JP2002299880A - Electromagnetic wave shielding antenna element and electromagnetic wave shield using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave shielding antenna element, and an electromagnetic wave shield which is capable of reliably shielding electromagnetic waves. SOLUTION: A pair of front and back side electromagnetic wave shielding antenna elements FA1-FAn, RA1-RAn are disposed in an window glass 1. These elements are combinations of microdipole antenna elements MD and microloop elements ML for generating a circular polarization. Currents flowing on the pair of front and back side antenna elements take opposite phase, and one antenna element detects electromagnetic waves to be shielded while the other element radiates electromagnetic waves corresponding to the detected electromagnetic waves to be shielded, thereby canceling resultant electromagnetic fields from the pair of front and back side shield antenna elements to shield the electromagnetic waves to be shielded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave shielding antenna element for shielding electromagnetic waves and an electromagnetic wave shield using the same.

[0002]

2. Description of the Related Art As a conventional electromagnetic wave shield, for example, one disclosed in Japanese Patent Application Laid-Open No. 10-126091 is known. In this conventional example, a linear antenna element having a length that resonates with a radio wave to be shielded is used as an electromagnetic shielding element, and an electromagnetic field reflection equivalent area (scattering aperture area) or an electromagnetic field reflection equivalent volume (scattering aperture volume) of the element is used. ), A window glass having electromagnetic shielding performance in which the linear antenna elements are regularly arranged on the glass surface or between the glass plates to scatter and attenuate radio waves with the linear antenna element.

[0003]

However, in the above-mentioned conventional example, electromagnetic waves are scattered by arranging the linear antenna elements on the glass surface or between the glass members. Considering the case of shielding electromagnetic waves, the electromagnetic field reflected equivalent area of each antenna element, 77.4Cm ² becomes, the cover window glass area of 10,000 cm ² is necessary to arrange as many as the antenna elements 100 or more There is an unsolved problem that visibility is obstructed, and there is an unsolved problem that the electromagnetic wave shielding efficiency is significantly reduced when the polarization plane of the electromagnetic wave is different from the polarization plane of the linear antenna element. .

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the conventional example, and it is possible to widen a reception range and efficiently block electromagnetic waves having various polarization planes. It is an object of the present invention to provide an electromagnetic wave shielding element that can be used and an electromagnetic wave shielding body using the same. Another object of the present invention is to provide an electromagnetic wave shield capable of efficiently shielding an electromagnetic wave by suppressing the radiation source of the electromagnetic wave.

[0005]

In order to achieve the above object, an antenna element for shielding electromagnetic waves according to claim 1 comprises a small dipole antenna element having a length sufficiently short with respect to the wavelength of the electromagnetic wave to be shielded and the non-electromagnetic element. It is characterized in that it is configured to be able to generate circular or elliptical polarization by combining with a small loop antenna element having a sufficiently short circumference with respect to the wavelength of the shielded electromagnetic wave.

According to the first aspect of the present invention, elliptical polarization including circular polarization is generated by combining a small dipole antenna element and a small loop antenna element. Electromagnetic waves can be efficiently detected and shielded. Further, the electromagnetic wave shield according to claim 2 includes a minute dipole element having a sufficiently short length with respect to the wavelength of the shielded electromagnetic wave and a minute loop antenna element having a circumferential length sufficiently short with respect to the wavelength of the unshielded electromagnetic wave. Electromagnetic wave shielding antenna elements that combine to generate elliptical polarization are arranged on the front and back of the substrate at required intervals so as to form a pair, and the currents of the pair of electromagnetic wave shielding antenna elements are configured to be in opposite phases to each other It is characterized by.

In the invention according to claim 2, in addition to the effect of the invention according to claim 1, a pair of electromagnetic wave shielding antenna elements which resonate with the shielded electromagnetic wave to be shielded are provided on both front and back surfaces of the substrate. Are configured so that the currents of the electromagnetic wave shielding antenna elements have phases opposite to each other,
One electromagnetic wave shielding antenna element can detect an electromagnetic wave, and the other electromagnetic wave shielding antenna element can emit an electromagnetic wave having a phase opposite to that of the electromagnetic wave shielding antenna. Suppress.

Further, the electromagnetic wave shield according to claim 3 is
In the invention according to claim 2, while directly supplying power from a power supply to one of the pair of electromagnetic wave shielding antenna elements,
On the other hand, power is supplied from a power supply via an inverter. According to the third aspect of the present invention, a pair of electromagnetic wave shielding antenna elements are fed from the power supply so as to be in opposite phases to each other, so that the reception range of the pair of electromagnetic wave shielding antenna elements is widened and the unit area is increased. It is possible to reduce the number of electromagnetic wave shielding antenna elements per unit.

Further, an electromagnetic wave shield according to a fourth aspect is characterized in that, in the invention according to the first or second aspect, the substrate is formed of a translucent substrate. According to the fourth aspect of the present invention, since the electromagnetic wave shielding antenna element is provided on the translucent substrate, it is possible to form a window glass capable of shielding electromagnetic waves while securing a view.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a first embodiment of the present invention, and FIG. 2 is an enlarged sectional view of FIG. 1. In the drawing, reference numeral 1 denotes a window glass having a light-transmitting property as a substrate. A number of electromagnetic wave shielding antenna elements FA1 to F which are respectively paired on the outer front side and the inner rear side.
An and RA1 to RAn (n is a positive integer) are arranged at predetermined intervals.

Here, a pair of electromagnetic wave shielding antenna elements F
As shown in FIG. 2, each of A1 to FAn and RA1 to RAn is configured to generate a circular polarization included in the elliptical polarization by combining a micro dipole antenna element MD and a micro loop antenna element ML. . The small dipole antenna element MD is a shielded electromagnetic wave (for example, ISM (In
1/16 (= 0.7) of the wavelength λ (= 12 cm) of the 2.4 GHz electromagnetic wave that forms the dustrial Scientific Medical) band
5 cm) or less.

The small loop antenna element ML is a shielded electromagnetic wave (for example, ISM (Industrial Scientific Medica) which is used for shielding with a circumference L of a rod-shaped element formed in a circular shape.
l) A wavelength λ (= 12c) of a band of 2.4 GHz electromagnetic wave)
m) is selected to be 1/16 (= 0.75 cm) or less. Then, the electromagnetic wave shielding antenna elements FA1 to FAn
The conditions for generating circularly polarized waves in RA1 to RAn are set as follows.

That is, the small dipole antenna element M
For D, it can be the electric field strength E _D is expressed by the following equation (1). E _D = (jkl / 4π) (μ / ε) ^1/2 (e ^−jkr / r) sin θ (1) where k is a complex number, I is a current flowing through the small dipole antenna element MD, and l is a small Dipole antenna element M
The length of D, μ is magnetic permeability, ε is dielectric constant, r is distance, θ is Z
The angle between the axis.

Further, for the small loop antenna element ML, the electric field intensity E _R can be expressed by the following equation (2). E _R = (ωμkI ′S / 4π) (e ^−jkr / r) sin θ (2) where I ′ is a current flowing through the small loop antenna element ML, and S is an area S surrounded by the small loop antenna element RA.
It is.

Then, the small dipole antenna element MD
In order for the composite wave of the small loop antenna element ML to become a circularly polarized wave, the wavefronts of the electromagnetic waves generated by the antenna elements MD and ML need to be shifted by 90 degrees from each other.
_R = must be ± jE _D. Therefore, the condition for generating a circularly polarized wave by the minute dipole antenna element MD and the minute loop antenna element ML is as follows from the above equations (1) and (2): Il = ± kI ′S (3)

For this reason, the small dipole antenna element M
In order to generate a circularly polarized wave in D and the small loop antenna element ML, the currents I and I 'of the two are adjusted, the length 1 of the small dipole antenna element MD is adjusted, or the small loop antenna element ML is It is sufficient to adjust the area S by changing the circumference to satisfy the condition of the above equation (3).

On the other hand, in order to shield the electromagnetic waves propagating from the outside, the electromagnetic waves are detected by the electromagnetic wave shielding antenna elements FA1 to FAn on the front side facing the incoming electromagnetic waves, and the electromagnetic waves for canceling the detected electromagnetic waves are reflected on the rear side. Of the electromagnetic wave shielding antenna elements RA1 to RAn. For this reason, the front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA
1 to RAn only need to be in opposite phases, so that the electromagnetic wave shielding antenna elements FA1 and RA
1, the small dipole antenna element MD and the small loop antenna element ML in FAn and RAn are connected as shown in FIG.

That is, as shown in FIG. 3, the small loop antenna elements ML have two substantially circular loop parts LP1 and LP2 partially open, and a short parallel straight line part connecting these open parts. An eight-shaped loop antenna element LA formed by SL1 and SL2 is formed, and this eight-shaped loop antenna element LA is connected to each of the loop parts LP1 and LP2 and the straight parts SL1 and SL2 as shown in FIG. The two loop portions LP1 and LP2 are opposed to each other in parallel at a distance of the straight portions SL1 and SL2 by bending at the portions, and the loop portions L facing each other.
P1 and LP2 form a pair of micro loop antenna elements ML through which currents of opposite phases flow.

On the other hand, as for the small dipole antenna element MD, as shown in FIG. 2, the left end of the small dipole antenna element MD on the front side is connected to the right end of the small dipole antenna element MD on the back side via a connection line LC1. ,
The right end of the small dipole antenna element MD on the front side is connected to the left end of the small dipole antenna element MD on the back side via the connection line LC2, and the two small dipole antenna elements are connected so that currents of opposite phases flow to each other. I have.

A pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RAn are arranged inside the window glass 1 with the small dipole antenna element MD facing up and down, and the center of the small dipole antenna element MD in the longitudinal direction. A minute loop antenna element ML is set in a plane orthogonal to the minute dipole antenna element MD with the position as a center point.
It is buried in alignment with the arrangement. In addition, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and R
The arrangement intervals of A1 to RAn in the window glass surface direction are selected according to the reception sensitivity of the pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RAn so that the shielded electromagnetic waves do not pass through. .

The electromagnetic wave shielding antenna elements FA1 to FA1
To embed FAn and RA1 to RAn in the window glass 1, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and a small dipole antenna element MD of RA1 to RAn are linearly connected by an insulator in a glass mold. 4 and the small loop antenna element M of FIG.
The molten glass was poured in a state where L was positioned, and FIG.
And one of the small loop antenna elements ML as shown by the broken line.
And a small dipole antenna element MD
Is formed, and molten glass is poured again into the surface of the glass plate from which the half of the small dipole antenna element MD protrudes, and a pair of front and back electromagnetic wave shielding antenna elements FA1 to FA1 shown in FIG. FAn and RA1 to RA
It is desirable to form a window glass 1 in which n is embedded.

Next, the operation according to the first embodiment will be described. Now, as shown in FIG. 2, the window glass 1 is made of a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA.
1 to RAn antenna elements FA1 to FA for shielding electromagnetic waves
n is an outdoor side, and the electromagnetic wave shielding antenna elements RA1 to R
The case where An is arranged as the indoor side will be described. When an electromagnetic wave to be shielded from the outside arrives, the electromagnetic wave is detected by the outer electromagnetic wave shielding antenna elements FA1 to FAn and resonated, so that the current generated thereby causes the electromagnetic wave shielding antenna elements RA1 to RA1 on the opposite side. RAn
And radiates an electromagnetic wave having a phase opposite to that of the electromagnetic wave arriving from the outside detected from the electromagnetic wave shielding antenna elements RA1 to RAn. Therefore, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RAn
The combined electromagnetic field is canceled, unnecessary electromagnetic waves are shielded, and the transmission of the electromagnetic waves to the indoor side can be efficiently prevented.

At this time, as shown in FIG. 5, circular electromagnetic waves are generated by the electromagnetic shielding antenna elements FA1 to FAn on the outdoor side. Even when the plane of polarization of the incoming shielded electromagnetic wave is not determined, the electromagnetic wave shielding antenna elements FA1 to FAn on the outdoor side can reliably capture the electromagnetic wave that cancels out the captured shielded electromagnetic wave. By radiating from the electromagnetic wave shielding antenna elements RA1 to RAn,
The combined electromagnetic field of the pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RAn can be surely canceled.

As described above, according to the first embodiment, the electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RA1 for generating circularly polarized waves by combining the minute dipole antenna element MD and the minute loop antenna element ML.
By configuring n, even if the polarization plane of the electromagnetic wave arriving at the window glass 1 is not specified and is wide-ranging, transmission to the indoor side can be reliably prevented.

Also, the minute loop antenna elements ML constituting the electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RAn embedded in the window glass 1 are formed by bending the figure-eight loop antenna element LA. In addition, the configuration can be simplified and the manufacturing can be easily performed.
In the first embodiment, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RA
Although the case where the small loop antenna element ML constituting n is constituted by one loop antenna element LA has been described, the present invention is not limited to this. As shown in FIG. These may be provided separately and connected via an inverter IN for inverting the phase of the induced power.
A 180-degree phase shifter IN can be applied instead of N.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to RA
By supplying power to n, the reception range is expanded. That is, in the second embodiment, as shown in FIG. 7, one micro dipole antenna element MD and a micro loop of one of a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAm and RA1 to RAm (m is a positive integer). Matching devices AJDm and AJD for each of the antenna elements ML
Power is supplied from the feed circuit VC via JLm, and the other small dipole antenna element MD and small loop antenna element ML are connected to the inverter IN and the matching device AJDm, respectively.
And AJLm to supply power from the power supply circuit VC.

Here, in the matching circuits AJ1 to AJm, by adjusting the current flowing through the small dipole antenna element MD and the small loop antenna element ML, while satisfying the condition of the above-described equation (3) for generating the circularly polarized wave, Adjust the reception sensitivity to expand the reception range. The power supply circuit VC has a reference antenna RA for detecting the state of the shielded electromagnetic wave to be shielded outside the room, and generates power supply having an amplitude synchronized with the amplitude of the shielded electromagnetic wave detected by the reference antenna RA. This feed power is supplied to matching devices AJD1-AJDm and AJD via feed line VL1.
L1 to AJLm and matching devices AJD1 to AJDm and A via inverter IN and power supply line VL2.
It is configured to output to JL1 to AJLm.

According to the second embodiment, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAm and RA1 to RA1 are used.
Matching devices AJD1 to AJDm and AJL1 to RAm
Since AJLm is provided, these matching devices AJD1
AJDm and AJL1 to AJLm are adjusted to form a pair of front and back electromagnetic wave shielding antenna elements FA1 to FA.
m and RA1 to RAm, it is possible to generate an accurate circularly polarized wave corresponding to the frequency of the desired shielded electromagnetic wave, and from the power supply circuit VC to each of the electromagnetic wave shielding antenna elements FA1 to FAm and RA1 to RAm. By supplying power, the reception sensitivity can be improved and the reception range can be expanded, so that the electromagnetic wave shielding antenna elements FA1 to FAm
And the arrangement intervals of RA1 to RAm can be set longer than in the first embodiment. For this reason, electromagnetic waves can be shielded without impairing the translucency of the window glass 1.

In the first and second embodiments, the case where the present invention is applied to the window glass 1 has been described. However, the present invention is not limited to this. It can be applied to products for which transmission or emission of electromagnetic waves is desired to be suppressed, such as glass or display screens of personal computers. In the first and second embodiments, the case where glass is used as the light-transmitting substrate has been described. However, the present invention is not limited to this, and a light-transmitting synthetic resin sheet may be used. Can also. Further, a pair of front and back electromagnetic wave shielding antenna elements FA1 to FAn and RA1 to R1 are not limited to the light-transmitting substrate but may be formed on a light-transmitting substrate such as a building material such as a blind or a wall material.
An may be provided.

Further, in the first and second embodiments, the case where the circularly polarized wave is generated by the minute dipole antenna element MD and the minute loop antenna element ML has been described. However, the present invention is not limited to this. Alternatively, elliptical polarization may be generated instead of complete circular polarization.

[0031]

As described above, according to the first aspect of the present invention, elliptical polarization including circular polarization is generated by combining a small dipole antenna element and a small loop antenna element. In addition, it is possible to efficiently detect and shield an electromagnetic wave to be blocked having various polarization planes.

According to the second aspect of the present invention, a pair of electromagnetic wave shielding antenna elements resonating with the shielded electromagnetic wave to be shielded are provided on both front and back surfaces of the substrate, and the current of these electromagnetic wave shielding antenna elements is reduced. Since the antennas are configured to have phases opposite to each other, electromagnetic waves having polarization planes in all directions are reliably detected by one antenna element for shielding electromagnetic waves, and the other antenna element for shielding electromagnetic waves emits electromagnetic waves having the opposite phase to that of the antenna element. Therefore, the electromagnetic field synthesized by the two can be canceled to suppress the emission of unnecessary electromagnetic waves.

Further, according to the third aspect of the present invention, power is supplied to the pair of front and back electromagnetic wave shielding antenna elements from the power supply so that the phases are opposite to each other, so that the reception range of the pair of electromagnetic wave shielding antenna elements is increased. The effect is obtained that the number of antenna elements for shielding electromagnetic waves per unit area can be reduced by increasing the size. Still further, according to the invention according to claim 4, since the electromagnetic wave shielding antenna element is provided on the translucent substrate, the window glass can shield electromagnetic waves having polarization planes in all directions while securing the view. Can be formed.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of FIG.

FIG. 3 is a front view showing a small loop antenna element LA.

FIG. 4 is a perspective view showing an electromagnetic wave shielding antenna element formed by bending the small loop antenna element of FIG. 3;

FIG. 5 is an explanatory diagram showing circularly polarized waves generated by an electromagnetic wave shielding antenna element.

FIG. 6 is an enlarged sectional view showing a modified example of the small loop antenna element according to the first embodiment.

FIG. 7 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 Window glass FA1 to FAn Front-side electromagnetic wave shielding antenna element RA1 to RAn Backside electromagnetic wave shielding antenna element MD Micro dipole antenna element ML Micro loop antenna element IN Inverter AJD1 to AJDm, AJL1 to AJLm Matching device VL1, VL2 Electric wire VC power supply circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K090 AA12 AB02 EB10 FA10 3L086 AA01 BC06 DA02 5E321 AA04 AA33 GG05 GH01 5J020 BA15 BD01 EA04 EA08 EA10

Claims (4)

[Claims] An elliptically polarized wave is generated by combining a small dipole element having a sufficiently short length with respect to the wavelength of the shielded electromagnetic wave and a small loop antenna element having a sufficiently short circumference with respect to the wavelength of the unshielded electromagnetic wave. An antenna element for shielding electromagnetic waves, wherein the antenna element is configured to be capable of being used. 2. An elliptical polarization is generated by combining a small dipole element having a sufficiently short length with respect to the wavelength of the shielded electromagnetic wave and a small loop antenna element having a sufficiently short perimeter with respect to the wavelength of the shielded electromagnetic wave. An electromagnetic wave shielding body characterized in that the electromagnetic wave shielding antenna elements to be arranged are arranged on the front and back of the substrate at required intervals so as to form a pair, and the currents of the pair of electromagnetic wave shielding antenna elements are in opposite phases to each other. . 3. The electromagnetic wave shield according to claim 2, wherein one of the pair of antenna elements for electromagnetic wave shield is directly supplied with power from a power supply and the other is supplied with power from the power supply via an inverter. body. 4. The electromagnetic wave shield according to claim 2, wherein the substrate is formed of a translucent substrate.