JP2010252190A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna which can successfully receive radio wave coming from right and left sides in lateral directions relative to a travelling direction of a moving vehicle and can successfully receive digital television broadcast. <P>SOLUTION: The antenna 55 which is set up on a windshield of a car to receive radio wave in a digital television broadcast band contains a linear conductor 51 which has a length corresponding to one-wavelength λ of a specific frequency in the digital television broadcast band and is circularly bent such that an area enclosed by the linear conductor 51 forms a T shape, wherein both ends of the linear conductor 51 go close at a completion of bending of the linear conductor 51, whose both ends serve as power feeding terminals 53, 54. The power feeding terminals 53, 54 are located near a contact portion of a first area H corresponding to a crossbar area of the T enclosed by the linear conductor 51 and a second area V corresponding to a vertical bar area of the T. The second area V may be offset to a centerline of the antenna. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antenna, and more particularly to an antenna that can efficiently receive radio waves coming from the front of a mobile body or from the lateral direction of the mobile body by being attached to a radio wave reception area of a mobile body such as a vehicle.

  Conventionally, mobile bodies such as vehicles such as automobiles have been equipped with receivers for listening to broadcasts such as AM radio and FM radio. Car navigation devices that perform searches and the like are often installed. Many car navigation apparatuses are equipped with a receiver for receiving analog television broadcasting, one-segment broadcasting or 12-segment broadcasting (terrestrial digital television broadcasting: hereinafter referred to as DTV).

  For this reason, in recent vehicles, in addition to antennas for receiving AM radio medium waves (MW) and FM radio and TV ultra-short waves (VHF), radio waves in the ultra-high frequency (UHF) band for DTVs. Antennas that enable the reception of these have been installed. In addition, the car navigation device requires a GPS (Global Positioning System) antenna for detecting the position of the host vehicle, and the ETC (Automatic Toll Collection System), which is increasingly equipped with vehicles in recent years, also receives radio waves. An antenna is required. Therefore, many antennas are required for vehicles in recent years, and as the number of antennas increases, there is a demand for good antenna appearance without reducing the size of the antennas or the design of the vehicle.

  When these antennas are attached to an automobile, which is a moving body, the installation location of the antenna is generally a vehicle windshield. When the antenna is attached to the windshield, the antenna is formed on a transparent film sheet and attached to the windshield with an adhesive material (patented) Reference 1). Such a film antenna is often formed with a horizontally long loop antenna.

  However, since the directivity of the loop antenna for receiving the DTV attached to the upper part of the windshield is in front of the vehicle, there is a problem that reception becomes difficult when the vehicle changes its traveling direction. In order to solve this problem, the inventor of the present application devised a loop antenna having a change in directivity as shown in Patent Document 2 together with the joint inventor, and provided a minimum number of them on the top of the windshield. Thus, an inexpensive and easy-to-install vehicle antenna device with improved DTV reception directivity has been proposed.

  Here, the vehicle antenna device described in Patent Document 2 will be briefly described with reference to FIGS. 1 and 2. FIG. 1B shows a configuration of a loop antenna 10A formed on a normal transparent film 24. A rectangular shape formed on a sheet-like transparent film 24 by a conductor such as silver paste or copper foil. Antenna conductor 23, and power supply terminals 11 and 12 for supplying power to the antenna conductor 23. The power supply terminals 11 and 12 are provided close to positions symmetrical with respect to a center line that bisects the loop antenna 10A to the left and right. FIG. 2B shows the loop antenna 10A installed on the top of the windshield of the automobile and viewed from above the automobile. Reference numeral 2 denotes an automobile roof 2, and the directivity of the loop antenna 10 </ b> A faces the traveling direction F of the vehicle.

  FIG. 1C shows the configuration of the loop antenna 10B proposed in Patent Document 2, and includes a rectangular antenna conductor 23 formed of a conductor on a sheet-like transparent film 24, and an antenna conductor 23. Are provided with power supply terminals 11 and 12 for supplying power. In the loop antenna 10B, the power feeding terminals 11 and 12 are provided close to the left end with respect to a center line that bisects the loop antenna 10B to the left and right. FIG. 2C shows the loop antenna 10B installed on the top of the windshield of the automobile and viewed from above the automobile. Reference numeral 2 denotes the roof portion 2 of the automobile, and the directivity of the loop antenna 10B faces the right side R with respect to the traveling direction F of the vehicle.

  FIG. 1 (d) shows a configuration of the loop antenna 10 </ b> C proposed in Patent Document 2, and includes a rectangular antenna conductor 23 formed of a conductor on a sheet-like transparent film 24, and an antenna conductor 23. Are provided with power supply terminals 11 and 12 for supplying power. In the loop antenna 10B, the power supply terminals 11 and 12 are provided close to the right end with respect to a center line that bisects the loop antenna 10B to the left and right. FIG. 2A shows the loop antenna 10C installed on the top of the windshield of the automobile and viewed from above the automobile. Reference numeral 2 denotes the roof portion 2 of the automobile, and the directivity of the loop antenna 10C faces the left side L with respect to the traveling direction F of the vehicle.

  FIG. 1A shows a configuration of a vehicular antenna device 50 in which the loop antennas 10A to 10C described in FIGS. 1B to 1D are attached to upper left and right sides of a windshield 1 of an automobile. Yes, the windshield 1 of the automobile and its surroundings are viewed from the vehicle interior side. The antenna device 50 is for receiving DTV, and is composed of two loop antennas 10A on both ends of the windshield 1 and loop antennas 10B and 10C arranged adjacent thereto. Each of the four loop antennas 10A, 10B, and 10C is connected to a power feeding circuit including a connector 20 and a coaxial cable 22.

  Signals received by the loop antennas 10 </ b> A, 10 </ b> B, and 10 </ b> C are input to a power feeding circuit including a coaxial cable 22 through the connector 20. The coaxial cable 22 is disposed along the A-pillar 3 of the automobile and is connected to a DTV tuner (not shown). Reference numeral 8 denotes a car navigation device installed on an instrument panel 9 of an automobile, and receives an image signal from a DTV tuner.

  Accordingly, as shown in FIG. 1A, the directivity in the vertical direction of the antenna device 50 in which the loop antennas 10A, 10B, and 10C are arranged in the vicinity of the roof portion 2 on the upper portion of the windshield 1 is as shown in FIG. As shown in FIG. 2E, the horizontal directivity is obliquely upward with respect to the traveling direction F of the vehicle 60, as shown in FIG. L and right forward direction R. For this reason, even if the automobile 60 changes its traveling direction, the DTV radio wave can be received well, and the reception performance of the antenna device 50 is improved.

  In the above description, the antenna directivity indicated by the broken line indicates that the directivity is approximately in this direction, and is not an accurate directivity diagram.

JP 2006-270602 A

Japanese Patent Application No. 2007-293290

  However, the vehicle antenna device proposed in Patent Document 2 is suitable for receiving DTV radio waves arriving from the front or obliquely forward of the automobile in the traveling direction. There is a problem that reception performance is slightly difficult for reception of radio waves coming from the horizontal direction. Therefore, it is conceivable to install a monopole antenna on the windshield that does not receive incoming waves from the front and back of the car and can receive incoming waves from the top and bottom and side of the car. It was necessary to connect a ground to the body of the machine, and there was a problem that the mounting workability was poor.

  Therefore, the present invention can satisfactorily receive radio waves arriving from the left and right lateral directions with respect to the antenna installation surface, and in particular, can receive DTV broadcasts well and is inexpensive and easy to install. It is intended to provide a simple antenna, and when attached to a moving body such as an automobile with a built-in receiver, radio waves such as DTV broadcasts coming from the left and right lateral directions with respect to the traveling direction of the moving body An object of the present invention is to provide an antenna that can receive well.

  An antenna according to the present invention that achieves the above object is an antenna that receives radio waves in a predetermined frequency band, and a linear conductor having a length corresponding to one wavelength of a specific frequency in the reception frequency band. The region surrounded by is bent in an annular shape so as to be T-shaped, and both ends of the linear conductor are brought close to each other in a state where the bending of the linear conductor is completed, and both ends are used as power supply terminals. It is an antenna.

  According to the antenna of the present invention, it is possible to satisfactorily receive radio waves coming from the left and right lateral directions with respect to the antenna installation surface, and in particular, it is possible to satisfactorily receive DTV broadcasts. For this reason, when the antenna according to the present invention is attached to a moving body such as an automobile, radio waves arriving from the left and right directions of the traveling direction of the moving body can be satisfactorily received. When used in combination with a loop antenna that can receive radio waves satisfactorily, radio waves, particularly DTV radio waves, can be received satisfactorily even if the moving direction of the moving body changes, and the antenna reception performance is improved. is there.

  For example, when a loop antenna and an antenna according to the present invention are installed in a vehicle that is a moving body, the loop antenna does not receive an incoming wave from the lateral direction of the vehicle but receives an incoming wave from the longitudinal direction of the vehicle. On the contrary, the antenna according to the present invention can receive an incoming wave from the side of the vehicle. This makes it possible to provide an antenna that can ensure stable reception quality for the user.

(A) is the perspective view which looked at the windshield of the motor vehicle with which the vehicle antenna device which the present inventors proposed was attached, and its circumference from the vehicle interior side, (b) is the vehicle antenna device shown in (a) (C) is an enlarged plan view showing another loop antenna constituting the vehicular antenna device shown in (a), and (d) is an enlarged plan view showing the loop antenna constituting (a). It is a top view which expands and shows another one of the loop antennas which comprise the vehicle antenna apparatus shown by a). (A) is explanatory drawing which shows the directivity when the loop antenna shown in FIG.1 (d) is installed in the vicinity of a dielectric material, (b) is a loop antenna shown in FIG.1 (a) with a dielectric material. An explanatory diagram showing directivity when installed in the vicinity, (c) is an explanatory diagram showing directivity when the loop antenna shown in FIG. 1 (d) is installed in the vicinity of the dielectric, and (d) is Explanatory drawing which shows the directivity of the orthogonal | vertical direction when the loop antenna shown by (a) to (c) is installed in the windshield upper part of a motor vehicle, (e) is a loop antenna shown by (a) to (c) It is explanatory drawing which shows the directivity of the horizontal direction of each antenna at the time of being installed in the windshield upper part of a motor vehicle. (A) is explanatory drawing which shows the relationship between the length of the linear conductor which comprises the antenna based on this invention, and one wavelength of a received radio wave, (b) is the book formed by bending the linear conductor shown to (a) It is explanatory drawing which shows the connection of the antenna which concerns on invention, and the receiver of this antenna. FIG. 4 is an explanatory diagram showing a relationship between a region formed by a linear conductor and a power feeding terminal to the antenna in the antenna according to the present invention shown in FIG. (A)-(f) is a block diagram which shows the 1st-6th Example which shows the installation position of the electric power feeding terminal in the antenna which concerns on this invention. (A) is explanatory drawing which shows the Example which shifted the 2nd area | region of the antenna with respect to the 1st area | region with respect to the installation position of the feed terminal in the antenna which concerns on this invention, (b) is the antenna which concerns on this invention It is explanatory drawing which shows the Example which shifted the 2nd area | region of the antenna in another direction with respect to the 1st area | region with respect to the installation position of the electric power feeding terminal. (A) is a top view of the Example which shows the specific structure of the antenna based on this invention, (b) is sectional drawing in the BB line of (a). It is explanatory drawing which shows the directivity when the antenna which concerns on this invention shown to Fig.7 (a) is installed in the vicinity of a dielectric material. (A) is a perspective view which shows an example of the connector connected to the electric power feeding terminal of the antenna which concerns on this invention, and the external appearance of the coaxial cable connected to this, (b) is a disassembled perspective view of the connector shown to (a). FIG. 9A is a diagram of an example of the circuit board shown in FIG. 9B viewed from the back side, and FIG. 9B is an example of the internal configuration of the amplifier mounted on the circuit board shown in FIG. Block circuit diagram, (c) is a block circuit diagram showing another embodiment of the internal configuration of the amplifier mounted on the circuit board shown in (a). (A)-(d) is the figure which looked at the state which attached the antenna which concerns on this invention to the upper end part of the windshield of a motor vehicle from the vehicle interior side, (a) is only one antenna attached. (B) is a diagram showing an embodiment in which an antenna is attached in combination with a loop antenna, (c) is a diagram showing an embodiment in which two antennas are attached in combination, (D) is a figure which shows the Example with which four antennas were combined and attached.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an antenna according to the present invention will be described below in detail with reference to the accompanying drawings based on specific examples in which an antenna is installed on a windshield of an automobile. In addition, the same code | symbol is attached | subjected and demonstrated about the same structural member demonstrated in FIG. 1, FIG.

  FIG. 3 (a) shows the relationship between the length of the linear conductor 51 constituting the antenna according to the present invention and one wavelength λ of the received radio wave. In the present invention, a linear conductor 51 having a length corresponding to one wavelength λ of a radio wave having a specific frequency f in a frequency band desired to be received by an antenna is prepared. The specific frequency f may not be the center frequency fc of the frequency band to be received. Note that the length of the linear conductor 51 is not necessarily equal to one wavelength λ of the radio wave propagating in free space, and is best described when the antenna constituted by the linear conductor 51 is installed in the dielectric portion of the vehicle. For the sake of convenience, the length of the linear conductor 51 that receives a radio wave of one wavelength λ is also described as λ.

  In the present invention, the linear conductor 51 shown in FIG. 3A is bent, and the region surrounded by the linear conductor 51 is formed in a T shape as shown in FIG. Form. At this time, terminals 53 and 54 are provided at both ends of the linear conductor 51, and when the linear conductor 51 is bent, the terminals 53 and 54 are brought close to each other to serve as power supply terminals. When the connector 20 is connected to the power supply terminals 53 and 54 and the connector 20 is connected to the receiving device 52 with the coaxial cable 22, the vehicle antenna device 50 is obtained.

  FIG. 4 shows the relationship between the region formed by the linear conductor 51 and the feed terminals 53 and 54 in the antenna 55 according to the present invention shown in FIG. When the linear conductor 51 is bent so that the region surrounded by the linear conductor 51 is T-shaped, the T-shaped region includes a first region H corresponding to a T-shaped horizontal bar, and a T-shape. There is a second region V corresponding to the vertical bar. In the antenna 55 according to the present invention, the length L in the longitudinal direction of the second region V is set to ¼ of the wavelength λ in order to satisfactorily receive the radio wave having the wavelength λ. Further, even when the length (Y + L) from the upper side of the first region H to the lower side of the second region V is set to ¼ of the wavelength λ, radio waves having the wavelength λ can be received well. .

  It should be noted that when the antenna 55 is installed on the windshield of the automobile, the size of the antenna 55 can be reduced so as not to obstruct the driver's view or to impair the automobile design. is there. Even if the length L and the length (Y + L) are not exactly ¼ of the wavelength λ of the desired reception frequency, if the length is close to that, the radio wave of the wavelength λ can be received well. This is because a product with higher added value can be provided to the user.

  Incidentally, as a result of the experiment, the width Y of the parallel linear conductors 51 constituting the first region H is set to 1/40 of the wavelength λ, and the parallel linear conductors 51 constituting the second region V are It was found that if the width X is 1/20 of the wavelength λ, the reception sensitivity is good. It was also found that the reception sensitivity is good if the power supply terminals 53 and 54 are provided in the vicinity of the portion (connection portion) C where the first region H and the second region V are in contact.

  FIGS. 5A to 5F show first to sixth embodiments showing preferred installation positions of the feeding terminals 53 and 54 in the antenna 55 according to the present invention. In the first embodiment shown in FIG. 5A, the power supply terminals 53 and 54 are at the bottom of the first region H on the left side of the second region V. In the second embodiment shown in FIG. 5B, the power supply terminals 53 and 54 are at the bottom of the first region H on the right side of the second region V. In the third embodiment shown in FIG. 5C, the power supply terminals 53 and 54 are on the left side portion of the second region V. In the fourth embodiment shown in FIG. 5 (d), the power supply terminals 53 and 54 are on the right side of the second region V. In the fifth embodiment shown in FIG. 5E, the power supply terminals 53 and 54 are respectively provided on the bottom side of the first area H on the left side of the second area V and on the side side on the left side of the second area V. is there. In the sixth embodiment shown in FIG. 5 (f), the power supply terminals 53 and 54 are respectively provided on the bottom side of the first region H on the right side of the second region V and on the side side on the right side of the second region V. is there.

  By the way, when the power supply terminals 53 and 54 are located at the bottom of the first region H on the left side of the second region V as in the first embodiment shown in FIG. Due to the presence of 54, the left and right balance of the first region H becomes poor. That is, the power supply terminals 53 and 54 are ideally points, but it is necessary to form a land pattern for connection with the connector, and the power supply point is shifted in either the left or right direction. Therefore, in the case of the first embodiment, as shown in FIG. 6A, the second region V is shifted to the right with respect to the center line CH that divides the first region H into two. Balance. That is, the center line CV in the longitudinal direction of the second region V is shifted to the right with respect to the center line CH.

  For example, when the length D1 shown in FIG. 6A is 50 mm, the second region V is placed on the right side with respect to the first region H so that the length D2 is 55 mm and the length D3 is 45 mm. shift. As a result, radio waves coming from the left and right directions of the second region V can be received with a good balance. In this case, if the length L is 65 mm, the length X is 20 mm, and the length Y is 10 mm, the antenna 55 has good sensitivity. Further, the maximum shift amount of the second region V is about 30 mm.

  FIG. 6B shows a case where the power supply terminals 53 and 54 are at the bottom of the first region H on the right side of the second region V as in the second embodiment shown in FIG. An example is shown. In the case of the second embodiment, the second region V may be shifted to the left with respect to the center line CH that divides the first region H into left and right. Since the dimensional relationship in the shift is the same as in FIG. 6A, the same reference numerals are given to the same dimensions, and the description thereof is omitted.

  FIG. 7A is an embodiment showing a specific configuration of the antenna 55 according to the present invention, and FIG. 7B shows a cross section taken along line BB of FIG. 7A. The antenna 55 includes a linear conductor 51 having a line width of about 0.3 mm and formed in a hollow T shape, and rectangular power supply terminals 53 and 54 connected to both ends of the linear conductor 51. These are formed of a conductive material on a transparent base film 17. A linear conductor 51 made of a conductor such as silver paste or copper foil and a transparent protective layer 4 for protecting the linear conductor 51 are provided on the upper surface side of the base film 17, and an adhesive material (adhesive strength) is provided on the lower surface side. (Weak adhesive) 5 is applied. This adhesive material 5 is covered with a separator 6 that can be peeled off from the adhesive material surface. The antenna 55 is attached to the windshield by peeling off the separator 6 to expose the adhesive 5 and attaching the adhesive 5 to the inside of the windshield of the automobile.

  FIG. 8 shows the directivity when the antenna 55 according to the present invention shown in FIG. 7A is arranged in the vicinity of the roof portion 2 on the upper part of the windshield 1 of the automobile. The directivity of the antenna 55 is the left-right direction with respect to the traveling direction F of the automobile. For this reason, the automobile can satisfactorily receive DTV radio waves coming from both sides thereof. The directivity of the antenna 55 indicated by a broken line in FIG. 7A indicates that the directivity is approximately in this direction, and is not an accurate directivity diagram.

  FIGS. 9A and 9B show the appearance of the connector 20 and a state where the connector 20 is disassembled. As shown in FIG. 9A, the connector 20 is configured by combining an inner case 21 and an outer case 25, and two openings are formed on the surface of the inner case 21 (the mounting surface to the connection terminals 53 and 54). There are portions 21A and 21B, and connecting terminals 31 and 32 having spring properties protrude from the openings 21A and 21B. The surface of the inner case 21 of the connector 20 is affixed on the antenna with an adhesive or adhesive such as double-sided tape, and the connection terminals 31 and 32 are connected to the connection terminals 53 and 54.

  As shown in FIG. 9B, the connection terminals 31 and 32 are attached on one surface of a circuit board (dielectric substrate) 30 built in the inner case 21 and the outer case 25. A coaxial cable 22 is connected to 30. The circuit board 30 has a notch 35 for receiving the covering portion of the coaxial cable 22, and the inner case 21 and the outer case 25 have a curved recess 26 for receiving the covering portion of the coaxial cable 22. An integrated circuit 40 described later is mounted on the other surface of the circuit board 30. Generally, the connection terminal 31 is a hot side (signal transmission side) terminal, and the connection terminal 32 is a ground side terminal.

  FIG. 10A shows a general configuration of the circuit board 30 inside the connector 20 shown in FIG. 9B except for the inner case 21 and the outer case 25. The connection terminals 31 and 32 are attached to the back side of the circuit board 30 and led to the front side of the circuit board 30 through the through holes 33 and 34. In this example, the through hole 33 is connected to the input terminal of the integrated circuit 40 mounted on the front side of the circuit board 30, and the through hole 34 is connected to the ground wire (outer conductor) 22 </ b> B of the coaxial cable 22. The integrated circuit 40 performs processing such as amplification on the signal received by the antenna, and the processed signal is output to the central conductor (inner conductor) 22 </ b> A of the coaxial cable 22.

  FIG. 10B shows an example of the internal configuration of the integrated circuit 40 shown in FIG. Inside the integrated circuit 40, there are a matching circuit and filter 41 connected to the antenna 10, an amplifier 42 that amplifies a signal output from the matching circuit and filter 41, and a filter 43 that determines a signal band output from the amplifier 42. The filter 43 is connected to the central conductor 22A of the coaxial cable 22 through a capacitor 44 that blocks direct current. The coaxial cable 22 is a power superimposed cable, and the superimposed power supply voltage (direct current) is supplied to the amplifier 42 through a coil 45 that cuts off an alternating current component.

  FIG. 10C shows another example of the internal configuration of the integrated circuit 40 shown in FIG. This circuit is different from the circuit shown in FIG. 10B in that a balun 46 connected to the connection terminals 31 and 32 is provided. One of the two output terminals of the balun 46 is connected to the matching circuit and the filter 41, and the other is grounded. Other configurations are the same as those of the circuit of FIG. 10B, and thus further description is omitted.

  11 (a) to 11 (d) show an embodiment in which the antenna 55 according to the present invention is attached to the upper end of the windshield 1 of an automobile alone or in combination with a loop antenna. Is viewed from the passenger compartment side. FIG. 11A shows an embodiment in which only one antenna 55 is attached. FIG. 11B shows an embodiment in which two antennas 55 are attached in combination with two loop antennas 10. The directivity of the antenna 55 is the left-right direction of the automobile, whereas the directivity of the loop antenna 10 is the front of the automobile. Note that the antenna 55 and the loop antenna 10 may be opened by about 10 mm.

  In the case of the conventional rectangular loop antenna 10, when installed on the upper end portion (a portion adjacent to the roof portion) of the windshield 1, the metal roof portion reflects the broadcast wave, so the directivity is the longitudinal direction of the automobile. I could only secure it. However, the antenna 55 according to the present invention is a T-shaped loop antenna, and if such an antenna is installed at the upper end of the windshield 1, the directivity in the left-right direction (lateral direction) of the automobile can be secured. become.

  As a result, until now, only the loop antenna 10 installed on the windshield 1 of the automobile has been able to obtain only the directivity in the front-rear direction of the automobile, but the antenna 55 according to the present invention is installed on the upper end of the windshield 1. As a result, the directivity in the left-right direction of the automobile can be secured, the degree of freedom in designing the antenna is improved, and more stable broadcast radio wave reception performance can be secured. This makes it possible to provide users with an antenna that does not sacrifice the design of the automobile.

  On the other hand, FIG. 11C shows an embodiment in which two antennas 55 are combined and attached. However, since the antenna 55 attached to the upper left portion of the windshield 1 has the first region H attached in parallel to the upper end portion of the windshield 1, the directivity is the left-right direction of the automobile. On the other hand, the antenna 55 attached to the upper right portion of the windshield 1 has the first region H attached in the vertical direction with respect to the upper end portion of the windshield 1, so that the directivity is the front-rear direction of the automobile. is there.

  In general, the windshield of an automobile is often inclined with respect to the ground at an angle of 45 ° or less, and the first region H of the antenna 55 is perpendicular to the upper end of such a windshield. This is because when the antenna 55 is attached, the directivity of the antenna 55 is the front-rear direction of the automobile.

  FIG. 11 (d) shows an embodiment in which four antennas 55 are combined and attached. In this embodiment, an antenna 55 in which a first region H is attached in parallel to the upper end portion of the windshield 1 on the left and right upper portions of the windshield 1, and the first region H is connected to the upper end portion of the windshield 1. The antennas 55 mounted in the vertical direction are respectively combined and arranged. As a result, in the arrangement of FIG. 11D, it is possible to receive both radio waves coming from the front-rear direction and the left-right direction of the vehicle.

  In the case where a plurality of antennas are installed on the windshield, a diversity device that extracts and outputs a highly sensitive signal received from the plurality of antennas may be installed. Moreover, although the example which forms an antenna on a transparent film was demonstrated in the above-mentioned Example, the antenna which concerns on this invention can also be directly embedded in the window glass of a motor vehicle, and can be formed.

  In the embodiment described above, the antenna installation location is described as a windshield of an automobile, but the antenna according to the present invention is a window glass or exterior member other than a windshield such as a rear glass of an automobile, a vehicle other than an automobile, Or it is applicable also to a portable type portable electronic device. Moreover, the antenna according to the present invention can be applied not only to a moving body such as an automobile but also to a compact antenna device that can ensure the directivity in the front-rear direction and the lateral direction.

DESCRIPTION OF SYMBOLS 1 Windshield 2 Roof part 5 Adhesive material 10 Loop antenna 17 Base film 20 Connector 31, 32 Connection terminal 51 Linear conductor 53, 54 Feeding terminal 55 Antenna according to the present invention H First region V Second region

Claims (5)

An antenna that receives radio waves in a predetermined frequency band,
Bending a linear conductor having a length corresponding to one wavelength of a specific frequency in the reception frequency band into an annular shape so that a region surrounded by the linear conductor is T-shaped;
Both ends of the linear conductor are brought close to each other in a state where the bending of the linear conductor is completed,
An antenna characterized in that the both ends are feed terminals. Of the T-shaped region surrounded by the linear conductor, the region corresponding to the T-shaped horizontal bar is the first region, and the region corresponding to the T-shaped vertical bar is the second region,
2. The antenna according to claim 1, wherein a length of the second region in a longitudinal direction is a length corresponding to a quarter of one wavelength of the specific frequency.   The antenna according to claim 2, wherein the feeding terminal is provided in the vicinity of a portion where the first region and the second region are in contact with each other.   The second region is in contact with the first region so that the center line in the longitudinal direction passes through a position offset by a predetermined distance with respect to the midpoint in the longitudinal direction of the first region. The antenna according to claim 2 or 3, wherein   5. The antenna according to claim 1, wherein the antenna is attached to an upper portion of a window glass of a vehicle so that a longitudinal direction of the first region is parallel to an edge of the window glass. The antenna according to item.

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