Abstract:
A loop antenna providing a reception performance equivalent to a patch antenna receiving a circularly polarized wave, simple in configuration, and kept low in cost, which forms a loop element and a parasitic element provided independently of this loop element on the same dielectric board to form an antenna element and sends or receives a circularly polarized wave by this antenna element, provides a metal plate parallel with or having a slight inclination with respect to the dielectric board, and sets this metal plate separated from the dielectric board by exactly a predetermined distance.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims priority from, and incorporates by reference the entire disclosures of, Japanese Patent Application (1) No. 2005-095516, filed on Mar. 29, 2005 and (2) No. 2006-029953, filed on Feb. 7, 2006. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a loop antenna, more particularly relates to a loop antenna able to obtain a reception performance of a circularly polarized wave equivalent to that of a patch antenna, by a simple configuration. The loop antenna of the present invention can be applied to an antenna system provided with an electronic apparatus connected with this antenna by a cable and to a vehicle mounting an antenna system able to obtain a reception performance of a circularly polarized wave equivalent to that of a patch antenna by installing this antenna system at a dielectric part of the vehicle. 
   2. Description of the Related Art 
   In the past, automobiles and other vehicles (moving bodies) have been equipped with antennas enabling the reception of radio waves even during movement. In general, the radio waves received by a vehicle have principally been the medium waves (MW) for AM radio and the very high frequency (VHF) or ultrahigh frequency (UHF) waves for FM radio or television. 
   However, in recent years, in addition to antennas receiving these radio waves, antennas for global positioning systems (GPS), antennas for receiving satellite waves of satellite digital broadcasts or their reradiated waves (gap filler waves), antennas for receiving waves for conversation over car phones, mobile phones, etc., and other antennas have become increasingly required for vehicles. Further, antennas for sending and receiving radio waves to and from parts of intelligent traffic systems (ITS) such as electronic toll collectors (automatic toll systems) for automatically collecting tolls on highways and toll roads and radio wave beacons of vehicle information communication systems (VICS) providing road traffic information have become necessary. Therefore, recent vehicles have had to mount antennas for receiving and sending a large number of types of radio waves (media). 
   Among the radio waves sent from and received by these moving bodies, the GPS waves, satellite digital broadcast waves, and electronic toll collector waves are a circularly polarized wave. Further, for conventional a circularly polarized wave antennas, patch antennas have usually been used. Among these patch antennas, ones comprised of ceramic or other dielectric boards on one surface of which planar ground conductors are laid and on the other surface of which radiating conductors are laid have often been employed. As this type of patch antenna, a low profile patch antenna for moving bodies used on the roofs of automobile and other moving bodies, that is, a low profile moving body use patch antennas, has been employed (for example, see Japanese Patent Publication (A) No. 2002-135045, FIG. 1 and FIG. 3). 
   However, the patch antenna disclosed in Japanese Patent Publication (A) No. 2002-135045 etc. is comprised of two types of dielectric boards superposed over each other and is formed with power parts passing through the boards, so there were the problems that the structure was complicated and the cost was high. As a result, the antenna system connecting a patch antenna disclosed in Japanese Patent Publication (A) No. 2002-135045 to an electronic apparatus by cables also became high in cost. Further, a vehicle mounting a patch antenna disclosed in Japanese Patent Publication (A) No. 2002-135045 etc. suffered from the problem of poor appearance due to the use of the patch antenna provided on the roof. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a loop antenna providing a reception performance equivalent to a patch antenna receiving a circularly polarized wave, requiring use of only a single dielectric board, and able to be kept down in cost. 
   To achieve this object, the loop antenna of the present invention is a loop antenna having an antenna element comprised of a loop element and parasitic element provided independent of the loop element and transmitting or receiving a circularly polarized wave, wherein the antenna element is formed on a single surface, and a conductor surface parallel with or having a slight inclination from the surface is provided near the surface. 
   Such a loop antenna can be configured as follows:
         1) The conductor surface is comprised of wire conductors arranged in a mesh.   2) The antenna element is formed on one surface of a dielectric board or at a certain layer of a member forming a dielectric board, while the conductor surface is formed on the other surface of this dielectric board or at another layer than that certain layer of the member forming the dielectric board. The dielectric board in this case may be made a dielectric member provided in a vehicle.   3) The antenna element and conductor surface may be provided on different dielectric boards. In this case, the conductor surface may be made a conductor forming part of the chassis of the vehicle, a conductor forming part of equipment provided in the vehicle, or a conductor attached to the vehicle. On the other hand, part of the member forming the conductor surface may be extended in the direction of the dielectric member forming the antenna element and this extended part used to support the dielectric member.   4) The conductor pattern of the antenna element is formed on a dielectric board, while the same board is formed with a circuit connecting to the loop element of the antenna element. In this case, the circuit may also be arranged inside the loop of the loop element. Further, outside of the circuit, two loop elements with different loop diameters may be formed doubly without overlap.   5) A power part formed on a surface separate from the surface where the antenna element is provided, a conducting means connecting the antenna element and the power part, a mesh ground pattern formed on the surface of the dielectric where the power part is provided, and a driven circuit part provided to contact the power part are provided. In this case, the dielectric may be a dielectric member forming part of a vehicle.       

   Further, the loop antenna of the present invention may be applied to an antenna system provided with an electronic apparatus connected to the loop antenna by a cable. This antenna system is an antenna system comprised of a loop antenna having an antenna element comprised of a loop element and a parasitic element provided independently of the loop element and sending or receiving a circularly polarized wave, an electronic apparatus processing a signal sent or received by the loop antenna, and a cable connecting the loop antenna and the electronic apparatus, wherein the antenna element is formed on one surface and a conductor surface parallel to that surface or having a slight inclination is provided near that surface. 
   Further, the loop antenna of the present invention can be applied to a vehicle mounting an antenna system providing a loop antenna at a dielectric part of the vehicle so as to obtain a reception performance of a circularly polarized wave equivalent to that of a patch antenna. That is, the present invention provides a vehicle equipped with an antenna system comprised of a loop antenna having an antenna element comprised of a loop element and a parasitic element provided independently of the loop element and sending and receiving a circularly polarized wave, an electronic apparatus for processing a signal sent or received by the loop antenna, and a cable connecting the loop antenna and electronic apparatus, wherein the antenna element is formed at a dielectric member of the vehicle and a conductor surface parallel to that antenna or having a slight inclination is provided near the antenna element. 
   As explained above, according to the loop antenna of the present invention, there are the effects that a circularly polarized wave antenna requiring use of only a single dielectric board, able to be kept down in cost, and providing a reception performance equivalent to a patch antenna, an antenna system using that antenna, and a vehicle mounting this antenna system can be realized. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which like references indicate similar elements. Note that the following figures are not necessarily drawn to scale. In the figures, 
       FIG. 1A  is a sectional view showing the configuration of a conventional patch antenna; 
       FIG. 1B  is a sectional view of the configuration of an embodiment of the loop antenna of the present invention; 
       FIG. 1C  is a plan view showing the shape and size of an antenna element of the patch antenna of  FIG. 1A ; 
       FIG. 1D  is a plan view showing the shape and size of an antenna element of the loop antenna of the present invention; 
       FIG. 2A  is a perspective view showing an example of arrangement of the antenna element of the loop antenna shown in  FIG. 1B  and a low noise amplifier on a dielectric board; 
       FIG. 2B  is a perspective view showing an example of a pattern on a back surface of the dielectric board shown in  FIG. 2A ; 
       FIG. 2C  is a perspective view showing another example of a pattern on a back surface of the dielectric board shown in  FIG. 2A ; 
       FIG. 3A  is a perspective view showing another example of the antenna element of the loop antenna shown in  FIG. 2A  and a ground pattern on the bottom surface of the dielectric board of a low noise amplifier; 
       FIG. 3B  is a perspective view of the dielectric board shown in  FIG. 3A  as seen from the back surface; 
       FIG. 3C  and  FIG. 3D  are perspective views of other examples of patterns on the back surface of the dielectric board shown in  FIG. 3B ; 
       FIG. 3E  is a side sectional view of an embodiment where the antenna element is formed on a film; 
       FIG. 3F  is a side sectional view showing a modification of the embodiment where the antenna element is formed on a film; 
       FIG. 3G  is a side sectional view showing an embodiment where the antenna element is buried in a dielectric board; 
       FIG. 4A  is a perspective view showing the positional relationship between the dielectric board shown in  FIG. 1B  and a metal plate; 
       FIG. 4B  is a perspective view showing an embodiment where the metal plate of  FIG. 4A  is replaced by a metal housing of an electronic apparatus; 
       FIG. 5  is a perspective view showing an embodiment where the metal plate shown in  FIG. 4A  is replaced by a dielectric board provided with a ground pattern; 
       FIG. 6A  is a side view of an example of fastening the dielectric board shown in  FIG. 4A  and a metal plate by L-shaped fastenings; 
       FIG. 6B  is a side view of an example of fastening the dielectric board shown in  FIG. 4B  and a metal housing of an electronic apparatus by L-shaped fastenings; 
       FIG. 6C  is a perspective view showing the configuration of an L-shaped fastening used in  FIGS. 6A and 6B ; 
       FIG. 6D  is a perspective view showing an embodiment of a gate-type fastening; 
       FIG. 6E  is a side view showing the state of using the gate-type fastening of  FIG. 6D  to fasten the dielectric board shown in  FIG. 5A  to a metal plate or a dielectric; 
       FIG. 6F  is a perspective view of a metal plate showing an embodiment of forming attachments at the metal plate itself; 
       FIG. 7A  is a sectional view of principal parts of an automobile showing an example of providing a dielectric board on which the loop antenna of the present invention is set above part of the frame inside an automobile instrument panel; 
       FIG. 7B  is a perspective view showing the configuration of an example of a bracket in the case of attaching a dielectric board on which the loop antenna of the present invention is provided at the position shown by the broken line in  FIG. 7A ; 
       FIG. 7C  is a sectional view of principal parts of an automobile showing an example of providing a dielectric board on which the loop antenna of the present invention is set on top of a metal housing of an electronic apparatus provided inside an automobile instrument panel; 
       FIG. 8  is a view of another embodiment of the arrangement of the antenna element of the loop antenna of the present invention and a low noise amplifier on a dielectric board; 
       FIG. 9  is a view of a modification of the arrangement of the antenna element of the loop antenna of the present invention and the low noise amplifier on the dielectric board shown in  FIG. 8  and shows the arrangement of two types of antenna elements of a loop antenna and a low noise amplifier on a dielectric board; 
       FIG. 10A  is a perspective view showing an embodiment where a dielectric board on which the loop antenna of the present invention is provided is provided with a loop antenna separate from the other antenna on so as to form an integrated antenna; 
       FIG. 10B  is a view of the circuit configuration in the case of connecting the integrated antenna shown in  FIG. 10A  to a receiver and transmitter; 
       FIG. 11A  is a partial perspective view of an embodiment in which the loop antenna of the present invention is provided on an automobile front windshield; 
       FIG. 11B  is a partial sectional view of a part of a front windshield of  FIG. 11A  at which the loop antenna is provided; 
       FIG. 12A  is a perspective view showing an embodiment of connection with a connector in the case of forming the loop antenna of the present invention in an automobile front windshield; 
       FIG. 12B  is a perspective view showing another embodiment of connection with a connector in the case of forming the loop antenna of the present invention in an automobile front windshield; 
       FIG. 12C  is a sectional view showing the configuration of the connector of  FIG. 12B ; 
       FIG. 13A  is a plan view showing the internal configuration of the connector of  FIG. 12A ; 
       FIG. 13B  is a side view of the connector of  FIG. 13A ; and 
       FIG. 14  is a partial perspective view of an automobile showing an embodiment of providing the loop antenna of the present invention at the plastic body of an automobile. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Below, the attached drawings will be used to explain embodiments of the loop antenna of the present invention based on specific embodiments. 
   First, the loop antenna of the present invention will be explained compared with a conventional patch antenna.  FIG. 1A  shows the structure of a conventional patch antenna  25 . The patch antenna  25  is, in general, as shown in  FIG. 1A , comprised of a dielectric board  27  on the top surface of which an antenna pattern (patch element)  28  is provided and on the bottom surface of which a ground pattern  29  is provided. The dielectric board  27  is comprised of a ceramic member with a high relative dielectric constant. In this example of a patch antenna  25 , an amplifier  30  is provided under the ground pattern  29  of the dielectric board  27 . The amplifier  30  is comprised of a dielectric board  31  on one surface of which a ground pattern  32  is formed and on the other surface of which an amplifier circuit pattern  33  is formed. The amplifier  30  is arranged with the ground pattern  32  superposed over the ground pattern  29  of the patch antenna  25 . 
   Further, when a power use coaxial cable  22  is connected to the amplifier  30  side of the patch antenna  25 , a power pin  8  connected to the patch element  28  is provided passing through the amplifier  30  and dielectric board  27 . The other end of the power pin  8  connected to the patch element  28  at one end is soldered at the amplifier circuit pattern  33  of the amplifier  30 . In this case, the coaxial cable  22  is connected at its center conductor  22   a  to the amplifier circuit pattern  33  by soldering, while is connected at its external conductor  22   b  to the ground pattern  34  on the amplifier circuit pattern  33  by soldering. Usually, this patch antenna  25  is accommodated in a plastic housing. 
   The patch element  28  is designed to be able to receive a circularly polarized wave sent from a GPS satellite. When the wavelength of the reception frequency is λ, as shown in  FIG. 1C , it is provided with a λ/2-sided square antenna element. When the patch element  28  receives a relatively low frequency like a wave from a GPS satellite, a high dielectric constant board may be used to reduce the size. 
   As opposed to this, the loop antenna  10  of the present invention able to receive a circularly polarized wave is accommodated in a dome-shaped plastic container  16 . The dome-shaped container  16  is provided inside it with a ring-shaped holding projection  17  parallel to the floor. The dielectric board  11  is placed on the holding projection  17 . The dielectric board  11  is provided on its front surface with the antenna element  12  and a low noise amplifier (LNA)  13  connected to this antenna element  12 . The low noise amplifier  13  has a coaxial cable  22  provided with a center conductor  22   a  and an external conductor  22   b  connected to it. On the other hand, the dielectric board  11  is provided on its back surface at the opposite side from the low noise amplifier  13  with a ground pattern  14 . This ground pattern  14  is for example a mat pattern and is provided on the dielectric board  11  at the part under the low noise amplifier  13 . 
   Further, the dome-shaped container has a metal plate  15  laid at its floor. The metal plate  15  is separated from the antenna element  12  by exactly a predetermined distance. By providing this metal plate  15 , the metal plate  15  acts as a reflector and improves the reception performance with respect to waves arriving from the side directions of the dome. In the loop antenna  10  of this embodiment, the antenna element  12  is designed to receive a circularly polarized wave sent from a GPS satellite and, as shown in  FIG. 1D , is comprised of a λ/4-sided square loop element  12 A. Further, near this square loop element  12 A, a parasitic element  12 B not contacting the loop element  12 A is provided. 
   The loop antenna  10  of this embodiment, being configured in the above way, can be made smaller in the antenna element  12  compared with the conventional patch antenna  25  explained with reference to  FIG. 1A  and  FIG. 1C , so can be made smaller in size. 
     FIG. 2A  shows an example of the arrangement of the antenna element  12  (loop element  12 A and parasitic element  12 B) of the loop antenna  10  shown in  FIG. 1B  and the low noise amplifier  13  on the dielectric board  11 . One of the loop element  12 A provided on one surface of the dielectric board  11  is connected to the low noise amplifier  13 , while the other end passes through the dielectric board  11  and is connected to the ground pattern  14  provided on the other surface of the dielectric board  11  (bottom surface). The dielectric board  11  can be made a transparent glass plate. 
   The ground pattern  14 , in this embodiment, is provided at a region of about half of the bottom surface of the dielectric board  11  (low noise amplifier  13  side). However, the ground pattern  14  may also be provided extended to the part directly under the antenna element  12 . 
   Further, the ground pattern  14  is usually a mat pattern, but a mesh conductor  14 A of the pattern shown in  FIG. 2B  or a mesh conductor  14 B of the pattern shown in  FIG. 2C  may also be used instead of the ground pattern  14 . The mesh should have a pitch of λ/10 or so. The distance between the metal plate  15  and the antenna element  12  in the thickness direction of the dielectric board  11  is ideally λ/4. 
   Note that the ground pattern  14  provided at the bottom surface of the dielectric board  11  shown in  FIG. 2A , as shown in  FIG. 3A , may also be provided at the entire bottom surface of the dielectric board  11 . In this case, the ground pattern  14  extended to directly under the antenna element  12  also serves as the metal plate  15  shown in  FIG. 1B . The ground pattern  14  provided at the entire bottom surface of the dielectric board  11  may also be made the mat pattern shown in  FIG. 3B . Further, it may also be made the mesh conductor  14 A of the pattern shown in  FIG. 3C  or mesh conductor  14 B of the pattern shown in  FIG. 3D . 
   Further, the antenna element  12 , as shown in  FIG. 3E , may be attached to a dielectric board  11  as a film loop antenna  10 A comprised of a sheet-like transparent film  21  on which an antenna element  12  is formed. Instead of this film loop antenna  10 A, as shown in  FIG. 3F , it is also possible to use a film loop antenna  10 B comprised of a sheet-like transparent film  21  formed with a ground pattern  26  on the surface on which the antenna element  12  is not formed. 
   Further, the antenna element  12 , as shown in  FIG. 3G , may be formed embedded in the dielectric board  11 . In this case, the antenna element  12  and the low noise amplifier  13  should be connected by a via  24 . Further, the ground pattern  14  may be formed by a transparent member and may be formed by a transparent member on a transparent sheet. 
   Note that in the case of the embodiment of  FIG. 3F , the dielectric board  11  and the ground pattern  14  become close in distance, so if the ground pattern  14  is provided only under the low noise amplifier  13  as shown in  FIG. 1B , the loop antenna is improved in performance in some cases. 
     FIG. 4A  shows the positional relationship between the dielectric board  11  and metal plate  15  shown in  FIG. 1B . In this embodiment, the mesh conductor  14 B is provided as the ground pattern at the region of about half of the bottom surface of the dielectric board  11  (low noise amplifier  13  side). Further, there is a predetermined distance H between the dielectric board  11  and the metal plate  15 . 
     FIG. 4B  shows an embodiment where the metal plate  15  of  FIG. 4A  is replaced by a metal housing  2  of an electronic apparatus  1 . The electronic apparatus  1  is for example a car navigation system or audio system mounted in the automobile. In this case as well, a predetermined distance H is provided between the metal housing  2  of the electronic apparatus  1  and the dielectric board  11 . Note that instead of the metal plate  15  shown in  FIG. 5  and  FIG. 3A , it is also possible to use a dielectric board  18  of the same size as the metal plate  15  over the entire surface of which the ground pattern  19  is provided. 
     FIG. 6A  shows an example of a method of separating the dielectric board  11  and metal plate  15  shown in  FIG. 4A  by exactly a predetermined distance H. To separate the dielectric board  11  and the metal plate  15  by exactly a predetermined distance H, it is sufficient to fasten the two ends of the dielectric board  11  over the dielectric board  11  separated from the dielectric board  11  by exactly a predetermined distance H using the L-shaped attachments  3  shown in  FIG. 6C . 
     FIG. 6B  shows an example of fastening the dielectric board  11  above the metal housing  2  of the electronic apparatus  1  shown in  FIG. 4B  by the L-shaped attachments  3 . These L-shaped attachments  3  may be made of metal or plastic. Further, the L-shaped attachments  3  and the dielectric board  11 , metal plate  15 , or metal housing  2  of the electronic apparatus  1  may be joined by screws or an adhesive. 
   Further, rather than fastening L-shaped attachments  3  on the metal plate  15 , as shown in  FIG. 6F , parts of the metal plate  15  may be cut and bent upward to the dielectric board  11  side in shapes similar to the above-mentioned L-shaped attachments  3  so as to form extended parts  15 E and these extended part  15 E used to support the dielectric board  11 . 
   On the other hand, the dielectric board  11  and metal plate  15  or the dielectric board  11  and metal housing  2  of the electronic apparatus  1  may be connected using a gate-type attachment  4  shown in  FIG. 6D .  FIG. 6E  shows the state of using the gate-type attachment  4  to fasten the dielectric board  11  on the metal housing  2  of the electronic apparatus  1  shown in  FIG. 4B . The gate-type attachment  4  in the case may be made of plastic or metal. 
     FIG. 7A  shows an embodiment where the dielectric board  11  provided with the loop antenna  10  of the present invention is placed above the part of the chassis frame  7  inside the instrument panel of the automobile  5 . Since the chassis frame  7  is metal, this chassis frame  7  can be used instead of the above-mentioned metal plate  15 . Further, it is possible to fasten a metal bracket  9  shown in  FIG. 78  at a position shown by the broken line at the side face of the metal chassis frame  7  and place the dielectric board  11  provided with the loop antenna  10  of the present invention over this. 
     FIG. 7C  shows an embodiment where the dielectric board  11  provided with the loop antenna  10  of the present invention is placed above the metal housing of the electronic apparatus  1  provided at the instrument panel of the automobile  5  etc. In this way, in the present invention, when providing the loop antenna  10  inside the instrument panel of the automobile  5 , it is possible to use a metal member inside the instrument panel instead of the metal plate  15  shown in  FIG. 1B . 
     FIG. 8  shows another embodiment of provision of the antenna element  12  (loop element  12 A and parasitic element  12 B) of the loop antenna  10  of the present invention and the low noise amplifier  13  on the dielectric board  11 . In the above-mentioned embodiments, the low noise amplifier  13  was provided outside the loop of the loop element  12 A of the loop antenna  10 . On the other hand, in this embodiment, the low noise amplifier  13  is provided inside the loop element  12 A of the loop antenna  10 . Even if providing the low noise amplifier  13  inside the loop of the loop element  12 A of the loop antenna  10 , there is no effect on the reception performance of the loop antenna  10 , the dielectric board  11  can be made smaller in size, and in turn the loop antenna  10  can be made smaller in size. In this case, the ground pattern can be made the same rectangular shape as the low noise amplifier  13  (same shape and same size). 
     FIG. 9  shows a modification of the provision of the antenna element  12  (loop element  12 A and parasitic element  12 B) of the loop antenna  10  of the present invention and the low noise amplifier  13  on the dielectric board  11  shown in  FIG. 8 . In the embodiment shown in  FIG. 8 , only one type of loop antenna  10  was provided on the dielectric board  11 , but in this embodiment, in addition to the loop antenna  10 , another loop antenna  40  is provided on the dielectric board  11 . 
   The antenna element  42  of the loop antenna  40 , like the loop antenna  10 , is provided with a loop element  42 A and a parasitic element  42 B, but the low noise amplifier  13  is used in common with the loop antenna  10 . The loop antenna  40  is for receiving a circularly polarized wave of a frequency lower than the loop antenna  10 . Note that in this embodiment, the parasitic element  12 B is positioned differently from  FIG. 8 , but even if the parasitic element is provided at a position rotated 180 degrees about the center of the loop of the loop antenna, the function is the same. Further, by using the low noise amplifier  13  in common for the loop antennas  10  and  40 , it is possible to reduce the cost and make the antenna smaller. In this case, the ground pattern can be made the same rectangular shape as the low noise amplifier  13  (same shape and same size). 
     FIG. 10A  shows an embodiment where the dielectric board  11  provided with the loop antenna  10  of the present invention is provided with a loop antenna  50  separate from the other antenna (monopole antenna)  20  so as to form an integrated antenna  100  on the dielectric board  11 . The loop antenna  10  receives waves from a GPS satellite and, in the same way as the above-mentioned embodiment, is provided with an antenna element  12  comprised of a loop element  12 A and parasitic element  12 B and a low noise amplifier  13 . Further, the output of the low noise amplifier  13  is input to a combiner/distributor  70 . The monopole antenna  20  is a VICS antenna and is directly connected to the combiner/distributor  70 . Further, the loop antenna  50  is an electronic toll collector antenna and is provided with an antenna element  52  comprised of a loop element  52 A and parasitic element  52 B. One end of the loop element  52 A is connected to the ground pattern  14 B provided at the bottom surface of the dielectric board  11 , while the other end is directly connected to the combiner/distributor  70 . 
     FIG. 10B  shows the circuit configuration in the case of connecting the integrated antenna  100  shown in  FIG. 10A  to the receiver/transmitter  80 . The wave received by the GPS loop antenna  10  is amplified by the low noise amplifier  13 , then input to the combiner/distributor  70 , passed through a filter  71 , then combined. The wave received by the VICS monopole antenna  20  is input to the combiner/distributor  70 , passed through a filter  72 , then combined. The wave received by the electronic toll collector loop antenna  50  is input to the combiner/distributor  70 , passed through the filter  73 , then combined. 
   The signal combined at the combiner/distributor  70  of the integrated antenna  100  is led by the coaxial cable  22  to the combiner/distributor  80  housed in the receiver/transmitter  60 . The combined signal is distributed at the combiner/distributor  80 , passed through the filters  81 ,  82 , and  83 , and input to the GPS receiver  84 , VICS receiver  85 , and electronic toll collector receiver  86  for processing. As the receiver/transmitter  60 , for example, there is a navigation system. 
     FIG. 11A  shows an example where the loop antenna  10  of the present invention is attached to the front windshield  90  of the automobile  5 . The loop antenna  10  is kept from interfering with the field of vision of the driver by being provided at the bottom of the front windshield  90 . The loop antenna  10  includes the loop element  12 A and the parasitic element  12 B. The mesh ground pattern (mesh wire)  44  is provided further inward toward the passenger compartment than these elements. 
     FIG. 11B  shows a cross-section of the location of the front windshield  90  shown in  FIG. 11A  where the loop antenna  10  is provided. The front windshield  90  is comprised of laminated glass including outside glass  91 , a resin sheet  92 , and inside glass  93 . The antenna element and the parasitic elements  12 A,  12 B are formed in the intermediate resin sheet  92 . Further, the mesh wire  44  is formed at the inside of the inside glass  93  (inside the compartment). The antenna element  12 A formed at the resin sheet  92  is led out by wires  35  to the passenger compartment side of the inside glass  93  and connected to a connector  95  at connection terminals  96  and  97 . 
     FIG. 12A  shows an embodiment of connection of the front windshield  90  of the automobile provided with the loop antenna  10  of the present invention and the connector  95 . The front windshield  90  of this embodiment is comprised of laminated glass including outside glass  91 , a resin sheet  92 , and inside glass  93 . The ends in the lateral direction are formed with step differences  94 . The loop antenna  10  of the present invention is embedded in part of the resin sheet  92  in advance at the stage of production of the front windshield  90 . The two ends of the loop element  12 A are led out by wires  35  to a step difference  94  of the front windshield  90 . Further, the wires  35  are bent to the inside glass  93  side at the step difference  94  and are connected to the connection terminals  36  and  37  provided at the surface of the passenger compartment side of the inside glass  93 . 
   The resin sheet  92  has transparency to secure visibility. Note that it is also possible not to provide the resin sheet  92  and to just provide the antenna elements  12 A and  12 B between the outside glass  91  and inside glass  92 . Further, around the loop antenna  10  (surface at passenger compartment side of inside glass  93 ), as illustrated, metal mesh wire  44  is provided instead of the metal plate. When using a transparent conductor as the metal plate, it is possible to use a mat pattern, but if using a usual metal, with a mat pattern, the driver would not be able to see through it, so mesh wire  44  is used instead of the metal plate to improve the visibility through the glass. Further, the mesh wire  44  may be formed by a transparent conductor so as to further improve the visibility. 
   The connector  95  for connecting with the connection terminals  36  and  37  provided at the inside compartment side of the inside glass  93  is provided with a plastic housing provided with connection terminals  96 ,  97  having springiness. Inside the connector  95 , as shown in  FIGS. 13A and 13B , the dielectric board  11  is housed. Above this dielectric board  11  is the low noise amplifier  13 . The coaxial cable  22  is connected to the low noise amplifier  13 , while the connection terminals  96 ,  97  with springiness are connected by through holes  23  to the low noise amplifier  13 . Further, this connector  95  is attached by two-sided adhesive tape, adhesive, or other means to the front windshield  90  so that the connection terminals  96 ,  97  are connected to the connection terminals  36 ,  37  on the inside glass  93 . 
     FIG. 12B  shows another embodiment of connection with the connector  95  when forming the loop antenna  10  of the present invention at the front windshield  90  of an automobile. The front windshield  90  of this embodiment is also comprised of a laminate of outside glass  91 , a resin sheet  92 , and inside glass  93 . Its lateral direction ends are formed with step differences  94 . The loop antenna  10  of the present invention is embedded in advance in part of the resin layer  92  at the stage of production of the front windshield  90 . The two ends of the loop element  12 A are led out by wires  35  to a step difference  94  of the front windshield  90 . Further, the wires  35  are bent at the step difference  94  to the inside glass  93  side and are connected to connection projections  38 ,  39  provided at the inside compartment side of the inside glass  93 . Further, around the loop antenna  10 , as illustrated, the metal mesh wire  44  is provided. 
   The connector  95  connecting to the connection projections  38 ,  39  provided at the inside compartment side of the inside glass  93  is provided with a plastic housing provided with connection terminals  98 ,  99  having springiness. The structure of the connector  95  is the same as the structure shown in  FIGS. 13A and 13B  except for the structure of the connection terminals  98 ,  99  having springiness. The connection terminals  98 ,  99 , as shown in  FIG. 12C , are both comprised of two springs facing each other. The connection projections  38 ,  39  are designed to be inserted between these springs while pushing them apart. The connector  95  may be attached to the front windshield  90  by a method the same as in the embodiment of  FIG. 13A  using two-sided adhesive tape, an adhesive, or other means. 
   Note that if providing a monopole antenna or another loop antenna adjoining a loop antenna  10  of the embodiment explained with respect to  FIG. 12A ,  12 B as shown in  FIG. 10A , an integrated antenna can be formed at the front windshield  90 . 
   Further, the loop antenna  10  of the present invention, as shown in  FIG. 14 , may also be attached to a plastic body panel  51  of a vehicle in addition to a dielectric member of the automobile  5  such as glass (front windshield  90 ). 
   Although only some exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciated that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.