Multi-frequency shared antenna device

Abstract

The objective is to provide a multi-frequency shared antenna device that can be used for multiple frequencies and is easily made high-impedance. [Solution] The invention comprises a loop-shaped element and a linear element electromagnetically coupled to the loop-shaped element, wherein the linear element resonates at multiple frequencies.

Description

[Technical Field]

[0001] The present invention relates to an antenna device that can be used for multiple different frequencies. [Background technology]

[0002] Antennas are used in electronic devices that receive power via radio waves in various fields, such as power transmission systems using radio waves and sensors that utilize the power of weak radio waves. In recent years, various frequency bands have come to be used in this field depending on the application, so there is a demand for antennas that can be used across multiple frequency bands.

[0003] For example, Patent Document 1 describes 800MH Z and 1.9GH Z A multi-frequency antenna is described in which radiating plate elements are arranged parallel to the ground plate of a printed circuit board so that they can be used in the same frequency band, one ground point is provided on the radiating plate element, a feed point is provided on the other end, and a resonant circuit is connected between the ground point and the ground plate. This design results in a complex structure and makes it impossible to achieve high impedance. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2001-251128 [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a multi-frequency shared antenna device that can be used for multiple frequencies and is easily made high-impedance. [Means for solving the problem]

[0006] The multi-frequency shared antenna device according to the present invention comprises a loop-shaped element and a linear element electromagnetically coupled to the loop-shaped element, wherein the linear element resonates at multiple frequencies. Here, a linear element electromagnetically coupled to a loop-shaped element is one in which a power supply point is provided on the loop-shaped element, causing the linear element to be electromagnetically excited. Loop elements are elements with a rectangular or circular loop shape, while linear elements are elements with a straight or gently curved shape. This makes it possible to increase the impedance of the antenna.

[0007] Here, when we say that a linear element resonates at multiple frequencies, it may mean that it is composed of multiple resonant elements, each resonating at a different frequency. For example, a system can be constructed with multiple resonant elements of different lengths, where the relatively longer resonant elements resonate at relatively low frequencies, and the shorter resonant elements resonate at relatively high frequencies. The number of resonant elements can be matched to the number of shared frequency bands.

[0008] In the present invention, the linear element may resonate at multiple frequencies due to the loading of reactance. For example, by loading coils or capacitors at both ends of a linear element, the linear portion and the entire length can be used for multiple frequencies.

[0009] Furthermore, the linear element may resonate with the fundamental wave and its harmonics. [Effects of the Invention]

[0010] This invention can resonate in multiple frequency bands and, due to electromagnetic coupling, becomes a relatively high-impedance antenna, thus improving rectification efficiency when incorporated into rectenna devices or sensor power supplies. [Brief explanation of the drawing]

[0011] [Figure 1]An example of an antenna composed of a loop element and two linear elements is shown. (a) is one surface, and (b) is the other surface [Figure 2] An example in which reactance is loaded on a linear element is shown. [Figure 3] An example in which the thickness of a linear element is changed is shown. [Figure 4] (a) shows impedance characteristics, and (b) shows a Smith chart. [Figure 5] (a) shows VSWR characteristics, and (b) shows radiation efficiency.

Mode for Carrying Out the Invention

[0012] Examples of the antenna according to the present invention will be described below with reference to the drawings. FIG. 1 shows an example of two linear elements having different lengths. FIG. 1(a) shows one surface of a substrate, and (b) shows the other surface of the substrate. As shown in FIG. 1(a), a loop-shaped element 10 having feeding points F, F and a linear first resonant element 21 electromagnetically coupled to the loop-shaped element 10 are disposed on one surface of a substrate 1, and as shown in FIG. 1(b), a linear second resonant element 22 having a relatively short length is disposed on the other surface of the substrate so as to be electromagnetically coupled to the loop-shaped element 10. This is an example of such arrangement.

[0013] FIG. 2 shows an example in which coils 23b, 23b are loaded on both sides of a central linear portion 23a as a linear element 23. With this configuration, the entire length resonates at a low frequency, and resonance occurs at a high frequency between the reactance elements.

[0014] FIG. 3 shows an example in which the wire diameter of a central portion 24a is increased as a linear element 24. Accordingly, as a fundamental wave, for example, 2.4 GH Z resonates in the band, and 5.5 GH Z resonates at the second harmonic in the band.

[0015] A demonstration design was carried out for the example of the antenna device shown in FIG. 1 below, and this will be described. (1) Substrate ·NPC-F260A ·Size: 60 mm × 100 mm ·Thickness: 0.6 mm ·Relative permittivity: 2.56 ·Dielectric loss tangent: 0.0015 (2) Loop element (copper) ·Total loop length: half wavelength of 2.4 GHz Z ·Feed width: 2.8 mm (distance between F-F) ·Line width: 0.6 mm (3) First resonant element (copper) ·Total length: it is a half wavelength of 2.4 GHz, and the length is adjusted to achieve resonance. Z ·Line width: 1.0 mm ·Spacing from the loop element: 0.6 mm (arranged parallel to one side of the loop element) (4) Second resonant element (copper) ·Total length: it is a half wavelength of 5.5 GHz, and the length is adjusted to achieve resonance. Z ·Line width: 1.0 mm ·Arranged so as to cross the central portion of the loop element.

[0016] Next, the simulation results will be described. Fig. 4(a) shows the impedance characteristics, and Fig. 4(b) shows the Smith chart. At 2.4 GHz Z , a high impedance of 1.4 kΩ was exhibited, and at 5.5 GHz Z , a high impedance of 1.7 kΩ which is 1 kΩ or higher was exhibited. Fig. 5(a) shows the VSWR characteristics, and at 2.4 GHz Z a value of 1.4 was obtained, and at 5.5 GHz Z a value of 1.7 was obtained. Fig. 5(b) shows the radiation efficiency, and at 2.4 GHz Z it was 98%, and at 5.5 GHz Z it was 99%.

[0017] In the present demonstration design, the 2.4 GHz Z band and the 5.5 GHz Z ​​​While it was designed for use with two frequency bands, it is not limited to these frequencies and can also handle three or more frequency bands. [Explanation of Symbols]

[0018] 1 circuit board 10 Loop-shaped elements 21 First resonant element 22 Second resonance element

Claims

1. It comprises a loop-shaped element and a linear element electromagnetically coupled to the loop-shaped element, A multi-frequency shared antenna device characterized in that the linear element resonates at multiple frequencies.

2. The multi-frequency shared antenna device according to claim 1, characterized in that the linear element is composed of a plurality of resonant elements that resonate at a plurality of frequencies.

3. The multi-frequency shared antenna device according to claim 1, characterized in that the linear element resonates at multiple frequencies due to the loading of reactance.

4. A multi-frequency shared antenna device characterized in that the linear element resonates with the fundamental wave and its harmonics.

5. A multi-frequency shared antenna device according to any one of claims 1 to 4, characterized in that it is used as an antenna for a rectenna device.

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