PATENT DOCUMENT

Publication Number: US-9793616-B2
Application Number: US-201213681138-A
Country: US
Kind Code: B2

Title: Shared antenna structures for near-field communications and non-near-field communications circuitry

Abstract:
Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include conductive housing structures such as a peripheral conductive housing member. The antenna structures may be based on an inverted-F antenna resonating element or other types of antenna resonating element. An electronic device may have near field communications circuitry and non-near-field communications circuitry such as cellular telephone, satellite navigation system, or wireless local area network transceiver circuitry. Antenna structures may be configured to handle signals associated with the non-near-field communications circuitry. The antenna structures may also have portions that form a near field communications loop antenna for handling signals associated with the near field communications circuitry.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 an inverted-F antenna resonating element; 
 an antenna ground that is separated from the inverted-F antenna resonating element by an opening; 
 a first path that is coupled between the antenna ground and the inverted-F antenna resonating element and that spans the opening; 
 a second path that is coupled between the antenna ground and the inverted-F antenna resonating element and that spans the opening; 
 an antenna feed path that is coupled to the inverted-F antenna resonating element; 
 non-near-field communications circuitry coupled to the antenna feed path that transmits and receives signals in a non-near-field communications signal band in which the second path forms a short circuit across the opening and serves as a return path for the inverted-F antenna resonating element and in which the first path forms an open circuit; and 
 near field communications circuitry coupled to the antenna feed path that transmits and receives near field communications in a near field communications band in which the first path forms a short circuit across the opening and serves as a portion of a near field communications loop antenna and in which the second path forms an open circuit. 
 
     
     
       2. The electronic device defined in  claim 1  further comprising a conductive peripheral housing member that surrounds a peripheral edge of the electronic device, wherein the inverted-F antenna resonating element is formed from a segment of the conductive peripheral housing member. 
     
     
       3. The electronic device defined in  claim 1  wherein an inductor is interposed on the first path. 
     
     
       4. The electronic device defined in  claim 3  wherein the first path has a first end that is coupled to the inverted-F antenna resonating element and a second end that is coupled to the antenna ground. 
     
     
       5. The electronic device defined in  claim 4  wherein the inverted-F antenna resonating element includes a portion of a conductive peripheral housing member that surrounds a peripheral edge of the electronic device. 
     
     
       6. The electronic device defined in  claim 1  further comprising a capacitor interposed on the second path. 
     
     
       7. The electronic device defined in  claim 4  further comprising a duplexer, wherein the duplexer has a feed port coupled to the antenna feed path, a near field communications port coupled to the near field communications circuitry, and a non-near-field communications port coupled to the non-near-field communications circuitry. 
     
     
       8. The electronic device defined in  claim 7  wherein the non-near-field communications circuitry comprises cellular telephone transceiver circuitry and the non-near-field communications signal band comprises a cellular telephone band above 700 MHz. 
     
     
       9. The electronic device defined in  claim 8  wherein the near field communications circuitry is configured to operate in a near field communications band at 13.56 MHz. 
     
     
       10. The electronic device defined in  claim 7  wherein the duplexer has a first path that is coupled between the antenna feed path and the near field communications circuitry and has a second path that is coupled between the antenna feed path and the non-near-field communications circuitry, and the duplexer comprises an inductor in the first path and a capacitor in the second path. 
     
     
       11. Antenna structures in an electronic device having a length, a width, and a height, the antenna structures comprising:
 an inverted-F antenna resonating element formed from metal structures, wherein the metal structures extend across the width and the height of the electronic device; 
 an antenna ground that is separated from the metal structures by an opening; 
 an antenna feed path that is coupled to the inverted-F antenna resonating element, wherein the inverted-F antenna resonating element and antenna ground are configured to exhibit an antenna resonance in a communications band above 700 MHz and at least part of the metal structures form a near field communications loop antenna that is configured to transmit near field communications signals in a near field communications band; 
 a first path coupled between the inverted-F antenna resonating element and the antenna ground across the opening; and 
 a second path coupled between the inverted-F antenna resonating element and the antenna ground across the opening, wherein the first path forms a short circuit across the opening that forms a portion of the near field communications loop antenna and the second path forms an open circuit in the near field communications band, and the second path forms a short circuit across the opening that forms a return path for the inverted-F antenna resonating element and the first path forms an open circuit in the communications band above 700 MHz. 
 
     
     
       12. The antenna structures defined in  claim 11  wherein the near field communications band comprises a 13.56 MHz band and wherein the metal structures comprise metal electronic device housing structures. 
     
     
       13. The electronic device defined in  claim 2 , wherein the segment of the conductive peripheral housing member forms at least one exterior surface of the electronic device. 
     
     
       14. The electronic device defined in  claim 13 , wherein the electronic device has a length, a width that is less than the length, and a height that is less than the width, and the segment of the conductive peripheral housing member extends across the width and the height of the electronic device. 
     
     
       15. The electronic device defined in  claim 14 , wherein the segment of the conductive peripheral housing member comprises first, second, and third portions, the first portion extends across the width of the electronic device, and the second and third portions extend parallel to the length of the electronic device. 
     
     
       16. The electronic device defined in  claim 15 , wherein the second portion is separated from the antenna ground structures by a first dielectric gap in the conductive peripheral housing member and the third portion is separated from the antenna ground structures by a second dielectric gap in the conductive peripheral housing member. 
     
     
       17. The electronic device defined in  claim 1 , wherein the electronic device has a length, a width that is less than the length, and a height that is less than the width, the inverted-F antenna resonating element includes a portion of a conductive peripheral housing member that runs along a periphery of the electronic device, the portion of the conductive peripheral housing member extends across the width and the height of the electronic device, and the antenna ground extends across the width of the electronic device. 
     
     
       18. The electronic device defined in  claim 10 , further comprising:
 a first impedance matching circuit coupled between the inductor and the near field communications circuitry; and 
 a second impedance matching circuit that is separate from the first impedance matching circuit coupled between the capacitor and the non-near-field communications circuitry. 
 
     
     
       19. The antenna structures defined in  claim 11 , wherein an inductor is interposed in the first path and a capacitor is interposed in the second path. 
     
     
       20. The electronic device defined in  claim 1 , wherein the second path is interposed between the antenna feed path and the first path. 
     
     
       21. The electronic device defined in  claim 20  further comprising a conductive peripheral housing member that surrounds a peripheral edge of the electronic device, wherein the inverted-F antenna resonating element is formed from a segment of the conductive peripheral housing member.

Description:
BACKGROUND 
     This relates generally to electronic devices, and more particularly, to antennas for electronic devices with wireless communications circuitry. 
     Electronic devices such as portable computers and cellular telephones are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry such as cellular telephone circuitry to communicate using cellular telephone bands. Electronic devices may use short-range wireless communications circuitry such as wireless local area network communications circuitry to handle communications with nearby equipment. Electronic devices may also be provided with satellite navigation system receivers and other wireless circuitry such as near field communications circuitry. Near field communications schemes involve electromagnetically coupled communications over short distances, typically 20 cm or less. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to implement wireless communications circuitry such as antenna components using compact structures. At the same time, there is a desire for wireless devices to cover a growing number of communications bands. For example, it may be desirable for a wireless device to cover a near field communications band while simultaneously covering additional non-near-field (far field) bands such cellular telephone bands, wireless local area network bands, and satellite navigation system bands. 
     Because antennas have the potential to interfere with each other and with components in a wireless device, care must be taken when incorporating antennas into an electronic device. Moreover, care must be taken to ensure that the antennas and wireless circuitry in a device are able to exhibit satisfactory performance over a range of operating frequencies. 
     It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless electronic devices. 
     SUMMARY 
     Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. The radio-frequency transceiver circuitry may include near field communications circuitry that operates in a near field communications band. The radio-frequency transceiver circuitry may also include non-near-field-communications circuitry (far field communications circuitry) such as such as cellular telephone, satellite navigation system, or wireless local area network transceiver circuitry. The non-near-field communications circuitry may operate in one or more non-near-field communications bands. 
     The antenna structures may include conductive housing structures such as a peripheral conductive housing member. The antenna structures may be based on an inverted-F antenna resonating element or may have other types of antenna resonating element. The antenna structures may be configured to handle signals associated with the non-near-field communications circuitry such as cellular telephone signals, satellite navigation system signals, or wireless local area network signals. The antenna structures may also be used to form a near field communications loop antenna. The near field communications loop antenna may handle signals associated with the near field communications circuitry. Sharing the antenna structures between near field and non-near-field applications allows device size to be minimized. 
     Antenna structures may be provided with paths that form multiple loops for the loop antenna. The loops may be formed at different locations within an inverted-F antenna resonating element or may be concentric. 
     Antenna structures may be formed at opposing ends of an electronic device. Combining circuitry may allow the near field communications circuitry and the non-near-field communications circuitry to be coupled to common antenna structures. In configurations for an electronic device that include antenna structures at opposing ends of the device, near field communications signals may be transmitted and received at both ends of the device. Near field communications signals may also be transmitted from front and rear faces of an electronic device. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of illustrative electronic device wireless circuitry in accordance with an embodiment of the present invention. 
         FIG. 4  is a diagram of illustrative antenna structures coupled to near field communications circuitry and non-near-field-communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram of illustrative antenna structures coupled to near field communications circuitry and non-near-field communications circuitry using coupling circuitry such as a duplexer in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of illustrative antenna structures in a configuration in which near field communications circuitry and non-near-field communications circuitry are coupled to the antenna structures and in which the antenna structures form multiple loops at different locations within the antenna structures when operating at near field communications frequencies in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram of illustrative antenna structures in a configuration in which near field communications circuitry and non-near-field communications circuitry are coupled to the antenna structures and in which the antenna structures form a multi-turn loop antenna when operated at near field communications frequencies in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram of an illustrative electronic device having multiple antennas such as antennas located at opposing ends of a device housing and having circuitry that allows near field communications circuitry and non-near-field-communications circuitry to use the antennas in accordance with an embodiment of the present invention. 
         FIG. 9  is a cross-sectional diagram of an illustrative electronic device of the type shown in  FIG. 8  showing how antenna signals may be emitted and received from both ends of the device and from both front and rear faces of the device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support wireless communications in multiple wireless communications bands. The wireless communications circuitry may include antenna structures such as antenna structures that include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. 
     Antenna structures may, if desired, be formed from conductive electronic device structures. The conductive electronic device structures may include conductive housing structures. The housing structures may include a peripheral conductive member that runs around the periphery of an electronic device. The peripheral conductive member may serve as a bezel for a planar structure such as a display and/or may form vertical sidewalls for the device. 
     The antenna structures may be configured to handle both near field communications (e.g., communications in a near field communications band such as a 13.56 MHz band) and non-near-field communications (sometimes referred to as far field communications) such as cellular telephone communications, wireless local area network communications, and satellite navigation system communications. Near field communications typically involve communication distances of less than about 20 cm. Far field communications typically involved communication distances of multiple meters or miles. 
     Signal combining circuitry such as a duplexer or switching circuitry may be used to allow a near field communications transceiver and non-near-field-communications transceiver circuitry to share the antenna structures. By reducing or eliminating the need for separate near field communications antenna structures to handle near field communications signals, antenna structures that are shared between near field communication and non-near-field-communications circuitry can help minimize device size. 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a cellular telephone, or a media player. Device  10  may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, a television, a computer monitor, or other suitable electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may, for example, be a touch screen that incorporates capacitive touch electrodes. Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. A display cover layer such as a cover glass layer or a layer of clear plastic may cover the surface of display  14 . Buttons such as button  19  may pass through openings in the display cover layer or other outer layer in display  14 . The cover glass may also have other openings such as an opening for speaker port  26 . 
     Housing  12  may include a peripheral member such as member  16 . Member  16  may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape, member  16  may have a rectangular ring shape (as an example). Member  16  or part of member  16  may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or helps hold display  14  to device  10 ). Member  16  may also, if desired, form sidewall structures for device  10  (e.g., by forming a band with vertical sidewalls, by forming a band with rounded sidewalls, etc.). 
     Member  16  may be formed of a conductive material and may therefore sometimes be referred to as a peripheral conductive member or conductive housing structures. Member  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, three, or more than three separate structures may be used in forming member  16 . 
     It is not necessary for member  16  to have a uniform cross-section. For example, the top portion of member  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. If desired, the bottom portion of member  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). In the example of  FIG. 1 , member  16  has substantially straight vertical sidewalls. This is merely illustrative. The sidewalls of member  16  may be curved or may have any other suitable shape. In some configurations (e.g., when member  16  serves as a bezel for display  14 ), member  16  may run around the lip of housing  12  (i.e., member  16  may cover only the edge of housing  12  that surrounds display  14  and not the rear edge of housing  12  of the sidewalls of housing  12 ). 
     Display  14  may include conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. Housing  12  may include internal structures such as metal frame members, a planar sheet metal housing structure (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a substantially rectangular member that is welded or otherwise connected between opposing sides of member  16 ), printed circuit boards, and other internal conductive structures. These conductive structures may be located in the center of housing  12  under display  14  (as an example). 
     In regions  22  and  20 , openings (gaps) may be formed within the conductive structures of device  10  (e.g., between peripheral conductive member  16  and opposing conductive structures such as conductive housing structures, a conductive ground plane associated with a printed circuit board, and conductive electrical components in device  10 ). These openings may be filled with air, plastic, and other dielectrics. Conductive housing structures and other conductive structures in device  10  may serve as a ground plane for the antennas in device  10 . The openings in regions  20  and  22  may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element arm from the ground plane, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . 
     In general, device  10  may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device  10  may be located at opposing first and second ends of an elongated device housing, along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of such locations. The arrangement of  FIG. 1  is merely illustrative. 
     Portions of member  16  may be provided with gap structures. For example, member  16  may be provided with one or more gaps such as gaps  18 , as shown in  FIG. 1 . The gaps may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide member  16  into one or more peripheral conductive member segments. There may be, for example, two segments of member  16  (e.g., in an arrangement with two gaps), three segments of member  16  (e.g., in an arrangement with three gaps), four segments of member  16  (e.g., in an arrangement with four gaps, etc.). The segments of peripheral conductive member  16  that are formed in this way may form parts of antennas in device  10 . 
     In a typical scenario, device  10  may have upper and lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device  10  in region  22 . A lower antenna may, for example, be formed at the lower end of device  10  in region  20 . The antennas may be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme. 
     Antennas in device  10  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting non-near-field-communications such as local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc. Device  10  may use at least part of the same antenna structures for supporting near field communications (e.g., communications at 13.56 MHz). 
     A schematic diagram of an illustrative configuration that may be used for electronic device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, near field communications protocols, etc. 
     Circuitry  28  may be configured to implement control algorithms that control the use of antennas in device  10 . For example, circuitry  28  may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data and information on which communications bands are to be used in device  10 , control which antenna structures within device  10  are being used to receive and process data and/or may adjust one or more switches, tunable elements, or other adjustable circuits in device  10  to adjust antenna performance. As an example, circuitry  28  may control which of two or more antennas is being used to receive incoming radio-frequency signals, may control which of two or more antennas is being used to transmit radio-frequency signals, may control the process of routing incoming data streams over two or more antennas in device  10  in parallel, may tune an antenna to cover a desired communications band, may perform time-division multiplexing operations to share antenna structures between near field and non-near-field communications circuitry, etc. In performing these control operations, circuitry  28  may open and close switches, may turn on and off receivers and transmitters, may adjust impedance matching circuits, may configure switches in front-end-module (FEM) radio-frequency circuits that are interposed between radio-frequency transceiver circuitry and antenna structures (e.g., filtering and switching circuits used for impedance matching and signal routing), may adjust switches, tunable circuits, and other adjustable circuit elements that are formed as part of an antenna or that are coupled to an antenna or a signal path associated with an antenna, and may otherwise control and adjust the components of device  10 . 
     Input-output circuitry  30  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device  10  by supplying commands through input-output devices  32  and may receive status information and other output from device  10  using the output resources of input-output devices  32 . 
     Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry  35  (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems. 
     Wireless local area network transceiver circuitry  36  in wireless communications circuitry  34  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. 
     Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in cellular telephone bands such as bands in frequency ranges of about 700 MHz to about 2700 MHz or bands at higher or lower frequencies. 
     Wireless communications circuitry  34  may include near field communications circuitry  42 . Near field communications circuitry  42  may handle near field communications at frequencies such as the near field communications frequency of 13.56 MHz or other near field communications frequencies of interest. 
     Circuitry  44  such as satellite navigation system receiver circuitry  35 , wireless local area network transceiver circuitry  36 , and cellular telephone transceiver circuitry  38  that does not involve near field communications may sometimes collectively be referred to as non-near-field communications circuitry or far field communications circuitry. 
     Antenna structures  40  may be shared by non-near-field communications circuitry  44  and near field communications circuitry  42 . 
     If desired, communications circuitry  34  may include circuitry for other short-range and long-range wireless links. For example, wireless communications circuitry  34  may include wireless circuitry for receiving radio and television signals, paging circuits, etc. In near field communications, wireless signals are typically conveyed over distances of less than 20 cm. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include antenna structures  40 . Antenna structures  40  may include one or more antennas. Antennas structures  40  may be formed using any suitable antenna types. For example, antenna structures  40  may include antennas with resonating elements that are formed from loop antenna structure, patch antenna structures, inverted-F antenna structures, closed and open slot antenna structures, planar inverted-F antenna structures, helical antenna structures, strip antennas, monopoles, dipoles, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link. 
     To accommodate near field communications within the potentially tight confines of device housing  12 , antenna structures  40  may be shared between non-near-field communications circuitry  44  and near field communications circuitry  42 . When, for example, it is desired to transmit and receive cellular telephone signals or other non-near-field communications, antenna structures  40  may be used by transceiver circuitry  38 . When it is desired to transmit and receive near field communications signals, antenna structures  40  may be used to near field communications circuitry  42 . 
       FIG. 3  is a schematic diagram showing how antenna structures  40  may be shared by near field communications circuitry  42  and non-near-field communications circuitry  44 . As shown in  FIG. 3 , near field communications circuitry  42  and non-near field communications circuitry  44  may be coupled to antenna structures  40  by combining circuitry  50 . Combining circuitry  50  may include circuitry such as duplexer circuitry or switching circuitry. Combining circuitry  50  routes transmitted near field communications signals from near field communications circuitry  42  to antenna structures  40  and routes incoming near field communications signals received by antenna structures to near field communications circuitry  42 . Combining circuitry  50  also routes non-near-field communications signals that are transmitted by circuitry  44  to antenna structures  40  and routes received non-near-field communications signals from antenna structures  40  to non-near-field communications circuitry  44 . Matching circuitry in combining circuitry  50  may be used in facilitating impedance matching between antenna structures  40 , circuitry  42 , circuitry  44 , and the signal paths that couple these circuits. 
     Combining circuitry  50  allows antenna structures  40  be used by both near field communications circuitry  42  and non-near-field communications circuitry  44 . In configurations for combining circuitry that are based on actively switched circuits, control circuitry  28  can make adjustments to circuitry  50  and other circuitry in real time to ensure that near field communications signals and non-near-field communications signals are routed properly. In configurations for combining circuitry  50  that are implemented using passive components (e.g., a network of one or more components such as inductors, capacitors, resistors, etc. to form a duplexer), signals can be routed between antenna structures  40  and near field communications circuitry  42  and non-near-field communications circuitry  44  based on signal frequency (e.g., by routing lower frequency signals such as signals at 13.56 MHz between antenna structures  40  and near field communications circuitry  42  and by routing higher frequency signals such as signals above 700 MHz between antenna structures  40  and non-near-field-communications transceiver circuitry  44 ). 
     Paths such as paths  54 ,  52 , and  56  may be used in routing signals between antenna structures  40  and transceiver circuitry  42  and  44 . 
     Paths such paths  54 ,  52 , and  56  may include pairs of signal lines. Each pair of signal lines may form a transmission line or part of a transmission line. Transmission lines in device  10  may be formed from coaxial cables, microstrip transmission lines or other transmission lines that are formed from metal traces on dielectric substrates (e.g., flexible printed circuit substrates formed from flexible layers of polyimide or other sheets of polymer or rigid printed circuit boards formed from fiberglass-filled epoxy), or other suitable transmission line structures. 
     As shown in the example of  FIG. 3 , path  52  may include a positive signal line such as positive signal line  52 P and a ground signal line such as ground signal line  52 N. Path  54  may include a positive signal line such as positive signal line  54 P and a ground signal line such as ground signal line  54 N. Path  56  may include a positive signal line such as positive signal line  56 P and a ground signal line such as ground signal line  56 N. Path  54  may be coupled to an antenna feed having a positive antenna feed terminal (+) and a ground antenna feed terminal (−) (i.e., path  54 P may form a positive antenna feed line) or, if desired, other antenna feed structures may be used in feeding antenna structures  40 . 
     If desired, antenna structures  40  may be provided with multiple antenna feeds and/or components that are actively tuned (e.g., switches that are controlled by control signals from control circuitry  28 ). Configuration in which antenna structures  40  are formed from passive components and have a single antenna feed are sometimes described herein as an example. 
       FIG. 4  is a diagram of illustrative antenna structures of the type that may be shared by near field communications circuitry and non-near-field communications circuitry. As shown in  FIG. 4 , combining circuitry  50  may have an antenna feed port coupled to antenna structures  40 . Combining circuitry  50  may also include a near field communications port for handling signals associated with near field communications circuitry  42  such as the port that is coupled to near field communications circuitry  42  by path  52 . Impedance matching circuitry M1 may be used to help ensure that path  52  is impedance matched (e.g., to help create a 50 ohm impedance for circuitry  50  that is matched to a 50 ohm impedance for path  52 ). Combining circuitry  50  may include a non-near-field communications port for handling signals associated with non-near-field-communications circuitry  44  such as the port that is coupled to non-near-field communications circuitry  44  by path  56 . Impedance matching circuitry M2 may be used to help ensure that path  56  is impedance matched (e.g., to help create a 50 ohm impedance for circuitry  50  that is matched to a 50 ohm impedance for path  56 . 
     Combining circuitry  50  may include switching circuitry or passive circuitry for multiplexing the near field communications signals associated with near field communications circuitry  42  and the non-near-field communications signals associated with non-near-field communications circuitry  44 . In the example of  FIG. 4 , combining circuitry  50  includes a passive circuit that performs multiplexing (and demultiplexing) operations based on the frequency of the signals. In particular, combining circuitry  50  includes duplexer  58 . 
     Duplexer  58  includes duplexing circuitry such as inductor  70  and capacitor  72 . This circuitry allows duplexer  58  to route signals between antenna structures  40  and circuits  42  and  44  based on signal frequency. For example, the inductance value for inductor  70  may be selected so that inductor  70  exhibits a low impedance (i.e., a short circuit condition) at relatively low frequencies such as the frequencies associated with near field communications circuitry  42  (e.g., 13.56 MHz). Inductor  70  therefore allows these signals to pass from near field communications circuitry  42  to antenna structures  40  during signal transmission operations and to pass from antenna structures  40  to near field communications circuitry  42  during signal reception operations. The capacitance value for capacitor  72  may be selected so that capacitor  72  exhibits a high impedance (i.e., an open circuit condition) at relatively low frequencies such as the frequencies associated with near field communications circuitry  42  (e.g., 13.56 MHz) and thereby prevents near field communications signals from passing to non-near-field communications circuitry  44  (i.e., capacitor  58  prevents near field communications signals from interfering with the operation of non-near-field communications circuitry  44 ). 
     At high frequencies such as frequencies above 700 MHz that are associated with the operation of non-near-field communications circuitry  44 , inductor  70  will exhibit a high impedance (i.e., inductor  70  will form an open circuit). This will prevent potentially interfering non-near-field communications signals associated with circuitry  44  from reaching near field communications circuitry  42 . At the relatively high frequencies associated with non-near-field communications signals for circuitry  44 , capacitor  72  will exhibit a relatively low impedance (i.e., capacitor  72  will form a short circuit), so that circuitry  44  can transmit and receive signals using antenna structures  40 . 
     Antenna structures  40  may include an antenna resonating element and an antenna ground. In the example of  FIG. 4 , antenna structures  40  include inverted-F antenna resonating element  62  and antenna ground  60 . Other antenna configurations may be used for antenna structures  40  if desired. The example of  FIG. 4  is merely illustrative. 
     Inverted-F antenna resonating element  62  may, as an example, have a main arm that is formed from a segment of peripheral conductive housing member  16  of  FIG. 1 , extending between gaps in member  16  such as gaps  18 . Ground  60  may include other portions of member  16 , internal printed circuit board structure, internal device circuitry and structures such as radio-frequency shielding cans, mounting structures, metal portions of cameras and other components, metal brackets, etc. If desired, other configurations may be used for forming antenna structures  40 . For example, antenna structures  40  may be formed using patterned metal traces on rigid and/or flexible printed circuits or from metal traces formed on plastic carriers. 
     Antenna resonating element  62  may have resonating element arm portions such as low band branch B1, which contributes to an antenna resonance in a lower portion of the 700-2700 MHz cellular telephone spectrum (or other suitable frequency), and high band branch B2, which contributes to an antenna resonance in an upper portion of the 700-2700 MHz spectrum. Antenna resonating element arms B1 and B2 may be configured to exhibit resonances that cover cellular telephone frequencies, satellite navigation system frequencies, wireless local area network frequencies, or other suitable wireless frequencies when antenna structures  40  are operating in an inverted-F antenna mode. 
     Opening  76  is located between the main resonating element arm structure formed from branches B1 and B2 and antenna ground  60 . Opening  76  may be filled with a dielectric such as air and/or dielectric such as plastic and other dielectric materials associated with the housing and components of device  10 . Short circuit path  64  spans opening  76  and forms a return path between the main resonating element arm of resonating element  62  and antenna ground  60 . Antenna feed path  54 P spans opening  76  and is coupled to node  74  in duplexer circuitry  58 . Node  74  and feed path  54 P may form an antenna feed port for combining circuitry  50 . 
     With a sharing configuration of the type shown in  FIG. 4 , near field communications circuitry  42  and non-near-field communications circuitry  44  can use antenna structures  40  separately or at the same time. When using antenna structures  40  to handle signals associated with non-near-field communications circuitry  44 , antenna resonating element arm B1 may give rise to an antenna resonance in a first (e.g., lower) communications band and antenna resonating element arm B2 may give rise to an antenna resonance in a second (e.g., higher) communications band (as an example). When using antenna structures  40  to handle near field communications signals associated with near field communications circuitry  42 , loop current signals such as loop current  66  of  FIG. 4  may be generated in antenna structures  40 . 
     Loop current signals  66  may, for example, circulate in the antenna loop formed by path  54 P, segment  80  of resonating element arm B1, short circuit path  64 , and antenna ground  60  (which is grounded to ground path  54 N in path  54 ). Loop currents  66  may be induced in antenna structures  40  when antenna structures  40  are exposed to incoming near field communications signals  84  from external equipment  82  and/or may be generated by near field communications circuitry  42 . The conductive loop of structures formed by path  54 P, segment  80  of resonating element arm B1, short circuit path  64 , and antenna ground  60  that supports loop currents  66  serves as a loop antenna for near field communications circuitry  42 . 
     External equipment such as external equipment  82  may communicate with near field communications circuitry  42  via magnetic induction. Equipment  82  may include a loop antenna such as loop antenna  86  that is controlled by control circuitry  88 . Loop antenna  86  and the loop antenna formed from antenna structures  40  are electromagnetically coupled, as indicated by near field communications signals  84  of  FIG. 4 . Device  10  may use near field communications circuitry  42  and antenna structures  40  (e.g., the near field communications loop antenna portion of antenna structures  40 ) to communicate with external near field communications equipment  82  using passive or active communications. In passive communications, device  10  may use near field communications circuitry  42  and antenna structures  40  to modulate electromagnetic signals  84  from equipment  82 . In active communications, near field communications circuitry  42  and antenna structures  40  may transmit radio-frequency electromagnetic signals  84  to external equipment  82 . 
       FIG. 5  is a diagram of device  10  in a configuration in which antenna structures  40  have been provided with a supplemental loop mode return path such as return path  64 - 2 . Return path  64 - 2 , which may sometimes be referred to as short circuit path  64 - 2 , may span gap  76  in parallel with return path  64 - 1  (sometimes referred to as short circuit path  64 - 1 ). Inductor  90  may be interposed within path  64 - 1 . Inductor  90  may be characterized by a high impedance at high frequencies (e.g., frequencies above 700 MHz) and may be characterized by a low impedance at low frequencies (e.g., frequencies below 700 MHz or below 100 MHz such as a near field communications frequency of 13.56 MHz). Capacitor  92  may be characterized by a low impedance at high frequencies (e.g., frequencies above 700 MHz) and may be characterized by a high impedance at low frequencies (e.g., frequencies below 700 MHz or below 100 MHz such as a near field communications frequency of 13.56 MHz). 
     During operation of non-near-field communications circuitry  44  at frequencies above 700 MHz, path  64 - 1  forms a short circuit that spans gap  76  and forms a return path between the main antenna resonating element arm in inverted-F antenna resonating element  62  and ground  60  (as with short circuit path  64  of  FIG. 4 ), whereas path  64 - 2  forms an open circuit. In this scenario, path  64 - 2  will not contribute significantly to the performance of antenna structures  40  and antenna structures  40  will serve as a two-arm dual band inverted-F antenna for non-near-field communications circuitry  44 . 
     During operation of near field communications circuitry  42  at frequencies below 700 MHz (e.g., at a frequency below 100 MHz such as in a near field communications band at 13.56 MHz), capacitor  92  exhibits a high impedance so that path  64 - 1  forms an open circuit and does not participate in the performance of antenna structures  40 . Inductor  90  exhibits a low impedance, so that path  64 - 2  shorts segment  80 ′ to ground  60  and forms part of a near field communications loop antenna. In this configuration, loop currents flow through the loop antenna structures formed from feed path  54 P, segment  80 ′ of the main resonating element arm of resonating element  62 , short circuit path  64 - 2 , and ground  60 , as illustrated by loop currents  66  of  FIG. 5 . 
     In the illustrative configuration of  FIG. 6 , antenna structures  40  have been provided with parallel paths  90 A and  90 B spanning gap  76 . Path  64 - 1  forms a short circuit return path between the main arm of antenna resonating element  62  and ground  60  at frequencies above 700 MHz (e.g., when using non-near-field communications circuitry  44 ). Path  64 - 1  forms an open circuit at near field communications frequencies (e.g., frequencies below 700 MHz, below 100 MHz, 13.56 MHz, etc.). 
     Paths  64 - 2 A and  64 - 2 B span opposing ends of gap  76 . If desired, inductors  90 A and  90 B may span gaps in housing band  16  such as gaps  18  of  FIG. 1 . Inductor  90 A in path  64 - 2 A and inductor  90 B in path  64 -B may exhibit low impedances at low frequencies (e.g., frequencies below 700 MHz, below 100 MHz, 13.56 MHz, etc.), so that paths  64 - 2 A and  64 - 2 B form return paths for near field communications circuitry  42 . As shown in  FIG. 6 , path  54 P, segment  80 A of the main resonating element arm, path  64 - 2 A, and ground  60  may form a first loop antenna structure within antenna structures  40  (i.e., a loop antenna in which loop currents  66 A circulate). At the same time, path  54 P, segment  80 B of the main resonating element arm, path  64 - 2 B, and ground  60  may form a second loop antenna structure within antenna structures  40  (i.e., a loop antenna in which loop currents  66 B circulate). The use of multiple antenna loops within antenna structures  40  may increase near field communications efficiency (i.e., antenna structures  40  may exhibit enhanced near field communications loop antenna efficiency compared to single-loop configurations). 
     If desired, the conductive structures in antenna structures  40  may be configured to form multiple overlapping loops (i.e., multiple turns in a multi-loop antenna), as shown in  FIG. 7 . In antenna structures  40  of  FIG. 7 , capacitor  92  is interposed in path  100  so that path  100  forms a short circuit at non-near-field communications frequencies (e.g., frequencies above 700 MHz). Inductors  90 ′ form open circuits at these frequencies, so that paths  102  are effectively removed from antenna structures  40  and do not affect antenna performance for signals associated with non-near-field communications circuitry  44 . 
     At near field communications frequencies (e.g., frequencies below 700 MHz or below 100 MHz such as frequencies in a near field communications band at 13.56 MHz), capacitor  92  may have a high impedance and path  100  may form an open circuit. Inductors  90 ′ may exhibit low impedances, so that paths  102  (in conjunction with path  54 P, segment  80 ″ of the main resonating element arm in resonating element  62 , and ground  60 ) form multiple concentric loops. The concentric loops form a near field communications loop antenna portion of antenna structures  40 . In the example of  FIG. 7 , the near field loop antenna portion of antenna structures  40  has two concentric loops. Loop antenna configurations with three or more concentric loops may be formed if desired. 
       FIG. 8  is a diagram of device  10  showing how antenna structures may be formed at opposing ends of housing  12 , as described in connection with antenna regions  20  and  22  of  FIG. 1 . As shown in  FIG. 8 , device  10  may have first antenna structures  40 A and second antenna structures  40 B. Antenna structures  40 A and  40 B may be based on inverted-F antennas, loop antennas, patch antennas, planar inverted-F antennas, or other suitable antennas. Near field communications loop antennas may be formed within antenna structures  40 A and  40 B. Splitter  106  may be used to route signals between near field communications circuitry  42  and antenna structures  40 A and  40 B. Splitter  106  may be implemented using a passive splitter circuit and/or using switching circuitry that actively switches antenna structures  40 A or antenna structures  40 B into use. 
     As described in connection with combining circuitry  50 , combining circuitry  50 A and  50 B may be used as multiplexing circuits so that non-near-field communications circuitry  44  can share antenna structures  40 A and  40 B with near field communications circuitry  42 . Switching circuitry  108  may be used to couple non-near-field communications circuitry  44  to antenna structures  40 A or antenna structures  40 B (e.g., antenna structures  40 A or  40 B may be switched into use based on signal strength criteria, proximity sensor signals, or other suitable antenna selection criteria). 
     Antenna structures  40 A and  40 B may each include structures that form a loop antenna portion for near field communications as described in connection with  FIGS. 4, 5, 6, and 7 . Combining circuitry  50 A may be used to couple near field communications circuitry  42  (via splitter  106 ) to antenna structures  40 A while coupling non-near-field communications circuitry  44  (via switching circuitry  108 ) to antenna structures  40 A. Combining circuitry  50 B may be used to couple near field communications circuitry  42  (via splitter  106 ) to antenna structures  40 B while coupling non-near-field communications circuitry  44  (via switching circuitry  108 ) to antenna structures  40 B. 
     As shown in  FIG. 9 , antenna structures  40 A and  40 B may be configured to emit and receive radio-frequency signals  112  from both the front face of device  10  (surface  114 ) and from the rear face of device  10  (surface  116 ). With this type of arrangement, device  10  may communicate with external near field communications equipment  82  ( FIG. 4 ) regardless of whether device  10  is being held in a display up orientation (as shown in  FIG. 9 ) or display down configuration. The use of splitter  42  allows a user to use a loop antenna at either end of device  10  (or both) to support near field communications. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20121119
Publication Date: 20171017
Grant Date: 20171017
Priority Date: 20121119
Inventors: OUYANG YUEHUI
SCHLUB ROBERT W.
JIN NANBO
PASCOLINI MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/314", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/314", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/314", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 49301652