Patent Publication Number: US-7710334-B2

Title: Complex antenna device

Description:
BACKGROUND 
   1. Technical Field 
   The present invention relates to a complex antenna device, and more particularly, to a complex antenna device in which a planar antenna and a bar antenna are combined. 
   2. Related Art 
   Currently, as known in this technical field, various antennas are mounted on a vehicle such as an automobile. As such an antenna, for example, an antenna for a GPS (Global Positioning System), an antenna for an SDARS (satellite digital audio radio service), an antenna for a radio telephone, or an antenna for AM/FM radio is used. 
   The GPS (Global Positioning System) is a satellite positioning system using artificial satellites. In the GPS system, electric waves (GPS signal) are received from four artificial satellites (hereinafter, referred to as “GPS satellite”) among twenty four GPS satellites orbiting around the earth, a positional relation and a time error between a mobile object and the GPS satellites are measured on the basis of the received electric waves, and a position or an altitude of the mobile object on a map is calculated with high precision on the basis of triangulation. 
   Recently, the GPS is used for a car navigation system detecting a position of a driving automobile and comes into wide use. The car navigation device includes a GPS antenna for receiving a GPS signal, a processor for detecting a present position of a vehicle by processing the GPS signal received by the GPS antenna, a displayer for displaying the position detected by the processor on a map, and the like. A planar antenna such as a patch antenna is used as the GPS antenna. 
   A rod antenna (bar antenna) is known as a 3-wave sharing antenna capable of receiving a radio telephone band, an FM radio band, and an AM radio band. The bar antenna is used as the radio telephone antenna or the AM/FM radio antenna. The bar antenna is made of metal. A multi-frequency antenna capable of receiving 4 waves of the radio telephone band, the FM radio band, the AM radio band, and a GPS band was proposed (e.g., see Patent Document 1). In the multi-frequency antenna disclosed in Patent Document 1, since a matching board is disposed upright on the base and an antenna element is inclined to the perpendicular line, a GPS satellite has a low elevation angle. However, the low elevation angle of the GPS satellite does not have a bad influence on the GPS antenna. 
   In addition, there was proposed a complex antenna in which a patch antenna capable of receiving a circular-polarized wave from the GPS satellite or the like and a rod antenna capable of sending and receiving a linearly-polarized wave used in a mobile telephone or the like are disposed in parallel to be a unit (e.g., see Patent Document 2). In the complex antenna disclosed in Patent Document 2, a direction of the power feeding patch relative to the rod antenna is set so that the short axis is substantially perpendicular to a plane that includes an intersection point of the short axis and a long axis of the power feeding patch of the patch antenna and an axis line of the rod antenna. Accordingly, it is suppressed that the electric wave radiated from the rod antenna has a bad influence on the adjacent patch antenna. 
   Further, an antenna device which is capable of receiving an electric wave signal radiated from a satellite and a terrestrial wave signal radiated from a terrestrial antenna and is suitable for a vehicle was proposed (e.g., see Patent Document 3). In the antenna device disclosed in Patent Document 3, a planar antenna is provided upwardly on a surface of a board and, a base end of an antenna element including a helical antenna departs from the planar antenna laterally, and a front end of the antenna element is inclined by about 30° about the vertical direction in the departing direction. 
   There is provided a 3-wave sharing antenna device in which an AM/FM receiving antenna capable of an AM broadcasting wave and an FM broadcasting wave and a GPS receiving antenna capable of receiving a GPS broadcasting wave are integrated with each other (e.g., see Patent Document 4). 
   The SDARS (Satellite Digital Audio Radio Service) is a digital broadcasting service using a satellite (hereinafter, referred to as “SDARS satellite”) in the United States. That is, in the United States, a digital radio receiver receiving a satellite wave or a terrestrial wave from the SDARS satellite to provide digital radio broadcasting has been developed and put in practical use. Currently, in the United States, two broadcasting stations of XM and Sirius have provided radio programs more than total 250 channels throughout the whole country. The digital radio receiver is generally mounted in a mobile object such as an automobile, receives the electric wave in the frequency band of about 2.3 GHz, and provides the radio broadcasting. That is, the digital radio receiver is a radio receiver capable of providing the mobile broadcasting. Since the frequency of the reception electric wave is about 2.3 GHz, the reception wavelength (resonance wavelength) λ at that time is about 128.3 mm. The terrestrial wave is formed in the manner that the satellite wave is received by an earth station, the frequency of the received satellite wave is slightly shifted, and the wave is re-sent in a linearly-polarized wave. That is, the satellite wave is a circular-polarized wave, but the terrestrial wave is a linearly-polarized wave. In addition, the planar antenna such as the patch antenna is used as the SDARS antenna. 
   The antenna device for XM satellite radio receives the circular-polarized electric wave from two geostationary satellites, and receives the electric wave by using terrestrial linear-polarized equipments in a blind zone. On the other hand, the antenna device for Sirius satellite radio receives the circular-polarized electric wave from three orbiting satellites (synchro type), and receives the electric wave by the use of the terrestrial linear-polarized equipments in the blind zone. 
   Since the electric wave in the frequency band of about 2.3 GHz is used in such digital radio broadcasting, an antenna device receiving the electric wave is required to be installed outdoors. Accordingly, when the digital radio receiver is mounted in a mobile object such as an automobile, the antenna device is required to be mounted on the roof of the mobile object. 
   Patent Document 1: JP-A-10-93327 
   Patent Document 2: JP-A-2003-309411 
   Patent Document 3: JP-A-10-107542 
   Patent Document 4: JP-A-8-335824 
   As described above, various complex antenna devices including plural kinds of antennas are known. In addition to the 3-wave sharing antenna (bar antenna) as the complex antenna device, it is conceivable that a planar antenna such as an SDARS antenna and a GPS antenna is mounted on a main surface of an antenna base. That is, a complex antenna in which a planar antenna and a bar antenna are combined is conceivable. However, in such a complex antenna, a ripple increases due to directivity (horizontal-plane directivity) of the planar antenna by physical influence of the bar antenna made of metal. That is, deterioration in ripple performance occurs due to the low elevation-angle property of the planar antenna. In other words, the bar antenna made of metal acts as a metallic obstacle when viewed from the planar antenna. 
   SUMMARY 
   An advantage of some aspects of the invention is to provide a complex antenna device capable of removing physical influence of a bar antenna on a planar antenna. The advantage can be attained by at least one of the following aspects: 
   According to a first aspect of the invention, there is provided a complex antenna device ( 10 ;  10 A;  10 B) comprising: an antenna base ( 20 ;  20 A) having a main surface ( 20   a ) and first and second ends ( 20   b ,  20   c ) opposed to each other; a bar antenna ( 30 ) including a metal body ( 31 ) disposed upright on a side of the first end of the antenna base ( 20 ;  20 A); at least one planar antenna ( 40 ,  50 ;  50 A) mounted on the main surface of the antenna base between the first and second ends of the antenna base; a metallic member ( 70 ;  70 A;  70 B) provided on a side of the second end of the antenna base so as to substantially remove physical influence of the bar antenna ( 30 ) on the planar antenna ( 50 ;  50 A). 
   In the complex antenna device ( 10 ) of the invention, the metallic member may include a metallic rod ( 70 ) disposed upright on the main surface ( 20   a ) of the antenna base. The complex antenna device ( 10 A) may include a top case made of resin and covering the bar antenna ( 30 ) and the planar antenna ( 40 ,  50 ) in cooperation with the antenna base ( 20 ). In this case, the metallic member may include a metallic tape ( 70 A) attached onto an inner wall ( 64   a ) of the top case. The complex antenna device ( 10 B) may include a top case ( 20 A) made of resin and covering the bar antenna and the planar antenna ( 50 A) in cooperation with the antenna base ( 20 A) made of metal. In this case, the metallic member ( 70 B) may include a screw boss of the antenna base disposed upright so as to attach the antenna base ( 20 A) to the top case ( 60 A). In addition, the metallic member ( 70 B) may further include a metallic screw ( 74 ) penetrating the screw boss ( 72 ). 
   In the complex antenna device ( 10 ;  10 A;  10 B) of the invention, the bar antenna ( 30 ) may be an antenna adapted to receive electric waves of AM/FM radio bands. Instead, the bar antenna ( 30 ) may be an antenna adapted to send and receive an electric wave for a car phone. The planar antenna ( 50 ;  50 A) may be an SDARS antenna adapted to receive an electric wave from an SDARS satellite. In addition, the at least one planar antennas may include a first planar antenna ( 40 ) adapted to receive an electric wave from a first satellite, and a second planar antenna ( 50 ) adapted to receive an electric wave from a second satellite. The first planar antenna ( 40 ) may be a GPS antenna adapted to receive an electric wave from a GPS satellite as the first satellite and the second planar antenna ( 50 ) may be an SDARS antenna adapted to receive an electric wave from an SDARS satellite as the second satellite. The GPS antenna ( 40 ) may be provided at a position close to the bar antenna and the SDARS antenna ( 50 ) may be provided at a position close to the metallic member ( 70 ;  70 A). 
   According to a second aspect of the invention, there is provided a complex antenna device comprising: an antenna base ( 20 ;  20 A); a bar antenna ( 30 ) made of metal; at least one planar antenna ( 40 ,  50 ;  50 A) mounted on the antenna base; a metallic member ( 70 ;  70 A;  70 B) made of metal, wherein the at least one planar antenna ( 40 ,  50 ;  50 A) is positioned between the bar antenna ( 30 ) and the metallic member ( 70 ;  70 A;  70 B) so as to substantially remove physical influence of the bar antenna ( 30 ) on the planar antenna ( 40 ,  50 ;  50 A). 
   In the complex antenna device ( 10 ) of the invention, the metallic member ( 70 ;  70 A;  70 B) includes a metallic rod ( 70 ) disposed upright on the antenna base. 
   In the complex antenna device ( 10 ) of the invention, the metallic member ( 70 ;  70 A;  70 B) includes a metallic tape ( 70 A) attached onto an inner wall of the antenna device ( 10 ). 
   Reference numerals in the parentheses are given to easily understand the invention, but are not limited thereto. 
   In the invention, since a metallic member is disposed on a side opposite to a bar antenna with a planar antenna interposed therebetween, physical influence of the bar antenna on the planar antenna can be removed. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
       FIGS. 1(A) and 1(B)  are diagrams illustrating a complex antenna device according to a first exemplary embodiment of the invention, in which  FIG. 1(A)  is a perspective view of a top case of the complex antenna device as obliquely viewed from the lower side and  FIG. 1(B)  is a perspective view of the complex antenna device with the top case detached therefrom, as obliquely viewed from the upper side. 
       FIGS. 2(A) to 2(F)  are diagrams illustrating a directive property of an SDARS antenna in the complex antenna device (the improved product) according to the invention with a metallic rod shown in  FIG. 1  and a directive property of an SDARS antenna in the known complex antenna device (the known product) without a metallic rod, and further illustrating directivity of an SDARS antenna in a case where a satellite wave from the SDARS satellite is received when the elevation angle of the SDARS satellite is in the range of 20° to 60°, in which  FIG. 2(A)  shows directivity when the elevation angle is 20°,  FIG. 2(B)  shows directivity when the elevation angle is 25°,  FIG. 2(C)  shows directivity when the elevation angle is 30°,  FIG. 2(D)  shows directivity when the elevation angle is 40°,  FIG. 2(E)  shows directivity when the elevation angle is 50°, and  FIG. 2(F)  shows directivity when the elevation angle is 60°. 
       FIG. 3  is a diagram illustrating a directive property of an SDARS antenna in the complex antenna device (the improved product) according to the invention with a metallic rod shown in  FIG. 1  and a directive property of an SDARS antenna in the known complex antenna device (the known product) without a metallic rod, and further illustrating directivity of an SDARS antenna in a case where a satellite wave from the SDARS satellite is received when the elevation angle is 0°. 
       FIGS. 4(A) and 4(B)  are diagrams illustrating a complex antenna device according to a second exemplary embodiment of the invention, in which  FIG. 4(A)  is a perspective view of a top case of the complex antenna device as obliquely viewed from the lower side and  FIG. 4(B)  is a perspective view of the complex antenna device with the top case detached, as obliquely viewed from the upper side. 
       FIG. 5  is a perspective view of a complex antenna device according to a third exemplary embodiment of the invention as viewed from the upper side. 
       FIG. 6  is a perspective view of the complex antenna device shown in  FIG. 5  as viewed from the lower side. 
       FIG. 7  is an exploded perspective view of the complex antenna device shown in  FIG. 5  with the antenna cover detached therefrom. 
       FIG. 8  is an exploded perspective view of the complex antenna device shown in  FIG. 5  as viewed from the lower side. 
   

   DESCRIPTION OF EXEMPLARY EMBODIMENTS 
   Hereinafter, exemplary embodiments of the invention will be described in detail with reference to the drawings. 
   A complex antenna  10  according to a first exemplary embodiment of the invention will be described with reference to  FIG. 1 .  FIG. 1(A)  is a perspective view of a top case  60  of the antenna device  10 , as obliquely viewed from the lower side.  FIG. 1(B)  is a perspective view of a complex antenna device  10  with the top case  60  detached therefrom, as obliquely viewed from the upper side. 
   The complex antenna device  10  includes an antenna base  20 , a bar antenna  30 , a first planar  40 , a second planar antenna  50 , and a top case  60  made of resin. 
   The antenna base  20  is made of die-casting materials such as zinc, aluminum, and magnesium. The antenna base  20  has a main surface  20   a , and a first end  20   b  and a second end  20   c  opposed to each other. The antenna base  20  has a substantially flat base portion  21  and first and second shield walls  22  and  23  formed on an upper surface (main surface  20   a ) of the base portion  21 . The base portion  21  and the first and second shield walls  22  and  23  are integrally formed. The first shield wall  22  is provided to shield a first low noise amplifier (LNA) circuit constituting a first planar antenna  40 . The second shield wall  23  is provided to shield a second low noise amplifier (LNA) circuit constituting a second planar antenna  50 . Although not shown in  FIG. 1(B) , a shield wall is further formed between the first shield wall  22  and the second shield wall  23 . 
   The bar antenna  30  is disposed upright at the first end  20   b  of the antenna base  20  and includes a metal  31 . A front end of the bar antenna  30  is provided obliquely in a direction departing from the first and second planar antennas  40  and  50 . In the exemplary embodiment, the bar antenna  30  serves as an antenna for receiving electric waves of the AM/FM radio bands. In addition, the bar antenna  30  may serve as an antenna for receiving an electric wave used for a car phone or may serve as an antenna for receiving both of the electric waves of the AM/FM radio bands and the electric wave used for the car phone. 
   The first and second planar antennas  40  and  50  are mounted on the main surface  20   a  of the antenna base  20  between the first and second ends  20   b  and  20   c  of the antenna base  20 . The first planar antenna  40  serves as an antenna for receiving an electric wave from a first satellite. The second planar antenna  50  serves as an antenna for receiving an electric wave from a second satellite. In the exemplary embodiment, the first planar antenna  40  serves as a GPS antenna receiving an electric wave from a GPS satellite as the first satellite. The second planar antenna  50  serves as an SDARS antenna receiving an electric wave from an SDARS satellite as the second satellite. 
   Specifically, the first planar antenna  40  includes a first circuit board  42  having a main surface  42   a  and a rear surface (not shown) opposed to each other, a first planar antenna element  44  mounted on the main surface  42   a  of the first circuit board  42 , and a first LNA circuit (not shown) mounted on the rear surface of the first circuit board  42 . The first planar antenna element  44  serves as an element for receiving an electric wave from the first satellite (GPS satellite). In the exemplary embodiment, the first antenna element  44  includes a patch antenna. The first LNA circuit is a circuit for amplifying a signal received by the first planar antenna element  44 . AS shown in  FIG. 1(B) , the first circuit board  42  is mounted on the first shield wall  22 . The first LNA circuit is shielded by the first shield wall  22 . 
   Similarly, the second planar antenna  50  includes a second circuit board  52  having a main surface  52   a  and a rear surface (not shown) opposed to each other, a second planar antenna element  54  mounted on the main surface  52   a  of the second circuit board  52 , and a second LNA circuit (not shown) mounted on the rear surface of the second circuit board  52 . The second planar antenna element  54  serves as an element for receiving an electric wave from the second satellite (SDARS satellite). In the exemplary embodiment, the second antenna element  54  includes a patch antenna. The second LNA circuit is a circuit for amplifying a signal received by the second planar antenna element  54 . As shown in  FIG. 1(B) , the second circuit board  52  is mounted on the second shield wall  23 . The second LNA circuit is shielded by the second shield wall  23 . 
   The top case  60  serves as a case for covering the bar antenna  30  and the first and second antennas  40  and  50  in cooperation with the antenna base  20 . The top case  60  includes a cylindrical bar antenna cover  62  covering the bar antenna  30  and a cup-shaped upper case  64  covering the first and second planar antennas  40  and  50 . The upper case  64  has four screw bosses  641  protruding downwardly from an inner wall  64   a  thereof at four portions. 
   Meanwhile, in the base portion  21  of the antenna base  20 , four holes  211  (only two holes are shown in  FIG. 1(B) ) are formed at positions corresponding to the four screw bosses  641 , respectively. The top case  60  is mounted on the antenna base  20  by fitting four screws (not shown) through the four holes  211  and the four screw bosses  641 . 
   Although not shown in  FIG. 1(B) , a hole is formed at the center, in which the first and second shield walls  22  and  23  of the antenna base  20  come in contact with each other, of the base portion  21  of the antenna base  20 . A bolt post  25  protruding downwardly from the base portion  21  is formed in the base portion  21  of the antenna base  21  at the position where the hole is formed. The hole and the bolt post  25  bind three output cables (not shown) drawn from the base portion of the bar antenna  30  and the first and second circuit boards  42  and  52 . 
   Although not shown in  FIG. 1 , the antenna base  20  is mounted on a base pad. 
   In the first exemplary embodiment of the invention, the complex antenna device  10  includes a metallic member  70  provided at the second end  20   c  of the antenna base  20 . The GPS antenna  40  is provided close to the bar antenna  30  and the SDARS antenna  50  is provided close to the metallic member  70 . 
   As known in this technical field, the GPS antenna  40  preferably receive an electric wave from the GPS satellite about once per 5 seconds. On the other hand, the SDARS antenna  50  is required to constantly receive an electric wave from the SDARS satellite. For this reason, the SDARS antenna  50  requires a better directivity than that of the GPS antenna  40 . 
   The metallic member  70  is provided at a specific position and has a size, so as to substantially remove physical influence of the bar antenna  30  on the second planar antenna (SDARS antenna)  50 . If the size of the metallic member  70  is so small, it can not remove the physical influence. Accordingly, a predetermined size is needed for removing the physical influence. In the exemplary embodiment, the metallic member  70  is formed of a metallic rod disposed upright at the specific position on the main surface  20 . In this manner, the metallic rod  70  is disposed upright at the opposite side to the bar antenna  30 , with the first and second antennas  40  and  50  interposed therebetween, thereby improving directivity of the second planar antenna (SDARS antenna)  50 . The metallic rod  70  may be preferably provided to extend up to adjacent to or higher than receiving plates of the first and second antennas  40  and  50  so as to remove physical influence of the bar antenna  30  further effectively. 
   In  FIGS. 2 and 3 , there are shown a directive property of the second planar antenna (SDARS antenna)  50  in the complex antenna device  10  (the improved product) according to the invention with the metallic rod  70  shown in  FIG. 1  and a directive property of the second planar antenna (SDARS antenna)  50  in the known complex antenna device (the known product) without the metallic rod  70 . 
     FIG. 2  is a diagram illustrating directivity of the second planar antenna (SDARS antenna)  50  in a case where a satellite wave from the SDARS satellite is received when the elevation angle of the SDARS satellite is in the range of 20° to 60°.  FIG. 2(A)  shows directivity when the elevation angle is 20°,  FIG. 2(B)  shows directivity when the elevation angle is 25°,  FIG. 2(C)  shows directivity when the elevation angle is 30°,  FIG. 2(D)  shows directivity when the elevation angle is 40°,  FIG. 2(E)  shows directivity when the elevation angle is 50°, and  FIG. 2(B)  shows directivity when the elevation angle is 60°. 
     FIG. 3  is a diagram illustrating directivity of the second planar antenna (SDARS antenna)  50  in a case where a satellite wave from the SDARS satellite is received when the elevation angle is 0°. 
   As known in this technical field, the more it is close to the perfect circle (i.e., the more roundness is high), the more a ripple of the directivity is small and good. It can be appreciated from  FIGS. 2 and 3  that the directivity of the improved product is closer to the perfect circle than that of the known product (i.e., roundness is high) and is more improved than that of the known product. 
   A complex antenna device  10 A according to a second exemplary embodiment of the invention will be described with reference to  FIG. 4 .  FIG. 4(A)  is a perspective view of a top case  60  of the complex antenna device  10 A, as obliquely viewed from the lower side.  FIG. 4(B)  is a perspective view of the complex antenna device  10 A with the top case  60  detached therefrom, as obliquely viewed from the upper side. 
   The complex antenna device  10 A has the same configuration as the complex antenna device  10  shown in  FIG. 1 , except that a configuration of the metallic member is different as described below. Accordingly, reference numeral  70 A is given to the metallic member. The same reference numerals are given to what have the same function shown in  FIG. 1 . In order to simplify description (in order to avoid duplication of description), the description about the same constituent elements will be omitted. 
   The metal member  70 A includes a metallic tape attached to a specific position in the inner wall  64   a  of the upper case  64  of the top case  60 . 
   The inventors confirmed that the directivity was improved in the complex antenna device  10 A with such a configuration as well as the complex antenna device  10  shown in  FIG. 1  in comparison with the known complex antenna device. 
   In the exemplary embodiments shown in  FIGS. 1 to 4 , although there are provided two planar antennas of the first planar antenna (GPS antenna)  40  and the second planar antenna (SDARS antenna)  50 , the complex antenna device according to the invention is applicable to a complex antenna device including only one planar antenna as the second planar antenna (SDARS antenna)  50 , exclusive of the first planar antenna (GPS antenna)  40 . 
   Next, a complex antenna device  10 B according to a third exemplary embodiment of the invention will be described with reference to  FIGS. 5 to 8 .  FIG. 5  is a perspective view of the complex antenna device  10 B as viewed from the upper side.  FIG. 6  is a perspective view of the complex antenna device  10 B as viewed from the lower side.  FIG. 7  is an exploded perspective view of the complex antenna device  10 B with the bar antenna cover  62  detached, as viewed from the upper side.  FIG. 8  is an exploded perspective view of the complex antenna device  10 B as viewed from the lower side. 
   The complex antenna device  10 B is largely different from the above-described complex antenna devices  10  and  10 A, in that the complex antenna device  10 B includes only one planar antenna device  50 A. Accordingly, the same reference numerals are given to what have the same function as the complex antenna device  10  shown in  FIG. 1 . Hereinafter, in order to simplify description, only parts different from the complex antenna device  10  will be described. 
   The complex antenna device  10 B includes an antenna base  20 A, a bar antenna (not shown), a planar antenna  50 A, a top case  60 A made of resin, and a base pad  80 . 
   The antenna base  20 A is made of die-casting materials such as zinc, aluminum, and magnesium. The antenna base  20 A has a main surface  20   a  and a first end  20   b  and a second end  20   c  opposed to each other. The antenna base  20 A has a substantially flat base portion  21 A. The antenna base  20 A has three screw bosses  26  protruding upwardly from the main surface  20   a  at the first end  20   b . A circuit board  15  is mounted on the three screw bosses  26 . The circuit board  15  has three holes  15   a  corresponding to the three screw bosses  26 . Three screws  17  are fitted into the three screw bosses  26  through the three holes  15   a , thereby fixing the circuit board  15  on the three screw bosses  26 . 
   A base portion of the bar antenna (not shown) is mounted on the circuit board  15 . The bar antenna is provided at the first end  20   b  of the antenna base  20 A. The bar antenna includes a metal (not shown). The bar antenna is provided so that a front end thereof is inclined in a direction departing from the planar antenna  50 A. In the exemplary embodiment, the bar antenna serves as an antenna for receiving electric waves of AM/FM radio bands. In addition, the bar antenna may serve as an antenna for receiving an electric wave used for a car phone or may serve as an antenna for receiving both of the electric waves of the AM/FM radio bands and the electric wave used for the car phone. 
   The planar antenna  50 A is mounted on the main surface  20   a  of the antenna base  20 A between the first and second ends  20   b  and  20   c  of the antenna base  20 A. The planar antenna  50 A is an SDARS antenna receiving an electric wave from an SDARS satellite. 
   The planar antenna  50 A includes a circuit board  52 A having a main surface  52   a  and a rear surface  52   b  opposed to each other, a planar antenna element  54  mounted on the main surface  52   a  of the circuit board  52 A, an LNA circuit (not shown) mounted on the rear surface  52   b  of the circuit board  52 A, and a shield case  58  shielding the LNA circuit. The planar antenna element  54  serves as an element for receiving an electric wave from an SDARS satellite. In the exemplary embodiment, the planar antenna element  54  includes a patch antenna element. The LNA circuit serves as a circuit for amplifying the signal received by the planar antenna element  54 . 
   The top case  60 A is a case for covering the bar antenna and the planar antenna  50 A in cooperation with the antenna base  20 A. The top case  60 A includes the cylindrical antenna cover  62  covering the bar antenna and a cup-shaped upper case  64 A covering the planar antenna  50 A and the circuit board  15 . The upper case  64 A has four screw bosses  641  protruding downwardly from the corresponding four portions from the inner wall  64   a.    
   In the base portion  21 A of the antenna base  20 A, four holes  211  are formed at the positions corresponding to the four screw bosses  641 . 
   The base bad  80  is made of elastic resin. The base pad  80  includes an installation portion  81  on which the antenna base  20 A is mounted, a ring-shaped wall portion  82  protruding upwardly in an outer periphery of the installation portion  81 , a skirt portion  83  protruding downwardly in the outer periphery of the installation portion  81 , a ring-shaped pad portion  84  protruding downwardly from the installation portion  81  in the vicinity of a circular opening  81   a  formed at the center of the installation portion  81 . In the installation portion  81  of the base pad  80 , four holes  811  are formed at the positions corresponding to the four holes  211  of the antenna base  20 A, respectively. 
   The four screws  91  are fitted through the four holes  811  of the installation portion  81  of the base pad  80 , the four holes  211  of the base portion  21 A of the antenna base  20 A, and the four screw bosses  641  of the upper case  64 A of the top case  60 A. Accordingly, the top case  60 A is mounted on the antenna base  20 A. 
   In a state where the ring-shaped wall portion  82  of the base pad  80  is fitted to an outer peripheral portion  212 , the base pad  80  is mounted on the antenna base  20 A. The skirt portion  83  and the ring-shaped pad portion  84  of the base pad  80  come in close contact with a vehicle body to seal a space between the vehicle body and the base pad  80 . That is, the skirt portion  83  of the base pad  80  has a waterproof function and does not damage the exterior of the vehicle body. The ring-shaped pad  84  has a waterproof function. 
   A hole  21  is formed in the center of the base portion  21 A of the antenna base  20 A. In the center in which the hole  21   a  is formed, a cylindrical bolt post portion  25  protruding downwardly from the base portion  21 A is formed in the base portion  21 A of the antenna base  20 A. The hole  21   a  and the bolt post portion  25  bind output cables (not shown) drawn from the circuit boards  15  and  52 . 
   In the third exemplary embodiment of the invention, the complex antenna device  10 B includes a metallic member  70 B provided at the second end  20   c  of the antenna base  20 A. 
   Specifically, the upper case  64 A of the top case  60 A has one screw boss  642  protruding downwardly from the inner wall  64   a  thereof at specific position. Meanwhile, the base portion  21 A of the antenna base  20 A has a screw boss  72  at the position (at the specific position) corresponding to the one screw boss  642  so as to mount the antenna base  20 A on the top case  60 A. In the installation portion of the base pad  80 , one hole  812  is formed at the position corresponding to the screw boss  72  of the antenna base  20 A. 
   The one metallic screws  74  is fitted through the one hole  812  of the installation portion  81  of the base pad  80 , the screw boss  72  of the base portion  21 A of the antenna base  20 A, and the one screw boss  642  of the upper case  64 A of the top case  60 A. Accordingly, the top case  60 A is also mounted on the antenna base  20 A. 
   That is, the metallic member  70 B includes the screw boss  72  of the antenna base  20 A and the metallic screw  74  penetrating the screw boss  72 . 
   As described above, the metallic member  70 B is disposed upright at the side opposite to the bar antenna, thereby improving the directivity of the planar antenna (SDARS antenna)  50 A. 
   While the exemplary embodiments of the invention have been described above, the invention is not limited to the above-described exemplary embodiments. In the third exemplary embodiment of the invention, the metallic member  70 B includes the combination of the screw boss  72  and the metallic screw  74 . However, when the screw  74  is made of resin, for example, the metallic member  70 B may include only the screw boss  72 . 
   The entire disclosure of Japanese Patent Application No 2006-238792, filed on Sep. 4, 2006 is expressly incorporated by reference herein. 
   While this invention has been described in conjunction with the specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, exemplary embodiments of the invention as set forth herein are intended to be illustrative, not limiting. There are changes that may be made without departing from the sprit and scope of the invention.