JP2019186625A - Electric power conversion device and folded dipole antenna - Google Patents

Abstract

To provide an electric power conversion device in which a loss is reduced, and a folded dipole antenna.SOLUTION: An electric power conversion device includes: a first conductor having a length corresponding to a semi-wavelength in a free-space wavelength in a frequency of a received electric wave; a first element extended to a first end part along the first conductor from a first power supply point; and a second element extended to a second end part along the first conductor from the first power supply point and a second power supply point configuring a balanced terminal. The first conductor and a second conductor configuring the folded dipole antenna, and a rectification circuit connected to the first power supply point and the second power supply point are further included. A width of the first conductor is wider than that of the second conductor, and a length between the first end part and the second end part is a length corresponding to 0.6 λe to 0.8 λe when an electric length of the wavelength in the frequency is λe.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power conversion device and a folded dipole antenna.

  Conventionally, a balanced two-wire antenna, a balanced two-wire line, a rectifier circuit, and a DC output terminal are provided on one main surface of the substrate, and microwaves are received by the balanced two-wire antenna. There is a balanced two-wire line rectenna that outputs DC power to the DC output terminal based on a wave.

  The balanced two-wire antenna has a pair of antenna elements facing each other on one main surface of the substrate, and the balanced two-wire line is a central end of each antenna element on the one main surface of the substrate. And a pair of parallel lines extending in a direction orthogonal to the facing direction of each of the antenna elements.

  The rectifier circuit includes a DC blocking capacitor, a Schottky barrier diode disposed between the pair of lines, and a distance between the pair of lines separated from the Schottky barrier diode at a subsequent stage of the Schottky barrier diode. And a smoothing capacitor.

  The DC output terminal is connected to each of the pair of lines at the subsequent stage of the smoothing capacitor. The wavelength of the microwave is λg, and the predetermined interval is in the range of λg / 22.5 to λg / 14. It is characterized by setting.

  The balanced two-wire line rectenna further includes an input filter, and the input filter is provided in the pair of lines between the balanced two-wire antenna and the Schottky barrier diode ( For example, see Patent Document 1).

JP 2007-116515 A

  A conventional balanced two-wire rectenna (power converter) includes an input filter (filter) between a balanced two-wire antenna (antenna) and a rectifier circuit. This is because the capacitive component of the rectifier circuit is canceled by the inductive component of the filter to achieve impedance matching between the antenna and the rectifier circuit.

  By the way, the conventional power converter device has a problem that the loss is large because the loss of power in the filter occurs.

  Then, it aims at providing the power converter device and the return | turnback dipole antenna which reduced loss.

  The power conversion device according to the embodiment of the present invention includes a first conductor having a length corresponding to a half wavelength in a free space wavelength at a frequency of a received radio wave, and a first conductor from the first feeding point along the first conductor. A first element that extends to an end, and a second element that extends from the second feeding point that constitutes a balanced terminal with the first feeding point to the second end along the first conductor, A second conductor that forms a folded dipole antenna with the first conductor, and a rectifier circuit that is connected to the first feeding point and the second feeding point, and the width of the first conductor is that of the second conductor The length between the first end and the second end is wider than the width and corresponds to 0.6λe to 0.8λe, where λe is the electrical length of the wavelength at the frequency. .

  A power conversion device with reduced loss and a folded dipole antenna can be provided.

It is a figure which shows the power converter device 300 containing the return | turnback dipole antenna 100 of embodiment. It is a figure which expands and shows a part of FIG. 2 is a diagram illustrating a simulation model of a folded dipole antenna 100. FIG. 3 is a Smith chart showing frequency characteristics of impedance of a folded dipole antenna 100. 2 is a diagram illustrating a simulation model of a folded dipole antenna 100. FIG. 6 is a Smith chart showing the frequency characteristics of impedance of the rectifier circuit 200 as viewed from the folded dipole antenna 100 side. 3 is a Smith chart showing frequency characteristics of impedance of a folded dipole antenna 100. It is a figure which shows the folding | turning dipole antenna 100M of the modification of embodiment. It is a Smith chart which shows the frequency characteristic of the impedance of folding | turning dipole antenna 100M. It is a figure which shows the Smith chart obtained with the simulation model from which length Lf differs. It is a figure which shows the Smith chart obtained with the simulation model from which length Lf differs. 3 is a Smith chart showing the impedance of a folded dipole antenna 100. 3 is a Smith chart showing the impedance of a folded dipole antenna 100. 3 is a Smith chart showing the impedance of a folded dipole antenna 100. 3 is a Smith chart showing the impedance of a folded dipole antenna 100. 2 is a diagram illustrating a simulation model of a folded dipole antenna 100. FIG. 2 is a diagram illustrating a simulation model of a folded dipole antenna 100. FIG. 3 is a Smith chart showing frequency characteristics of impedance of a folded dipole antenna 100. 3 is a Smith chart showing frequency characteristics of impedance of a folded dipole antenna 100. FIG. 4 is a diagram showing a cross section of elements 110 and 120. It is a figure explaining the equivalent radius of elements 110 and 120. FIG.

  Embodiments to which the power conversion device and the folded dipole antenna of the present invention are applied will be described below.

<Embodiment>
FIG. 1 is a diagram illustrating a power conversion device 300 including a folded dipole antenna 100 according to an embodiment. Below, it demonstrates using an XYZ coordinate system.

  Power conversion device 300 includes a folded dipole antenna 100 and a rectifier circuit 200. The power converter 300 converts the high-frequency power of the radio wave received by the folded dipole antenna 100 into DC power by the rectifier circuit 200 and outputs it. Here, as an example, a case where the frequency of radio waves is 540 MHz will be described.

  The folded dipole antenna 100 has inductive impedance characteristics. Therefore, the power conversion device 300 can obtain impedance matching between the rectifier circuit 200 showing capacitive impedance and the folded dipole antenna 100 without including a filter in addition to the folded dipole antenna 100 and the rectifier circuit 200. it can. The details will be described below.

  The folded dipole antenna 100 includes a substrate 101 and elements 110 and 120. The substrate 101 is a substrate with low dielectric loss, such as a Teflon (registered trademark) substrate or a PPE (Polyphenylene Ether) substrate. The substrate 101 is not limited to a Teflon substrate or a PPE substrate, and may be, for example, a FR-4 (Flame Retardant type 4) standard wiring substrate, a substrate of another type, or a flexible substrate.

  The folded dipole antenna 100 can be manufactured, for example, by patterning a copper foil provided on the surface of the substrate 101. However, the folded dipole antenna 100 may be made of a metal other than copper.

  The element 110 has end portions 111 and 112 and is provided on the surface of the substrate 101. The element 110 is an example of a first conductor. The element 110 extends along the X axis with the ends 111 and 112 as both ends. The element 110 is arranged in parallel with the element 120.

The length of the folded dipole antenna 100 correspond to approximately half the wavelength of the free-space wavelength lambda ₀ of the electric waves received (about lambda _0/2) (length between the end portion 111 and 112) the length of the element 110 Set to This is because the element 110 corresponds to the entire length of the folded dipole antenna 100 (length from end to end in the X-axis direction).

Herein, the length that corresponds to the half wavelength of the free-space wavelength lambda ₀ of the radio wave (λ _0/2), is not limited to strictly radio free space wavelength lambda ₀ of the half wavelength (λ _0/2), folded in adjusting to function as a dipole antenna 100, is meant to include the length of the case is slightly shorter than a half wavelength (λ _0/2). Here, the length of the element 110, as an example, as a length corresponding to a half wavelength (λ _0/2), a 244mm corresponding to 0.44Ramuda ₀ in 540 MHz.

  In addition, the element width of the element 110 (the width in the Y-axis direction) is larger than the element width of the element 120. In the folded dipole antenna 100, the impedance is determined by the element width of the element 110 with respect to the element width of the element 120. By making the element width of the element 110 wider than the element width of the element 120, the impedance of the folded dipole antenna 100 can be increased.

  The element 120 includes elements 120 </ b> A and 120 </ b> B and is provided on the surface of the substrate 101. The element 120 is an example of a second conductor.

  The element 120A has a feeding point 121A and an end 122A. The element 120A is an example of a first element. The feeding point 121A is an example of a first feeding point. The end 122A is an example of a first end. The element 120A extends along the X axis between the feeding point 121A and the end 122A, and is parallel to the element 110. The feeding point 121 </ b> A is connected to the terminal 201 of the rectifier circuit 200.

  The length La between the end 122A and the midpoint between the feeding points 121A and 121B is 0.3 to 0.4 times the electrical length λe of the 540 MHz radio wave received by the folded dipole antenna 100 ( 0.3λe to 0.4λe).

  Here, the electrical length λe is the wavelength of an electromagnetic wave transmitted through a transmission medium such as the element 120A provided on the substrate 101, and the shortening rate varies depending on the relative dielectric constant of the substrate 101 and the like. With this shortening rate, the length (0.3λe to 0.4λe) of 0.3 to 0.4 times the electrical length λe of the radio wave is shortened.

  The element 120B has a feeding point 121B and an end 122B. The element 120B is an example of a second element. The feed point 121B is an example of a second feed point, and is arranged at a position that is point-symmetric with the feed point 121A, with an axis passing through the center of the element 110 in the X-axis direction and extending in the Y-axis direction as a symmetry axis. . For this reason, the length between the end 122B and the intermediate point between the feeding points 121A and 121B is also La. The end 122B is an example of a second end.

  The feeding points 121A and 121B are examples of balanced terminals. The terminals 201 and 202 of the rectifier circuit 200 are connected to the feeding points 121A and 121B. For example, the feeding points 121A and 121B and the terminals 201 and 202 of the rectifier circuit 200 may be connected by a copper foil pattern at the shortest distance. In FIG. 1, connection portions between the feeding points 121 </ b> A and 121 </ b> B and the terminals 201 and 202 of the rectifier circuit 200 are indicated by two broken lines.

  The element 120B extends along the X axis between the feeding point 121B and the end 122B, and is parallel to the element 110. The feeding point 121B is connected to the terminal 202 of the rectifier circuit 200.

  The element 120B is arranged so as to be symmetrical with the element 120A in a plan view with an axis passing through the center of the element 110 in the X-axis direction and extending in the Y-axis direction as an axis of symmetry.

  The length of the element 120B in the X-axis direction is equal to the length of the element 120A in the X-axis direction. That is, the length between the end 122B and the intermediate point between the feeding points 121A and 121B is set to a length (0.3λe to 0.4λe) that is 0.3 to 0.4 times the electrical length λe. Has been.

  For this reason, the length from the end portion 122A to the end portion 122B of the element 120 is 0.6 to 0.8 times the electrical length λe (0.6λe to 0.8λe). Note that the feeding point 121A and the feeding point 121B are actually arranged closer to each other than shown in FIG.

  Since the rectifier circuit 200 has a high impedance, it is necessary to increase the impedance of the folded dipole antenna 100 in order to match the capacitive impedance of the rectifier circuit 200 and the inductive impedance of the folded dipole antenna 100.

  For this reason, the element width (the width in the Y-axis direction) of the element 110 is made larger than the element width of the element 120. The rectification efficiency in the rectifier circuit 200 can be increased by conjugate matching between the impedance of the folded dipole antenna 100 and the impedance of the rectifier circuit 200.

  The rectifier circuit 200 includes terminals 201 and 202, capacitors 211, 212, 213, and 214, diodes 221, 222, 223, and 224, and output terminals 231 and 232. As an example, the rectifier circuit 200 is a Cockcroft-Walton rectifier circuit.

  Capacitors 211 and 212 are connected in series to the terminal 201, and capacitors 213 and 214 are connected in series to the terminal 202. In addition, the diodes 221, 222, 223, and 224 are connected to each other between the capacitors 211, 212, 213, and 214 as shown in FIG.

  The rectifier circuit 200 converts the high frequency power input from the folded dipole antenna 100 into a DC voltage and outputs the DC voltage from the output terminals 231 and 232. The impedance of the rectifier circuit 200 is capacitive due to the influence of the capacitance between the terminals of the diodes 221, 222, 223, and 224.

  Here, the name of the dimension of each part used in the following description will be described with reference to FIG. FIG. 2 is an enlarged view showing a part of FIG. In the following description, the widths Wa and Wb and the interval d are used in addition to the lengths La and Lb described above.

  The width Wa is the width of the element 120 (the width in the Y-axis direction), and is 0.2 mm as an example. The width Wb is the width of the element 110 (the width in the Y-axis direction), and is 8.0 mm as an example. The distance d is the distance between the elements 110 and 120 in the Y-axis direction. The interval between the feeding points 121A and 121B is 2 mm as an example.

  FIG. 3 is a diagram illustrating simulation models 100A1 to 100F1 of the folded dipole antenna 100. In FIG. 3, the reference numerals of the respective parts are omitted.

  In the simulation models 100A1 to 100F1 shown in FIGS. 3A to 3F, the lengths La are set to 0.1λe, 0.2λe, 0.3λe, 0.4λe, 0.5λe, and 0.6λe, respectively. Has been. In the simulation models 100D1 to 100F1, the length of the substrate in the X-axis direction is longer than that of the substrate 101 shown in FIG.

The dielectric constant εr of the substrate 101 is 3.4, the height (thickness in the Z-axis direction) h is 0.75 mm, the distance d between the elements 110 and 120 in the Y-axis direction is 4 mm, and the X-axis direction of the element 110 is The length Lb is 244 mm. 244 mm is 0.44 times the free space wavelength λ ₀ of the 540 MHz radio wave received by the folded dipole antenna 100.

  FIG. 4 is a Smith chart showing the impedance when the frequency of the radio wave received by the folded dipole antenna 100 is changed. In the Smith chart shown in FIG. 4, the resistance value at the center of the horizontal axis (the center point of the Smith chart) is 2 kΩ. This is the same in other Smith charts shown below.

  4A to 4F, the length La is set to 0.1λe, 0.2λe, 0.3λe, 0.4λe, 0.5λe, and 0.6λe, respectively, and the frequency of the radio wave is 400 MHz. The Smith chart at the time of changing from 700 MHz to 700 MHz is shown.

  When the length La shown in FIG. 4A is 0.1λe, as the frequency increases, the isoresistance circle passing through the short-circuit point (the left end of the horizontal axis) moves from about −135 degrees to about −160 degrees. A trajectory was obtained.

  In the case where the length La shown in FIG. 4B is 0.2λe, as the frequency increases, a trajectory moving from about −166 degrees to about 173 degrees of the isoresistance circle passing through the short-circuit point is obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  In the case where the length La shown in FIG. 4C is 0.3λe, as the frequency increases, a trajectory moving from about 180 degrees to about 140 degrees of the isoresistance circle passing through the short-circuit point is obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the length La shown in FIG. 4 (D) is 0.4λe, the arc is drawn from about 165 degrees to about 180 degrees slightly inside the isoresistance circle passing through the short-circuit point as the frequency increases. A trajectory moving from about 180 degrees to about 35 degrees was obtained.

  When the length La shown in FIG. 4E is 0.5λe, a circle from about −160 degrees to about −130 degrees further inside the locus shown in FIG. 4D as the frequency increases. A trajectory like drawing was obtained.

  When the length La shown in FIG. 4 (F) is 0.6λe, a trajectory such that the trajectory shown in FIG. 4 (E) is further shrunk further inward and rotated once is obtained.

  From the above results, when the length La shown in FIGS. 4C and 4D is 0.3λe and 0.4λe, it rotates clockwise in the upper half area of the Smith chart circle, and is inductive. A trajectory representing was obtained. From this, it was found that 0.3λe to 0.4λe is an appropriate range for the length La in order to make the impedance of the folded dipole antenna 100 inductive.

  FIG. 5 is a diagram showing simulation models 100A2 to 100E2 of the folded dipole antenna 100. FIG. In FIG. 5, the reference numerals of the respective parts are omitted.

  In the simulation models 100A2 to 100E2 shown in FIGS. 5A to 5E, the lengths La are set to 0.32λe, 0.34λe, 0.36λe, and 0.38λe, respectively.

The dielectric constant εr of the substrate 101 is 3.4, the height (thickness in the Z-axis direction) h is 0.75 mm, the distance d between the elements 110 and 120 in the Y-axis direction is 4 mm, and the X-axis direction of the element 110 is The length Lb is 244 mm. 244 mm is 0.44 times the free space wavelength λ ₀ of the 540 MHz radio wave received by the folded dipole antenna 100.

  Here, a Smith chart showing the frequency characteristics of the impedance of the rectifier circuit 200 will be described with reference to FIG. FIG. 6 is a Smith chart showing the frequency characteristics of the impedance of the rectifier circuit 200 as viewed from the folded dipole antenna 100 side. FIG. 6 shows a Smith chart when the frequency of the radio wave is changed from 400 MHz to 700 MHz.

  As shown in FIG. 6, the impedance of the rectifier circuit 200 is a locus that moves from about −140 degrees to about −153 degrees, and it has been confirmed that the impedance shows capacitive impedance.

  Here, by realizing a folded dipole antenna 100 having an inductive impedance that is conjugate-matched with a rectifier circuit 200 having a capacitive impedance having frequency characteristics as shown in FIG. 6, the rectification efficiency in the rectifier circuit 200 is increased. Increase. Note that the conjugate matching here means that the capacitive component of the impedance of the rectifier circuit 200 and the inductive component of the impedance of the folded dipole antenna 100 are offset by a complex conjugate relationship. .

  FIG. 7 is a Smith chart showing the impedance when the frequency of the radio wave received by the folded dipole antenna 100 is changed. 7A to 7E, the length La is set to 0.32λe, 0.34λe, 0.35λe, 0.36λe, and 0.38λe, respectively, and the radio wave frequency is changed from 400 MHz to 700 MHz. The Smith chart when it is made to show is shown. FIG. 7F shows a Smith chart of a simulation model 100D1 (see FIG. 3D) having a length La of 0.4λe. This is the same as that shown in FIG.

  When the length La shown in FIG. 7 (A) is 0.32λe, as the frequency increases, from the vicinity of the short-circuit point to slightly inside the iso-resistance circle passing through the short-circuit point from about 180 degrees to about 170 degrees. After entering, it moved up to about 120 degrees along an isoresistance circle passing through the short-circuit point. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the length La shown in FIG. 7B is 0.34λe, after the kink apex is formed at about 170 degrees from the point of about 175 degrees near the short circuit point as the frequency increases, A trajectory moving from about 165 degrees to about 100 degrees along an isoresistance circle passing through is obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the length La shown in FIG. 7C is 0.35λe, after the kink apex is formed at about 170 degrees from the point of about 175 degrees near the short circuit point as the frequency increases, A trajectory moving from about 160 degrees to about 95 degrees along an iso-resistance circle passing through is obtained. As the frequency increased, it was a trajectory that gradually entered the inside of the isoresistance circle passing through the short circuit point. The kink apex was larger than when the length La was 0.34λe.

  When the length La shown in FIG. 7D is 0.36λe, after the kink apex is formed at about 170 degrees from the point of about 175 degrees near the short circuit point as the frequency increases, A trajectory moving from about 160 degrees to about 85 degrees along an iso-resistance circle passing through is obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little. The kink apex was larger than the length La of 0.34λe and 0.35λe.

  When the length La shown in FIG. 7 (E) is 0.38λe, as the frequency increases, from the point of about 170 degrees, the kink apex is formed, and then along the isoresistance circle passing through the short-circuit point. A trajectory moving from 160 degrees to about 65 degrees was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the length La shown in FIG. 7 (F) is 0.40λe, compared to the locus shown in FIG. 7 (E) where the length La is 0.38λe, the locus of the first kink is further expanded, and the frequency Along with the increase, a locus moving from about 160 degrees to about 35 degrees along the isoresistance circle passing through the short-circuiting point was obtained after forming the kink apex from the point of about 165 degrees. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  From the above results, all the trajectories of FIGS. 7A to 7F are trajectories that rotate clockwise in the upper half region of the Smith chart, have kink vertices, and exhibit inductivity. . For example, considering an application to communication with a wide frequency band, an impedance characteristic having a kink apex in the upper half region of the Smith chart circle is effective. However, from the standpoint that conjugate matching can be obtained in a wide band with the capacitive impedance of the rectifier circuit 200 having frequency characteristics as shown in FIG. 6, among these, FIG. 7B, FIG. 7C, and FIG. It has been found that the case where the indicated length La is 0.34λe to 0.36λe is particularly good.

  From the above, it has been found that the length La is particularly good when the length La is in the range of 0.32λe to 0.4λe.

  As described above, the folded dipole antenna 100 according to the embodiment has an inductive impedance. Therefore, if the inductive impedance of the folded dipole antenna 100 is adjusted to match the capacitive impedance of the rectifier circuit 200, the power conversion device 300 does not include a low-pass filter. In other words, the impedance of the folded dipole antenna 100 and the impedance of the rectifier circuit 200 may be conjugated.

  Since the power conversion device 300 does not include a low-pass filter between the folded dipole antenna 100 and the rectifier circuit 200, loss can be reduced. That is, according to the embodiment, it is possible to provide the folded dipole antenna 100 and the power conversion device 300 with reduced loss.

  In the above description, the rectifier circuit 200 is a cockcroft-Walton type rectifier circuit. However, the rectifier circuit 200 is not limited to the cockcroft-Walton type. Any type of rectifier circuit that can rectify the high-frequency power output from the folded dipole antenna 100 to DC power may be used.

  In the above description, the folded dipole antenna 100 receives 540 MHz radio waves as an example. However, the frequency is not limited to 540 MHz, and the inductive impedance of the folded dipole antenna 100 is adjusted according to the desired frequency. do it. Such adjustment can be performed mainly by setting the lengths and intervals of the elements 110 and 120 at the design stage.

  FIG. 8 is a diagram illustrating a folded dipole antenna 100M according to a modification of the embodiment. The folded dipole antenna 100M includes a substrate 101M and elements 110 and 120M. Here, the same components as those of the folded dipole antenna 100 shown in FIG.

  The substrate 101M is wider in the Y-axis direction than the substrate 101 shown in FIG. This corresponds to the element 120M.

  The element 120M includes elements 120MA and 120MB, and is provided on the surface of the substrate 101M. The element 120M is an example of a second conductor.

  Elements 120MA and 120MB are obtained by adding extensions 123A and 123B to elements 120A and 120B shown in FIG. 1, respectively. The extensions 123A and 123B are connected to the feeding points 121A and 121B, respectively, and extend to the terminals 123A1 and 123B1 on the Y axis negative direction side. The extension portions 123A and 123B are parallel to each other and parallel to the Y axis. The extensions 123A and 123B are balanced lines. The length of the extension parts 123A and 123B is Lf. The extension parts 123A and 123B are examples of a first extension line and a second extension line, respectively.

  The terminals 123A1 and 123B1 are positioned in front of the long side extending in the X-axis direction on the Y-axis negative direction side of the substrate 101M. As an example, the length La is 0.35λe, and the lengths of the extensions 123A and 123B are 20 mm. The terminals 123A1 and 123B1 are connected to the terminals 201 and 202 of the rectifier circuit 200.

  FIG. 9 is a Smith chart showing the frequency characteristics of impedance when the frequency of the radio wave received by the folded dipole antenna 100M is changed. FIG. 9A shows the frequency characteristics of impedance when the frequency of the radio wave received by the folded dipole antenna 100M is changed from 400 MHz to 700 MHz. FIG. 9B shows the frequency characteristics of the impedance of the simulation model 100C2 (see FIG. 5C). This is the same as that shown in FIG.

  The trajectory of the folded dipole antenna 100M shown in FIG. 9A is such that, as the frequency increases, a kink apex is formed at about 165 degrees from a point of about 170 degrees near the short circuit point, and then passes through the short circuit point. A trajectory moving from about 160 degrees to about −110 degrees along the resistance circle was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little. The kink vertex was shifted slightly above the locus of the simulation model 100C2 shown in FIG. 9B, and a large kink vertex was obtained. This indicates that the kink vertex of the folded dipole antenna 100M is more inductive than the kink vertex of the simulation model 100C2. The trajectory of the simulation model 100C2 shown in FIG. 9B is better conjugate-matched with the input impedance of the rectifier circuit 200 than the folded dipole antenna 100M shown in FIG. 9A. It was found that a sufficiently good trajectory can be obtained even with the folded dipole antenna 100M shown in A).

  Therefore, it is possible to provide a power conversion device with reduced loss and a folded dipole antenna 100M.

  FIGS. 10 and 11 are Smith charts showing the frequency characteristics of impedance when the radio wave frequency is changed from 400 MHz to 700 MHz in a simulation model of the folded dipole antenna 100M in which the lengths Lf of the extension portions 123A and 123B are different. Specifically, a Smith chart of a simulation model having a length Lf of λe / 50 to λe / 6 was obtained.

The length La of the simulation model is 0.35λe, the dielectric constant εr of the substrate 101 is 3.4, the height (thickness in the Z-axis direction) h is 0.75 mm, and the elements 110 and 120 in the Y-axis direction. The distance d is 4 mm, and the length Lb of the element 110 in the X-axis direction is 244 mm. 244 mm is 0.44 times the free space wavelength λ ₀ of the 540 MHz radio wave. The electric length λe and the free-space wavelength lambda ₀ is the value at 540 MHz.

  FIG. 10A shows the frequency characteristics (same as FIG. 7C) of the impedance of the simulation model 100C2 (see FIG. 5C) that does not have the extensions 123A and 123B. Here, for convenience of explanation, the simulation model 100C2 (see FIG. 5C) is shown as a simulation model having a length Lf of 0 mm.

  When the length Lf shown in FIG. 10B is λe / 50, as the frequency increases, the kink apex is formed at about 168 degrees from the point of about 170 degrees near the short circuit point, and then the short circuit point. A trajectory moving from about 160 degrees to about −40 degrees along an iso-resistance circle passing through is obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little. The kink apex was larger than when the length Lf was 0 mm.

  When the length Lf shown in FIGS. 10C to 10F is λe / 40, λe / 30, λe / 20, and λe / 18, as the frequency increases, the length Lf is about 170 degrees near the short-circuit point. From the point, after forming a kink apex at about 165 degrees, move from about 160 degrees to about -70 degrees, about -105 degrees, about -138 degrees, and about -145 degrees along the isoresistance circle passing through the short-circuit point. A trajectory was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little. As the length Lf becomes longer, the kink apex gradually moves to the upper side of the horizontal axis along the isoresistance circle, and the inductivity tends to increase.

  When the length Lf shown in FIGS. 11 (A) to 11 (C) is λe / 16, λe / 14, and λe / 12, as the frequency increases, from the point of about 165 degrees near the short circuit point, After forming the kink apex at 165 degrees, a trajectory moving from about 160 degrees to about -150 degrees, about -155 degrees, and about -165 degrees along the isoresistance circle passing through the short-circuit point was obtained. As the frequency increased, the arc-shaped trajectory after drawing the kink apex tended to decrease.

  When the length Lf shown in FIGS. 11D to 11F is λe / 10, λe / 8, and λe / 6, as the frequency increases, from the point of about 160 degrees near the short-circuit point, Although a kink apex was obtained near the axis, a clearly inductive trajectory was not obtained.

  As mentioned above, when attaching extension part 123A, 123B, it turned out that it is preferable that length Lf is (lambda) e / 20 or less.

  12 to 15 are Smith charts showing impedance frequency characteristics when the frequency of the radio wave received by the folded dipole antenna 100 is changed. 12 to 15 show impedance frequency characteristics when the distance d between the elements 110 and 120 in the Y-axis direction is set from λe / 10 to λe / 6000 and the frequency of the radio wave is changed from 400 MHz to 700 MHz. It is a Smith chart.

The substrate 101 has a dielectric constant εr of 3.4, a height (thickness in the Z-axis direction) h of 0.75 mm, a length La of 0.35λe, and Lb of 244 mm (0.44λ ₀ ). In addition, since λe / 100 is 5.56 mm and λe / 200 is 2.78 mm, the distance d becomes 4 mm, which is approximately λe / 139.

  When the distance d shown in FIGS. 12A to 12C is λe / 10, λe / 20, and λe / 30, along the isoresistance circle passing through the short-circuit point from about 175 degrees as the frequency increases. Trajectories moving to about -50 degrees, about -25 degrees, and about 0 degrees were obtained. When the frequency increased from 400 MHz, it was a trajectory showing inductivity and entering inside, but the kink apex was not obtained.

  When the distance d shown in FIGS. 12D to 12F is λe / 40, λe / 50, and λe / 60, as the frequency increases, the distance d increases from about 175 degrees near the short-circuit point to about 165 degrees. After forming the kink apex at a degree, a trajectory moving from about 160 degrees to about 20 degrees, about 35 degrees, and about 45 degrees along the isoresistance circle passing through the short-circuit point was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the distance d shown in FIGS. 13A to 13F is λe / 70, λe / 80, λe / 90, λe / 100, λe / 200, and λe / 300, as the frequency increases, the short-circuit point After forming a kink apex at about 165 degrees from a point of about 175 degrees near, about 160 degrees to about 55 degrees, about 60 degrees, about 67 degrees, about 72 degrees along the isoresistance circle passing through the short circuit point The trajectory moving up to about 95 degrees and about 104 degrees was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the distance d shown in FIGS. 14A to 14F is λe / 400, λe / 500, λe / 600, λe / 700, λe / 800, and λe / 900, the short-circuit point increases as the frequency increases. Up to about 110 degrees, about 113 degrees, about 115 degrees, about 118 degrees, about 118 degrees, about 123 degrees along the iso-resistance circle through the short circuit point after forming the kink apex from about 175 degrees near A moving trajectory was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  When the distance d shown in FIGS. 15A to 15F is λe / 1000, λe / 2000, λe / 3000, λe / 4000, λe / 5000, and λe / 6000, the short-circuit point increases as the frequency increases. After the kink apex is formed from the point of about 175 degrees near, about 125 degrees, about 135 degrees, about 142 degrees, about 128 degrees, about 150 degrees, about 152 degrees along the isoresistance circle passing through the short circuit point A moving trajectory was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  From the above, it can be seen that when the distance d is λe / 40 or less, a kink vertex is obtained and an inductive locus is obtained. In addition, it can be seen that when the distance d is around λe / 40 to λe / 1000, the kink apex is obtained and the inductive locus is clearly obtained, which is particularly good. Further, λe / 1000 is 0.56 mm, and λe / 6000 is 0.09 mm.

  The distance d may be λe / 1000. For example, when the elements 110 and 120 are manufactured by etching, the distance d may be set in relation to the limit of the etching process.

  16 and 17 are diagrams showing simulation models 100A3 to 100F3 and 100A4 to 100F4 of the folded dipole antenna 100. FIG. In FIG. 16, the reference numerals of the respective parts are omitted.

  In simulation models 100A3 to 100F3 and 100A4 to 100F4 shown in FIGS. 16A to 16E and FIGS. 17A to 17F, at least a part of the element 120 has a meander shape.

  In the simulation model 100A3 shown in FIG. 16A, the entire element 120 is a meander portion having a meander shape, and the length La is 0.41λe. The meander part is 6 mm in the X-axis direction and 4 mm in the Y-axis direction, and the number of periods of the meander part is 10 for both the elements 120A and 120B.

  In simulation models 100B3 to 100F3 and 100A4 to 100F4 shown in FIGS. 16 (B) to 16 (F) and FIGS. 17 (A) to (F), both ends of the element 120 are meander portions having a meander shape. In the element 120, a section parallel to the element 110 in the X-axis direction is linear, and a section outside the element 110 in the X-axis direction has a meander shape.

  The meander parts of the simulation models 100B3 to 100F3 are 4 mm in the X-axis direction and 2 mm in the Y-axis direction, and the number of periods of the meander parts is 5, 6, 7, 8, and 9 for both the elements 120A and 120B. . The lengths La of the simulation models 100B3 to 100F3 are 0.369λe, 0.393λe, 0.418λe, 0.443λe, and 0.467λe, respectively.

  Further, the meander part of the simulation models 100A4 to 100F4 is 4 mm in the X-axis direction and 2 mm in the Y-axis direction, and the number of periods of the meander part is 10, 11, 12, 13, 14 for both the elements 120A and 120B. , 15. The lengths La of the simulation models 100A4 to 100F4 are 0.492λe, 0.516λe, 0.541λe, 0.566λe, 0.590λe, and 0.615λe, respectively.

The dielectric constant εr of the substrate 101 is 3.4, the height (thickness in the Z-axis direction) h is 0.75 mm, the distance d between the elements 110 and 120 in the Y-axis direction is 4 mm, and the X-axis direction of the element 110 is The length Lb is 244 mm (0.44λ ₀ ).

  18 and 19 are Smith charts showing impedance frequency characteristics when the frequency of the radio wave received by the folded dipole antenna 100 is changed. FIGS. 18A to 18F and FIGS. 19A to 19F show impedances when the radio wave frequency is changed from 400 MHz to 700 MHz in the simulation models 100A3 to 100F3 and 100A4 to 100F4, respectively. Shows frequency characteristics.

  In the Smith chart of the simulation model 100A3 shown in FIG. 18 (A), as the frequency increases, from the vicinity of the short-circuit point to about 180 degrees of the iso-resistance circle passing through the short-circuit point, along the iso-resistance circle passing through the short-circuit point. A trajectory moving up to about 30 degrees was obtained. As the frequency increases, the trajectory shows inductivity but does not have a kink apex.

  In the Smith charts of the simulation models 100B3 and 100C3 shown in FIGS. 18B and 18C, as the frequency increases, the kink apex is formed though entering slightly from about 180 degrees of the isoresistance circle passing through the short-circuit point. Without this, a trajectory moving up to about 116 degrees and about 106 along the isoresistance circle passing through the short-circuit point was obtained.

  In the Smith charts of the simulation models 100D3, 100E3, and 100F3 shown in FIGS. 18D, 18E, and 18F, a kink vertex is formed from a point of about 175 degrees near the short-circuit point as the frequency increases. Later, a trajectory moving from about 160 degrees to about 95 degrees, about 80 degrees, and about 65 degrees along an isoresistance circle passing through the short-circuit point was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  In the Smith charts of the simulation models 100A4 and 100B4 shown in FIGS. 19A and 19B, a kink apex is formed from a point of about 170 degrees near the short-circuit point as the frequency increases, and then passes through the short-circuit point. A trajectory moving up to about 45 degrees and about 25 degrees along the isoresistance circle was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  In the Smith charts of the simulation models 100C4, 100D4, 100E4, and 100F4 shown in FIGS. 19C, 19D, 19E, and 19F, as the frequency increases, around 175 degrees near the short circuit point. A trajectory that formed a kink apex and moved to about 0 degrees, about −30 degrees, about −55 degrees, and about −80 degrees along the isoresistance circle passing through the short-circuit point was obtained. As the frequency increased, it was a trajectory that entered the inside of the iso-resistance circle passing through the short-circuit point little by little.

  As described above, the simulation models 100D3, 100E3, and 100F3 shown in FIGS. 18D to 18F and the simulation models 100A4 and 100B4 shown in FIGS. 19A and 19B have kink vertices at a desired frequency. And it was found to show an inductive trajectory.

  Since the length La of these simulation models 100D3, 100E3, 100F3, 100A4, and 100B4 is 0.418λe to 0.516λe, when the meander portions are provided at both ends of the element 110, the length La is about 0. It turned out that it is good to set to 42 (lambda) e-0.52 (lambda) e. Further, by providing the meander portion, the length in the X direction of the substrate necessary for obtaining the same effect can be shortened, so that the dimension in the X direction of the folded dipole antenna and the power conversion device using the folded dipole antenna can be reduced. it can.

  Next, the skin effect and equivalent radius in the elements 110 and 120 will be described with reference to FIGS.

  FIG. 20 is a view showing a cross section of the elements 110 and 120. 20A and 20B show cross sections of the elements 110 and 120 obtained along the Y axis. 20A and 20B show a substrate 101 on which the folded dipole antenna 100 is mounted. In FIGS. 20A and 20B, portions where high-frequency current flows in the elements 110 and 120 are shown in gray. In the portion indicated by gray, for example, a current of 540 MHz flows due to the skin effect.

  In FIG. 20A, the thickness of the element 120 is t1, the element width is w1, the thickness of the element 110 is t1, and the element width is w2. In FIG. 20B, the thickness of the element 120 is t2, the element width is w1, the thickness of the element 110 is t2, and the element width is w2. The thickness t1 is thicker than the thickness t2.

  As an example, the thickness t1 of the element 120 shown in FIG. 20A is 18 μm, the element width w1 is 0.1 mm to 0.5 mm, the thickness of the element 110 is t1 is 18 μm, and the element width w2 is 2 mm to 8 mm. is there. 20B, the thickness t2 of the element 120 is twice the skin depth, the element width w1 is 0.1 mm to 0.5 mm, the thickness of the element 110 is t2 is twice the skin depth, The element width w2 is 2 mm to 8 mm. Moreover, when the frequency of the electromagnetic wave received by the folded dipole antenna 100 is 540 MHz, the skin depth is 3 μm, and when it is 2.4 GHz, the skin depth is 1 μm.

  The elements 110 and 120 are produced by patterning a copper foil formed on the surface of the substrate 101 by an etching process such as wet etching. In the etching process, the upper surfaces of the elements 110 and 120 are smooth because they are protected by a mask. However, since the side surfaces of the elements 110 and 120 are shaved by the etching process, the smoothness is lower than the upper surface, and the surface. Is rough. For this reason, the side surfaces of the elements 110 and 120 have a higher frequency resistance than the upper surface, so that the loss increases.

  As shown in FIG. 20A, when the elements 110 and 120 are made thicker, the ratio of the current flowing through the side surfaces of the elements 110 and 120 than in the case where the elements 110 and 120 are made thin as shown in FIG. Will increase. In particular, this tendency is remarkable in the element 120 having a narrow element width.

  FIG. 21 is a diagram for explaining the equivalent radii of the elements 110 and 120. Here, the equivalent radius of the element 120 is r1, the equivalent radius of the element 110 is r2, and the distance between the elements 110 and 120 (the distance between the centers of the element widths of the elements 110 and 120) is d1. Note that the thickness of the element 120 is t1, the element width is w1, the thickness of the element 110 is t1, and the element width is w2.

The equivalent radii r1 and r2 can be expressed by equations (1) and (2), respectively, and the impedance step-up ratio (n ² ) can be expressed by equation (3).

  In order to reduce the current flowing through the side surface of the element 120 and reduce the loss, it is desirable that the current flowing through the side surface is less than 20% of the total. When the ratio of the equivalent radius r1 of the element 120 obtained by Expression (1) to the current flowing through the side surface is obtained, it is desirable that (0.34t1) / (0.34t1 + 0.25w1) <0.2 is satisfied.

  Although the equivalent radii of the elements 110 and 120 have been described here, the elements 120 and 120 have the same size and are arranged line-symmetrically in a plan view. Therefore, the equivalent radius of the element 120 is equivalent to that of the element 120. Equal to radius.

  The power conversion device and the folded dipole antenna according to the exemplary embodiment of the present invention have been described above. However, the present invention is not limited to the specifically disclosed embodiment, and Various modifications and changes can be made without departing from the scope.

100, 100M Folded Dipole Antenna 101, 101M Substrate 110, 120, 120A, 120B, 120M, 120MA, 120MB Element 111, 112 End 121A, 121B Feed Point 122A, 122B End 123A, 123B Extension 123A1, 123B1 Terminal 200 Rectification Circuit 300 power converter

Claims (11)

A first conductor having a length corresponding to a half wavelength in a free space wavelength at a frequency of a received radio wave;
A first element extending from the first feeding point along the first conductor to the first end, and a second element along the first conductor from the second feeding point that forms a balanced terminal with the first feeding point. A second element extending to an end, and forming a folded dipole antenna with the first conductor;
A rectifier circuit connected to the first feeding point and the second feeding point,
The width of the first conductor is wider than the width of the second conductor,
The length between the first end portion and the second end portion is 0.6λe to 0.8λe, where the electrical length of the wavelength at the frequency is λe.   The power converter according to claim 1, wherein an interval between the first conductor and the second conductor is 1/40 or less of an electrical length λe of the wavelength.   The first extension line and the second extension line that are respectively connected to the first feeding point and the second feeding point and extend in a direction away from the second conductor in plan view. Power converter.   4. The power converter according to claim 3, wherein lengths of the first extension line and the second extension line are 1/20 or less of an electrical length λe of the wavelength.   The power converter according to any one of claims 1 to 4, wherein the second conductor has a meander part.   The power converter according to any one of claims 1 to 4, wherein the second conductor has meander portions at both ends.   The power converter according to any one of claims 1 to 6, wherein an impedance of the folded dipole antenna configured by the first conductor and the second conductor is inductive.   The power converter according to any one of claims 1 to 7, wherein the impedance of the folded dipole antenna and the impedance of the rectifier circuit are in a conjugate relationship.   The power converter according to any one of claims 1 to 8, wherein the impedance of the folded dipole antenna has a kink shape on a Smith chart.   When the thickness of the first element and the second element is t, and the element width of the first element and the second element is w, the thickness t and the element width w are (0.34 t) / ( The power conversion according to any one of claims 1 to 9, wherein 0.34t + 0.25w) <0.2 is satisfied, and the thickness t is at least twice the skin depth at the frequency of the radio wave. apparatus. A first conductor having a length corresponding to a half wavelength in a free space wavelength at a frequency of a received radio wave;
A first element extending from the first feeding point along the first conductor to the first end, and a second element along the first conductor from the second feeding point that forms a balanced terminal with the first feeding point. A second element extending to an end, and including the first conductor and a second conductor constituting a folded dipole antenna,
The width of the first conductor is wider than the width of the second conductor,
The length between the first end portion and the second end portion is a folded dipole antenna that is 0.6λe to 0.8λe, where λe is the electrical length of the wavelength at the frequency.

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