JP4278589B2 - antenna - Google Patents

Description

The present invention relates to antennas, particularly, in a mobile such as an automobile, about the antenna that is used by being attached to the moving body without impairing the design of the moving body.

  2. Description of the Related Art Conventionally, an antenna that enables reception of radio waves while moving is mounted on a vehicle (moving body) such as an automobile. In general, radio waves received by vehicles have been mainly AM radio wave (MW), FM radio and TV ultra-high frequency (VHF) and ultra-high frequency (UHF) for many years.

  However, in recent years, in addition to antennas that receive these radio waves, high-frequency GPS (Global Positioning System) antennas, or satellite radio waves for satellite digital broadcasting and their re-radiated waves (gap filler) An antenna that receives radio waves) and an antenna that transmits and receives radio waves for telephones such as car phones and mobile phones are becoming necessary for vehicles. As part of ITS (Intelligent Transport System), ETC (Automatic Tollgate System) that automatically collects tolls for expressways and toll roads and VICS (Road Traffic Information Communication System) that provides road traffic information. An antenna for transmitting and receiving radio waves is also required for radio beacons. Furthermore, antennas such as a keyless entry system for remotely controlling locking / unlocking of a vehicle door, a vehicle anti-theft device, and a remote engine starting device for remotely controlling engine starting have become necessary for the vehicle. Therefore, recent vehicles have to be equipped with antennas for receiving or transmitting many types of radio waves.

  Among such radio waves to be transmitted or received by such a moving body, circularly polarized waves are used for GPS radio waves, satellite digital broadcast satellite radio waves, or ETC radio waves. Many patch antennas have been used for conventional circularly polarized antennas. As this patch antenna, a configuration is often adopted in which a planar ground conductor is installed on one surface of a dielectric substrate such as ceramic and a radiation conductor is installed on the other surface. As this type of patch antenna, a low-profile, horizontally omnidirectional patch antenna that has been proposed for use on a roof of a movable body such as an automobile has already been proposed (see, for example, Patent Document 1). ).

Japanese Patent Laid-Open No. 2002-135045 (FIGS. 1 and 2)

  However, since the patch antenna disclosed in Patent Document 1 and the like uses a substrate, the thickness of the antenna becomes large, and it is difficult to reduce the thickness, which may impair the design of the vehicle. In addition, when the patch antenna is installed on a windshield or the like without being installed on the roof of the vehicle, the patch antenna needs to be provided with a substrate having a certain area or more and a planar ground conductor. There was also a problem that impaired the field of view.

  For such problems, as a circularly polarized antenna that does not impair the forward field of view, a circularly polarized antenna configured with a linear conductor, such as a helical antenna or a crossed dipole antenna, has also been proposed, This proposed antenna has a problem that the height of the antenna is increased and a phase shifter, a signal synthesizer or a signal distributor is required, resulting in an increase in cost.

Therefore, the present invention arranges the linear conductors constituting the antenna so as to form one surface, thereby enabling the antenna to be thinned and mounted inside the vehicle, eliminating the possibility of impairing the vehicle design. , no portions of the antenna obstructs the view, further, a feed structure is simple, and its object is to provide an antenna which can mainly be satisfactorily transmit and / or receive circularly polarized waves.

Another object of the present invention, by incorporating as much of the thin antenna can other antennas that need to be mounted on a vehicle, reducing antenna mounting space, to provide a antenna with a reduced cost of the antenna It is in.

Antenna of the present invention to achieve the object may take the following first and second embodiments.

The first form includes a loop antenna and a parasitic element that is arranged in the vicinity of the loop antenna and is configured of an independent conductor with respect to the loop antenna. The parasitic element is viewed from the feeding point of the loop antenna. A first portion disposed adjacent to the antenna conductor constituting the loop antenna, and a first portion disposed near the antenna conductor constituting the loop antenna. The second part of the parasitic element is configured to be parallel to a straight line connecting the counter electrode of the loop as viewed from the feeding point of the loop antenna. The loop antenna is a substantially square antenna conductor, which has a feeding point at one vertex of a square of the antenna conductor, and a vertex having a rectangular feeding point of the antenna conductor as the top. In this case, the first part of the parasitic element is arranged in parallel with or close to the lower right and / or upper left side of the antenna conductor, and the loop antenna has two ends, one end Is an antenna characterized by receiving radio waves and grounding the other end .

The second form includes a loop antenna and a parasitic element that is arranged in the vicinity of the loop antenna and is composed of an independent conductor with respect to the loop antenna. The parasitic element is viewed from the feeding point of the loop antenna. A first portion disposed adjacent to the antenna conductor constituting the loop antenna, and a first portion disposed near the antenna conductor constituting the loop antenna. The second part of the parasitic element is configured to be parallel to a straight line connecting the counter electrode of the loop as viewed from the feeding point of the loop antenna. The loop antenna is a substantially rectangular antenna conductor, and the antenna conductor is provided with a feeding point at one vertex of the square, and the vertex with the rectangular feeding point of the antenna conductor is turned up. In this case, the first portion of the parasitic element is arranged in parallel with or near to the upper right and / or lower left sides of the antenna conductor, the loop antenna has two ends, and one end is An antenna is characterized by receiving radio waves and grounding the other end .

According to the present invention, the feed structure is simple, antenna is provided that can transmit and / or receive circularly polarized waves. In addition, various antennas can be installed on thin dielectrics, and can also be installed on vehicle dielectrics, so there is no risk of damaging the vehicle design, and the antennas are damaged or stolen. There is an effect that there is no fear of. Further, by using a thin dielectric as a transparent film, there is an effect that there is no possibility of obstructing the driver's view. Furthermore, by incorporating as many other antennas that need to be mounted on the vehicle as possible into this thin antenna, the space for mounting multiple types of antennas for radio waves can be reduced and cables can be integrated. This improves the mountability and mountability of the antenna and reduces the antenna installation cost.

  Embodiments according to the present invention will be described below in detail based on specific examples with reference to the accompanying drawings. In general, an antenna can perform both transmission and reception of radio waves. However, in the following embodiment, only the case where the antenna receives radio waves will be described for the sake of simplicity. Description of the case of transmitting radio waves is omitted. It goes without saying that transmission of radio waves from an antenna is included in the present invention.

  FIG. 1 shows a thin antenna 10 according to a first embodiment of the present invention and two cables 2 and 3 connected thereto. The antenna 10 of the first embodiment includes a loop antenna 12 for transmitting and / or receiving circular polarization (hereinafter referred to as transmission / reception) and two TV antennas for receiving TV radio waves on a transparent film 11. 13 and 73. FIG. 1 shows the thin antenna 10 as viewed from the direction opposite to the direction of arrival of radio waves. That is, when the thin antenna 10 is attached to, for example, the inside of a windshield of an automobile, this is viewed from the interior side of the automobile. The loop antenna 12 viewed from the vehicle interior side is disposed on the left side of the transparent film 11. Since the loop antenna 12 transmits and receives right-handed circularly polarized waves, a parasitic element 14 which will be described in detail later is provided outside the antenna conductor constituting the loop antenna 12.

  Moreover, the TV antennas 13 and 73 are provided along the periphery of the transparent film 11, and the tip portions of the TV antennas 13 and 73 are bent. In this embodiment, a portion of the transparent film 11 where the loop antenna 12 and the TV antennas 13 and 73 are not provided is cut out to form a hole 15. The hole 15 is provided so as to surround a portion of the transparent film 11A on which the loop antenna 12 is disposed, and a portion of the transparent film 11A on which the loop antenna 11 is disposed has a tongue-like shape. Hereinafter, this portion is referred to as a tongue portion 11A of the transparent film. Furthermore, two feeding terminals 16 and 17 are provided at both ends of the antenna conductor constituting the loop antenna 12, and an antenna connection terminal is provided at one end of the linear conductor constituting the TV antennas 13 and 73. 18, 79 are provided. In this embodiment, the antenna connection terminals 18 and 79 are provided at the upper left portion of the transparent film 11 and are provided on both sides of the power supply terminals 16 and 17 of the loop antenna 12. Furthermore, the loop antenna 12, the parasitic element 14, the TV antennas 13 and 73, and the antenna connection terminals 18 and 79 may be formed by printing with the same conductor thin film, wire, conductive ink, or conductor such as copper foil. .

  The cable 2 can be connected to the two power supply terminals 16 and 17 of the loop antenna 12, and radio waves received by the loop antenna 12 are guided to a predetermined receiver, for example, a GPS receiver, by the cable 2. A connector 21 is connected to a distal end portion of the cable 2 on the thin antenna 10 side, and two connection terminals 22 and 23 provided on the connector 21 are connected to two feeding terminals 16 and 17 of the loop antenna 12, respectively. . The two connection terminals 22 and 23 have springiness in this embodiment. The connector 21 may be adhered to the transparent film 11 with, for example, a double-sided adhesive tape. Since the cable 2 is a coaxial cable, in this embodiment, one of the feeding terminals 16 and 17 is grounded. In addition, an amplifier and a balance circuit (balance-unbalance conversion circuit) described later can be mounted inside the connector 21.

  The cable 3 can be connected to the antenna connection terminals 18 and 79 of the TV antennas 13 and 73, respectively. Radio waves received by the TV antennas 13 and 73 are guided to a TV tuner (selector) (not shown) by the cable 3 and the cable 4 connected thereto. Since the cables connected to the antenna connection terminals 18 and 79 have the same configuration, the cables 3 and 4 connected to the antenna connection terminal 79 are not shown. A connector 31 is connected to the distal end portion of the cable 3 on the thin antenna 10 side, and a connection terminal 32 provided on the connector 31 is connected to the antenna connection terminal 18 of the TV antenna 13. For example, the connector 31 may be bonded to the transparent film 11 with a double-sided adhesive tape. The cable 3 is a single-core cable, and is connected to the core wire 41 of the coaxial cable 4 in this embodiment. The ground wire 42 of the coaxial cable 4 is guided to a part of a vehicle body 44 by another single-core cable 43 and is connected to a metal foil 45 attached to the body 44 by a connector 46. In other words, the ground wire 42 of the coaxial cable 4 is AC-grounded to the body 44 of the automobile.

  FIG. 2A shows the configuration of a thin TV antenna 50 used with the thin antenna 10 of the present invention. The TV antenna 50 includes two TV antennas 51 and 52 for receiving TV radio waves on the transparent film 11. FIG. 2A shows the television antenna 50 viewed from the interior side of the automobile when the television antenna 50 is installed inside the windshield of the automobile. The two TV antennas 51 and 52 viewed from the vehicle interior side are provided along the periphery of the transparent film 11. In this embodiment, the transparent film 11 in a portion where the two TV antennas 51 and 52 are not provided is provided. The hole 55 is cut out. Furthermore, antenna connection terminals 53 and 54 are provided at one end portions of the linear conductors constituting the TV antennas 51 and 52, respectively. A cable similar to the cable 3 described in FIG. 1 is connected to the antenna connection terminals 53 and 54 via a connector, and the received radio wave is similarly guided to the TV tuner (selector) through the cable.

  FIG. 2 (b) shows the connection of the automobile with the receiver 8 when the thin antenna 10 of FIG. 1 and the thin TV antenna 50 of FIG. 2 (a) are installed on the left and right upper parts of the windshield 1 of the automobile. It shows the front of the passenger compartment. In an automobile, the receiver 8 is often a navigation device, and hence the receiver 8 will be described as the navigation device 8 hereinafter. In recent years, the navigation device 8 has many functions such as a TV screen display, music playback and image playback, traffic information display, etc., in addition to a navigation function that displays the current position of a car on a map and indicates a route to a destination. It has. FIG. 3 is a circuit diagram showing connections between the thin antenna 10, the thin TV antenna 50, and the navigation device 8 shown in FIG.

  First, the connection of the thin antenna 10 and the thin TV antenna 50 to the navigation device 8 will be described with reference to FIG. The loop antenna 12 provided in the thin antenna 10 is connected to the GPS receiver 81 built in the navigation device 8 using the connector 21 and the coaxial cable 2 as described above. In this embodiment, an amplifier 6 is built in the connector 21, and a signal obtained by receiving radio waves with the loop antenna 12 is amplified by the amplifier 6 and output.

  The two TV antennas 13 and 73 provided in the thin antenna 10 are connected to the selector 47 of the selector / amplifier 40 by the connector 31, the cable 2 (not shown), and the coaxial cable 4, respectively. Further, the two TV antennas 51 and 52 provided on the thin TV antenna 50 are connected to the selector 47 of the selector / amplifier 40 by the connector 31, the cable 2 (not shown), and the coaxial cable 4, respectively. The selector 47 selects a TV antenna (any one of the TV antennas 13, 73, 51, 52) with high reception sensitivity and switches the TV antenna so that the output is output to the amplifier 48. As a result, any of the TV antennas 13, 73, 51, 52 is connected to the TV tuner 82 built in the receiver 8 through the selector / amplifier 40 and the coaxial cable 5. Each of the TV antennas 13, 73, 51, 52 can receive TV broadcast waves and FM broadcast waves.

  In the navigation device 8, in addition to the GPS receiver 81 and the TV tuner 82, a storage medium 83 composed of a CD, DVD, HDD or the like that stores map information, and a liquid crystal display that displays a map or a TV screen. There is a display 84 and a controller 85 for calculating the current position of the vehicle, route guidance, etc., and they are connected to each other via an internal bus 86. The TV tuner 82 and the liquid crystal display 84 may be provided integrally with the navigation device 8, but may be provided separately. The selector / amplifier 40 may be built in the navigation device 8.

  When the navigation device 8 is in the navigation mode, the controller 85 calculates the current position of the vehicle based on signals from the GPS satellites received by the loop antenna 12 and the GPS receiver 81, and displays a map corresponding to the current position as map information. The map read out from the storage medium 83 is displayed on the liquid crystal display 84, and the current position of the automobile is displayed on the map. In addition, when the destination is input, the controller 85 can calculate a route from the current position to the destination and display it on the map. Further, when the navigation device 8 is in the television mode, the controller 85 receives a TV broadcast by any one of the TV antennas 13, 17, 51, 52 and the TV tuner 82, and displays the received TV broadcast on the liquid crystal display 84.

  Returning to FIG. 2B, in this embodiment, the navigation device 8 is built in the center console of the automobile, and the selector / amplifier 40 is built in the foot on the passenger seat side. The cables 2 and 4 from the thin antenna 10 and the thin TV antenna 50 are attached along the A-pillar of the automobile and directly connected to the navigation device 8, or the receiver 8 through the selector / amplifier 40 and the cable 5. Connected to. Since the thin antenna 10 and the thin TV antenna 50 are configured using the transparent film as described above, the thin antenna 10 and the thin TV antenna 50 are provided even when they are attached to the top of the windshield 1. And will not interfere with the field of view of the driver of the car, in particular, the field of vision V in the left front. Further, by attaching the thin antenna 10 to the front passenger seat side of the windshield 1 as in this embodiment, the loop antenna 12 is less likely to enter the driver's field of view, and the vehicle driver's field of view is not easily obstructed.

  A sectional view taken along line AA of the loop antenna 12 provided in the thin antenna 10 shown in FIG. 1 is shown in FIG. Reference numeral 19 in the figure is a protective film. The thin antenna 10 can be affixed to the back surface (vehicle interior side) of the automobile windshield 1 shown in FIG. 2B by a double-sided adhesive tape 39 affixed to the surface opposite to the protective film 19. As another embodiment, the loop antenna 12 can be provided on one surface of the transparent film 11, and the parasitic element 14 can be provided on the other surface of the transparent film 11. This embodiment is shown in FIG. In this embodiment, the protective film 19 is laminated on both surfaces of the transparent film 11, and the double-sided adhesive tape 39 is attached to the surface on the side where the parasitic element 14 is present. Thus, the parasitic element 14 is effective as long as it is close to the antenna conductor even if it is not on the same plane as the antenna conductor of the loop antenna 12. Although not shown, the protective film 19 may be provided so as to cover the loop antenna 12 and the parasitic element 14, and may not be provided so as to cover the entire transparent film 11. Furthermore, the loop antenna 12 and the parasitic element 14 may be provided on one surface, and the TV antennas 13 and 73 may be provided on the other surface.

  As yet another embodiment, the thin antenna 10 and the thin TV antenna 50 can be incorporated in the windshield 1 of an automobile. An example thereof is shown in FIG. FIG. 17C is a partial cross-sectional view of the windshield 1 of the automobile at the same site as FIG. Although not shown, the thin antenna 10 and the thin TV antenna 50 may be provided on the surface or inside of an automobile exterior member made of an insulator.

  FIG. 4A shows a form in which an amplifier (low noise amplifier) 6 is built in the connector 21 connected to the loop antenna 12 shown in FIG. With this configuration, the radio wave received by the loop antenna 12 can be amplified by the amplifier 6 and guided to the GPS receiver by the coaxial cable 2. FIG. 4B is a circuit diagram showing an example of the internal configuration of the amplifier 6 shown in FIG. In this figure, C is a capacitor, L is a coil, 24 and 26 are amplifiers, and 25 is a band pass filter (BPF). When the loop antenna 12 receives radio waves used for GPS, the center frequency of the BPF 25 is 1575 MHz, and the band is 1.5 MHz up and down with this frequency as the center.

  FIG. 5A shows that the connector 21 connected to the loop antenna 12 shown in FIG. 1 includes the balance circuit (balanced-unbalanced conversion circuit, indicated as balun in the figure) 7 and the amplifier 6. FIGS. 5B and 5C show two examples that can be used for the balance circuit 7 of FIG. FIG. 5B shows an example of a bridge-type balance circuit 7, and FIG. 5C shows an example of a ladder-type balance circuit 7. Since these circuits are known, further explanation will be given. Is omitted.

  Here, the configuration in the present invention of the loop antenna 12 that receives the circularly polarized wave mainly received by the thin antenna 10 of the present invention will be described.

  FIG. 6A shows the configuration of a circularly polarized loop antenna 12 for right-handed circular polarization, out of the circularly polarized loop antenna 12 used in the present invention. The right-handed circularly polarized wave is used for ETC radio waves in addition to GPS radio waves. This figure shows a state in which the loop antenna 12 is viewed from the direction of arrival of the right-handed circularly polarized wave. In the figure, reference numerals 16 and 17 denote power supply terminals to which a power supply circuit or a coaxial cable is connected, and an antenna conductor is connected to the power supply terminals 16 and 17 via a connecting conductor 27. Reference numeral 14 denotes an independent linear conductor that is not connected to the loop antenna 12, and is disposed outside the loop antenna 12. In the present invention, this linear conductor is called a parasitic element.

  The shape of the antenna conductor of the loop antenna 12 of this embodiment is square, and feed terminals 16 and 17 are provided at one apex thereof. In this embodiment, the parasitic element 14 includes a first portion 14A that is a linear conductor parallel to one side of the antenna conductor, and a linear second portion that is electrically connected to the first portion 14A. 14B. The second portion 14B is disposed at a predetermined angle with respect to the virtual extension line IE of the first portion 14A. Hereinafter, this state is said that the second portion 14B is bent with respect to the first portion. The bending direction of the second portion 14B is bent toward the antenna conductor side, that is, the side where the other side of the antenna conductor is present with respect to the virtual extension line IE of the first portion 14A. The second portion 14B gradually moves away from the antenna conductor of the loop antenna 12 that is closer to the free end side. The second portion 14B of this embodiment is arranged in parallel to a straight line CL that connects the midpoint of the power supply terminals 16 and 17 and the apex opposite to the intermediate point. In this embodiment, the power supply terminal 17 of the power supply terminals 16 and 17 is grounded.

  Here, the function of the parasitic element 14 will be described. Considering the loop antenna 12 without the parasitic element 14, in particular, when the loop antenna 12 having the circumference (the total length of the antenna conductor) of 1 wavelength is attached to the automobile, it is perpendicular to the automobile. Only the electric field component (transverse component) is received. This is not related to the shape of the antenna conductor of the loop antenna 12. On the other hand, in the case of circularly polarized waves, the direction of the electric field changes with time, and the circularly polarized waves cannot be completely received unless the changing circularly polarized waves are always received. The parasitic element 14 is provided close to the antenna conductor of the loop antenna 12 in order to receive the longitudinal component of this circularly polarized wave. More precisely, the longitudinal component of the circularly polarized wave is taken in by the second portion 14B of the parasitic element 14, and the longitudinal component of the circularly polarized wave received by the first portion 14A in the vicinity of the antenna conductor is transformed into the adjacent loop. It is coupled to the antenna conductor of the antenna 12. As a result, the vertical component and the horizontal component of the circularly polarized wave are received by the loop antenna 12 in the same phase. That is, if the parasitic element 14 is only the second portion 14B, the received circularly polarized wave is difficult to be transmitted to the loop antenna 12. Therefore, in order to efficiently transmit the received circularly polarized wave to the loop antenna 12, the parasitic element 14 is provided with a first portion 14A.

  The total length of the antenna conductor constituting the loop antenna 12 is formed to be equal to the wavelength of radio waves to be transmitted and received. In the case of GPS, the length of one side of the antenna conductor is 48 mm. In addition, the total length of the conductor constituting the parasitic element 14 (the total value of the length of the first portion and the length of the second portion) is about ½ wavelength of the radio wave transmitted and received by the loop antenna 12 in this embodiment. The length is about 90 mm. The total length of the conductor constituting the parasitic element 14 may be longer than about ½ wavelength of the radio wave transmitted / received by the loop antenna 12 and may be an integral multiple of the wavelength of the radio wave transmitted / received by the loop antenna 12. Is possible.

  This embodiment is a case where a loop antenna is installed on a dielectric having a relative dielectric constant of 1. When this loop antenna is installed on a member having a high dielectric constant such as glass, the loop is shortened according to the shortening of the wavelength. What is necessary is to reduce the size of the antenna.

  For example, let λ1 be the wavelength of a radio wave at a specific frequency on the dielectric, λ0 be the wavelength of the radio wave at the same frequency as the above-mentioned specific frequency in free space, and α be the wavelength shortening by the dielectric around the antenna As a percentage

λ1 = α × λ0

Therefore, the size of the loop antenna can be reduced according to the wavelength shortening rate α.

  Further, in the present invention, the parasitic element 14 is positioned on one side of the dividing line with respect to the dividing line (the center line CL in the embodiment of FIG. 6A) that bisects the loop antenna 12 approximately equally. It is arranged so as not to reach the opposite region beyond this dividing line. The parasitic element 14 is perpendicular to a component parallel to a straight line connecting the counter electrodes of the loop viewed from the feeding points 16 and 17 of the loop antenna 12 (the center line CL in the embodiment of FIG. 6A). When divided into components, they are arranged in the vicinity of the loop antenna 12 so that there are always parallel components. That is, the parasitic element 14 according to the present invention is not composed of only a component perpendicular to the center line CL.

  This is because the parasitic element 14 is provided to receive a circularly polarized wave component that cannot be received by the loop antenna 12 as described above.

  FIG. 6B shows the configuration of a left-turning circularly polarized loop antenna 12 in the circularly polarized loop antenna 12 used in the present invention. Left-handed circularly polarized waves are used for radio waves for satellite digital broadcasting. This figure is a view of the loop antenna 12 as seen from the direction of arrival of the circularly polarized wave turning counterclockwise. The only difference between the left-turning circularly polarized loop antenna 12 and the right-turning circularly polarized loop antenna 12 is the position of the parasitic element 14. Therefore, the same components as those of the right-turning circularly polarized loop antenna 12 are denoted by the same reference numerals, and description thereof is omitted. In the left-turn circularly polarized loop antenna 12 shown in FIG. 6B, the parasitic terminal 14 is positioned at the parasitic power in the right-turn circularly polarized loop antenna 12 shown in FIG. The terminal 14 is symmetrical with respect to the straight line CL described above. Further, in the left-turning circularly polarized loop antenna 12, the feed terminal 16 is grounded.

  In this way, the position of the parasitic terminal 14 of the left-turning circularly polarized loop antenna 12 is set to be symmetrical with the position of the parasitic terminal 14 of the right-turning circularly polarized loop antenna 12. The reason is that the second portion 14B receives the vertical component of the left-handed circularly polarized wave and transmits the circularly polarized component received by the first portion 14A to the loop antenna 12.

  FIG. 7 (a) shows another configuration of the circular antenna 12 for circular polarization of right turn in the circular antenna 12 for circular polarization used in the present invention. The right-handed circularly polarized loop antenna 12 shown in this figure is viewed from the same direction as the right-turned circularly polarized loop antenna 12 described with reference to FIG. The only difference from the right-turning circularly polarized loop antenna 12 described in (a) is the position of the parasitic element 14. Therefore, the same components as those in FIG. 6A are denoted by the same reference numerals and the description thereof is omitted.

  In the clockwise circularly polarized loop antenna 12 described with reference to FIG. 6A, the parasitic element 14 is provided on the left side of the loop antenna 12. On the other hand, in the right-turn circularly polarized loop antenna 12 shown in FIG. 7A, the parasitic element 14 is on a straight line CL that connects the intermediate point between the feeding terminals 16 and 17 and the apex opposite thereto. A point symmetric with respect to the parasitic element 14 in FIG. 6A with respect to a certain center point CP, that is, a position obtained by rotating the parasitic element 14 in FIG. 6A 180 degrees around the center point CP. , Have been arranged. In the right-turning circularly polarized loop antenna 12, even if the parasitic element 14 is arranged at such a point-symmetrical position, the effect does not change. This is because the second portion 14B receives the vertical component of the right-hand circular polarization and transmits the vertical component of the circular polarization received by the first portion 14A to the antenna conductor of the loop antenna 12. This is because it can.

  FIG. 7B shows another configuration of the left-turn circularly polarized loop antenna 12 in the circularly polarized loop antenna 12 used in the present invention. The left-handed circularly polarized loop antenna 12 shown in this figure is viewed from the same direction as the left-turned circularly polarized loop antenna 12 described with reference to FIG. The only difference from the left-turned circularly polarized loop antenna 12 described in FIG. Therefore, the same components as those in FIG. 6B are denoted by the same reference numerals and the description thereof is omitted.

  In the right-turning circularly polarized loop antenna 12 described with reference to FIG. 6B, the parasitic element 14 is provided on the right side of the loop antenna 12. On the other hand, in the left-turn circularly polarized loop antenna 12 shown in FIG. 7 (b), the parasitic element 14 is on a straight line CL connecting the intermediate point of the feeding terminals 16 and 17 and the apex facing the feeding point. It is arranged at a point-symmetrical position with respect to the center point CP. In the left-turn circularly polarized loop antenna 12, even if the parasitic element 14 is arranged at such a point-symmetrical position, the effect does not change. This is because the vertical component of the left circularly polarized wave is received by the second portion 14B, and the vertical component of the circularly polarized wave received by the first portion 14A can be transmitted to the antenna conductor of the loop antenna 12. Because.

  FIGS. 8A to 9D show various arrangements of the parasitic elements 14 with respect to the loop antenna 12 when the shape of the antenna conductor of the loop antenna 12 is square. Here, it is assumed that the loop antenna 12 for circular polarization of right and left turns shown in FIGS. 6A and 6B is a basic shape, and the center point of the antenna conductor is CP.

  FIG. 8A shows the parasitic element 14 in the loop antenna 12 of FIG. 6A arranged at a position rotated 90 ° counterclockwise with respect to the center point CP. FIG. 8B shows the parasitic element 14 in the loop antenna 12 shown in FIG. 6B arranged at a position rotated clockwise by 90 degrees with respect to the center point CP. Even if the parasitic element 14 is arranged in this way, there is no difference in the circularly polarized wave reception performance of the loop antenna 12.

  FIG. 8C shows the same direction as the first portion 14A as it is without bending the second portion 14B of the parasitic element 14 in the loop antenna 12 of FIG. 6A with respect to the first portion 14A. It is an extension to The second portion 14B of the parasitic element 14 in the loop antenna 12 of FIG. 6B can be extended as it is in the same direction as the first portion 14A without being bent with respect to the first portion 14A. is there.

  On the other hand, FIG. 8D shows the parasitic element 14 shown in FIG. 8C arranged at a position rotated by 180 ° with respect to the center point CP of the loop antenna 12. A similar arrangement is possible for the left-turn circularly polarized loop antenna 12. Even if the parasitic element 14 is arranged in this way, there is no difference in the circularly polarized wave reception performance of the loop antenna 12.

  FIG. 9A shows an example in which the auxiliary conductor 9 is arranged in the horizontal direction below the loop antenna 12 with respect to the installation position of the loop antenna 12 shown in FIG. This embodiment will be described later. In FIG. 9B, another auxiliary parasitic element 141 similar to the parasitic element 14 of the loop antenna 12 shown in FIG. 6A is disposed at a point-symmetrical position with respect to the center point CP of the antenna conductor. It is a thing. FIG. 9C shows an auxiliary parasitic element 142 arranged substantially parallel to the outside of the parasitic element 14 shown in FIG. 6A. Further, FIG. 9D is a diagram in which auxiliary parasitic elements 142 and 143 are arranged on the outside of the parasitic element 14 and the auxiliary parasitic element 141 shown in FIG. is there. Increasing the number of parasitic elements improves the circular polarized wave reception performance of the loop antenna 12.

  FIG. 10 shows the configuration of the thin antenna 20 of the second embodiment of the present invention, which is viewed from the same direction as the thin antenna 10 of the first embodiment. The thin antenna 20 of the second embodiment is different from the thin antenna 10 of the first embodiment shown in FIG. 1 in that the arrangement of the TV antenna 13 and the tongue of the transparent film on which the loop antenna 12 is arranged. 11A is extended to the free end side, and the auxiliary conductor 9 described with reference to FIG. The auxiliary conductor 9 is provided outside the loop antenna 12 so as to be in contact with a virtual circle IC centered on the center point CP of the antenna conductor (see FIGS. 11A and 11B described later). Therefore, the same reference numerals are given to the same portions as those of the thin antenna 10 of the first embodiment, and the description thereof is omitted.

  Whether the auxiliary conductor 9 provided at the tip of the tongue portion 11A of the transparent film shown in FIG. 10 is made longer or shorter than half the wavelength of the radio wave received by the loop antenna 12. Thus, the directivity of the thin antenna 20 can be changed. The auxiliary conductor 9 may be one as shown in FIG. 10, or a plurality of auxiliary conductors 9 may be arranged. Further, a part of the TV antenna 13 installed in the thin antenna 20 may be used as an auxiliary conductor as shown in FIG.

  FIG. 11A shows an embodiment in which the length of the auxiliary conductor 9 is set to be 1/2 or more of the wavelength of the received radio wave of the loop antenna 12. As described above, when the length of the auxiliary conductor 9 is set to a length of ½ or more of the wavelength of the reception radio wave of the loop antenna 12, the reception directivity of the loop antenna 12, as shown in FIG. It becomes a directivity axis Z directed obliquely upward on the opposite side of the auxiliary conductor 9 with respect to the vertical axis Y standing at the center point CP of the antenna conductor. In FIG. 12A, the parasitic element 14 is not shown.

  FIG. 11B shows an embodiment in which the length of the auxiliary conductor 9 is set to a length less than ½ of the wavelength of the received radio wave of the loop antenna 12. Thus, when the length of the auxiliary conductor 9 is set to a length less than ½ of the wavelength of the reception radio wave of the loop antenna 12, the reception directivity of the loop antenna 12, as shown in FIG. It becomes a directivity axis X facing obliquely upward on the same side as the auxiliary conductor 9 with respect to the vertical axis Y standing at the center point CP of the antenna conductor. In FIG. 12B, the parasitic element 14 is not shown.

  Therefore, the thin antenna 20 having the loop antenna 12 in which the length of the auxiliary conductor 9 shown in FIG. 11A is ½ or more of the wavelength of the received radio wave of the loop antenna 12 is changed to that shown in FIG. As shown in FIG. 4, when the vehicle is attached to the inclined windshield 1 of the automobile 100, the direction of the directional axis of reception of the thin antenna 20 can be directed to the zenith direction indicated by the arrow Z. As a result, the reception performance of the thin antenna 20 in the zenith direction is improved. On the other hand, the thin antenna 20 having the loop antenna 12 in which the length of the auxiliary conductor 9 shown in FIG. 11B is less than ½ of the wavelength of the received radio wave of the loop antenna 12 is shown in FIG. As shown in FIG. 3, when the vehicle is attached to the inclined windshield 1 of the automobile 100, the direction of the directional axis of reception of the thin antenna 20 can be directed to a direction close to the horizontal direction indicated by the arrow X. As a result, the reception performance of the thin antenna 20 in the direction close to the horizontal is improved.

  FIG. 13A shows the configuration of the thin antenna 30 of the third embodiment of the present invention, and is a view of the thin antenna 30 as seen from the direction opposite to the direction of arrival of radio waves. The thin antenna 30 of the third embodiment is different from the thin antenna 10 of the first embodiment shown in FIG. 1 in that the arrangement of the TV antenna 13 and the tongue of the transparent film on which the loop antenna 12 is arranged. 11A is extended in the lateral direction, and only the loop antennas 121 and 122 are provided in the extended portion. Therefore, the same reference numerals are given to the same portions as those of the thin antenna 10 of the first embodiment, and the description thereof is omitted.

  In the loop antenna 121, the arrangement of the parasitic element 141 is the same as that in FIG. 6B (this figure is a view seen from the direction opposite to the arrival direction of the radio wave, so the arrangement of the parasitic element 141 is shown in FIG. Therefore, it is a loop antenna for receiving a left-handed circularly polarized wave. Reference numerals 161 and 171 denote power supply terminals. Further, in the loop antenna 122, the arrangement of the parasitic element 142 is the same as that in FIG. 6A (this figure is a view seen from the direction opposite to the arrival direction of the radio wave. 6 (a)), it is a loop antenna for receiving the right-handed circularly polarized wave similar to the loop antenna 12. However, the total length of the loop is shorter than that of the loop antenna 12. Therefore, the loop antenna 122 receives a higher-frequency right-handed circularly polarized wave. Reference numerals 162 and 172 denote power supply terminals.

  In the thin antenna 30 of the third embodiment, the transparent film tongue 11A is horizontally long, and in the thin antenna 10 of the first embodiment, the TV antenna 73 and its antenna connection terminal 79 are arranged. Feeding terminals 161, 162, 171, and 172 are provided at the positions. In this embodiment, the right portion of the transparent film 11 is extended to form an extension portion 11B, and the TV antenna 13 is folded back by the extension portion 11B to have a length corresponding to the wavelength of the TV reception frequency. Secured. Thus, a plurality of loop antennas can be mounted on the transparent film 11 in the thin antenna 30 of the present invention. As a result, the antenna mounting space for a plurality of types of radio waves can be reduced and the cables can be integrated, so that the mounting and mounting properties of the antenna on the vehicle can be improved, and the antenna installation cost can be reduced.

  FIG. 13B shows a configuration of a thin antenna 30S which is a modification of the thin antenna 30 of the third embodiment shown in FIG. 13A, and the thin antenna 30S is viewed from the direction opposite to the arrival direction of radio waves. FIG. The thin antenna 30S shown in (b) is different from the third embodiment shown in (a) in that the tongue piece 11A of the transparent film 11 on which the loop antenna 12 is arranged is connected to the antenna connection terminal 18 of the TV antenna 13. The antenna 150 for signal transmission / reception (for security) used in the vehicle anti-theft device and its antenna connection terminal 151 are provided at the extended portion, and the loop antennas 121 and 122 are provided. It is a point provided by the perforation 152 so that it can be independently cut from the tongue piece portion 11A. Accordingly, the same parts as those of the thin antenna 30 of the third embodiment are denoted by the same reference numerals and the description thereof is omitted.

  In the thin antenna 30S of this modified example, vehicle theft prevention can be connected, and the loop antennas 121 and 122 can be deleted by the perforation 152 when unnecessary.

  FIG. 19 shows the thin antenna 30S and the thin TV when the vehicle anti-theft 150 is connected to the security antenna 150 used in the vehicle anti-theft device provided in the thin antenna 30S shown in FIG. The connection of the antenna 50 with the navigation device 8 will be described. The security antenna 150 is connected to the vehicle antitheft device 153 via a connector 154 and a cable 155 connected to the connector 154. The vehicle antitheft device 153 may be built in the navigation device 8, and an amplifier that amplifies a signal transmitted and received by the antenna 150 may be provided in the middle of the cable 155 or in the connector 154. In this embodiment, the loop antennas 121 and 122 are not used.

  The loop antenna 12 provided in the thin antenna 30S is connected to the GPS receiver 81 built in the navigation device 8 using the connector 21 and the coaxial cable 2. Also in this embodiment, the amplifier 6 is built in the connector 21. The TV antenna 13 provided on the thin antenna 30S is connected to the selector 47 of the selector / amplifier 40 by the connector 31, the cable 2 (not shown), and the coaxial cable 4.

  The two TV antennas 51 and 52 provided in the thin TV antenna 50 are connected to a selector / amplifier 40 including a selector 47 and an amplifier 48 by a connector 31, a cable 2 and a coaxial cable 4 (not shown), respectively. It is connected to a TV tuner 82 built in the navigation device 8 through the coaxial cable 5. In addition to the GPS receiver 81 and the TV tuner 82, the navigation device 8 includes a map information storage medium 83, a liquid crystal display 84, and a controller 85, which are connected to each other via an internal bus 86. The configuration shown in FIG. 19 is the same as the configuration shown in FIG. 3 except that the thin antenna 10 is replaced with the thin antenna 30S. The functions of the respective members have been described with reference to FIG. .

  For the thin antenna 30S, instead of or in addition to the security antenna 150, a signal antenna used in a keyless entry system of an automobile or a signal used in a remote engine starting device The antenna can be mounted. In this case, the thin antenna 30S operates as an antenna for a keyless entry system or a remote engine starter. Further, the antenna for the vehicle antitheft device, the keyless entry system, and the remote engine starting device can be cut off when these devices are not connected.

  FIGS. 14A to 14D show arrangement examples of the parasitic elements 14 when the shape of the antenna conductor of the circularly polarized loop antenna 12 used in the thin antenna of the present invention is rectangular. These figures are views of the loop antenna 12 as seen from the direction of arrival of the right-handed circularly polarized wave.

  The loop antenna 12 in FIG. 14A includes a rectangular antenna conductor in which the antenna conductors on the parallel sides of the loop antenna 12 shown in FIG. 6A are extended by the same length in the lower left direction. The power supply terminals 16 and 17 are provided at one vertex. Also in this embodiment, the parasitic element 14 is electrically connected to the first portion 14A parallel to one side of the antenna conductor, and is bent with respect to the first portion 14A. The second portion 14B is connected to the second portion 14B. The second portion 14B is bent in a direction approaching the other side of the antenna conductor, but the distance between the second portion 14B and one side of the adjacent antenna conductor increases as the free end portion thereof. The power supply terminals 16 and 17 are grounded at the power supply terminal 17.

  The loop antenna 12 of FIG. 14B includes a rectangular antenna conductor having the same shape as the loop antenna 12 of FIG. 14A, and feed terminals 16 and 17 are provided at one vertex thereof. In the parasitic element 14 of this embodiment, the parasitic element 14 shown in FIG. 14A is provided at a point-symmetrical position with respect to the center point CP of the rectangular antenna conductor. The power supply terminals 16 and 17 are grounded at the power supply terminal 16.

  The loop antenna 12 in FIG. 14C includes a rectangular antenna conductor in which the antenna conductors on the parallel sides of the loop antenna 12 shown in FIG. 6A are extended by the same length in the lower right direction. The power supply terminals 16 and 17 are provided at one vertex. Also in this embodiment, the parasitic element 14 is electrically connected to the first portion 14A parallel to one side of the antenna conductor, and is bent with respect to the first portion 14A. The second portion 14B is connected to the second portion 14B. The second portion 14B is bent in a direction approaching the other side of the antenna conductor, but the distance between the second portion 14B and one side of the adjacent antenna conductor increases as the free end portion thereof. The power supply terminals 16 and 17 are grounded at the power supply terminal 17.

  The loop antenna 12 of FIG. 14D includes a rectangular antenna conductor having the same shape as the loop antenna 12 of FIG. 14C, and feed terminals 16 and 17 are provided at one vertex thereof. In the parasitic element 14 of this embodiment, the parasitic element 14 shown in FIG. 14C is provided at a point-symmetrical position with respect to the center point CP of the rectangular antenna conductor. The power supply terminals 16 and 17 are grounded at the power supply terminal 16.

  The shape of the antenna conductor of the circularly polarized wave receiving loop antenna 12 used in the thin antennas 10, 20, 30, 30S of the present invention can be various shapes other than the above-described square and rectangle. The shape will be described below.

  FIG. 15A shows an example of the arrangement of the parasitic elements 14 when the shape of the antenna conductor of the loop antenna 12 is a hexagon. In this example, both the first portion 14A and the second portion 14B of the parasitic element 14 are formed in parallel to two adjacent sides of the hexagonal antenna conductor. The second portion 14B may be further extended beyond the length of one side of the adjacent hexagonal antenna conductor. The parasitic element 14 can also be arranged at a position rotated by an integral multiple of 60 degrees with respect to the center point CP of the hexagonal antenna conductor. Further, as shown in FIG. 15B, the second portion 14B of the parasitic element 14 may be linearly extended without being bent with respect to the first portion 14A.

  FIG. 15C shows an example of the arrangement of the parasitic elements 12 when the shape of the antenna conductor of the loop antenna 12 is a triangle. In this example, the first portion 14A of the parasitic element 14 is formed in parallel with one side adjacent to the feeding terminal 16 of the triangular antenna conductor, and the second portion 14B is triangular with respect to the first portion 14A. The antenna conductor is bent toward the other side. The parasitic element 14 can also be disposed at a position rotated counterclockwise by 120 degrees with respect to the center point CP of the triangular antenna conductor.

  FIG. 15D shows still another example of the arrangement of the parasitic elements 14 when the shape of the antenna conductor of the loop antenna 12 is square. In the above-described embodiment, all the parasitic elements 14 are arranged outside the antenna conductor of the loop antenna 12, but in this embodiment, the parasitic elements 14 are arranged inside the antenna conductor of the loop antenna 12. The point is different. Thus, the parasitic element 14 can be disposed inside the antenna conductor regardless of the shape of the antenna conductor of the loop antenna 12.

  In the above embodiment, the shape of the antenna conductor of the loop antenna 12 is polygonal, but the shape of the antenna conductor may be circular, and the embodiment will be described.

  FIG. 16A shows an example of the arrangement of the parasitic elements 14 when the shape of the antenna conductor of the loop antenna 12 is circular. In this example, the first portion 14A of the parasitic element 14 is formed in a position parallel to one tangent of the circular antenna conductor and at a predetermined distance from the arc. The second portion 14B is bent and arranged on the side closer to the antenna conductor with respect to the first portion 14A. In this embodiment, the second portion 14B is arranged in parallel to a center line CL passing between the two power supply terminals 16 and 17 and the center point CP. As shown in FIG. 16B, the first portion 14A of the parasitic element 14 may be formed parallel (concentrically) to the arc-shaped antenna conductor of the loop antenna 12. Further, as shown in FIG. 16C, the first portion 14A and the second portion 14B of the parasitic element 14 are both connected to the center line CL between the two feeding terminals 16 and 17 and the center point CP. You may arrange | position in parallel with respect to. Furthermore, as shown in FIG. 16D, a part of the antenna conductor of the circular loop antenna 12 may be formed linearly to form a part 12P parallel to the first part 14A of the parasitic element 14. good.

  The shape of the antenna conductor of the loop antenna 12 that can be used for the thin antennas 10, 20, and 30 of the present invention, and the number and arrangement of the parasitic elements 14 are not limited to the above-described embodiments.

  FIG. 18 is a diagram for explaining specific dimensions in an embodiment of the circularly polarized thin loop antenna 12 and parasitic element 14 of the present invention described in FIG. First, various dimensions on the loop antenna 12 side will be described. In this embodiment, the feed terminals 16 and 17 have a length E in the short direction of 3 mm and a length F in the longitudinal direction of 5 mm, and the connecting conductor 27 connecting the feed terminals 16 and 17 and the antenna conductor. The length G is 10 mm. Moreover, the line-to-line dimension H of the connecting conductor 27 is 3 mm. Furthermore, the length K of one side of the square antenna conductor is 30 to 35 mm, and the pattern width J of the antenna conductor is 0.3 mm.

  Next, in the parasitic element 14, the length Z1 of the first portion 14A parallel to the antenna conductor is 15 to 25 mm, and the length Z of the second portion 14B electrically connected to the first portion 14A is 35. The total length Z including the first portion 14A and the second portion 14B is 55 to 75 mm. The distance M between the first portion 14A and the antenna conductor is 1.5 to 3.5 mm.

  The thin circular antenna 12 for circular polarization of the embodiment shown in FIG. 18 can receive GPS radio waves. The dimensions of this embodiment are merely examples. If the frequency of the received radio wave is different, the above-described dimensions can be increased or decreased in proportion to the frequency.

  Further, in the above-described embodiment, the thin antennas 10, 20, and 30 have been described in which the loop antenna 12 is formed on the transparent film 11 and attached to the back side of the windshield 1 of the automobile. Can be formed on a normal printed circuit board or on an opaque dielectric such as the surface of a resin case. Such a form is a household device having a communication function and uses a circularly polarized wave as a communication wave, for example, a wireless connection between a personal computer and its peripheral devices is a circularly polarized wave, a portable terminal, etc. It can be effectively applied to. Furthermore, in the above-described embodiments, the loop antenna 12 has been described for GPS. However, the antenna of the present invention can be applied as long as it is circularly polarized, and the use of the antenna is not limited to GPS.

It is a figure explaining the top view which shows the structure of the thin-shaped antenna of 1st Example of this invention, and the cable connected to this. (A) is a top view which shows the structure of the thin television antenna used with the thin antenna of this invention, (b) is the case where the thin antenna of FIG. 1 and the thin television antenna of (a) are installed in the windshield of a motor vehicle. FIG. 2 is a front perspective view of a vehicle interior showing connection with a navigation device. It is a circuit diagram which shows the connection of the thin antenna shown in FIG.2 (b), a thin television antenna, and a navigation apparatus. (A) is a figure explaining the connection of the loop antenna shown in FIG. 1 and the cable which attached the connector which incorporates amplifier at the front-end | tip, (b) is an example of the circuit structure inside the amplifier shown to (a). FIG. (A) is a diagram showing a state where a cable is connected to the loop antenna shown in FIG. 1 via a balance circuit and an amplifier, (b) is a circuit diagram showing an example of the balance circuit of (a), (c) is It is a circuit diagram which shows the other example of the balance circuit of (a). (A) is a top view which shows the structure of the thin antenna for right-turning circularly polarized wave reception among the circularly polarized antennas used for this invention, (b) is among the circularly polarized antennas used for this invention It is a top view which shows the structure of the thin antenna for circularly polarized wave reception of the left turn. (A) is a top view which shows another structure of the thin antenna for circularly polarized wave reception of the right turn among the circularly polarized antennas used for this invention, (b) is the circularly polarized antenna used for this invention It is a top view which shows another structure of the thin antenna for circularly polarized wave reception of the left turn of FIG. It is the figure which looked at the structural example of the loop antenna used for the thin antenna of this invention from the arrival direction of circularly polarized wave, (a) of the loop antenna which shows another example for receiving clockwise circularly polarized wave The figure which shows a structure, (b) is a figure which shows the structure of the loop antenna which shows another example for receiving left-turn circular polarization, (c) is another another for receiving right-turn circular polarization The figure which shows the structure of the loop antenna which shows an example, (d) is a figure which shows the structure of the loop antenna which shows another example for receiving clockwise circular polarization. It is the figure which looked at the structural example of the loop antenna for circular polarization used for the thin antenna of this invention from the arrival direction of circular polarization, (a) is the installation position of the loop antenna shown to Fig.6 (a). The figure which shows the example which has arrange | positioned the auxiliary | assistant conductor with respect to a horizontal direction with respect to the center point of a loop antenna with the auxiliary | assistant parasitic element similar to the parasitic element of the loop antenna shown in FIG. The figure which shows the example further provided in the point symmetrical position, (c) is the example which further arrange | positioned the auxiliary | assistant parasitic element on the outer side of the parasitic element of the loop antenna shown to Fig.6 (a) further in parallel with this. FIG. 6D is a diagram showing an example in which auxiliary parasitic elements are further arranged on the outside of the parasitic element and auxiliary parasitic element of the loop antenna shown in FIG. . It is a top view which shows the structure of the thin antenna of the 2nd Example of this invention. (A) is a figure which shows the Example which made the length of the auxiliary conductor 1/2 or more of the wavelength of the received electric wave of a loop antenna, (b) is the wavelength of the received electric wave of a loop antenna by the length of an auxiliary conductor. The figure which shows the Example made into the length less than 1/2 of this, (c) is a figure which shows the difference in the directivity of a thin antenna by the difference in the structure of (a) and (b). (A) is a figure explaining the directivity of reception of the loop antenna shown to Fig.11 (a), (b) is a figure explaining the directivity of reception of the loop antenna shown in FIG.11 (b). (A) is a top view which shows the structure of the thin antenna of the 3rd Example of this invention, (b) is a top view which shows the structure of the thin antenna of the modification of the 3rd Example of this invention. (A)-(d) is a figure which shows the example of various arrangement | positioning of a parasitic element when the shape of the antenna conductor of the loop antenna for circular polarization used for the thin antenna of this invention is made into a rectangle. (A) is a figure which shows an example of arrangement | positioning of a parasitic element when the shape of the antenna conductor of the loop antenna for circular polarization used for the thin antenna of this invention is a hexagon, (b) is the figure of this invention The figure which shows another example of arrangement | positioning of a parasitic element when the shape of the antenna conductor of the loop antenna for circular polarization used for a thin antenna is a hexagon, (c) is used for the thin antenna of this invention The figure which shows an example of arrangement | positioning of a parasitic element when the shape of the antenna conductor of a loop antenna for circular polarization is made into a triangle, (d) is a loop antenna for circular polarization used for the thin antenna of this invention. It is a figure which shows another example of arrangement | positioning of a parasitic element when an antenna conductor shape is made into a square. (A) is a figure which shows an example of arrangement | positioning of a parasitic element when the shape of the antenna conductor of the loop antenna for circular polarization used for the thin antenna of this invention is made into a circle, (b) In the thin antenna of this invention The figure which shows another example of arrangement | positioning of a parasitic element when the shape of the antenna conductor of the loop antenna for circular polarization used is circular, (c) is for circular polarization used for the thin antenna of this invention The figure which shows another example of arrangement | positioning of a parasitic element when the shape of the antenna conductor of a loop antenna is circular, (d) is the antenna conductor of the loop antenna for circular polarization used for the thin antenna of this invention. It is a figure which shows the example of arrangement | positioning of a parasitic element when a shape makes a part of circle and a straight line. 1A is a local cross-sectional view taken along line AA in FIG. 1, FIG. 1B is a local cross-sectional view showing a configuration of a modified embodiment of FIG. 1A, and FIG. It is a fragmentary sectional view which shows the state embedded in the dielectric material. It is a figure for demonstrating the specific dimension in one Example of the thin loop antenna for circularly polarized waves provided with the parasitic element of this invention. It is a circuit diagram which shows the connection of the thin antenna shown in FIG.13 (b), a thin television antenna, and a navigation apparatus.

Explanation of symbols

1 Windshield 2, 3, 4, 5 Cable 6 Amplifier 7 Balance circuit 8 Receiver (navigation device)
9 Auxiliary conductor 10 Thin antenna of the first embodiment 11 Transparent film 12, 121, 122 Loop antenna 13, 51, 52, 73 TV antenna 14, 141, 142 Parasitic element 14A First part 14B Second part 16 , 17, 161, 162, 171, 172 Feed terminal 18, 53, 54, 79 Antenna connection terminal 21, 31 Connector 40 Selector / amplifier 50 Thin TV antenna 150 Security antenna 153 Vehicle anti-theft device

Claims (17)

A loop antenna,
A parasitic element that is disposed in the vicinity of the loop antenna and is configured of an independent conductor with respect to the loop antenna , and
The parasitic element includes a conductor that receives a component that is parallel or nearly parallel to a straight line that connects the counter electrode of the loop viewed from the feeding point of the loop antenna,
The parasitic element is composed of a first part arranged close to the antenna conductor constituting the loop antenna, and a second part arranged electrically connected to the first part,
The second portion of the parasitic element is bent in a direction approaching parallel to a straight line connecting the counter electrode of the loop viewed from the feeding point of the loop antenna,
The loop antenna is a substantially square antenna conductor,
A feeding point is provided at one vertex of the square of the antenna conductor,
When the top of the antenna conductor having a rectangular feeding point is set to the top, the first portion of the parasitic element is parallel to or close to the lower right and / or upper left side of the antenna conductor. Place and
The loop antenna has two ends, one end receives radio waves, and the other end is grounded . A loop antenna,
A parasitic element that is disposed in the vicinity of the loop antenna and is configured of an independent conductor with respect to the loop antenna, and
The parasitic element includes a conductor that receives a component that is parallel or nearly parallel to a straight line that connects the counter electrode of the loop viewed from the feeding point of the loop antenna,
The parasitic element is composed of a first part arranged close to the antenna conductor constituting the loop antenna, and a second part arranged electrically connected to the first part,
The second portion of the parasitic element is bent in a direction approaching parallel to a straight line connecting the counter electrode of the loop viewed from the feeding point of the loop antenna,
The loop antenna is a substantially rectangular antenna conductor,
A feeding point is provided at one vertex of the square of the antenna conductor,
When the apex of the antenna conductor having a rectangular feeding point is on the top, the first portion of the parasitic element is arranged in a state parallel to or close to the upper right and / or lower left sides of the antenna conductor. And
The loop antenna has two ends, one end receives radio waves, and the other end is grounded . The antenna according to claim 1 or 2 , wherein the first portion of the parasitic element is arranged in a parallel or nearly parallel state with respect to a part of the antenna conductor. The second portion of the parasitic element is a straight line that is parallel or nearly parallel to a straight line that connects a counter electrode of the loop as viewed from a feeding point of the loop antenna . The antenna according to item 1 . The antenna according to any one of claims 1 to 3, wherein the second portion of the parasitic element is bent toward the feeding point as compared to the first portion of the parasitic element. The loop antenna is a rectangular antenna conductor,
The antenna according to any one of claims 1 to 5 , wherein a feeding point is provided at one vertex of a square of the antenna conductor. The loop antenna is a substantially square antenna conductor,
A feeding point is provided at one vertex of the square of the antenna conductor,
When the apex provided with the feeding point in the square of the antenna conductor is located in the upward direction, the first portion of the parasitic element is arranged in parallel to the lower right side of the antenna conductor, and the second portion from the upper end of the first part, according to any one of claims 1 to 5, characterized in that it is arranged to extend upward at a linear substantially parallel line passing through the vertices of the square Antenna. The loop antenna is a substantially square antenna conductor,
A feeding point is provided at one vertex of the square of the antenna conductor,
When it is assumed that the apex provided with the feeding point in the square of the antenna conductor is located in the upward direction, the first part of the parasitic element is arranged in parallel to the upper left side of the antenna conductor, and the second part from the lower end of the first part, according to any one of claims 1 to 5, characterized in that it is arranged to extend downward in a line substantially parallel line passing through the vertex of the square antenna. The loop antenna is a substantially square antenna conductor,
A feeding point is provided at one vertex of the square of the antenna conductor,
When the apex provided with the feeding point in the square of the antenna conductor is located in the upward direction, the first part of the parasitic element is arranged in parallel to the upper right side of the antenna conductor, and the second part from the lower end of the first part, according to any one of claims 1 to 5, characterized in that it is arranged to extend downward in a line substantially parallel line passing through the vertex of the square antenna. The loop antenna is a substantially square antenna conductor,
A feeding point is provided at one vertex of the square of the antenna conductor,
When it is assumed that the apex provided with the feeding point in the square of the antenna conductor is located in the upper direction, the first part of the parasitic element is arranged in parallel to the lower left side of the antenna conductor, and the second part from the upper end of the first part, according to any one of claims 1 to 5, characterized in that it is arranged to extend upward at a linear substantially parallel line passing through the vertex of the square antenna. Wherein the length of the parasitic element, any one of claims 1 to 10, characterized in that the transmission and / or the length of 1/2 of the length of an integral multiple of the received radio waves of a wavelength in the loop antenna 1 The antenna according to item. An in-vehicle GPS antenna provided on a glass of an automobile,
The antenna according to any one of claims 1 to 5 , wherein a total length of the parasitic element is 55 mm to 75 mm, and a first portion of the parasitic element is 15 mm to 25 mm. An in-vehicle antenna provided on a glass of an automobile,
The distance between the first portion of the parasitic element and a part of the conductor of the loop antenna that is parallel or nearly parallel to the first portion of the parasitic element is 1.5 mm to 75 mm. The antenna according to any one of claims 1 to 5 . The antenna according to any one of claims 1 to 13 , further comprising a substantially linear auxiliary conductor disposed so as to contact a virtual circle having the same center as that of the loop antenna. The antenna according to claim 14 , wherein the auxiliary conductor is a part of another antenna formed on the same surface as the loop antenna. The antenna according to any one of claims 1 to 13 , wherein another antenna is provided on the same surface as the arrangement surface of the loop antenna. The other antenna may be at least one of a TV radio wave, a radio radio wave, a car keyless entry system signal, a vehicle anti-theft device signal, and a remote engine starter signal. Item 15. The antenna according to Item 15 or 16 .

Images