Patent Publication Number: US-8525746-B2

Title: In-vehicle antenna system and method

Description:
FIELD 
     The present disclosure relates to a system and method of communicating radio frequency (RF) signals between antennas, and more particularly to a system and method of communicating RF signals between an exterior environment and an interior cabin. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     Certain vehicle regulations recently enacted require passenger vehicles to use solar management glass coatings. This type of glass coating causes less infrared energy to be transmitted into the interior cabin of the vehicle, which in turn reduces the heat load in the interior cabin of the vehicle. However, this coating does not generally allow for radio frequency (RF) signals to pass through the glass. As a result, if a portable electronic device is being used within the interior cabin of the vehicle, RF signals such as cellular telephone signals or global positioning system (GPS) signals will generally be unavailable. The portable electronic device is unable to receive the RF signals needed to perform some types of functions. For example, if a personal navigation device (PND) is placed within the interior cabin of the vehicle, a weak or non-existent GPS signal is available. As a result, the PND may not be able to provide positioning data. Moreover, if there is a weak or non-existent signal within the interior cabin, portable electronic devices will constantly search for an RF signal. Searching for RF signals will reduce the battery life of a portable electronic device, which can lead to customer dissatisfaction and complaints. Accordingly, there is a need in the art for a system that will allow RF signals to enter the interior cabin of a vehicle that utilizes solar management glass coatings. 
     SUMMARY 
     The present invention provides a method and system for communicating radio frequency (RF) signals between antennas. An antenna system connectable to a vehicle includes an exterior antenna, an interior antenna, and a data transmission line. The vehicle has a wall including an outer surface and an inner surface that generally opposes the outer surface, where the inner surface and the outer surface cooperate together to create an aperture. The wall defines an exterior environment and an interior cabin. The exterior antenna is located within the exterior environment and is connectable to the vehicle. The exterior antenna transmits and receives RF signals to and from an external RF device that is located in the exterior environment. The interior antenna is located within the interior cabin defined by the inner surface of the wall, where the interior antenna receives and transmits RF signals to and from an interior RF device located within the interior cabin. The data transmission line transmits RF signals. The data transmission line is in communication with both the exterior antenna and the interior antenna, where the transmission line passes through the aperture located in the plate between the exterior antenna and the interior antenna. The interior antenna communicates RF signals obtained from the interior RF device located within the interior cabin through the transmission line to the exterior antenna, and the exterior antenna communicates RF signals obtained from the external RF device through the transmission line to the interior antenna. 
     In an embodiment of the present invention, the interior antenna is located on a vehicle overhead console, a vehicle center console, an instrument panel, an A pillar, a B pillar, a C pillar, a D pillar, an integrated center stack faceplate, a front windshield, a rear windshield, a sunroof, or interior seats. 
     In another embodiment of the present invention, the exterior antenna is located on one of a roof of the vehicle, a cowl base, a side rearview mirror, a head lamp, a tail lamp, Center High Mounted Stop Lamps (CHMSL), a front windshield, a rear windshield, a sunroof, or a deck lid antenna. 
     In yet another embodiment of the present invention, the exterior antenna is a patch antenna having a ground plane. 
     In an embodiment of the present invention, the exterior antenna is attached to an exterior vehicle antenna, wherein the exterior vehicle antenna is used to transmit RF signals to a vehicle transceiver. 
     In another embodiment of the present invention, the interior antenna is a patch antenna. 
     In yet another embodiment of the present invention, the interior antenna provides a generally hemispherical RF pattern within the interior cabin. 
     In an embodiment of the present invention, the interior antenna is sized to receive and transmit either global positioning signals (GPS), satellite digital audio radio service (SDARS), or cellular signals. 
     In another embodiment of the present invention, at least one of the exterior antenna and the interior antenna are passive antennas. 
     In an embodiment of the present invention, the data transmission line is a coaxial cable. 
     A method of sending and receiving radio frequency (RF) signals from a vehicle is also disclosed. The vehicle has a wall including an outer surface and an inner surface that generally opposes the outer surface. The inner surface and the outer surface cooperate together to create an aperture. The method comprises the step of transmitting a first RF signal from an external RF device to an exterior antenna. The exterior antenna is disposed on the outer surface of the wall. The method further comprises the step of communicating the first RF signal from the exterior antenna to an interior antenna located within an interior cabin through a data transmission line. The wall defines an exterior environment and the interior cabin, where the data transmission line is in communication with both the exterior antenna and the interior antenna and passes through the aperture in the wall. The method further comprises the step of radiating the first RF signal from the interior antenna to the interior cabin such that an interior RF device receives the first RF signal. The method further comprises the step of transmitting a second RF signal from the interior RF device to the interior antenna. Finally, the method comprises the step of communicating the second RF signal from the interior antenna to the exterior antenna through the transmission line. 
     In an embodiment of the present invention, the method further comprises the step of transmitting the second RF signal from the exterior antenna to the external RF device. 
     In another embodiment of the present invention, the method further comprises the step of locating the interior antenna on either a vehicle overhead console, a vehicle center console, an instrument panel, an A pillar, a B pillar, a C pillar, a D pillar, an integrated center stack faceplate, a front windshield, a rear windshield, a sunroof, or interior seats. 
     In yet another embodiment of the present invention, the method further comprises the step of locating the exterior antenna on either a roof of the vehicle, a cowl base, a side rearview mirror, a head lamp, a tail lamp, a Center High Mounted Stop Lamps (CHMSL), a front windshield, a rear windshield, a sunroof, or a deck lid antenna. 
     In an embodiment of the present invention, the method further comprises the step of establishing the exterior antenna as a patch antenna having a ground plane. 
     In another embodiment of the present invention, the method further comprises the step of attaching the exterior antenna to an exterior vehicle antenna, wherein the exterior vehicle antenna is used to transmit RF signals to a vehicle transceiver. 
     In yet another embodiment of the present invention, the method further comprises the step of establishing the interior antenna as a patch antenna. 
     In an embodiment of the present invention, the method further comprises the step of providing a generally hemispherical RF pattern within the interior cabin by the interior antenna. 
     In another embodiment of the present invention, the method further comprises the step of sizing the interior antenna to receive and transmit either global positioning signals (GPS), satellite digital audio radio service (SDARS), or cellular signals. 
     In yet another embodiment of the present invention, the method further comprises the step of establishing at least one of the exterior antenna and the interior antenna as passive antennas. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a schematic illustration of an exemplary antenna assembly including two antennas on a vehicle; 
         FIG. 2  illustrates an exterior view of the vehicle shown in  FIG. 1 ; 
         FIG. 3A  is illustrates a portion of an interior of the vehicle shown in  FIG. 1 ; and 
         FIG. 3B  illustrates a portion of the interior of the vehicle shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     With reference to  FIG. 1 , a schematic view of a vehicle is generally indicated by reference number  10 , where an antenna system  20  for receiving radio frequency (RF) signals is connected to the vehicle  10 . The antenna system  20  includes an exterior antenna  22  and an interior antenna  24  that each transmit and receive RF signals as well as a data transmission line  26  used to communicate RF signals between the exterior antenna  22  and the interior antenna  24 . The vehicle  10  includes a wall  30  having an outer surface  32  and an inner surface  34  generally opposing the outer surface  32 . The outer surface  32  and the inner surface  34  cooperate together to create an aperture  36  located within the wall  30 . The wall  30  is constructed from a material that does not generally allow for RF signals to pass through. In one embodiment, the wall  30  is the roof of the vehicle  10  and is constructed from a metallic material such as, for example, a steel alloy. Alternatively, the wall  30  can be a glass pane, such as the rear glass of the vehicle  10 . The glass pane is coated with a solar management glass coating that does not generally allow for RF signals to pass through. 
     The wall  30  defines an exterior environment  44  and an interior cabin  46  of the vehicle  10 . The exterior environment  44  includes the environment that is located outside of the vehicle  10 , while the interior cabin  46  includes the environment within the vehicle  10 . The exterior environment  44  is typically any type of outdoor environment. The interior cabin  46  includes an area between a headliner  48  and the wall  30  as well as the interior of the vehicle  10 . The exterior antenna  22  is located in the exterior environment  44  and the interior antenna element  24  is located within the interior cabin  46 . Although  FIGS. 1-3B  illustrate the antenna system  20  employed in a vehicle, those skilled in the art will appreciate that the antenna system  20  can be used in any application where RF signals are transmitted or received. 
     The aperture  36  is located and sized within the wall  30  such that the transmission line  26  can pass through the aperture  36 . The aperture  36  allows for the transmission line  26  to be located within both the exterior environment  44  and the interior cabin  46 . In the embodiment as shown, a first end  28  of the transmission line  26  is in electrical communication with the interior antenna  24  and a second end  29  of the transmission line  26  is in electrical communication with the exterior antenna  22 , thereby connecting the exterior antenna  24  located in the exterior environment  44  with the interior antenna  24  located in the interior cabin  46 . The transmission line  26  is any type of transmission line that carries RF signals such as, for example, a coaxial cable. In one embodiment, each of the ends  28  and  29  of the transmission line  26  are connected to the exterior and interior antennas  22  and  24  by a coaxial feed (not shown). 
     The interior cabin  46  of the vehicle  10  typically has poor or non-existent RF signal reception. This is because the vehicle  10  has a roof constructed of a metallic material and the vehicle glass is typically coated with a solar management glass coating. Both the roof and the coated vehicle glass do not generally allow for RF signals to pass through. Turning to  FIG. 2 , an illustration of the exterior of the vehicle  10  is shown. The vehicle  10  has a roof  50  constructed of a metallic material such as, for example, a steel alloy. The vehicle  10  also includes a front windshield  52 , a rear windshield  54 , a sunroof  56 , and side windows  58  that are coated with a solar management glass coating that substantially interferes with the transmission of RF signals. As a result, the antenna system  20  is employed to communicate RF signals between the interior cabin  46  and the exterior environment  44  ( FIG. 1 ). 
     The exterior antenna  22  can be located along any exterior surface of the vehicle  10  that is capable of mounting the exterior antenna  22  thereon. In the illustration as shown, the exterior antenna  22  is mounted on the roof  50  of the vehicle  10 . However, in another embodiment, the exterior antenna  22  could be mounted to a cowl base  60 , a side rearview mirror  62 , a head lamp  64 , a tail lamp  66 , Center High Mounted Stop Lamps (CHMSL)  68 , the front windshield  52 , the rear windshield  54 , the sunroof  56 , or a deck lid  70 . Turning back to  FIG. 1 , the interior antenna  24  can be positioned in any location within the interior cabin  46  that allows for the interior antenna  24  to receive and transmit RF signals located within the interior cabin  46 .  FIG. 1  illustrates the interior antenna  24  positioned within an overhead console  74  of the vehicle  10 , however, it is understood that the interior antenna  24  can be positioned in other locations as well. For example, turning to  FIGS. 3A-3B , the interior antenna  24  could be positioned in a vehicle center console  76 , an instrument panel  78 , an A, B, C or D pillar  80 , an integrated center stack faceplate  82 , the front windshield  52  ( FIG. 2 ), the rear windshield  54  ( FIG. 2 ), the sunroof  56 , or the interior seats  84 . Thus, while the embodiment in  FIG. 1  illustrates the exterior antenna  22  as a roof mounted antenna and the interior antenna  24  located in the overhead console  74 , other packaging options for the exterior and interior antennas  22  and  24  exist as well. This means that the antenna system  20  can be packaged such that the exterior antenna  22  can be positioned at various locations along the exterior surface of the vehicle  10 . At the same time, the interior antenna  24  can be positioned in various locations within the interior cabin  46  as well. As a result, the exterior and interior antennas  22  and  24  can be positioned in various locations either in or on the vehicle in an effort to accommodate the unique packaging restraints of a specific vehicle. The locations of the exterior and interior antennas  22  and  24  can also be positioned to accommodate the cable attenuation of the transmission line  26 . Specifically, the packaging locations of the interior and exterior antenna  22  and  24  may depend on the available length of the transmission line  26 , as a longer data transmission line  26  results in greater signal attenuation. 
     In the embodiment as shown, the antenna system  20  has a passive design. This means that the exterior and interior antennas  22  and  24  each do not include an amplifier. However, those skilled in the art will appreciate that the antenna system  20  can also include an active design as well, which means the exterior and interior antennas  22  and  24  are amplified. Specifically, the antennas  22 ,  24  could have an active design using a two-way amplifier. However, it may be more cost effective to employ a passive design instead in some embodiments, as a passive design does not need an amplifier, therefore reducing cost as well as complexity of the antenna system  20 . Moreover, a passive design does not require vehicle electrical load and would not typically impact electric consumption or power requirements of the vehicle  10 . 
     In the embodiment as shown in  FIG. 1 , the exterior antenna  22  is a patch type antenna having a ground plane. Although  FIG. 1  illustrates the exterior antenna  22  as a patch type antenna those skilled in the art will appreciate that other types of antennas may be used as well. For example, in another embodiment the exterior antenna  22  could be a mirror type antenna. The exterior antenna  22  can also be attached to or integrated with a vehicle antenna  90 . The vehicle antenna  90  can be any type of externally mounted antenna used to transmit RF signals to the vehicle&#39;s  10  transceiver  92 .  FIG. 1  illustrates the vehicle antenna  90  as a fin type antenna, however it is understood that other types of antennas may also be employed. Various other types of antennas (not illustrated) used to transmit and receive different types of RF signals can be located within the vehicle antenna  90 . For example, the vehicle antenna  90  could include a satellite digital audio radio service (SDARS) antenna or a cellular antenna in addition to the exterior antenna  90 . The other antennas located within the vehicle antenna  90  are connected to the respective vehicle transceiver  92  through a data line  94 . The data line  94  is any type of transmission line for carrying radio frequency signals such as, for example, a coaxial cable.  FIG. 1  illustrates two separate vehicle transceivers  92 , namely a cellular transceiver as well as a SDARS transceiver. 
       FIG. 1  illustrates the interior antenna  24  as a patch type antenna, however those skilled in the art will appreciate that other types of antennas may be used as well. The patch type antenna can be sized for a particular frequency. For example, if it is desired to pass (SDARS) signals, the patch type antenna can be sized to transmit and receive SDARS signals. Alternatively, in another example the patch type antenna could also be sized to transmit and receive cellular telephone signals. In one example, the interior antenna  24  can be several different patch antennas that are integrated to receive several different types of signals, such as, for example, a patch antenna that receives both SDARS as well as GPS signals. 
     The transmission line  26  communicates RF signals between the exterior antenna  22  and the interior antenna  24 . Specifically, the interior antenna  24  communicates RF signals obtained from the interior cabin  46  through the transmission line  26  to the exterior antenna  22 . The exterior antenna  22  communicates RF signals obtained from the external environment  44  through the transmission line  26  to the interior antenna  24 . If a portable electronic RF device (not shown) is located within the interior cabin  46  of the vehicle  10 , the electronic RF device is generally unable to send or receive RF signals from an external RF device that is located in the exterior environment  44 . This is because RF signal reception is typically poor or non-existent within the interior cabin  46  of the vehicle, as the roof  50 , the front windshield  52 , the rear windshield  54 , and the sunroof  56  ( FIG. 2 ) are constructed from materials that do not generally allow for RF signals to pass through. The portable electronic RF device can be any type of portable electronic device that is capable of transmitting RF signals, receiving RF signals, or both. For example, the electronic RF device could be a cellular telephone, a laptop computer with a wireless Internet connection, an AM/FM radio, or a personal navigation device (PND). The external RF device is any type of structure located in the environment outside of the interior cabin  46  of the vehicle  10  that is capable transmitting RF signals, receiving RF signals or both. For example, the external RF device could be a GPS satellite, a cellular telephone tower, an AM radio tower, or an FM radio tower. 
     In one example, if a portable electronic RF device such as a PND is located within the interior cabin  46  of the vehicle, the RF signals can not generally travel through the wall  30  and communicate with an external RF device such as a GPS satellite. Instead, the antenna system  20  transmits the RF signals from the interior cabin  46  to the satellite located outside of the vehicle  10 . First, the portable electronic RF device communicates an RF signal to the interior antenna  24 . The RF signal is communicated from the interior antenna  24 , through the transmission line  26 , and to the exterior antenna  22 . The exterior antenna  22  communicates the RF signal to a satellite, where the RF signal contains information such as, for example, the position of the vehicle  10  in relation to Earth. The satellite then communicates an RF signal to the exterior antenna  22  containing information such as, for example, directions from the vehicle&#39;s present position to another predetermined destination. The RF signal is communicated from the exterior antenna  22 , through the transmission line  25 , and to the interior antenna  24 . The interior antenna  24  then radiates the RF signal into the interior cabin  46 , and provides an RF signal to the portable electronic RF device. In the embodiment as illustrated, the interior antenna  24  provides a generally hemispherical pattern  96  within the interior cabin  46 , however it is understood that the interior antenna  24  can radiate different types of antenna patterns as well. 
       FIG. 1  illustrates a fastening device  98  that is used to position the exterior antenna  22  on the outer surface  32  of the wall  30  and the interior antenna  24  within the interior cabin  46 . The fastening device  98  can be any type of fastener that is used to secure the exterior antennas  22  to the wall  30  such as, for example, a bolt. The antenna assembly  20  can be installed on the vehicle  10  during production. Alternatively, the antenna assembly  20  is a retrofit, where the aperture  36  could be added to the vehicle  10  and the exterior and interior antennas  22  and  24  as well as the transmission line  26  could be installed after production. 
     With continued reference to  FIGS. 1-3B , a method for communicating an RF signal with the antenna system  20  is discussed. The method begins at a first step where the antenna system  20  including the exterior antenna  22  and the interior antenna  24  is established. The outer surface  32  and the inner surface  34  of the wall  30  cooperate together to create the aperture  36 . The aperture  36  is located within and sized in the wall  30  such that the transmission line  26  can pass through the aperture  36 , thereby connecting the exterior antenna  22  located in the exterior environment  44  with the interior antenna  24  located in the interior cabin  46 . In one embodiment, the antenna system  20  is connected to a vehicle  10 , however it is understood that the antenna system  20  may be employed in other applications as well. The method then proceeds to a second step. 
     In the second step, a first RF signal is transmitted from an external RF device to the exterior antenna  22 . The first RF signal can be any type of radio frequency signal such as, for example, a cellular telephone signal. The external RF structure is any type of structure that is capable of transmitting RF signals, receiving RF signals, or both. For example, the external RF structure could be a GPS satellite, a cellular telephone tower, and an FM or AM radio tower. The method may then proceed to a third step. 
     In the third step, the first RF signal is communicated from the exterior antenna  22  to the interior antenna  24  through the transmission line  26 . The transmission line  26  communicates RF signals between the exterior antenna  22  and the interior antenna  24 . Specifically, the exterior antenna  22  communicates RF signals obtained from the external environment  44  through the transmission line  26 , and to the interior antenna  24 . The method may then proceed to a fourth step. 
     In the fourth step, the first RF signal is radiated from the interior antenna  24  and into the interior cabin  46  such that the electronic RF device receives the first RF signal. For example,  FIG. 1  illustrates the interior antenna  24  provides a generally hemispherical pattern  96  within the interior cabin  46 . However, it is understood that the interior antenna  24  can radiate different types of antenna patterns as well. The method may then proceed to a fifth step. 
     In the fifth step, a second RF signal from the electronic RF device is transmitted to the interior antenna  24 . The electronic RF device any type of portable electronic device that is capable of transmitting RF signals, receiving RF signals, or both. In the fifth step, the electronic RF device transmits the second RF signal into the interior cabin  46  of the vehicle  10 , and the interior antenna  24  receives the second RF signal. The method may then proceed to a sixth step. 
     In the sixth step, the second RF signal is communicated from the interior antenna  24  to the exterior antenna  22  through the transmission line  26 . Similar to the third step, the interior antenna  24  communicates RF signals obtained from the interior cabin  46  through the transmission line  26  to the exterior antenna  22 . The method may then proceed to a seventh step. 
     In the seventh step, the second RF signal is transmitted from the exterior antenna  22  to the external RF device. For example, if the RF signal is a GPS signal, then the second RF signal is communicated to a GPS satellite. The second RF signal can include information, such as for example, the position of the vehicle  10  in relation to the Earth. In one embodiment, the method may then proceed back to the second step. For example, the GPS satellite could then communicate a RF signal to the exterior antenna  22  containing information such as, for example, directions from the vehicle&#39;s present position to another predetermined destination. Alternatively, the method may then terminate. 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.