PATENT DOCUMENT

Publication Number: US-9596330-B2
Application Number: US-201414490576-A
Country: US
Kind Code: B2

Title: Antenna system with receiver diversity and tunable matching circuit

Abstract:
Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. An electronic device may include a display mounted within a housing. A peripheral conductive member may run around the edges of the display and housing. Dielectric-filled gaps may divide the peripheral conductive member into individual segments. A ground plane may be formed within the housing from conductive housing structures, printed circuit boards, and other conductive elements. The ground plane and the segments of the peripheral conductive member may form antennas in upper and lower portions of the housing. The radio-frequency transceiver circuitry may implement receiver diversity using both the upper and lower antennas. The lower antenna may be used in transmitting signals. The upper antenna may be tuned using a tunable matching circuit.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having conductive structures that form an antenna ground and having peripheral conductive housing structures that run around at least some edges of the housing; 
 radio-frequency receiver circuitry; 
 an inverted-F antenna that is formed from the antenna ground and an inverted-F antenna resonating element that is separated from the antenna ground by an opening, wherein the inverted-F antenna resonating element is formed from a segment of the peripheral conductive housing structures that is located between first and second gaps in the peripheral conductive housing structures, a first antenna feed terminal is coupled to the segment, and a second antenna feed terminal is coupled to the antenna ground; and 
 an additional antenna, wherein the additional antenna is configured to transmit and receive radio-frequency signals in a plurality of cellular telephone bands, and wherein the receiver circuitry is configured to only receive radio-frequency signals in a subset of the plurality of cellular telephone bands over the inverted-F antenna. 
 
     
     
       2. The electronic device defined in  claim 1 , further comprising an antenna feed line that is coupled to the first and second antenna feed terminals and that carries antenna signals to the segment. 
     
     
       3. The electronic device defined in  claim 2 , wherein the additional antenna is formed from the antenna ground and an additional segment of the peripheral conductive housing structures. 
     
     
       4. The electronic device defined in  claim 3 , further comprising an additional antenna feed line that carries additional antenna signals to the additional segment. 
     
     
       5. The electronic device defined in  claim 4 , further comprising an impedance matching circuit interposed on the antenna feed line and an adjustable impedance matching circuit interposed on the additional antenna feed line. 
     
     
       6. The electronic device defined in  claim 1 , wherein the first and second gaps are formed at opposing ends of the segment. 
     
     
       7. The electronic device defined in  claim 6 , wherein the first and second gaps extend from an external rear surface of the electronic device to an external front surface of the electronic device. 
     
     
       8. The electronic device defined in  claim 1 , wherein the segment of the peripheral conductive housing structures comprise an external surface of the electronic device. 
     
     
       9. The electronic device defined in  claim 1 , wherein the segment of the peripheral conductive housing structures and the antenna ground surround a dielectric opening, the electronic device further comprising a conductive structure that bridges the dielectric opening and shorts the peripheral conductive housing structures to the ground. 
     
     
       10. An electronic device, comprising:
 a housing having opposing first and second ends; 
 a display mounted within the housing, wherein the display has four edges; 
 peripheral conductive housing structures that run along the four edges of the display; 
 an antenna ground that is formed at least partly from conductive portions of the housing; 
 a first antenna that is formed from an antenna resonating element and the antenna ground, wherein the antenna resonating element is formed from a first segment of the peripheral conductive housing structures and is separated from the antenna ground by an opening, a first antenna feed terminal for the first antenna is coupled to the first segment, and a second antenna feed terminal for the first antenna is coupled to the antenna ground; 
 a second antenna having an antenna resonating element that is formed from a second segment of the peripheral conductive housing structures and the antenna ground, wherein a first antenna feed terminal for the second antenna is coupled to the second segment and a second antenna feed terminal for the second antenna is coupled to the antenna ground; 
 radio-frequency transceiver circuitry that transmits and receives radio-frequency antenna signals through the second antenna in a plurality of cellular telephone communications bands and that only receives radio-frequency antenna signals through the first antenna in a subset of the cellular telephone communications bands. 
 
     
     
       11. The electronic device defined in  claim 10 , wherein the radio-frequency transceiver circuitry is configured to receive the radio-frequency antenna signals in at least five cellular telephone receive bands via the second antenna, is configured to transmit the radio-frequency antenna signals in at least five cellular telephone transmit bands via the second antenna, and is configured to receive the radio-frequency antenna signals in no more than four of the five cellular telephone receive bands via the first antenna. 
     
     
       12. The electronic device defined in  claim 11  further comprising a tunable matching circuit coupled between the radio-frequency transceiver circuitry and the first antenna, wherein the tunable matching circuit is operable in a first mode in which the radio-frequency antenna signals are received by the first antenna in only first and second cellular telephone receive bands among the five cellular telephone receive bands and is operable in a second mode in which the radio-frequency antenna signals are received by the first antenna in only third and fourth cellular telephone receive bands among the five cellular telephone receive bands and wherein the first and second cellular telephone receive bands are different than the third and fourth cellular telephone receive bands. 
     
     
       13. The electronic device defined in  claim 10  wherein the first end of the electronic device comprises a lower end of the electronic device, the second end of the electronic device comprises an upper end of the electronic device, and the peripheral conductive housing structures comprise at least three gaps that define at least three separate segments of the peripheral conductive member including the first and second segments, the at least three gaps each extending from a planar rear exterior surface of the electronic device to a planar front exterior surface of the electronic device. 
     
     
       14. The electronic device defined in  claim 10  wherein the radio-frequency transceiver circuitry is configured to receive signals through the second antenna and the first antenna and wherein the radio-frequency transceiver circuitry is configured to transmit signals through only the second antenna and not the first antenna, so that the electronic device supports receiver diversity and not transmitter diversity. 
     
     
       15. An electronic device, comprising:
 a housing having opposing upper and lower ends; 
 a display mounted within the housing, wherein the display has four edges; 
 peripheral conductive housing structures that run along the four edges of the display; 
 at least two dielectric-filled gaps in the peripheral conductive housing structures that separate the peripheral conductive member into at least first and second respective segments; 
 an antenna ground plane within the housing; 
 a dual-arm inverted-F antenna that is formed from the antenna ground plane and an inverted-F antenna resonating element that is separated from the antenna ground plane by an opening and that has first and second arms that resonate in respective frequency bands, wherein the inverted-F antenna resonating element is formed from the first segment, a first antenna feed terminal is coupled to the first segment, and a second antenna feed terminal is coupled to the antenna ground plane at the upper end of the housing; 
 a loop antenna having a resonating element that is formed from the second segment and the antenna ground plane at the lower end of the housing, wherein the resonating element of the loop antenna extends between a third antenna feed terminal coupled to the antenna ground plane and a fourth antenna feed terminal coupled to the second segment; and 
 radio-frequency transceiver circuitry that is configured to transmit and receive radio-frequency antenna signals in a plurality of radio-frequency bands through the loop antenna and that is configured to receive radio-frequency antenna signals in only a subset of the plurality of radio-frequency bands through the dual-arm inverted-F antenna without transmitting any radio-frequency signals through the dual-arm inverted-F antenna. 
 
     
     
       16. The electronic device defined in  claim 15 , wherein the dual-arm inverted-F antenna comprises first and second portions extending from opposing sides of the first feed terminal in a common plane, wherein the first and second portions are configured to cover the respective frequency bands, and wherein the first and second portions each have a respective perpendicular bend. 
     
     
       17. The electronic device defined in  claim 15 , further comprising:
 a fixed matching circuit coupled between the radio-frequency transceiver circuit and the loop antenna; and 
 an adjustable matching circuit coupled between the radio-frequency transceiver circuit and the dual-arm inverted-F antenna. 
 
     
     
       18. The electronic device defined in  claim 17 , further comprising:
 a power amplifier coupled between a transmitter circuit in the radio-frequency transceiver circuit and the fixed matching circuit; and 
 a low noise amplifier coupled between a receiver circuit in the radio-frequency transceiver circuit and the fixed matching circuit. 
 
     
     
       19. The electronic device defined in  claim 18 , further comprising:
 a satellite navigation system receiver circuit that is separate from the radio-frequency transceiver circuit and that is coupled to the adjustable matching circuit; and 
 filtering circuitry coupled between the satellite navigation system receiver circuit and the adjustable matching circuit. 
 
     
     
       20. The electronic device defined in  claim 19 , further comprising:
 an additional low noise amplifier coupled between the filtering circuitry and an additional receiver circuit in the radio-frequency transceiver circuit; and 
 control circuitry, wherein the control circuitry is configured to provide control signals to the radio-frequency transceiver circuit over a first control path to selectively activate the receiver circuit and the additional receiver circuit, and wherein the control circuitry is configured to provide additional control signals over an additional control path to the adjustable matching circuit to tune the dual-arm inverted-F antenna.

Description:
This application is a continuation of U.S. patent application Ser. No. 12/941,010, filed Nov. 5, 2010. This application claims the benefit of and claims priority to U.S. patent application Ser. No. 12/941,010, filed Nov. 5, 2010, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to wireless communications circuitry, and more particularly, to electronic devices that have 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 at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz. Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. For example, electronic devices may communicate using the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz. 
     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, it may be desirable to include conductive structures in an electronic device such as metal device housing components. Because conductive components can affect radio-frequency performance, care must be taken when incorporating antennas into an electronic device that includes conductive structures. Moreover, care must be taken to ensure that the antennas and wireless circuitry in a device are able to operate satisfactorily even in areas of weak radio-frequency signal strength. 
     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. An electronic device may include a display mounted within a housing. A peripheral conductive member may run around the edges of the display and housing. 
     The peripheral conductive member may be divided into individual segments by forming gaps in the peripheral conductive member at various points along its length. The gaps may be filled with a dielectric such as plastic and may form an open circuit between opposing portions of the conductive member. With one illustrative configuration, three gaps may be formed in the peripheral conductive member to divide the peripheral conductive member into three respective segments. 
     A conductive housing member such as a conductive midplate member that spans the width of the housing may be connected to the peripheral conductive member at the left and right edges of the display. The conductive housing member and other conductive structures such as electrical components and printed circuits may form a ground plane. The ground plane and the peripheral conductive member segments may surround dielectric openings to form the antenna structures. For example, an upper cellular telephone antenna may be formed at an upper end of the housing and a lower cellular telephone antenna may be formed at a lower end of the housing. In the upper cellular telephone antenna, a first dielectric opening may be surrounded by at least some of a first peripheral conductive member segment and portions of the ground plane. In the lower cellular telephone antenna, a second dielectric opening may be surrounded by at least some of a second peripheral conductive member segment and portions of the ground plane. The upper cellular telephone antenna may be a two-branch inverted-F antenna. The lower cellular telephone antenna may be a loop antenna. 
     The radio-frequency transceiver circuitry may be coupled to the upper and lower antennas using matching circuits. A fixed matching circuit may be used to couple the radio-frequency transceiver circuitry to the lower antenna. A fixed matching circuit or a tunable matching circuit may be used to couple the radio-frequency transceiver circuitry to the upper antenna. 
     During operation of the electronic device, the lower antenna may serve as the primary cellular antenna for the device. Radio-frequency antenna signals may be transmitted and received by the lower antenna in cellular telephone bands such as the bands at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz. The upper antenna may serve as a secondary antenna that allows the electronic device to implement receiver diversity. When the performance of the lower antenna drops during operation, the radio-frequency transceiver circuitry in the device can receive signals with the upper antenna rather than the lower antenna. 
     The upper antenna may support only a subset of the bands that are supported by the lower antenna. For example, the upper antenna may support only two receive sub-bands. If desired, the coverage of the upper antenna can be extended by tuning the matching circuit for the upper antenna in real time. This arrangement may allow the upper antenna to cover first and second receive bands during a first mode of operation and third and fourth receive bands during a second mode of operation. 
     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 cross-sectional end view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 4  is a diagram of illustrative wireless circuitry including multiple antennas in accordance with an embodiment of the present invention. 
         FIG. 5  is a circuit diagram of an illustrative tunable matching circuit of the type that may be used in connection with the wireless circuitry of  FIG. 4  in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of an electronic device of the type shown in  FIG. 1  showing how antennas may be formed within the device in accordance with an embodiment of the present invention. 
         FIG. 7  is a chart showing how antennas of the type shown in  FIG. 6  may be used in covering communications bands of interest by tuning a matching filter of the type shown in  FIG. 5  in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram of an antenna of the type shown in the upper portion of the device of  FIG. 6  in accordance with an embodiment of the present invention. 
         FIG. 9  is a graph showing how an antenna of the type shown in  FIG. 8  may exhibit high band and low band resonance peaks in accordance with an embodiment of the present invention. 
         FIG. 10  is a diagram highlighting a high band portion of the antenna diagram of  FIG. 8 . 
         FIG. 11  is a graph showing how the high band antenna structures of  FIG. 10  may resonant at communications frequencies associated with a high band and, with the inclusion of matching circuitry, in a Global Positioning System (GPS) band in accordance with an embodiment of the present invention. 
         FIG. 12  is a diagram highlighting a low band portion of the antenna diagram of  FIG. 8 . 
         FIG. 13  is a graph showing how the low band antenna structures of  FIG. 12  may resonant at communications frequencies associated with a low band in accordance with an embodiment of the present invention. 
         FIG. 14  is a graph showing how the high band and low band portions of the antenna of  FIG. 8  may be used to cover multiple communications bands of interest using a tunable matching circuit in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices 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 one or more antennas. 
     The antennas can 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. Conductive structures for the antennas 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, may serve as sidewall structures for a device housing, or may form other housing structures. Gaps in the peripheral conductive member may be associated with the antennas. 
     An illustrative electronic device of the type that may be provided with one or more antennas is shown in  FIG. 1 . 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, a media player, etc. 
     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 form light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electronic ink elements, liquid crystal display (LCD) components, or other suitable image pixel structures. A cover glass layer may cover the surface of display  14 . Buttons such as button  19  may pass through openings in the cover glass. 
     Housing  12  may include structures such as peripheral member  16 . Member  16  may run around the rectangular periphery of device  10  and display  14 . 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 . 
     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, or more than two separate structures may be used in forming member  16 . In a typical configuration, member  16  may have a thickness (dimension TT) of about 0.1 mm to 3 mm (as an example). The sidewall portions of member  16  may, as an example, be substantially vertical (parallel to vertical axis V). Parallel to axis V, member  16  may have a dimension TZ of about 1 mm to 2 cm (as an example). The aspect ratio R of member  16  (i.e., the ratio R of TZ to TT) is typically more than 1 (i.e., R may be greater than or equal to 1, greater than or equal to 2, greater than or equal to 4, greater than or equal to 10, etc.). 
     It is not necessary for member  16  to have a uniform cross-section. For example, the top portion of member  16  may, if desired, nave 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  also include internal structures such as metal frame members, a planar housing member (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 center CN of housing  12  (as an example). 
     In regions  22  and  20 , openings may be formed between the conductive housing structures and conductive electrical components that make up device  10 . These openings may be filled with air, plastic, or other dielectrics. Conductive housing structures and other conductive structures in region CN of 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 from the ground plane, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . 
     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 A,  18 B,  18 C, and  18 D, as shown in  FIG. 1 . The gaps may be filled with dielectric such as polymer, ceramic, glass, etc. Gaps  18 A,  18 B,  18 C, and  18 D 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 separate communications bands of interest or may be used together 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 local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc. 
     A schematic diagram of electronic device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include 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 . This 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, etc. 
     Circuitry  28  may be configured to implement control algorithms that control the use of antennas in device  10 . For example, to support antenna diversity schemes and MIMO schemes or other multi-antenna schemes, circuitry  28  may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data, control which antenna structures within device  10  are being used to receive and process data. 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, 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), 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). Transceiver circuitry  36  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 at 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz or other cellular telephone bands of interest. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment, wireless circuitry for receiving radio and television signals, paging circuits, etc. 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 antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  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. 
     A cross-sectional side view of device  10  of  FIG. 1  taken along line  24 - 24  in  FIG. 1  and viewed in direction  26  is shown in  FIG. 3 . As shown in  FIG. 3 , display  14  may be mounted to the front surface of device  10 . Housing  12  may include sidewalls formed from member  16  and one or more rear walls formed from structures such as planar rear housing structure  42 . Structure  42  may be formed from a dielectric such as glass, ceramic, or plastic, and/or metals or other suitable materials (e.g., fiber composites). Snaps, clips, screws, adhesive, and other structures may be used in assembling the parts of housing  12  together. 
     Device  10  may contain printed circuit boards such as printed circuit board  46 . Printed circuit board  46  and the other printed circuit boards in device  10  may be formed from rigid printed circuit board material (e.g., fiberglass-filled epoxy) or flexible sheets of material such as polymers. Flexible printed circuit boards (“flex circuits”) may, for example, be formed from flexible sheets of polyimide. 
     Printed circuit board  46  may contain interconnects such as interconnects  48 . Interconnects  48  may be formed from conductive traces (e.g., traces of gold-plated copper or other metals). Connectors such as connector  50  may be connected to interconnects  48  using solder or conductive adhesive (as examples). Integrated circuits, discrete components such as resistors, capacitors, and inductors, and other electronic components may be mounted to printed circuit board  46 . 
     Antennas in device  10  such as illustrative antenna  40  of  FIG. 3  may have antenna feed terminals. For example, each antenna in device  10  may have a positive antenna feed terminal such as positive antenna feed terminal  58  and a ground antenna feed terminal such as ground antenna feed terminal  54 . As shown in the illustrative arrangement of  FIG. 3 , a transmission line path such as coaxial cable  52  may be coupled between the antenna feed formed from terminals  58  and  54  and transceiver circuitry in components  44  via connector  50  and interconnects  48 . Components  44  may include one or more integrated circuits for implementing wireless circuitry  34  of  FIG. 2  (e.g., receiver  35  and transceiver circuits  36  and  38 ). 
     Connectors such as connector  50  may be used in coupling transmission lines in device  10  to printed circuit boards such as board  46 . Connector  50  may be, for example, a coaxial cable connector that is connected to printed circuit board  46  using solder (as an example). Cable  52  may be a coaxial cable or other transmission line. Examples of transmission lines that may be used in device  10  include coaxial cables, microstrip and stripline transmission lines formed from a flex circuit or rigid printed circuit board, transmission lines that are formed from multiple transmission line structures such as these, etc. 
     When coupled to the feed of antenna  40 , transmission line  52  may be used to transmit and receive radio-frequency signals using antenna  40 . As shown in  FIG. 3 , terminal  58  may be coupled to coaxial cable center connector  56 . Terminal  54  may be connected to a ground conductor in cable  52  (e.g., a conductive outer braid conductor). Other arrangements may be used for coupling transceivers in device  10  to antenna  40  if desired. For example, impedance matching circuits may be used in coupling transceiver circuitry to antenna structures. The arrangement of  FIG. 3  is merely illustrative. 
     In the illustrative example of  FIG. 3 , device  10  includes antenna  40 . To enhance signal quality and to cover multiple bands of interest, device  10  may contain multiple antennas. With one suitable arrangement, which is sometimes described herein as an example, a WiFi® antenna may be located in region  22 , a first (e.g., a primary) cellular telephone antenna may be located in region  20 , and a second (e.g., secondary) cellular telephone antenna may be located in region  22 . The second cellular telephone antenna may, if desired, be configured to receive GPS signals. Illustrative wireless circuitry  34  that includes an antenna arrangement of this type is shown in  FIG. 4 . 
     As shown in  FIG. 4 , wireless circuitry  34  may have input-output ports such as ports  100  and  130  for interfacing with digital data circuits in storage and processing circuitry  28 . Wireless circuitry  34  may include one or more integrated circuits for implementing transceiver circuits such as baseband processor  102  and cellular telephone transceiver circuitry  38 . Port  100  may receive digital data from storage and processing circuitry  28  for transmission over antenna  40 L. Incoming data that has been received by antennas  40 U and  40 L, cellular transceiver circuitry  38 , and baseband processor  102  may be supplied to storage and processing circuitry  28  via port  100 . Port  130  may be used to handle digital data associated with transmitted and received wireless local area network signals such as WiFi® signals (as an example). Outgoing digital data that is supplied to port  130  by storage and processing circuitry  28  may be transmitted using wireless local area network transceiver circuitry  36 , paths such as path  128 , and one or more antennas such as antenna  40 WF. During data reception operations, signals received by antenna  40 WF may be provided to transceiver  36  via path  128 . Transceiver  36  may convert the incoming signals to digital data. The digital data may be provided to storage and processing circuitry  28  via port  130 . If desired, local signals such as Bluetooth® signals may also be transmitted and received via antennas such as antenna  40 WF. 
     Transceiver circuitry  38  may include one or more transmitters and one or more receivers. In the example of  FIG. 4 , transceiver circuitry  38  includes radio-frequency transmitter  104  and radio-frequency receivers  110 . Transmitter  104  and receivers  110  (i.e., receiver RX 1  and receiver RX 2 ) may be used to handle cellular telephone communications. Signals that are received by transmitter  104  over path  118  may be supplied to power amplifier  106  by transmitter  104 . Power amplifier  106  may strengthen these outgoing signals for transmission over antenna  40 L. Incoming signals that are received by antenna  40 L may be amplified by low noise amplifier  112  and provided to receiver RX 1 . Receiver RX 1  may provide data received from antenna  40 U to processor  102  via path  118 . Incoming signals that are received by antenna  40 U may be amplified by low noise amplifier  124  and provided to receiver RX 2  (or to RX 1  using a switch). Receiver RX 2  may provide data received from antenna  40 L to processor  102  via path  118 . Circuits such as transmitter  104  and receivers  110  may each have multiple ports (e.g., for handling different respective communications bands) and may be implemented using one or more individual integrated circuits. 
     Antennas  40 U and  40 L may be coupled to transceiver circuitry  38  using circuitry such as impedance matching circuitry, filters, and switches. This circuitry, which is sometimes referred to as front-end module (FEM) circuitry, can be controlled by storage and processing circuitry in device  10  (e.g., control signals from a processor such as baseband processor  102 ). As shown in the example of  FIG. 4 , the front-end circuitry in wireless circuitry  34  may include impedance matching circuitry  108  such as matching circuit M 1  and matching circuit M 2 . Impedance matching circuitry  108  may be formed using conductive structures with associated capacitance, resistance, and inductance values, and/or discrete components such as inductors, capacitors, and resistors that form circuits to match the impedances of transceiver circuitry  38  and antennas  40 U and  40 L. Matching circuit M 1  may be coupled between wireless transceiver circuitry  38  (including associated amplifier circuitry  106  and  112 ) and antenna  40 L. Matching circuit M 2  may be coupled between transceiver circuitry  38  (and associated amplifier  124 ) and antenna  40 U using paths such as paths  132  and  122 . 
     Matching circuits M 1  and M 2  may be fixed or adjustable. For example, matching circuit M 1  may be fixed and matching circuit M 2  may be adjustable. In this type of configuration, a control circuit such as baseband processor  102  may issue control signals such as signal SELECT on path  116  of wireless circuitry  34 . Signal SELECT may be distributed to matching circuit M 2 . When SELECT has a first value, matching circuit M 2  may be placed in a first configuration. When SELECT has a second value, matching circuit M 2  may be placed in a second configuration. The state of matching circuit M 2  may serve to tune antenna  40 U so that different communications bands are covered by antenna  40 U. By using an antenna tuning scheme of this type, antenna  40 U may be able to cover a wider range of communications frequencies than would otherwise be possible. The use of tuning for antenna  40 U may allow a relatively narrow bandwidth (and potentially compact) design to be used for antenna  40 U, if desired. 
     Control signals may be provided to receiver circuitry  110  over path  119  so that wireless circuitry  34  can selectively activate one or both of receivers RX 1  and RX 2  or can otherwise select which antenna signals are being received in real time (e.g., by controlling a multiplexer in circuitry  34  that routes signals from a selected one of the antennas to a shared receiver so that the receiver can be shared between antennas). For example, baseband processor  102  or other storage and processing circuitry in device  10  can monitor signal quality (bit error rate, signal-to-noise ratio, frame error rate, signal power, etc.) for signals being received by antennas  40 U and  40 L. Based on real-time signal quality information or other data (e.g., sensor data indicating that a particular antenna is blocked), signals on path  119  or other suitable control signals can be adjusted so that optimum receiver circuitry (e.g., receiver RX 1  or RX 2 ) is used to receive the incoming signals. Antenna diversity schemes such as this in which circuitry  34  selects an optimum antenna and receiver no use in real time based on signal quality measurements or other information while transmitted signals are transmitted by a fixed antenna and transmitter (i.e., antenna  40 L and transmitter  104 ) may sometimes be referred to as receiver diversity schemes. 
     In a receiver diversity configuration (i.e., in a device without transmitter diversity), the radio-frequency transmitter circuitry in a device is configured to receive signals through two or more different antennas, so that an optimum antenna can be chosen in real time to enhance signal reception, whereas the radio-frequency transceiver circuitry is configured to transmit signals through only a single one of the antennas and not others. If desired, wireless circuitry  34  may be configured to implement both receiver and transmitter diversity and/or may be configured to handle multiple simultaneous data streams (e.g., using a MIMO arrangement). The use of wireless circuitry  34  to implement a receiver diversity scheme while using a dedicated antenna for handling transmitted signals is merely illustrative. 
     As shown in  FIG. 4 , wireless circuitry  34  may be provided with filter circuitry such as filter circuitry  126 . Circuitry  126  may route signals by frequency, so that cellular telephone signals are conveyed between antenna  40 U and receiver RX 2 , whereas GPS signals that are received by antenna  40 U are routed to GPS receiver  35 . 
     Illustrative tunable circuitry that may be used for implementing matching circuit M 2  of  FIG. 4  is shown in  FIG. 5 . As shown in  FIG. 5 , matching circuit M 2  may have switches such as switches  134  and  136 . Switches  134  and  136  may have multiple positions (shown by the illustrative A and B positions in  FIG. 5 ). When signal SELECT has a first value, switches  134  and  136  may be put in their A positions and matching circuit MA may be switched into use. When signal SELECT has a second value, switches  134  and  136  may be placed in their B positions (as shown in  FIG. 5 ), so that matching circuit MB is connected between paths  132  and  122 . 
       FIG. 6  is a top view of the interior of device  10  showing how antennas  40 L,  40 U, and  40 WF may be implemented within housing  12 . As shown in  FIG. 6 , ground plane G may be formed within housing  12 . Ground plane G may form antenna ground for antennas  40 L,  40 U, and  40 WF. Because ground plane G may serve as antenna ground, ground plane G may sometimes be referred to as antenna ground, ground, or a ground plane element (as examples). 
     In central portion C of device  10 , ground plane G may be formed by conductive structures such as a conductive housing midplate member that is connected between the left and right edges of member  16 , printed circuit boards with conductive ground traces, etc. At ends  22  and  20  of device  10 , the shape of ground plane G may be determined by the shapes and locations of conductive structures that are tied to ground. Examples of conductive structures that may overlap to form ground plane G include housing structures (e.g., a conductive housing midplate structure, which may have protruding portions), conductive components (e.g., switches, cameras, data connectors, printed circuits such as flex circuits and rigid printed circuit boards, radio-frequency shielding cans, buttons such as button  144  and conductive button mounting structure  146 ), and other conductive structures in device  10 . In the illustrative layout of  FIG. 6 , the portions of device  10  that are conductive and tied to ground to form part of ground plane G are shaded and are contiguous with central portion C. 
     Openings such as openings  138  and  146  may be formed between ground plane G and respective portions of peripheral conductive member  16 . Openings  138  and  146  may be filled with air, plastic, and other dielectrics. Openings  138  and  146  may be associated with antenna structures  40 . 
     Lower antenna  40 L may be formed by a loop antenna structure having a shape that is determined at least partly by the shape of the lower portions of ground plane G and conductive housing member  16 . In the example of  FIG. 6 , opening  138  is depicted as being rectangular, but this is merely illustrative. In practice, the shape of opening  138  may be dictated by the placement of conductive structures in region  20  such as a microphone, flex circuit traces, a data port connector, buttons, a speaker, etc. 
     Lower antenna  40 L may be fed using an antenna feed made up of positive antenna feed terminal  58 - 1  and ground antenna feed terminal  54 - 1 . Transmission line  52 - 1  (see, e.g., path  122  of  FIG. 4 ) may be coupled to the antenna feed for lower antenna  40 L. Gap  18 B may form a capacitance that helps configure the frequency response of antenna  40 L. If desired, device  10  may have conductive housing portions, matching circuit elements, and other structures and components that help match the impedance of transmission line  52 - 1  to antenna  40 L (see, e.g., illustrative matching circuit M 1  of  FIG. 4 ). 
     Antenna  40 WF may have an antenna resonating element formed from a strip of conductor such as strip  142 . Strip  142  may be formed from a trace on a flex circuit, from a trace on a rigid printed circuit board, from a strip of metal foil, or from other conductive structures. Antenna  40 WF may be fed by transmission line  52 - 2  (see, e.g., path  128  of  FIG. 4 ) using antenna feed terminals  58 - 2  and  54 - 2 . 
     Antenna  40 U may be a two-branch inverted-F antenna. Transmission line  52 - 3  (see, e.g., path  120  of  FIG. 4 ) may be used to feed antenna  40 U at antenna feed terminals  58 - 3  and  54 - 3 . Conductive structure  150  may be bridge dielectric opening  140  and may be used to electrically short ground plane G to peripheral housing member  16 . Conductive structure  148  and matching circuit M 2  may be used to connect antenna feed terminal  58 - 3  to peripheral conductive member  16  at point  152 . Conductive structures such as structures  148  and  150  may be formed by flex circuit traces, conductive housing structures, springs, screws, or other conductive structures. 
     Gaps such as gaps  18 B,  18 C, and  18 D may be present in peripheral conductive member  16 . (Gap  18 A of  FIG. 1  may be absent or may be implemented using a phantom gap structure that cosmetically looks like a gap from the exterior of device  10 , but that is electrically shorted within the interior of housing  12  so that no gap is electrically present in the location of gap  18 A.) The presence of gaps  18 B,  18 C, and  18 D may divide peripheral conductive member  16  into segments. As shown in  FIG. 6 , peripheral conductive member  16  may include first segment  16 - 1 , second segment  16 - 2 , and third segment  16 - 3 . 
     Segment  16 - 1  may form antenna resonating element arms for antenna  40 U. In particular, a first portion (segment) of segment  16 - 1  (having arm length LBA) may extend from point  152  (where segment  16 - 1  is fed) to the end of segment  16 - 1  that is defined by gap  18 C and a second portion (segment) of segment  16 - 1  (having arm length HBA) may extend from point  152  to the opposing end of segment  16 - 1  that is defined by gap  18 D. The first and second portions of segment  16 - 1  may form respective branches of an inverted F antenna and may be associated with respective low band (LB) and high band (HB) antenna resonances for antenna  40 U. 
     Antenna  40 L may cover the transmit and receive sub-bands in five communications bands (e.g., 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz), as shown in the table of  FIG. 7 . Antenna  40 U may be configured to cover a subset of these five illustrative communications bands. For example, antenna  40 U may be configured to cover a two receive bands of interest and, with tuning, four receive bands of interest. 
     In arrangements in which matching circuit M 2  is fixed, for example, antenna  40 U may be configured to cover receive bands 850 RX (the 850 MHz receive band) and 1900 RX (the 1900 MHz receive band), may be configured to cover receive bands 900 RX (the 900 MHz receive band) and 2100 RX (the 2100 MHz receive band), or may be configured to cover any other suitable pair or set of these bands. 
     In arrangements in which matching circuit M 2  is adjustable, antenna  40 U may be tuned to cover all four of these receive bands. In particular, M 2  can be placed in state MA to configure antenna  40 U to cover the 850 RX and 1900 RX communications bands and can be placed in state MB to configure antenna  40 U to cover the 900 RX and 2100 RX communications bands. 
       FIG. 8  is a circuit diagram of antenna  40 U. As shown in  FIG. 8 , gaps  18 C and  18 D may be associated with respective capacitances C 2  and C 1 . Ground plane G may form antenna ground. Short circuit branch  150  may form a stub that connects peripheral conductive member segment  15 - 1  to ground G to facilitate impedance matching between the antenna feed (formed form feed terminals  58 - 3  and  54 - 3 ) and antenna  40 U. 
     The graph of  FIG. 9  characterizes the performance of antenna  40 U by plotting standing wave ratio (SWF) values as a function of antenna operating frequency f. As shown in  FIG. 9 , there may be two resonances associated with antenna  40 U of  FIG. 8 —low band LB and high band HB. The values of the frequency ranges covered by bands LB and HB depend on the configuration of antenna  40 U. With one suitable arrangement, band LB corresponds to a band such as the 850 RX band or the 900 RX band (as examples) and band HB corresponds to a band such as the 1900 RX or 2100 RX band (as examples). 
       FIG. 10  shows the portion of antenna  40 U that contributes to antenna coverage in band HB (where inactive portions of the antenna are depicted using dashed lines).  FIG. 11  includes an illustrative SWR plot for the portion of antenna  40 U that is shown in  FIG. 10 . The solid line in  FIG. 11  corresponds to the performance of the  FIG. 10  circuitry in the absence of matching circuit M 2 . The dashed line in  FIG. 11  shows how a GPS resonance (e.g., at 1575 MHz) may be associated with the response of antenna  40 U when matching circuit M 2  is present. The frequency range of band HB may coincide with band 1900 RX or band 2100 RX, as described in connection with  FIG. 7 . 
       FIG. 12  shows the portion of antenna  40 U that contributes to antenna coverage in band LB (where inactive portions of the antenna are depicted using dashed lines).  FIG. 13  includes an illustrative SWR plot for the portion of antenna  40 U that is shown in  FIG. 12 . The frequency range of band LB may coincide with band 850 RX or band 900 RX, as described in connection with  FIG. 7 . 
       FIG. 14  includes an illustrative SWR plot for antenna  40 U of  FIG. 8  (e.g., antenna  40 U of  FIG. 6 ). The solid line in  FIG. 14  corresponds to the response of antenna  40 U when matching circuit M 2  is in its “MA” configuration. In the MA configuration, antenna  40 U can cover receive bands 850 RX and 1900 RX and the GPS band at 1575 MHz. When signal SELECT is adjusted to place matching circuit M 2  in its “MB” configuration, antenna  40 U may be characterized by the dashed line of  FIG. 14 . In the MB configuration, antenna  40 U can cover receive bands 900 RX and 1900 RX while still covering the GPS band at 1575 MHz (i.e., because the frequency response of antenna  40 U is not shifted substantially in the vicinity of 1575 MHz as a function of the state of matching circuit M 2 ). 
     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: 20140918
Publication Date: 20170314
Grant Date: 20170314
Priority Date: 20101105
Inventors: CABALLERO RUBEN
PASCOLINI MATTIA
NARANG MOHIT
MOW MATTHEW A.
SCHLUB ROBERT W.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 46019130