Abstract:
A headphone antenna assembly capable of efficiently receiving both satellite and terrestrial radio frequency signals in the Satellite Digital Audio Radio Service (SDARS) frequency band. Two embodiments are presented, one utilizing a patch antenna and the other utilizing a quadrifilar antenna.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     (not applicable)  
       BACKGROUND OF INVENTION  
       [0002]     SDARS is a satellite broadcast service recently approved by the U.S. Federal Communications Commission (FCC) which provides satellite and terrestrial transmission of digital audio programs to compatible radio receivers. The SDARS frequency band is 2320 to 2345 MHz. The radio receivers can be stationary or mobile and are configured to receive signals from satellites as well as terrestrial repeaters.  
         [0003]     Currently, most SDARS automotive antenna modules comprise patch antennas placed on vehicle roofs. As SDARS services are becoming more popular, there is a need of wearable SDARS devices. In this case, the receivers can be placed on the wearer&#39;s body in a similar fashion to MP3 players. Since wearable SDARS devices receive live signals, antenna placement is very critical. The best location for the antenna is on top of the wearer&#39;s head. This guarantees acceptable reception in all directions. Since headphones are also used in wearable SDARS receivers, it will be very beneficial if the antenna is part of the headphones or it is placed on top of the headphones.  
         [0004]     One embodiment of the novel assembly is shown in  FIG. 1 . The patch antenna module is housed inside and on top of the headband. This antenna is capable of efficiently receiving both satellite and terrestrial signals in all directions.  FIG. 2  shows the details of the cable assembly of the novel structure such as the headphone wires and audio connector and the antenna radio frequency cable and connector.  FIG. 3  shows the details of the patch antenna module.  FIG. 4  shows the wearable receiver and headphone antenna assembly.  FIG. 5  shows an alternative embodiment where a short quadrifilar antenna is used.  
       SUMMARY OF INVENTION  
       [0005]     In a first aspect of the present invention, the headphone antenna assembly includes a patch antenna module placed inside the headband. The audio and radio frequency wires are bundled or molded together forming a single structure of three cables.  
         [0006]     In a second aspect of the present invention, the patch antenna of the first embodiment is replaced by a short quadrifilar antenna.  
         [0007]     In a third aspect of the present invention, the metallic rings are shaped into tubular form and inserted inside the tubular quadrifilar antenna. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0008]      FIG. 1  is a diagram showing the headphone antenna assembly of the first embodiment.  
         [0009]      FIG. 2  shows the details of the cable assembly of the novel structure.  
         [0010]      FIG. 3  shows the elements of the patch antenna module.  
         [0011]      FIG. 4  shows the wearable receiver and headphone antenna assembly.  
         [0012]      FIG. 5  shows an alternative embodiment of the assembly. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Illustrative embodiments and exemplary applications will now be described with reference to the accompanying drawings to disclose the advantageous teachings of the present invention.  
         [0014]     While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility.  
         [0015]      FIG. 1  shows the headphone antenna assembly  10 . The headband  11  interconnects earpieces  12  and  13 . The antenna module  14  is housed inside the top section  15  of headband  11 . The top section of the antenna module radio frequency (RF) cable  16  is connected to antenna module  14  and it is housed inside headband  11 . Audio cables  17  and  18  are connected to earpieces  12  and  13 , respectively. Cable sub-assembly  20  comprises of audio cable  18  and part of the RF cable  16 . Audio cables  17  and  18  and RF cable  16  are grouped together at point  19  and then forming cable assembly  21 . In sub-assembly  26 , the plastic jackets of audio cables  17 ,  18 , and RF cable  16  are molded or joined together. The bottom ends of audio cables  17  and  18  are molded together forming audio cable assembly  24  and connected to audio connector  22  while the bottom end of RF cable  16  is connected to RF connector  23 .  
         [0016]      FIG. 2  shows the details of cable assembly  21  of the novel structure. Audio cables  17 ,  18  and RF cable  16  are grouped together at point  19 . The plastic jackets of audio cables  17 ,  18 , and RF cable  16  are molded or joined together forming sub-assembly  26 . The length of sub-assembly  26  is approximately three feet. At the end of sub-assembly  26 , the cables are split into two sub-assemblies: RF cable  16  and audio cable assembly  24 . RF cable  16  is connected to RF connector  23 , while audio cables  17  and  18  are connected to audio connector  22 .  
         [0017]      FIG. 3  shows the elements of the patch antenna module  30 . Dielectric patch  31  is placed on top of the low noise amplifier (LNA) printed circuit board (PCB)  32  and it is connected to the LNA input. The LNA components are placed on the bottom side of PCB  32 . A shield cover  33  is placed on top of the LNA parts. A typical size of the dielectric patch  31  is: (x, y, z)=(18 mm, 18 mm, 4 mm). RF cable  16  is connected to the LNA output. A typical size of the antenna module including the patch antenna, PCB, and LNA cover, is: (x, y, z)=(22 mm, 22 mm, 8 mm). This small structure can easily be housed inside the top section of the headband. The diameter of RF cable  16  is approximately 1.7 mm.  
         [0018]      FIG. 4  shows the SDARS wearable receiver system  40  where the novel headphone antenna assembly  10  is connected to receiver  46 . The audio connector at the end of audio cable assembly  24  is connected to the receiver&#39;s audio connector  45 . The RF connector at the end of RF cable  16  is connected the receiver&#39;s RF connector  44 .  
         [0019]      FIG. 5  shows an alternative embodiment of the novel headphone antenna assembly in accordance with the teachings of the present invention. Here, quadrifilar antenna  51  and LNA  52  are attached to the headband. The input of quadrifilar antenna  51  is connected to the input of LNA  52 . RF cable  16  is connected to the output of LNA  52 . The rest of the assembly is substantially identical to assembly  10  of  FIG. 1 .