PATENT DOCUMENT

Publication Number: US-10847901-B1
Application Number: US-201916446503-A
Country: US
Kind Code: B1

Title: Electronic device antennas having isolation elements

Abstract:
An electronic device may include an antenna and peripheral conductive housing structures. A dielectric gap may divide the peripheral conductive housing structures into first and second segments. The first and second segments may be separated from the antenna ground by respective first and second slots and may be fed using respective first and second feeds. An antenna isolation element may be coupled to the antenna ground and may separate the first slot element from the second slot element. The antenna isolation element may include a metal strip having an end coupled to the antenna ground and an opposing tip that extends into the dielectric gap. The antenna isolation element may electromagnetically isolate first radio-frequency signals conveyed by the first antenna feed in a cellular midband from second radio-frequency signals conveyed by the second antenna feed in a cellular high band.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 ground structures; 
 a housing having peripheral conductive housing structures; 
 a dielectric gap that divides the peripheral conductive housing structures into first and second segments, the first segment being separated from the ground structures by a first slot element and the second segment being separated from the ground structures by a second slot element; 
 a first positive antenna feed terminal coupled to the first segment, the first positive antenna feed terminal and the first segment being configured to convey first radio-frequency signals in a first frequency band; 
 a second positive antenna feed terminal coupled to the second segment, the second positive antenna feed terminal and the second slot element being configured to convey second radio-frequency signals in a second frequency band that is different from the first frequency band; and 
 an isolation element that is coupled to the ground structures and that separates the first slot element from the second slot element, wherein the isolation element is configured to isolate the first radio-frequency signals in the first frequency band from the second radio-frequency signals in the second frequency band. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the second positive antenna feed terminal is configured to convey antenna currents in the second frequency band, the antenna currents being configured to flow from the second segment to the antenna ground across a portion of the dielectric gap and through the isolation element. 
     
     
       3. The electronic device defined in  claim 2 , wherein the isolation element is configured to form an open circuit impedance across the dielectric gap in the first frequency band. 
     
     
       4. The electronic device defined in  claim 1 , wherein the isolation element comprises a metal strip having a tip within the dielectric gap, the tip being interposed between the first and second segments. 
     
     
       5. The electronic device defined in  claim 4 , further comprising:
 a dielectric, wherein the metal strip comprises a conductive trace on the dielectric. 
 
     
     
       6. The electronic device defined in  claim 5 , wherein the dielectric fills the first and second slot elements and the dielectric gap. 
     
     
       7. The electronic device defined in  claim 4 , further comprising:
 a dielectric, wherein the metal strip is embedded in the dielectric. 
 
     
     
       8. The electronic device defined in  claim 1 , further comprising:
 a first adjustable component coupled between the first segment and the ground structures across the first slot element, the first adjustable component being configured to tune the first frequency band; and 
 a second adjustable component coupled between the second segment and the ground structures across the second slot element, the second adjustable component being configured to tune the second frequency band. 
 
     
     
       9. The electronic device defined in  claim 1 , wherein the second frequency band is higher than the first frequency band and the second slot element is further configured to convey the second radio-frequency signals in a third frequency band that is higher than the second frequency band. 
     
     
       10. The electronic device defined in  claim 9 , wherein the first segment is further configured to convey the first radio-frequency signals in a fourth frequency band that is lower than the first frequency band. 
     
     
       11. The electronic device defined in  claim 10 , wherein the first frequency band comprises a frequency between 1710 MHz and 2170 MHz, the second frequency band comprises a frequency between 2300 MHz and 2700 MHz, the third frequency band comprises a frequency between 3300 MHz and 5000 MHz, and the fourth frequency band comprises a frequency between 600 MHz and 960 MHz. 
     
     
       12. The electronic device defined in  claim 1 , wherein the second slot element is configured to convey the second radio-frequency signals while the first segment conveys the first radio-frequency signals. 
     
     
       13. An electronic device comprising:
 an antenna ground; 
 peripheral conductive housing structures; 
 a dielectric gap in the peripheral conductive housing structures, wherein the dielectric gap separates a first segment of the peripheral conductive housing structures from a second segment of the peripheral conductive housing structures; 
 a first slot element between the first segment and the antenna ground; 
 a second slot element between the second segment and the antenna ground; 
 a first antenna feed coupled across the first slot element; 
 a second antenna feed coupled across the second slot element; and 
 a metal strip having an end and a tip, wherein the end is coupled to the antenna ground and the tip is located within the dielectric gap and interposed between the first and second segments. 
 
     
     
       14. The electronic device defined in  claim 13 , wherein the first segment and the first antenna feed are configured to convey first radio-frequency signals in a first frequency band, the second slot element and the second antenna feed being configured to convey second radio-frequency signals in a second frequency band that is higher than the first frequency band. 
     
     
       15. The electronic device define din  claim 14 , wherein antenna currents corresponding to the second radio-frequency signals flow along a loop path that runs around the second slot element and that includes a portion of the antenna ground, the second segment, and the metal strip. 
     
     
       16. The electronic device defined in  claim 15 , wherein the antenna currents flow from the second segment to the tip across a portion of the dielectric gap and from the tip to the antenna ground through the metal strip. 
     
     
       17. The electronic device defined in  claim 16 , wherein the tip extends into the dielectric gap by a first distance with respect to an interior surface of the first segment, the tip is separated from the second segment by a second distance, and the first and second distances are selected to interpose a tuning capacitance on the loop path that tunes a frequency response of the second slot element. 
     
     
       18. The electronic device defined in  claim 17 , wherein the metal strip is configured to form an open circuit impedance between the tip and the first segment in the first frequency band. 
     
     
       19. An antenna comprising:
 ground structures; 
 a first conductive segment that is separated from the ground structures by a first slot element; 
 a second conductive segment that is separated from the ground structures by a second slot element and that is separated from the first conductive segment by a dielectric gap; 
 a metal strip having a first end coupled to the ground structures and an opposing second end that extends into the dielectric gap; 
 a first positive antenna feed terminal coupled to the first conductive segment, wherein the first positive antenna feed terminal is configured to convey first radio-frequency signals in a first frequency band, the metal strip being configured to form an open circuit impedance between the second end of the metal strip and the first conductive segment in the first frequency band; and 
 a second positive antenna feed terminal coupled to the second conductive segment, the second positive antenna feed terminal being configured to convey second radio-frequency signals in a second frequency band that is higher than the first frequency band, wherein antenna currents corresponding to the second radio-frequency signals flow along a conductive loop path that includes the second conductive segment, the metal strip, and a portion of the antenna ground. 
 
     
     
       20. The antenna defined in  claim 19 , wherein the antenna currents flow between the second segment and the second end of the metal strip across a portion of the dielectric gap.

Description:
BACKGROUND 
     This relates to electronic devices, and more particularly, to antennas for 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. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to implement wireless communications circuitry such as antenna components using compact structures. At the same time, there is a desire for wireless devices to cover a growing number of communications bands. For example, it may be desirable for a wireless device to cover many different cellular telephone communications bands at different frequencies. 
     Because antennas have the potential to interfere with each other and with components in a wireless device, care must be taken when incorporating antennas into an electronic device. Moreover, care must be taken to ensure that the antennas and wireless circuitry in a device are able to exhibit satisfactory performance over the desired range of operating frequencies. In addition, it is often difficult to perform wireless communications with a satisfactory data rate (data throughput), especially as software applications performed by wireless devices become increasingly data hungry. 
     It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless electronic devices. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry and a housing having peripheral conductive housing structures. The wireless circuitry may include an antenna that includes an antenna ground and that is fed using first and second antenna feeds. A dielectric gap may divide the peripheral conductive housing structures into first and second segments. The first segment may be separated from the antenna ground by a first slot element. The second segment may be separated from the antenna ground by a second slot element. The first antenna feed may be coupled across the first slot element and the second antenna feed may be coupled across the second slot element. 
     The first antenna feed, first slot element, and first segment may convey first radio-frequency signals in a cellular low band, a cellular low-midband, and a cellular midband. The second antenna feed and the second slot element may concurrently convey second radio-frequency signals in a cellular high band and a cellular ultra-high band. An antenna isolation element may be coupled to the antenna ground and may separate the first slot element from the second slot element. The antenna isolation element may include a metal strip having an end coupled to the antenna ground and an opposing tip that extends into the dielectric gap (e.g., the tip may be interposed between the first and second segments of the peripheral conductive housing structures). 
     The antenna isolation element may electromagnetically isolate the first radio-frequency signals in the cellular midband from the second radio-frequency signals in the cellular high band. Antenna currents in the cellular high band may flow along a conductive loop path that extends around the second slot element and that includes a portion of the antenna ground, the second segment, and the metal strip. The antenna currents may flow between the second segment and the tip of the metal strip across a portion of the dielectric gap. The antenna currents may flow from the second segment to the antenna ground through the metal strip. The metal strip may form an open circuit impedance across the dielectric gap (e.g., between the tip and the first segment) in the cellular midband. The dimensions and placement of the metal strip within the dielectric gap may be selected to interpose a desired tuning capacitance on the conductive loop path (e.g., to tune the frequency response of the second slot element). When configured in this way, the antenna may concurrently convey radio-frequency signals in both the cellular midband and the cellular high band with satisfactory antenna efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with some embodiments. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with some embodiments. 
         FIG. 3  is a schematic diagram of illustrative wireless communications circuitry in accordance with some embodiments. 
         FIG. 4  is a diagram of illustrative wireless circuitry including multiple antennas for performing multiple-input and multiple-output (MIMO) communications in accordance with some embodiments. 
         FIG. 5  is a schematic diagram of an illustrative inverted-F antenna in accordance with some embodiments. 
         FIG. 6  is a schematic diagram of an illustrative slot antenna in accordance with some embodiments. 
         FIG. 7  is a top view of illustrative antennas formed from housing structures in an electronic device in accordance with some embodiments. 
         FIG. 8  is a top view of an illustrative antenna having multiple positive antenna feed terminals and an isolation element coupled between slot elements for optimizing radio-frequency performance across multiple different communications bands in accordance with some embodiments. 
         FIG. 9  is a flow chart of illustrative steps that may be involved in adjusting an antenna of the type shown in  FIG. 8  in accordance with some embodiments. 
         FIG. 10  is a plot of antenna performance (standing wave ratio) of an illustrative antenna of the type shown in  FIG. 8  in accordance with some embodiments. 
     
    
    
     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 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 the 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, a wireless access point, wireless base station, an electronic device incorporated into a kiosk, building, or vehicle, 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 rear housing wall (e.g., 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 (rear 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. If desired, buttons may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port  24 . 
     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, peripheral conductive housing sidewall structures, peripheral conductive housing sidewalls, peripheral conductive sidewalls, or a peripheral conductive housing member (as examples). Peripheral conductive housing structures  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, three, four, five, six, or more than six separate structures may be used in forming peripheral conductive housing structures  16 . 
     It is not necessary for peripheral conductive housing structures  16  to have a uniform cross-section. For example, the top portion of peripheral conductive housing structures  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral conductive housing structures  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral conductive 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 conductive housing structures  16  serve as a bezel for display  14 ), peripheral conductive housing structures  16  may run around the lip of housing  12  (i.e., peripheral conductive 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 conductive rear housing wall of device  10  may be formed from a planar metal structure and portions of peripheral conductive 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 conductive 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  and/or the conductive rear wall of housing  12  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 the rear wall 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., in regions  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 conductive housing structures  16  may be provided with peripheral gap structures. For example, peripheral conductive housing structures  16  may be provided with one or more gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral conductive 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 conductive housing structures  16  into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral conductive 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 ), six peripheral conductive segments (e.g., in an arrangement with six 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 conductive 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, near-field 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  28 . Control circuitry  28  may include storage such as storage circuitry  26 . Storage circuitry  26  may include 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. 
     Control circuitry  28  may include processing circuitry such as processing circuitry  30 . Processing circuitry  30  may be used to control the operation of device  10 . Processing circuitry  30  may include on one or more microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), etc. Control circuitry  28  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  26  (e.g., storage circuitry  26  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  26  may be executed by processing circuitry  30 . 
     Control circuitry  28  may be used to run software on device  10  such as satellite navigation applications, 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, control circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other WPAN protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), or any other desired communications protocols. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  32 . Input-output circuitry  32  may include input-output devices  38 . Input-output devices  38  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  38  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  38  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, etc. 
     Input-output circuitry  32  may include wireless communications circuitry such as wireless communications circuitry  34  (sometimes referred to herein as wireless circuitry  34 ) for wirelessly conveying radio-frequency signals. While control circuitry  28  is shown separately from wireless communications circuitry  34  in the example of  FIG. 2  for the sake of clarity, wireless communications circuitry  34  may include processing circuitry that forms a part of processing circuitry  30  and/or storage circuitry that forms a part of storage circuitry  26  of control circuitry  28  (e.g., portions of control circuitry  28  may be implemented on wireless communications circuitry  34 ). As an example, control circuitry  28  (e.g., processing circuitry  30 ) may include baseband processor circuitry or other control components that form a part of wireless communications circuitry  34 . 
     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  36  for handling transmission and/or reception of radio-frequency signals in various radio-frequency communications bands. For example, radio-frequency transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for Wi-Fi® (IEEE 802.11) communications or communications in other wireless local area network (WLAN) bands. Radio-frequency transceiver circuitry  36  may handle the 2.4 GHz Bluetooth® communications band or other wireless personal area network (WPAN) bands. Radio-frequency transceiver circuitry  36  may include cellular telephone transceiver circuitry for handling wireless communications in frequency ranges such as a cellular low band (LB) from 600 to 960 MHz, a cellular low-midband (LMB) from 1410 to 1510 MHz, a cellular midband (MB) from 1710 to 2170 MHz, a cellular high band (HB) from 2300 to 2700 MHz, a cellular ultra-high band (UHB) from 3300 to 5000 MHz, or other communications bands between 600 MHz and 5000 MHz or other suitable frequencies (as examples). 
     In one suitable arrangement, radio-frequency transceiver circuitry  36  may handle 4G frequency bands between 3300 and 5000 MHz such as Long Term Evolution (LTE) bands B42 (e.g., 3400 MHz-3600 MHz) and B48 (e.g., 3500-3700) as well as 5G frequency bands (e.g., 5G NR bands) below 6 GHz such as 5G bands N77 (e.g., 3300-4200 MHz), N78 (e.g., 3300-3800 MHz), and N79 (e.g., 4400-5000 MHz). If desired, radio-frequency transceiver circuitry  36  may include a first transceiver integrated circuit (chip) for handling 4G communications and a second transceiver integrated circuit (chip) for handling 5G communications (e.g., the first transceiver integrated circuit may operate under a 4G radio access technology whereas the second transceiver integrated circuit may operate under a 5G radio access technology). Each transceiver integrated circuit may be coupled to one or of the same antennas over one or more radio-frequency transmission lines. For example, each transceiver integrated circuit may be coupled to the same antenna feeds or different antenna feeds of the same antenna via the same radio-frequency transmission line or via separate radio-frequency transmission lines. Filter circuitry (e.g., duplexer circuitry, diplexer circuitry, low pass filter circuitry, high pass filter circuitry, band pass filter circuitry, band stop filter circuitry, etc.), switching circuitry, multiplexing circuitry, or any other desired circuitry may be used to isolate radio-frequency signals conveyed by the first and second transceiver integrated circuits over the same antennas or antenna feeds (e.g., filtering circuitry or multiplexing circuitry may be interposed on a radio-frequency transmission line shared by the first and second transceiver integrated circuits). 
     Radio-frequency transceiver circuitry  36  may handle voice data and non-voice data. Radio-frequency transceiver circuitry  36  may include circuitry for other short-range and long-range wireless links if desired. For example, radio-frequency transceiver circuitry  36  may include 60 GHz transceiver circuitry (e.g., millimeter wave transceiver circuitry), circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Radio-frequency transceiver circuitry  36  may include global positioning system (GPS) receiver circuitry for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. In Wi-Fi® 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 , radio-frequency transceiver circuitry  36  in wireless communications circuitry  34  may be coupled to antenna structures such as a given antenna  40  using paths such as path  50 . Wireless communications circuitry  34  may be coupled to control circuitry  28 . Control circuitry  28  may be coupled to input-output devices  38 . Input-output devices  38  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  40  with the ability to cover communications frequencies of interest, antenna  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  40  may be provided with adjustable circuits such as tunable components  42  to tune the antenna over communications (frequency) bands of interest. Tunable components  42  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  42  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  56  that adjust inductance values, capacitance values, or other parameters associated with tunable components  42 , thereby tuning antenna  40  to cover desired communications bands. Antenna tuning components that are used to adjust the frequency response of antenna  40  such as tunable components  42  may sometimes be referred to herein as antenna tuning components, tuning components, antenna tuning elements, tuning elements, adjustable tuning components, adjustable tuning elements, or adjustable components. 
     Path  50  may include one or more transmission lines. As an example, path  50  of  FIG. 3  may be a transmission line having a positive signal conductor such as signal conductor  52  and a ground signal conductor such as ground conductor  54 . Path  50  may sometimes be referred to herein as transmission line  50  or radio-frequency transmission line  50 . 
     Transmission line  50  may, for example, include a coaxial cable transmission line (e.g., ground conductor  54  may be implemented as a grounded conductive braid surrounding signal conductor  52  along its length), a stripline transmission line, a microstrip transmission line, coaxial probes realized by a metalized via, an edge-coupled microstrip transmission line, an edge-coupled stripline transmission line, a waveguide structure (e.g., a coplanar waveguide or grounded coplanar waveguide), combinations of these types of transmission lines and/or other transmission line structures, etc. 
     Transmission lines in device  10  such as transmission line  50  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, transmission lines such as transmission line  50  may also include transmission line conductors (e.g., signal conductors  52  and ground conductors  54 ) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive). The multilayer laminated structures may, if desired, be folded or bent in multiple dimensions (e.g., two or three dimensions) and may maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). 
     A matching network (e.g., an adjustable matching network formed using tunable components  42 ) may include components such as inductors, resistors, and capacitors used in matching the impedance of antenna  40  to the impedance of transmission line  50 . 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  40  and may be tunable and/or fixed components. 
     Transmission line  50  may be coupled to antenna feed structures associated with antenna  40 . As an example, antenna  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed  44  with a positive antenna feed terminal such as positive antenna feed terminal  46  and a ground antenna feed terminal such as ground antenna feed terminal  48 . Signal conductor  52  may be coupled to positive antenna feed terminal  46  and ground conductor  54  may be coupled to ground antenna feed terminal  48 . Other types of antenna feed arrangements may be used if desired. For example, antenna  40  may be fed using multiple feeds each coupled to a respective port of radio-frequency transceiver circuitry  36  over a corresponding transmission line. If desired, signal conductor  52  may be coupled to multiple locations on antenna  40  (e.g., antenna  40  may include multiple positive antenna feed terminals coupled to signal conductor  52  of the same transmission line  50 ). Switches may be interposed on the signal conductor between radio-frequency transceiver circuitry  36  and the positive antenna feed terminals if desired (e.g., to selectively activate one or more positive antenna feed terminals at any given time). The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Control circuitry  28  may use information from a proximity sensor, 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 port  24  ( FIG. 1 ), information from one or more antenna impedance sensors, information on desired frequency bands to use for communications, and/or other information in determining when antenna  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 components such as tunable components  42  to ensure that antenna  40  operates as desired. Adjustments to tunable components  42  may also be made to extend the frequency coverage of antenna  40  (e.g., to cover desired communications bands that extend over a range of frequencies larger than antenna  40  would cover without tuning). 
     Antenna  40  may include antenna resonating element structures (sometimes referred to herein as radiating element structures), antenna ground plane structures (sometimes referred to herein as ground plane structures, ground structures, or antenna ground structures), an antenna feed such as feed  44 , and other components (e.g., tunable components  42 ). Antenna  40  may be configured to form any suitable type of antenna. With one suitable arrangement, which is sometimes described herein as an example, antenna  40  is used to implement a hybrid inverted-F-slot antenna that includes both inverted-F and slot antenna resonating elements. 
     If desired, multiple antennas  40  may be formed in device  10 . Each antenna  40  may be coupled to transceiver circuitry such as radio-frequency transceiver circuitry  36  over respective transmission lines such as transmission line  50 . If desired, two or more antennas  40  may share the same transmission line  50 .  FIG. 4  is a diagram showing how device  10  may include multiple antennas  40  for performing wireless communications. 
     As shown in  FIG. 4 , device  10  may include two or more antennas  40  such as a first antenna  40 - 1 , a second antenna  40 - 2 , a third antenna  40 - 3 , and a fourth antenna  40 - 4 . Antennas  40  may be provided at different locations within housing  12  of device  10 . For example, antennas  40 - 1  and  40 - 2  may be formed within region  22  at a first (upper) end of housing  12  whereas antennas  40 - 3  and  40 - 4  are formed within region  20  at an opposing second (lower) end of housing  12 . In the example of  FIG. 4 , housing  12  has a rectangular periphery (e.g., a periphery having four corners) and each antenna  40  is formed at a respective corner of housing  12 . This example is merely illustrative and, in general, antennas  40  may be formed at any desired locations within housing  12 . 
     Wireless communications circuitry  34  may include input-output ports such as port  60  for interfacing with digital data circuits in control circuitry (e.g., control circuitry  28  of  FIG. 3 ). Wireless communications circuitry  34  may include baseband circuitry such as baseband (BB) processor  62  and radio-frequency transceiver circuitry such as radio-frequency transceiver circuitry  36 . 
     Port  60  may receive digital data from control circuitry that is to be transmitted by radio-frequency transceiver circuitry  36 . Incoming data that has been received by radio-frequency transceiver circuitry  36  and baseband processor  62  may be supplied to control circuitry via port  60 . 
     Radio-frequency transceiver circuitry  36  may include one or more transmitters and one or more receivers. For example, radio-frequency transceiver circuitry  36  may include multiple remote wireless transceivers  61  such as a first transceiver  61 - 1 , a second transceiver  61 - 2 , a third transceiver  61 - 3 , and a fourth transceiver  61 - 4  (e.g., transceiver circuits for handling voice and non-voice cellular telephone communications in cellular telephone communications bands). Each transceiver  61  may be coupled to a respective antenna  40  over a corresponding transmission line  50  (e.g., a first transmission line  50 - 1 , a second transmission line  50 - 2 , a third transmission line  50 - 3 , and a fourth transmission line  50 - 4 ). For example, first transceiver  61 - 1  may be coupled to antenna  40 - 1  over transmission line  50 - 1 , second transceiver  61 - 2  may be coupled to antenna  40 - 2  over transmission line  50 - 2 , third transceiver  61 - 3  may be coupled to antenna  40 - 3  over transmission line  50 - 3 , and fourth transceiver  61 - 4  may be coupled to antenna  40 - 4  over transmission line  50 - 4 . 
     Radio-frequency front end circuits  58  may be interposed on each transmission line  50  (e.g., a first front end circuit  58 - 1  may be interposed on transmission line  50 - 1 , a second front end circuit  58 - 2  may be interposed on transmission line  50 - 2 , a third front end circuit  58 - 3  may be interposed on transmission line  50 - 3 , etc.). Front end circuits  58  may each include switching circuitry, filter circuitry (e.g., duplexer and/or diplexer circuitry, notch filter circuitry, low pass filter circuitry, high pass filter circuitry, bandpass filter circuitry, etc.), impedance matching circuitry for matching the impedance of transmission lines  50  to the corresponding antenna  40 , networks of active and/or passive components such as tunable components  42  of  FIG. 3 , radio-frequency coupler circuitry for gathering antenna impedance measurements, amplifier circuitry (e.g., low noise amplifiers and/or power amplifiers) or any other desired radio-frequency circuitry. If desired, front end circuits  58  may include switching circuitry that is configured to selectively couple antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  to different respective transceivers  61 - 1 ,  61 - 2 ,  61 - 3 , and  61 - 4  (e.g., so that each antenna can handle communications for different transceivers  61  over time based on the state of the switching circuits in front end circuits  58 ). 
     If desired, front end circuits  58  may include filtering circuitry (e.g., duplexers and/or diplexers) that allow the corresponding antenna  40  to transmit and receive radio-frequency signals at the same time (e.g., using a frequency domain duplexing (FDD) scheme). Antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may transmit and/or receive radio-frequency signals in respective time slots or two or more of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may transmit and/or receive radio-frequency signals concurrently. In general, any desired combination of transceivers  61 - 1 ,  61 - 2 ,  61 - 3 , and  61 - 4  may transmit and/or receive radio-frequency signals using the corresponding antenna  40  at a given time. In one suitable arrangement, each of transceivers  61 - 1 ,  61 - 2 ,  61 - 3 , and  61 - 4  may receive radio-frequency signals while a given one of transceivers  61 - 1 ,  61 - 2 ,  61 - 3 , and  61 - 4  transmits radio-frequency signals at a given time. 
     Amplifier circuitry such as one or more power amplifiers may be interposed on transmission lines  50  and/or formed within radio-frequency transceiver circuitry  36  for amplifying radio-frequency signals output by transceivers  61  prior to transmission over antennas  40 . Amplifier circuitry such as one or more low noise amplifiers may be interposed on transmission lines  50  and/or formed within radio-frequency transceiver circuitry  36  for amplifying radio-frequency signals received by antennas  40  prior to conveying the received signals to transceivers  61 . 
     In the example of  FIG. 4 , separate front end circuits  58  are formed on each transmission line  50 . This is merely illustrative. If desired, two or more transmission lines  50  may share the same front end circuits  58  (e.g., front end circuits  58  may be formed on the same substrate, module, or integrated circuit). 
     Each of transceivers  61  may, for example, include circuitry for converting baseband signals received from baseband processor  62  over paths  63  into corresponding radio-frequency signals. For example, transceivers  61  may each include mixer circuitry for up-converting the baseband signals to radio-frequencies prior to transmission over antennas  40 . Transceivers  61  may include digital to analog converter (DAC) and/or analog to digital converter (ADC) circuitry for converting signals between digital and analog domains. Each of transceivers  61  may include circuitry for converting radio-frequency signals received from antennas  40  over transmission lines  50  into corresponding baseband signals. For example, transceivers  61  may each include mixer circuitry for down-converting the radio-frequency signals to baseband frequencies prior to conveying the baseband signals to baseband processor  62  over paths  63 . 
     Each transceiver  61  may be formed on the same substrate, integrated circuit, or module (e.g., radio-frequency transceiver circuitry  36  may be a transceiver module having a substrate or integrated circuit on which each of transceivers  61  is formed) or two or more transceivers  61  may be formed on separate substrates, integrated circuits, or modules. Baseband processor  62  and front end circuits  58  may be formed on the same substrate, integrated circuit, or module as transceivers  61  or may be formed on separate substrates, integrated circuits, or modules from transceivers  61 . In another suitable arrangement, radio-frequency transceiver circuitry  36  may include a single transceiver  61  having four ports, each of which is coupled to a respective transmission line  50 , if desired. Each transceiver  61  may include transmitter and receiver circuitry for both transmitting and receiving radio-frequency signals. In another suitable arrangement, one or more transceivers  61  may perform only signal transmission or signal reception (e.g., one or more of transceivers  61  may be a dedicated transmitter or dedicated receiver). 
     In the example of  FIG. 4 , antennas  40 - 1  and  40 - 4  may occupy a larger space (e.g., a larger area or volume within device  10 ) than antennas  40 - 2  and  40 - 3 . This may allow antennas  40 - 1  and  40 - 4  to support communications at longer wavelengths (i.e., lower frequencies) than antennas  40 - 2  and  40 - 3 . This is merely illustrative and, if desired, each of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may occupy the same volume or may occupy different volumes. Antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may be configured to convey radio-frequency signals in at least one common frequency band. If desired, one or more of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may handle radio-frequency signals in at least one frequency band that is not covered by one or more of the other antennas in device  10 . 
     If desired, each antenna  40  and each transceiver  61  may handle radio-frequency communications in multiple frequency bands (e.g., multiple cellular telephone communications bands). For example, transceiver  61 - 1 , antenna  40 - 1 , transceiver  61 - 4 , and antenna  40 - 4 , may handle radio-frequency signals in a first frequency band such as a cellular low band between 600 and 960 MHz, a second frequency band such as a cellular low-midband between 1410 and 1510 MHz, a third frequency band such as a cellular midband between 1700 and 2200 MHz, a fourth frequency band such as a cellular high band between 2300 and 2700 MHz, and/or a fifth frequency band such as a cellular ultra-high band between 3300 and 5000 MHz. Transceiver  61 - 2 , antenna  40 - 2 , transceiver  61 - 3 , and antenna  40 - 3  may handle radio-frequency signals in some or all of these bands (e.g., in scenarios where the volume of antennas  40 - 3  and  40 - 2  is large enough to support frequencies in the low band). 
     The example of  FIG. 4  is merely illustrative. In general, antennas  40  may cover any desired frequency bands. Housing  12  may have any desired shape. Antennas  40  may be formed at any desired locations within housing  12 . Forming each of antennas  40 - 1  through  40 - 4  at different corners of housing  12  may, for example, maximize the multi-path propagation of wireless data conveyed by antennas  40  to optimize overall data throughput for wireless communications circuitry  34 . 
     When operating using a single antenna  40 , a single stream of wireless data may be conveyed between device  10  and external communications equipment (e.g., one or more other wireless devices such as wireless base stations, access points, cellular telephones, computers, etc.). This may impose an upper limit on the data rate (data throughput) obtainable by wireless communications circuitry  34  in communicating with the external communications equipment. As software applications and other device operations increase in complexity over time, the amount of data that needs to be conveyed between device  10  and the external communications equipment typically increases, such that a single antenna  40  may not be capable of providing sufficient data throughput for handling the desired device operations. 
     In order to increase the overall data throughput of wireless communications circuitry  34 , multiple antennas  40  may be operated using a multiple-input and multiple-output (MIMO) scheme. When operating using a MIMO scheme, two or more antennas  40  on device  10  may be used to convey multiple independent streams of wireless data at the same frequency. This may significantly increase the overall data throughput between device  10  and the external communications equipment relative to scenarios where only a single antenna  40  is used. In general, the greater the number of antennas  40  that are used for conveying wireless data under the MIMO scheme, the greater the overall throughput of wireless communications circuitry  34 . 
     In order to perform wireless communications under a MIMO scheme, antennas  40  need to convey data at the same frequencies. If desired, wireless communications circuitry  34  may perform so-called two-stream (2×) MIMO operations (sometimes referred to herein as 2×MIMO communications or communications using a 2×MIMO scheme) in which two antennas  40  are used to convey two independent streams of radio-frequency signals at the same frequency. Wireless communications circuitry  34  may perform so-called four-stream (4×) MIMO operations (sometimes referred to herein as 4×MIMO communications or communications using a 4×MIMO scheme) in which four antennas  40  are used to convey four independent streams of radio-frequency signals at the same frequency. Performing 4×MIMO operations may support higher overall data throughput than 2×MIMO operations because 4×MIMO operations involve four independent wireless data streams whereas 2×MIMO operations involve only two independent wireless data streams. If desired, antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may perform 2×MIMO operations in some frequency bands and may perform 4×MIMO operations in other frequency bands (e.g., depending on which bands are handled by which antennas). Antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may perform 2×MIMO operations in some bands concurrently with performing 4×MIMO operations in other bands, for example. 
     As one example, antennas  40 - 1  and  40 - 4  (and the corresponding transceivers  61 - 1  and  61 - 4 ) may perform 2×MIMO operations by conveying radio-frequency signals at the same frequency in a cellular low band between 600 MHz and 960 MHz. At the same time, antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may collectively perform 4×MIMO operations by conveying radio-frequency signals at the same frequency in a cellular midband between 1700 and 2200 MHz, at the same frequency in a cellular high band (HB) between 2300 and 2700 MHz, and/or at the same frequency in a cellular ultra-high band (UHB) between 3300 and 5000 MHz (e.g., antennas  40 - 1  and  40 - 4  may perform 2×MIMO operations in the low band concurrently with performing 4×MIMO operations in the midband, high band, and/or ultra-high band). This example is merely illustrative and, in general, any desired number of antennas may be used to perform any desired MIMO operations in any desired frequency bands. 
     If desired, antennas  40 - 1  and  40 - 2  may include switching circuitry that is adjusted by control circuitry (e.g., control circuitry  28  of  FIG. 3 ). Control circuitry  28  may control the switching circuitry in antennas  40 - 1  and  40 - 2  to configure antenna structures in antennas  40 - 1  and  40 - 2  to form a single antenna  40 U in region  22  of device  10 . Similarly, antennas  40 - 3  and  40 - 4  may include switching circuitry that is adjusted by control circuitry  28 . Control circuitry  28  may control the switching circuitry in antennas  40 - 3  and  40 - 4  to form a single antenna  40 L (e.g., an antenna  40 L that includes antenna structures from antennas  40 - 3  and  40 - 4 ) in region  20  of device  10 . Antenna  40 U may, for example, be formed at an upper end of housing  12  and may therefore sometimes be referred to herein as upper antenna  40 U. Antenna  40 L may be formed at an opposing lower end of housing  12  and may therefore sometimes be referred to herein as lower antenna  40 L. When antennas  40 - 1  and  40 - 2  are configured to form upper antenna  40 U and antennas  40 - 3  and  40 - 4  are configured to form lower antenna  40 L, wireless communications circuitry  34  may perform 2×MIMO operations using antennas  40 U and  40 L in any desired frequency bands. If desired, control circuitry  28  may toggle the switching circuitry over time to switch wireless communications circuitry  34  between a first mode in which antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  perform 2×MIMO operations in any desired frequency bands and 4×MIMO operations in any desired frequency bands and a second mode in which antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  are configured to form antennas  40 U and  40 L that perform 2×MIMO operations in any desired frequency bands. 
     If desired, wireless communications circuitry  34  may convey wireless data with multiple antennas on one or more external devices (e.g., multiple wireless base stations) in a scheme sometimes referred to as carrier aggregation. When operating using a carrier aggregation scheme, the same antenna  40  may convey radio-frequency signals with multiple antennas (e.g., antennas on different wireless base stations) at different respective frequencies (sometimes referred to herein as carrier frequencies, channels, carrier channels, or carriers). For example, antenna  40 - 1  may receive radio-frequency signals from a first wireless base station at a first frequency, from a second wireless base station at a second frequency, and a from a third base station at a third frequency. The received signals at different frequencies may be simultaneously processed (e.g., by transceiver  61 - 1 ) to increase the communications bandwidth of transceiver  61 - 1 , thereby increasing the data rate of transceiver  61 - 1 . Similarly, antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may perform carrier aggregation at two, three, or more than three frequencies within any desired frequency bands. This may serve to further increase the overall data throughput of wireless communications circuitry  34  relative to scenarios where no carrier aggregation is performed. For example, the data throughput of wireless communications circuitry  34  may increase for each carrier frequency that is used (e.g., for each wireless base station that communicates with each of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4 ). 
     By performing communications using both a MIMO scheme and a carrier aggregation scheme, the data throughput of wireless communications circuitry  34  may be even greater than in scenarios where either a MIMO scheme or a carrier aggregation scheme is used. The data throughput of wireless communications circuitry  34  may, for example, increase for each carrier frequency that is used by antennas  40  (e.g., each carrier frequency may contribute 40 megabits per second (Mb/s) or some other throughput to the total throughput of wireless communications circuitry  34 ). The example of  FIG. 4  is merely illustrative. If desired, antennas  40  may cover any desired number of frequency bands at any desired frequencies. More than four antennas  40  or fewer than four antennas  40  may perform MIMO and/or carrier aggregation operations at non-near-field communications frequencies if desired. 
     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. 5 . 
     When using an inverted-F antenna structure as shown in  FIG. 5 , antenna  40  may include an antenna resonating element  64  (sometimes referred to herein as antenna radiating element  64 ) and antenna ground  74  (sometimes referred to herein as ground plane  74  or ground  74 ). Antenna resonating element  64  may have a main resonating element arm such as resonating element arm  66 . The length of resonating element arm  66  may be selected so that antenna  40  resonates at desired operating frequencies. For example, the length of resonating element arm  66  (or a branch of resonating element arm  66 ) may be approximately one-quarter of the wavelength corresponding to a desired operating frequency for antenna  40 . Antenna  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. 5  (e.g., to enhance antenna response in one or more communications bands). 
     Resonating element arm  66  may be coupled to antenna ground  74  by return path  68 . Antenna feed  44  may include positive antenna feed terminal  46  and ground antenna feed terminal  48  and may run parallel to return path  68  between resonating element arm  66  and antenna ground  74 . If desired, antenna  40  may have more than one resonating element 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.). For example, resonating element arm  66  may have left and right branches that extend outwardly from antenna feed  44  and return path  68 . If desired, multiple feeds may be used to feed antennas such as antenna  40 . Resonating element arm  66  may follow any desired path having any desired shape (e.g., curved and/or straight paths, meandering paths, etc.). 
     If desired, antenna  40  may include one or more adjustable circuits (e.g., tunable components  42  of  FIG. 3 ) that are coupled to resonating element arm  66 . As shown in  FIG. 5 , for example, tunable components such as adjustable inductor  70  may be coupled between antenna resonating element structures in antenna  40  such as resonating element arm  66  and antenna ground  74  (e.g., adjustable inductor  70  may bridge the gap between resonating element arm  66  and antenna ground  74 ). Adjustable inductor  70  may exhibit an inductance value that is adjusted in response to control signals  72  provided to adjustable inductor  70  from control circuitry  28  ( FIG. 3 ). 
     Antenna  40  may be a hybrid antenna that includes one or more slot elements. As shown in  FIG. 6 , for example, antenna  40  may be based on a slot antenna configuration having an opening such as slot  76  that is formed within conductive structures such as antenna ground  74 . Slot  76  may be filled with air, plastic, and/or other dielectrics. The shape of slot  76  may be straight or may have one or more bends (e.g., slot  76  may have an elongated shape following a meandering path). Antenna feed terminals  48  and  46  may, for example, be located on opposing sides of slot  76  (e.g., on opposing long sides). Slot  76  may sometimes be referred to herein as slot element  76 , slot antenna resonating element  76 , slot antenna radiating element  76 , or slot radiating element  76 . Slot-based radiating elements such as slot  76  of  FIG. 6  may give rise to an antenna resonance at frequencies in which the wavelength of the antenna signals is approximately equal to the perimeter of the slot. In narrow slots, the resonant frequency of slot  76  is associated with signal frequencies at which the slot length is approximately equal to a half of a wavelength of operation. 
     The frequency response of antenna  40  can be tuned using one or more tuning components (e.g., tunable components  42  of  FIG. 3 ). These components may have terminals that are coupled to opposing sides of slot  76  (e.g., the tunable components may bridge slot  76 ). If desired, tunable components may have terminals that are coupled to respective locations along the length of one of the sides of slot  76 . Combinations of these arrangements may also be used. If desired, antenna  40  may be a hybrid slot-inverted-F antenna that includes resonating elements of the type shown in both  FIG. 5  and  FIG. 6  (e.g., having resonances given by both a resonating element arm such as resonating element arm  66  of  FIG. 5  and a slot such as slot  76  of  FIG. 6 ). 
     The example of  FIG. 6  is merely illustrative. In general, slot  76  may have any desired shape (e.g., shapes with straight and/or curved edges), may follow a meandering path, etc. If desired, slot  76  may be an open slot having one or more ends that are free from conductive material (e.g., where slot  76  extends through one or more sides of antenna ground  74 ). Slot  76  may, for example, have a length approximately equal to one-quarter of the wavelength of operation in these scenarios. 
     A top interior view of an illustrative portion of device  10  that contains antennas  40 - 4  and  40 - 3  of  FIG. 4  is shown in  FIG. 7 . In the example of  FIG. 7 , antennas  40 - 3  and  40 - 4  are each formed using hybrid slot-inverted-F antenna structures that includes resonating elements of the types shown in  FIGS. 5 and 6 . 
     As shown in  FIG. 7 , peripheral conductive housing structures  16  may be segmented (divided) by dielectric-filled gaps  18  (e.g., plastic gaps) such as a first gap  18 - 1 , a second gap  18 - 2 , and a third gap  18 - 3 . Each of gaps  18 - 1 ,  18 - 2 , and  18 - 3  may be formed within peripheral structures  16  along respective sides of device  10 . For example, gap  18 - 1  may be formed at a first side of device  10  and may separate a first segment  16 - 1  of peripheral conductive housing structures  16  from a second segment  16 - 2  of peripheral conductive housing structures  16 . Gap  18 - 3  may be formed at a second side of device  10  and may separate second segment  16 - 2  from a third segment  16 - 3  of peripheral conductive housing structures  16 . Gap  18 - 2  may be formed at a third side of device  10  and may separate third segment  16 - 3  from a fourth segment  16 - 4  of peripheral conductive housing structures  16 . 
     The resonating element for antenna  40 - 4  may include an inverted-F antenna resonating element arm (e.g., resonating element arm  66  of  FIG. 5 ) that is formed from segment  16 - 3 . The resonating element for antenna  40 - 3  may include an inverted-F antenna resonating element arm that is formed from segment  16 - 2 . Air and/or other dielectric may fill slot  76  between arm segments  16 - 2  and  16 - 3  and ground structures  78 . 
     Ground structures  78  may include one or more planar metal layers such as a metal layer used to form a rear housing wall for device  10 , a metal layer that forms an internal support structure for device  10 , conductive traces on a printed circuit board, and/or any other desired conductive layers in device  10 . Ground structures  78  may extend from segment  16 - 1  to segment  16 - 4  of peripheral conductive housing structures  16 . Ground structures  78  may be coupled to segments  16 - 1  and  16 - 4  using conductive adhesive, solder, welds, conductive screws, conductive pins, and/or any other desired conductive interconnect structures. If desired, ground structures  78  and segments  16 - 1  and  16 - 4  may be formed from different portions of a single integral conductive structure (e.g., a conductive housing for device  10 ). 
     Ground structures  78  need not be confined to a single plane and may, if desired, include multiple layers located in different planes or non-planar structures. Ground structures  78  may include conductive (e.g., grounded) portions of other electrical components within device  10 . For example, ground structures  78  may include conductive portions of display  14  ( FIG. 1 ). Conductive portions of display  14  may include a metal frame for display  14 , a metal backplate for display  14 , shielding layers or shielding cans for display  14 , pixel circuitry in display  14 , touch sensor circuitry (e.g., touch sensor electrodes) for display  14 , and/or any other desired conductive structures in display  14  or used for mounting display  14  to the housing for device  10 . 
     Ground structures  78  and segments  16 - 1  and  16 - 4  may form portions of antenna ground  74  ( FIGS. 5 and 6 ) for antennas  40 - 3  and  40 - 4 . If desired, slot  76  may be configured to form slot antenna resonating element structures that contribute to the overall performance of antennas  40 - 3  and/or  40 - 4 . Slot  76  may extend from gap  18 - 1  to gap  18 - 2  (e.g., the ends of slot  76  which may sometimes be referred to as open ends, may be formed by gaps  18 - 1  and  18 - 2 ). Slot  76  may have an elongated shape having any suitable length (e.g., about 4-20 cm, more than 2 cm, more than 4 cm, more than 8 cm, more than 12 cm, less than 25 cm, less than 10 cm, etc.) and any suitable width (e.g., approximately 2 mm, less than 2 mm, less than 3 mm, less than 4 mm, 1-3 mm, etc.). Gap  18 - 3  may be continuous with and extend perpendicular to a portion of slot  76  along the longitudinal axis of the longest portion of slot  76  (e.g., the portion of slot  76  extending parallel to the X-axis of  FIG. 7 ). If desired, slot  76  may include vertical portions that extend parallel to longitudinal axis  81  (e.g., the Y-axis of  FIG. 7 ) and beyond gaps  18 - 1  and  18 - 2 . 
     As shown in  FIG. 7 , a portion  80  of ground structures  78  may protrude into slot  76  towards segment  16 - 3 . Portion  80  of ground structures  78  (sometimes referred to herein as protrusion  80 , ground protrusion  80 , extension  80 , or ground extension  80 ) may be located closer to segment  16 - 3  than other portions of ground structures  78  (e.g., ground extension  80  may extend parallel to longitudinal axis  81  towards segment  16 - 3 ). Ground extension  80  may, for example, support components for display  14  of  FIG. 1  (e.g., components that allow active area AA of display  14  to extend across substantially all of the front face of device  10 ). If desired, ground extension  80  may form a distributed capacitance with segment  16 - 3  that tunes the frequency response of antenna  40 - 4 . 
     Slot  76  may be filled with dielectric such as air, plastic, ceramic, or glass. For example, plastic may be inserted into portions of slot  76  and this plastic may be flush with the exterior of the housing for device  10 . Dielectric material in slot  76  may lie flush with dielectric material in gaps  18 - 1 ,  18 - 2 , and  18 - 3  at the exterior of the housing  12  if desired. The example of  FIG. 7  in which slot  76  has a U-shape is merely illustrative. If desired, slot  76  may have any other desired shapes (e.g., a rectangular shape, meandering shapes having curved and/or straight edges, etc.). 
     In general, it may be desirable to support multiple frequency bands using antenna  40 - 4  (e.g., using a MIMO scheme with the other antennas in device  10  to maximize the data rate for wireless communications circuitry  34  of  FIG. 2 ). For example, antenna  40 - 4  may support communications in a cellular low band, a cellular low-midband, a cellular high band, and/or a cellular ultra-high band. In order to support operations at multiple frequency bands with satisfactory antenna efficiency, antenna  40 - 4  may be provided with multiple positive antenna feed terminals such as positive antenna feed terminal  46  of  FIGS. 3, 5, and 6 . The positive antenna feed terminals may be located at different points along segments  16 - 3  and  16 - 4 , for example. 
       FIG. 8  is a top interior view of an illustrative portion of device  10  that contains antenna  40 - 4 . Antenna  40 - 4  of  FIG. 8  may, for example, support wireless communications with satisfactory antenna efficiency across multiple frequency bands of interest. 
     As shown in  FIG. 8 , antenna  40 - 4  may be formed at a corner of device  10  and may include an antenna resonating element arm  66  formed from segment  16 - 3  of peripheral conductive housing structures  16 . Antenna  40 - 4  may be fed using multiple antenna feeds such as a first antenna feed  44 - 1  having a first positive antenna feed terminal  46 - 1  coupled to segment  16 - 3  and a second antenna feed  44 - 2  having a second positive antenna feed terminal  46 - 2  coupled to segment  16 - 4 . The ground antenna feed terminals for first antenna feed  44 - 1  and second antenna feed  44 - 2  may be coupled to ground structures  78 , but are omitted from  FIG. 8  for the sake of clarity. 
     Ground structures  78  may have any desired shape within device  10 . For example, the lower edge of ground structures  78  (e.g., the edge of ground structures  78  defining the upper edge of slot  76 ) may be aligned with gap  18 - 2  in peripheral conductive housing structures  16  (e.g., upper edge  92  or lower edge  96  of gap  18 - 2  may be aligned with the edge of ground structures  78  defining the portion of slot  76  adjacent to gap  18 - 2 ). If desired, as shown in the example of  FIG. 8 , ground structures  78  may include a slot such as vertical slot  120  adjacent to gap  18 - 2  that extends above upper edge  92  of gap  18 - 2  (e.g., in the direction of the Y-axis of  FIG. 8 ). Vertical slot  120  may, for example, have two or more edges that are defined by ground structures  78  and one edge that is defined by segment  16 - 4  of the peripheral conductive housing structures. Vertical slot  120  may have an open end defined by an open end of slot  76  at gap  18 - 2  and an opposing closed end defined by ground structures  78 . Vertical slot  120  may therefore sometimes be referred to herein as a continuous portion of slot  76 , a vertical portion of slot  76 , or a vertical extension of slot  76 . 
     Vertical slot  120  may have a width  116  that separates ground structures  78  from segment  16 - 4  of peripheral conductive structures  16  (e.g., in the direction of the X-axis of  FIG. 7 ). Vertical slot  120  may have any desired width  116  (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.). Vertical slot  120  may have an elongated length  114  (e.g., perpendicular to width  116 ). Length  114  may be, for example, 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. 
     Portions of vertical slot  120  may contribute slot antenna resonances to antenna  40 - 4  in one or more frequency bands if desired. For example, length  114  and width  116  of vertical slot  120  (e.g., the perimeter of vertical slot  120  shown by dashed path  126 ) may be selected so that antenna  40 - 4  resonates at desired operating frequencies. If desired, the overall length of slots  76  and  120  may be selected so that antenna  40 - 4  resonates at desired operating frequencies. 
     Antenna  40 - 4  may include adjustable components  108 ,  102 , and  118  (e.g., tunable components  42  of  FIG. 3 ). Adjustable component  108  may have a first terminal  110  coupled to ground structures  78  and a second terminal  112  coupled to segment  16 - 3  (e.g., adjustable component  108  may be coupled across slot  76 ). Adjustable component  102  may have a first terminal  104  coupled to ground structures  78  and a second terminal  106  coupled to segment  16 - 3  (e.g., adjustable component  102  may be coupled across slot  76 ). Adjustable component  118  may have a first terminal  124  coupled to ground structures  78  and a second terminal  122  coupled to segment  16 - 3  (e.g., adjustable component  118  may be coupled across vertical slot  120 ). Positive antenna feed terminal  46 - 2  may be interposed on segment  16 - 4  between terminal  122  and gap  18 - 2 . Positive antenna feed terminal  46 - 1  may be interposed on segment  16 - 3  between terminals  112  and  106 . Terminal  106  may be interposed on segment  16 - 3  between positive antenna feed terminal  46 - 1  and gap  18 - 2 . Terminal  112  may be interposed on segment  16 - 3  between positive antenna feed terminal  46 - 1  and gap  18 - 3 . These examples are merely illustrative and, if desired, these terminals may be arranged in any desired order. Return paths for antenna  40 - 4  such as return path  68  of  FIG. 5  may be formed by adjustable components  108 ,  102 , and/or  118 . 
     Adjustable components  108 ,  102 , and  118  may each include switches coupled to fixed components such as inductors for providing adjustable amounts of inductance, a short circuit path, and/or an open circuit between peripheral conductive housing structures  16  and ground structures  78 . If desired, adjustable components  108 ,  102 , and  118  may also or alternatively 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  108 ,  102 , and  118  may include other components such as adjustable return path switches, switches coupled to capacitors, or any other desired components. 
     The length of resonating element arm  66  (and the perimeter of vertical slot  120 ) may be selected so that antenna  40 - 4  radiates at desired operating frequencies such as frequencies in a cellular low band (e.g., a frequency band between about 600 MHz and 960 MHz), a cellular low-midband (e.g., a frequency band between about 1410 MHz and 1510 MHz), a cellular midband (e.g., a frequency band between about 1710 MHz and 2170 MHz), and/or a cellular ultra-high band (e.g., a frequency band between about 3300 MHz and 5000 MHz). 
     Positive antenna feed terminal  46 - 1  may be used to convey radio-frequency signals in the cellular low band as well as signals at frequencies higher than the cellular low band. For example, the length of resonating element arm  66  extending from positive antenna feed terminal  46 - 1  to gap  18 - 2 , as shown by dashed path  132 , may be selected to cover frequencies in the cellular low-midband and/or the cellular midband. This length may be approximately equal to one-quarter of the wavelength corresponding to a frequency in one of these frequency bands (e.g., where the wavelength is an effective wavelength that accounts for dielectric loading by the dielectric materials in slot  76 ). If desired, adjustable component  102  may be adjusted to tune the frequency response associated with dashed path  132  between the cellular low-midband and the cellular midband (e.g., adjustable component  102  may have a first state at which antenna  40 - 4  covers the cellular midband and a second state at which antenna  40 - 4  covers the cellular low-midband). At the same time, the length of resonating element arm  66  extending from positive antenna feed terminal  46 - 1  to gap  18 - 3 , as shown by dashed path  130 , may be selected to cover frequencies in the cellular low band. This length may be approximately equal to one-quarter of the wavelength corresponding to a frequency in the cellular low band (e.g., where the wavelength is an effective wavelength that accounts for dielectric loading by the dielectric materials in slot  76 ). If desired, adjustable component  108  may be adjusted to tune the frequency response associated with dashed path  130  within the cellular low band. 
     Segment  16 - 4  of peripheral conductive housing structures  16  and the portion of ground structures  78  surrounding vertical slot  120  may contribute to the frequency response of antenna  40 - 4  in the cellular high band and/or the cellular ultra-high band. For example, the perimeter of vertical slot  120 , as shown by dashed path  126 , may be selected so that vertical slot  120  radiates in the cellular high band and/or the cellular ultra-high band. Positive antenna feed terminal  46 - 2  may be used to convey radio-frequency signals in the cellular high band and/or the cellular ultra-high band using vertical slot  120 . If desired, adjustable component  118  may be adjusted to tune the frequency response associated with vertical slot  120  (e.g., within the cellular high band and the cellular ultra-high band or between the cellular high band and the cellular ultra-high band). 
     Antenna  40 - 4  may concurrently convey radio-frequency signals in some or all of the cellular low band, the cellular low-midband, the cellular midband, the cellular high band, and the cellular ultra-high band using positive antenna feed terminals  46 - 1  and  46 - 2 . For example, positive antenna feed terminal  46 - 1 , segment  16 - 3 , and slot  76  may convey radio-frequency signals in the cellular low band, the cellular low-midband, and/or the cellular midband while positive antenna feed terminal  46 - 2 , and vertical slot  120  concurrently convey radio-frequency signals in the cellular high band and/or the cellular ultra-high band. However, if care is not taken, radio-frequency signals conveyed by vertical slot  120  in the cellular high band may electromagnetically interfere with radio-frequency signals conveyed by segment  16 - 3  and slot  76  in the cellular midband, thereby limiting the radio-frequency performance of antenna  40 - 4 . 
     In order to optimize isolation between vertical slot  120  and segment  16 - 3  (e.g., to allow for concurrent communications in the cellular midband and the cellular high band with satisfactory antenna efficiency), antenna  40 - 4  may include an antenna isolation element such as isolation element  84 . Isolation element  84  may separate slot  76  from vertical slot  120  and may include a conductive strip such as metal strip  88 . Metal strip  88  may have a grounded end coupled to ground structures  78  at terminal  86  and an opposing (floating) tip  90 . Tip  90  may be located within gap  18 - 2  (e.g., tip  90  may be interposed between upper edge  92  and lower edge  96  of gap  18 - 2 ). 
     Isolation element  84  (e.g., the dimensions of metal strip  88 ) may be configured to optimize radio-frequency performance within the cellular high band and/or the cellular ultra-high band for vertical slot  120  while also maximizing isolation between radiation by vertical slot  120  in the cellular high band and radiation by segment  16 - 3  and slot  76  in the cellular midband. For example, tip  90  of metal strip  88  may extend into gap  18 - 2  by distance  134  (e.g., tip  90  may extend beyond interior surface  94  of segment  16 - 3  by distance  134 ). Metal strip  88  may be separated from upper edge  92  of gap  18 - 2  by distance  100  and may be separated from lower edge  98  of gap  18 - 2  by distance  98 . Distances  134 ,  100 , and/or  98  may be selected to maximize isolation between vertical slot  120  and segment  16 - 3  while also tuning the frequency response of vertical slot  120 . 
     For example, distances  100  and/or  134  may be adjusted to vary the capacitive coupling between metal strip  88  and segment  16 - 4  and to thereby tune the frequency response of vertical slot  120  (e.g., greater distances  134  and lesser distances  100  may be associated with increased capacitive coupling between metal strip  88  and segment  16 - 4 ). Positive antenna feed terminal  46 - 2  may convey antenna currents I at frequencies in the cellular high band and the cellular ultra-high band. Metal strip  88  may form a (short) circuit path to ground structures  78  for antenna currents I, allowing antenna currents I to flow from positive antenna feed terminal  46 - 2  to terminal  86  on ground structures  78  through metal strip  88 . In this way, metal strip  88  may contribute to the resonance of vertical slot  120  and antenna currents I may follow a closed-loop path around vertical slot  120 , as shown by path  128 . The length of path  128  may be selected to tune the frequency response of vertical slot  120  in the cellular high band and/or the cellular ultra-high band. 
     At the same time, distances  98  and/or  134  may be selected to maximize electromagnetic isolation between vertical slot  120  and segment  16 - 3  (slot  76 ). For example, while antenna currents I in the cellular high band and cellular ultra-high band flow across distance  100  between segment  16 - 4  and metal strip  88 , segment  16 - 3  conveys antenna currents for positive antenna feed terminal  46 - 1  at lower frequencies such as frequencies in the cellular midband. Distances  98  and/or  134  may be selected so that these lower-frequency antenna currents in the cellular midband encounter an open circuit (e.g., infinite) impedance between lower edge  96  of gap  18 - 2  and metal strip  88 . This may serve to electromagnetically isolate the radio-frequency signals conveyed by segment  16 - 3  and slot  76  in the cellular midband from the radio-frequency signals conveyed by segment  16 - 4  and vertical slot  120  in the cellular high band. This may in turn allow antenna  40 - 4  to concurrently convey radio-frequency signals in both the cellular midband and the cellular high band with satisfactory antenna efficiency. 
     Metal strip  88  may be formed from an integral portion of ground structures  78  (e.g., an integral extension of ground structures  78 ), from sheet metal, from conductive traces, metal foil or sheet metal on an underlying dielectric substrate, or from any other desired conductive structures. In one suitable arrangement that is sometimes described herein as an example, metal strip  88  may be formed from conductive traces patterned onto dielectric  82  within slot  76 . Dielectric  82  may be formed from a single piece of plastic, ceramic, or other dielectric material that fills slot  76 , vertical slot  120 , gap  18 - 2 , and gap  18 - 3 . Metal strip  88  may be formed from conductive traces on dielectric  82  at the interior of device  10 . In another suitable arrangement, some or all of metal strip  88  may be embedded within dielectric  82  (e.g., some or all of metal strip  88  may be molded within dielectric  82 , which may be formed from one or more shots of injection molded plastic, as one example). This is merely illustrative and, if desired, separate dielectric substrates may be formed in each of these components. Terminal  86  of isolation element  84  may couple metal strip  88  to ground traces and/or a conductive support plate for device  10  in ground structures  78 . If desired, metal strip  88  may also be coupled to conductive portions of the display for device  10  (e.g., display  14  of  FIG. 1 ) at terminal  86 . 
       FIG. 9  is a flow chart of illustrative steps involved in operating device  10  to ensure satisfactory performance for antenna  40 - 4  of  FIG. 8  in all desired frequency bands of interest. 
     At step  136  of  FIG. 9 , control circuitry  28  ( FIG. 3 ) may monitor the operating environment of device  10  and/or frequencies to use for performing wireless communications. The frequencies to use may be determined based on software running on control circuitry  28  (e.g., software controlling wireless communications for device  10 ) and/or based on an assignment received from external equipment like a wireless base station. 
     Control circuitry  28  may, in general, use any suitable type of sensor measurements, wireless signal measurements, operation information, or antenna measurements to determine how device  10  is being used (e.g., to determine the operating environment of device  10 ). For example, control circuitry  28  may use sensors such as temperature sensors, capacitive proximity sensors, light-based proximity sensors, resistance sensors, force sensors, touch sensors, connector sensors that sense the presence of a connector in a connector port or that detect the presence or absence of data transmission through a connector port, sensors that detect whether wired or wireless headphones are being used with device  10 , sensors that identify a type of headphone or accessory device that is being used with device  10  (e.g., sensors that identify an accessory identifier identifying an accessory that is being used with device  10 ), or other sensors to determine how device  10  is being used. Control circuitry  28  may also use information from an orientation sensor such as an accelerometer in device  10  to help determine whether device  10  is being held in a position characteristic of right hand use or left hand use (or is being operated in free space). Control circuitry  28  may also use information about a usage scenario of device  10  in determining how device  10  is being used (e.g., information identifying whether audio data is being transmitted through speaker port  24  of  FIG. 1 , information identifying whether a telephone call is being conducted, information identifying whether a microphone on device  10  is receiving voice signals, etc.). 
     If desired, an impedance sensor or other sensor may be used in monitoring the impedance of antenna  40 - 4  or part of antenna  40 - 4 . Different antenna loading scenarios may load antenna  40 - 4  differently, so impedance measurements may help determine whether device  10  is being gripped by a user&#39;s left or right hand or is being operated in free space. Another way in which control circuitry  28  may monitor antenna loading conditions involves making received signal strength measurements on radio-frequency signals being received with antenna  40 - 4 . In this example, the adjustable circuitry of antenna  40 - 4  can be toggled between different settings and an optimum setting for antenna  40 - 4  can be identified by choosing a setting that maximizes received signal strength. In general, any desired combinations of one or more of these measurements or other measurements may be processed by control circuitry  28  to identify how device  10  is being used (i.e., to identify the operating environment of device  10 ). 
     At step  134 , control circuitry  28  may adjust the configuration of antenna  40 - 4  (e.g., antenna settings for antenna  40 - 4 ) based on the current operating environment of device  10  and/or the frequencies to use for communications (e.g., based on data or information gathered while processing step  136 ). Control circuitry  28  may adjust components  108 ,  102 , and/or  118  to adjust the frequency response of antenna  40 - 4  based on the information gathered while processing step  136  of  FIG. 9 . 
     At step  140 , antenna  40 - 4  may be used to transmit and receive wireless data using the antenna settings selected at step  138 . This process may be performed continuously, as indicated by path  142 . In this way, antenna  40 - 4  may be dynamically adjusted in real time based on the operating environment and needs of device  10 . Similar steps may be used to adjust antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and/or other antennas  40  in device  10  if desired. 
       FIG. 10  is a graph in which antenna performance (standing wave ratio) has been plotted as a function of operating frequency for antenna  40 - 4  of  FIG. 8 . As shown in  FIG. 10 , curve  146  plots an exemplary frequency response of vertical slot  120  (e.g., for radio-frequency signals conveyed over positive antenna feed terminal  46 - 2  of  FIG. 8 ). As shown by curve  146 , vertical slot  120  may exhibit a first response peak  156  in cellular high band HB (e.g., frequencies from 2300 MHz to 2700 MHz) and a second response peak  158  in cellular ultra-high band UHB (e.g., frequencies from 3300 MHz to 5000 MHz). Response peaks  156  and  158  may be associated with the perimeter of vertical slot  120 , as modified by the capacitance introduced by metal strip  88  (e.g., response peaks  156  and  158  may be supported by path  128  of  FIG. 8 ). Adjustable component  118  may be adjusted to tune the frequency response of antenna  40 - 4  within cellular high band HB and cellular ultra-high band UHB or to tune the frequency response of antenna  40 - 4  between cellular high band HB and cellular ultra-high band UHB (e.g., in scenarios where antenna  40 - 4  only covers one of bands HB and UHB at any given time). 
     Curve  144  of  FIG. 10  plots an exemplary frequency response of slot  76  and segment  16 - 3  of  FIG. 8 . As shown by curve  144 , slot  76  and segment  16 - 3  (e.g., the portion of segment  16 - 3  associated with dashed path  130  of  FIG. 8 ) may exhibit a first response peak  148  in cellular low band LB (e.g., frequencies from 600 MHz to 960 MHz). Slot  76  and segment  16 - 3  (e.g., the portion of segment  16 - 3  associated with dashed path  132  of  FIG. 8 ) may exhibit a second response peak  150  in cellular midband MB (e.g., frequencies from 1710 MHz to 2170 MHz). If desired, adjustable component  102  may be adjusted to pull response peak  150  to lower frequencies, as shown by arrow  154 . This may configure antenna  40 - 4  to exhibit response peak  152  instead of response peak  150 , allowing antenna  40 - 4  to cover cellular low-midband LMB (e.g., frequencies from 1410 MHz to 1510 MHz). In the absence of isolation element  84  of  FIG. 8 , antenna  40 - 4  may be incapable of supporting both response peaks  150  and  156  at the same time with satisfactory antenna efficiency (e.g., due to electromagnetic interference between the operation of vertical slot  120  in cellular high band HB and the operation of segment  16 - 3  and slot  76  in cellular midband MB). The presence of isolation element  84  may tune the frequency response of antenna  40 - 4  within cellular high band HB and/or cellular ultra-high band UHB while also providing sufficient electromagnetic isolation between vertical slot  120  and segment  16 - 3 . This may allow antenna  40 - 4  to convey radio-frequency signals in cellular midband MB using positive antenna feed terminal  46 - 1  of  FIG. 8  concurrently with conveying radio-frequency signals in cellular high band HB using positive antenna feed terminal  46 - 2  of  FIG. 8  (e.g., while allowing for satisfactory antenna efficiency in both cellular high band HB and cellular midband MB). 
     The example of  FIG. 10  is merely illustrative. In general, antenna  40 - 4  may cover any desired bands at any desired frequencies (e.g., antenna  40 - 4  may exhibit any desired number of efficiency peaks extending over any desired frequency bands). Curves  146  and  144  may have other shapes if desired. 
     In this way, device  10  may be provided with a display  14  ( FIG. 1 ) having an active area AA that extends across substantially all of the front face of device  10 . Antenna  40 - 4  may be provided with satisfactory antenna efficiency across multiple frequency bands of interest despite the presence of the conductive display structures used to support such a large active area AA for display  14 . Antenna  40 - 4  may operate using a carrier aggregation scheme across one or more of these frequency bands and using a MIMO scheme with the other antennas in device  10  to maximize wireless data throughput for device  10 . 
     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: 20190619
Publication Date: 20201124
Grant Date: 20201124
Priority Date: 20190619
Inventors: AYALA VAZQUEZ, ENRIQUE
HU, HONGFEI
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/521", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/521", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/245", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/245", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 73464336