PATENT DOCUMENT

Publication Number: US-9559433-B2
Application Number: US-201313846481-A
Country: US
Kind Code: B2

Title: Antenna system having two antennas and three ports

Abstract:
Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may form a dual arm inverted-F antenna and a monopole antenna sharing a common antenna ground. The antenna structures may have three ports. A first antenna port may be coupled to an inverted-F antenna resonating element at a first location and a second antenna port may be coupled to the inverted-F antenna resonating element at a second location. A third antenna port may be coupled to the monopole antenna. Tunable circuitry can be used to tune the antenna structures. An adjustable capacitor may be coupled to the first port to tune the inverted-F antenna. An additional adjustable capacitor may be coupled to the third port to tune the monopole antenna. Transceiver circuitry for supporting wireless local area network communications, satellite navigation system communications, and cellular communications may be coupled to the first, second, and third antenna ports.

Claims:
What is claimed is: 
     
       1. Electronic device antenna structures, comprising:
 an antenna ground; 
 a first antenna resonating element that forms a first antenna with the antenna ground, wherein the first antenna has first and second ports; 
 a second antenna resonating element that forms a second antenna with the antenna ground that is separate from the first antenna and that has a third port; 
 radio-frequency transceiver circuitry that receives radio-frequency signals in a first frequency band over the first port and that receives radio frequency signals in a second frequency band that is different from the first frequency band over the third port; and 
 band pass filter circuitry coupled to the second port, wherein the band pass filter circuitry is configured to pass satellite navigation signals in a satellite navigation frequency band from the second port to the radio-frequency transceiver circuitry and the first and second frequency bands are different from the satellite navigation frequency band. 
 
     
     
       2. The electronic device antenna structures defined in  claim 1  wherein the first antenna resonating element comprises an inverted-F antenna resonating element. 
     
     
       3. The electronic device antenna structures defined in  claim 2  further comprising an adjustable capacitor coupled to the first port, wherein the adjustable capacitor is configured to tune the first antenna. 
     
     
       4. The electronic device antenna structures defined in  claim 1  wherein the first antenna resonating element comprises a portion of a peripheral conductive housing structure. 
     
     
       5. The electronic device antenna structures defined in  claim 4  wherein the portion of the peripheral conductive housing structure is configured to form a dual arm inverted-F antenna resonating element. 
     
     
       6. The electronic device antenna structures defined in  claim 5  wherein the second antenna resonating element comprises a monopole antenna resonating element. 
     
     
       7. The electronic device antenna structures defined in  claim 6  further comprising an adjustable capacitor that is configured to tune the second antenna. 
     
     
       8. An electronic device, comprising:
 antenna structures having first, second, and third antenna ports, wherein the antenna structures include an antenna ground, an inverted-F antenna resonating element that forms an inverted-F antenna with the antenna ground, and a monopole antenna resonating element that forms a monopole antenna with the antenna ground, the first and second antenna ports are coupled to different locations on the inverted-F antenna resonating element, and the third antenna port is coupled to the monopole antenna resonating element; 
 a duplexer; 
 a first wireless transceiver that transmits radio-frequency signals to the third antenna port through the duplexer; and 
 a second wireless transceiver that transmits radio-frequency signals to the third antenna port through the duplexer and to the first antenna port. 
 
     
     
       9. The electronic device defined in  claim 8  wherein the second wireless transceiver has a first transceiver port coupled to the duplexer and has a second transceiver port coupled to the first antenna port. 
     
     
       10. The electronic device defined in  claim 9  wherein the second wireless transceiver is configured to handle cellular telephone communications frequencies in a communications band from 700 MHz to 960 MHz over the second transceiver port and is configured to handle Long Term Evolution band 38 and 40 communications over the first transceiver port. 
     
     
       11. The electronic device defined in  claim 10  wherein the first wireless transceiver comprises a wireless local area network transceiver configured to handle 2.4 GHz and 5 GHz wireless local area network communications bands over the third antenna port. 
     
     
       12. The electronic device defined in  claim 11  further comprising:
 a first adjustable circuit interposed between the duplexer and the monopole antenna resonating element that is configured to tune the monopole antenna; and 
 a second adjustable circuit interposed between the second transceiver port and the first antenna port that is configured to tune the inverted-F antenna. 
 
     
     
       13. The electronic device defined in  claim 12  wherein the first adjustable circuit comprises a first adjustable capacitor and wherein the second adjustable circuit comprises a second adjustable capacitor. 
     
     
       14. The electronic device defined in  claim 13  further comprising a satellite navigation system receiver coupled to the second antenna port. 
     
     
       15. Apparatus, comprising:
 radio-frequency transceiver circuitry configured to handle wireless local area network signals, satellite navigation system signals, and cellular telephone signals; 
 an inverted-F antenna; 
 a first adjustable capacitor coupled between the radio-frequency transceiver circuitry and the inverted-F antenna, wherein the first adjustable capacitor is configured to tune the inverted-F antenna to handle at least some of the cellular telephone signals; 
 a monopole antenna that transmits the wireless local area network signals; and 
 a second adjustable capacitor coupled between the radio-frequency transceiver circuitry and the monopole antenna, wherein the second adjustable capacitor is configured to tune the monopole antenna to handle at least some of the cellular telephone signals. 
 
     
     
       16. The apparatus defined in  claim 15  wherein the radio-frequency transceiver circuitry comprises a first transceiver and a second transceiver, the apparatus further comprising a duplexer coupled to the second adjustable capacitor, the first transceiver, and the second transceiver. 
     
     
       17. The apparatus defined in  claim 16  wherein the inverted-F antenna includes a segment of a peripheral conductive electronic device housing structure. 
     
     
       18. The apparatus defined in  claim 17  further comprising:
 a first signal line with which the first adjustable capacitor is coupled to the segment at a first location; and 
 a second signal line that is coupled to the segment at a second location, wherein the satellite navigation system signals are conveyed to the radio-frequency transceiver circuitry using the second signal line. 
 
     
     
       19. The apparatus defined in  claim 18  further comprising a conductive structure that serves as antenna ground for the inverted-F antenna and the monopole antenna. 
     
     
       20. The electronic device defined in  claim 2 , wherein the second antenna resonating element comprises a monopole resonating element that forms a monopole antenna with the antenna ground, and the monopole resonating element is formed in a gap between the inverted-F antenna resonating element and the antenna ground. 
     
     
       21. The electronic device defined in  claim 20 , wherein the monopole resonating element has a first branch that covers a first wireless local area network frequency band and a second branch that covers a second wireless local area network frequency band, and the inverted-F antenna resonating element is coupled to the antenna ground by a short circuit path that spans the gap and that overlaps a portion of the monopole resonating element in the gap. 
     
     
       22. The electronic device defined in  claim 8 , wherein the first wireless transceiver receives radio-frequency signals from the third antenna port through the duplexer and the second wireless transceiver receives radio-frequency signals from the third antenna port through the duplexer and from the first antenna port.

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. 
     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 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 
     An electronic device may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may have multiple antenna ports such as first, second, and third ports. The transceiver circuitry may include a satellite navigation system receiver, a wireless local area network transceiver, and a cellular transceiver for handling cellular voice and data traffic. 
     A duplexer may be coupled to the third port. The wireless local area network transceiver may have a port that is coupled to the duplexer. The cellular transceiver may also have a port that is coupled to the duplexer. The satellite navigation system receiver may be coupled to the second port. The cellular transceiver may be coupled to the first port. 
     The antenna structures may include an inverted-F antenna resonating element that forms an inverted-F antenna with an antenna ground. The antenna structures may also include a monopole antenna resonating element that forms a monopole antenna with the antenna ground. The first and second antenna ports may be formed by signal lines that are coupled to the inverted-F antenna resonating element at different locations. The third antenna port may be coupled to the monopole antenna resonating element. 
     A first adjustable capacitor may be coupled to the first port of the inverted-F antenna to tune the inverted-F antenna. For example, the first adjustable capacitor may be used to tune the antenna structures to cover a desired range of cellular communications. 
     An additional adjustable capacitor may be coupled to the third port to tune the monopole antenna. For example, the additional adjustable capacitor may be used to ensure that the monopole antenna can be used in handling wireless local area network frequencies and cellular frequencies of interest. 
     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 an illustrative tunable antenna in accordance with an embodiment of the present invention. 
         FIG. 4  is a diagram of an illustrative adjustable capacitor of the type that may be used in tuning antenna structures in an electronic device in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram of illustrative electronic device antenna structures having a dual arm inverted-F antenna resonating element with two antenna ports that is formed from a housing structure and having a monopole antenna resonating element coupled to another antenna port in accordance with an embodiment of the present invention. 
         FIG. 6  is a graph of antenna performance as a function of frequency for a tunable antenna of the type shown in  FIG. 5  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 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 peripheral structures such as 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, and/or may form other housing structures. Gaps in the peripheral conductive member may be associated with the antennas. 
     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, 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 layer of clear glass or plastic may cover the surface of display  14 . Buttons such as button  19  may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port  26 . 
     Housing  12  may include peripheral housing structures such as structures  16 . Structures  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, structures  16  may be implemented using a peripheral housing member have a rectangular ring shape (as an example). Peripheral structures  16  or part of peripheral structures  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 ). Peripheral structures  16  may also, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, etc.). 
     Peripheral housing structures  16  may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, or a peripheral conductive housing member (as examples). Peripheral housing structures  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 peripheral housing structures  16 . 
     It is not necessary for peripheral housing structures  16  to have a uniform cross-section. For example, the top portion of peripheral housing structures  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. If desired, the bottom portion of peripheral housing structures  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 , peripheral housing structures  16  have substantially straight vertical sidewalls. This is merely illustrative. The sidewalls formed by peripheral housing structures  16  may be curved or may have other suitable shapes. In some configurations (e.g., when peripheral housing structures  16  serve as a bezel for display  14 ), peripheral housing structures  16  may run around the lip of housing  12  (i.e., peripheral housing structures  16  may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, housing  12  may have a conductive rear surface. For example, housing  12  may be formed from a metal such as stainless steel or aluminum. The rear surface of housing  12  may lie in a plane that is parallel to display  14 . In configurations for device  10  in which the rear surface of housing  12  is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  16  as integral portions of the housing structures forming the rear surface of housing  12 . For example, a rear housing wall of device  10  may be formed from a planar metal structure and portions of peripheral housing structures  16  on the left and right sides of housing  12  may be formed as vertically extending integral metal portions of the planar metal structure. Housing structures such as these may, if desired, be machined from a block of metal. 
     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 housing member (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more parts 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 may be formed within the conductive structures of device  10  (e.g., between peripheral conductive housing structures  16  and opposing conductive structures such as conductive housing midplate or rear housing wall structures, a conductive ground plane associated with a printed circuit board, and conductive electrical components in device  10 ). These openings, which may sometimes be referred to as gaps, 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 from the ground plane, may contribute to the performance of a parasitic antenna resonating element, 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 peripheral housing structures  16  may be provided with gap structures. For example, peripheral housing structures  16  may be provided with one or more gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral housing structures  16  may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide peripheral housing structures  16  into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral housing structures  16  (e.g., in an arrangement with two gaps), three peripheral conductive segments (e.g., in an arrangement with three gaps), four peripheral conductive segments (e.g., in an arrangement with four gaps, etc.). The segments of peripheral conductive housing structures  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 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 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, 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, 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, filters, duplexers, 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 such as 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 in frequency ranges of about 700 MHz to about 2700 MHz or bands at higher or lower frequencies. 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 wireless circuitry for receiving radio and television signals, paging circuits, etc. Near field communications may also be supported (e.g., at 13.56 MHz). 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 have antenna structures such as one or more antennas  40 . Antennas structures  40  may be formed using any suitable antenna types. For example, antennas structures  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, dual arm 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. Antenna structures in device  10  such as one or more of antennas  40  may be provided with one or more antenna feeds, fixed and/or adjustable components, and optional parasitic antenna resonating elements so that the antenna structures cover desired communications bands. 
     Illustrative antenna structures of the type that may be used in device  10  (e.g., in region  20  and/or region  22 ) are shown in  FIG. 3 . Antenna structures  40  of  FIG. 3  include an antenna resonating element of the type that is sometimes referred to as a dual arm inverted-F antenna resonating element or T antenna resonating element. As shown in  FIG. 3 , antenna structures  40  may have conductive antenna structures such as dual arm inverted-F antenna resonating element  50 , optional additional antenna resonating element  132  (which may operate as a near-field coupled parasitic antenna resonating element and/or a directly fed antenna resonating element), and antenna ground  52 . The conductive structures that form antenna resonating element  50 , antenna resonating element  132 , and antenna ground  52  may be formed from parts of conductive housing structures, from parts of electrical device components in device  10 , from printed circuit board traces, from strips of conductor such as strips of wire and metal foil, or may be formed using other conductive structures. 
     Antenna resonating element  50  and antenna ground  52  may form first antenna structures  40 A (e.g., a first antenna such as a dual arm inverted-F antenna). Resonating element  132  and antenna ground  52  may form second antenna structures  40 B (e.g., a second antenna). If desired, resonating element  132  may also form a parasitic antenna resonating element (e.g., an element that is not directly fed). Resonating element  132  may, for example, form a parasitic antenna element that contributes to the response of antenna  40 A during operation of antenna structures  40  at certain frequencies. 
     As shown in  FIG. 3 , transceiver circuitry  90  may be coupled to antenna  40  using transmission line structures such as transmission line  92 . Transmission line  92  may have positive signal path  92 A and ground signal path  92 B. Paths  92 A and  92 B may be formed from metal traces on rigid printed circuit boards, may be formed from metal traces on flexible printed circuits, may be formed on dielectric support structures such as plastic, glass, and ceramic members, may be formed as part of a cable, etc. Transmission line  92  may be formed using one or more microstrip transmission lines, stripline transmission lines, edge coupled microstrip transmission lines, edge coupled stripline transmission lines, coaxial cables, or other suitable transmission line structures. Circuits such as impedance matching circuits, filters, switches, duplexers, diplexers, and other circuitry may, if desired, be interposed in transmission line path  92 . 
     Transmission line structures  92  may be coupled to antenna ports formed using antenna port terminals  94 - 1  and  96 - 1  (which form a first antenna port), antenna port terminals  94 - 2  and  96 - 2  (which form a second antenna port), and antenna port terminals  94 - 3  and  96 - 3  (which form a third antenna port). The antenna ports may sometimes be referred to as antenna feeds. For example, terminal  94 - 1  may be a positive antenna feed terminal and terminal  96 - 1  may be a ground antenna feed terminal for a first antenna feed, terminal  94 - 2  may be a positive antenna feed terminal and terminal  96 - 2  may be a ground antenna feed terminal for a second antenna feed, and terminal  94 - 3  may be a positive antenna feed terminal and terminal  96 - 3  may be a ground antenna feed terminal for a third antenna feed. 
     Each antenna port in antenna structures  40  may be used in handling a different type of wireless signals. For example, the first port may be used for transmitting and/or receiving antenna signals in a first communications band or first set of communications bands, the second port may be used for transmitting and/or receiving antenna signals in a second communications band or second set of communications bands, and the third port may be used for transmitting and/or receiving antenna signals in a third communications band or third set of communications bands. 
     If desired, tunable components such as adjustable capacitors, adjustable inductors, filter circuitry, switches, impedance matching circuitry, duplexers, and other circuitry may be interposed within transmission line paths (i.e., between wireless circuitry  90  and the respective ports of antenna structures  40 ). The different ports in antenna structures  40  may each exhibit a different impedance and antenna resonance behavior as a function of operating frequency. Wireless circuitry  90  may therefore use different ports for different types of communications. As an example, signals associated with communicating in one or more cellular communications band may be transmitted and received using one of the ports, whereas reception of satellite navigation system signals may be handled using a different one of the ports. 
     Antenna resonating element  50  may include a short circuit branch such as branch  98  that couples resonating element arm structures such as arms  100  and  102  to antenna ground  52 . Dielectric gap  101  separates arms  100  and  102  from antenna ground  52 . Antenna ground  52  may be formed from housing structures such as a metal midplate member, printed circuit traces, metal portions of electronic components, or other conductive ground structures. Gap  101  may be formed by air, plastic, and other dielectric materials. Short circuit branch  98  may be implemented using a strip of metal, a metal trace on a dielectric support structure such as a printed circuit or plastic carrier, or other conductive path that bridges gap  101  between resonating element arm structures (e.g., arms  102  and/or  100 ) and antenna ground  52 . 
     The antenna port formed from terminals  94 - 1  and  96 - 1  may be coupled in a path such as path  104 - 1  that bridges gap  101 . The antenna port formed from terminals  94 - 2  and  96 - 2  may be coupled in a path such as path  104 - 2  that bridges gap  101  in parallel with path  104 - 1  and short circuit path  98 . 
     Resonating element arms  100  and  102  may form respective arms in a dual arm inverted-F antenna resonating element. Arms  100  and  102  may have one or more bends. The illustrative arrangement of  FIG. 3  in which arms  100  and  102  run parallel to ground  52  is merely illustrative. 
     Arm  100  may be a (longer) low-band arm that handles lower frequencies, whereas arm  102  may be a (shorter) high-band arm that handles higher frequencies. Low-band arm  100  may allow antenna  40  to exhibit an antenna resonance at low band (LB) frequencies such as frequencies from 700 MHz to 960 MHz or other suitable frequencies. High-band arm  102  may allow antenna  40  to exhibit one or more antenna resonances at high band (HB) frequencies such as resonances at one or more ranges of frequencies between 960 MHz to 2700 MHz or other suitable frequencies. Antenna resonating element  101  may also exhibit an antenna resonance at 1575 MHz or other suitable frequency for supporting satellite navigation system communications such as Global Positioning System communications. 
     Antenna resonating element  132  may be used to support communications at additional frequencies (e.g., frequencies associated with a 2.4 GHz communications band such as an IEEE 802.11 wireless local area network band, a 5 GHz communications band such as an IEEE 802.11 wireless local area network band, and/or cellular frequencies such as frequencies in cellular bands near 2.4 GHz). 
     Antenna resonating element  132  may be based on a monopole antenna resonating element structure that forms a monopole antenna using antenna ground  52  or may be formed from other antenna resonating element structures. Antenna resonating element  132  may be formed from strips of metal (e.g., stamped metal foil), metal traces on a flexible printed circuit (e.g., a printed circuit formed from a flexible substrate such as a layer of polyimide or a sheet of other polymer material), metal traces on a rigid printed circuit board substrate (e.g., a substrate formed from a layer of fiberglass-filled epoxy), metal traces on a plastic carrier, patterned metal on glass or ceramic support structures, wires, electronic device housing structures, metal parts of electrical components in device  10 , or other conductive structures. 
     To provide antenna  40  with tuning capabilities, antenna  40  may include adjustable circuitry. The adjustable circuitry may be coupled between different locations on antenna resonating element  50 , may be coupled between different locations on resonating element  132 , may form part of paths such as paths  104 - 1  and  104 - 2  that bridge gap  101 , may form part of transmission line structures  92  (e.g., circuitry interposed within one or more of the conductive lines in path  92 - 1 , path  92 - 2 , and/or path  92 - 3 ), or may be incorporated elsewhere in antenna structures  40 , transmission line paths  92 , and wireless circuitry  90 . 
     The adjustable circuitry may be tuned using control signals from control circuitry  28  ( FIG. 2 ). Control signals from control circuitry  28  may, for example, be provided to an adjustable capacitor, adjustable inductor, or other adjustable circuit using a control signal path that is coupled between control circuitry  28  and the adjustable circuit. Control circuitry  28  may provide control signals to adjust a capacitance exhibited by an adjustable capacitor, may provide control signals to adjust the inductance exhibited by an adjustable inductor, may provide control signals that adjust the impedance of a circuit that includes one or more components such fixed and variable capacitors, fixed and variable inductors, switching circuitry for switching electrical components such as capacitors and inductors into and out of use, resistors, and other adjustable circuitry, or may provide control signals to other adjustable circuitry for tuning the frequency response of antenna structures  40 . As an example, antenna structures  40  may be provided with first and second adjustable capacitors. By selecting a desired capacitance value for each adjustable capacitor using control signals from control circuitry  28 , antenna structures  40  can be tuned to cover operating frequencies of interest. 
     If desired, the adjustable circuitry of antenna structures  40  may include one or more adjustable circuits that are coupled to antenna resonating element structures  50  such as arms  102  and  100  in antenna resonating element  50 , one or more adjustable circuits that are coupled to a monopole antenna resonating element (e.g., resonating element  132 ), one or more adjustable circuits that are interposed within the signal lines associated with one or more of the ports for antenna structures  40  (e.g., paths  104 - 1 ,  104 - 2 , paths  92 , etc.). 
       FIG. 4  is a schematic diagram of an illustrative adjustable capacitor circuit of the type that may be used in tuning antenna structures  40 . Adjustable capacitor  106  of  FIG. 4  produces an adjustable amount of capacitance between terminals  114  and  115  in response to control signals provided to input path  108 . Switching circuitry  118  has two terminals coupled respectively to capacitors C 1  and C 2  and has another terminal coupled to terminal  115  of adjustable capacitor  106 . Capacitor C 1  is coupled between terminal  114  and one of the terminals of switching circuitry  118 . Capacitor C 2  is coupled between terminal  114  and the other terminal of switching circuitry  118  in parallel with capacitor C 1 . By controlling the value of the control signals supplied to control input  108 , switching circuitry  118  may be configured to produce a desired capacitance value between terminals  114  and  115 . For example, switching circuitry  118  may be configured to switch capacitor C 1  into use or may be configured to switch capacitor C 2  into use. 
     If desired, switching circuitry  118  may include one or more switches or other switching resources that selectively decouple capacitors C 1  and C 2  (e.g., by forming an open circuit so that the path between terminals  114  and  115  is an open circuit and both capacitors are switched out of use). Switching circuitry  118  may also be configured (if desired) so that both capacitors C 1  and C 2  can be simultaneously switched into use. Other types of switching circuitry  118  such as switching circuitry that exhibits fewer switching states or more switching states may be used if desired. Adjustable capacitors such as adjustable capacitor  106  may also be implemented using variable capacitor devices (sometimes referred to as varactors). Adjustable capacitors such as capacitor  106  may include two capacitors, three capacitors, four capacitors, or other suitable numbers of capacitors. The configuration of  FIG. 4  is merely illustrative. 
     During operation of device  10 , control circuitry such as storage and processing circuitry  28  of  FIG. 2  may make antenna adjustments by providing control signals to adjustable components such as one or more adjustable capacitors  106 . If desired, control circuitry  28  may also make antenna tuning adjustments using adjustable inductors or other adjustable circuitry. Antenna frequency response adjustments may be made in real time in response to information identifying which communications bands are active, in response to feedback related to signal quality or other performance metrics, in response to sensor information, or based on other information. 
       FIG. 5  is a diagram of an electronic device with illustrative adjustable antenna structures  40 . In the illustrative configuration of  FIG. 5 , electronic device  10  has adjustable antenna structures  40  that are implemented using conductive housing structures in electronic device  10 . As shown in  FIG. 5 , antenna structures  40  include antenna resonating element  132  and antenna resonating element  50 . Antenna resonating element  132  may be a monopole antenna resonating element. Antenna resonating element  132  and antenna ground  52  may form antenna  40 B (e.g., a monopole antenna). Antenna resonating element  50  may be a dual arm inverted-F antenna resonating element. Antenna resonating element  50  and antenna ground  52  may form antenna  40 A (e.g., a dual arm inverted-F antenna). 
     Arms  100  and  102  of dual arm inverted-F antenna resonating element  50  may be formed from portions of peripheral conductive housing structures  16 . Resonating element arm portion  102  of resonating element  50  in antenna  40 A produces an antenna response in a high band (HB) frequency range and resonating element arm portion  100  produces an antenna response in a low band (LB) frequency range. Antenna ground  52  may be formed from sheet metal (e.g., one or more housing midplate members and/or a rear housing wall in housing  12 ), may be formed from portions of printed circuits, may be formed from conductive device components, or may be formed from other metal portions of device  10 . 
     As described in connection with  FIG. 3 , antenna structures  40  may have three antenna ports. Port  1 A may be coupled to the antenna resonating element arms of dual arm antenna resonating element  50  at a first location along member  16  (see, e.g., path  92 - 1 A, which is coupled to member  16  at terminal  94 - 1 ). Port  1 B may be coupled to the antenna resonating element arm structures of dual arm antenna resonating element  50  at a second location that is different than the first location (see, e.g., path  92 - 2 A, which is coupled to member  16  at terminal  94 - 2 ). 
     Adjustable capacitor  106 A (e.g., a capacitor of the type shown in  FIG. 4 ) may be interposed in path  94 - 1 A and coupled to port  1 A for use in tuning antenna structures  40  (e.g., for tuning dual arm inverted-F antenna  40 A). Global positioning system (GPS) signals may be received using port  1 B of antenna  40 A. Transmission line path  92 - 2  may be coupled between port  1 B and satellite navigation system receiver  114  (e.g., a Global Positioning System receiver such as satellite navigation system receiver  35  of  FIG. 2 ). Circuitry such as band pass filter  110  and amplifier  112  may, if desired, be interposed within transmission line path  92 - 2 . During operation, satellite navigation system signals may pass from antenna  40 A to receiver  114  via filter  110  and amplifier  112 . 
     Antenna resonating element  50  may cover frequencies such as frequencies in a low band (LB) communications band extending from about 700 MHz to 960 MHz and, if desired, a high band (HB) communications band extending from about 1.7 to 2.2 GHz (as examples). Adjustable capacitor  106 A may be used in tuning low band performance in band LB, so that all desired frequencies between 700 MHz and 960 MHz can be covered. 
     Port  2  may use signal line  92 - 3 A to feed antenna resonating element  132  of antenna  40 B at feed terminal  94 - 3 . In the illustrative arrangement of  FIG. 5 , antenna resonating element  132  is a monopole antenna resonating element in monopole antenna  40 B. Monopole antenna resonating element  132  has two branches that are used in forming a dual-band antenna with antenna ground  52 . The dual-band monopole antenna may exhibit a resonance at a communications band at 5 GHz (e.g., for handling 5 GHz wireless local area network communications) and a resonance at a communications band at 2.4 GHz. Antenna response in the 2.4 GHz band may be tuned using adjustable capacitor  106 A (e.g. a capacitor of the type shown in  FIG. 4 ). By tuning the monopole antenna formed from antenna resonating element  132 , the monopole antenna may be adjusted to cover a range of desired frequencies in a band that extends from a low frequency of about 2.3 GHz to a high frequency of about 2.7 GHz (as an example). This allows the monopole antenna to cover both wireless local area network traffic at 2.4 GHz and some of the cellular traffic for device  10 . 
     Wireless circuitry  90  may include satellite navigation system receiver  114  and radio-frequency transceiver circuitry such as radio-frequency transceiver circuitry  116  and  118 . Receiver  114  may be a Global Positioning System receiver or other satellite navigation system receiver (e.g., receiver  35  of  FIG. 2 ). Transceiver  116  may be a wireless local area network transceiver such as radio-frequency transceiver  36  of  FIG. 2  that operates in bands such as a 2.4 GHz band and a 5 GHz band. Transceiver  116  may be, for example, an IEEE 802.11 radio-frequency transceiver (sometimes referred to as a WiFi® transceiver). Transceiver  118  may be a cellular transceiver such as cellular transceiver  38  of  FIG. 2  that is configured to handle voice and data traffic in one or more cellular bands. Examples of cellular bands that may be covered include a band (e.g., low band LB) ranging from 700 MHz to 960 MHz, a band (e.g., a high band HB) ranging from about 1.7 to 2.2 GHz), and Long Term Evolution (LTE) bands 38 and 40. 
     Long Term Evolution band 38 is associated with frequencies of about 2.6 GHz. Long Term Evolution band 40 is associated with frequencies of about 2.3 to 2.4 GHz. Port CELL of transceiver  118  may be used to handle cellular signals in band LB (700 MHz to 960 MHz) and, if desired, in band HB (1.7 to 2.2 GHz). Port CELL is coupled to port  1 A of antenna structures  40 . Port LTE 38/40 of transceiver  118  is used to handle communications in LTE band 38 and LTE band 40. As shown in  FIG. 5 , port LTE 38/40 of transceiver  118  may be coupled to port  122  of duplexer  120 . Port  124  of duplexer  120  may be coupled to the input-output port of transceiver  116 , which handles WiFi® signals at 2.4 and 5 GHz. 
     Duplexer  120  uses frequency multiplexing to route the signals between ports  122  and  124  and shared duplexer port  126 . Port  126  is coupled to transmission line path  92 - 3 . With this arrangement, 2.4 GHz and 5 GHz WiFi® signals associated with port  124  of duplexer  120  and transceiver  116  may be routed to and from path  92 - 3  and LTE band 38/40 signals associated with port  122  of duplexer  120  and port LTE 38/40 of transceiver  118  may be routed to and from path  92 - 3 . Adjustable capacitor  106 B can be coupled between duplexer  120  and antenna resonating element  132 . During operation of device  10 , adjustable capacitor  106 B can be adjusted to tune the monopole antenna formed from antenna resonating element  132  as needed to handle the 2.4/5 GHz traffic associated with port  124  and the LTE band 38/40 traffic associated with port  122 . 
       FIG. 6  is a graph in which antenna performance (standing wave ratio SWR) has been plotted as a function of operating frequency for a device with antenna structures such as antenna structures  40  of  FIG. 5 . As shown in  FIG. 6 , antenna structures  40  may exhibit a resonance at band LB using port  1 A. Adjustable capacitor  106 A may be adjusted to adjust the position of the LB resonance, thereby covering all frequencies of interest (e.g., all frequencies in a range of about 0.7 GHz to 0.96 GHz, as an example). When using port  1 B, antenna structures  40  may exhibit a resonance at a satellite navigation system frequency such as a 1.575 GHz resonance for handling Global Positioning System signals. Band HB (e.g., a cellular band from 1.7 to 2.2 GHz) may optionally be covered using port  1 A (with our without using adjustable capacitor  106 A to cover frequencies of interest). 
     Using port  2  and the monopole antenna formed from antenna resonating element  132  and antenna ground  52 , antenna structures  40  may cover communications band UB. Adjustable capacitor  106 B may be adjusted to tune the position of the UB antenna resonance, thereby ensuring that the UB resonance can cover all desired frequencies of interest (e.g., frequencies ranging from 2.3 GHz to 2.7 GHz, as an example). For example, adjustable capacitor  106 B may be adjusted to ensure that 2.3-2.4 GHz LTE band 40 signals from port  122  can be covered, to ensure that 2.4 GHz WiFi® signals from port  124  can be handled, and to ensure that 2.6 GHz LTE band 38 signals from port  122  can be handled. Band TB (e.g., a band at 5 GHz for handling 5 GH WiFi® signals from port  124 ) may be covered using the monopole antenna formed from antenna resonating element  132  and antenna ground  52 . 
     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: 20130318
Publication Date: 20170131
Grant Date: 20170131
Priority Date: 20130318
Inventors: ZHOU YIJUN
JIN NANBO
OUYANG YUEHUI
VAZQUEZ ENRIQUE AYALA
LAKSHMANAN ANAND
SCHLUB ROBERT W.
PASCOLINI MATTIA
MOW MATTHEW A.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/24", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 50071755