JP7015054B2 - Power converter and folded dipole antenna - Google Patents

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, and the microwave is received by the balanced two-wire antenna. There is a balanced two-wire line type rectenna that outputs DC power to the DC output terminal based on waves.

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 one main surface of the substrate. It has a pair of parallel lines connected to the unit and extending in a direction orthogonal to the opposite direction of each of the antenna elements.

The rectifier circuit has a DC cutoff capacitor, a Schottky barrier diode arranged between the pair of lines, and the pair of lines separated from the Schottky barrier diode at a predetermined stage after the Schottky barrier diode. It has a smoothing capacitor arranged in.

The DC output terminal is connected to each of the pair of lines after the smoothing capacitor, and 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 having been set.

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

Japanese Unexamined Patent Publication No. 2007-116515

In the conventional balanced two-wire line type rectenna (power conversion device), an input filter (filter) is provided between the balanced two-wire type antenna (antenna) and the rectifier circuit. This is because the inductive component of the filter cancels out the capacitive component of the rectifier circuit to achieve impedance matching between the antenna and the rectifier circuit.

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

Therefore, it is an object of the present invention to provide a power conversion device having reduced loss and a folded dipole antenna.

The power conversion device according to the embodiment of the present invention has a first conductor having a length corresponding to a half wavelength in the free space wavelength at the frequency of the received radio wave, and a first conductor from the first feeding point along the first conductor. It has a first element extending to the end and a second element extending from the first feeding point and the second feeding point constituting the balanced terminal to the second end along the first conductor. The width of the first conductor includes the first conductor, the second conductor constituting the folded dipole antenna, the first feeding point, and the rectifying circuit connected to the second feeding point, and the width of the first conductor is the same as that of the second conductor. Wider than the width, the length between the first end and the second end is a length corresponding to 0.6λe to 0.8λe, where λe is the electrical length of the radio wave at the frequency. ..

It is possible to provide a power conversion device with reduced loss and a folded dipole antenna.

It is a figure which shows the power conversion apparatus 300 including the folded dipole antenna 100 of embodiment. It is a figure which shows the part of FIG. 1 enlarged. It is a figure which shows the simulation model of the folded dipole antenna 100. It is a Smith chart which shows the frequency characteristic of the impedance of the folded dipole antenna 100. It is a figure which shows the simulation model of the folded dipole antenna 100. It is a Smith chart which shows the frequency characteristic of the impedance of the rectifier circuit 200 seen from the folded dipole antenna 100 side. It is a Smith chart which shows the frequency characteristic of the impedance of the folded dipole antenna 100. It is a figure which shows the folding dipole antenna 100M of the modification of embodiment. It is a Smith chart which shows the frequency characteristic of the impedance of the folded dipole antenna 100M. It is a figure which shows the Smith chart obtained by the simulation model with different length Lf. It is a figure which shows the Smith chart obtained by the simulation model with different length Lf. It is a Smith chart which shows the impedance of a folded dipole antenna 100. It is a Smith chart which shows the impedance of a folded dipole antenna 100. It is a Smith chart which shows the impedance of a folded dipole antenna 100. It is a Smith chart which shows the impedance of a folded dipole antenna 100. It is a figure which shows the simulation model of the folded dipole antenna 100. It is a figure which shows the simulation model of the folded dipole antenna 100. It is a Smith chart which shows the frequency characteristic of the impedance of the folded dipole antenna 100. It is a Smith chart which shows the frequency characteristic of the impedance of the folded dipole antenna 100. It is a figure which shows the cross section of the element 110 and 120. It is a figure explaining the equivalent radius of elements 110 and 120.

Hereinafter, an embodiment to which the power conversion device of the present invention and the folded dipole antenna are applied will be described.

<Embodiment>
FIG. 1 is a diagram showing a power conversion device 300 including a folded dipole antenna 100 of the embodiment. In the following, it will be described using the XYZ coordinate system.

The power conversion device 300 includes a folded dipole antenna 100 and a rectifier circuit 200. The power conversion device 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 the radio wave is 540 MHz will be described.

The folded dipole antenna 100 has an inductive impedance characteristic. Therefore, the power conversion device 300 can achieve impedance matching between the rectifier circuit 200 showing the 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. can. The details will be described below.

The folded dipole antenna 100 has a substrate 101 and elements 110 and 120. The substrate 101 is a substrate having a low dielectric loss, such as a Teflon (registered trademark) substrate or a PPE (Polyphenylene Ether) substrate. Further, the substrate 101 is not limited to the Teflon substrate or the PPE substrate, and may be, for example, a FR-4 (Flame Retardant type 4) standard wiring board, 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 ends 111 and 112 and is provided on the surface of the substrate 101. The element 110 is an example of the first conductor. The element 110 extends along the X-axis with the ends 111 and 112 at both ends. The element 110 is arranged in parallel with the element 120.

The length of the element 110 (the length between the ends 111 and 112) corresponds to about half the wavelength (about λ _0/2 ) of the free space wavelength λ ₀ of the radio wave received by the folded dipole antenna 100. Is set to. This is because the element 110 is a portion corresponding to the total length (length from end to end in the X-axis direction) of the folded dipole antenna 100.

Here, the length corresponding to the half wavelength (λ _0/2 ) of the free space wavelength λ ₀ of the radio wave is not strictly limited to the half wavelength (λ _0/2 ) of the free space wavelength λ ₀ of the radio wave, and is folded back. In the adjustment for functioning as the dipole antenna 100, it is meant to include the length when the wavelength is slightly shorter than the half wavelength (λ _0/2 ). Here, the length of the element 110 is, for example, 244 mm corresponding to 0.44λ ₀ at 540 MHz as a length corresponding to a half wavelength (λ _0/2 ).

Further, the element width (width in the Y-axis direction) of the element 110 is made thicker 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 has elements 120A and 120B and is provided on the surface of the substrate 101. The element 120 is an example of the second conductor.

The element 120A has a feeding point 121A and an end 122A. The element 120A is an example of the first element. The feeding point 121A is an example of the first feeding point. The end portion 122A is an example of the first end portion. 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 121A is connected to the terminal 201 of the rectifier circuit 200.

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

Here, the electric length λe is the wavelength of an electromagnetic wave transmitted in a transmission medium such as the element 120A provided on the substrate 101, and the shortening rate varies depending on the relative permittivity of the substrate 101 and the like. Due to this shortening rate, the length (0.3λe to 0.4λe) of the electric wave length λe is shortened by 0.3 to 0.4 times.

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

The feeding points 121A and 121B are examples of balanced terminals. Terminals 201 and 202 of the rectifier circuit 200 are connected to the feeding points 121A and 121B. 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, for example. In FIG. 1, the connection portion between the feeding points 121A and 121B and the terminals 201 and 202 of the rectifier circuit 200 is shown 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 axisymmetric with the element 120A with an axis extending in the Y-axis direction passing through the center of the element 110 in the X-axis direction as an axis of symmetry in a plan view.

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 portion 122B and the intermediate point between the feeding points 121A and 121B is set to a length of 0.3 to 0.4 times the electric length λe (0.3λe to 0.4λe). Has been done.

Therefore, the length from the end portion 122A to the end portion 122B of the element 120 is 0.6 to 0.8 times the electric length λe (0.6λe to 0.8λe). 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 with the inductive impedance of the folded dipole antenna 100.

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

The rectifier circuit 200 includes terminals 201, 202, capacitors 211, 212, 213, 214, diodes 221, 222, 223, 224, and output terminals 231 and 232. The rectifier circuit 200 is, for example, a Cockcroft-Walton type 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. Further, as shown in FIG. 1, the diodes 221, 222, 223, and 224 are connected in a cross-shaped manner between the capacitors 211, 212, 213, and 214.

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

Here, with reference to FIG. 2, the names of the dimensions of each part used in the following description will be described. FIG. 2 is an enlarged view showing a part of FIG. 1. In the following description, in addition to the lengths La and Lb described above, the widths Wa and Wb and the interval d are used.

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

FIG. 3 is a diagram showing 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 length La is set to 0.1λe, 0.2λe, 0.3λe, 0.4λe, 0.5λe, and 0.6λe, respectively. Has been done. 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 element 110 is in the X-axis direction. The length Lb is 244 mm. 244 mm is 0.44 times as long as 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 (center point of the Smith chart) is 2 kΩ. This is the same for the other Smith charts shown below.

In FIGS. 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 radio wave frequency is 400 MHz. The Smith chart when changed from to 700MHz is shown.

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

When the length La shown in FIG. 4B is 0.2λe, a locus of the equal resistance circle passing through the short-circuit point moving from about -166 degrees to about 173 degrees was obtained as the frequency increased. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the length La shown in FIG. 4C is 0.3λe, a locus of the equal resistance circle passing through the short-circuit point moving from about 180 degrees to about 140 degrees was obtained as the frequency increased. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the length La shown in FIG. 4D is 0.4λe, an arc is drawn from about 165 degrees to about 180 degrees slightly inside the equal resistance circle passing through the short-circuit point as the frequency increases. , A locus was obtained that moved from about 180 degrees to about 35 degrees.

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

When the length La shown in FIG. 4 (F) is 0.6λe, the locus shown in FIG. 4 (E) is further contracted inward to obtain a locus that makes one rotation.

From the above results, when the lengths La shown in FIGS. 4 (C) and 4 (D) are 0.3λe and 0.4λe, they rotate clockwise in the upper half region of the Smith chart circle and are inductive. A locus representing the above was obtained. From this, it was found that the length La is in an appropriate range of 0.3λe to 0.4λe 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. 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 length La is 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 element 110 is in the X-axis direction. The length Lb is 244 mm. 244 mm is 0.44 times as long as 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 seen from the folded dipole antenna 100 side. FIG. 6 shows a Smith chart when the frequency of radio waves 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 was confirmed that the impedance exhibits capacitive impedance.

Here, the rectification efficiency in the rectifier circuit 200 is improved by realizing the folded dipole antenna 100 having an inductive impedance coupled with the rectifier circuit 200 having a capacitive impedance showing the frequency characteristics as shown in FIG. Increase. 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 having 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. In FIGS. 7A to 7E, the length La is set to 0.32λe, 0.34λe, 0.35λe, 0.36λe, and 0.38λe, respectively, and the frequency of the radio wave is changed from 400 MHz to 700 MHz. The Smith chart when it is made to do is shown. Further, FIG. 7F shows a Smith chart of the simulation model 100D1 (see FIG. 3D) having a length La of 0.4λe. This is the same as that shown in FIG. 4 (D).

When the length La shown in FIG. 7 (A) is 0.32λe, the equivalence circle passing through the short-circuit point is slightly inward from about 180 degrees to about 170 degrees from the vicinity of the short-circuit point as the frequency increases. After entering, it moved up to about 120 degrees along an equal resistance circle through the short circuit point. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the length La shown in FIG. 7B is 0.34λe, the short-circuit point is formed after forming a kink vertex at about 170 degrees from the point near the short-circuit point at about 175 degrees as the frequency increases. A locus was obtained that moved from about 165 degrees to about 100 degrees along an equal resistance circle passing through. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the length La shown in FIG. 7 (C) is 0.35λe, the short-circuit point is formed after forming a kink vertex at about 170 degrees from the point near the short-circuit point at about 175 degrees as the frequency increases. A locus was obtained that moved from about 160 degrees to about 95 degrees along an equal resistance circle passing through. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle. The kink vertices were larger than when the length La was 0.34λe.

When the length La shown in FIG. 7 (D) is 0.36λe, the short-circuit point is formed after forming a kink vertex at about 170 degrees from the point near the short-circuit point at about 175 degrees as the frequency increases. A locus was obtained that moved from about 160 degrees to about 85 degrees along an equal resistance circle passing through. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle. The kink vertices were larger than those when the lengths La were 0.34λe and 0.35λe.

When the length La shown in FIG. 7 (E) is 0.38λe, a kink vertex is formed from a point of about 170 degrees with an increase in frequency, and then about along an equal resistance circle passing through a short-circuit point. A locus was obtained that moved from 160 degrees to about 65 degrees. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the length La shown in FIG. 7 (F) is 0.40λe, the locus of the kink drawn first is further expanded as compared with the locus of the length La shown in FIG. 7 (E) of 0.38λe, and the frequency is increased. With the increase, a locus was obtained from a point of about 165 degrees, after forming a kink apex, moving from about 160 degrees to about 35 degrees along an equal resistance circle passing through the short circuit point. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

From the above results, all the loci in FIGS. 7A to 7F are loci that rotate clockwise in the upper half of the circle of the Smith chart, have kink vertices, and show inductiveness. .. For example, considering the use for communication with a wide frequency band, an impedance characteristic having a kink vertex in the upper half region of the Smith chart circle is effective. However, from the viewpoint that conjugate matching can be obtained in a wide band with the capacitive impedance of the rectifier circuit 200 showing the frequency characteristics as shown in FIG. 6, among these, FIGS. 7 (B), (C), and (D) are shown. It was found that the case where the indicated length La was 0.34λe to 0.36λe was particularly good.

From the above, it was found that the length La of 0.34λe to 0.36λe is particularly good in the range of the length La of 0.32λe to 0.4λe.

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

Since the power conversion device 300 does not include a low-pass filter between the folded dipole antenna 100 and the rectifier circuit 200, the 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.

Although the rectifier circuit 200 has been described above as a Cockcroft-Walton type rectifier circuit, the rectifier circuit 200 is not limited to the Cockcroft-Walton type. Any type of rectifier circuit can be used as long as it can rectify the high frequency power output from the folded dipole antenna 100 to DC power.

Further, in the above, as an example, the mode in which the folded dipole antenna 100 receives a radio wave of 540 MHz has been described, but the frequency is not limited to 540 MHz, and the inductive impedance of the folded dipole antenna 100 is adjusted according to a desired frequency. do it. Such adjustments can be made mainly by setting the lengths and spacings of the elements 110 and 120 at the design stage.

FIG. 8 is a diagram showing a folded dipole antenna 100M of a modified example of the embodiment. The folded dipole antenna 100M has a substrate 101M and elements 110 and 120M. Here, the same components as those of the folded dipole antenna 100 shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

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

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

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

The terminals 123A1 and 123B1 are located on the negative side of the Y-axis of the substrate 101M and in front of the long side extending in the X-axis direction. As an example, the length La is 0.35λe, and the lengths of the extension portions 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 the impedance when the frequency of the radio wave received by the folded dipole antenna 100M is changed from 400 MHz to 700 MHz. Further, 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. 7 (C).

The locus of the folded dipole antenna 100M shown in FIG. 9A passes through the short-circuit point after forming a kink apex at about 165 degrees from a point of about 170 degrees near the short-circuit point as the frequency increases. A locus was obtained that moved from about 160 degrees to about -110 degrees along the resistance circle. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle. The kink vertices were slightly shifted upward from the locus of the simulation model 100C2 shown in FIG. 9B, and a large kink vertex was obtained. This indicates that the kink vertices of the folded dipole antenna 100M are more inductive than the kink vertices of the simulation model 100C2. The trajectory of the simulation model 100C2 shown in FIG. 9B has better conjugate matching with the input impedance of the rectifying 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.

10 and 11 are Smith charts showing the frequency characteristics of impedance when the frequency of radio waves is changed from 400 MHz to 700 MHz in a simulation model of a folded dipole antenna 100M having different lengths Lf of the extension portions 123A and 123B. 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 permittivity 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 are in the Y-axis direction. The interval 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 as long as the free space wavelength λ ₀ of the radio wave of 540 MHz. The electric length λe and the free space wavelength λ ₀ are values at 540 MHz.

Further, FIG. 10A shows the frequency characteristics (same as FIG. 7C) of the impedance of the simulation model 100C2 (see FIG. 5C) having no extension portions 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, a short-circuit point is formed after forming a kink vertex at about 168 degrees from a point near the short-circuit point at about 170 degrees as the frequency increases. A locus was obtained that moved from about 160 degrees to about -40 degrees along an equal resistance circle passing through. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle. The kink apex was larger than the case where the length Lf was 0 mm.

When the lengths Lf shown in FIGS. 10 (C) to 10 (F) are λe / 40, λe / 30, λe / 20, and λe / 18, the degree is about 170 degrees near the short-circuit point as the frequency increases. After forming the kink apex at about 165 degrees from the point, it moves from about 160 degrees to about -70 degrees, about -105 degrees, about -138 degrees, about -145 degrees along the equi-resistance circle passing through the short circuit point. A trajectory was obtained. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle. The kink vertices gradually moved above the horizontal axis along the equi-resistance circle as the length Lf became longer, and tended to become more inductive.

When the lengths Lf shown in FIGS. 11A to 11C are λe / 16, λe / 14, and λe / 12, the point of about 165 degrees near the short-circuit point becomes about as the frequency increases. After forming the kink apex at 165 degrees, a locus was obtained that moved from about 160 degrees to about -150 degrees, about -155 degrees, and about -165 degrees along the equi-resistance circle passing through the short-circuit point. As the frequency increased, the arcuate locus after drawing the kink vertices tended to become smaller.

When the lengths Lf shown in FIGS. 11 (D) to 11 (F) are λe / 10, λe / 8, and λe / 6, the laterality is increased from a point of about 160 degrees near the short-circuit point as the frequency increases. Kink vertices were obtained near the axis, but no clearly inductive locus was obtained.

From the above, it was found that when the extension portions 123A and 123B are attached, the length Lf is preferably λe / 20 or less.

12 to 15 are Smith charts showing the frequency characteristics of the impedance when the frequency of the radio wave received by the folded dipole antenna 100 is changed. 12 to 15 show the frequency characteristics of the impedance 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. Smith chart.

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 length La is 0.35λe, and the Lb is 244 mm (0.44λ ₀ ). Since λe / 100 is 5.56 mm and λe / 200 is 2.78 mm, it is about λe / 139 that the interval d is 4 mm.

When the intervals d shown in FIGS. 12 (A) to 12 (C) are λe / 10, λe / 20, and λe / 30, as the frequency increases, the resistance circle from about 175 degrees passes through the short-circuit point. Trajectories were obtained that moved to about -50 degrees, about -25 degrees, and about 0 degrees. When the frequency increased from 400 MHz, it was a locus that showed inductiveness and entered inward, but no kink apex was obtained.

When the intervals d shown in FIGS. 12 (D) to 12 (F) are λe / 40, λe / 50, and λe / 60, the distance increases from about 175 degrees near the short-circuit point to about 165 as the frequency increases. After forming the kink vertices at degrees, trajectories were obtained that traveled from about 160 degrees to about 20 degrees, about 35 degrees, and about 45 degrees along an equal resistance circle through the short circuit point. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the intervals d shown in FIGS. 13 (A) to 13 (F) are λe / 70, λe / 80, λe / 90, λe / 100, λe / 200, and λe / 300, a short circuit point occurs as the frequency increases. After forming a kink apex at about 165 degrees from a point near about 175 degrees, about 160 degrees to about 55 degrees, about 60 degrees, about 67 degrees, about 72 degrees along an equal resistance circle passing through the short circuit point. , A locus moving to about 95 degrees and about 104 degrees was obtained. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the intervals d shown in FIGS. 14A to 14F are λe / 400, λe / 500, λe / 600, λe / 700, λe / 800, and λe / 900, a short circuit point is formed as the frequency increases. After forming a kink apex from a point near 175 degrees, up to about 110 degrees, about 113 degrees, about 115 degrees, about 118 degrees, about 118 degrees, about 123 degrees along an equal resistance circle through the short circuit point. A moving trajectory was obtained. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

When the intervals d shown in FIGS. 15A to 15F are λe / 1000, λe / 2000, λe / 3000, λe / 4000, λe / 5000, and λe / 6000, a short circuit point is formed as the frequency increases. After forming a kink apex from a point near 175 degrees, up to about 125 degrees, about 135 degrees, about 142 degrees, about 128 degrees, about 150 degrees, about 152 degrees along an equal resistance circle through the short circuit point. A moving trajectory was obtained. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

From the above, it can be seen that when the interval d is λe / 40 or less, the kink vertices are obtained and the inductive locus is obtained. Further, it can be seen that it is particularly good because the kink vertices are obtained and the inductive locus is clearly obtained when the interval d is from λe / 40 to around λe / 1000. Further, λe / 1000 is 0.56 mm, and λe / 6000 is 0.09 mm.

The interval d may be λe / 1000, but for example, when the elements 110 and 120 are manufactured by an etching process, the interval 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. In FIG. 16, the reference numerals of the respective parts are omitted.

In the 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 portion is 6 mm in the X-axis direction and 4 mm in the Y-axis direction, and the number of cycles of the meander portion is 10 for both the elements 120A and 120B.

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

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

The meander portion 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 cycles of the meander portion is 10, 11, 12, 13, 14 for the elements 120A and 120B, respectively. , 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 element 110 is in the X-axis direction. The length Lb is 244 mm (0.44λ ₀ ).

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

In the Smith chart of the simulation model 100A3 shown in FIG. 18A, as the frequency increases, from the vicinity of the short-circuit point, from about 180 degrees of the equi-resistance circle passing through the short-circuit point, along the equi-resistance circle passing through the short-circuit point. A trajectory of movement up to about 30 degrees was obtained. It is a locus showing inductiveness as the frequency increases, but it has no kink apex.

In the Smith charts of the simulation models 100B3 and 100C3 shown in FIGS. 18B and 18C, a kink vertex is formed slightly inward from about 180 degrees of the equal resistance circle passing through the short-circuit point as the frequency increases. A locus was obtained that moved to about 106 degrees at about 116 degrees along the equi-resistance circle passing through the short-circuit point.

In the Smith charts of the simulation models 100D3, 100E3, and 100F3 shown in FIGS. 18 (D), (E), and (F), kink vertices were formed from a point of about 175 degrees near the short-circuit point as the frequency increased. Later, a locus was obtained that traveled from about 160 degrees to about 95 degrees, about 80 degrees, and about 65 degrees along an equal resistance circle passing through the short circuit point. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

In the Smith charts of the simulation models 100A4 and 100B4 shown in FIGS. 19A and 19B, as the frequency increases, a kink vertex is formed from a point of about 170 degrees near the short-circuit point and then passes through the short-circuit point. Trajectories were obtained that moved along the equal resistance circle to about 45 degrees and about 25 degrees. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

In the Smith charts of the simulation models 100C4, 100D4, 100E4, and 100F4 shown in FIGS. 19 (C), (D), (E), and (F), as the frequency increases, near the short-circuit point at about 175 degrees. Trajectories were obtained that formed the kink vertices and moved along the equi-resistance circle through the short-circuit point to about 0 degrees, about -30 degrees, about -55 degrees, and about -80 degrees. As the frequency increased, the locus gradually passed through the short-circuit point and entered the inside of the equal resistance circle.

From the above, the simulation models 100D3, 100E3, 100F3 shown in FIGS. 18D to 18F and the simulation models 100A4, 100B4 shown in FIGS. 19A, 19B have kink vertices at desired frequencies. However, it was found to show an inducible 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 set to about 0. It was found that it is better to set it to 42λe to 0.52λe. Further, by providing the meander portion, the length of the substrate required to obtain the same effect in the X direction can be shortened, so that the dimensions of the folded dipole antenna and the power conversion device using the folded dipole antenna can be reduced in the X direction. can.

Next, the skin effect and the equivalent radius in the elements 110 and 120 will be described with reference to FIGS. 20 and 21.

FIG. 20 is a diagram showing a cross section of the elements 110 and 120. 20 (A) and 20 (B) show cross sections of elements 110 and 120 obtained along the Y axis. 20 (A) and 20 (B) show a substrate 101 on which the folded dipole antenna 100 is mounted. Further, in FIGS. 20A and 20B, the portion where the high frequency current flows through the elements 110 and 120 is shown in gray. As an example, a current of 540 MHz flows through the part shown in gray 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. 20 (A) is 18 μm, the element width w1 is 0.1 mm to 0.5 mm, the thickness of the element 110 is 18 μm for t1 and the element width w2 is 2 mm to 8 mm. be. Further, the thickness t2 of the element 120 shown in FIG. 20B is twice the skin depth, the element width w1 is 0.1 mm to 0.5 mm, and the thickness of the element 110 is t2 twice the skin depth. The element width w2 is 2 mm to 8 mm. Further, 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 the frequency is 2.4 GHz, the skin depth is 1 μm.

The elements 110 and 120 are manufactured 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, but the side surfaces of the elements 110 and 120 are scraped by the etching process, so that the smoothness is lower than that of the upper surface, and the surface surface is smooth. Is rough. Therefore, the side surfaces of the elements 110 and 120 have higher high frequency resistance than the upper surface, so that the loss increases.

As shown in FIG. 20 (A), when the elements 110 and 120 are made thicker, the ratio of the current flowing on the side surfaces of the elements 110 and 120 is higher than when the elements 110 and 120 are made thinner as shown in FIG. 20 (B). Will increase. This tendency is particularly remarkable in the element 120 having a narrow element width.

FIG. 21 is a diagram illustrating 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. 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 the equations (1) and (2), respectively, and the impedance step-up ratio (n ² ) can be expressed by the equation (3).

In order to reduce the current flowing on the side surface of the element 120 and reduce the loss, it is desirable that the current flowing on the side surface is less than 20% of the total. When the ratio of the equivalent radius r1 of the element 120 obtained by the equation (1) to the current flowing on 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, since the elements 120 and 120 have the same size and are arranged line-symmetrically in a plan view, the equivalent radii of the elements 120 are equivalent to the elements 120. Equal to the radius.

Although the power conversion device and the folded dipole antenna according to the exemplary embodiment of the present invention have been described above, the present invention is not limited to the specifically disclosed embodiments and is claimed for a patent. Various modifications and changes are possible without departing from the range.

100, 100M folded dipole antenna 101, 101M board 110, 120, 120A, 120B, 120M, 120MA, 120MB element 111, 112 end 121A, 121B feeding 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 the free space wavelength at the frequency of the received radio wave, and
The first element extending from the first feeding point to the first end along the first conductor, and the second feeding point forming the equilibrium terminal with the first feeding point to the second along the first conductor. A second conductor having a second element extending to the end, the first conductor, and a second conductor constituting a folded dipole antenna,
Including the first feeding point and the rectifier circuit connected to the second feeding point.
The width of the first conductor is wider than the width of the second conductor.
A power conversion device having a length between the first end portion and the second end portion of 0.6λe to 0.8λe, where λe is the electrical length of the wavelength at the frequency. The power conversion device according to claim 1, wherein the distance between the first conductor and the second conductor is 1/40 or less of the electric length λe of the wavelength. The first or second aspect of the present invention further includes a first extension line and a second extension line connected to the first feeding point and the second feeding point, respectively, and extending in a direction away from the second conductor in a plan view. Power converter. The power conversion device according to claim 3, wherein the length of the first extension line and the second extension line is 1/20 or less of the electric length λe of the wavelength. The power conversion device according to any one of claims 1 to 4, wherein the second conductor has a meander portion. The power conversion device according to any one of claims 1 to 4, wherein the second conductor has meander portions at both ends. The power conversion device according to any one of claims 1 to 6, wherein the impedance of the folded dipole antenna composed of the first conductor and the second conductor is inductive. The power conversion device 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 conversion device according to any one of claims 1 to 8, wherein the impedance of the folded dipole antenna has a Kink shape in a Smith chart. Assuming that the thickness of the first element and the second element is t and the element widths of the first element and the second element are 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. Device. A first conductor having a length corresponding to a half wavelength in the free space wavelength at the frequency of the received radio wave, and
The first element extending from the first feeding point to the first end along the first conductor, and the second feeding point forming the equilibrium terminal with the first feeding point to the second along the first conductor. It has a second element extending to the end, 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 folded dipole antenna has a length between the first end portion and the second end portion of 0.6λe to 0.8λe, where λe is the electrical length of the wavelength at the frequency.

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