PATENT DOCUMENT

Publication Number: US-10367570-B2
Application Number: US-201715701233-A
Country: US
Kind Code: B2

Title: Electronic devices having printed circuits for antennas

Abstract:
An electronic device may be provided with antenna structures and control circuitry. The antenna structures may include an antenna resonating element arm, an antenna ground, and an antenna feed coupled between the antenna resonating element arm and the antenna ground. The electronic device may include a tunable component configured to tune a frequency response of the antenna structures. The electronic device may also include a substrate, a radio-frequency transceiver on the substrate, control circuitry configured to generate control signals, a flexible printed circuit, and a connector. The connector may mechanically secure the flexible printed circuit to the substrate and may be electrically coupled to the transceiver and the control circuitry. The flexible printed circuit may include a radio-frequency transmission line coupled between the antenna feed and the connector and a control signal path coupled between the tunable component and the connector.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a substrate; 
 a radio-frequency transceiver; 
 control circuitry configured to generate control signals; 
 an antenna that includes an antenna resonating element arm, an antenna ground, and an antenna feed coupled between the antenna resonating element arm and the antenna ground; 
 a tunable component coupled to the antenna and configured to tune a frequency response of the antenna; 
 a flexible printed circuit; and 
 a connector that mechanically secures the flexible printed circuit to the substrate and that is electrically coupled to the radio-frequency transceiver and the control circuitry, wherein the flexible printed circuit comprises a radio-frequency transmission line coupled between the antenna feed and the connector and a control signal path coupled between the tunable component and the connector, the connector is configured to convey the radio-frequency signals between the radio-frequency transceiver and the radio-frequency transmission line on the flexible printed circuit, and the connector is configured to convey the control signals from the control circuitry to the control signal path on the flexible printed circuit. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the antenna is a first antenna, the antenna resonating element arm is a first antenna resonating element arm, the antenna feed is a first antenna feed, and the radio-frequency transmission line is a first radio-frequency transmission line, the electronic device further comprising:
 a second antenna that includes a second antenna resonating element arm, the antenna ground, and a second antenna feed coupled between the second antenna resonating element arm and the antenna ground, wherein the flexible printed circuit comprises a second radio-frequency transmission line coupled between the second antenna feed and the connector. 
 
     
     
       3. The electronic device defined in  claim 2 , further comprising:
 a third antenna that includes a third antenna resonating element arm, the antenna ground, and a third antenna feed coupled between the third antenna resonating element arm and the antenna ground, wherein the flexible printed circuit comprises a third radio-frequency transmission line coupled between the third antenna feed and the connector. 
 
     
     
       4. The electronic device defined in  claim 3 , wherein the first antenna is configured to convey radio-frequency signals in a first frequency band, the second antenna is configured to convey radio-frequency signals in a second frequency band that is different than the first frequency band, and the third antenna is configured to convey radio-frequency signals in a third frequency band that is different than the first and second frequency bands. 
     
     
       5. The electronic device defined in  claim 4 , wherein the first frequency band comprises frequencies between 1710 MHz and 2170 MHz, the second frequency band comprises frequencies between 5150 MHz and 5850 MHz, and the third frequency band comprises frequencies between 3400 MHz and 3700 MHz. 
     
     
       6. The electronic device defined in  claim 4 , wherein the first antenna resonating element arm has opposing first and second ends, the first antenna feed comprises a positive feed terminal coupled to the first antenna resonating element arm and a ground feed terminal coupled to the antenna ground, the second antenna is interposed between the first end of the first antenna resonating element arm and the ground feed terminal, and the third antenna is interposed between the second end of the first antenna resonating element arm and the ground feed terminal. 
     
     
       7. The electronic device defined in  claim 6 , wherein the antenna ground has a first edge that runs along a first side of the second antenna, a second edge that runs along a second side of the second antenna, a third edge that runs along a first side of the third antenna and a fourth edge that runs along a second side of the fourth antenna. 
     
     
       8. The electronic device defined in  claim 6 , further comprising:
 a housing having peripheral conductive structures and a planar conductive layer extending between first and second segments of the peripheral conductive structures; 
 a first dielectric-filled gap in the peripheral conductive structures that separates the first segment from a third segment of the peripheral conductive structures; 
 a second dielectric-filled gap in the peripheral conductive structures that separates the second segment from the third segment, wherein the third segment of the peripheral conductive structures defines the first antenna resonating element arm, the antenna ground includes the planar conductive layer and the first and second segments of the peripheral conductive structures, the first end of the first antenna resonating element arm is defined by the first dielectric-filled gap, and the second end of the first antenna resonating element arm is defined by the second dielectric-filled gap. 
 
     
     
       9. The electronic device defined in  claim 8 , further comprising:
 a conductive fastener that mechanically secures and electrically connects the flexible printed circuit to the planar conductive layer. 
 
     
     
       10. The electronic device defined in  claim 8 , further comprising:
 a display, wherein the antenna ground includes a conductive portion of the display. 
 
     
     
       11. The electronic device defined in  claim 4 , wherein the flexible printed circuit further comprises:
 a flexible polymer substrate; 
 upper and lower ground layers supported by the flexible polymer substrate; 
 a first signal path for the first radio-frequency transmission line that is embedded within the flexible polymer substrate and interposed between the upper and lower ground layers; 
 a second signal path for the second radio-frequency transmission line that is embedded within the flexible polymer substrate and interposed between the upper and lower ground layers; 
 a first fence of conductive vias that is coupled between the upper and lower ground layers and that extends through the flexible polymer substrate, wherein the first fence of conductive vias is interposed between the first signal path and the control signal path and the first fence of conductive vias is configured to electromagnetically isolate the control signal path from radio-frequency signals in the first frequency band conveyed over the first radio-frequency transmission line; and 
 a second fence of conductive vias that is coupled between the upper and lower ground layers and that extend through the flexible polymer substrate, wherein the second fence of conductive vias is interposed between the second signal path and the control signal path and the second fence of conductive vias is configured to electromagnetically isolate the control signal path from radio-frequency signals in the second frequency band conveyed over the second radio-frequency transmission line. 
 
     
     
       12. The electronic device defined in  claim 1 , further comprising:
 a sensor mounted on the flexible printed circuit; and 
 an additional control signal path coupled between the sensor and the connector. 
 
     
     
       13. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 an antenna ground; 
 a first antenna resonating element formed from the peripheral conductive structures and configured to convey radio-frequency signals in a first frequency band, the first antenna resonating element having opposing first and second ends; 
 an antenna feed having a positive feed terminal coupled to the first antenna resonating element and a ground feed terminal coupled to the antenna ground; 
 a second antenna resonating element interposed between the first end of the first antenna resonating element and the ground feed terminal and configured to convey radio-frequency signals in a second frequency band; 
 a third antenna resonating element interposed between the second end of the first antenna resonating element and the ground feed terminal and configured to convey radio-frequency signals in a third frequency band; and 
 a flexible printed circuit coupled to the first, second, and third antenna resonating elements. 
 
     
     
       14. The electronic device defined in  claim 13 , wherein the flexible printed circuit comprises a first radio-frequency transmission line coupled to the antenna feed, a second radio-frequency transmission line coupled to a first additional antenna feed associated with the second antenna resonating element, and a third radio-frequency transmission line coupled to a second additional antenna feed associated with the third antenna resonating element. 
     
     
       15. The electronic device defined in  claim 14 , further comprising:
 a tunable component configured to tune a frequency response of the antenna, wherein the flexible printed circuit further comprises a digital control line that conveys digital control signals to the tunable component. 
 
     
     
       16. The electronic device defined in  claim 13 , wherein the antenna ground has a first edge that runs along a first side of the second antenna resonating element, a second edge that runs along a second side of the second antenna resonating element, a third edge that runs along a first side of the third antenna resonating element, and a fourth edge that runs along a second side of the third antenna resonating element. 
     
     
       17. A flexible printed circuit comprising:
 a flexible polymer substrate; 
 upper and lower ground layers supported by the flexible polymer substrate; 
 a signal path for a radio-frequency transmission line that is embedded within the flexible polymer substrate and interposed between the upper and lower ground layers; 
 a first plurality of conductive vias that are coupled between the upper and lower ground layers and that extend through the flexible polymer substrate; and 
 a plurality of digital control lines embedded within the flexible polymer substrate, wherein the first plurality of conductive vias are interposed between the signal path and the plurality of digital control lines and the first plurality of conductive vias are configured to electromagnetically isolate the plurality of digital control lines from radio-frequency signals conveyed over the radio-frequency transmission line. 
 
     
     
       18. The flexible printed circuit defined in  claim 17 , further comprising:
 a second plurality of conductive vias that are coupled between the upper and lower ground layers and that extend through the flexible polymer substrate, wherein the plurality of digital signal control lines are interposed between the first plurality of conductive vias and the second plurality of conductive vias. 
 
     
     
       19. The flexible printed circuit defined in  claim 18 , further comprising:
 an additional signal path for an additional radio-frequency transmission line that is embedded within the flexible polymer substrate and interposed between the upper and lower ground layers, wherein the second plurality of conductive vias are interposed between the additional signal path and the plurality of digital control lines and the second plurality of conductive vias are configured to electromagnetically isolate the plurality of digital control lines from radio-frequency signals conveyed over the additional radio-frequency transmission line. 
 
     
     
       20. The flexible printed circuit defined in  claim 18 , further comprising:
 a third plurality of conductive vias that are coupled between the upper and lower ground layers and that extend through the flexible polymer substrate, wherein the signal path is interposed between the first plurality of conductive vias and the third plurality of conductive vias; and 
 an additional signal path for an additional radio-frequency transmission line that is embedded within the flexible polymer substrate and interposed between the upper and lower ground layers, wherein the third plurality of conductive vias are interposed between the signal path and the additional signal path and the third plurality of conductive vias are configured to electromagnetically isolate the signal path from radio-frequency signals conveyed over the additional radio-frequency transmission line.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless communications circuitry. For example, cellular telephones, computers, and other devices often contain antennas and wireless transceivers for supporting wireless communications. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, antennas are bulky. In other devices, antennas are compact, but are sensitive to the position of the antennas relative to external objects. If care is not taken, antennas may become detuned, may emit wireless signals with a power that is more or less than desired, or may otherwise not perform as expected. In addition, if care is not taken, it can be difficult to convey radio-frequency signals over multiple antennas while ensuring that the radio-frequency signals are sufficiently isolated. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry and control circuitry. The wireless circuitry may include multiple antennas and transceiver circuitry. The antennas may include antenna structures at opposing first and second ends of the electronic device. The antenna structures at a given end of the device may include multiple antennas and adjustable components that are adjusted by the control circuitry to place the antenna structures and the electronic device in one of a number of different operating modes or states. 
     The antenna structures at a first end of the electronic device may include a first antenna. The first antenna may include a first antenna resonating element arm, an antenna ground, and an antenna feed coupled between the first antenna resonating element arm and the antenna ground. The antenna feed may include a positive feed terminal coupled to the first antenna resonating element arm and a ground feed terminal coupled to the antenna ground. The electronic device may include a tunable component configured to tune a frequency response of the first antenna. The electronic device may also include a substrate, a radio-frequency transceiver on the substrate, control circuitry configured to generate control signals, a flexible printed circuit, and a connector. 
     The connector may mechanically secure the flexible printed circuit to the substrate and may be electrically coupled to the radio-frequency transceiver and the control circuitry. The flexible printed circuit may include a radio-frequency transmission line coupled between the antenna feed and the connector and a control signal path coupled between the tunable component and the connector. The connector may convey radio-frequency signals between the radio-frequency transceiver and the radio-frequency transmission line on the flexible printed circuit and may convey the control signals from the control circuitry to the control signal path on the flexible printed circuit. 
     The antenna structures at the first end of the electronic device may also include a second antenna and a third antenna. The second antenna may have a second antenna resonating element arm interposed between a first end of the first antenna resonating element arm and the ground feed terminal of the first antenna. The third antenna may have a third antenna resonating element arm interposed between a second end of the first antenna resonating element arm and the ground feed terminal of the first antenna. The flexible printed circuit may be coupled to the second and third antennas as well as the first antenna. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 3  is a schematic diagram of illustrative wireless communications circuitry in accordance with an embodiment. 
         FIG. 4  is a schematic diagram of an illustrative inverted-F antenna in accordance with an embodiment. 
         FIG. 5  is a top view of illustrative antenna structures in an electronic device in accordance with an embodiment. 
         FIG. 6  is a top view of an illustrative flexible printed circuit board for supporting antenna structures of the type shown in  FIG. 5  in accordance with an embodiment. 
         FIG. 7  is a top view of an illustrative flexible printed circuit of the type shown in  FIG. 6  in accordance with embodiment. 
         FIG. 8  is a cross-sectional side view of an illustrative flexible printed circuit of the type shown in  FIG. 6  in accordance with an embodiment. 
         FIG. 9  is a cross-sectional side view of an illustrative flexible printed circuit having varying local thicknesses in accordance with an embodiment. 
     
    
    
     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 more antennas. The antennas of the wireless communications circuitry 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 peripheral conductive structures that run around the periphery of an electronic device. The peripheral conductive structures may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. 
     Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for electronic device  10 . Antennas may also be formed using an antenna ground plane and/or an antenna resonating element formed from conductive housing structures (e.g., internal and/or external structures, support plate structures, etc.). 
     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 handheld device such as a cellular telephone, a media player, or other small portable device. Device  10  may also be a set-top box, a desktop computer, a display into which a computer or other processing circuitry has been integrated, a display without an integrated computer, 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 (e.g., glass, ceramic, plastic, sapphire, etc.). 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 be mounted on the front face of device  10 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. The rear face of housing  12  (i.e., the face of device  10  opposing the front face of device  10 ) may have a planar housing wall. The rear housing wall may have slots that pass entirely through the rear housing wall and that therefore separate housing wall portions (and/or sidewall portions) of housing  12  from each other. The rear housing wall may include conductive portions and/or dielectric portions. If desired, the rear housing wall may include a planar metal layer covered by a thin layer or coating of dielectric such as glass, plastic, sapphire, or ceramic. Housing  12  (e.g., the rear housing wall, sidewalls, etc.) may also have shallow grooves that do not pass entirely through housing  12 . The slots and grooves may be filled with plastic or other dielectric. If desired, portions of housing  12  that have been separated from each other (e.g., by a through slot) may be joined by internal conductive structures (e.g., sheet metal or other metal members that bridge the slot). 
     Display  14  may include pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable pixel structures. A display cover layer such as a layer of clear glass or plastic may cover the surface of display  14  or the outermost layer of display  14  may be formed from a color filter layer, thin-film transistor layer, or other display layer. Buttons such as button  24  may pass through openings in the cover layer if desired. 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 with four edges, structures  16  may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (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 that helps hold display  14  to device  10 ). Peripheral structures  16  may, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, curved 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. 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 ). Peripheral housing structures  16  may have substantially straight vertical sidewalls, may have sidewalls that are 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 or wall. 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 sides of housing  12  may be formed as flat or curved 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 and/or may include multiple metal pieces that are assembled together to form housing  12 . The planar rear wall of housing  12  may have one or more, two or more, or three or more portions. Peripheral conductive housing structures  16  and/or the conductive rear wall of housing  12  may form one or more exterior surfaces of device  10  (e.g., surfaces that are visible to a user of device  10 ) and/or may be implemented using internal structures that do not form exterior surfaces of device  10  (e.g., conductive housing structures that are not visible to a user of device  10  such as conductive structures that are covered with layers such as thin cosmetic layers, protective coatings, and/or other coating layers that may include dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of device  10  and/or serve to hide structures  16  from view of the user). 
     Display  14  may have an array of pixels that form an active area AA that displays images for a user of device  10 . An inactive border region such as inactive area IA may run along one or more of the peripheral edges of active area AA. 
     Display  14  may include conductive structures such as an array of capacitive electrodes for a touch sensor, conductive lines for addressing pixels, driver circuits, etc. Housing  12  may include internal conductive structures such as metal frame members and a planar conductive housing member (sometimes referred to as a backplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more metal parts that is welded or otherwise connected between opposing sides of member  16 ). The backplate may form an exterior rear surface of device  10  or may be covered by layers such as thin cosmetic layers, protective coatings, and/or other coatings that may include dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of device  10  and/or serve to hide the backplate from view of the user. Device  10  may also include conductive structures such as printed circuit boards, components mounted on printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground plane in device  10 , may extend under active area AA of display  14 , for 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 ground structures such as conductive portions of housing  12 , conductive traces on a printed circuit board, conductive electrical components in display  14 , etc.). These openings, which may sometimes be referred to as gaps, may be filled with air, plastic, and/or other dielectrics and may be used in forming slot antenna resonating elements for one or more antennas in device  10 , if desired. 
     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 . If desired, the ground plane that is under active area AA of display  14  and/or other metal structures in device  10  may have portions that extend into parts of the ends of device  10  (e.g., the ground may extend towards the dielectric-filled openings in regions  20  and  22 ), thereby narrowing the slots 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 (e.g., at ends  20  and  22  of device  10  of  FIG. 1 ), 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 these locations. The arrangement of  FIG. 1  is merely illustrative. 
     Portions of peripheral housing structures  16  may be provided with peripheral gap structures. For example, peripheral conductive housing structures  16  may be provided with one or more peripheral 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 of gaps  18 ), three peripheral conductive segments (e.g., in an arrangement with three of gaps  18 ), four peripheral conductive segments (e.g., in an arrangement with four of gaps  18 , etc.). The segments of peripheral conductive housing structures  16  that are formed in this way may form parts of antennas in device  10 . 
     If desired, openings in housing  12  such as grooves that extend partway or completely through housing  12  may extend across the width of the rear wall of housing  12  and may penetrate through the rear wall of housing  12  to divide the rear wall into different portions. These grooves may also extend into peripheral housing structures  16  and may form antenna slots, gaps  18 , and other structures in device  10 . Polymer or other dielectric may fill these grooves and other housing openings. In some situations, housing openings that form antenna slots and other structure may be filled with a dielectric such as air. 
     In a typical scenario, device  10  may have one or more upper antennas and one or more 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 showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , 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 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, 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, multiple-input and multiple-output (MIMO) protocols, antenna diversity protocols, etc. 
     Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  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 devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  32  may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, position and orientation sensors (e.g., sensors such as accelerometers, gyroscopes, and compasses), capacitance sensors, proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors, etc.), fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button  24  of  FIG. 1  or a fingerprint sensor that takes the place of button  24 ), etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. 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, transmission lines, 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 radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . 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 frequency ranges such as a low communications band from 700 to 960 MHz, a low-midband from 960 to 1710 MHz, a midband from 1710 to 2170 MHz, a high band from 2300 to 2700 MHz, an ultra-high band from 3400 to 3700 MHz or other communications bands between 600 MHz and 4000 MHz or other suitable frequencies (as examples). 
     Circuitry  38  may handle voice data and non-voice data. 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 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment such as GPS receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. 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 structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, dipole antenna structures, monopole antenna structures, 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. 
     As shown in  FIG. 3 , transceiver circuitry  90  in wireless circuitry  34  may be coupled to antenna structures  40  using paths such as path  92 . Wireless circuitry  34  may be coupled to control circuitry  28 . Control circuitry  28  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures such as antenna(s)  40  with the ability to cover communications frequencies of interest, antenna(s)  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna(s)  40  may be provided with adjustable circuits such as tunable components  102  to tune antennas over communications bands of interest. Tunable components  102  may be part of a tunable filter or tunable impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and antenna ground, etc. 
     Tunable components  102  may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of device  10 , control circuitry  28  may issue control signals on one or more paths such as path  103  that adjust inductance values, capacitance values, or other parameters associated with tunable components  102 , thereby tuning antenna structures  40  to cover desired communications bands. 
     Path  92  may include one or more transmission lines. As an example, signal path  92  of  FIG. 3  may be a transmission line having a positive signal conductor such as line  94  and a ground signal conductor such as line  96 . Lines  94  and  96  may form parts of a coaxial cable, a stripline transmission line, or a microstrip transmission line (as examples). A matching network (e.g., an adjustable matching network formed using tunable components  102 ) may include components such as inductors, resistors, and capacitors used in matching the impedance of antenna(s)  40  to the impedance of transmission line  92 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna(s)  40  and may be tunable and/or fixed components. 
     Transmission line  92  may be coupled to antenna feed structures associated with antenna structures  40 . As an example, antenna structures  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed  112  with a positive antenna feed terminal such as terminal  98  and a ground antenna feed terminal such as ground antenna feed terminal  100 . Positive transmission line conductor  94  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  96  may be coupled to ground antenna feed terminal  100 . Other types of antenna feed arrangements may be used if desired. For example, antenna structures  40  may be fed using multiple feeds. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Control circuitry  28  may use information from a proximity sensor (see, e.g., sensors  32  of  FIG. 2 ), wireless performance metric data such as received signal strength information, device orientation information from an orientation sensor, device motion data from an accelerometer or other motion detecting sensor, information about a usage scenario of device  10 , information about whether audio is being played through speaker  26 , information from one or more antenna impedance sensors, and/or other information in determining when antenna(s)  40  is being affected by the presence of nearby external objects or is otherwise in need of tuning. In response, control circuitry  28  may adjust an adjustable inductor, adjustable capacitor, switch, or other tunable component  102  to ensure that antenna structures  40  operate as desired. Adjustments to component  102  may also be made to extend the coverage of antenna structures  40  (e.g., to cover desired communications bands that extend over a range of frequencies larger than antenna structures  40  would cover without tuning). 
     Antennas  40  may include slot antenna structures, inverted-F antenna structures (e.g., planar and non-planar inverted-F antenna structures), loop antenna structures, combinations of these, or other antenna structures. 
     An illustrative inverted-F antenna structure is shown in  FIG. 4 . As shown in  FIG. 4 , inverted-F antenna structure  40  (sometimes referred to herein as antenna  40  or inverted-F antenna  40 ) may include an inverted-F antenna resonating element such as antenna resonating element  106  and an antenna ground (ground plane) such as antenna ground  104 . Antenna resonating element  106  may have a main resonating element arm such as arm  108 . The length of arm  108  may be selected so that antenna structure  40  resonates at desired operating frequencies. For example, the length of arm  108  (or a branch of arm  108 ) may be a quarter of a wavelength at a desired operating frequency for antenna  40 . Antenna structure  40  may also exhibit resonances at harmonic frequencies. If desired, slot antenna structures or other antenna structures may be incorporated into an inverted-F antenna such as antenna  40  of  FIG. 4  (e.g., to enhance antenna response in one or more communications bands). As an example, a slot antenna structure may be formed between arm  108  or other portions of resonating element  106  and ground  104 . In these scenarios, antenna  40  may include both slot antenna and inverted-F antenna structures and may sometimes be referred to as a hybrid inverted-F and slot antenna. 
     Arm  108  may be separated from ground  104  by a dielectric-filled opening such as dielectric gap  101 . Antenna ground  104  may be formed from housing structures such as a conductive support plate, printed circuit traces, metal portions of electronic components, or other conductive ground structures. Gap  101  may be formed by air, plastic, and/or other dielectric materials. 
     Main resonating element arm  108  may be coupled to ground  104  by return path  110 . Antenna feed  112  may include positive antenna feed terminal  98  and ground antenna feed terminal  100  and may run parallel to return path  110  between arm  108  and ground  104 . If desired, inverted-F antenna structures such as illustrative antenna structure  40  of  FIG. 4  may have more than one resonating arm branch (e.g., to create multiple frequency resonances to support operations in multiple communications bands) or may have other antenna structures (e.g., parasitic antenna resonating elements, tunable components to support antenna tuning, etc.). Arm  108  may have other shapes and may follow any desired path if desired (e.g., paths having curved and/or straight segments). 
     If desired, antenna  40  may include one or more adjustable circuits (e.g., tunable components  102  of  FIG. 3 ) that are coupled to antenna resonating element structures  106  such as arm  108 . As shown in  FIG. 4 , for example, tunable components  102  such as adjustable inductor  114  may be coupled between antenna resonating element arm structures in antenna  40  such as arm  108  and antenna ground  104  (i.e., adjustable inductor  114  may bridge gap  101 ). Adjustable inductor  114  may exhibit an inductance value that is adjusted in response to control signals  116  provided to adjustable inductor  114  from control circuitry  28 . 
     A top interior view of an illustrative portion of device  10  that contains antennas is shown in  FIG. 5 . As shown in  FIG. 5 , device  10  may have peripheral conductive housing structures such as peripheral conductive housing structures  16 . Peripheral conductive housing structures  16  may be segmented by dielectric-filled gaps (e.g., plastic gaps)  18  such as gaps  18 - 1  and  18 - 2 . Antenna structures  40  may include multiple antennas such as antenna  40 F, antenna  40 W, and antenna  40 U. Antenna  40 F may be include a corresponding antenna resonating element and ground  104 . The resonating element may include an inverted-F antenna resonating element arm such as arm  108  that is formed from a length of peripheral conductive housing structures  16  between gaps  18 - 1  and  18 - 2 . Air and/or other dielectric may fill slot  101  between arm  108  and ground structures  104 . If desired, opening  101  may be configured to form a slot antenna resonating element structure that contributes to the overall performance of the antenna. Antenna ground  104  may be formed from conductive housing structures, from electrical device components in device  10 , from printed circuit board traces, from strips of conductor such as strips of wire and metal foil, conductive portions of display  14 , and/or other conductive structures. In one suitable arrangement ground  104  is formed from conductive portions of housing  12  (e.g., portions of a rear wall of housing  12  and portions of peripheral conductive housing structures  16  that are separated from arm  108  by peripheral gaps  18 ) and conductive portions of display  14  (e.g., conductive portions of a display panel, a conductive plate for supporting the display panel, and/or a conductive frame for supporting the conductive plate and/or the display panel). 
     Antenna  40 F may support a resonance in one or more desired frequency bands. The length of arm  108  may be selected to resonate in one or more desired frequency bands. For example, arm  108  may support a resonance in a cellular low band LB, midband MB, high band HB, and/or a satellite navigation band. In order to handle wireless communications at other frequencies (e.g., frequencies in the 2.4 GHz and/or 5 GHz wireless local area network band), an additional antenna such as antenna  40 W may be formed within region  206 . In order to handle wireless communications at still other frequencies (e.g., frequencies in the ultra-high band UHB) an additional antenna such as antenna  40 U may be formed within region  254 . 
     Ground  104  may serve as antenna ground for one or more antennas. For example, antenna  40 F may include an antenna ground formed from ground  104 . Antenna  40 W in region  252  may include a corresponding antenna resonating element and ground  104 . Ultra-high band antenna  40 U in region  254  may include a corresponding antenna resonating element and ground  104 . Inverted-F antenna (sometimes referred to as a cellular antenna)  40 F may be fed by a corresponding antenna feed such as feed  112  having positive feed terminal  98  coupled to arm  108  and ground feed terminal  100  coupled to ground  104 . Positive transmission line conductor  94  and ground transmission line conductor  96  may form a transmission line  92  that is coupled between cellular transceiver circuitry  38  and antenna feed  112 . Cellular transceiver circuitry  38  may handle wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a low-midband from 960 to 1710 MHz, a midband from 1710 to 2170 MHz, a high band from 2300 to 2700 MHz, and a ultra-high band from 3400 to 3700 MHz. Cellular transceiver circuitry  38  may handle wireless communications in the low band, low-midband, midband, and high band using transmission line  92 . 
     The cellular antenna may include an adjustable matching network (MN) such as adjustable matching circuitry  140  that is interposed in transmission line path  92 . Control circuitry  28  (as shown in  FIG. 2 ) may provide control signals to adjust matching circuitry  140  (e.g., to provide a selected matching impedance between transmission line  92  and antenna feed  112 ). Adjustable matching circuitry  140  may include inductors, resistors, capacitors, or other components. Matching network components may be provided as discrete components (e.g., surface mount technology components), may be embedded within a flexible printed circuit, or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. 
     Wireless local area network antenna  40 W (sometimes referred to as a WiFi® antenna) may contain an inverted-F antenna resonating element or other suitable resonating element. The wireless local area network antenna may be fed by a corresponding feed  220  having positive antenna feed terminal  222  coupled to the antenna resonating element and ground antenna feed terminal  224  coupled to ground  104 . Feed  220  of the wireless local area network antenna may handle radio-frequency signals conveyed using positive signal conductor  226  and ground signal conductor  228  of transmission line  232 . Transmission line  232  may be a coaxial cable, a stripline transmission line, or a microstrip transmission line (as examples). 
     Wireless local area network antenna  40 W may resonate in multiple bands. For example, the antenna formed in region  230  may serve 2.4 GHz (e.g., between 2400 MHz and 2500 MHz) and 5 GHz (e.g., between 5150 MHz and 5850 MHz) bands for WiFi® (IEEE 802.11) communications. Transmission line  232  is coupled between wireless local area network transceiver circuitry  36  and feed  220 . Wireless local area network transceiver circuitry  36  may handle wireless local area network band communications using transmission line  232  and feed  220 . 
     Ultra-high band antenna  40 U may contain an inverted-F antenna resonating element or other suitable resonating element. The ultra-high band antenna may be fed using feed  266  having positive antenna feed terminal  262  coupled to the corresponding antenna resonating element and ground antenna feed terminal  264  coupled to ground  104 . Feed  266  of the ultra-high band antenna may handle radio-frequency signals conveyed using positive signal conductor  268  and ground signal conductor  270  of transmission line  272 . Transmission line  272  may be a coaxial cable, a stripline transmission line, or a microstrip transmission line (as examples). 
     Ultra-high band antenna  40 U may resonate in one or more frequency bands. For example, the ultra-high band antenna may resonate in the ultra-high band (e.g., 3400 MHz-3700 MHz). Transmission line  272  is coupled between cellular transceiver circuitry  38  and feed  266 . Cellular transceiver circuitry  38  may handle wireless communications in the ultra-high band using transmission line  272  and feed  266 . 
     Ground plane  104  may have any desired shape within device  10 . For example, ground plane  104  may align with gap  18 - 1  in peripheral conductive hosing structures  16  (e.g., the lower edge of gap  18 - 1  may be aligned with the edge of ground plane  104  defining slot  101  adjacent to gap  18 - 1  such that the lower edge of gap  18 - 1  is approximately collinear with the edge of ground plane  104  at the interface between ground plane  104  and the portion of peripheral conductive structures  16  adjacent to gap  18 - 1 ). This example is merely illustrative. In the embodiment of  FIG. 5 , ground  104  includes a vertical slot adjacent to gap  18 - 1  that extends above gap  18 - 1  (e.g., along the Y-axis of  FIG. 5 ) and a vertical slot adjacent to gap  18 - 2  that extends above gap  18 - 2 . 
     If desired, ground plane  104  may include a vertical slot  162  adjacent to gap  18 - 1  that extends beyond the upper edge (e.g., upper edge  174 ) of gap  18 - 1  (e.g., in the direction of the Y-axis of  FIG. 5 ). Slot  162  may, for example, have two edges that are defined by ground  104  and one edge that is defined by peripheral conductive structures  16 . Slot  162  may have an open end defined by an open end of slot  101  at gap  18 - 1 . Slot  162  may have a width  176  that separates ground  104  from the portion of peripheral conductive structures  16  above gap  18 - 1  (e.g., in the direction of the X-axis of  FIG. 5 ). Because the portion of peripheral conductive structures  16  above gap  18 - 1  is shorted to ground  104  (and thus forms part of the antenna ground for antenna structures  40 ), slot  162  may effectively form an open slot having three sides defined by the antenna ground for antenna structures  40 . Slot  162  may have any desired width (e.g., about 2 mm, less than 4 mm, less than 3 mm, less than 2 mm, less than 1 mm, more than 0.5 mm, more than 1.5 mm, more than 2.5 mm, 1-3 mm, etc.). Slot  162  may have an elongated length  178  (e.g., perpendicular to width  176 ). Slot  162  may have any desired length (e.g., 10-15 mm, more than 5 mm, more than 10 mm, more than 15 mm, more than 30 mm, less than 30 mm, less than 20 mm, less than 15 mm, less than 10 mm, between 5 and 20 mm, etc.). 
     Electronic device  10  may be characterized by longitudinal axis  282 . Length  178  may extend parallel to longitudinal axis  282  (e.g., the Y-axis of  FIG. 5 ). Portions of slot  162  may contribute slot antenna resonances to antenna  40  in one or more frequency bands if desired. For example, the length and width of slot  162  may be selected so that antenna  40  resonates at desired operating frequencies. If desired, the overall length of slots  101  and  162  may be selected so that antenna  40  resonates at desired operating frequencies. 
     If desired, ground plane  104  may include an additional vertical slot  182  adjacent to gap  18 - 2  that extends beyond the upper edge (e.g., upper edge  184 ) of gap  18 - 2  (e.g., in the direction of the Y-axis of  FIG. 5 ). Slot  182  may, for example, have two edges that are defined by ground  104  and one edge that is defined by peripheral conductive structures  16 . Slot  182  may have an open end defined by an open end of slot  101  at gap  18 - 2 . Slot  182  may have a width  186  that separates ground  104  from the portion of peripheral conductive structures  16  above gap  18 - 1  (e.g., in the direction of the X-axis of  FIG. 5 ). Because the portion of peripheral conductive structures  16  above gap  18 - 2  is shorted to ground  104  (and thus forms part of the antenna ground for antenna structures  40 ), slot  182  may effectively form an open slot having three sides defined by the antenna ground for antenna structures  40 . Slot  182  may have any desired width (e.g., about 2 mm, less than 4 mm, less than 3 mm, less than 2 mm, less than 1 mm, more than 0.5 mm, more than 1.5 mm, more than 2.5 mm, 1-3 mm, etc.). Slot  182  may have an elongated length  188  (e.g., perpendicular to width  186 ). Slot  182  may have any desired length (e.g., 10-15 mm, more than 5 mm, more than 10 mm, more than 15 mm, more than 30 mm, less than 30 mm, less than 20 mm, less than 15 mm, less than 10 mm, between 5 and 20 mm, etc.). 
     Length  188  may extend parallel to longitudinal axis  282  (e.g., the Y-axis of  FIG. 5 ). Portions of slot  182  may contribute slot antenna resonances to antenna  40  in one or more frequency bands if desired. For example, the length and width of slot  182  may be selected so that antenna  40  resonates at desired operating frequencies. If desired, the overall length of slots  101  and  182  may be selected so that antenna  40  resonates at desired operating frequencies. If desired, the overall length of slots  101 ,  162 , and  182  may be selected so that antenna  40  resonates at desired operating frequencies. 
     A return path such as path  110  of  FIG. 4  may be formed by a fixed conductive path bridging slot  101  or one or more adjustable components such as adjustable components  202  and/or  208  (see, e.g., adjustable components such as tuning components  102  of  FIG. 3 ). Adjustable components  202  and  208  may sometimes be referred to herein as tuning components, tunable components, tuning circuits, tunable circuits, adjustable components, or adjustable tuning components. 
     Adjustable component  202  may bridge slot  101  at a first location along slot  101  (e.g., component  202  may be coupled between terminal  206  on ground plane  104  and terminal  204  on peripheral conductive structures  16 ). Adjustable component  208  may bridge slot  101  at a second location along slot  101  (e.g., component  208  may be coupled between terminal  212  on ground plane  104  and terminal  210  on peripheral conductive structures  16 ). Ground antenna feed terminal  100  may be interposed between terminal  206  and terminal  212  on ground plane  104 . Positive antenna feed terminal  98  may be interposed between terminal  204  and terminal  210  on peripheral conductive structures  16 . Terminal  212  may be closer to ground antenna feed terminal  100  than terminal  206 . Terminal  210  may be closer to positive antenna feed terminal  98  than terminal  204 . 
     Components  202  and  208  may include switches coupled to fixed components such as inductors for providing adjustable amounts of inductance or an open circuit between ground  104  and peripheral conductive structures  16 . Components  202  and  208  may also include fixed components that are not coupled to switches or a combination of components that are coupled to switches and components that are not coupled to switches. These examples are merely illustrative and, in general, components  202  and  208  may include other components such as adjustable return path switches, switches coupled to capacitors, or any other desired components (e.g., resistors, capacitors, inductors, and/or inductors arranged in any desired manner). 
     Components  202  and  208  may be adjusted based on the operating environment of the electronic device. For example, a tuning mode may be selected based on the presence or absence of external objects such as a user&#39;s hand or other body part in the vicinity of antenna structures  40  and/or based on required communication bands. Components  202  and  208  provide the cellular antenna with flexibility to accommodate different loading conditions (e.g., different loading conditions that may arise due to the presence of a user&#39;s hand or other external object on various different portions of device  10  adjacent to various different corresponding portions of antenna structures  40 ). 
     Components  202  and  208  may be formed between peripheral conductive housing structures  16  and ground plane  104  using any desired structures. For example, components  202  and  208  may each be formed on a printed circuit such as a flexible printed circuit board that is coupled between peripheral conductive housing structures  16  and ground plane  104 . 
     The frequency response of antenna  40 F may be dependent upon the tuning mode of adjustable components  202  and  208 . For example, in a first tuning mode, adjustable component  202  may form an open circuit between antenna resonating element arm  108  and antenna ground  104 , whereas adjustable component  208  may selectively couple one or more inductors between antenna resonating element arm  108  and antenna ground  104  to tune antenna  40 F. In the first tuning mode, the resonance of antenna  40  in low band LB (e.g., from 700 MHz to 960 MHz or another suitable frequency range) may be associated with the distance along peripheral conductive structures  16  between feed  112  of  FIG. 5  and gap  18 - 1 , for example.  FIG. 5  is a view from the front of device  10 , so gap  18 - 1  of  FIG. 5  lies on the left edge of device  10  when device  10  is viewed from the front (e.g., the side of device  10  on which display  14  is formed) and lies on the right edge of device  10  when device  10  is viewed from behind. The resonance of antenna  40  at midband MB (e.g., from 1710 MHz to 2170 MHz) may be associated with the distance along peripheral conductive structures  16  between feed  112  and gap  18 - 2 , for example. Antenna performance in midband MB may also be supported by slot  182  in ground plane  104 . Antenna performance in high band HB (e.g., 2300 MHz to 2700 MHz) may be supported by slot  162  in ground plane  104  and/or by a harmonic mode of a resonance supported by antenna arm  108 . 
     In a second tuning mode, adjustable component  208  may form an open circuit between antenna resonating element arm  108  and antenna ground  104  to tune the antenna, whereas adjustable component  202  may selectively couple one or more inductors between antenna resonating element arm  108  and antenna ground  104  to tune antenna  40 F. In the second tuning mode, the resonance of antenna  40 F in low band LB may be associated with the distance along peripheral conductive structures  16  between the position of component  202  (i.e., terminal  204 ) of  FIG. 5  and gap  18 - 2 , for example. The resonance of antenna  40  in midband MB may be associated with the distance along peripheral conductive structures  16  between the position of component  202  (i.e., terminal  204 ) and gap  18 - 1 , for example. Antenna performance in high band HB may also be supported by slot  162  in ground plane  104 . 
     In a third tuning mode, adjustable components  202  and  208  may both selectively couple one or more inductors between antenna resonating element arm  108  and antenna ground  104  to tune antenna  40 F. In the third tuning mode, the resonance of antenna  40  at midband MB and high band HB may be associated with a loop including portions of peripheral conductive structures  16  (e.g., the portion of peripheral conductive structures  16  between terminal  204  of component  202  and terminal  210  of component  208 ) component  202 , ground plane  104 , and component  208 . 
       FIG. 6  is a top view of the illustrative antenna structures of  FIG. 5  showing how a single printed circuit may be used to feed and control multiple antennas such as antennas  40 W,  40 U, and  40 F. As shown in  FIG. 6 , numerous components, transmission lines, and digital signal lines may be formed on flexible printed circuit  302 . Flexible printed circuit  302  may be formed from one or more sheets of polyimide or other flexible polymer layer. Flexible printed circuit  302  may be connected to a substrate such as printed circuit  304  by connector  306 . Printed circuit  304  may, for example, be a printed circuit on which one or more of transceivers  90  and/or some or all of storage and processing circuitry  28  are mounted. Printed circuit  304  may be a rigid printed circuit board (e.g., a printed circuit board formed from fiberglass-filled epoxy or other rigid printed circuit board material) or may be a flexible printed circuit (e.g., a flexible printed circuit formed from a sheet of polyimide or other flexible polymer layer). In some embodiments, printed circuit  304  may be the motherboard for electronic device  10  (printed circuit  304  may sometimes be referred to as motherboard  304  or main logic board  304 ). Connector  306  may include multiple conductive contacts. For example, connector  306  may include multiple radio-frequency contacts for conveying radio-frequency signals to antenna feeds associated with antennas  40 U,  40 F, and  40 W as well as conductive contacts for conveying control signals that control the operation (e.g., tuning) of antennas  40 U,  40 F, and  40 W. 
     Transmission line  232  for wireless local area network antenna  40 W may be formed on flexible printed circuit  302 . Transmission line  232  may be embedded within and/or formed from conductive material on a surface of flexible printed circuit  302 . Additional components of wireless local area network antenna  40 W may be formed on flexible printed circuit  302 . For example, the antenna resonating element of wireless local area network antenna  40 W may be formed from traces on flexible printed circuit  302  or from traces on an additional printed circuit coupled to flexible printed circuit  302 . In some suitable arrangements, wireless local area network antenna  40 W may include a return path from the antenna resonating element to ground  104 . The return path may also be formed at least partially from traces on flexible printed circuit  302 , if desired. 
     Transmission line  272  for ultra-high band antenna  40 U may be formed on flexible printed circuit  302 . Transmission line  272  may be embedded within and/or formed from conductive material on a surface of flexible printed circuit  302 . Additional components of ultra-high band antenna  40 U may be formed on flexible printed circuit  302 . For example, the antenna resonating element of ultra-high band antenna  40 U may be formed from traces on flexible printed circuit  302  or from traces on an additional printed circuit coupled to flexible printed circuit  302 . In some suitable arrangements, ultra-high band antenna  40 U may include a return path from the antenna resonating element to ground. The return path may also be formed at least partially from traces on flexible printed circuit  302 , if desired. 
     Transmission line  92  for cellular antenna  40 F may be formed on flexible printed circuit  302 . Transmission line  92  may be embedded within and/or formed from conductive material on a surface of flexible printed circuit  302 . Additional components of the cellular antenna may be formed on flexible printed circuit  302 . For example, the cellular antenna may include a return path that couples antenna resonating element  108  to ground. The return path may be formed at least partially from traces on flexible printed circuit  302  if desired. 
     As shown in  FIGS. 5 and 6 , an adjustable matching network such as adjustable matching circuitry  140  may be interposed in transmission line path  92 . Matching circuitry  140  may include any desired components. In the example of  FIG. 6 , matching circuitry  140  is shown as including an inductor  308 , a capacitor  310 , and a resistor  312 . Inductor  308 , capacitor  310 , and resistor  312  may be fixed components or may be adjustable components. In embodiments where adjustable components are used, one or more switches may be included in matching circuitry  140 . The example of  FIG. 6  is merely illustrative and matching circuitry  140  may include any desired number of fixed and adjustable components. 
     Matching circuitry  140  (including inductor  308 , capacitor  310 , resistor  312 , and any corresponding switching circuitry) may be formed on flexible printed circuit  302 . Each component may be a surface mount technology component that is mounted on a surface of flexible printed circuit  302 . In other embodiments, some or all of components  308 ,  310 , and  312  may be embedded components that are embedded within flexible printed circuit  302  (e.g., distributed capacitances and/or inductances within printed circuit  302 ). 
     As previously discussed in connection with  FIG. 5 , electronic device  10  may include one or more adjustable components such as adjustable components  202  and  208 . Components  202  and  208  may be adjusted based on the operating environment of the electronic device to accommodate different loading conditions (e.g., different loading conditions that may arise due to the presence of a user&#39;s hand or other external object on various different portions of device  10  adjacent to various different corresponding portions of antenna structures  40 ). Components  202  and  208  may also form part of a return path for the cellular antenna. 
     In  FIG. 6 , adjustable component  202  includes an inductor  314  and a switch  316 , and adjustable component  208  includes an inductor  320  and a switch  318 . Switch  316  may be used to optionally connect inductor  314  between peripheral conductive housing structure  16  and ground  104 . For example, when switch  316  is in a first position (i.e., a closed position), inductor  314  may be connected between peripheral conductive housing structure  16  and ground  104  (i.e., between terminals  204  and  206  in  FIG. 5 ). When switch  316  is in a second position (i.e., an open position), inductor  314  may not be connected between peripheral conductive housing structure  16  and ground  104 . Similarly switch  318  may be used to optionally connect inductor  320  between peripheral conductive housing structure  16  and ground  104 . For example, when switch  318  is in a first position (i.e., a closed position), inductor  320  may be connected between peripheral conductive housing structure  16  and ground  104  (i.e., between terminals  210  and  212  in  FIG. 5 ). When switch  318  is in a second position (i.e., an open position), inductor  320  may not be connected between peripheral conductive housing structure  16  and ground  104 . 
     Adjustable components  202  and  208  (e.g., inductors  314  and  320  and switches  316  and  318 ) may be formed on flexible printed circuit  302 . Each inductor may be a surface mount technology component that is mounted on a surface of flexible printed circuit  302 . In other embodiments, one or both of inductors  314  and  320  may be embedded components that are embedded within flexible printed circuit  302  (e.g., distributed capacitances and inductances within printed circuit  302 ). Switches  316  and  318  may be mounted on flexible printed circuit  302  or may be embedded within flexible printed circuit  302 . 
     Flexible printed circuit  302  may include control lines for controlling the state of adjustable component  202 , adjustable component  208 , matching network  140 , and/or other tuning components  102  ( FIG. 3 ). For example, flexible printed circuit  302  may include control lines such as digital (control) signal lines  324  that are used to control components within electronic device  10 . One or more digital signal lines may be provided to matching circuitry  140  to control the components of matching circuitry  140 . For example, the digital signal lines may provide control signals to control the switches or other components within the adjustable matching circuitry. Digital signal lines  324  may also provide signals to adjustable components such as adjustable component  202  or adjustable component  208 . For example, a digital signal line may provide a control signal for switch  316  of adjustable component  202 . A digital signal line may also send or receive signals from a component such as inductor  314  of adjustable component  202 . This is merely illustrative and, if desired, analog control signals or other control signals may be used. 
     Thus far, flexible printed circuit  302  has been described as including components related to antenna structures  40  (e.g., radio-frequency transmission lines, matching circuitry, traces for antenna resonating elements or return paths, fixed or adjustable components for tuning an antenna, digital control lines for controlling antenna-tuning components, etc.). However, other components (e.g., components not associated with conveying radio-frequency signals using antenna structures  40 ) may also be formed on flexible printed circuit  302  if desired. As shown in  FIG. 6 , an additional electrical component  326  (e.g., a component not associated with conveying radio-frequency signals using antenna structures  40 ) may be formed on flexible printed circuit  302 . Electrical component  326  may be, for example, an input-output component or a portion of an input-output component (e.g., input-output devices  32  of  FIG. 2 ) such as a button, camera, microphone, speaker, status indicator, light source, light sensor, position and orientation sensor (e.g., an accelerometer, gyroscope, compass, etc.), capacitance sensor, proximity sensor (e.g., capacitive proximity sensor, light-based proximity sensors, etc.), fingerprint sensor, or any other desired input-output component. One or more digital signal lines may provide control signals to electrical component  326  or may send and/or receive data (e.g., sensor data) to and/or from electrical component  326 . Multiple components  326  may be supported by flexible printed circuit  302  if desired. 
     The conductive lines on flexible printed circuit  302  may be coupled to printed circuit  304  using a single connector (e.g., connector  306 ). For example, connector  306  may couple each of transmission lines  92 ,  272 , and  232  as well as each of control lines  324  to main logic board  304 . 
     Flexible printed circuit  302  may be coupled to ground plane  104  at various points along the flexible printed circuit. Ground terminals  322  may be formed by fasteners such as screws or other conductive structures (e.g., a bracket, clip, spring, pin, screw, solder, weld, conductive adhesive, wire, metal strip, or a combination of these). The ground terminals may include structures to electrically connect and/or physically secure the flexible printed circuit to the ground plane. The flexible printed circuit may be coupled to any desired portions of ground  104 . 
     At each ground terminal within the device (e.g., terminals  322 ,  224 ,  264 , and/or  100 ), different components of the device ground (e.g., ground  104  in  FIG. 5 ) may be electrically connected so that the conductive structures that are located the closest to resonating element arm  108  are held at a ground potential and form a part of antenna ground  104 . In one suitable arrangement, ground  104  includes both conductive portions of housing  12  (e.g., portions of a rear wall of housing  12  such as a conductive backplate and portions of peripheral conductive housing structures  16  that are separated from arm  108  by peripheral gaps  18 ) as well as conductive portions of display  14  (e.g., conductive portions of a display panel, a conductive plate for supporting the display panel, and/or a conductive frame for supporting the conductive plate and/or the display panel). Vertical conductive structures (e.g., a bracket, clip, spring, pin, screw, solder, weld, conductive adhesive, wire, metal strip, or a combination of these) may couple conductive portions of housing  12  (e.g., a conductive backplate) to conductive portions of display  14  at terminals  322 ,  224 ,  264 , and/or  100 . Ensuring that the conductive structures closest to resonating element arm  108  such as conductive portions of display  14  are held at a ground potential may, for example, serve to optimize the antenna efficiency of antenna structures  40 . 
     In one suitable arrangement, ground terminals  322  of  FIG. 6  may include screws that secure and electrically connect flexible printed circuit  302  to the conductive backplate. Ground terminals  322  may also include an additional conductive structure such as a spring that electrically connects the screw and the conductive backplate to the conductive display portion that forms an additional portion of the device ground. 
     Flexible printed circuit  302  may include a first portion (e.g., portion  328 ) that extends parallel to the Y-axis and a second portion (e.g., portion  330 ) that extends parallel to the X-axis. This example is merely illustrative, and flexible printed circuit  302  may have any desired shape. 
       FIG. 7  is a top view of portion  328  of flexible printed circuit  302  (e.g., a view of the top surface of printed circuit  302  or a cross-sectional view of components within printed circuit  302 ). In the example of  FIG. 7 , flexible printed circuit  302  extends along longitudinal axis  332  (which may be parallel to the Y-axis). Other layouts may be used for flexible printed circuit  302  if desired. The example of  FIG. 7  is merely illustrative. 
     As shown in  FIG. 7 , flexible printed circuit  302  may have multiple metal signal traces such as transmission lines  232 ,  92 , and  272  and control lines  324  such as digital signal line  324 - 1 , digital signal line  324 - 2 , and digital signal line  324 - 3 . The transmission line traces and digital signal lines may run parallel to longitudinal axis  332  in portion  328  of the flexible printed circuit (e.g., transmission lines  232 ,  92 , and  272  and digital signal lines  324  may extend along a longitudinal axis that runs parallel to longitudinal axis  332 ). 
     Flexible printed circuit  302  may have ground structures such as multiple grounded layers that are coupled together by vertically extending conductive structures such as through vias  334 . Vias  334  may extend vertically in dimension Z to couple respective ground layers together or to otherwise short together metal traces within flexible printed circuit  302 . Vias  334  may divide the signal lines into sets or groups of signal lines such as set S 1 , set S 2 , set S 3 , and set S 4 . There are four sets of signal lines in the example of  FIG. 7 , separated by three respective columns or fences of vias  334 . Other numbers of sets of signal traces may be used in flexible printed circuit  302  if desired. Signal lines may be assigned to the different sets of signal lines in a way that minimizes interference. 
     Signal interference can be minimized by arranging vias  334  in a pattern that forms grounded edges on both sides of each set of signal lines. For example, a series of vias may run along left edge  302 L of flexible printed circuit  302  parallel to dimension Y and a series of vias may run along right edge  302 R of flexible printed circuit  302  parallel to dimension Y. Additional vias  334  may run parallel to dimension Y between sets of signal lines. In this way, set S 1  of signal lines is electromagnetically isolated from interference by a left-hand ground path formed from vias  334  on the left edge  302 L of the flexible printed circuit and a right-hand ground path formed from vias  334  between set S 1  and set S 2 . Other sets of signal lines are likewise bordered by grounding structures that run along their right and left edges. By forming grounding vias on the left and right edges of flexible printed circuit  302  and between each set of signal lines within flexible printed circuit  302 , interference between signals on different sets of signal lines and external signal interference may be reduced. 
     Vias  334  may be separated by a distance  336  in the Y-direction. Distance  336  (e.g., the pitch of vias  334 ) may be any desired distance (e.g., between 1 and 10 millimeters, between 1 and 20 millimeters, between 0.5 and 5 millimeters, between 4 and 6 millimeters, greater than 1 millimeter, greater than 3 millimeters, greater than 5 millimeters, less than 20 millimeters, less than 10 millimeters, less than 5 millimeters, less than 3 millimeters, less than 1 millimeter, etc.). In one suitable arrangement, pitch  336  may be less than or equal to approximately one-fifth of the wavelength of operation of the adjacent transmission line in order to provide satisfactory electromagnetic shielding with the adjacent conductive lines on printed circuit  302 . The spacing of the vias in the Y-direction in  FIG. 7  is shown as being the same between each set of signal lines. This example, however, is merely illustrative. The vias may be spaced by different amounts between different sets of signal lines if desired. 
     As shown in the cross-sectional side view of  FIG. 8  (e.g., as taken along line  382  in  FIG. 7 ), flexible printed circuit  302  may have ground layers such as layers G 1  and G 2  (e.g., ground layers formed from copper or other metal) and a signal layer that includes metal traces or lines for transmission lines  232 ,  92 , and  272  and digital control signal paths  324 . The signal lines may lie above lower ground layer G 2  and below upper ground layer G 1 . One or both of ground layers G 1  and G 2  and/or additional ground layers may be formed in flexible printed circuit  302  if desired. These conductive structures may be supported by substrate layers such as dielectric layers  338  (e.g., multiple layers of polyimide or other flexible polymer layers that make up the polymer substrate for flexible printed circuit  302 ). 
     Each of the radio-frequency transmission lines in  FIG. 8  can be formed using any desired radio-frequency transmission line structures (e.g., coplanar waveguides, coaxial cables or other coaxial structures, a stripline transmission line, a microstrip transmission line, etc.). Each radio-frequency transmission line may include more than one conductive trace such as signal traces for forming the corresponding positive signal conductor (e.g., positive signal conductor  94 ,  226 , or  268  in  FIG. 5 ) and ground traces for forming the corresponding ground signal conductor (e.g., ground signal conductor  96 ,  228 , or  270  in  FIG. 5 ). In some arrangements, ground layer G 1  and/or ground layer G 2  may form the ground signal conductor of one or more transmission lines and metal traces between ground layers G 1  and G 2  may form the positive signal conductor of the one or more transmission lines. 
     As shown in  FIG. 8 , there may be a number of stacked digital signal lines formed in set S 3  of signal lines in flexible printed circuit  302 . In the embodiment of  FIG. 8  there are nine digital signal lines formed in set S 3 . Digital signal line  324 - 1  may be stacked over digital signal line  324 - 4  and digital signal line  324 - 5 . Digital signal lines  324 - 2  and  324 - 3  may also be stacked over two other respective digital signal lines. This example is merely illustrative and any number of digital signal lines may be formed in set S 3  with any desired stacking arrangement. 
     In the embodiment of  FIG. 8 , a number of digital signal lines are stacked together in set S 3 , whereas transmission lines  232 ,  92 , and  272  are each the only signal lines in their respective sets. This arrangement may help mitigate interference between signals on different sets of signal lines. However, other arrangements may be used (e.g., other signal lines may be included with transmission lines  232 ,  92 , and  272  or only one digital signal line may be included in a set). 
     Vias  334  may be separated by a distance  340  in the X-direction. Distance  340  may be any desired distance (e.g., between 50 and 1000 microns, between 10 and 1000 microns, between 50 and 150 microns, between 25 and 500 microns, between 1 millimeter and 3 millimeters, greater than 10 microns, greater than 50 microns, greater than 100 microns, greater than 500 microns, less than 1 millimeter, less than 500 microns, less than 100 microns, less than 50 microns, etc.). The spacing of the vias in the X-direction in  FIG. 8  is shown as being the same between each set of signal lines. This example, however, is merely illustrative. The vias may be spaced by different amounts between different sets of signal lines if desired. 
     As shown in  FIG. 9 , flexible printed circuit  302  may be provided with variable thicknesses. For example, flexible printed circuit  302  may be characterized by a thickness T extending between upper surface  302 T and opposing lower surface  302 B of flexible printed circuit  302 . The thickness T of flexible printed circuit  302  may be locally thinned in certain areas (e.g., to enhance flexibility in flexible printed circuit  302  in those areas, to minimize occupied volume within electronic device  10  in those areas, etc.). As shown in  FIG. 9 , flexible printed circuit  302  may have thicknesses  342 ,  344 ,  346 , and  348  in different regions of the flexible printed circuit. Thickness  346  may be less than thickness  344  which may be less than thickness  342 . Thickness  348  may be greater than thicknesses  344  and  346  and may be the same as thickness  342 . In general, each portion of flexible printed circuit  302  may have any desired thickness. 
     As previously mentioned, reduced thickness portions of flexible printed circuit  302  may increase flexibility of the flexible printed circuit  302  (which may allow the flexible printed circuit to be bent). Other modifications to the flexible printed circuit may be made to promote bending in certain regions. For example, the width of the flexible printed circuit may be narrowed or slits may be made in the flexible printed circuit to promote bending. 
     In this way, a single flexible printed circuit may be used to both feed one or more antennas (e.g., antennas  40 F,  40 W, and  40 U) and to control the tuning of the antennas. The single flexible printed circuit may also support other adjacent components while also ensuring that the signal lines are electromagnetically isolated from each other to mitigate any interference between the radio-frequency transmission lines and the control signal lines. Using the single flexible printed circuit also minimizes space consumption within the electronic device. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170911
Publication Date: 20190730
Grant Date: 20190730
Priority Date: 20170911
Inventors: ZHOU, YIJUN
WANG, Yiren
EDWARDS, JENNIFER M.
XU, HAO
TSAI, MING-JU
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K1/189", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0215", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/09609", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0213", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/053", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/0053", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/165", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/09609", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/053", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0215", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0215", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/0458", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/09609", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K2201/053", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/189", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/165", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/165", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0213", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/12", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B7/02", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/0053", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 65631701