Patent Publication Number: US-9893429-B2

Title: Wideband slot antenna for wireless communication devices

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     BACKGROUND 
     Mobile nodes (MNs) may wirelessly transmit signals to corresponding components via an antenna. MN&#39;s may also comprise a cover, which may protect the antenna and/or other MN components during typical use. Such covers may be designed to look attractive to users and/or function as a trademark to distinguish a manufacturer&#39;s products. MN covers may comprise metallic elements. Positioning such metallic elements in close proximity to an antenna may result in reduced antenna transmission efficiency and or poor antenna reception. 
     SUMMARY 
     In one embodiment, the disclosure includes an antenna comprising a conductive base comprising a west edge, an east edge, a north edge, a south edge, and a center axis; a left slot of nonconductive material extending from the south edge toward the north edge and positioned between the west edge and the center axis, and a right slot of nonconductive material extending from the south edge toward the north edge and positioned between the east edge and the center axis. 
     In another embodiment, the disclosure includes a MN comprising an antenna configured to receive a current flow from a signal source wherein the current flow comprises a frequency, operate in a common mode if the current flow frequency is part of a first frequency range, operate in a left slot mode if the current flow frequency is part of a second frequency range, and operate in a right slot mode if the current flow frequency is part of a third frequency range. 
     In another embodiment, the disclosure includes a method comprising receiving a current flow from a signal source, operating in a common mode if the current flow comprises a frequency in a first range, operating in a left slot mode if the current flow comprises a frequency in a second range, and operating in a right slot mode if the current flow comprises a frequency in a third range. 
     These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. 
         FIG. 1  is a schematic diagram of an embodiment of an MN comprising a wideband slot antenna. 
         FIG. 2A  is an illustration of current flows in an embodiment of a wideband slot antenna operating in common mode. 
         FIG. 2B  is a schematic diagram of an electromagnetic field of an embodiment of a wideband slot antenna operating in common mode. 
         FIG. 3A  is an illustration of current flows in an embodiment of a wideband slot antenna operating in left slot mode. 
         FIG. 3B  is a schematic diagram of an electromagnetic field of an embodiment of a wideband slot antenna operating in left slot mode. 
         FIG. 4A  is an illustration of current flows in an embodiment of a wideband slot antenna operating in right slot mode. 
         FIG. 4B  is a schematic diagram of an electromagnetic field of an embodiment of a wideband slot antenna operating in right slot mode. 
         FIG. 5  is a flowchart of an embodiment of a method of transmitting a wireless signal. 
         FIG. 6  is a graph of radiation efficiency of an embodiment of a wideband slot antenna. 
         FIG. 7  is a perspective view of an embodiment of an MN cover. 
         FIG. 8  is a perspective view of an embodiment of another MN cover. 
         FIG. 9  is a schematic diagram of an embodiment of a MN. 
     
    
    
     DETAILED DESCRIPTION 
     It should be understood at the outset that, although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents. 
     Disclosed herein is a wideband slot antenna configured to transmit wireless signals despite being positioned in close proximity to metallic elements. The antenna may comprise a conductive base. The conductive base may comprise a left slot, a right slot, and a T slot of each comprising nonconductive material (e.g. air). The antenna may employ the conductive material of the conductive base in conjunction with the slots to operate in a common mode, a left slot mode, and a right slot mode. For example, when a current, such as a radio frequency (RF) signal with a frequency of less than about 1 Gigahertz (GHz) is applied to the antenna, the portion of the conductive base around the T slot may become active (e.g. common mode), which may result in a low frequency band transmission. As another example, when a RF signal with a frequency of about 1 GHz to about 2.04 GHz is applied to the antenna, the portion of the conductive base around the left slot may become active (e.g. left slot mode), which may result in a high frequency band transmission. As another example, when a RF signal with a frequency over about 2.05 GHz is applied to the antenna, the portion of the conductive base around the right slot may become active (e.g. right slot mode), which may result in another high frequency band transmission. The antenna may exhibit beneficial transmission characteristics in common mode, right slot mode, and/or left slot mode despite being position inside a metallic unibody cover, a cover comprising a metallic ring, a non-metallic cover, a cover comprising a non-metallic ring, and/or other covers. 
       FIG. 1  is a schematic diagram of an embodiment of an MN  160  comprising a wideband slot antenna  100 . The antenna  100  may comprise conductive material (e.g. a metallic base), and further comprise a north edge  101 , a south edge  102 , an east edge  103 , a west edge  104 , and a center axis  105 . The antenna may further comprise a left slot  120 , a right slot  110 , and a T slot  130 , each of which may comprise a nonconductive material (e.g. air). A person of ordinary skill in the art will understand that the presence of conductive material (e.g. the metallic base) and/or the absence of conductive material (e.g. slots  110 ,  120 , and/or  130 , respectively) may affect the electrical/transmission characteristics of antenna  100 . The right slot  110  may be positioned between the east edge  103  and the center axis  105 . The right slot  110  may form an opening  111  in the south edge  102 , a first channel  112  extending from the south edge opening  111  toward the north edge  101 , a second channel  113  extending from the first channel  112  toward the east edge  103 , a third channel  114  extending from the second channel  113  toward the north edge  101 , and a fourth channel  115  extending from the third channel  114  toward the center axis  105 , respectively. The left slot  120  may be positioned between the east edge  103  and the center axis  105 . The left slot  120  may form an opening  121  in the south edge  102 , a first channel  122  extending from the south edge opening  121  toward the north edge  101 , a second channel  123  extending from the first channel  122  toward the west edge  104 , a third channel  124  extending from the second channel  123  toward the north edge  101 , and a fourth channel  125  extending from the third channel  124  toward the center axis  105 , respectively. The T slot  130  may be positioned between left slot  120  and right slot  110 . The T slot  130  may form an opening  131  in the north edge  101  at or near the center axis  105 . The T slot  130  may further comprise a first channel  132  extending from the north edge opening  131  toward the south edge  102 , and a second channel  133  extending toward the west edge  104 , toward the east edge  103 , and through the first channel  132 . The first channel  132  may be substantially parallel to the center axis  105  and the second channel  133  may be positioned substantially perpendicular to the center axis  105 . 
     The antenna  100  may further comprise and/or be coupled to a signal feed  141  and a ground trace  142 . The signal feed  141  may be coupled to the north edge  101  between the north edge opening  131  and the fourth channel  115  of the right slot  110 . The ground trace  142  may be coupled to the north edge  101  between the north edge opening  131  and the fourth channel  125  of the left slot  120 . The signal feed  141  may be configured to receive electrical signals, such as RF signals, from a signal source, which may be positioned on board  153  (e.g. a printed circuit board (PCB)), and transmit the electrical signals toward the ground trace  142  via the conductive material of the antenna  100 . The electrical signal(s) may comprise an alternating current and may achieve resonance while traversing the antenna  100 , which may result in a portion of the electrical signals leaving the antenna  100  as a wireless transmission. The electrical signals may be described in terms of a wavelength, frequency, amplitude, etc. The frequency of the signals at a specified time may affect the behavior antenna  100  and associated electrical characteristics, as discussed below. For example, depending on the frequency of the electrical signal, the antenna may operate in common mode, left slot mode, and/or right slot mode as discussed with respect to  FIGS. 2A-2C, 3A-3B, and 4A-4B , respectively. 
     The antenna  100  may be positioned in a MN cover  150 . The cover  150  may comprise metallic elements, non-metallic elements, and/or combinations thereof. The cover  150  may be of any size large enough to contain the MN&#39;s  160  components. For example, the MN cover  150  may be about 130 millimeters (mm)×about 65 mm×about 8.9 mm. The MN cover  150  may comprise an east edge  152 , a west edge  151 , and a south edge  154 . The south edge  102  of the antenna  100  may be connected to the south edge  154  of the cover  150  in an area bounded by the left slot  120  and the right slot  110 . The south edge  102  of the antenna  100  may not be connected to the south edge of the cover  150  in an area extending between the left slot  120  and the west edge  104  of the antenna  100  and/or in an area extending between the right slot  120  and the east edge  103  of the antenna  100 . The cover  150  may further comprise slot openings that correspond to the left slot opening  121  and the right slot opening  111 . The distance between the west edge  151  of the cover  150  and the left slot opening  121  may be about 16.5 mm. The distance between the east edge  152  of the cover  150  and the right slot opening  111  may be also about 16.5 mm. The antenna  100  may also be positioned at least about 6 mm away from any other MN  160  components that comprise metallic materials, as metallic elements may have adverse effect on signal quality. 
     It should be noted that the terms north, south, east, west, left, and right are arbitrary terms as used herein and are employed solely to identify the antenna&#39;s  100  and/or MN&#39;s  160  components in a clear and logical manner. Such terms are not intended to imply any direction or orientation requirements for any components discussed herein. 
       FIG. 2A  is an illustration of current flows in an embodiment of a wideband slot antenna  100  operating in common mode. In  FIG. 2A  charge density associated with current flow(s) may be depicted as a plurality of dots. The antenna  100  may enter into common mode when receiving electrical signals with a frequency of less than about 1 GHz from a signal source. As shown in  FIG. 2A  when antenna  100  is in common mode, electrical current may flow between T slot  130  and the east edge  103  and between the T slot  130  and the west edge  104 . This may result in wireless transmission(s) emanating from both sides of antenna  100  (e.g. east/right side and west/left side, respectively). 
       FIG. 2B  is a schematic diagram of an electromagnetic field (E-field)  220  of an embodiment of a wideband slot antenna  100  operating in common mode (e.g. when receiving electrical signals with a frequency of less than about 1 GHz from a signal source.) When receiving electrical signals from a signal source, the antenna  100  may exhibit an E-field (such as E-field  220 ). E-field  220  may be represented by a plurality of arrows, which may illustrate the relative direction and magnitude of the E-Field  220  at various locations. The E-field may change based on the frequency of the electric signal and/or operating mode. E-field  220  may result when antenna  100  is operating in common mode. As shown in  FIG. 2B , antenna  100  may be positioned adjacent to a PCB  153 , which may act as a ground plane. When operating in common mode, E-Field  220  may extend away from the south edge and beyond the north edge in the direction of the PCB  153 . 
       FIG. 3A  is an illustration of current flows in an embodiment of a wideband slot antenna  100  operating in left slot mode. In  FIG. 3A  charge density associated with current flow(s) may be depicted as a plurality of dots. The antenna  100  may enter into left slot mode when receiving electrical signals from a signal source with a frequency of about 1 GHz to about 2.04 GHz. As shown in  FIG. 3A  when antenna  100  is in left slot mode, electrical current may flow primarily around the left slot  120 . This may result in wireless transmission(s) emanating from the west/left side of antenna  100 . Wireless signals may comprise a wavelength. The length of the left slot  120  (e.g. the cumulative length of the first channel  122 , second channel  123 , third channel  124 , and fourth channel  125 ), may be equal to about one quarter of the wavelength of the wireless signals emitted by the antenna  100  when in left slot mode. 
       FIG. 3B  is a schematic diagram of an E-field  320  of an embodiment of a wideband slot antenna  100  operating in left slot mode (e.g. when receiving electrical signals from a signal source with a frequency of about 1 GHz to about 2.04 GHz.) When operating in left slot mode, E-Field  320  may extend across the left slot  120 . As shown by the length of the arrows illustrating E-field  320 , the E-field may be stronger closer to the south edge  102  and weaker toward the north edge  101 . 
       FIG. 4A  is an illustration of current flows in an embodiment of a wideband slot antenna  100  operating in right slot mode. In  FIG. 4A  charge density associated with current flow(s) may be depicted as a plurality of dots. The antenna  100  may enter into right slot mode when receiving electrical signals from a signal source with a frequency of greater than about 2.05 GHz. As shown in  FIG. 4A  when antenna  100  is in right slot mode, electrical current may flow primarily around the right slot  110 . This may result in wireless transmission(s) emanating from the east/right side of antenna  100 . The length of the right slot  110  (e.g. the cumulative length of the first channel  112 , second channel  113 , third channel  114 , and fourth channel  115 ), may be equal to about one quarter of the wavelength of the wireless signals emitted by the antenna  100  when in right slot mode. 
       FIG. 4B  is a schematic diagram of an E-field of an embodiment of a wideband slot antenna  100  operating in right slot mode (e.g. when receiving electrical signals from a signal source with a frequency of greater than about 2.05 GHz.) When operating in right slot mode, E-Field  420  may extend across the right slot  110 . As shown by the length of the arrows illustrating E-field  420 , the E-field may be stronger closer to the south edge  102  and weaker toward the north edge  101 . 
       FIG. 5  is a flowchart of an embodiment of a method  500  of transmitting a wireless signal. Method  500  may be implemented by an antenna, such as antenna  100 . At step  510 , a current flow is received from a signal source. At step  520 , the method may determine the frequency of the current flow. If the current comprises a low frequency (e.g. less than about 1 GHz), the method may proceed to step  531  and operate in common mode by communicating the current around a T slot. If the current comprises a lower high frequency (e.g. between about 1 GHz and about 2.04 GHz), the method may proceed to step  532  and operate in left slot mode by communicating the current around a left slot. If the current comprises an upper high frequency (e.g. greater than about 2.05 GHz), the method may proceed to step  533  and operate in right slot mode by communicating the current around a right slot. 
       FIG. 6  is a graph  600  of radiation efficiency of an embodiment of a wideband slot antenna  100 . Graph  600  may compare radiation frequency measured in decibels (dB s) to wireless signal frequency measure in GHz. Radiation efficiency may the total power radiated by an antenna divided by the net power accepted by the antenna from a connected transmitter at a specified frequency. A radiation efficiency of between about −4 dB and about −6 dB may be beneficial for transmission of a specified wireless signal. As shown in  FIG. 6 , antenna  100  may maintain a radiation efficiency of between about −4 dB and about −6 dB over a broad range of wireless signal frequencies (e.g. about 0.7 GHz to about 0.75 GHz, about 0.77 GHz to about 0.96 GHz, about 1.62 GHz to about 1.65 GHz, about 1.7 GHz to about 1.8 GHz, about 2.15 GHz to about 2.25 GHz.) 
       FIG. 7  is a perspective view of an embodiment of an MN cover  700 . MN cover  700  may comprise a metallic unibody portion  740 , an upper non-metallic portion  731  (e.g. plastic, rubber, etc.), and a lower non-metallic portion  730  (e.g. plastic, rubber, etc.) Antenna  100  may be positioned inside MN cover  700  beneath the upper non-metallic portion  731  and/or the lower non-metallic portion  730 . In this configuration, the antenna  100  may be positioned inside a metallic unibody cover  740  while being positioned far enough from metallic elements to maintain the beneficial transmission characteristics as discussed above. MN cover  700  may comprise slots  710  and  720 , which may be positioned to connect to the first channel  111  of right slot  110  and the first channel  121  of left slot  120 , respectively. Slots  710  and  720  may be positioned about  16 . 5  mm from east edge  752  and west edge  751 , respectively. 
       FIG. 8  is a perspective view of an embodiment of another MN cover  800 . MN cover  800  may comprise a metallic ring  840  and a nonmetallic portion  830  (e.g. plastic, rubber, etc.) Antenna  100  may be positioned inside MN cover  800 , which may allow the antenna  100  to be positioned inside a metallic ring  840  while being positioned far enough from metallic elements to maintain the beneficial transmission characteristics as discussed above. MN cover  800  may also comprise slots  810  and  820 , which may be substantially similar to slots  810  and  820 , respectively. It should be noted that antenna  100  may also maintain the beneficial transmission characteristics as discussed above when positioned inside a non-metallic ring and/or non-metallic unibody structure. 
       FIG. 9  is a schematic diagram of an embodiment of a MN  900 , which may comprise antenna  100 , MN cover  700  and/or MN cover  800 . MN  900  may comprise a two-way wireless communication device having voice and/or data communication capabilities. In some aspects, voice communication capabilities are optional. The MN  900  generally has the capability to communicate with other computer systems on the Internet and/or other networks. Depending on the exact functionality provided, the MN  900  may be referred to as a data messaging device, a tablet computer, a two-way pager, a wireless e-mail device, a cellular telephone with data messaging capabilities, a wireless Internet appliance, a wireless device, a smart phone, a mobile device, or a data communication device, as examples. 
     MN  900  may comprise a processor  920  (which may be referred to as a central processor unit or CPU) that may be in communication with memory devices including secondary storage  921 , read only memory (ROM)  922 , and random access memory (RAM)  923 . The processor  920  may be implemented as one or more general-purpose CPU chips, one or more cores (e.g., a multi-core processor), or may be part of one or more application specific integrated circuits (ASICs) and/or digital signal processors (DSPs). The processor  920  may be implemented using hardware, software, firmware, or combinations thereof. 
     The secondary storage  921  may be comprised of one or more solid state drives and/or disk drives which may be used for non-volatile storage of data and as an over-flow data storage device if RAM  923  is not large enough to hold all working data. Secondary storage  921  may be used to store programs that are loaded into RAM  923  when such programs are selected for execution. The ROM  922  may be used to store instructions and perhaps data that are read during program execution. ROM  922  may be a non-volatile memory device may have a small memory capacity relative to the larger memory capacity of secondary storage  921 . The RAM  923  may be used to store volatile data and perhaps to store instructions. Access to both ROM  922  and RAM  923  may be faster than to secondary storage  921 . 
     MN  900  may be any device that communicates data (e.g., packets) wirelessly with a network. The MN  900  may comprise a receiver (Rx)  912 , which may be configured for receiving data, packets, or frames from other components. The receiver  912  may be coupled to the processor  920 , which may be configured to process the data and determine to which components the data is to be sent. The MN  900  may also comprise a transmitter (Tx)  932  coupled to the processor  920  and configured for transmitting data, packets, or frames to other components. The receiver  912  and transmitter  932  may be coupled to an antenna  930 , which may be configured to receive and transmit wireless (radio) signals. As an example, antenna  930  may comprise and/or be substantially similar to antenna  100 . As another example, Tx  932  may comprise and/or be substantially similar to an electrical/RF signal source as discussed above. 
     The MN  900  may also comprise a device display  940  coupled to the processor  920 , for displaying output thereof to a user. The device display  920  may comprise a light-emitting diode (LED) display, a Color Super Twisted Nematic (CSTN) display, a thin film transistor (TFT) display, a thin film diode (TFD) display, an organic LED (OLED) display, an active-matrix OLED display, or any other display screen. The device display  940  may display in color or monochrome and may be equipped with a touch sensor based on resistive and/or capacitive technologies. 
     The MN  900  may further comprise input devices  941  coupled to the processor  920 , which may allow a user to input commands to the MN  900 . In the case that the display device  940  comprises a touch sensor, the display device  940  may also be considered an input device  941 . In addition to and/or in the alternative, an input device  941  may comprise a mouse, trackball, built-in keyboard, external keyboard, and/or any other device that a user may employ to interact with the MN  900 . The MN  900  may further comprise sensors  950  coupled to the processor  920 . Sensors  950  may detect and/or measure conditions in and/or around MN  900  at a specified time and transmit related sensor input and/or data to processor  920 . 
     At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R 1 , and an upper limit, Ru, is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R 1 +k*(R u −R 1 ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 7 percent, . . . , 70 percent, 71 percent, 72 percent, . . ., 97 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. The use of the term “about” means ±10% of the subsequent number, unless otherwise stated. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. The discussion of a reference in the disclosure is not an admission that it is prior art, especially any reference that has a publication date after the priority date of this application. The disclosure of all patents, patent applications, and publications cited in the disclosure are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to the disclosure. 
     While several embodiments have been provided in the present disclosure, it may be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented. 
     In addition, techniques, systems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and may be made without departing from the spirit and scope disclosed herein.