the antenna disclosed in Patent Document 1. In FIG. In this antenna, a part of the conical radiation electrode is composed of a low-conductivity member 104 or 105 such as rubber or elastomer containing a conductor, so that the reflected power to the power feeding part is reduced and the reflection loss is wideband. Techniques to be reduced are disclosed.
FIG. 15 is a cross-sectional view of the antenna disclosed in Patent Document 2. In this antenna, a technique is disclosed in which a reflection current is suppressed and reflection loss is reduced in a wide band by using a teardrop-shaped element 12 having a geometric combination of an inverted conical shape 12A and a spherical surface 12B as a radiating element. ing.
FIG. 16 shows an antenna disclosed in Patent Document 3. This antenna is composed of a conductor 202 whose outer peripheral surface of the radiating element is a semi-elliptical rotating body and a planar ground plane 203. In this antenna, the radiating element has a semi-elliptical rotator shape or a hemispherical shape, so that the antenna is miniaturized and widened.

As described above, in the horizontal plane omnidirectional antenna, studies have been made to widen the band in which the antenna can be used by reducing reflection loss over a wide band. However, a wideband antenna is required not only to have a low reflection loss in a wideband, but also to have little directivity change (variation) due to frequency. This is because when the directivity changes with frequency, the transfer function when observed in a specific direction changes with frequency.
JP 2004-201264 A JP 2004-129209 A JP 09-153727 A

However, the conventional techniques disclosed in Patent Documents 1, 2, and 3 have been improved so as to reduce reflection loss in a wide band, but no ingenuity has been made for the frequency dependence of directivity. . Also, an antenna design method for improving the frequency dependence of directivity has not been studied.
In view of such a problem, the present invention optimizes the antenna shape parameter based on the evaluation value obtained by sequentially executing the directivity calculation step, the dispersion calculation step, and the evaluation value calculation step. An object of the present invention is to provide an antenna design method for improving the dependency.

In order to solve this problem, the present invention provides a first rotating element-like element connected to a signal line, a second rotating element that is grounded, and the first element. A rotary member-like dielectric member provided around the element and the second element, and configured such that rotation center axes of the first element, the second element, and the dielectric member coincide with each other. An antenna optimum design method for designing an antenna shape by an optimization method, wherein a plurality of point coordinates set on side surfaces of the first element, the second element, and the dielectric member are antenna shape parameters, and the antenna As an evaluation function processing step for evaluating shape parameters by an optimization method, a directivity calculation step for calculating antenna directivity from a plurality of frequencies, and a dispersion calculation for calculating dispersion of each directivity at the plurality of frequencies. And an evaluation value calculation step of calculating an evaluation value based on the variance of each directivity at the plurality of frequencies, and sequentially executing the directivity calculation step, the variance calculation step, and the evaluation value calculation step The antenna shape parameter is optimized based on the evaluation value obtained by the above.
The antenna shape parameter may be any parameter that can be variable-converted into coordinates on the side surface of the first element, the second element, or the dielectric member. For example, the antenna shape parameter may be an inclination angle or a length of the side surface. There may be.
Further, as a parameter to be optimized, not only the antenna shape parameter but also a material of a member constituting the antenna may be used as a parameter if necessary. For example, the dielectric constant of the dielectric member can be used as a parameter.

ここで、Ｍは観測角度分割数、θ１は評価開始角度、θＭは評価終了角度、Ｗ（θ）は重み付け関数を表す。 The invention according to claim 2 is characterized in that the antenna shape parameter is set on at least one side surface of the first element, the second element, and the dielectric member.
In the invention according to claim 3, in the dispersion calculating step, an average value of gain at each observation angle that is an average directivity of the directivity calculated at the plurality of frequencies is calculated, and each of the calculated values at the plurality of frequencies is calculated. The directivity is a step of calculating a mean square value of gain deviations from the average directivity as variance.
In the variance calculation step, first, an average directivity of directivity G (θ, f), that is, an average value Gavg (θ) of gain with respect to the observation angle θ is calculated. Next, the variance V (f) of the directivity G (θ, f) from the average directivity Gavg (θ) is calculated for each frequency by the following equation.

Here, M is the number of observation angle divisions, θ1 is an evaluation start angle, θM is an evaluation end angle, and W (θ) is a weighting function.

この場合、分散Ｖ（ｆ）は以下の式で表される。

According to a fourth aspect of the present invention, in the variance calculation step, a target directivity that is a target for improving directivity is set in advance, and for each directivity calculated at the plurality of frequencies, the target directivity and This is a step of calculating a mean square value of gain deviations as a variance.
Regarding the calculation formula of the variance V (f), instead of the average directivity Gavg (θ), a target directivity Gtarget (θ) that is a target for improving directivity may be set arbitrarily. Further, as long as the dispersion of directivity can be quantified and the superiority or inferiority of characteristics can be compared, any calculation formula is possible without being limited to the above formula.
The invention according to claim 5 is characterized in that the variance calculation step calculates the variance by weighting according to the observation angle.
For example, the weighting function W (θ) can be determined as follows in the variance calculation step.

In this case, the variance V (f) is expressed by the following equation.

The invention according to claim 6 is characterized in that the variance calculation step calculates the variance within a predetermined observation angle range.
The invention according to claim 7 is characterized in that the evaluation value calculating step is a step of calculating an average value or a total value of the variances for each directivity calculated at the plurality of frequencies as an evaluation value.
In the evaluation value calculation step, an average value with respect to the frequency of the variance V (f) is calculated, and this is set as the evaluation value Score. N is the frequency division number, f1 is the evaluation start frequency, and fN is the evaluation end frequency.

The invention according to claim 8 is a reflection characteristic calculation step of calculating a frequency characteristic of reflection loss of the antenna, a reflection characteristic performance value calculation step of calculating a reflection characteristic performance value from the reflection characteristic, and the reflection characteristic performance value. And a second evaluation value calculating step of calculating an evaluation value using the above.
In the reflection characteristic calculation step, a calculation model is generated based on a shape parameter that is gene information possessed by each individual of the population, and the reflection characteristic S11 (f) is calculated using the FDTD method. Here, the reflection characteristic is the dependence of the reflection loss on the frequency, and is expressed as a function of the frequency f. In the reflection characteristic performance value calculation step, the reflection characteristic performance value P is calculated based on the calculated reflection characteristic S11 (f). The calculation formula of the reflection characteristic performance value P was determined so that the reflection characteristic performance value is smaller as the characteristic is better in the reflection band and the reflection loss is reduced.

The invention according to claim 9 is characterized in that the optimization method is a genetic algorithm.
A genetic algorithm was used as an optimization method for antenna shape parameters, a population of individuals having shape parameters as genetic information was generated, and shape parameters were optimized by repeating evaluation processing, selection processing, and mutation processing. .
A tenth aspect of the present invention is an antenna optimum design program for causing a computer to execute the antenna optimum design method according to any one of the first to ninth aspects.
The invention described in claim 11 is a recording medium in which the antenna optimum design program described in claim 10 is recorded in a computer-readable format.

The invention described in claim 12 is an antenna designed by the antenna optimum design method described in any one of claims 1 to 9.
According to a thirteenth aspect of the present invention, in the antenna according to the twelfth aspect, the shape of the first element connected to the signal line is a rotating body shape whose side faces are tapered, and x is the first element. When the position coordinates in the rotating body axis direction, a, b, and c are arbitrary constants, the shape of the taper is represented by a / (1 + exp (bx + c)), and the shape of the second element that is grounded is When x is the position coordinate of the second element in the direction of the axis of the rotator, and m and n are arbitrary constants, the shape of the side surface is represented by an elliptical expression n (1- (x / m) ² ) ^1/2. The dielectric member has a shape of an abacus-like bulge formed around the boundary between the first element and the second element.
Since the antenna designed using the antenna optimum design method of the present invention has improved directivity frequency dependency, a good communication state can be realized in a wide band.
According to a fourteenth aspect of the present invention, an information communication device includes the antenna according to the twelfth aspect.
Since the antenna obtained by the antenna optimum design method of the present invention is excellent in directivity and reflection characteristics in a wide band, a good communication state in a wide band can be realized by providing this antenna in an information communication device.

  According to the present invention, a plurality of point coordinates set on the side surfaces of the first element, the second element, and the dielectric member are used as antenna shape parameters, and by optimizing these parameters, the change in directivity due to frequency (variation) It is possible to design an antenna that suppresses).

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
[Example 1]
FIG. 1 is a cross-sectional view showing an antenna shape adopted as an initial model for optimal antenna design in the first embodiment of the present invention.
This antenna has a shape in which two conical elements face each other at the apex of a cone, and is conventionally known as a biconical antenna. A rotating dielectric member 45 having a relative dielectric constant of 2.0 is provided around these conical elements.
The antenna is fed from below by a coaxial line 42, the first element 40 is connected to the signal line 43 of the coaxial line 42, and the second element 41 is connected to the outer conductor (ground conductor) 44 of the coaxial line 42. .
In FIG. 1, the coordinates (x1, z1), (x2, z2), (x3, z3), (x4, z4), (x5, 6 points) set on the side surfaces of the first element 40 and the second element 41 are shown. z5), (x6, z6), and coordinates (x7, z7), (x8, z8), (x9, z9), (x10, z10) of four points set on the side surface of the dielectric member 45 are antenna shapes. It was a parameter. A genetic algorithm is used as an optimization method of the antenna shape parameter, a population of individuals having the shape parameter as gene information is generated, and the shape parameter is optimized by repeating the evaluation process, the selection process, and the mutation process. went.

本実施例の分散算出工程においては、重み付け関数Ｗ（θ）は以下のように定めた。

したがって、本実施例における分散Ｖ（ｆ）は（２）式で表される。

FIG. 2 is a process diagram of an evaluation function for executing the evaluation process of the first embodiment.
In the directivity calculation step of STEP 1, a calculation model is generated based on a shape parameter that is genetic information of each individual of the population, and directivity G (with a 1 GHz interval in a range of 10 GHz to 30 GHz using the FDTD method is used. θ, f) is calculated. Here, the directivity is a change in the gain G with respect to the observation angle, and is expressed as a function of the observation angle θ and the frequency f. As shown in FIG. 1, the observation angle θ is set such that the zenith direction of the antenna is θ = 0 ° and the horizontal direction is θ = 90 °.
In the dispersion calculation step of STEP2, first, the average directivity of the directivity G (θ, f) calculated in STEP1, that is, the average value Gavg (θ) of the gain with respect to the observation angle θ is calculated. Next, the dispersion V (f) of the directivity G (θ, f) from the average directivity Gavg (θ) is set for each frequency of f = 10, 15, 20, 25, and 30 GHz (frequency division number N = 5). Calculated by equation (1). Here, M is the number of observation angle divisions, θ1 is an evaluation start angle, θM is an evaluation end angle, and W (θ) is a weighting function.

In the variance calculation process of the present embodiment, the weighting function W (θ) is determined as follows.

Therefore, the variance V (f) in the present embodiment is expressed by equation (2).

The evaluation range of the observation angle θ was ± 40 ° from the horizontal direction (θ = 90 °), that is, θ = 50 to 130 ° (θ1 = 50 °, θM = 130 °). In the evaluation range of the observation angle θ, since the observation angle step is set to 1 °, the angle division number M = 81.
For the calculation formula of the variance V (f), a target directivity Gtarget (θ) that is a target for improving directivity may be arbitrarily set instead of the average directivity Gavg (θ). Further, as long as the dispersion of directivity can be quantified and the superiority or inferiority of characteristics can be compared, any calculation formula is possible without being limited to the above formula.

尚、（４）式に示すように前記評価値は、前記分散Ｖ（ｆ）の平均値ではなく合計値として算出しても良い。

ＳＴＥＰ１〜ＳＴＥＰ３を順に実行することにより算出された前記評価値は、その値が小さいほど周波数に対する指向性のばらつきが小さいことを示すので、指向性のばらつきを定量化し最適化により改善するための評価値として適している。また、本実施例における評価関数では、アンテナの指向性だけでなく反射特性についての評価も行う。
ＳＴＥＰ４の反射特性算出工程においては、母集団の各個体が持つ遺伝子情報である形状パラメータに基づいて計算モデルを生成し、ＦＤＴＤ法を使用して反射特性Ｓ１１（ｆ）を算出する。ここで反射特性とは、反射損失の周波数に対する依存性であり、周波数ｆの関数で表現される。
ＳＴＥＰ５の反射特性性能値算出工程では、ＳＴＥＰ４で算出した反射特性Ｓ１１（ｆ）に基づいて反射特性性能値Ｐを算出する。反射特性性能値Ｐの算出式は、広帯域で反射損失が低減された良好な特性であるほど、反射特性性能値が小さくなるように定めた。 In the evaluation value calculation step of STEP3, the average value for the frequency of the variance V (f) calculated in STEP2 is calculated by the equation (3), and this is set as the evaluation value Score. N represents the frequency division number, f1 represents the evaluation start frequency, and fN represents the evaluation end frequency. In this embodiment, N = 5, f1 = 10 GHz, and fN = f5 = 30 GHz.

Note that, as shown in the equation (4), the evaluation value may be calculated as a total value instead of an average value of the variance V (f).

The evaluation value calculated by sequentially executing STEP1 to STEP3 indicates that the smaller the value, the smaller the variation in directivity with respect to the frequency. Therefore, the evaluation for quantifying the variation in directivity and improving it by optimization Suitable as a value. In addition, the evaluation function in this embodiment evaluates not only the antenna directivity but also the reflection characteristics.
In the reflection characteristic calculation step of STEP4, a calculation model is generated based on the shape parameter that is gene information possessed by each individual of the population, and the reflection characteristic S11 (f) is calculated using the FDTD method. Here, the reflection characteristic is the dependence of the reflection loss on the frequency, and is expressed as a function of the frequency f.
In the reflection characteristic performance value calculation step of STEP5, the reflection characteristic performance value P is calculated based on the reflection characteristic S11 (f) calculated in STEP4. The calculation formula for the reflection characteristic performance value P was determined such that the better the characteristic with a reduced reflection loss in a wide band, the smaller the reflection characteristic performance value.

In the second evaluation value calculation step of STEP6, the reflection characteristic performance value P calculated in STEP5 is added to the evaluation value Score calculated in STEP3. In addition of the evaluation value and the reflection characteristic performance value, addition may be performed by multiplying one or both by appropriate coefficients a and b. The coefficients a and b can be appropriately set so that the optimization efficiency of the antenna optimum design method can be improved.
Score = Score × a + P × b (5)
The processing flow of the evaluation function for calculating the evaluation value from the reflection characteristic in addition to the evaluation of the directivity has been described above. In the evaluation function of the present invention, in addition to the evaluation of the directivity, the antenna weight, volume, etc. It is also possible to calculate the evaluation value by using the characteristic value.
In this way, in the evaluation value calculation process, the average value or total value of the variances of each directivity calculated at multiple frequencies is calculated as the evaluation value, and the evaluation values are used to compare the superiority and inferiority of the characteristics for optimization. Can be performed.

ここで、ｘは第１素子の回転体軸方向の位置座標であり、ａ、ｂ、ｃは定数である。
また、第２素子の側面形状は、以下のような楕円を表す（７）式により表現することが可能である。

ここで、ｘは第２素子の回転体軸方向の位置座標であり、ｍ、ｎは定数である。
また、第１素子および第２素子の境界の周囲に形成された誘電体部材の形状は、そろばん珠状の膨らみを有する形状である。 FIG. 3A is a diagram showing the shape of the antenna obtained by using the antenna optimum design method of this embodiment. As shown in FIG. 3B, the side shape of the first element of the antenna is a shape that can be expressed by the following functional form.

Here, x is a position coordinate of the first element in the rotating body axis direction, and a, b, and c are constants.
The side shape of the second element can be expressed by the following equation (7) representing an ellipse.

Here, x is the position coordinate of the second element in the direction of the rotating body axis, and m and n are constants.
The shape of the dielectric member formed around the boundary between the first element and the second element is a shape having an abacus bulge.

On the other hand, FIG. 4 is a diagram showing the shape of a conventional biconical antenna.
FIG. 5 is a diagram showing the frequency dependence of directivity of the antenna optimized according to the present invention (FIG. 3) and the conventional biconical antenna (FIG. 4). In FIG. 5, the vertical axis represents the observation angle, the horizontal axis represents the frequency, and the color shading indicates the intensity of the directivity gain. (A) is the directivity of the conventional biconical antenna, and (B) is the directivity of the antenna optimized by the present invention.
In the case of a conventional biconical antenna, the gain near 90 ° is large on the low frequency side below 20 GHz and the main radiation direction is almost 90 °, but the gain near 90 ° decreases on the high frequency side above 20 GHz. , Radiation direction has been divided up and down. On the other hand, in the optimized antenna, the main radiation direction is around 90 ° in a very wide band, and it can be confirmed that the frequency dependency of directivity is improved.

FIG. 6 is a diagram showing the frequency characteristics of the reflection loss of the conventional biconical antenna and the optimized antenna. In FIG. 6, the characteristics of the optimized antenna are indicated by solid lines, and the characteristics of the conventional biconical antenna are indicated by broken lines. With the optimized antenna, the reflection loss can be kept low over a wide band, and the characteristics are not deteriorated as compared with the conventional biconical antenna.
As described above, by using the antenna optimum design method described in the present embodiment, it becomes easy to design an antenna having both the reflection characteristics and the directivity frequency dependence characteristics, which were difficult with the conventional method. In addition, by using a genetic algorithm as an optimization method, efficient antenna optimum design is possible even when the number of shape parameters is large. Furthermore, since the antenna obtained by the antenna optimum design method described in this embodiment has excellent directivity and reflection characteristics in a wide band, it is possible to realize a good communication state in a wide band by providing the antenna in an information communication device. it can.

In this embodiment, the case of using a genetic algorithm as an optimization method has been described. However, in this antenna optimal design method, in addition to the genetic algorithm, the gradient method, steepest descent method, Newton method, experimental design method, simulated Various optimization methods such as annealing can be used, and can be determined appropriately according to the design object.
In addition, the antenna optimum design method described in the present embodiment can be realized by a personal computer, a workstation, or the like by a program that causes a computer to execute the method. In this case, a program capable of causing the computer to execute the method is a computer-readable recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, etc. Can be stored and distributed.

ここで、ｘは第１素子６０の回転体軸方向の位置座標であり、ａ、ｂ、ｃは定数である。
また、第２素子６１の側面形状は、以下のような楕円を表す式により表現することが可能である。

ここで、ｘは第２素子６１の回転体軸方向の位置座標であり、ｍ、ｎは定数である。
また、第１素子６０および第２素子６１の境界の周囲に形成された誘電体部材６５の形状は、そろばん珠状の膨らみを有する形状である。 [Example 2]
FIG. 7A is a diagram showing the shape of an antenna obtained by using the antenna optimum design method of this embodiment. As shown in FIG. 7B, the side surface shape of the first element 60 of the antenna is a shape that can be expressed by the following functional form.

Here, x is a position coordinate of the first element 60 in the rotating body axis direction, and a, b, and c are constants.
Further, the side surface shape of the second element 61 can be expressed by the following equation representing an ellipse.

Here, x is the position coordinate of the second element 61 in the rotating body axis direction, and m and n are constants.
The shape of the dielectric member 65 formed around the boundary between the first element 60 and the second element 61 is a shape having an abacus bulge.

FIG. 8 is a diagram showing the frequency dependence of the directivity of the antenna optimized according to the present invention (FIG. 7) and the conventional biconical antenna (FIG. 4). In FIG. 8, the vertical axis represents the observation angle, the horizontal axis represents the frequency, and the color shading indicates the intensity of the directivity gain. (A) is the directivity of the conventional biconical antenna, and (B) is the directivity of the antenna optimized by the present invention.
In the case of a conventional biconical antenna, the gain near 90 ° is large on the low frequency side below 20 GHz and the main radiation direction is almost 90 °, but the gain near 90 ° decreases on the high frequency side above 20 GHz. , Radiation direction has been divided up and down. On the other hand, in the optimized antenna, the main radiation direction is around 90 ° in a very wide band, and it can be confirmed that the frequency dependency of directivity is improved.

FIG. 9 is a diagram showing the frequency characteristics of the reflection loss of the conventional biconical antenna and the optimized antenna. In FIG. 9, the characteristics of the optimized antenna are indicated by solid lines, and the characteristics of the conventional biconical antenna are indicated by broken lines. With the optimized antenna, the reflection loss can be kept low over a wide band, and the characteristics are not deteriorated as compared with the conventional biconical antenna.
As described above, by using the antenna optimum design method described in the present embodiment, it becomes easy to design an antenna having both the reflection characteristics and the directivity frequency dependence characteristics, which were difficult with the conventional method. In addition, by using a genetic algorithm as an optimization method, efficient antenna optimum design is possible even when the number of shape parameters is large. Furthermore, since the antenna obtained by the antenna optimum design method described in this embodiment has excellent directivity and reflection characteristics in a wide band, it is possible to realize a good communication state in a wide band by providing the antenna in an information communication device. it can.

In this embodiment, the case of using a genetic algorithm as an optimization method has been described. However, in this antenna optimal design method, in addition to the genetic algorithm, the gradient method, steepest descent method, Newton method, experimental design method, simulated Various optimization methods such as annealing can be used, and can be determined appropriately according to the design object.
In addition, the antenna optimum design method described in the present embodiment can be realized by a personal computer, a workstation, or the like by a program that causes a computer to execute the method. In this case, a program capable of causing the computer to execute the method is a computer-readable recording medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, etc. Can be stored and distributed.

[Example 3]
FIG. 10 is a diagram illustrating the shape of the antenna in which the first element 60, the second element 61, and the dielectric member 65 of the antenna described in the second embodiment are smoothed. Even when the surface shape of the optimized antenna is rounded and smoothed as in the antenna shown in FIG. 10, it is possible to obtain the same characteristic improvement effect, and the reflection characteristics and directivity. It is possible to obtain an antenna excellent in both frequency dependency characteristics.
In addition, since the antenna described in this embodiment is excellent in directivity and reflection characteristics in a wide band, a good communication state in a wide band can be realized by providing the antenna in an information communication device.

[Example 4]
FIG. 11 is a diagram illustrating an example of an information device 71 including the antenna 70 of the present invention as described in the first and second embodiments. An information device 71 in FIG. 11 is a portable notebook personal computer (PC), and a wireless device 72 having an antenna 70 of the present invention is inserted into a slot 73 provided at any location of the information device 71. Yes. The information device 71 may be an information device such as a desktop PC, a personal digital assistant (PDA), and a mobile communication device such as a mobile phone. The wireless device 72 and the antenna 70 are incorporated in the information device 71. May be. The information device 71 is wirelessly connected to a network such as the Internet and an intranet by the wireless device 72, and can transmit and receive information to and from other devices connected to the network. Alternatively, the information device 71 may directly transmit / receive information to / from other devices without using a network. Information transmitted / received to / from other devices is transmitted / received in the form of an electromagnetic wave signal by an antenna 70 provided in the wireless device 72.
The antenna of the present invention is excellent in reflection characteristics and directivity frequency dependence in a wide band, so that it can be used in a broadband wireless communication system, and furthermore, a system that requires frequency hopping in a very wide band. Is advantageous in that the communication quality at each frequency used can be maintained.

The figure which shows the initial model of the antenna optimal design method which concerns on 1st Example. The processing flow figure of the evaluation function of the antenna optimum design method concerning the 1st example. The block diagram of the antenna which concerns on 1st Example. Sectional drawing of the conventional biconical antenna. The figure which showed the directivity of the antenna obtained by the antenna optimal design method based on 1st Example. The figure which showed the reflective characteristic of the antenna obtained by the antenna optimal design method based on 1st Example. The block diagram of the antenna which concerns on 2nd Example. The figure which showed the directivity of the antenna obtained by the antenna optimal design method based on 2nd Example. The figure which showed the reflective characteristic of the antenna obtained by the antenna optimal design method based on 2nd Example. The block diagram of the antenna which concerns on 3rd Example. The figure which showed the information communication apparatus which concerns on 4th Example. Schematic of a conventional biconical antenna. Schematic of a conventional discone antenna. The block diagram of the conventional antenna. The block diagram of the conventional antenna. The block diagram of the conventional antenna.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Reflection characteristic, 12 ... Teardrop-shaped element, 12A ... Reverse cone shape, 12B ... Spherical surface, 40, 60 ... First element, 41, 61 ... Second element, 42 ... Coaxial line, 43 ... Signal line, 45, 65 ... Dielectric member, 70 ... Antenna, 71 ... Information equipment, 72 ... Wireless device, 73 ... Slot, θ ... Observation angle, f ... Frequency, G (θ, f) ... Directionality (observation angle θ, frequency f Gain), Gavg (θ) ... average directivity, V (f) ... dispersion of G (θ, f) from Gavg (θ), N ... number of frequency divisions, f1 ... evaluation start frequency, fN ... evaluation end frequency, M: number of observation angle divisions, θ1: evaluation start angle, θM: evaluation end angle, P: reflection characteristic performance value, Score: evaluation value

Claims (14)

  A rotating body-shaped first element connected to the signal line; a grounded rotating body-shaped second element; and a rotating body-shaped dielectric member provided around the first element and the second element. An antenna optimum design method for designing the shape of an antenna configured so that rotation center axes of the first element, the second element, and the dielectric member coincide with each other by an optimization method, A plurality of point coordinates set on the side surfaces of one element, the second element, and the dielectric member are used as antenna shape parameters, and a plurality of evaluation function processing steps for evaluating the antenna shape parameters by an optimization method are used. A directivity calculating step of calculating antenna directivity from a plurality of frequencies; a dispersion calculating step of calculating dispersion of each directivity at the plurality of frequencies; and the dispersion of each directivity at the plurality of frequencies. An evaluation value calculation step for calculating an evaluation value, and the antenna shape parameter is optimized based on the evaluation value obtained by sequentially executing the directivity calculation step, the dispersion calculation step, and the evaluation value calculation step An antenna optimum design method characterized by the above.   The antenna optimum design method according to claim 1, wherein the antenna shape parameter is set on at least one side surface of the first element, the second element, and the dielectric member.   The dispersion calculating step calculates an average value of gain at each observation angle that is an average directivity of directivity calculated at the plurality of frequencies, and for each directivity calculated at the plurality of frequencies, the average directivity and The antenna optimum design method according to claim 1, wherein the method is a step of calculating a mean square value of gain deviations as a variance.   In the variance calculation step, target directivity that is a target for improving directivity is set in advance, and for each directivity calculated at the plurality of frequencies, a root mean square value of a deviation in gain from the target directivity is calculated. The antenna optimum design method according to claim 1, wherein the antenna optimum design method is a step of calculating as variance.   5. The antenna optimum design method according to claim 1, wherein the dispersion calculation step calculates the dispersion by weighting according to the observation angle. 6.   5. The antenna optimum design method according to claim 1, wherein the variance calculation step calculates the variance within a predetermined observation angle range. 6.   The said evaluation value calculation process is a process of calculating the average value or the total value of the said dispersion | distribution with respect to each directivity calculated by the said some frequency as an evaluation value, The said any one of Claim 1 thru | or 6 characterized by the above-mentioned. The antenna optimum design method described in 1.   A reflection characteristic calculation step of calculating a frequency characteristic of the reflection loss of the antenna, a reflection characteristic performance value calculation step of calculating a reflection characteristic performance value from the reflection characteristic, and an evaluation value is calculated using the reflection characteristic performance value The antenna optimal design method according to claim 1, further comprising a second evaluation value calculation step.   The antenna optimization design method according to claim 1, wherein the optimization method is a genetic algorithm.   An antenna optimum design program for causing a computer to execute the antenna optimum design method according to any one of claims 1 to 9.   A recording medium in which the antenna optimum design program according to claim 10 is recorded in a computer-readable format.   An antenna, which is designed by the antenna optimum design method according to any one of claims 1 to 9. The antenna according to claim 12, wherein the shape of the first element connected to the signal line is a rotating body shape whose side surface is tapered, and x is a position coordinate of the first element in the rotating body axis direction, When a, b, and c are arbitrary constants, the shape of the taper is a / (1 + exp (bx + c))
The shape of the second element, which is expressed by the following formula, is expressed by an equation n (where the shape of the side surface is an ellipse, where x is the position coordinate of the second element in the axis direction of the rotating body, and m and n are arbitrary constants. 1- (x / m) ² ) ^1/2
The antenna is characterized in that the dielectric member has a abacus-shaped bulge formed around the boundary between the first element and the second element.   An information communication device comprising the antenna according to claim 12.

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