JP4003748B2 - Loop antenna - Google Patents

Description

The present invention relates to a substantially planar loop antenna made of metal wiring.
This antenna is very useful in the case of constituting a substantially planar small antenna for receiving or transmitting radio waves.

9 and 10 illustrate plan views of a conventional loop antenna in which a wiring pattern is developed on a substantially plane. The loop antenna 110 of FIG. 9 is obtained by widening the available communication band by using metal wirings L ₁₁₁ , L ₁₁₂ , L ₁₁₃ , and L ₁₁₄ to quadruple the antenna loop.
Further, the loop antenna 120 of FIG. 10 has a wide wiring width of the wiring pattern (metal wiring L ₁₂₁ ) in order to obtain substantially the same effect as such a multi-line configuration.

Further, as a conventional loop antenna using a combination of these broadbanding techniques, for example, the one described in Patent Document 1 below is widely known. This Patent Document 1 discloses a loop antenna in which wide strip-shaped metal wires are arranged and fixed on a surface of a plate-like insulator in a multiple loop shape.
JP 2000-269724 A

However, if a conventional wideband technique such as the above-described multiple looping or widening of wiring patterns is employed, the following problems are difficult to avoid.
(Problem 1) When a target loop antenna is fixed to a translucent insulator such as glass or resin, the translucency of the insulator is hindered.
(Problem 2) In particular, when the insulator is a window glass of a vehicle, it is disadvantageous in terms of securing the sight of the occupant and the aesthetic appearance of the vehicle.

  The present invention has been made to solve the above-described problems. The object of the present invention is to realize a small antenna having a substantially planar shape that matches in a wide band, and to reduce the thickness of the metal wiring. Or reducing the number of loops.

In order to solve the above problems, the following means are effective .

According to a first means of the present invention, in a loop antenna composed of a metal wiring developed substantially on a plane, a metal wiring p forming one open curve having two end points close to each other, and a single wiring A metal wiring q that forms a simple closed curve and a metal wiring r that forms a single simple closed curve. The metal wiring p and the metal wiring q share the line s with each other, and the metal wiring p and the metal wiring r. Share the line t with each other, the line s and the line t do not have an intersection or contact with each other, the metal wiring q and the metal wiring r are arranged apart from each other, and two sets of feeding points at the above two end points 1 is provided, and a portion pp of the metal wiring p located between the metal wiring q and the metal wiring r is provided with a power feeding portion O, and the metal wiring is connected through the power feeding portion O by this portion pp. connecting a q and the metal wire r, substantially parallel with the metal wiring p A Jo metal wiring to form a folded dipole comprising metal wiring p, q, the outermost loop Z formed in the remaining portion except for the line s and line t from r, the line s and line t is disposed inside the outermost loop Z, is that consistent with continuous frequency band including the resonance frequency f ₁ of the resonance frequency f ₂ and the outermost loop Z of folded dipole.

Further, the second means of the present invention is the distance D ₁ between the part ss of the line s located near the power feeding part O and the part tt of the line t located near the power feeding part O in the first means. It is to arrange them so as to face each other.

The third means of the present invention is such that, in the second means, 0.005λ ₂ ≦ D ₁ ≦ 0.05λ ₂ is established for the wavelength λ ₂ corresponding to the resonance frequency f ₂ . , Setting the distance D ₁ .

Further, a fourth means of the present invention is the above-described first to third means, wherein any of the metal wirings constituting the loop antenna is connected to one center line passing through the feeding portion O. It is to form in a substantially line symmetrical form.

The fifth means of the present invention is to make the resonance frequency f ₂ higher than the resonance frequency f ₁ in any one of the first to fourth means.

A sixth means of the present invention is to provide a detour route recessed inward in the outermost peripheral loop Z in any one of the first to fifth means.

According to a seventh means of the present invention, in any one of the first to sixth means, the interval D ₂ between the substantially parallel metal wires forming the folded dipole corresponds to the resonance frequency f ₂ . The setting is such that 0.01λ ₂ ≦ D ₂ ≦ 0.2λ ₂ holds with respect to the wavelength λ ₂ .

Further, an eighth means of the present invention is to embed, fit, and paste the loop antenna formed using any one of the first to seventh means into a window glass of a vehicle. It is fixing by welding or application.
By the above means of the present invention, the above-mentioned problem can be effectively or rationally solved.

The effects obtained by the above-described means of the present invention are as follows.
That is, according to the first means of the present invention, it is possible to configure a small antenna having a substantially planar shape that matches in a wide band with a metal wiring shorter than the conventional one.
Since the resonance mode differs between the loop antenna and the dipole antenna, according to the configuration of the present invention, the resonance frequencies f ₁ and f ₂ can be controlled independently. That is, design parameters such as the shape and length of each part of the antenna related to the resonance frequencies f ₁ and f ₂ can be provided independently. Therefore, according to the configuration of the present invention, it is possible to configure a loop antenna that matches over a wide band.
Furthermore, according to the above configuration, the entire antenna can be formed with a configuration in which the lines s and t are added to the single loop configuring the loop antenna.

Due to these circumstances, when an antenna having a reception band (or transmission band) of the same width is formed by metal wiring or the like, in the above configuration, the sum of the lengths of the line s and the line t is the same frequency band. Thus, in the conventional multiple loop structure that gives characteristics at substantially the same level, it is possible to make the length shorter than the sum of the loop lengths of the loops that need to be arranged inside the outermost loop.
Therefore, according to the present invention, it is possible to configure a small antenna having a substantially planar shape that matches in a wide band with a smaller number of loops or a shorter wiring length than in the prior art. Can also be solved.

That is, according to the present invention, the following effects can be obtained at the same time.
(1) When a target loop antenna is fixed to a light-transmitting insulator, the light-transmitting property of the insulator is not easily disturbed.
(2) In particular, when the insulator is a window glass of a vehicle, it is advantageous in terms of securing the occupant's field of view and aesthetics of the vehicle.
Moreover, according to the structure of this invention, the material cost of a metal wire can be suppressed effectively irrespective of the fixed form of a loop antenna.

Further, according to the first means of the present invention, the loop antenna of the present invention can be configured more specifically and reliably.
However, the open curve or simple closed curve referred to here may be interpreted as the center line of the metal wiring. Since this metal wiring is actually formed by a known metal conductor such as a metal wire, of course, it has a thickness and a volume if strictly speaking.
The first means utilizes the stereotypes open curve or a simple closed curve like circumferential intelligence (image), it is intended to more specifically find easy explanation (redefined).

Further, according to the second aspect of the present invention, by adjusting the distance D _1, it is possible to adjust the input impedance of the above folded dipole. Therefore, according to the above configuration, the voltage standing wave ratio (VSWR) at the resonance frequency f ₂ of the folded dipole can be easily suppressed (minimized) by adjusting the distance D ₁ .
An appropriate range of the distance D ₁ at this time is 0.005λ ₂ ≦ D ₁ ≦ 0.05λ ₂ ( third means of the present invention).

The antenna structure described above is not necessarily formed in a line symmetrical form. However, according to the fourth means of the present invention, the degree of freedom of the shape of the antenna wiring can be reduced, so that the design work of the antenna wiring pattern can be simplified. That is, the loop antenna of the present invention is not expected to have a special effect on the reception characteristics (or transmission characteristics) by making it asymmetrical on the left and right. It becomes easier to predict characteristics (or transmission characteristics).
However, it is more desirable to finally determine the wiring pattern of the loop antenna by comprehensively considering the shape and area of the installation place and further visual effects.

Further, according to the fifth means of the present invention, the bandwidth of the reception band (or transmission band) can be effectively secured.
If the resonance frequency difference (f ₂ −f ₁ > 0) is set as large as possible within the range in which the reception band (or transmission band) is not separated into two, the bandwidth of the target reception band (or transmission band) is effective. Can be secured widely. This difference is desirably as large as possible within a range where the reception band (or transmission band) is not separated into two.

According to the sixth means of the present invention, a longer loop length can be ensured with a smaller installation area. This effectively contributes to at least one of miniaturization of the antenna and securing of a wide reception bandwidth (or transmission bandwidth).

In addition, according to the seventh aspect of the present invention, by adjusting the distance D _2, it is possible to adjust the input impedance of the above folded dipole. Therefore, according to the above configuration, the voltage standing wave ratio (VSWR) at the resonance frequency f ₂ of the folded dipole can be easily suppressed (minimized) by adjusting the distance D ₂ . An appropriate range of the distance D ₂ at this time is 0.01λ ₂ ≦ D ₂ ≦ 0.2λ ₂ .

Moreover, in the loop antenna of the present invention, the wiring length of the metal wiring to be used can be suppressed shorter or thinner than before, so when this loop antenna is disposed on the window glass of an automobile, This is advantageous in terms of securing the occupant's field of view and the aesthetic appearance of the vehicle ( eighth means of the present invention).

Hereinafter, the present invention will be described based on specific examples.
However, the embodiments of the present invention are not limited to the following examples. In each of the following embodiments, specific embodiments are disclosed centering on a reception antenna, but it goes without saying that the loop antenna of the present invention can also be used as a transmission antenna.

FIG. 1 shows a plan view of the loop antenna 10 of the first embodiment. The wire pp ₁₀ is a metal wiring that is located on the right side of the power supply unit O ₁₀ shown in the enlarged view at the lower right of FIG. 1 and connects the end point α and the point k shown in the approximate center of FIG. a part (pp ₁₀ right section), is a general term for the metal wiring portion connecting the end point β and point h located on the left side of the feeding section O ₁₀ (pp ₁₀ left portion). Starting from this end point α, the corners a, b, c, d are sequentially circulated in the counterclockwise direction, and finally the outermost peripheral loop Z is made of a metal wire on the route returning to the end point β on the left side of pp ₁₀ above. Is formed. Further, the line s ₁₀ is a line that connects only two points g and h shown in the figure on the outermost loop Z through only the rectangular inner region surrounded by the outermost loop Z. Not located in. Similarly line t ₁₀ passes through the inside of the outermost loop Z (on the rectangular inner area), 2 points j on the outermost loop Z, a line connecting the k. The line s ₁₀ and the line t ₁₀ have neither an intersection nor a contact point.

Let U be a two-dimensional region surrounded by the line segment connecting the left and right end points α and β of the wire pp ₁₀ and the outermost peripheral loop Z. That is, the two-dimensional area U coincides with the rectangular inner area having the points a, b, c, and d as vertices. Therefore, if the two-dimensional region U is considered as a set of points, it can be written as U 例 え ば s ₁₀ , t ₁₀ , for example. This is because the lines s ₁₀ and t ₁₀ are metal wires passing over the rectangular inner region surrounded by the outermost peripheral loop Z as described above.

More specifically, the two-dimensional area U is composed of the sum area of the three two-dimensional areas P ₁₀ , Q ₁₀ , and R ₁₀ shown in FIG. 1 and the two lines s ₁₀ and t _10. The However, P ₁₀ , Q ₁₀ , R ₁₀ , s ₁₀ , and t ₁₀ do not cross each other. That is, U = P ₁₀ ∪Q ₁₀ ∪R ₁₀ ∪s ₁₀ ∪t ₁₀ and “∀A∈ {P ₁₀ , Q ₁₀ , R ₁₀ , s ₁₀ , t ₁₀ }, ∀B∈ {P ₁₀ , Q ₁₀ , R ₁₀ , s ₁₀ , t ₁₀ } and A ≠ B ”⇒“ A∩B = φ ”.
The metal wiring (: wire p ₁₀ ) forming an open curve surrounding the two-dimensional region P ₁₀ and the metal wiring (: wire q ₁₀ ) forming the circumference (: simple closed curve) of the two-dimensional region Q ₁₀ are: Some metal wiring (: line s ₁₀ ) is shared. Similarly, the metal wiring (: wire p ₁₀ ) surrounding the two-dimensional region P ₁₀ and the metal wiring (: wire r ₁₀ ) forming the circumference (: simple closed curve) of the two-dimensional region R ₁₀ are part of the metal wiring. Share: (line t _10).

The wire p _10, points of the alpha, the β and the two end points, say just surrounds part of the metal wire just proportion two-dimensional region P ₁₀ having a substantially T-shaped in FIG. 1, the wire p ₁₀ is A substantially T-shaped folded dipole provided with a power feeding portion O ₁₀ is formed.
Reference sign D ₂ represents the distance between two lines of the substantially parallel shape of the folded dipole. That is, the folded dipole has a longitudinal direction in the transverse direction (: x-axis direction) and is about 3 to 4 times longer in the transverse direction than the longitudinal direction (: y-axis direction). The left end of the T-shape is bent at a right angle in the negative direction in the y-axis direction at the portion ahead of the point c, and the portion at the right end of the T-shape is y at the portion ahead of the point b. It is bent at a right angle in the negative axial direction. In addition, the power supply unit O ₁₀ is provided at the approximate center of the T-shaped leg (lowermost part).

In other words, wire p ₁₀ surrounding the two-dimensional region P ₁₀ of the substantially T-shaped constitutes an open curve, this opens the two endpoints said feeding portion of the curve O ₁₀ (enlarged view of FIG. 1) It corresponds to the left and right end points α and β of the placed wire pp ₁₀ . That is, the two end points α and β of the wire p ₁₀ forming an open curve surrounding the two-dimensional region P ₁₀ are opposed to each other at the power feeding unit O ₁₀ . A portion pp ₁₀ of the wire p ₁₀ having the power feeding section O ₁₀ is circumferential in the two-dimensional region Q _10: the point h on wire q ₁₀ to form a (simple closed curve), circumference of the two-dimensional region R ₁₀ and the k point on the wire r ₁₀ to form a (simple closed curve), connects through the power supply unit O _10.

Also, the wire p _10, the wire q _10, from the wire r _10, the remaining portion except for the line s _10, line t ₁₀ described above, three two-dimensional regions P _10, Q _10, the sum of R ₁₀ regions A substantially rectangular open curve is formed. Of course, this open curve is a portion corresponding to the outermost peripheral loop Z, thereby forming a loop portion in the target loop antenna.

Part ss ₁₀ of the line s ₁₀ is opposed in parallel with the part tt ₁₀ of the line t _10. In other words, the portion of the line s _10, referred to as a portion ss ₁₀ a portion facing parallel lines t _10, the portion of the line t _10, tt ₁₀ part and the part which faces in parallel lines s ₁₀ Call it.
These parts or less, facing part ss _10, tt _10, or may be referred to as root portion ss _10, tt _10. Moreover, combined with the facing part ss ₁₀ and the facing portion tt _10, hereinafter sometimes referred to as a stub (ss _10, tt _10). The distance D ₁ represents the interval between ss ₁₀ and tt _10, and this distance D ₁ is hereinafter referred to as the width of the stub (ss ₁₀ , tt ₁₀ ). This stub (root portion ss ₁₀ , tt ₁₀ ) contributes to power feeding.

The appropriate range of the stub width D ₁ (: the distance between the wires ss ₁₀ and tt ₁₀ ) is 0.005λ ₂ ≦ D ₁ ≦ 0.05λ ₂ , and the stub width D ₁ is this appropriate range, The width of the reception band (or transmission band) where the voltage standing wave ratio (VSWR) at the feeding point O ₁₀ at the resonance frequency f ₂ is minimized or the voltage standing wave ratio (VSWR) is 2 or less. Is optimized so that is maximized.
Further, an appropriate range of the distance D ₂ between the two lines of the folded dipole is 0.01λ ₂ ≦ D ₂ ≦ 0.2λ ₂ , and the distance D ₂ is within this appropriate range, and the voltage constant at the resonance frequency f ₂ is set. Optimized so that the standing wave ratio (VSWR) is minimized or the width of the reception band (or transmission band) where the voltage standing wave ratio (VSWR) is 2 or less is maximized. .

FIG. 2 illustrates the reflection characteristic (VSWR) at the feeding point O ₁₀ of the loop antenna 10 of the first embodiment. The frequency f ₁ is the resonance frequency of the loop in the target loop antenna, and the frequency f ₂ is the resonance frequency of the folded dipole. The wavelength λ ₁ of the radio wave received most sensitively by the loop substantially matches the length L ₁ of the loop. Therefore, the product of the resonance frequency f ₁ and the loop length L ₁ substantially matches the speed of light c. Further, the wavelength λ ₂ of the radio wave received most sensitively by the folded dipole substantially coincides with the length 2L ₂ that is twice the total length of the folded dipole. Accordingly, the product of the resonance frequency f ₂ and the total length L _{2 of the} folded dipole substantially matches the half value of the speed of light c.
However, in FIG. 2, the frequencies f ₁ and f ₂ are expressed by normalization using an appropriate frequency f ₀ between them. The frequency f _{0 in} FIG. 2 substantially matches the center frequency in the frequency band (reception band or transmission band) where the voltage standing wave ratio (VSWR) is 2 or less.

As can be seen from FIG. 2, the loop antenna 10 of the first embodiment is formed by a simple wiring structure in which the line s ₁₀ and the line t ₁₀ are added to the outermost peripheral loop Z, and is used. Although the total length of the wires is relatively short with respect to the wavelengths λ ₁ and λ ₂ , the reception band or transmission band of the loop antenna 10 (the voltage standing wave ratio is 2 or less) Frequency band) is very wide. This bandwidth reaches about 41% (0.80 to 1.21) of the center frequency f ₀ .

Therefore, for example, if the total length in the y-axis direction of the loop antenna 10 is 6 cm and the total length in the x-axis direction is 23 cm, λ ₁ ≈58 cm, f ₁ ≈520 MHz, f ₀ ≈590 MHz, and the bandwidth of the reception band is It is about 242 MHz. That is, in this case, if the loop antenna 10 is used, a television broadcast in a frequency band of 469 MHz to 711 MHz can be received. That is, according to the above configuration based on the present invention, a total of 40 channels of terrestrial digital television broadcasting in Japan can be received with one antenna (the loop antenna 10).

3A, 3B, and 3C are graphs illustrating the reception sensitivity (radiation pattern) at each frequency (f = 0.8f ₀ / f ₀ /1.2f ₀ ) of the loop antenna 10. As can be seen from FIG. 3, the loop antenna 10 exhibits a substantially 8-shaped directivity in the y-axis direction at any frequency within the reception band (0.8 f _{0 to} 1.21 f ₀ ).

Further, since the loop antenna 10 of the first embodiment has few or short wiring, when this antenna is fixed to a window glass or the like by embedding, fitting, or pasting, the case of a conventional multi-loop antenna The translucency can be ensured better than that.
For this reason, the loop antenna 10 of the first embodiment is very advantageous in terms of securing the occupant's field of view and aesthetics of the vehicle, particularly when it is disposed on a window glass of a vehicle or the like. In addition, this advantage is particularly noticeable because a plurality of antennas must be prepared when mobile communication in a vehicle or the like is performed by adaptive reception or diversity reception.

  FIG. 4 is a plan view of the loop antenna 20 of the second embodiment. The loop antenna 20 is obtained by modifying the loop antenna 10 by providing a bypass with respect to the outermost peripheral loop Z of the loop antenna 10 of the first embodiment. Therefore, the other configuration is very similar to the loop antenna 10 of the first embodiment.

That is, the line s ₂₀ is a line connecting the two points g and h on the outermost loop Z inside the outermost loop Z (on the inner region). Similarly, the line t ₂₀ is located inside the outermost loop Z. This line connects the two points j and k on the outermost loop Z.

Similarly to the first embodiment, U is a two-dimensional region surrounded by the line segment connecting the two end points of the wire pp ₂₀ arranged on the power feeding unit O ₂₀ and the outermost peripheral loop Z. At this time, the two-dimensional region U is composed of a sum region of three two-dimensional regions P ₂₀ , Q ₂₀ , and R ₂₀ shown in the figure and the two lines s ₂₀ and t ₂₀ described above. However, P ₂₀ , Q ₂₀ , R ₂₀ , s ₂₀ , and t ₂₀ do not cross each other.

Further, in the loop antenna 20, the length of the wire p ₂₀ surrounding the two-dimensional region P _20, the length and approximately matches the wire p ₁₀ of the loop antenna 10, the length of the wire q ₂₀ enclose two-dimensional region Q ₂₀ The length substantially coincides with the length of the wire q ₁₀ of the loop antenna 10, and the length of the wire r ₂₀ surrounding the two-dimensional region R ₂₀ substantially coincides with the length of the wire r ₁₀ of the loop antenna 10.

Further, the width of the stub (ss ₂₀ , tt ₂₀ ) of the loop antenna 20 is substantially equal to the width D ₁ of the stub (ss ₁₀ , tt ₁₀ ) of the loop antenna 10, and further, the substantially parallel shape of the loop antenna 20. The distance between the two lines of the folded dipole is also approximately equal to the distance D ₂ between the two lines of the substantially parallel folded dipole of the loop antenna 10.

For this reason, the matching / radiation characteristics of the loop antenna 20 of the second embodiment substantially match the matching / radiation characteristics of the loop antenna 10 illustrated in FIGS. 2 and 3.
However, a portion of the wire q ₂₀ that forms the periphery of the two-dimensional region Q ₂₀ wire qq ₂₀ is detour diverting outermost loop Z by recessing the perimeter of the two-dimensional region Q ₂₀ inwardly Is forming. Similarly bypass, wire rr ₂₀ is a portion of the wire r ₂₀ which forms the circumference of the two-dimensional area R ₂₀ are diverting outermost loop Z by recessing the perimeter of the two-dimensional region R ₂₀ inwardly Forming a road. The installation of these two detours (qq ₂₀ , rr ₂₀ ) contributes to the miniaturization of the loop antenna 20. That is, by providing such a detour, the installation area of the loop antenna 20 is further reduced while maintaining the matching / radiation characteristics of the loop antenna 10 of the first embodiment.
In this way, if the loop is recessed inward to form a detour, the installation area of the loop antenna can be effectively reduced.

FIG. 5 is a plan view of the loop antenna 30 according to the third embodiment. The loop antenna 30 is a modification of the loop antenna 10 of Example 1, the outermost loop Z of the loop antenna 30 is made substantially oval surrounding the two-dimensional region P ₃₀ having a substantially T-shaped The substantially T-shaped folded dipole formed of the metal wire p ₃₀ (⊃ (s ₃₀ ∪pp ₃₀ ∪t ₃₀ )) is deformed into a curved shape along this ellipse.

That is, the line s ₃₀ is a line connecting the two points g, h on the outermost loop Z in FIG inside the outermost loop Z, likewise, the line t ₃₀ is the outermost loop inside the outermost loop Z A line connecting two points j and k on Z. Similarly to the first embodiment, when two end points of the wire pp ₃₀ arranged on the power feeding unit O ₃₀ are connected by a line segment, a two-dimensional region surrounded by the line segment and the outermost peripheral loop Z is defined as U. And At this time, the two-dimensional region U is composed of a sum region of three two-dimensional regions P ₃₀ , Q ₃₀ and R ₃₀ shown in the figure and the two lines s ₃₀ and t ₃₀ described above. However, P ₃₀ , Q ₃₀ and R ₃₀ do not cross each other.

Also in this loop antenna 30, the length of the wire p ₃₀ surrounding the substantially T-shaped two-dimensional region P ₃₀ is substantially the same as the length of the wire p ₁₀ of the loop antenna 10 and surrounds the two-dimensional region Q ₃₀ . The length of the wire q ₃₀ is substantially the same as the length of the wire q ₁₀ of the loop antenna 10, and the length of the wire r ₃₀ surrounding the two-dimensional region R ₃₀ is substantially the same as the length of the wire r ₁₀ of the loop antenna 10. Match.

Further, the width of the stub (ss ₃₀ , tt ₃₀ ) of the loop antenna 30 is substantially equal to the width D ₁ of the stub (ss ₁₀ , tt ₁₀ ) of the loop antenna 10 and is further substantially parallel to the loop antenna 30. The distance between the two lines of the folded dipole having the shape also substantially coincides with the distance D ₂ between the two lines of the substantially parallel folded dipole of the loop antenna 10.

For this reason, the matching / radiation characteristics of the loop antenna 30 of the third embodiment substantially match the matching / radiation characteristics of the loop antenna 10 illustrated in FIGS.
Then, as specifically illustrated in FIG. 5, any part of the wiring pattern (wires p ₃₀ , q ₃₀ , r ₃₀ ) of the loop antenna of the present invention can be configured with a curve. . The square part of the figure is easy to draw people's attention visually, but it is easy to stand out, but by incorporating the curve as much as possible into the wiring shape of the antenna, the number of square parts can be reduced. It is possible to form a loop antenna having a shape that is visually negligible. Therefore, if such a loop antenna is disposed on, for example, a window glass of a vehicle, it is possible to make it easier to secure a passenger's field of view and to make it difficult to impair the aesthetics of the vehicle.

[Other variations]
The embodiment of the present invention is not limited to the above-described embodiment, and other modifications as exemplified below may be made. Even with such modifications and applications, the effects of the present invention can be obtained based on the functions of the present invention.

(Modification 1)
For example, in Examples 1 to 3 described above, the position of the power supply unit O ₁₀ is selected as the farthest (lower) portion from the resonant portion of the folded dipole (two lines that are substantially parallel and separated by a distance D ₂ ). The position of the power feeding unit O ₁₀ can be selected from any of the lower part, the center, and the upper part of the antenna.

FIG. 6A is a plan view of a loop antenna 41 formed in accordance with the present invention. In the loop antenna 41, and the line s ₄₁ and the line t ₄₁ is connected by wire pp _41, and these wires (s _41, t _41, pp ₄₁₎ are arranged on a straight line. Therefore, the loop antenna 41, the feeding section O ₄₁ is placed on top of the loop of the antenna. Further, the wire pp ₄₁ forms a part of a loop detour, and the power feeding unit O ₄₁ is located at an intermediate point of the detour. Further, neither of the lines s ₄₁ and t ₄₁ has a facing portion.

FIG. 6B is a plan view of a loop antenna 42 formed in accordance with the present invention. In the loop antenna 42, a facing part ss ₄₂ and facing portion tt ₄₂ is opposed non-parallel. Further, the right side of the wire pp ₄₂ is bent downward from the power feeding portion O ₄₂ . Further, also becomes asymmetrical shape of the left and right ends of the folded dipole formed by the wire p _42. That is, no bent portion is provided at the right end of the folded dipole of the loop antenna 42.

6-C is a plan view of a loop antenna 43 formed in accordance with the present invention. In this loop antenna 43, a facing part ss ₄₃ and facing portion tt ₄₃ is opposed non-parallel. In addition, in the wire q ₄₃ forming a simple closed curve, the lower left portion is recessed inside the closed curve. However, the area occupied by the antenna can be reduced while maintaining the loop length by forming such a recess. .
Further, in each of the loop antennas 41 to 43, a detour that passes through the power feeding unit is formed on the loop of the loop antenna.

(Modification 2)
The loop antennas 51 to 53 in FIGS. 7A, 7B, and 7C have two or more detours that increase the loop length, and the shape of the wire (pp ₅₁ / pp ₅₂ / pp ₅₃ ) in the vicinity of the power feeding unit is This is an example of being deformed asymmetrically. In addition, the positions or shapes of the detours that increase the loop length are also asymmetric in the loop antennas 51 to 53.

(Modification 3)
The loop antennas 61 to 63 shown in FIGS. 8A, 8B, and 8C are provided with a detour for increasing the loop length from the side of the loop. The detours (qq ₆₁ , rr ₆₁ / qq ₆₂ , rr ₆₂ / qq ₆₃ , rr ₆₃ ) are all formed symmetrically.

Further, in the loop antenna 63, detours that increase the loop length are provided in a total of five places, but the number of such detours is arbitrary. Further, in the loop antenna 63, the bent portions are not provided at the left and right ends of the folded dipole formed by the wire p ₆₃ , but the presence or absence and the length of the bent portions may be arbitrary.
For example, even when the above-described arbitrary modifications are implemented, the functions and effects of the present invention can be obtained based on the configuration of the present invention.

  Moreover, the effect of suppressing the material cost of the wiring pattern (metal wiring) that is inevitably caused by the reduction or reduction in the number of loops and the line width of the wiring pattern (metal wiring) is, for example, that the antenna is made of a translucent insulator This is a basic effect obtained based on the means of the present invention regardless of the fixed form of the loop antenna of the present invention.

  When the loop antenna of the present invention is arranged on a transparent insulator such as a window glass, for example, the advantage of the loop antenna is particularly remarkable. For example, it can be used in any form of use for transmission / reception of radio waves of any frequency that can be used for communication.

Plan view of the loop antenna 10 of the first embodiment. The graph which illustrates the reflective characteristic of the loop antenna 10 of Example 1 A graph illustrating the reception sensitivity of the loop antenna 10 at f = 0.8f ₀ A graph illustrating the reception sensitivity of the loop antenna 10 at f = 1f ₀ A graph illustrating the reception sensitivity of the loop antenna 10 at f = 1.2f ₀ Plan view of the loop antenna 20 of the second embodiment. Plan view of loop antenna 30 according to the third embodiment. Plan view of another modified example (loop antenna 41) Plan view of another modified example (loop antenna 42) Plan view of another modification (loop antenna 43) Plan view of another modification (loop antenna 51) Plan view of another modified example (loop antenna 52) Plan view of another modification (loop antenna 53) Plan view of another modified example (loop antenna 61) Plan view of another modified example (loop antenna 62) Plan view of another modified example (loop antenna 63) Plan view of a conventional loop antenna 110 Plan view of a conventional loop antenna 120

Explanation of symbols

10, 20,
30: Loop antenna O: Feeding part p: Wire (forms an open curve)
q: Wire (forms a simple closed curve)
r: Wire (forms a simple closed curve)
s: shared part of p and q t: shared part of p and r pp: part of p (near the power feeding part O)
ss: a part of s (opposite to tt)
tt: a part of t (opposite part with ss)
D ₁ : Distance between ss and tt D ₂ : Distance between two lines of a folded dipole having a substantially parallel shape

Claims (8)

It is a loop antenna composed of metal wiring developed on a substantially plane,
A metal wiring p forming one open curve having two end points close to each other;
Metal wiring q forming one simple closed curve;
A metal wiring r forming a simple closed curve,
The metal wiring p and the metal wire q share a line path s in each other,
The metal wiring p and the metal wiring r share a line path t to each other,
The line s and the line t do not have intersections or contacts with each other,
The metal wiring q and the metal wiring r are arranged apart from each other,
The two end points constitute one power feeding unit O composed of a pair of two power feeding points ,
A portion pp of the metal wiring p located between the metal wiring q and the metal wiring r is:
Including the power supply unit O, and
The metal wiring q and the metal wiring r are connected via the power feeding unit O,
The metal wiring p is
Forming a folded dipole having a substantially parallel metal wiring ,
The remaining part excluding the line s and the line t from the metal wiring p, q, r is
To form a outermost loop Z,
The line s and the line t are arranged inside the outermost circumferential loop Z,
The folded dipole resonance frequency f ₂ and the continuous, wherein the matching in the frequency band and to Lulu Puantena including the resonance frequency f ₁ of the outermost loop Z. A portion ss of the line s located near the power feeding unit O;
A part tt of the line t located near the power feeding unit O is:
The loop antenna according to claim 1 , wherein the loop antennas are arranged to face each other at a distance D ₁ . The distance D ₁ is
For the wavelength λ ₂ corresponding to the resonance frequency f ₂ ,
0.005λ ₂ ≦ D ₁ ≦ 0.05λ ₂
The loop antenna according to claim 2 , wherein the loop antenna is set so as to satisfy. Any of the metal wires constituting the loop antenna
4. The loop antenna according to claim 1 , wherein the loop antenna is formed so as to be substantially line symmetrical with respect to one center line passing through the power feeding portion O. 5. The resonance frequency f ₂ is
Loop antenna according to any one of claims 1 to 4 and greater than the resonant frequency f _1. The outermost loop Z is
The loop antenna according to any one of claims 1 to 5, further comprising a bypass route recessed inward. The interval D ₂ between the substantially parallel metal wires forming the folded dipole is:
For the wavelength λ ₂ corresponding to the resonance frequency f ₂ ,
0.01λ ₂ ≦ D ₂ ≦ 0.2λ ₂
The loop antenna according to any one of claims 1 to 6, wherein the loop antenna is set so as to satisfy. The loop antenna according to any one of claims 1 to 7, wherein the loop antenna is fixed to a window glass of a vehicle by embedding, fitting, pasting, welding, or coating.

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