Abstract:
Antennas are integrated into shield cans by etching one or more slots from a body portion thereof. Multiple antennas can be grouped onto a single shield can to provide both cost and space saving features. Antenna feed and ground connections are positioned on the circuit board and connections to the antenna are made when the shield can connects to the circuit board assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims benefit of priority to U.S. Provisional Ser. No. 61/510,010, filed Jul. 20, 2011, and titled “ANTENNAS INTEGRATED IN SHIELD CAN ASSEMBLY”; the contents of which are hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates generally to the field of wireless communications; and more particularly, to antennas for such wireless communications being integrated into shield can assemblies, and related methods. 
         [0004]    2. Description of the Related Art 
         [0005]    Electromagnetic shielding in the form of shield cans is used extensively in communication circuits to isolate RF and digital circuits. Electromagnetic shielding, in effect, is used to keep intended signals internal to a region, or used to keep external signals from entering a region. Electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as RF shielding. The shielding can reduce the coupling of RF currents, radio waves, electromagnetic fields, and electrostatic fields between circuits in a communication system, with these circuits often located in close proximity to each other or on a shared circuit board. 
         [0006]    Because portability is an ongoing necessity in the portable electronics market, size constraints must remain a primary focus of component manufactures. Cell phones, for example, are becoming smaller in size and lighter in weight while providing an increased number of useable features, such as internet, radio, television (DVB-H), communications, and others. To meet the demand for multi-application cell phones, additional and/or larger antennas and other components have been required. Cell phone and other portable electronic device manufacturers are moving towards reducing size of components and eliminating unnecessary bulk space or reusing space. 
         [0007]    Antennas in wireless mobile devices are typically placed internal to the mobile device for aesthetics, cost, and other reasons. The antenna will require a certain volume to operate efficiently at a set frequency. With more features being designed into mobile devices such as FM radios, digital TV receivers, and GPS receivers, volume and circuit board area are becoming constrained. 
       SUMMARY OF THE INVENTION 
       [0008]    In a general embodiment of the invention, a shield can assembly comprises one or more antennas built into a volume thereof. The one or more antennas can be connected to a feed contact pad on a circuit board at a position adjacent to an edge of the shield can. 
         [0009]    In accordance with certain embodiments, a shield can is provided having one or more slots etched into a body thereof. At least one of the slots is adapted to radiate when excited, such as by electrical feed, or electromagnetic coupling of a nearby driven element, such that the shield can having an integrated antenna is adapted for at least one of transmission (Tx), or reception (Rx), of an electromagnetic signal. 
         [0010]    The shield can generally comprises a conductive body having one or more slots etched into at least a portion thereof. The slots can be disposed on one or more surfaces of the body including the top, bottom, or one of the side surfaces. 
         [0011]    In certain embodiments, a shield can having multiple embedded antennas comprises a first antenna defined by a first slot portion and a second antenna defined by a second slot portion. Each of the first and second slot portions can be disposed about one or more surfaces of the body portion of the shield can. The first antenna can be electrically driven via contact pads, or a transmission line. The second antenna can be electrically driven independent of the first antenna, or electromagnetically coupled to the first antenna. In this regard, multiple antennas can be provided within a single shield can body. 
         [0012]    In certain other embodiments, an antenna is provided comprising a shield can body having one or more slots embedded therein, a conductive enclosure adapted to substantially surround the shield can body having one or more slots embedded therein, and a transmission line connected to the shield can. The shield can is adapted to receive radiofrequency (RF) signals from the transmission line. In this regard, one or more slots of the conductive enclosure are excited by the shield can, and the shield can operates as a “feed source” or RF feed for one or more slots of the conductive enclosure. 
         [0013]    In other embodiments, a shield can body comprises two or more slots etched therein. One or more of the slots are electrically connected to a transmission line to form one or more electrically driven slots, and other slots therein are configured to electromagnetically couple with the one or more electrically driven slots. In this regard a first slot is electrically driven via a transmission line and a second of the slots is electromagnetically coupled to the first slot. 
     
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         [0014]      FIG. 1   a  illustrates a communications circuit for use with a wireless device in accordance with a prior art embodiment, wherein a shield can is used to isolate RF signals between an antenna radiator and an electric circuit. 
           [0015]      FIG. 1   b  illustrates the assembled circuit of  FIG. 1   a.    
           [0016]      FIG. 2   a  illustrates a communications circuit for use with a wireless device in accordance with a prior art embodiment, wherein a shield can is used to isolate RF signals between two antenna radiators and an electric circuit. 
           [0017]      FIG. 2   b  illustrates the assembled circuit of  FIG. 2   a.    
           [0018]      FIG. 3   a  illustrates a shield can comprising an antenna disposed on a surface thereof; the antenna being placed on the shield can provides reduced volume when compared to prior art embodiments of  FIG. 1(   a - b ). 
           [0019]      FIG. 3   b  illustrates the assembled circuit of  FIG. 3   a.    
           [0020]      FIG. 4   a  illustrates a shield can comprising two antennas each being disposed on a surface thereof; the antennas being placed on the shield can provides reduced volume when compared to prior art embodiments of  FIG. 2(   a - b ). 
           [0021]      FIG. 4   b  illustrates the assembled circuit of  FIG. 4   a.    
           [0022]      FIG. 5   a  illustrates a two-antenna module in accordance with the prior art embodiment of  FIG. 2   a.    
           [0023]      FIG. 5   b  illustrates an amount of space that can be reduced when providing a two-antenna module with the antennas built into a shield can. 
           [0024]      FIG. 6   a  illustrates a shield can comprising a pair of slots etched from a body portion of the shield can, the slots are adapted to radiate RF signals driven from feed contact pads on a circuit board. 
           [0025]      FIG. 6   b  illustrates the assembled circuit of  FIG. 6   a.    
           [0026]      FIG. 7  illustrates a conductive structure comprising slots etched therein for radiating RF signals, the slots are driven by adjacent feed contacts. 
           [0027]      FIG. 8   a  illustrates a shield can having two antennas disposed on a surface thereof, and a conductive structure adapted to substantially surround the shield can, the conductive structure comprises two slots, wherein each of the slots of the conductive structure is adapted to electromagnetically couple with the antennas of the shield can. 
           [0028]      FIG. 8   b  illustrates the assembled circuit of  FIG. 8   a.    
           [0029]      FIG. 9   a  illustrates an embodiment wherein a conductive structure comprises a slot etched into top surface thereof. 
           [0030]      FIG. 9   b  illustrates an embodiment wherein a conductive structure comprises two slots etched into a top surface thereof. 
           [0031]      FIG. 9   c  illustrates an embodiment wherein a conductive structure comprises three slots etched into a top surface thereof. 
           [0032]      FIG. 9   d  illustrates an embodiment wherein a conductive structure comprises a slot etched into a side surface thereof. 
           [0033]      FIG. 10   a  illustrates an embodiment wherein a circuit board comprises a shield can having two antennas therein, and a conductive structure assembled to sat least partially surround the shield can; the conductive structure comprises two slots, wherein each of the slots is adapted to couple with one of the respective antennas of the shield can. 
           [0034]      FIG. 10   b  illustrates the assembled circuit of  FIG. 10   a.    
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    In the following description, for purposes of explanation and not limitation, details and descriptions are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments that depart from these details and descriptions. 
         [0036]    In a general embodiment, one or more antennas can be configured within a shield can structure. The shield can comprises a conductive structure having a top surface and one or more side walls extending perpendicular therefrom. The shield can is positioned over at least a portion of a radio circuit of a circuit board, and at least one antenna feed contact is couple to a slot of the shield can for communicating RF currents. 
         [0037]    In another embodiment, a second conductive structure is configured to at least partially surround the first conductive structure. In this regard, the second conductive structure may comprise one or more slots therein. The slots of the second conductive structure can be excited by RF currents emitted from the slots of the first conductive structure which are in turn connected to feed contact pads and coupled to the radio circuit. 
         [0038]    Each of the first and second structures may individually comprise one or more slots. 
         [0039]    Now turning to the drawings,  FIG. 1   a  illustrates an embodiment of the prior art wherein an antenna  130  installed on a circuit board portion  110  of a wireless device. A shield can  100  is shown covering at least a portion of an electronic circuit for shielding purposes, and a transmission line  125  is used to connect the transceiver  120  to the antenna  130 .  FIG. 1   b  illustrates the assembled antenna system. Although the antenna system is functional, the antenna  130  consumes unnecessary space, resulting in a bulkier device volume. 
         [0040]      FIG. 2   a  illustrates two antennas  130   a;    130   b  being installed on the circuit board  110  of a wireless device. A shield can  100  is shown covering at least a portion of an electronic circuit for shielding purposes, and two transmission lines  125   a;    125   b  are used to connect the transceiver  120  to the antennas.  FIG. 2   b  is an assembled antenna system in accordance with  FIG. 2   a.  As can be recognized, multiple antenna schemes require a significant volume within the wireless device, especially considering the need to isolate the radiating antennas from the digital circuits of the wireless device. 
         [0041]      FIG. 3   a  illustrates an antenna integrated within a shield can. The shield can  200  includes a slot portion  210  etched within a surface thereof, the shield can is further adapted to contact with a feed pad  315  on the circuit board  300 ; the feed pad supplies an RF signal to the antenna  210  via a transmission line and feed pad  315 . The slot can be etched into the conductive shield can structure at a top surface, a side surface, or a combination thereof.  FIG. 3   b  illustrates the assembled antenna assembly in accordance with  FIG. 3   a.    
         [0042]      FIG. 4  illustrates multiple antennas integrated within a shield can. The shield can body  200  is adapted to contact a pair of feed pads on the circuit board  300 ; the feed pads supply RF signals to the two antennas  210   a;    210   b  formed by the slots. Transmission lines connect the feed pads  315   a;    315   b  to the transceiver  310 . The antennas may be positioned on one or more surfaces of the shield can structure, and can be positioned on opposite sides thereof, or alternatively may be positioned on adjacent sides of the shield can structure.  FIG. 4   b  illustrates an assembled antenna system in accordance with  FIG. 4   a.    
         [0043]      FIGS. 5(   a - b ) illustrate a comparison of a traditional two antenna topology ( FIG. 5   a ) on a circuit board and a shield can containing two slot antennas according to various embodiments herein. Integrating the antennas into the shield can results in a smaller circuit board, and smaller volume requirement, compared to the traditional antenna topology where discrete antennas are positioned on the circuit board. 
         [0044]    According to  FIG. 5   a,  a shield can  100  is provided to cover a transceiver and electronic circuit for shielding thereof. A first antenna  130   a  is positioned adjacent to a second antenna  130   b,  wherein each of the first and second antennas are connected to the transceiver via transmission lines. The antenna topology of  FIG. 5   a  requires a first volume of the circuit board and components. 
         [0045]    In contrast to  FIG. 5   a,    FIG. 5   b  illustrates two antennas being integrated within a shield can assembly according to various embodiments of the invention. The shield can assembly includes a shield can body  200  having two slot antennas  210   a;    210   b  embedded therein. The shield can is placed over the transceiver and circuit and forms contact with one or more feed contact pads on the circuit board  300 . As can be understood by those having skill in the art, the volume can be significantly reduced as depicted in  FIG. 5   b.    
         [0046]      FIGS. 6(   a - b ) illustrate a conductive structure being shaped to form a three dimensional structure  400 . In  FIG. 6   a,  two slots, including a first slot  430   a  and a second slot  430   b,  are formed along respective sides of the conductive structure. The conductive structure makes contact with two feed pads  515   a;    515   b  on the circuit board  510  for feeding an RF signal to the slot antennas.  FIG. 6   b  illustrates an assembled antenna system in accordance with  FIG. 6   a.    
         [0047]      FIG. 7  illustrates a conductive structure having internal walls, wherein slots  610   a;    610   b  are cut into the internal walls and excited for use as antennas for transmission and/or reception of radiated signals. The internal walls of the structure can be connected to a circuit board via one or more feed contact pads  620   a;    620   b.    
         [0048]      FIGS. 8(   a - b ) illustrate a multi-antenna, multi-shield, shield can assembly comprising a first shield can structure  200  and a conductive enclosure  700  configured to at least partially surround the shield can structure  200 . Each of the shield can  200  and conductive enclosure  700  comprises at least one slot  210   a - 210   b;    710   a - 710   b,  respectively, wherein the at least one slot of the shield can is electrically driven via a transmission line, and wherein the at least one slot of the conductive structure is configured for electromagnetic coupling with a slot of the adjacent shield can. The shield can makes contact with a pair of feed pads on the circuit board  800 ; the feed pads supply RF signals to the two antennas formed by the slots of the shield can. The conductive enclosure is positioned over the shield can. In essence, the conductive enclosure can be understood as a second shield can. One or multiple slots  710   a;    710   b  are cut into the conductive enclosure. Radiated signals from the slots cut into the first shield are configured to excite the slots cut into the second shield can, resulting in radiated signals. 
         [0049]      FIGS. 9(   a - d ) illustrate a number of examples of slot configurations that can be implemented in conductive structures such as shield cans and conductive enclosures as described herein. These examples are not limiting of the several variations possible, and are therefore not intended to be limiting in scope. One or multiple slots can be positioned on a top, side, or bottom surface of a conductive structure, or in a combination thereof. 
         [0050]      FIG. 10  illustrates an antenna integrated in a shield can assembly; the antenna comprises two slots  230   a;    230   b  etched from a first shield can  200 . The first shield can makes contact with a pair of feed pads on the circuit board; the feed pads supply RF signals to the two antennas formed by the slots. A conductive housing  1000  is positioned over the circuit board containing the first shield can  200 . One or multiple slots  1100   a;    1100   b  are etched from the conductive housing. Radiated signals from the slots etched from the first shield can are configured to excite the slots etched from the conductive housing, resulting in radiated signals of the housing. 
         [0051]    Thus, in accordance with the invention, an antenna system is integrated within a shield can. The antenna system comprises a circuit board having a radio circuit and an antenna contact pad thereon; a shield can formed by a conductive structure having a top surface and one or more side walls extending perpendicular therefrom, the shield can being connected to the circuit board at one or more of the side walls such that at least a portion of the radio circuit is surrounded by the shield can; and a slot etched into the shield can; the slot being coupled to the antenna contact pad of the circuit board; wherein the slot is adapted to radiate an electromagnetic signal. 
         [0052]    Moreover, an antenna system in another embodiment comprises a first conductive structure having a top surface and one or more sidewalls extending perpendicular therefrom; a second conductive structure having a top surface and one or more sidewalls extending perpendicular therefrom; a circuit board comprising a radio circuit; the first conductive structure further comprising a first slot etched therefrom, the first conductive structure being attached to the circuit board and configured to surround at least a portion of the radio circuit; the second conductive structure further comprising a second slot etched therefrom, the second conductive structure being attached to the circuit board and positioned surround at least a portion of the first conductive structure; wherein RF currents radiating from the first slot is adapted to excite the second slot for RF communication. 
         [0053]    In another aspect of the invention, a method comprises: (i) etching one or more first slots into a first conductive structure having a top surface and one or more side walls extending perpendicular therefrom to form a first shield can; (ii) providing at least one antenna feed contact on a circuit board for coupling with a slot of the first shield can; and (iii) assembling the shield can having a slot portion thereon with the circuit board such that the slot of the first shield can is adapted to radiate RF currents from a transceiver on the circuit board. 
         [0054]    In another embodiment, a method further comprises (iv) etching one or more second slots into a second conductive structure adapted to attach to the circuit board and surround at least a portion of the first shield can; (v) attaching the second conductive structure to the circuit board such that the one or more second slots are positioned adjacent to the one or more first slots of the first conductive structure such that RF currents emitted form the first slots are adapted to excite the second slots.