JP2016010042A - Antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna device that is not required to be matched and can implement stable characteristics in spite of a compact design.SOLUTION: An antenna device has a first radiation element 22. A first ground element 24 is spaced from one end side of the first radiation element 22 and disposed substantially perpendicularly to the first radiation element 22. A passive element 26 is spaced from the other end side of the first radiation element 22, and disposed substantially perpendicularly to the first radiation element 22. The first ground element 24 and the passive element 26 are disposed substantially in parallel to each other. The passive element 26 is electrically connected to the first radiation element 22.

Description

  The present invention relates to antenna technology, and more particularly to an antenna device that supports circularly polarized radio waves.

  Circularly polarized waves are used in radio waves such as GPS (Global Positioning System). When such GPS radio waves are received by a vehicle such as an automobile, the antenna mounted on the vehicle is required to be downsized. Therefore, for example, a circularly polarized antenna composed of a parasitic element and a monopole has been proposed (see, for example, Patent Document 1).

JP 2005-236656 A

  In the background art, since there is no matching element, a matching circuit is required. Moreover, in order to operate as a monopole antenna, a large area ground is required. If the ground area is small, the antenna current is distributed in the coaxial cable, and therefore the antenna characteristics vary when the length of the coaxial cable changes.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique that does not require matching and realizes stable characteristics even if it is small.

  In order to solve the above-described problems, an antenna device according to an aspect of the present invention includes a radiating element, a ground element that is spaced apart from one end side of the radiating element and is substantially orthogonal to the radiating element, and the other end of the radiating element. A parasitic element that is spaced apart from the side and disposed substantially orthogonal to the radiating element. The parasitic element is electrically connected to the radiating element.

  According to the present invention, no matching is required, and stable characteristics can be realized even with a small size.

It is a figure which shows the external appearance of the vehicle by which the antenna which concerns on Example 1 of this invention is mounted. It is a front view of the antenna of FIG. It is a front view of another antenna of FIG. It is a perspective view of the circuit board of FIG. It is a front view of the circuit board of FIG. It is a front view of the antenna which concerns on Example 2 of this invention. It is a perspective view of the circuit board concerning Example 2 of the present invention. It is a front view of the circuit board of FIG. It is a figure which shows the structure of the communication system in which the antenna of FIG. 6 is used. FIGS. 10A to 10D are diagrams showing frame formats defined in the communication system of FIG. It is a figure which shows the structure of the vehicle-mounted terminal device mounted in the vehicle of FIG. It is a front view of the antenna which concerns on Example 3 of this invention. It is a front view of the circuit board concerning Example 4 of the present invention. It is a front view of the circuit board concerning Example 5 of the present invention.

Example 1
Before specifically describing Example 1 of the present invention, an outline of this example will be described. Example 1 relates to an antenna provided on a transparent film. In particular, the antenna is a GPS antenna mounted on a vehicle. In recent years, in order to facilitate installation work, a configuration in which a GPS antenna is attached to a windshield of a vehicle has become common. The GPS antenna is a circularly polarized antenna. In the circularly polarized antenna, the length of the element for operating as a circularly polarized wave does not necessarily match the length for matching at 50Ω, and a matching circuit is required. become. As described above, the GPS film antenna attached to the windshield requires improved efficiency, downsizing, improved ease of matching, and stable characteristics.

  In order to cope with this, the antenna according to the first embodiment has a configuration in which a parasitic element is added to an L-shaped dipole. One side of the L-shaped dipole is a radiating element, the other side is a ground element, and the radiating element and the ground element are separated from each other. The parasitic element is disposed close to one end of the radiating element, is substantially orthogonal to the radiating element, and is substantially parallel to the ground element. Here, the ground element operates as a matching element. By arranging the parasitic element so as to face the ground element across the radiating element, the three elements of the ground element, the radiating element, and the parasitic element may be arranged in a U shape.

  FIG. 1 shows an appearance of a vehicle 12 on which an antenna 20 according to Embodiment 1 of the present invention is mounted. An antenna 20 and a circuit board 110 are installed on the windshield of the vehicle 12. More specifically, the antenna 20 and the circuit board 110 are arranged in this order from the windshield toward the vehicle interior. The antenna 20 is connected to the circuit board 110, and details will be described later. One end of a coaxial cable 80 is connected to the circuit board 110. The other end of the coaxial cable 80 is connected to an in-vehicle terminal device (not shown). With such a configuration, the antenna 20 receives a signal from a GPS satellite and outputs the received signal to the circuit board 110. The circuit board 110 performs a predetermined process on the received signal and outputs the result to the in-vehicle terminal device via the coaxial cable 80. The combination of the antenna 20 and the circuit board 110 may be combined as an antenna device.

  FIG. 2 is a front view of the antenna 20. The antenna 20 includes a transparent film 38, a first radiating element 22, a first ground element 24, and a parasitic element 26 provided on the transparent film 38. The first radiating element 22 includes a first power supply pad 28, and the first ground element 24 includes a ground pad 30. The X-axis, Y-axis, and Z-axis are defined in the direction shown in the drawing, and in particular, the Z-axis is defined in the direction from the front to the back of the drawing, that is, the direction from the inside of the vehicle to the outside of the vehicle in the windshield portion of FIG. Yes. The length of the transparent film 38 in the X-axis direction is, for example, 60 mm, and the length in the Y-axis direction is, for example, 40 mm.

  The first radiating element 22 has a long rectangular shape in the Y-axis direction, and resonates at 1.575 GHz which is a GPS frequency. A length L1 of the first radiating element 22 in the Y-axis direction is, for example, 24 mm. A first power supply pad 28 is provided at the left end of the first radiating element 22. The first power supply pad 28 is connected to a circuit board 110 (not shown).

  The first ground element 24 has a rectangular shape that is long in the X-axis direction. The length L2 of the first ground element 24 in the X-axis direction is, for example, 32 mm. The upper end portion of the first ground element 24 is disposed on the left side of the left end portion of the first radiating element 22 so as to be separated from the left end portion side of the first radiating element 22. The first ground element 24 is disposed substantially orthogonal to the first radiating element 22. “Abbreviated” means that it may be shifted within an error range. The first ground element 24 and the first radiating element 22 constitute an L-shaped dipole antenna. The first ground element 24 is used as a matching element, and its length is determined so that impedance is matched. A ground pad 30 is provided at the upper end of the first ground element 24. The ground pad 30 is connected to a circuit board 110 (not shown).

  The parasitic element 26 has a rectangular shape that is long in the X-axis direction. The length L3 of the parasitic element 26 in the X-axis direction is, for example, 46 mm. The upper end portion of the parasitic element 26 is on the right end portion side of the first radiating element 22 on the right end portion of the first radiating element 22, that is, below the end portion where the first feeding pad 28 is not disposed. It is arrange | positioned away from. The parasitic element 26 is disposed substantially orthogonal to the first radiating element 22 and is disposed substantially parallel to the first radiating element 24, so that the first ground element 24 and the first radiating element 22 are disposed. The three elements of the parasitic element 26 are arranged in a “U” shape. Here, a gap G <b> 1 is provided between the right end of the first radiating element 22 and the upper end of the parasitic element 26, so that the parasitic element 26 is electrically connected to the first radiating element 22. Connected to. The gap G1 is the distance between the first radiating element 22 and the parasitic element 26, and is related to the degree of capacitive coupling between the two elements. The smaller the gap G1, the greater the capacitive coupling between the two elements.

  When three types of parameters, the length L1 of the first radiating element 22, the length L3 of the parasitic element 26, and the gap G1, are adjusted, the antenna current flowing through the first radiating element 22 and the parasitic element 26 that are substantially orthogonal to each other is adjusted. The direction varies depending on the phase (time). The antenna 20 operates as a right-handed circularly polarized antenna by adjusting the three types of parameters so that the current rotates clockwise with time as seen from the direction radiating from the antenna 20.

  The first radiating element 22, the first ground element 24, and the parasitic element 26 are disposed on a transparent film 38 made of polyethylene terephthalate resin (PET resin) or the like, and have a total light transmittance (light transmittance) in the visible region. It is formed of 80% or more transparent conductive material. Here, the total light transmittance is the ratio of the total transmitted light beam to the parallel incident light beam. The transparent conductive material constituting the first radiating element 22, the first ground element 24, and the parasitic element 26 is formed by etching a 12 μm thick blackened copper foil formed on the transparent film 38 into a mesh shape (lattice shape). It is formed by doing. In the etching process, for example, the mesh line width is 15 μm and the mesh interval is 900 μm.

  FIG. 3 is a front view of another antenna 20 different from FIG. The antenna 20 includes the same components as in FIG. The 1st radiation element 22 and the parasitic element 26 are arrange | positioned on the transparent film 38 similarly to FIG. The lower end portion of the first ground element 24 is disposed on the left side of the left end portion of the first radiating element 22 so as to be separated from the left end portion side of the first radiating element 22. The first ground element 24 is disposed substantially orthogonal to the first radiating element 22. A ground pad 30 is provided at the lower end of the first ground element 24. With such an arrangement, the first ground element 24 and the parasitic element 26 are arranged substantially in parallel, but are not arranged to face each other.

  FIG. 4 is a perspective view of the circuit board 110. The circuit board 110 includes a ground 112, a first power supply terminal 114, and a ground terminal 116. The coaxial cable 80 is connected to the circuit board 110. A ground 112 is disposed on a part of one surface side of the circuit board 110. The circuit board 110 is provided with a first power supply terminal 114, and the ground 112 is provided with a ground terminal 116. The first power supply terminal 114 is connected to the first power supply pad 28 of FIG. 2 or FIG. 3, and the ground terminal 116 is connected to the ground pad 30 of FIG. 2 or FIG. The length of the circuit board 110 in the x-axis direction is, for example, 11 mm, and the length in the y-axis direction is, for example, 32 mm.

  FIG. 5 is a front view of the circuit board 110. The circuit board 110 includes a ground 112, a first power supply terminal 114, a GPS band matching circuit 130, a GPS band pass filter 132, and a first LNA 134. The GPS band matching circuit 130 is connected to the first power supply terminal 114 and inputs a signal from the first power supply pad 28 (not shown) via the first power supply terminal 114. The GPS band pass filter 132 is connected to the GPS band matching circuit 130 and receives a signal from the GPS band matching circuit 130. The GPS band pass filter 132 allows a GPS band signal to pass and blocks other bands. The first LNA 134 is an LNA (Low Noise Amplifier). The first LNA 134 is connected to the GPS band pass filter 132 and amplifies the signal from the GPS band pass filter 132. The first LNA 134 connects the coaxial cable 80 and outputs a signal to an in-vehicle terminal device (not shown) via the coaxial cable 80.

  According to the present embodiment, the GPS antenna can be configured with a simple structure including three elements (first radiating element 22, first ground element 24, and parasitic element 26). Further, it is possible to obtain a circular polarization performance with a small size and a high gain. In addition, when power is supplied through a coaxial cable, the antenna current is distributed in the first ground element 24, and the antenna current distributed in the coaxial cable can be suppressed. In addition, since the antenna current distributed in the coaxial cable is suppressed, variations in antenna characteristics due to changes in the routing of the coaxial cable can be suppressed. In addition, a large ground such as a monopole antenna can be eliminated.

  Further, by using the first ground element 24 as a matching element and changing the length L2, impedance can be matched and a matching circuit can be made unnecessary. Further, since the three elements (the first radiating element 22, the first ground element 24, and the parasitic element 26) constituting the circularly polarized antenna are arranged in a U shape, the size can be reduced. Moreover, since it is miniaturized, space can be saved.

  Further, since the first ground element 24 and the parasitic element 26 are made of a transparent conductive material having a light transmittance of 80% or more, the width of each element can be increased. Further, since the element width is increased, the antenna performance can be improved. Further, since the first ground element 24 and the parasitic element 26 are made of a transparent conductive material having a light transmittance of 80% or more, visibility can be improved. In addition, since three types of parameters of the length L1 of the first radiating element 22, the length L3 of the parasitic element 26, and the gap G1 are adjusted, the direction of the antenna current can be changed depending on the phase (time). Further, by adjusting the above parameters, the antenna 20 can be operated as a right-hand circularly polarized antenna.

(Example 2)
Example 2 is related with the antenna provided on the transparent film similarly to Example 1, and installed in the vehicle. The antenna according to the first embodiment corresponds to GPS. On the other hand, the antenna according to the second embodiment is compatible with ITS (Intelligent Transport Systems) and DTV (Digital TeleVision) in addition to GPS. As described above, the GPS band is 1.575 GHz, but since the ITS / DTV band is 470 MHz to 765 MHz, these are different frequency bands. When an antenna corresponding to these frequency bands is installed on the windshield, further miniaturization of the antenna is required while suppressing deterioration of the antenna performance.

  To cope with this, the antenna according to the second embodiment includes a linearly polarized antenna in the ITS / DTV band in addition to the circularly polarized antenna in the GPS band described above. The linearly polarized antenna has an L-shaped dipole configuration and is arranged around the outside of the circularly polarized antenna. At this time, the ground element of the linearly polarized antenna is arranged so as to be farther from the radiating element of the circularly polarized antenna than the radiating element of the linearly polarized antenna. The ground element of the linearly polarized antenna is formed integrally with the ground element of the circularly polarized antenna. From the above-described frequency relationship, it can be said that the operating frequency of the linearly polarized antenna is lower than that of the circularly polarized antenna. Here, it demonstrates centering on the difference from before.

  FIG. 6 is a front view of the antenna 20 according to the second embodiment of the present invention. The antenna 20 includes a transparent film 38, a first radiating element 22, a first ground element 24, a parasitic element 26, a second radiating element 32, and a second ground element 34 provided on the transparent film 38. The first radiating element 22 includes a first power supply pad 28, the first ground element 24 includes a ground pad 30, and the second radiating element 32 includes a second power supply pad 36. The length of the transparent film 38 in Example 2 in the X-axis direction is, for example, 65 mm, and the length in the Y-axis direction is, for example, 133 mm.

  The first radiating element 22, the first ground element 24, and the parasitic element 26 are arranged in the same manner as in FIG. The second radiating element 32 has a rectangular shape that is long in the Y-axis direction, and resonates at 470 MHz to 765 MHz, which is the frequency of ITS / DTV. The length L4 of the second radiating element 32 in the Y-axis direction is, for example, 119 mm and is longer than the first radiating element 22. The second radiating elements 32 are juxtaposed in parallel while facing the first radiating elements 22. A second power supply pad 36 is provided alongside the first power supply pad 28 at the left end of the second radiating element 32. The second radiating element 32 is also connected to the circuit board 110 (not shown). The second radiating element 32 can be said to be an additional radiating element.

  The second ground element 34 has a right end disposed at a position spaced from the left end of the second radiating element 32 and extends leftward from the right end in the Y-axis direction. The second ground element 34 is bent and extended downward in the X-axis direction. Thus, the second ground element 34 has an L shape (length L5), and at least a part of the second ground element 34 is disposed substantially orthogonal to the second radiating element 32. The second ground element 34 and the second radiating element 32 constitute an L-shaped dipole antenna. The second ground element 34 can be said to be an additional ground element. The second radiating element 32 and the second ground element 34 are disposed on the outer periphery so as to surround the upper side and the left side of the first radiating element 22, the first ground element 24, and the parasitic element 26. At this time, the second ground element 34 is disposed so as to be farther from the first radiating element 22 than the second radiating element 32.

  The second ground element 34 extends downward from the right end in the X-axis direction and is connected to the ground pad 30. Here, the first ground element 24 and the second ground element 34 may be integrally formed. Further, the second radiating element 32 and the second ground element 34 also have a total light transmittance (light transmittance) of 80% in the visible region, like the first radiating element 22, the first ground element 24, and the parasitic element 26. It is formed of the above transparent conductive material (blackened copper foil processed into a mesh shape).

  FIG. 7 is a perspective view of the circuit board 110 according to the second embodiment of the present invention. The circuit board 110 includes a ground 112, a first power supply terminal 114, a ground terminal 116, and a second power supply terminal 118. Instead of the coaxial cable 80 in FIG. 4, the first coaxial cable 82 and the second coaxial cable 84 are connected to the circuit board 110. A ground 112 is disposed on a part of one surface side of the circuit board 110. The circuit board 110 is provided with a first power supply terminal 114 and a second power supply terminal 118, and the ground 112 is provided with a ground terminal 116. The first power supply terminal 114 is connected to the first power supply pad 28 in FIG. 6, the second power supply terminal 118 is connected to the second power supply pad 36 in FIG. 6, and the ground terminal 116 is connected to the ground pad 30 in FIG. Connected.

  FIG. 8 is a front view of the circuit board 110. The circuit board 110 includes a ground 112, a first feeding terminal 114, a GPS band matching circuit 130, a GPS band pass filter 132, a first LNA 134, a second feeding terminal 118, an ITS / DTV band matching circuit 136, and a low-pass filter 138. . The first power supply terminal 114, the GPS band matching circuit 130, the GPS band pass filter 132, and the first LNA 134 are the same as those in FIG. 5, and the first coaxial cable 82 corresponds to the coaxial cable 80 in FIG. The ITS / DTV band matching circuit 136 is connected to the second power supply terminal 118 and inputs / outputs a signal to / from the second power supply pad 36 (not shown) via the second power supply terminal 118. The low-pass filter 138 is connected to the ITS / DTV band matching circuit 136, passes the low-frequency component, and blocks the GPS band signal. The low-pass filter 138 connects the second coaxial cable 84, and the second coaxial cable 84 is connected to an in-vehicle terminal device (not shown). The second coaxial cable 84 transmits an ITS band signal and a DTV band signal. The length of the circuit board 110 in the x-axis direction is, for example, 11 mm, and the length in the y-axis direction is, for example, 32 mm.

  FIG. 9 shows a configuration of the communication system 100 in which the antenna 20 is used. The communication system 100 corresponds to ITS. This corresponds to a case where one intersection is viewed from above. The communication system 100 includes a base station device 10, a first vehicle 12a, a second vehicle 12b, a third vehicle 12c, a fourth vehicle 12d, a fifth vehicle 12e, a sixth vehicle 12f, and a seventh vehicle 12g, collectively referred to as a vehicle 12. , An eighth vehicle 12h, a ninth vehicle 12i, a tenth vehicle 12j, and a network 202. Here, only the first vehicle 12a is shown, but the vehicle-mounted terminal device 14 is mounted on each vehicle 12. An antenna 40 is included in the in-vehicle terminal device 14. An area 212 is formed around the base station apparatus 10, and an outside area 214 is formed outside the area 212. The antenna 40 corresponds to, for example, a part of the antenna 20 in the second embodiment (the second radiating element 32 and the second ground element 34 in FIG. 6).

  As shown in the drawing, the road that goes in the horizontal direction of the drawing, that is, the left and right direction, intersects the vertical direction of the drawing, that is, the road that goes in the up and down direction, at the center. Here, the upper side of the drawing corresponds to the direction “north”, the left side corresponds to the direction “west”, the lower side corresponds to the direction “south”, and the right side corresponds to the direction “east”. The intersection of the two roads is an “intersection”. The first vehicle 12a and the second vehicle 12b are traveling from left to right, and the third vehicle 12c, the fourth vehicle 12d, the ninth vehicle 12i, and the tenth vehicle 12j are traveling from right to left. Yes. Further, the fifth vehicle 12e and the sixth vehicle 12f are traveling from the top to the bottom, and the seventh vehicle 12g and the eighth vehicle 12h are traveling from the bottom to the top. Only the ninth vehicle 12 i and the tenth vehicle 12 j exist outside the area 214, and other vehicles exist within the area 212.

  In the communication system 100, the base station apparatus 10 is fixedly installed at an intersection. The base station device 10 controls communication between terminal devices. Base station apparatus 10 repeatedly generates a frame including a plurality of subframes based on a signal received from a GPS satellite (not shown) or a frame formed by another base station apparatus 10 (not shown). Here, the road vehicle transmission period can be set at the head of each subframe.

  The base station apparatus 10 selects a subframe in which the road and vehicle transmission period is not set by another base station apparatus 10 from among a plurality of subframes in the frame. The base station apparatus 10 sets a road and vehicle transmission period at the beginning of the selected subframe. The base station apparatus 10 notifies the packet signal in the set road and vehicle transmission period. In the road and vehicle transmission period, a plurality of packet signals may be notified. The packet signal includes, for example, accident information, traffic jam information, signal information, and the like. Note that the packet signal also includes information related to the timing when the road and vehicle transmission period is set and control information related to the frame.

  FIGS. 10A to 10D show frame formats defined in the communication system 100. FIG. FIG. 10A shows the structure of the frame. The frame is formed of N subframes indicated as the first subframe to the Nth subframe. It can be said that the frame is formed by multiplexing the subframes that can be used for notification by the in-vehicle terminal device 14 for a plurality of times. For example, when the frame length is 100 msec and N is 16, a subframe having a length of 6.25 msec is defined. N may be other than 16.

  FIG. 10B shows a configuration of a frame generated by the first base station apparatus 10a (not shown). The first base station apparatus 10a sets a road and vehicle transmission period at the beginning of the first subframe. Moreover, the 1st base station apparatus 10a sets a vehicle transmission period following a road and vehicle transmission period in a 1st sub-frame. The vehicle transmission period is a period during which the in-vehicle terminal device 14 can notify the packet signal. That is, the first base station apparatus 10a can notify the packet signal in the road and vehicle transmission period which is the head period of the first subframe, and is used for in-vehicle use in the vehicle and vehicle transmission period other than the road and vehicle transmission period in the frame. It is defined that the terminal device 14 can notify the packet signal. Furthermore, the first base station apparatus 10a sets only the vehicle transmission period from the second subframe to the Nth subframe.

  FIG. 10C shows a configuration of a frame generated by the second base station apparatus 10b (not shown). The second base station apparatus 10b sets a road and vehicle transmission period at the beginning of the second subframe. Also, the second base station apparatus 10b sets the vehicle transmission period from the first stage of the road and vehicle transmission period in the second subframe, from the first subframe and the third subframe to the Nth subframe. FIG. 10D shows a configuration of a frame generated by a third base station apparatus 10c (not shown). The third base station apparatus 10c sets a road and vehicle transmission period at the beginning of the third subframe. In addition, the third base station apparatus 10c sets the vehicle transmission period from the first stage of the road and vehicle transmission period in the third subframe, the first subframe, the second subframe, and the fourth subframe to the Nth subframe. As described above, the plurality of base station apparatuses 10 select different subframes, and set the road and vehicle transmission period at the head portion of the selected subframe. Returning to FIG.

  As described above, the in-vehicle terminal device 14 is mounted on the vehicle 12 and is movable. When receiving the packet signal from the base station device 10, the in-vehicle terminal device 14 estimates that the vehicle-mounted terminal device 14 exists in the area 212. When the in-vehicle terminal device 14 exists in the area 212, the in-vehicle terminal device 14 generates a frame based on the control information included in the packet signal, in particular, the information on the timing when the road and vehicle transmission period is set and the information on the frame. As a result, the frame generated in each of the plurality of in-vehicle terminal devices 14 is synchronized with the frame generated in the base station device 10. The in-vehicle terminal device 14 notifies the packet signal during the vehicle transmission period. Here, CSMA / CA (Carrier Sense Multiple Access with Collision Avidance) is executed in the vehicle transmission period. On the other hand, when it is estimated that the in-vehicle terminal device 14 is outside the area 214, the in-vehicle terminal device 14 notifies the packet signal by executing CSMA / CA regardless of the frame configuration.

  FIG. 11 shows the configuration of the in-vehicle terminal device 14 mounted on the vehicle 12. The in-vehicle terminal device 14 includes an antenna 40, an RF unit 42, a modem unit 44, a processing unit 46, and a control unit 48. The processing unit 46 includes a timing specifying unit 50, a transfer determination unit 56, an acquisition unit 58, and a notification unit 60. The generation unit 62 is included. The timing specifying unit 50 includes an extraction unit 52 and a carrier sense unit 54. In addition, since the structure regarding DTV is well-known, description is abbreviate | omitted here.

  The RF unit 42 operates corresponding to RF (Radio Frequency). The RF unit 42 receives a packet signal from the base station device 10 and another in-vehicle terminal device 14 (not shown) by the antenna 40 as a reception process. The RF unit 42 performs frequency conversion on the received radio frequency packet signal to generate a baseband packet signal. Further, the RF unit 42 outputs the baseband packet signal to the modem unit 44. In general, baseband packet signals are formed by in-phase and quadrature components, so two signal lines should be shown, but here only one signal line is shown for clarity. Shall be shown. The RF unit 42 also includes an LNA (Low Noise Amplifier), a mixer, an AGC (Automatic Gain Control), and an A / D conversion unit.

  As a transmission process, the RF unit 42 performs frequency conversion on the baseband packet signal input from the modem unit 44 to generate a radio frequency packet signal. Further, the RF unit 42 transmits a radio frequency packet signal from the antenna 40. The RF unit 42 also includes a PA (Power Amplifier), a mixer, and a D / A conversion unit.

  The modem unit 44 demodulates the baseband packet signal from the RF unit 42 as a reception process. Further, the modem unit 44 outputs the demodulated result to the processing unit 46. Further, the modem unit 44 modulates the data from the processing unit 46 as a transmission process. Further, the modem unit 44 outputs the modulated result to the RF unit 42 as a baseband packet signal. Here, since the communication system 100 corresponds to an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme, the modem unit 44 also performs FFT (Fast Fourier Transform) as reception processing and IFFT (Inverse Fast Trans) as transmission processing. Also execute.

  When the demodulation result from the modem unit 44 is a packet signal from the base station device 10 (not shown), the extraction unit 52 estimates that the signal is present in the area 212 in FIG. 3 and is mounted on the vehicle at the time of the base station device 10. The time of the terminal device 14 is synchronized. Furthermore, the timing of the sub-frame where the road and vehicle transmission period is arranged is specified. The extraction unit 52 generates a frame based on the timing of the subframe and the content of the message header of the packet signal, specifically, the content of the road and vehicle transmission period length. As a result, the extraction unit 52 generates a frame synchronized with the frame formed in the base station device 10. When receiving packets from a plurality of base station apparatuses 10, a frame is generated by combining subframes in which road and vehicle transmission periods of the packets are arranged. The extraction unit 52 selects a vehicle transmission period. When the vehicle transmission period is selected, the extraction unit 52 outputs information on the frame and subframe timing and the vehicle transmission period to the carrier sense unit 54.

  On the other hand, when the extraction unit 52 has not received the packet signal of the base station, the extraction unit 52 estimates that the extraction unit 52 exists outside the area 214 in FIG. When it is estimated that the extraction unit 52 exists outside the area 214, the extraction unit 52 selects a timing unrelated to the frame configuration. When the extraction unit 52 selects a timing unrelated to the frame configuration, the extraction unit 52 instructs the carrier sense unit 54 to execute carrier sense.

  The carrier sense unit 54 receives information regarding the timing of the frames and subframes and the vehicle transmission period from the extraction unit 52. The carrier sense unit 54 measures the interference power by executing carrier sense during the vehicle transmission period. Moreover, the carrier sense part 54 determines the transmission timing in a vehicle transmission period based on interference power. More specifically, the carrier sense unit 54 stores a predetermined threshold value in advance, and compares the interference power with the threshold value. If the interference power is smaller than the threshold value, the carrier sense unit 54 determines the transmission timing. When the carrier sense unit 54 is instructed by the extraction unit 52 to execute carrier sense, the carrier sense unit 54 determines the transmission timing by executing CSMA without considering the frame configuration. The carrier sense unit 54 notifies the generation unit 62 of the determined transmission timing.

  The acquisition unit 58 includes a GPS receiver, a gyro sensor, a vehicle speed sensor, and the like (not shown). Based on data supplied from the GPS receiver, the presence position, the traveling direction, the moving speed, and the like (hereinafter referred to as “position”). (Collectively referred to as “information”). The existence position is indicated by latitude and longitude. Since a known technique may be used for these acquisitions, description thereof is omitted here. The acquisition unit 58 outputs the position information to the generation unit 62.

  The transfer determination unit 56 controls the transfer of the message header. The message header includes, for example, information on a road and vehicle transmission period. The transfer determination unit 56 extracts a message header from the packet signal. When the packet signal is directly transmitted from the base station apparatus 10, for example, “transfer twice” is set, but when the packet signal is transmitted to another in-vehicle terminal apparatus 14, The transfer count is reduced by 1 and set to the value of “transfer once”. The transfer determination unit 56 selects a message header to be transferred from the extracted message header. Here, for example, the message header with the largest number of transfers is selected. In addition, the transfer determination unit 56 may generate a new message header by combining the contents included in the plurality of message headers. The transfer determination unit 56 outputs the message header to be selected to the generation unit 62. At that time, the transfer determination unit 56 decreases the transfer count by one.

  The generation unit 62 receives position information from the acquisition unit 58 and receives a message header from the transfer determination unit 56. The generation unit 62 generates a packet signal including position information and a message header. The processing unit 46 broadcasts the generated packet signal via the modulation / demodulation unit 44, the RF unit 42, and the antenna 40 at the transmission timing determined by the carrier sense unit 54.

  The notification unit 60 acquires the packet signal from the base station device 10 (not shown) and the packet signal from the other in-vehicle terminal device 14 (not shown) via the extraction unit 52. As a process for the acquired packet signal, the notification unit 60 notifies the driver of the approach of another vehicle 12 (not shown) or the like via a monitor or a speaker according to the content of the data stored in the packet signal. Further, the notification unit 60 notifies the driver of obstacle detection information, traffic jam information, lamp color information, and the like via a monitor or a speaker. In such a configuration, an antenna (not shown) in the acquisition unit 58 corresponds to the first radiating element 22, the first ground element 24, and the parasitic element 26 in FIG. It corresponds to the second radiating element 32 and the second ground element 34. The antenna 20 is configured as a three-wave integrated antenna including the antenna in the acquisition unit 58 and the antenna 40.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it can be realized by a program loaded in the memory, but here it is realized by their cooperation. Draw functional blocks. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms only by hardware, or by a combination of hardware and software.

  According to the present embodiment, since the second radiating element 32 and the second ground element 34 of the linearly polarized antenna having a frequency lower than that of the circularly polarized antenna and requiring an area are disposed outside, the linearly polarized antenna The area can be increased. Moreover, since the area is increased, the antenna characteristics can be improved. Moreover, since the 1st radiation element 22 is arrange | positioned away from the 2nd ground element 34, the performance deterioration of a circularly polarized wave antenna can be suppressed. Further, since the first ground element 24 and the second ground element 34 are shared, the number of ground pads can be reduced to one. Further, since the number of ground pads is one, the configuration can be facilitated.

(Example 3)
Example 3 relates to an antenna provided on a transparent film and installed in a vehicle, as before. In addition to the GPS, the antenna according to the third embodiment is compatible with ITS and DTV, but the shape is different from that of the second embodiment. Here, it demonstrates centering on the difference from before.

  FIG. 12 is a front view of the antenna 20 according to the third embodiment of the present invention. The antenna 20 includes a transparent film 38, a first radiating element 22 provided on the transparent film 38, a first ground element 24, a parasitic element 26, a first feeding pad 28, a ground pad 30, a second radiating element 70, A second ground element 72 and a second power supply pad 74 are included. The first radiating element 22 to the ground pad 30 are arranged in the same manner as in FIG. The second radiating element 70 corresponds to the second radiating element 32 of FIG. 6, but unlike the second radiating element 32, the area of the right open end is larger than the area of the left end. Is done. The second ground element 72 corresponds to the second ground element 34 of FIG. 6, but is formed so that the area at the open end on the lower left side and the bent part on the upper left side is larger than the other parts. Each element is formed of a transparent conductive material (blackened copper foil processed into a mesh shape) having a light transmittance of 80% or more, as in Example 2.

  According to this embodiment, the second radiating element 32 can be widened. In addition, since only the tip away from the first radiating element 22 is enlarged, the influence on the performance of the first radiating element 22 can be suppressed.

Example 4
The fourth embodiment relates to an antenna provided on a transparent film and installed in a vehicle, and more particularly to a circuit board connected to the antenna according to the second or third embodiment. In Example 2 or 3, another coaxial cable is used for GPS and ITS / DTV. On the other hand, in Example 4, one coaxial cable is used for GPS and ITS / DTV. Here, it demonstrates centering on the difference from before.

  FIG. 13 is a front view of the circuit board 110 according to the fourth embodiment of the present invention. The circuit board 110 includes a ground 112, a first power supply terminal 114, a GPS band matching circuit 130, a GPS band pass filter 132, a first LNA 134, an ITS / DTV band cut-off filter 140, a second power supply terminal 118, a low-pass filter 142, a GPS A band cutoff filter 144 is included. The first power supply terminal 114, the GPS band matching circuit 130, the GPS band pass filter 132, and the first LNA 134 are the same as those in FIG. The ITS / DTV band cutoff filter 140 is connected between the ITS / DTV band cutoff filter 140 and the coaxial cable 80. The ITS / DTV band cut-off filter 140 cuts off the ITS / DTV band.

  The second power supply terminal 118 and the ITS / DTV band matching circuit 136 are the same as those in FIG. A low-pass filter 142 and a GPS band cutoff filter 144 are connected in series between the ITS / DTV band matching circuit 136 and the coaxial cable 80. The low-pass filter 142 passes a low-frequency component, and the GPS band blocking filter 144 blocks a GPS band signal. The coaxial cable 80 transmits a GPS band signal, an ITS band signal, and a DTV band signal.

  According to the present embodiment, ITS / DTV and GPS can be transmitted to the in-vehicle terminal device with one coaxial cable 80. Also, since only one coaxial cable 80 is used, installation can be facilitated.

(Example 5)
The fifth embodiment relates to an antenna provided on a transparent film and installed in a vehicle, and more particularly to a circuit board connected to the antenna according to the second or third embodiment. In Example 2 or 3, another coaxial cable is used for GPS and ITS / DTV. Moreover, in Example 4, one coaxial cable is used for GPS and ITS / DTV. When the power of a signal received by the DTV is small, it is desirable to amplify the received signal before transmitting it to the coaxial cable. On the other hand, transmission and reception are performed in ITS, but only reception is performed in DTV. When the same coaxial cable is used for ITS / DTV, the received signal is transmitted to the coaxial cable. It cannot be amplified before it is made. In order to cope with this, in Example 5, another coaxial cable is used for DTV and GPS / ITS. With such a configuration, it is possible to amplify the DTV reception signal before transmitting it to the coaxial cable. Here, it demonstrates centering on the difference from before.

  FIG. 14 is a front view of a circuit board 110 according to the fifth embodiment of the present invention. The circuit board 110 includes a ground 112, a first power supply terminal 114, a GPS band matching circuit 130, a GPS band pass filter 132, a first LNA 134, an ITS / DTV band cutoff filter 140, a second power supply terminal 118, and an ITS / DTV band matching circuit 136. , Low pass filter 146, second LNA 148, ITS band pass filter 150, and GPS band cut filter 144. The first power supply terminal 114, the GPS band matching circuit 130, the GPS band pass filter 132, the first LNA 134, and the ITS / DTV band cutoff filter 140 are the same as those in FIG.

  The second power supply terminal 118 and the ITS / DTV band matching circuit 136 are the same as those in FIG. Similar to the first LNA 134, the second LNA 148 is an LNA. A low-pass filter 146 and a second LNA 148 are connected in series between the ITS / DTV band matching circuit 136 and the second coaxial cable 84. The low-pass filter 146 passes a low-frequency component below the DTV band, and the second LNA 148 amplifies the signal. The second coaxial cable 84 transmits a DTV band signal. The ITS / DTV band matching circuit 136 is also connected in series with an ITS band pass filter 150 and a GPS band cutoff filter 144. The ITS band pass filter 150 passes the ITS band signal, and the GPS band blocking filter 144 blocks the GPS band signal. The first coaxial cable 82 transmits a GPS band signal and an ITS band signal.

  According to the present embodiment, the signal can be amplified by the LNA before passing through the coaxial cable having a large loss with respect to the DTV as the receiving system. Further, since the signal is amplified, the sensitivity of the DTV can be improved.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In Examples 2 to 5 of the present invention, the 1.575 GHz band and the 470 MHz to 765 MHz band are used. However, the present invention is not limited to this, and other frequency bands may be used, for example. Therefore, it may be used for wireless communication systems other than GPS and ITS, for example, mobile phone systems, radio broadcasts, terrestrial digital broadcasts, VICS (registered trademark) (vehicle information and communication system), and ETC (electronic toll collection system). . According to this modification, the antenna 20 according to this embodiment can be applied to various wireless communication systems.

  In the second to fourth embodiments of the present invention, the antenna 20 is used for GPS, ITS, and DTV. However, the present invention is not limited to this, and the antenna 20 may be used for two of these. Specifically, the antenna 20 may be used for a combination of GPS and ITS or a combination of GPS and DTV. According to this modification, the degree of freedom of configuration can be improved.

  The outline of one embodiment of the present invention is as follows. An antenna device according to an aspect of the present invention includes a radiating element, a ground element that is spaced apart from one end side of the radiating element and disposed substantially orthogonal to the radiating element, and is spaced from the other end side of the radiating element. And a parasitic element that is arranged substantially orthogonally. The parasitic element is electrically connected to the radiating element.

  According to this aspect, the ground element is arranged substantially orthogonal to the radiating element, spaced from one end side of the radiating element, and the parasitic element is arranged substantially orthogonal to the radiating element, separated from the other end side of the radiating element. Therefore, stable characteristics can be realized even if matching is unnecessary.

  The parasitic element may be disposed to face the ground element. In this case, the antenna can be downsized.

  An additional radiating element and an additional ground element that is spaced apart from one end side of the additional radiating element and that is at least partially disposed substantially orthogonal to the additional radiating element may be further provided. The additional radiating element and the additional ground element may be disposed on the outer periphery of the radiating element, the ground element, and the parasitic element. In this case, a plurality of bands can be handled.

  The ground element and the additional ground element may be integrally formed. In this case, the configuration can be simplified.

  The radiating element, the ground element, the parasitic element, the additional radiating element, and the additional ground element may be formed of a transparent conductive material having a light transmittance of 80% or more. In this case, visibility can be improved.

  A first power supply terminal provided in the radiating element, a second power supply terminal provided in the additional radiating element, and a ground terminal provided in the ground element are further provided.

  A first filter connected to the second power supply terminal and blocking the first frequency; and a second filter connected to the first power supply terminal and blocking a second frequency different from the first frequency. These filters may be further provided.

  20 antenna, 22 first radiating element, 24 first ground element, 26 parasitic element, 28 first feeding pad, 30 ground pad, 38 transparent film.

Claims (7)

A radiating element;
A ground element that is spaced from one end side of the radiating element and is substantially orthogonal to the radiating element;
A parasitic element spaced apart from the other end side of the radiating element and disposed substantially orthogonal to the radiating element;
The antenna device, wherein the parasitic element is electrically connected to the radiating element.   The antenna device according to claim 1, wherein the parasitic element is disposed to face the ground element. An additional radiating element;
An additional ground element that is spaced apart from one end side of the additional radiating element and at least a part of which is substantially orthogonal to the additional radiating element;
The antenna device according to claim 1, wherein the additional radiating element and the additional ground element are arranged on an outer periphery of the radiating element, the ground element, and the parasitic element.   The antenna device according to claim 3, wherein the ground element and the additional ground element are integrally formed.   The radiating element, the ground element, the parasitic element, the additional radiating element, and the additional ground element are formed of a transparent conductive material having a light transmittance of 80% or more. 5. The antenna device according to 4. A first power supply terminal provided in the radiating element;
A second power supply terminal provided in the additional radiating element;
The antenna device according to claim 3, further comprising a ground terminal provided on the ground element. A first filter connected to the second power supply terminal and blocking a first frequency;
The antenna apparatus according to claim 6, further comprising a second filter connected to the first power supply terminal and blocking a second frequency different from the first frequency.

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