Circular polarization compatible rectenna device

Abstract

The aim is to provide a rectenna device that can receive power in a circularly polarized manner and has high overall power reception efficiency. [Solution] The radiating element layer is arranged on the upper surface of the ground conductor via a dielectric layer, and the radiating element layer has two mutually orthogonal centerlines, with a predetermined distance D from the ends of the radiating element layer, and a rectifier element A is provided between the rectifier element A and the ground conductor, and a rectifier element B is provided between the rectifier element B and the ground conductor, and the rectifier element A and the rectifier element B are connected in parallel to the output terminal.

Description

Technical Field

[0001] The present invention relates to a rectenna device used for wireless power transmission, and particularly to a circularly polarized power receiving rectenna device capable of making a power receiving antenna compatible with circular polarization.

Background Art

[0002] A rectenna device is a device that combines an antenna function and a rectifying function. For example, considering wireless power supply to a moving body such as a drone as shown in FIG. 8, as the moving body flies, problems regarding the directivity of the power receiving antenna due to its azimuth angle and the like occur. Therefore, a rectenna with high power receiving efficiency was studied while making the power receiving antenna a circularly polarized antenna. As a rectenna with high power receiving efficiency, as shown in Document 1, there is a configuration in which the radiation element of the antenna and the rectifying diode are directly connected. Since no circuit is provided between the rectifying diode and the antenna, high rectification efficiency can be obtained. At this time, the admittance of the antenna is designed to be conjugate matched to the rectifying diode. Therefore, the admittance of the antenna becomes low conductance and inductive susceptance. As an antenna for a rectenna having such admittance, for example, Document 2 discloses a patch antenna for a rectenna, the admittance of which is low conductance and inductive susceptance, but the radiation element is rectangular and cannot correspond to a circularly polarized rectenna.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

[0004] The present invention aims to provide a rectenna device that is capable of receiving power in a circularly polarized manner and has high overall power reception efficiency. [Means for solving the problem]

[0005] The rectenna device according to the present invention has a radiating element layer arranged on the upper surface of a ground conductor via a dielectric layer, the radiating element layer has two mutually orthogonal centerlines and a feed point A and a feed point B formed at a predetermined distance D from the end of the radiating element layer, a rectifier element A is provided between the feed point A and the ground conductor, a rectifier element B is provided between the feed point B and the ground conductor, and the rectifier element A and the rectifier element B are connected in parallel to the output terminal.

[0006] The present invention is characterized by forming two feed points A and B in a direction orthogonal to the radiating element which is a planar antenna, and by combining these with two rectifying elements A and B to form a rectenna.

[0007] There are various ways to implement these elements. For example, the radiating element layer has openings A and B formed near the feed points A and B, respectively, and rectifier elements A and B are formed in the openings A and B, respectively, and the RF of rectifier element A A The input terminal and the power supply point A are electrically connected, and the rectifier element A is connected to the ground conductor, and the RF of the rectifier element B B An example is one in which the input terminal and the power supply point B are electrically connected, and the rectifier element B is electrically connected to the ground conductor. In this case, it is best to provide symmetrical apertures so that the RF current distribution in the radiating element layer is symmetrical.

[0008] Furthermore, here, the output terminal DC of the rectifier element A A and the output terminal DC of the rectifier element B B By having the output power generated on the back side of the dielectric layer through through-holes A and B provided in the dielectric layer, interference between the output wiring from the rectifier element and the radiated power from the radiating element layer can be suppressed.

[0009] In this invention, slots can be made in the ground conductor to electromagnetically couple the radiating element layer and the rectifying element. For example, slots A and B of approximately π / 2 wavelength are formed in the ground conductor, corresponding to the positions of the feed points A and B of the radiating element layer, and rectifier elements A and B are provided on the lower surface of the ground conductor, and the RF of rectifier elements A and B A Input terminal and RF B The input terminals may be arranged so as to straddle the central parts of slots A and B, respectively. Further, a second dielectric layer is provided on the lower surface of the ground conductor, slots A1 and B1 approximately λ / 2 in length are formed in the ground conductor corresponding to directly below the power feeding points A and B of the radiation element layer, the rectifying elements A and B are disposed on the lower surface of the second dielectric layer, and open stubs approximately λ / 4 in length disposed so as to straddle the slots A1 and B1 are connected to the rectifying elements A and B. The rectifying elements A and B may be electrically connected to the ground conductor.

Advantages of the Invention

[0010] In the rectenna device according to the present invention, a rectifying element is directly connected to a radiation element, and a patch antenna having an admittance characteristic of low conductance and inductive susceptance is provided, which can serve as a rectenna capable of corresponding to a circularly polarized transmission wave.

Brief Description of the Drawings

[0011] [Figure 1] A configuration example of a patch antenna according to the present invention is shown. [Figure 2] A configuration example of a rectifying element used in the present invention is shown. [Figure 3] A chart of the antenna admittance Yrec is shown. [Figure 4] An example in which an opening is provided in a radiation element layer and a rectifying element is mounted is shown. (a) is an overall view, and (b) is a partially enlarged view of the opening. [Figure 5] An example of wiring of a rectifying element is shown. [Figure 6] An example in which a rectifying element is mounted with a slot provided is shown. [Figure 7] An example in which a multilayer substrate is used is shown. [Figure 8] An example of use of a rectenna is shown.

Embodiments for Carrying Out the Invention

[0012] First, a basic configuration example of a rectenna according to the present invention will be described using FIGS. 1 to 3. FIG. 1 shows a configuration example of a patch antenna. <> It has a radiation element layer 13 on the upper surface of a ground conductor 11 via a dielectric layer 12. The radiation element layer 13 is vertically symmetric with respect to the center line in the X-axis direction and horizontally symmetric with respect to the center line in the Y-axis direction in a plan view. Although the radiation element layer in FIG. 1 is square, it may be circular. This is an example in which a feeding point A is formed on the center line in the X-axis direction of the radiation element layer 13 and a feeding point B is formed on the center line in the Y-axis direction. Here, let the width of the radiation element layer formed of a square be W, and the distance from the ends of the radiation element layer 13 to the feeding points A and B be D. FIG. 2 shows a configuration example of a pair of rectifying elements A and B. A rectifying element A is formed between the feeding point A and the ground conductor 11, a rectifying element B is formed between the feeding point B and the ground conductor 11, and their two output terminals are connected in parallel. If the admittance of the rectifying element is Yrec and the admittance of the antenna is Yant, they are designed to be conjugate.

[0013] The admittance chart in the case of the above configuration is shown in FIG. 3. It was obtained in the 5.8 GHz band using a ground conductor 11 with a thickness of 18 μm, a dielectric layer with a thickness of 0.96 mm, a relative dielectric constant of 2.58, and a dielectric loss tangent of 0.0014. Charts are shown for cases where the ratio of the width W to the distance D of the radiation element layer 13 is (a) D / W = 0.1, (b) D / W = 0.2, (c) D / W = 0.3, and (d) D / W = 0.4, respectively. From this, it can be seen that by changing the values of W and D / W, any Yant can be obtained. Therefore, if the admittance Yrec of the rectifying element and the admittance Yrec of the antenna are designed to be conjugate, good rectification efficiency can be obtained as a rectenna.

[0014] Next, a specific implementation example will be described. FIG. 4 shows Example 1. This example is one in which openings 13A and 13B are provided in the radiation element layer 13 as shown in FIG. 4(a), and rectifying elements A and B are mounted in these openings 13A and 13B as shown in FIG. 4(b). Note that Figure 4(b) uses rectifier element A as an example, and the same applies to rectifier element B. In this embodiment, openings 13A and 13B are provided outside the respective feed points A and B, and opening 13a is provided symmetrically to opening 13A, and opening 13b is provided symmetrically to opening 13B, so that the RF current distribution on the radiating element layer is symmetrical. In this case, the RF input terminals of rectifier elements A and B are connected to the feed points A and B, and rectifier elements A and B are electrically connected to the ground conductor 11 via through-holes 14A and 14B.

[0015] Figure 5 shows Example 2. This is an example in which the DC outputs from rectifier elements A and B are routed to the back side of the substrate via through-holes 15A and 15B provided in the dielectric layer 12, as opposed to Example 1. This method suppresses interference between the rectifier elements A and B and the radiating element layer due to the output wiring.

[0016] Figure 6 shows Example 3. This embodiment shows an example in which slots of approximately π / 2 wavelength are formed in the ground conductor 11 so that rectifier elements A and B can be provided on the back side of the substrate, and electromagnetic coupling is performed. In this case, the rectifier element is placed in the center of the slot in the longitudinal direction, and the wiring is connected so as to span across the slot.

[0017] Figure 7 shows Example 4. This embodiment, like Embodiment 3, is an example of electromagnetic coupling via slots. However, a multilayer substrate is used in which a second dielectric layer 11a is laminated on the lower surface (back surface) of the ground conductor 11. Open stubs 17A and 17B of approximately π / 4 wavelength are placed on the back surface of the second dielectric layer 11a, straddling slots 16A and 16B, and are electromagnetically coupled and connected to rectifier elements A and B. Furthermore, rectifier elements A and B are electrically connected to the ground conductor 11 via through-holes. [Explanation of symbols]

[0018] 11. Ground conductor 12 Dielectric layer 13. Radiation element layer

Claims

1. The ground conductor has a radiating element layer arranged on its upper surface via a dielectric layer, The radiating element layer has two mutually orthogonal centerlines, and has power supply points A and B formed at a predetermined distance D from the ends of the radiating element layer. A rectifier element A is provided between the power supply point A and the ground conductor. A rectifier element B is provided between the power supply point B and the ground conductor. A rectenna device characterized by having the rectifier element A and rectifier element B connected in parallel to the output terminal.

2. The radiating element layer has openings A and B formed near the feed points A and B, respectively, and rectifier elements A and B are formed in the openings A and B, respectively. RF of the rectifier element A Ａ The input terminal and the power supply point A are electrically connected, and the rectifier element A is connected to the ground conductor. RF of the rectifier element B Ｂ The rectenna device according to claim 1, characterized in that the input terminal and the power supply point B are electrically connected, and the rectifier element B is electrically connected to the ground conductor.

3. Output terminal DC of rectifier element A Ａ and the output terminal DC of the rectifier element B Ｂ The rectenna device according to claim 2, characterized in that the output is generated on the back side of the dielectric layer through through-holes A and B provided in the dielectric layer.

4. Slots A and B, each approximately π / 2 wavelength in size, are formed in the ground conductor, corresponding to the positions of the feed points A and B of the radiating element layer. Rectifier elements A and B are provided on the lower surface of the ground conductor, and the RF of rectifier elements A and B Ａ Input terminal and RF Ｂ The rectenna device according to claim 1, characterized in that the input terminals are arranged so as to straddle the central portions of the slots A and B, respectively.

5. The second dielectric layer is provided on the lower surface of the ground conductor, and slots A １ , B １ approximately π / 2 wavelengths long are formed in the ground conductor corresponding to directly below the power supply points A and B of the radiation element layer, and the rectifying elements A and B are arranged on the lower surface of the second dielectric layer. At the same time, open stubs approximately π / 4 wavelengths long arranged so as to straddle the slots A １ , B １ are connected to the rectifying elements A and B, and the rectifying elements A and B are electrically connected to the ground conductor. The rectenna device according to claim 1, characterized in that

Images