Abstract:
A transceiver, including a multi-layer printed circuit board including a layer that serves as a first ground plane, and an antenna for transmitting and receiving radio signals, a second ground plane, and at least one ground contact for connecting the first ground plane and the second ground plane, wherein the first ground plane is too short for the antenna to resonate at a desired frequency, but the first and second ground planes, when connected, provide a combined ground plane sufficient for the antenna to resonate at the desired frequency.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Application No. 61/180,894, entitled ANTENNA WITH DIVIDED GROUND PLANE, filed on May 25, 2009 by inventors Sagiv Zeltser and Yohan Cohen. 
    
    
     FIELD OF THE INVENTION 
     The field of the present invention is antennas for wireless communication devices. 
     BACKGROUND OF THE INVENTION 
     One of the many challenges in miniaturization of wireless communication devices is the lack of a sufficiently large ground plane for an antenna. 
     As described in US Publication No. 2008/0252536 A1 to Anguera et al., a conventional antenna set for a portable wireless communication device, such as a cell phone, includes an antenna element and a ground plane. The communication device includes a multi-layer printed circuit board (PCB), one of the layers of which serves as a ground plane for the antenna. 
     Design of an antenna set is done in conjunction with development of the communication device. Antenna design is based inter alia on form factor of the communication device, PCB layout, and location of different elements, especially metallic elements such as hinges, rails, cables, audio lines, LCD and battery. The antenna set is calibrated by performance testing that recursively tests modifications in the antenna with the hardware and the form factor of the communication device. The antenna set is performance tested in several scenarios, with different hand positionings of the phone and fingers covering the antenna. 
     In order for the antenna to perform well, in terms of its bandwidth, efficiency and gain, the ground plane must be sufficiently large relative to the wavelengths of the frequencies of operation of the antenna. But as the size of the communication device shrinks, the size of the ground plane is correspondingly reduced, yet the frequencies of operation of the antenna must remain substantially unchanged. As such, performance of the antenna degrades. 
     SUMMARY OF THE DESCRIPTION 
     Aspects of the present invention relate to miniature communication devices that use extended ground planes to achieve required antenna performance. An antenna and a first ground plane for the antenna are housed within a modular communication device. A second ground plane, which extends the first ground plane, is housed within a jacket into which the modular communication device is inserted, or to which the modular communication device is attached. Additional extended ground planes may be used, as appropriate. 
     Embodiments of the present invention include inter alia a tiny communicator module that inserts into or attaches to a variety of different devices, to provide the devices with cell phone, short messaging service (SMS) and other communication functionality. Examples of such devices include cameras, MP3 players, digital picture frames, clocks, and a huge assortment of consumer electronic devices that can all benefit from wireless communication. 
     There is thus provided in accordance with an embodiment of the present invention a transceiver, including a multi-layer printed circuit board including a layer that serves as a first ground plane, and an antenna for transmitting and receiving radio signals, a second ground plane, and at least one ground contact for connecting the first ground plane and the second ground plane, wherein the first ground plane is too short for the antenna to resonate at a desired frequency, but the first and second ground planes, when connected, provide a combined ground plane sufficient for the antenna to resonate at the desired frequency. 
     There is additionally provided in accordance with an embodiment of the present invention a modular communicator including an antenna for transmitting and receiving radio waves, a ground plane for the antenna, a power amplifier to amplifying signals received by said antenna, a modem for transmitting and receiving data via the antenna, and at least one ground contact, for connecting the ground plane to an extended ground plane housed within a removable jacket for the modular communicator, wherein the ground plane is too short for the antenna to resonate at a desired frequency, but the ground plane when connected with the extended ground plane, provides a combined ground plane sufficient for the antenna to resonate at the desired frequency. 
     There is further provided in accordance with an embodiment of the present invention a removable jacket for a modular communicator, including an extended ground plane for an antenna, and at least one ground contact, for connecting the extended ground plane to a ground plane for a communicator that houses the antenna, wherein the ground plane is too short for the antenna to resonate at a desired frequency, but the ground plane when connected with the extended ground plane, provides a combined ground plane sufficient for the antenna to resonate at the desired frequency. 
     There is yet further provided in accordance with an embodiment of the present invention a communication system, including a modular communicator, including an antenna for transmitting and receiving radio waves, a ground plane for the antenna, a power amplifier to amplifying signals received by the antenna, a modem for transmitting and receiving data via the antenna, and at least one ground contact, for connecting the ground plane to a jacket for the modular communicator, and a removable jacket for the modular communicator, including an extended ground plane for the antenna, wherein the ground plane is too short for the antenna to resonate at a desired frequency, but the ground plane and the extended ground plane, when the modular communicator and the removable jacket are connected, provide a combined ground plane sufficient for the antenna to resonate at the desired frequency. 
     There is moreover provided in accordance with an embodiment of the present invention a transceiver, including a multi-layer printed circuit board including a layer that serves as a first ground plane, and an antenna for transmitting and receiving radio signals, a second ground plane, and at least one ground contact for connecting the first ground plane and the second ground plane, wherein the first ground plane is too short for the antenna to resonate efficiently, but the first and second ground planes, when connected, provide a combined ground plane that resonates with greater efficiency. 
     There is additionally provided in accordance with an embodiment of the present invention a modular communicator including an antenna for transmitting and receiving radio waves, a ground plane for the antenna, a power amplifier to amplifying signals received by the antenna, a modem for transmitting and receiving data via the antenna, and at least one ground contact, for connecting the ground plane to an extended ground plane housed within a removable jacket for the modular communicator, wherein the ground plane is too short for the antenna to resonate efficiently, but the ground plane when connected with the extended ground plane, provides a combined ground plane that resonates with greater efficiency. 
     There is further provided in accordance with an embodiment of the present invention a removable jacket for a modular communicator, including an extended ground plane for an antenna, and at least one ground contact, for connecting the extended ground plane to a ground plane for a communicator that houses the antenna, wherein the ground plane is too short for the antenna to resonate efficiently, but the ground plane when connected with the extended ground plane, provides a combined ground plane that resonates with greater efficiency. 
     There is yet further provided in accordance with an embodiment of the present invention a communication system, including a modular communicator, including an antenna for transmitting and receiving radio waves, a ground plane for the antenna, a power amplifier to amplifying signals received by the antenna, a modem for transmitting and receiving data via the antenna, and at least one ground contact, for connecting the ground plane to a jacket for the modular communicator, and a removable jacket for the modular communicator, including an extended ground plane for the antenna, wherein the ground plane is too short for the antenna to resonate efficiently, but the ground plane and the extended ground plane, when the modular communicator and said removable jacket are connected, provide a combined ground plane that resonates with greater efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings in which: 
         FIG. 1  is a simplified block diagram of two configurations for an antenna with a divided ground plane, in accordance with embodiments of the present invention; 
         FIG. 2  is a simplified diagram of a printed circuit board with an antenna that uses a divided ground plane, in accordance with an embodiment of the present invention; 
         FIG. 3  is an illustration of a communication system constructed and operative in accordance with an embodiment of the present invention; 
         FIG. 4  is an illustration of a modular communicator being inserted into a jacket, in accordance with an embodiment of the present invention; and 
         FIG. 5  is a simplified block diagram of a modular communicator and a jacket in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present invention relate to a wireless communicator antenna that uses a ground plane that is divided into at least two smaller ground planes, one of which is a component of the communicator and others of which are components of a jacket for the communicator. When the communicator is inserted into or attached to the jacket, the smaller ground planes join to form a combined ground plane for the antenna. 
     Reference is made to  FIG. 1 , which is a simplified block diagram of two configurations,  100 A and  100 B, for an antenna with a divided ground plane, in accordance with embodiments of the present invention. Shown in  FIG. 1  is an antenna  110  mounted on a multi-layer printed circuit board (PCB), one layer of which is a ground plane  120 . However, the ground plane  120  may not be long enough for antenna  110  to resonate at a desired frequency. An extended ground plane  130  is connected to ground plane  120  via ground contacts  140 . The combined ground planes  120  and  130  provide the necessary ground plane length for antenna  110  to resonate at the desired frequency. 
     Even if ground plane  120  is long enough for antenna  110  to resonate at the desired frequency, the efficiency of the resonance may be low. In this case, ground plane  130  serves to improve the efficiency of the resonance. 
     In configuration  100 A the ground planes  120  and  130  are co-planar, and form a straight combined ground plane. In configuration  100 B the ground planes  120  and  130  are skewed, and form a dihedral angle less than 180°. 
     For each configuration  100 A and  100 B, empirical tests have been performed on several parameters, as indicated in TABLE I. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE I 
               
             
             
               
                   
               
               
                 Parameter ranges for configurations 100A and 100B 
               
             
          
           
               
                   
                 Parameter 
                 Range 
               
               
                   
                   
               
               
                   
                 Lengths of ground planes 120 and 130 
                  20 mm-100 mm 
               
               
                   
                 Widths of ground contacts 140 
                 0 mm-2 mm 
               
               
                   
                 Lengths of ground contacts 140 
                 0 mm-2 mm 
               
               
                   
                 Number of ground contacts 140 
                 1-2 
               
               
                   
                 Gap between ground contacts 140 
                  0 mm-14 mm 
               
               
                   
                   
               
             
          
         
       
     
     Reference is made to  FIG. 2 , which is a simplified diagram of a printed circuit board with an antenna that uses a divided ground plane, in accordance with an embodiment of the present invention. 
     Aspects of the present invention relate to a modular wireless communicator that inserts into or attaches to a “jacket”. A jacket is defined herein to mean a component that the communicator inserts into or attaches to, and thereby extends the surface of the antenna to improve its functionality. A jacket may be a device that provides an enhanced user interface for the communicator. A jacket may be a device that enriches the capabilities of the communicator. A jacket may or may not be able to operate independently when the communicator is not connected thereto. 
     In accordance with an embodiment of the present invention, antenna  110  and ground plane  120  are housed within the communicator, and extended ground plane  130  is housed within the jacket. As such, when the communicator is inserted into or attached to the jacket, antenna  110  is able to operate in conjunction with the combined ground plane. 
     Ground contacts  140  may be embedded within connectors of the communicator and the jacket. Ground contacts  140  may alternatively be embedded within shieldings of such connectors. Ground contacts  140  may yet alternatively be embedded at any other dedicated contact points between the communicator and the jacket, including inter alia metal springs and protrusions. Ground contacts  140  may yet alternatively be embedded at any other mechanical contact that is made when the communicator is inserted into or attached to the jacket. 
     In some embodiments of the present invention, close proximity yields electromagnetic contact between the ground planes via capacitive coupling, without the need for physical contact. 
     Reference is made to  FIG. 3 , which is an illustration of a communication system constructed and operative in accordance with an embodiment of the present invention. Shown in  FIG. 3  are a plurality of modular wireless communicators  200   a - 200   c , including 2.5G cell phones for a GSM network, 3G cell phones for GSM network, and CDMA cell phones for a CDMA network. It will be appreciated by those skilled in the art that the networks illustrated in  FIG. 3  are exemplary of a wide variety of networks and communication protocols that are supported by the modular communicators of the present invention, such networks and communication protocols including inter alia WiFi, Bluetooth and WiMax. 
     Also shown in  FIG. 3  is a plurality of jackets  300   a - 300   h . In accordance with an embodiment of the present invention, each communicator  200   a - 200   c  may be inserted into or attached to any of jackets  300   a - 300   h , so as to operate in combination therewith. Communicators  200   a - 200   c  are substantially of the same form factor and, as such, are able to be inserted into each of jackets  300   a - 300   h.    
     Reference is further made to  FIG. 4 , which is an illustration of a modular communicator  200  being inserted into a jacket  300 , in accordance with an embodiment of the present invention. Jacket  300  as shown in  FIG. 3  includes a hollow cavity at the top for insertion of communicator  200  therein. 
     Reference is made to  FIG. 5 , which is a simplified block diagram of communicator  200  and jacket  300  in accordance with an embodiment of the present invention. Communicator  200  includes antenna  110  and ground plane  120 . In addition, communicator  200  generally includes seven primary components, as follows: a controller  210 , a modem  220  for sending and receiving voice and data, a user interface  230 , a memory storage  240 , a power amplifier  260 , a connector  280  for connecting the communicator to jacket  300  when the communicator is inserted into jacket  300 , and a subscriber identification module (SIM)  290 . 
     Controller  210  executes programmed instructions that control the data flow between communicator  200  and jacket  300 . Modem  220  controls the communication functionality of communicator  200 . User interface  230  includes a display screen  231  and a keypad  232 . User interface  230  may optionally include additional components (not shown) such as a microphone, a headset audio jack, an earpiece, a mono speaker or stereo speakers, and a vibrator. 
     Power amplifier  260  includes a radio frequency (RF) interface  265 , and is connected to antenna  110 . 
     In accordance with an embodiment of the present invention, the interface between controller  210  and storage  240 , and the interface between controller  210  and modem  220  are both SD interfaces. The interface between controller  210  and connector  280  is a custom interface. 
     Communicator  200  may also include an optional power management subsystem  250 , which includes charging circuitry for charging a battery  255 . 
     In some embodiments of the present invention, communicator  200  may be missing some of the components shown in  FIG. 5 , such as display screen  231  or keypad  232 . 
     Jacket  300  includes extended ground plane  130 , and may include additional extended ground planes, as appropriate. In addition, jacket  300  generally includes four primary components, as follows: a controller  310 , a user interface  330 , a memory storage  340 , and a connector  380  for connecting the jacket to communicator  200  when communicator  200  is inserted into the jacket. Jacket  300  may also include an optional power management subsystem  350  and an optional battery  355 . 
     User interface  330  includes a display screen  331  and a keypad  532 . User interface  330  may optionally include additional components (not shown), such as a microphone, a headset audio jack, an earpiece, a mono speaker or stereo speakers, and a vibrator. 
     In accordance with an embodiment of the present invention, the interface between controller  310  and storage  340  is an SD interface. The interface between controller  310  and connector  380  is a custom interface. 
     When communicator  200  is inserted into or attached to jacket  300 , ground plane  120  and extended ground plane  130  form a combined ground plane for antenna  110 . 
     In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made to the specific exemplary embodiments without departing from the broader spirit and scope of the invention as set forth in the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense.