Patent Publication Number: US-2010127942-A1

Title: Weight-Tapered IL Antenna with Disc Loaded

Description:
BACKGROUND  
     The capabilities of mobile communications devices are consistently increasing. Typical modern devices may require high levels of performance in transmitting and receiving wireless signals. However, devices may also be designed to minimize their size. Thus, antennas should be designed as to optimize performance in terms of bandwidth and radiation efficiency while minimizing their size. 
     SUMMARY OF THE INVENTION  
     The present invention is directed to an antenna including a main span extending in a first direction, a first arm extending from the main span in a second direction, a second arm extending from the main span in a third direction, and a disc portion joined to the main span. 
     The present invention is further directed to a device including a wireless transceiver and an antenna coupled to the wireless transceiver. The antenna includes a main span extending in a first direction, a first arm extending from the main span in a second direction, a second arm extending from the main span in a third direction, and a disc portion joined to the main span. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         FIG. 1  shows an exemplary mobile communication device according to the present invention. 
         FIG. 2  shows an exemplary antenna with a disc-shaped portion according to the present invention. 
     
    
    
     DETAILED DESCRIPTION  
     The exemplary embodiments of the present invention may be further understood with reference to the following description and the appended drawings, wherein like elements are referred to with the same reference numerals. The exemplary embodiments describe antennas that improve bandwidth and radiation efficiency performance. 
     One important design concern in the development of modern mobile computing and communication devices is the reduction of space used by various components in order to minimize the overall size of devices. Like other components, it is desirable to reduce the space occupied by antennas without sacrificing performance. Commonly, inverted-L antennas may be used, but it may be desirable to improve the bandwidth and gain compared to such antennas. Other design concerns in antenna development include maximizing radiation efficiency in occupied bands and maintaining satisfactory performance when the distance between radiated elements decreases as the overall size of mobile devices decreases. 
       FIG. 1  illustrates an exemplary device  100  according to the present invention. The device  100  is shown with part of its casing  110  removed in order to illustrate internal components. The device  100  includes a first antenna  120  and a second antenna  130  that are disposed on a double-sided copper-plated substrate. In one exemplary embodiment, the substrate may be 0.762 mm thick with copper plating 0.0175 mm thick. The substrate may have a dielectric constant of 3.66 and a dissipation factor of 0.0035, and may be, for example, an RO4350B backing manufactured by the Rogers Company. The antennas  120  and  130  pass through the substrate via ports  140  and  142 , respectively. Those of skill in the art will understand that each of the antennas  120  and  130  may be connected to a transceiver, not shown (e.g., a cellular transceiver, a Bluetooth transceiver, a WiFi transceiver, etc.). Further, those of skill in the art will understand that while this exemplary embodiment includes antennas  120  and  130  of substantially the same design and differing scale, various other devices may have a plurality of antennas that differ from one another in order to best suit the needs of various types of transceivers. For example, in another exemplary embodiment, the first antenna  120  may be substantially as described below, while the second antenna  130  may be a tapered-edge inverted L-type antenna. 
     Additionally, while the antennas  120  and  130  are depicted with the same orientation, other devices may orient antennas at an angle to one another in order to obtain better signal isolation. The first antenna  120  and the second antenna  130  share a common ground plane, but may have differing ground planes in other embodiments. The exemplary antennas  120  and  130  may be comprised of gold plating disposed on the copper substrate described above. In one exemplary embodiment, the plating may be a blend of nickel and gold with nickel plating of 0.003 mm thickness and gold plating of 0.00015 mm thickness. The leads of the antennas  120  and  130  may be spaced 35 mm apart on the substrate  140 . 
       FIG. 2  shows the first antenna  120  in more detail. The first antenna  120  includes a main span  121 , a first arm  122 , a second arm  123 , a disc-shaped portion (“disc”)  124 , and a lead  125 . The length of the main span  121  may be 37.64 mm from its intersection with the lead  125  to the center of the disc  124 ; its width may be 8.281 mm. The first arm  122  has a substantially tapered tip that is truncated near its base. The longest side of the first arm  122  may be 24.84 mm in length. The second arm  123  is also substantially tapered, and the longest side thereof may be 30.54 mm in length. Those of skill in the art will understand that the shapes of the arms  122  and  123  are only exemplary, and that other projection profiles may also be possible. The lead  125  may be 1.681 mm in width and may connect main span  121  to port  140 . 
     The first antenna  120  further includes a disc-shaped portion  124 . The disc  124  is centered substantially at the intersection of the main span  121  and the second arm  123 , and may have a radius of 12 mm. It may abut the casing  110  of the device  100 . The disc  124  may hold charges and thus enhance the sending/receiving properties of the main span  120  of the first antenna  120 , such as the bandwidth impedance, particularly in higher bands. This enhancement may be accompanied by a minor decrease in efficiency. Those of skill in the art will understand that the dimensions described above are only exemplary and that the dimensions of other exemplary embodiments may vary from those provided. 
     The first antenna  120  may be used, for example, with a transceiver in the cellular band (e.g., AMPS, GSM, DCS, PCS, UMTS, etc.). In such frequencies, it may achieve a bandwidth of 23%, a significant improvement of the bandwidth range of 5% to 12% typically achieved by monopole or dipole antennas. As discussed above, in this exemplary embodiment, the second antenna  130  may be similar to the first antenna  120  but of smaller scale. The scale may be one-third in this exemplary embodiment but may vary in other embodiments. The second antenna  130  may be used, for example, with a WiFi (e.g., 802.11a/b/g) transceiver. Like the first antenna  120 , the second antenna may achieve a bandwidth of 23%, a significant improvement over typical monopole/dipole antennas. 
     Both the first antenna  120  and the second antenna  130  may have omni-directional radiation patterns. At the ports  140  and  142 , the voltage standing wave ratio may be less than 1:2.5 across the entire band. The first antenna  120  may achieve an efficiency of at least 80% in the AMPS and GSM frequency bands, 70% in the DCS and PCS frequency bands, and 60% in the UMTS frequency band. The second antenna  130  may achieve an efficiency of at least 90% in the WiFi 802.1b/g bands and at least 55% in the WiFi 802.11a band. 
     It will be apparent to those skilled in the art that various modifications may be made in the present invention, without departing from the spirit or the scope of the invention. For example, the principles described may be applied to antennas adapted to send and receive signals in various frequency bands and for various purposes. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.