PATENT DOCUMENT

Publication Number: US-10164679-B1
Application Number: US-201715717367-A
Country: US
Kind Code: B1

Title: Electronic devices having multiple slot antennas

Abstract:
An electronic device may have conductive housing structures and first, second, third, and fourth slot antennas having respective first, second, third, and fourth slot elements in the conductive housing structures. The third slot element may be interposed between the first and second slot elements and the second slot element may be interposed between the third and fourth slot elements. Switching circuitry may be coupled between a transceiver and the slot elements. Control circuitry may control the switching circuitry to activate a selected pair of the slot antennas based on an orientation of the device or other data. The active pair of antennas may convey radio-frequency signals at the same frequencies using a multiple-input and multiple-output (MIMO) communications scheme. In this way, the device may perform wireless communications at relatively high data throughputs regardless of how the device is being held by a user.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a housing having conductive structures; 
 radio-frequency transceiver circuitry in the housing and having first and second ports; 
 a first slot antenna having a first slot element in the conductive structures and a first antenna feed coupled to the first port; 
 a second slot antenna having a second slot element in the conductive structures and a second antenna feed coupled to the first port; and 
 a third slot antenna having a third slot element in the conductive structures and a third antenna feed coupled to the second port, wherein at least some of the third slot element is interposed between the first and second slot elements. 
 
     
     
       2. The electronic device defined in  claim 1 , further comprising:
 a fourth slot antenna having a fourth slot element in the conductive structures and a fourth antenna feed coupled to the second port, wherein at least some of the second slot element is interposed between the third and fourth slot elements. 
 
     
     
       3. The electronic device defined in  claim 2 , further comprising:
 a first switch that is coupled between the first port and the first and second antenna feeds and that is configured to activate a selected one of the first and second slot antennas at a given time; and 
 a second switch that is coupled between the second port and the third and fourth antenna feeds and that is configured to activate a selected one of the third and fourth slot antennas at a given time. 
 
     
     
       4. The electronic device defined in  claim 3 , wherein the radio-frequency transceiver circuitry is configured to convey radio-frequency signals at a given frequency, the electronic device further comprising:
 control circuitry configured to control the first and second switches to convey the radio-frequency signals at the given frequency over a selected pair of the first, second, third, and fourth slot antennas under a multiple-input and multiple-output (MIMO) scheme. 
 
     
     
       5. The electronic device defined in  claim 3 , further comprising:
 an orientation sensor configured to generate orientation data indicative of an orientation of the electronic device; and 
 control circuitry configured to control the first and second switches to activate a selected pair of the first, second, third, and fourth slot antennas based on the orientation data. 
 
     
     
       6. The electronic device defined in  claim 5 , wherein the control circuitry is configured to adjust the first and second switches between a first state in which the third and second slot antennas are active and the first and fourth slot antennas are inactive, a second state in which the first and fourth slot antennas are active and the second and third slot antennas are inactive, a third state in which the first and third slot antennas are active and the second and fourth slot antennas are inactive, and a fourth state in which the second and fourth slot antennas are active and the first and third slot antennas are inactive. 
     
     
       7. The electronic device defined in  claim 6 , wherein the control circuitry is configured to place the first and second switches in:
 the first state in response to detecting that the electronic device is in a first orientation using the orientation data, 
 the second state in response to detecting that the electronic device is in a second orientation using the orientation data, 
 the third state in response to detecting that the electronic device is in a third orientation using the orientation data, and 
 the fourth state in response to detecting that the electronic device is in a fourth orientation using the orientation data. 
 
     
     
       8. The electronic device defined in  claim 2 , wherein the second and third slot elements comprise closed slots that are surrounded by the conductive structures and the first and fourth slot elements comprise open slots. 
     
     
       9. The electronic device defined in  claim 8 , wherein the conductive structures comprise peripheral sidewall structures and a planar rear wall structure that extends between the peripheral sidewall structures, the first slot element comprises a first dielectric-filled gap in a first portion of the peripheral sidewall structures, and the fourth slot element comprises a second dielectric-filled gap in a second portion of the peripheral sidewall structures. 
     
     
       10. The electronic device defined in  claim 9 , wherein the first and fourth slot elements each have a first elongated length and the second and third slot elements each have a second elongated length that is greater than the first elongated length. 
     
     
       11. The electronic device defined in  claim 9 , wherein the peripheral sidewall structures and the planar rear wall structure define at least some edges of each of the first, second, third, and fourth slot elements. 
     
     
       12. An electronic device comprising:
 conductive structures; 
 a first slot antenna having a first slot element in the conductive structures; 
 a second slot antenna having a second slot element in the conductive structures; 
 a third slot antenna having a third slot element in the conductive structures; 
 radio-frequency transceiver circuitry; 
 switching circuitry coupled between the radio-frequency transceiver circuitry and the first, second, and third slot elements; and 
 control circuitry configured to adjust the switching circuitry between a first mode in which the second antenna is active and the first and third antennas are inactive, a second mode in which the first and third antennas are active and the second antenna is inactive, a third mode in which the first antenna is active and the second and third antennas are inactive, and a fourth mode in which the second and third antennas are active and the first antenna is inactive. 
 
     
     
       13. The electronic device defined in  claim 12 , further comprising:
 a fourth slot antenna having a fourth slot element in the conductive structures, wherein the switching circuitry is coupled between the fourth slot element and the radio-frequency transceiver circuitry, the fourth antenna is active in the first and third modes, and the fourth antenna is inactive in the second and fourth modes. 
 
     
     
       14. The electronic device defined in  claim 13 , wherein the second slot element is interposed between the fourth and third slot elements and the fourth slot element is interposed between the first and second slot elements. 
     
     
       15. The electronic device defined in  claim 14 , wherein the first slot element includes a first segment that extends along a longitudinal axis, the third slot element includes a second segment that extends along the longitudinal axis, and the second and fourth slot elements each extend along the longitudinal axis. 
     
     
       16. The electronic device defined in  claim 13 , further comprising:
 a display that forms a front face for the electronic device, wherein the conductive structures comprise rear wall that forms a rear face for the electronic device and a plurality of peripheral conductive structures that extend between the rear wall and the display, and at least one edge of each of the first, second, third, and fourth slot elements is defined by a given one of the peripheral conductive structures in the plurality of peripheral conductive structures. 
 
     
     
       17. The electronic device defined in  claim 12 , further comprising:
 an orientation sensor that generates orientation data indicative of whether the electronic device is in first, second, third, or fourth orientations, wherein the control circuitry is configured to place the switching circuitry in:
 the first mode when the orientation data indicates that the electronic device is in the first orientation, 
 the second mode when the orientation data indicates that the electronic device is in the second orientation, 
 the third mode when the orientation data indicates that the electronic device is in the third orientation, and 
 the fourth mode when the orientation data indicates that the electronic device is in the fourth orientation. 
 
 
     
     
       18. The electronic device defined in  claim 12 , wherein the first, second, third, and fourth antennas are each configured to convey radio-frequency signals in the same frequency band. 
     
     
       19. An electronic device comprising:
 first, second, third, and fourth antennas having respective first, second, third, and fourth antenna resonating elements, wherein at least some of the second antenna resonating element is interposed between the first and third antenna resonating elements and at least some of the third antenna resonating element is interposed between the second and fourth antenna resonating elements; and 
 control circuitry configured to:
 identify an orientation of the electronic device, 
 activate the first and second antennas and deactivate the third and fourth antennas in response to identifying that the electronic device is in a first landscape orientation, and 
 activate the third and fourth antennas and deactivate the first and second antennas in response to identifying that the electronic device is in a second landscape orientation that is different from the first landscape orientation. 
 
 
     
     
       20. The electronic device defined in  claim 19 , wherein the control circuitry is further configured to:
 activate the second and third antennas and deactivate the first and fourth antennas in response to identifying that the electronic device is in a first portrait orientation; and 
 activate the first and fourth antennas and deactivate the second and third antennas in response to identifying that the electronic device is in a second portrait orientation that is different from the first portrait orientation.

Description:
BACKGROUND 
     This relates to electronic devices, and more particularly, to antennas for electronic devices with wireless communications circuitry. 
     Electronic devices such as portable computers and cellular telephones are often provided with wireless communications capabilities. 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. 
     Because antennas have the potential to interfere with each other and with components in a wireless device, care must be taken when incorporating antennas into an electronic device. Moreover, care must be taken to ensure that the antennas and wireless circuitry in a device are able to exhibit satisfactory performance over a range of operating frequencies and with a satisfactory efficiency bandwidth. In addition, in some devices a single antenna is used to cover a particular frequency band. However, in these scenarios, a single antenna may exhibit insufficient data throughput, particularly when handling communications for data-intensive device applications. 
     It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless electronic devices. 
     SUMMARY 
     An electronic device may have a housing with conductive housing structures. The conductive housing structures may include peripheral conductive structures and a conductive layer extending between the peripheral conductive structures. The conductive layer and/or the peripheral conductive structures may define edges of slot elements in one or more slot antennas. 
     The electronic device may include a radio-frequency transceiver having first and second ports. The first port may be coupled to a first antenna feed of a first slot antenna and a second antenna feed of a second slot antenna. The second port may be coupled to a third antenna feed of a third slot antenna and a fourth antenna feed of a fourth slot antenna. The first slot antenna may include a first slot element, the second slot antenna may include a second slot element, the third slot antenna may include a third slot element, and the fourth slot antenna may include a fourth slot element in the conductive housing structures. The third slot element may be interposed between the first and second slot elements whereas the second slot element may be interposed between the third and fourth slot elements. Switching circuitry may be coupled between the radio-frequency transceiver and each of the antenna feeds. 
     The electronic device may include an orientation sensor that generates orientation data indicative of an orientation of the electronic device. Control circuitry in the device may control the switching circuitry to activate a selected pair of the first, second, third, and fourth slot antennas at a given time based on the orientation data. The active pair of antennas may transmit and receive radio-frequency signals at the same frequencies under a multiple-input and multiple-output (MIMO) communications scheme. The control circuitry may control the switching circuitry to activate the second and third antennas when the device is in a portrait orientation, the first and fourth antennas when the device is in a reverse portrait orientation, the first and third antennas when the device is in a landscape orientation, and the second and fourth antennas when the device is in a reverse landscape orientation. In this way, the electronic device may perform wireless communications using a relatively high data throughput (e.g., using a MIMO scheme) regardless of how the device is being held by a user. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 3  is a diagram of illustrative wireless circuitry in an electronic device in accordance with an embodiment. 
         FIG. 4  is a diagram of illustrative slot antenna structures in accordance with an embodiment. 
         FIG. 5  is a top view of illustrative slot antennas in an electronic device in accordance with an embodiment. 
         FIG. 6  is a top view of illustrative slot antennas in an electronic device that can be switched into or out of use based on the orientation of the electronic device in accordance with an embodiment. 
         FIG. 7  is a flow chart of illustrative steps that may be involved in operating an electronic device having antennas of the type shown in  FIG. 6  in accordance with an embodiment. 
         FIG. 8  is a state diagram showing illustrative wireless operating modes for an electronic device with antennas of the type shown in  FIG. 6  in accordance with an embodiment. 
         FIGS. 9A-9D  are diagrams showing how different illustrative antennas may be activate in different device orientations in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may be provided with wireless circuitry that includes antennas. The antennas may be used to transmit and receive wireless signals. 
     The wireless circuitry of device  10  may handle one or more communications bands. For example, the wireless circuitry of device  10  may include a Global Position System (GPS) receiver that handles GPS satellite navigation system signals at 1575 MHz or a GLONASS receiver that handles GLONASS signals at 1609 MHz. Device  10  may also contain wireless communications circuitry that operates in communications bands such as cellular telephone bands and wireless circuitry that operates in communications bands such as the 2.4 GHz Bluetooth® band and the 2.4 GHz and 5 GHz WiFi® wireless local area network bands (sometimes referred to as IEEE 802.11 bands or wireless local area network communications bands). Device  10  may also contain wireless communications circuitry for implementing near-field communications at 13.56 MHz or other near-field communications frequencies. If desired, device  10  may include wireless communications circuitry for communicating at 60 GHz, circuitry for supporting light-based wireless communications, or other wireless communications. 
     Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14 . Display  14  may be mounted in 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. 
     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 substantially planar housing wall such as rear housing wall  12 R. Rear housing wall  12 R may have slots that pass entirely through the rear housing wall and that therefore separate portions of housing  12  from each other. Rear housing wall  12 R may include conductive portions and/or dielectric portions. If desired, rear housing wall  12 R may include a planar metal layer covered by a thin layer or coating of dielectric such as glass, plastic, sapphire, or ceramic. Housing  12  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). 
     Housing  12  may include peripheral housing structures such as peripheral structures  12 W. Peripheral structures  12 W and rear housing wall  12 R may sometimes be referred to herein collectively as conductive structures of housing  12 . Peripheral structures  12 W 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, peripheral structures  12 W may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges and that extend from rear housing wall  12 R to the front face of device  10  (as an example). Peripheral structures  12 W or part of peripheral structures  12 W 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 ) if desired. Peripheral structures  12 W 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  12 W 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 sidewalls, peripheral conductive sidewall structures, conductive housing sidewalls, peripheral conductive housing sidewalls, sidewalls, sidewall structures, or a peripheral conductive housing member (as examples). Peripheral conductive housing structures  12 W may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral conductive housing structures  12 W. 
     It is not necessary for peripheral conductive housing structures  12 W to have a uniform cross-section. For example, the top portion of peripheral conductive housing structures  12 W may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral conductive housing structures  12 W may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral conductive housing structures  12 W 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  12 W serve as a bezel for display  14 ), peripheral conductive housing structures  12 W may run around the lip of housing  12  (i.e., peripheral conductive housing structures  12 W may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, rear housing wall  12 R may be formed from a metal such as stainless steel or aluminum and may sometimes be referred to herein as conductive rear housing wall  12 R or conductive rear wall  12 R. Conductive rear housing wall  12 R may lie in a plane that is parallel to display  14 . In configurations for device  10  in which rear housing wall  12 R is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  12 W as integral portions of the housing structures forming the conductive rear housing wall of housing  12 . For example, conductive rear housing wall  12 R of device  10  may be formed from a planar metal structure and portions of peripheral conductive housing structures  12 W on the sides of housing  12  may be formed as flat or curved vertically extending integral metal portions of the planar metal structure (e.g., housing structures  12 R and  12 W may be formed from a continuous piece of metal in a unibody configuration). 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 . Conductive rear housing wall  12 R may have one or more, two or more, or three or more portions. Peripheral conductive housing structures  12 W and/or the conductive rear housing wall  12 R 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  12 W and/or  12 R from view of the user). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may have an active area AA that includes an array of display pixels. The array of pixels may be formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels or other light-emitting diode pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, transparent ceramic, sapphire, or other transparent crystalline material, or other transparent layer(s). The display cover layer may have a planar shape, a convex curved profile, a shape with planar and curved portions, a layout that includes a planar main area surrounded on one or more edges with a portion that is bent out of the plane of the planar main area, or other suitable shapes. The display cover layer may cover the entire front face of device  10 . In another suitable arrangement, the display cover layer may cover substantially all of the front face of device  10  or only a portion of the front face of device  10 . Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button. An opening may also be formed in the display cover layer to accommodate ports such as a speaker port or microphone port. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.) and/or audio ports for audio components such as a speaker and/or a microphone if desired. 
     Display  14  may have an inactive border region that runs along one or more of the edges of active area AA. Inactive area IA may be free of pixels for displaying images and may overlap circuitry and other internal device structures in housing  12 . To block these structures from view by a user of device  10 , the underside of the display cover layer or other layer in display  14  that overlaps inactive area IA may be coated with an opaque masking layer in inactive area IA. The opaque masking layer may have any suitable color. 
     The antennas of the wireless circuitry in device  10  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. 
     Portions of peripheral conductive housing structures  12 W may be provided with peripheral gap structures. For example, peripheral conductive housing structures  12 W may be provided with one or more peripheral gaps such as gaps  18 , as shown in  FIG. 1 . Gaps  18  in peripheral conductive housing structures  12 W may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials (e.g., gaps  18  may sometimes be referred to herein as dielectric gaps  18  or dielectric-filled gaps  18 ). Gaps  18  may divide peripheral conductive housing structures  12 W into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral housing structures  12 W (e.g., in an arrangement with two of gaps  18 ), three peripheral conductive segments (e.g., in an arrangement with three of gaps  18 ), four peripheral conductive segments (e.g., in an arrangement with four of gaps  18 ), etc. The segments of peripheral conductive housing structures  12 W 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 conductive rear housing wall  12 R and may penetrate through conductive rear housing wall  12 R to divide the conductive rear housing wall into different portions. These grooves may also extend into peripheral conductive housing structures  12 W 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. 
     Housing  12  may have four peripheral edges (e.g., four peripheral conductive sidewalls  12 W) as shown in  FIG. 1  and one or more antennas may be located along one or more of these edges. As shown in the illustrative configuration of  FIG. 1 , antennas may, if desired, be mounted in regions  20  along opposing peripheral edges of housing  12  (as an example). The antennas may include antenna resonating elements that emit and receive wireless signals through the front of device  10  (i.e., through inactive portions IA of display  14 ) and/or from the rear and sides of device  10 . In practice, active components within active display area AA may block or otherwise inhibit signal reception and transmission by the antennas. By placing the antennas within regions  20  of inactive area IA of display  14 , the antennas may freely pass signals through the display without the signals being blocked by active display circuitry. Antennas may also be mounted in other portions of device  10 , if desired. The configuration of  FIG. 1  is merely illustrative. 
     In order to provide an end user of device  10  with as large of a display as possible (e.g., to maximize an area of the device used for displaying media, running applications, etc.), it may be desirable to increase the amount of area at the front face of device  10  that is covered by active area AA of display  14 . Increasing the size of active area AA may reduce the size of inactive area IA within device  10 . This may reduce the area of regions  20  that is available for forming antennas within device  10 . In general, antennas that are provided with larger operating volumes or spaces may have higher bandwidth efficiency than antennas that are provided with smaller operating volumes or spaces. If care is not taken, increasing the size of active area AA may reduce the operating space available to the antennas, which can undesirably inhibit the efficiency bandwidth of the antennas (e.g., such that the antennas no longer exhibit satisfactory radio-frequency performance). It would therefore be desirable to be able to provide antennas that occupy a small amount of space within device  10  (e.g., to allow for as large of a display active area AA as possible) while still allowing the antennas to operate with optimal efficiency bandwidth. 
     A schematic diagram showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, multiple-input and multiple-output (MIMO) protocols, antenna diversity protocols, etc. 
     Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  32  may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, position and orientation sensors (e.g., sensors such as accelerometers, gyroscopes, and compasses), capacitance sensors, proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors, etc.), fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button  24  of  FIG. 1  or a fingerprint sensor that takes the place of button  24 ), etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . Transceiver circuitry  36  may handle wireless local area network (WLAN) bands such as 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and/or wireless personal area network (WPAN) bands such as the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a low-midband from 960 to 1710 MHz, a midband from 1710 to 2170 MHz, a high band from 2300 to 2700 MHz, an ultra-high band from 3400 to 3700 MHz and/or other communications bands between 600 MHz and 4000 MHz or other suitable frequencies (as examples). 
     Circuitry  38  may handle voice data and non-voice data. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Wireless communications circuitry  34  may include satellite navigation receive equipment such as global positioning system (GPS) receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., Global Navigation Satellite System (GLONASS) signals, etc.). In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, dipole antenna structures, monopole antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. 
     As shown in  FIG. 3 , transceiver circuitry  90  in wireless circuitry  34  may be coupled to antenna structures  40  using paths such as path  92 . Wireless circuitry  34  may be coupled to control circuitry  28 . Control circuitry  28  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures such as antenna(s)  40  with the ability to cover communications frequencies of interest, antenna(s)  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna(s)  40  may be provided with tuning circuits such as tuning components  101  to tune antennas over communications bands of interest. Tuning components  101  may be part of a filter or impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and antenna ground, etc. 
     Tuning components  101  may include fixed components (e.g., inductors having a fixed inductance, resistors having a fixed resistance, capacitors having a fixed capacitance, etc.) and/or may include tunable (adjustable) components such as tunable inductors, tunable capacitors, or other tunable components. Fixed tuning components  101  may include discrete components such as surface mount technology (SMT) capacitors, resistors, and/or inductors and/or may include distributed components such distributed capacitances, resistances, and/or inductances. Adjustable tuning components  101  components 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  93  that adjust inductance values, capacitance values, or other parameters associated with adjustable components in tuning components  101 , thereby tuning antenna structures  40  to cover desired communications bands. Fixed components in tuning components  101  may, for example, configure antennas  40  to cover one or more desired frequency bands of interest with satisfactory antenna efficiency using the same conductive structures. 
     Path  92  may include one or more transmission lines. As an example, signal path  92  of  FIG. 3  may be a transmission line having a positive signal conductor such as line  94  and a ground signal conductor such as line  96 . Path  92  may sometimes be referred to herein as radio-frequency transmission line  92  or transmission line  92 . Transmission line  92  may include a stripline transmission line, a microstrip transmission line, waveguide transmission lines, or other transmission line structures. Transmission lines in device  10  such as transmission line  92  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, transmission lines in device  10  may also include transmission line conductors (e.g., signal and ground conductors) 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) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that 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 tuning components  101 ) may include components such as inductors, resistors, and capacitors used in matching the impedance of antenna(s)  40  to the impedance of transmission line  92 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna(s)  40  and may be tunable and/or fixed components. 
     Transmission line  92  may be coupled to antenna feed structures associated with antenna structures  40 . As an example, antenna structures  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed  95  with a positive antenna feed terminal such as terminal  98  and a ground antenna feed terminal such as ground antenna feed terminal  100 . Positive transmission line conductor  94  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  96  may be coupled to ground antenna feed terminal  100 . Other types of antenna feed arrangements may be used if desired. For example, antenna structures  40  may be fed using multiple feeds. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Control circuitry  28  may use information from a proximity sensor (see, e.g., sensors  32  of  FIG. 2 ), wireless performance metric data such as received signal strength information, device orientation information from an orientation sensor, device motion data from an accelerometer or other motion detecting sensor, information about a usage scenario of device  10 , information about whether audio is being played through a speaker, information from one or more antenna impedance sensors, and/or other information in determining when antenna(s)  40  is being affected by the presence of nearby external objects or is otherwise in need of tuning. In response, control circuitry  28  may adjust an adjustable inductor, adjustable capacitor, switch, or other tunable component  101  and/or may switch one or more antennas  40  into or out of use to ensure that wireless communications circuitry  34  operates as desired. 
     The presence or absence of external objects such as a user&#39;s hand may affect antenna loading and therefore antenna performance. Antenna loading may differ depending on the way in which device  10  is being held. For example, antenna loading and therefore antenna performance may be affected in one way when a user is holding device  10  in a portrait orientation and may be affected in another way when a user is holding device  10  in a landscape orientation. To accommodate various loading scenarios, device  10  may use sensor data, antenna measurements, information about the usage scenario or operating state of device  10 , and/or other data from input-output circuitry  32  to monitor for the presence of antenna loading (e.g., the presence of a user&#39;s hand, the user&#39;s head, or another external object). Device  10  (e.g., control circuitry  28 ) may then adjust tunable components  101  in antenna  40  and/or may switch other antennas into or out of use to compensate for the loading (e.g., multiple antennas  40  may be operated using a diversity protocol to ensure that at least one antenna  40  may maintain satisfactory communications even while the other antennas are blocked by external objects). 
     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 any other antenna structures. In one suitable arrangement, antenna  40  may be formed using a slot antenna structure. An illustrative slot antenna structure that may be used for forming antenna  40  is shown in  FIG. 4 . As shown in  FIG. 4 , slot antenna  40  may include a conductive structure such as structure  102  that has been provided with a dielectric opening such as dielectric opening  104 . Openings such as opening  104  of  FIG. 4  are sometimes referred to as slots, slot elements, slot resonating elements, or slot antenna resonating elements of slot antenna  40 . In the configuration of  FIG. 4 , slot element  104  is a closed slot, because portions of conductive structure  102  completely surround and enclose slot element  104 . Open slot antennas may also be formed in conductive materials such as conductive structure  102  (e.g., by forming an opening in the right-hand or left-hand end of conductive structure  102  so that slot element  104  protrudes through conductive structure  102 ). 
     Antenna feed  95  for antenna  40  may be formed using positive antenna feed terminal  98  and ground antenna feed terminal  100 . In general, the frequency response of an antenna is related to the size and shapes of the conductive structures in the antenna. Slot antennas of the type shown in  FIG. 4  tend to exhibit response peaks when slot perimeter P is equal to the wavelength of operation of antenna  40  (e.g. where perimeter P is equal to two times length L plus two times width W). Antenna currents may flow between feed terminals  98  and  100  around perimeter P of slot element  104 . As an example, where slot length L&gt;&gt;slot width W, the length L of antenna  40  will tend to be about half of the length of other types of antennas such as inverted-F antennas configured to handle signals at the same frequencies. Given equal antenna volumes, slot antenna  40  will therefore be able to handle signals at approximately twice the frequency of other antennas such as inverted-F antennas, for example. 
     Feed  95  may be coupled across slot element  104  at a location along length L. For example, feed  95  may be located at a distance  105  from one side of slot element  104 . Distance  105  may be adjusted to match the impedance of antenna  40  to the impedance of the corresponding transmission line (e.g., transmission line  92  of  FIG. 3 ). For example, the antenna current flowing around slot element  104  may experience an impedance of zero at the left and right edges of slot element  104  (e.g., a short circuit impedance) and an infinite (open circuit) impedance at the center of slot element  104  (e.g., at a fundamental frequency of the slot). Location  105  may be located between the center of slot element  104  and the left edge at a location where the antenna current experiences an impedance that matches the impedance of the corresponding transmission line, for example (e.g., distance  105  may be between 0 and ¼% of the wavelength of operation of antenna  40 ). Distance  105  may, for example, be 9 mm, between 5 mm and 10 mm, between 2 mm and 12 mm, or any other suitable distance. Slot element  104  may have a width W perpendicular to length L. 
     In scenarios where slot element  104  is a closed slot, length L may be approximately equal to (e.g., within 15% of) one half of a wavelength of operation of antenna  40  (e.g., a wavelength of a fundamental mode of antenna  40 ). Harmonic modes of slot element  104  may also be configured to cover desired frequency bands. In scenarios where slot element  104  is an open slot, the length of slot element  104  may be approximately equal to one quarter of the wavelength of operation of antenna  40 . The wavelength of operation may, for example, be an effective wavelength of operation based on the dielectric material within slot element  104 . 
     The example of  FIG. 4  is merely illustrative. In general, slot element  104  may have any desired shape (e.g., where the perimeter P of slot element  104  defines resonant characteristics of antenna  40 ). For example, slot element  104  may have a meandering shape with different segments extending in different directions, may have straight and/or curved edges, etc. Conductive structure  102  may be formed from any desired conductive electronic device structures. For example, conductive structure  102  may include conductive traces on printed circuit boards or other substrates, sheet metal, metal foil, conductive structures associated with display  14  ( FIG. 1 ), conductive portions of housing  12  (e.g., conductive walls  12 W and/or  12 R of  FIG. 1 ), or other conductive structures within device  10 . In one suitable arrangement, different sides (edges) of slot element  104  may be defined by different conductive structures. 
     In the example of  FIG. 4 , a single slot antenna  40  is shown. 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 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 frequencies. 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 circuitry  34 . 
     A top interior view of an illustrative device  10  that contains multiple antennas  40  (e.g., for performing communications under a MIMO scheme) is shown in  FIG. 5 . As shown in  FIG. 5 , device  10  may have peripheral conductive housing structures such as peripheral conductive housing sidewalls  12 W. Peripheral conductive housing sidewalls  12 W may define a first (upper) edge  132 , a second (left) edge  134 , a third (lower) edge  136 , and a fourth (right) edge  130  of device  10  (in scenarios where device  10  has a substantially rectangular periphery). In the example of  FIG. 5 , display  14  is not shown for the sake of clarity. 
     Peripheral conductive housing sidewalls  12 W may be continuous or may be divided by dielectric-filled peripheral gaps (e.g., plastic gaps)  18  such as a first gap  18 - 1  in the peripheral conductive housing sidewall  12 W along edge  134  and a second gap  18 - 2  in the peripheral conductive housing sidewall  12 W along edge  130 . Gaps  18 - 1  and  18 - 2  may, for example, be formed within region  20  at the lower end of device  10  (e.g., under inactive region IA of display  14  as shown in  FIG. 1 ). Gaps  18 - 1  and  18 - 2  may be filled with plastic, ceramic, sapphire, glass, epoxy, or other dielectric materials. The dielectric material in gaps  18 - 1  and  18 - 2  may lie flush with peripheral conductive housing sidewalls  12 W at the exterior surface of device  10  if desired. 
     A conductive structure such as conductive layer  106  may extend between peripheral conductive housing sidewalls  12 W. Conductive layer  106  may be formed from conductive housing structures, conductive structures from electrical device components in device  10 , printed circuit board traces, strips of conductor such as strips of wire and metal foil, conductive components in a display (e.g., display  14  of  FIG. 1 ), and/or other conductive structures. In one suitable arrangement, conductive layer  106  is formed from the conductive rear wall of housing  12  (e.g., conductive rear housing wall  12 R as shown in  FIG. 1 ). 
     As shown in  FIG. 5 , conductive layer  106  (e.g., conductive rear housing wall  12 R) may extend between the opposing edges  134  and  130  and between opposing edges  132  and  136  of device  10 . Conductive layer  106  may be formed from a separate metal structure from peripheral conductive housing sidewalls  12 W or conductive layer  106  and peripheral conductive housing sidewalls  12 W may be formed from the same, continuous, integral metal structure (e.g., in a unibody configuration). An input-output device such as sensor components  120  may be formed adjacent to the corner of device  10  opposite to antenna  40 - 1  (e.g., at the upper-right corner of device  10  defined by the intersection of edges  132  and  130 ). Sensor components  120  may, for example, include one or more image sensors (e.g., cameras), one or more ambient light sensors, one or more infrared sensors (e.g., infrared proximity sensors), and/or other sensor components. Components  120  may include light emitting components such as camera flash components, infrared emitters, or other light emitters if desired. Components  120  may be positioned within housing  12  at a location (e.g., a location adjacent to the upper-right corner of device  10  defined by edges  132  and  130 ) such that components  120  are unlikely to be covered by a user&#39;s hands when the user is holding device  10  in a portrait orientation (e.g., with edge  132  pointing upwards or away from the user and edge  136  pointing towards the user or towards the ground). Components  120  may emit light and/or receive light through the rear surface of device  10  (e.g., through a window or opening in conductive layer  106  or conductive rear housing wall  12 R). This example is merely illustrative. If desired, components  120  may be formed at other locations along edge  132  (e.g., at the upper-left corner of device  10 ) or at any other desired location along the conductive rear housing wall. 
     In the example of  FIG. 5 , a first slot antenna  40 - 1  and a second slot antenna  40 - 2  are formed in conductive layer  106  and peripheral conductive housing sidewalls  12 W (e.g., conductive layer  106  and peripheral conductive housing sidewalls  12 W may form conductive structures  102  of  FIG. 4 ). Slot antenna  40 - 1  may include a corresponding slot element  104 - 1  in conductive layer  106 . Slot element  104 - 1  may be filled with plastic, glass, sapphire, epoxy, ceramic, or other dielectric material. Slot element  104 - 1  may be continuous with peripheral gap  18 - 1  in peripheral conductive housing sidewalls  12 W (e.g., a single piece of dielectric material may be used to fill both slot element  104 - 1  and gap  18 - 1 ). Slot element  104 - 1  may have a closed end  140 - 1  defined by conductive layer  106  and may extend to an opposing open end formed by peripheral gap  18 - 1  in peripheral conductive housing sidewalls  12 W (e.g., slot antenna  40 - 1  may be an open slot antenna and element  104 - 1  may be an open slot element defined by conductive structures  106  and  12 W). 
     Antenna  40 - 1  may be fed using a corresponding antenna feed  95 - 1  coupled across slot element  104 - 1 . Antenna feed  95 - 1  may be coupled to a corresponding port P 1  of transceiver circuitry  90  over a corresponding radio-frequency transmission line  92 - 1 . The frequency response of open slot antenna  40 - 1  may be determined by the elongated length L 1  of slot element  104 - 1  and gap  18 - 1  (e.g., length L 1  may include the vertical height of gap  18 - 1  extending up the vertical height of peripheral conductive housing sidewalls  12 W from conductive rear housing wall  12 R to display  14  as shown by gap  18  in  FIG. 1 ). Length L 1  may be approximately equal to one quarter of the wavelength of operation of antenna  40 - 1 , for example. 
     In the example of  FIG. 5 , slot element  104 - 1  has a meandering shape with a first segment coupled to feed  95 - 1 , a second segment extending from an end of the first segment and perpendicular to the first segment, and a third segment extending from an end of the second segment to gap  18 - 1  approximately parallel to the first segment. This is merely illustrative. In general, slot element  104 - 1  may be straight or may have any desired shape having any desired number of segments and straight and/or curved edges. 
     Slot antenna  40 - 2  may include a corresponding slot element  104 - 2  in conductive layer  106 . Slot element  104 - 2  may be filled with plastic, glass, sapphire, epoxy, ceramic, or other dielectric material. Slot element  104 - 2  may be continuous with peripheral gap  18 - 2  in peripheral conductive housing sidewalls  12 W (e.g., a single piece of dielectric material may be used to fill both slot element  104 - 2  and gap  18 - 2 ). Slot element  104 - 2  may have a closed end  140 - 2  defined by conductive layer  106  and may extend to an opposing open end formed by peripheral gap  18 - 2  in peripheral conductive housing sidewall  12 W (e.g., slot antenna  40 - 2  may be an open slot antenna and element  104 - 2  may be an open slot element defined by conductive structures  106  and  12 W). 
     Antenna  40 - 2  may be fed using a corresponding antenna feed  95 - 2  coupled across slot  104 - 2 . Antenna feed  95 - 2  may be coupled to a corresponding port P 2  of transceiver circuitry  90  over a corresponding radio-frequency transmission line  92 - 2 . The frequency response of open slot antenna  40 - 2  may be determined by the elongated length L 1  of slot element  104 - 2  and gap  18 - 2  (e.g., length L 1  may include the vertical height of gap  18 - 2  extending up the vertical height of peripheral conductive housing sidewall  12 W from conductive rear housing wall  12 R to display  14  as shown by gap  18  in  FIG. 1 ). Length L 1  may be approximately equal to one quarter of the wavelength of operation of antenna  40 - 2 , for example. 
     In the example of  FIG. 5 , slot element  104 - 2  has a meandering shape with a first segment coupled to feed  95 - 2 , a second segment extending from an end of the first segment and perpendicular to the first segment, and a third segment extending from an end of the second segment to gap  18 - 2  approximately parallel to the first segment. This is merely illustrative. In general, slot element  104 - 2  may be straight or may have any desired shape having any desired number of segments and straight and/or curved edges. 
     In order to enhance the data throughput of wireless circuitry  34 , transceiver circuitry  90  may perform communications under a MIMO scheme using antennas  40 - 1  and  40 - 2 . In order to perform MIMO communications, transceiver  90  may convey radio-frequency signals at the same frequencies (e.g., in the same frequency band) over antennas  40 - 1  and  40 - 2 . Because antennas  40 - 1  and  40 - 2  need to cover the same frequencies, the size and shape of slot element  104 - 1  and gap  18 - 1  may be the same as the size and shape of slot element  104 - 2  and gap  18 - 2  (e.g., both antennas  40 - 1  and  40 - 2  may be characterized by elongated length L 1 ). In one suitable arrangement, transceiver circuitry  90  may include wireless local area network transceiver circuitry  36  ( FIG. 2 ) having ports P 1  and P 2  for performing MIMO operations. 
     The example of  FIG. 5  is merely illustrative. The edges of slot elements  104 - 1  and  104 - 2  may be defined by conductive layer  106  and/or portions of one or more peripheral conductive housing sidewalls  12 W. For example, the lower edges of slot element  104 - 1  (e.g., the edges coupled to the positive feed terminal of the corresponding antenna feed  95 ) may be defined by a portion of the peripheral conductive housing sidewall  12 W at edge  136  of device  10  and a portion of the peripheral conductive housing sidewall  12 W at edge  134  of device  10 . Similarly, the lower edges of slot element  104 - 2  may be defined by a portion of the peripheral conductive housing sidewall  12 W at edge  136  and a portion of the peripheral conductive housing sidewall  12 W at edge  130 . In another suitable arrangement, one or more of the edges of slot elements  104 - 1  and  104 - 2  may be defined by a curved portion of housing  12  where peripheral conductive housing sidewalls  12 W join with conductive layer  106  (e.g., in scenarios where peripheral conductive housing sidewalls  12 W and conductive rear housing wall  12 R are formed from a single continuous piece of metal in a unibody configuration). If desired, the positions of the positive and ground feed terminals in one or both of feeds  95 - 1  and  95 - 2  may be swapped. Device  10  need not have a substantially rectangular periphery and may, if desired, have other shapes. 
     When configured in this way, transceiver circuitry  90  may convey wireless signals at the same frequencies using both antennas  40 - 1  and  40 - 2  (e.g., under a MIMO scheme) with a greater data throughput than in scenarios where only one of antennas  40  are used. However, if care is not taken, antennas  40 - 1  and  40 - 2  may be susceptible to loading by external objects such as a user&#39;s hands. For example, if a user is holding device  10  in a portrait orientation, the user&#39;s hands may cover one or both of antennas  40 - 1  and  40 - 2 . The user&#39;s hands may load antennas  40 - 1  and  40 - 2 , causing antennas  40 - 1  and  40 - 2  to become detuned and/or to exhibit deteriorated antenna efficiency. This may generate errors in the conveyed wireless data, may cause wireless circuitry  34  to lose MIMO functionality (e.g., if only one of antennas  40 - 1  and  40 - 2  is operating properly, wireless circuitry  34  will be incapable of achieving the high data throughput associated with MIMO operations), and/or may cause the corresponding wireless connection to be dropped. 
     In another possible arrangement, antennas  40 - 1  and  40 - 2  may be formed using closed slots located within layer  106  (e.g., at locations between ends  140 - 1  and  140 - 2  as shown in  FIG. 5 ). However, in these scenarios, if a user is holding device  10  in a landscape orientation, the user&#39;s hands may still cover one or both of the antennas, causing the covered antenna to become detuned and/or to exhibit deteriorated antenna efficiency and thereby preventing the performance of satisfactory MIMO communications. 
       FIG. 6  is a top interior view of device  10  showing how device  10  may be configured to maintain MIMO operations regardless of how the user is holding device  10 . As shown in  FIG. 6 , additional slot antennas  40  such as slot antennas  40 - 3  and  40 - 4  may be formed in conductive layer  106 . Slot antenna  40 - 3  may include a corresponding slot element  104 - 3  in conductive layer  106 . Slot element  104 - 3  may be filled with plastic, glass, sapphire, epoxy, ceramic, or other dielectric material. The dielectric material in slot element  104 - 2  may, for example, lie flush with layer  106  and/or the exterior surface(s) of device  10 . Slot element  104 - 3  may be a closed slot having elongated length L 2  extending between opposing closed ends of slot element  104 - 3  (e.g., slot antenna  40 - 3  may be a closed slot antenna). 
     Antenna  40 - 3  may be fed using a corresponding antenna feed  95 - 3  coupled across slot element  104 - 3 . Antenna feed  95 - 3  may be coupled to a corresponding radio-frequency transmission line  92 - 3 . The frequency response of closed slot antenna  40 - 3  may be determined by the elongated length L 2  of slot element  104 - 3 . Length L 2  may be approximately equal to one half of the wavelength of operation of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  (e.g., length L 2  may be approximately twice length L 1 ). If desired, a harmonic mode of slot element  104 - 3  may be used to cover the same frequencies as the fundamental mode of slots elements  104 - 1  and  104 - 2  (e.g., for performing MIMO communications at the same frequencies as antennas  40 - 1  and  40 - 2 ). 
     In the example of  FIG. 6 , slot element  104 - 3  has a straight shape. This is merely illustrative. In general, slot element  104 - 3  may follow a meandering path or may have any desired shape having any desired number of segments and straight and/or curved edges. Each of the edges of slot element  104 - 3  may be defined by conductive layer  106  and/or portions of the peripheral conductive housing sidewall  12 W at edge  136  of device  10 . For example, the lower edge of slot element  104 - 3  (e.g., the edge coupled to the positive feed terminal of antenna feed  95 - 3 ) may be defined by a portion of the peripheral conductive housing sidewall  12 W at edge  136  of device  10 . In another suitable arrangement, one or more of the edges of slot element  104 - 3  may be defined by a curved portion of housing  12  where peripheral conductive housing sidewall  12 W joins with conductive layer  106  (e.g., in scenarios where peripheral conductive housing sidewalls  12 W and conductive rear housing wall  12 R are formed from a single continuous piece of metal in a unibody configuration). If desired, the positions of the positive and ground feed terminals of feed  95 - 3  may be swapped. 
     Slot antenna  40 - 4  may include a corresponding slot element  104 - 4  in conductive layer  106 . Slot element  104 - 4  may be filled with plastic, glass, sapphire, epoxy, ceramic, or other dielectric material. The dielectric material in slot element  104 - 4  may lie flush with layer  106  and/or the exterior surface(s) of device  10 . Slot element  104 - 4  may be a closed slot having elongated length L 2  extending between opposing closed ends of slot element  104 - 4  (e.g., slot antenna  40 - 4  may be a closed slot antenna having the same length, shape, and/or dimensions as slot  104 - 3  in antenna  40 - 3 ). 
     Antenna  40 - 4  may be fed using a corresponding antenna feed  95 - 4  coupled across slot element  104 - 4 . Antenna feed  95 - 4  may be coupled to a corresponding radio-frequency transmission line  92 - 4 . A harmonic mode of slot element  104 - 4  may be used to cover the same frequencies as the fundamental mode of slot elements  104 - 1  and  104 - 2  and the harmonic mode of slot element  104 - 3  (e.g., for performing MIMO communications at the same frequencies as antennas  40 - 1 ,  40 - 2 , and  40 - 3 ). 
     In the example of  FIG. 6 , slot element  104 - 4  has a straight shape. This is merely illustrative. In general, slot element  104 - 4  may follow a meandering path or may have any desired shape having any desired number of segments and straight and/or curved edges. Each of the edges of slot element  104 - 4  may be defined by conductive layer  106  and/or portions of the peripheral conductive housing sidewall  12 W at edge  136  of device  10 . For example, the lower edge of slot element  104 - 4  (e.g., the edge coupled to the positive feed terminal of antenna feed  95 - 4 ) may be defined by a portion of the peripheral conductive housing sidewall  12 W at edge  136  of device  10 . In another suitable arrangement, one or more of the edges of slot element  104 - 4  may be defined by a curved portion of housing  12  where peripheral conductive housing sidewall  12 W joins with conductive layer  106  (e.g., in scenarios where peripheral conductive housing sidewalls  12 W and conductive rear housing wall  12 R are formed from a single continuous piece of metal in a unibody configuration). If desired, the positions of the positive and ground feed terminals of feed  95 - 4  may be swapped. 
     As shown in  FIG. 6 , the longitudinal axis of slot element  104 - 3  is aligned with the longitudinal axis of slot element  104 - 4 . The longitudinal axis of slot elements  104 - 3  and  104 - 4  may be aligned with the longitudinal axis of the segment of slot element  104 - 1  extending from closed end  140 - 1 . The longitudinal axis of slot elements  104 - 3  and  104 - 4  may be aligned with the longitudinal axis of the segment of slot element  104 - 2  extending from closed end  140 - 2 . Slot element  104 - 3  may be interposed between slot element  104 - 1  and slot element  104 - 4 . Slot element  104 - 4  may be interposed between slot element  104 - 3  and slot element  104 - 2 . Each of slot elements  104 - 1 ,  104 - 2 ,  104 - 3 , and  104 - 4  may be formed within region  20  at the lower end of device  10  (e.g., under inactive area IA of display  14  as shown in  FIG. 1 ). 
     Aligning slot elements  104 - 1 ,  104 - 2 ,  104 - 3 , and  104 - 4  in this way may allow for the size of inactive area IA to be minimized without blocking antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4 , for example. If desired, each slot element  104  may have the same width (e.g., width W of  FIG. 4 ) or two or more slot elements  104  may have different widths. In order to ensure that antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  are not blocked by conductive circuitry in display  14 , the width of slot elements  104  may, for example, be limited by the size of inactive area IA of display  14 . As examples, the widths of slot elements  104  may be approximately 0.9 mm, between 0.5 mm and 1.5 mm, between 0.7 mm and 1.2 mm, etc. Decreasing the size of inactive area IA (and thus width W) may maximize the size of active area AA on display  14  for a user of device  10 , for example. 
     Transceiver  90  may perform MIMO operations at the same frequencies using a selected pair of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  at a given time. The pair of antennas that is selected (active) at a given time may be controlled by adjusting switching circuitry such as first radio-frequency switch  150  and second radio-frequency switch  152 . Switches  150  and  152  may sometimes be referred to herein as switching circuits. Control circuitry  28  ( FIG. 2 ) may provide control signals to control the state of switches  150  and  152  to activate a selected pair of antennas at a given time. 
     As shown in  FIG. 6 , switch  150  may have a first switch port (switch terminal) T 1  coupled to port P 1  of transceiver circuitry  90  over radio-frequency transmission line  92 -P 1 . Switch  150  may have a second switch port T 2  coupled to feed  95 - 1  of antenna  40 - 1  over radio-frequency transmission line  92 - 1 . Switch  150  may have a third switch port T 3  coupled to feed  95 - 4  of antenna  40 - 4  over radio-frequency transmission line  92 - 4 . Switch  150  may, for example, be a single-pole double-throw (SP2T) switch having a first state at which switch port T 1  is coupled (shorted) to switch port T 2  and a second state at which switch port T 1  is coupled to switch port T 3 . This is merely illustrative and, in general, any desired switching circuitry may be used in implementing switch  150 . 
     In the first state of switch  150 , port P 1  of transceiver  90  may convey radio-frequency signals over antenna  40 - 1  (e.g., antenna  40 - 1  may be active or enabled while antenna  40 - 4  is inactive or disabled). In the second state of switch  150 , port P 1  of transceiver  90  may convey radio-frequency signals over antenna  40 - 4  (e.g., antenna  40 - 4  may be active or enabled while antenna  40 - 1  is inactive or disabled). Control circuitry  28  may provide control signals that place switch  150  in one of these first or second switch states at a given time. 
     Switch  152  may have a first switch port (switch terminal) T 4  coupled to port P 2  of transceiver circuitry  90  over radio-frequency transmission line  92 -P 2 . Switch  152  may have a second switch port T 5  coupled to feed  95 - 3  of antenna  40 - 3  over radio-frequency transmission line  92 - 3 . Switch  152  may have a third switch port T 6  coupled to feed  95 - 2  of antenna  40 - 2  over radio-frequency transmission line  92 - 2 . Switch  152  may, for example, be a single-pole double-throw (SP2T) switch having a first state at which switch port T 4  is coupled (shorted) to switch port T 5  and a second state at which switch port T 4  is coupled to switch port T 6 . This is merely illustrative and, in general, any desired switching circuitry may be used in implementing switch  152 . 
     In the first state of switch  152 , port P 2  of transceiver circuitry  90  may convey radio-frequency signals over antenna  40 - 3  (e.g., antenna  40 - 3  may be active or enabled while antenna  40 - 2  is inactive or disabled). In the second state of switch  152 , port P 2  of transceiver circuitry  90  may convey radio-frequency signals over antenna  40 - 2  (e.g., antenna  40 - 2  may be active or enabled while antenna  40 - 3  is inactive or disabled). Control circuitry  28  may provide control signals that place switch  152  in one of these first or second switch states at a given time. 
     Control circuitry  28  may control switches  150  and  152  to place wireless circuitry  34  in one of four different operating states or modes during which different pairs of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  are active at a given time. Control circuitry  28  may select which pair of antennas are active for MIMO communications based on any desired data. The pair of selected (active) antennas may, for example, be the pair of antennas that is least likely to be loaded by a user&#39;s hands at any given time while the user is holding device  10 . 
     The example of  FIG. 6  is merely illustrative. In general, antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may be formed at any desired locations within device  10 . Antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  need not be slot antennas and may, in general, be formed using any desired antenna structures (e.g., where the antenna resonating element of the antenna  40 - 2  is interposed between the antenna resonating elements of antennas  40 - 1  and  40 - 3 , the antenna resonating element of antenna  40 - 3  is interposed between the antenna resonating elements of antennas  40 - 2  and  40 - 4 , and the antenna resonating element is coupled to the positive feed terminal in the corresponding feed  95 ). Slot elements  104 - 1 ,  104 - 2 ,  104 - 3 , and  104 - 4  may have any desired shapes and relative orientations. In the example of  FIG. 6 , slot elements  104 - 1 ,  104 - 2 ,  104 - 3 , and  104 - 4  are configured to cover a single frequency band (e.g., a wireless local area network frequency band). However, if desired, slot elements  104 - 1 ,  104 - 2 ,  104 - 3 , and/or  104 - 4  may have multiple branches and/or filter circuitry for covering multiple different frequency bands. 
     To ensure that wireless circuitry  34  operates satisfactorily regardless of how the user is holding device  10 , control circuitry in device  10  (e.g., control circuitry  28  as shown in  FIGS. 2 and 3 ) may determine which type of device operating environment is present and may adjust switches  150  and  152  (sometimes referred to collectively herein as switching circuitry) to selectively activate an optimal pair of antennas  40  to compensate.  FIG. 7  is a flow chart of illustrative steps involved in operating device  10  to ensure satisfactory performance for wireless circuitry  34  regardless of how a user is holding device  10 . 
     At step  160  of  FIG. 7 , control circuitry  28  may monitor the operating environment of device  10 . 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 inertial sensor (e.g., accelerometer), gyroscope, and/or compass in device  10  to help determine whether device  10  is being held in a portrait orientation (e.g., an orientation at which edge  132  of device  10  as shown in  FIG. 6  points upwards or away from the user), a reverse portrait orientation (e.g., an orientation at which edge  132  points towards the ground or towards the user), a landscape orientation (e.g., an orientation at which edge  130  points towards the ground or towards the user), or a reverse landscape orientation (e.g., an orientation at which edge  130  points upwards or away from the user). A user may be statistically likely to be holding device  10  in a particular manner (e.g., with the user&#39;s hands nearby to corresponding antennas  40 ) based on the present orientation of device  10 . This information may be used to predict which antennas are likely to be loaded and thus detuned by the presence of the user&#39;s hands, for example. 
     If desired, 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 particular speakers of device  10 , information identifying whether a telephone call is being conducted, information identifying whether a microphone on device  10  is receiving voice signals, etc.). 
     If desired, impedance sensors or other sensors may be used in monitoring the impedance of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4 . Different antenna loading scenarios may load antenna  40  differently, so impedance measurements may help determine whether device  10  is being gripped in a manner that causes one or more of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , or  40 - 4  to be loaded and detuned by the user&#39;s hand. Another way in which control circuitry  28  may monitor antenna loading conditions involves making received signal strength measurements or other wireless performance metric measurements (e.g., error rate measurements, signal to noise ratio measurements, noise measurements, etc.) on radio-frequency signals being received with each of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4 . 
     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 ). Such information may be indicative of the present operating conditions of device  10  (e.g., gathered data indicative of which antennas are currently being loaded and detuned by a user&#39;s hands) and/or may be predictive of which antennas are likely to be loaded and detuned by a user&#39;s hands. 
     At step  162 , control circuitry  28  may select an optimal pair of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  to be active (e.g., for performing MIMO communications) based on the current operating environment of device  10  (e.g., based on data or information gathered while processing step  160 ). For example, control circuitry  28  may process the data gathered while processing step  160  to determine whether device  10  is being held in a portrait orientation, a reverse portrait orientation, a landscape orientation, or a reverse landscape orientation, or whether device  10  is being held in a particular manner in which one or more of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  are being loaded and thus detuned by external objects such as the user&#39;s hands. 
     For example, if control circuitry  28  determines that device  10  is being held in a portrait orientation or that a first set of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  is being loaded or detuned, control circuitry  28  may select (activate) a first pair of the antennas for performing MIMO communications. If control circuitry  28  determines that device  10  is being held in a reverse portrait orientation or that a second set of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  is being loaded or detuned, control circuitry  28  may select (activate) a second pair of the antennas for performing MIMO communications. If control circuitry  28  determines that device  10  is being held in a landscape orientation or that a third set of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  is being loaded or detuned, control circuitry  28  may select (activate) a third pair of the antennas for performing MIMO communications. If control circuitry  28  determines that device  10  is being held in a reverse landscape orientation or that a fourth set of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  is being loaded or detuned, control circuitry  28  may select (activate) a fourth pair of the antennas for performing MIMO communications. Control circuitry  28  may adjust switches  150  and  152  to couple the selected antennas to the corresponding port of transceiver circuitry  90  ( FIG. 6 ). If desired, control circuitry  28  may further adjust tuning components (e.g., tuning components  101  of  FIG. 3 ) to tweak the frequency response of the selected antennas based on the data gathered while processing step  160 . 
     At step  164 , the selected pair of antennas may be used to transmit and receive wireless data using a MIMO communications scheme. This process may be performed continuously, as indicated by line  166 . 
     A state diagram showing illustrative operating modes for wireless communications circuitry  34  is shown in  FIG. 8 . As shown in  FIG. 8 , wireless communications circuitry  34  may be operable in at least first, second, third, and fourth operating modes (states). 
     In the first mode  180  (sometimes referred to herein as portrait mode  180  or portrait state  180 ), antennas  40 - 3  and  40 - 4  may be active and antennas  40 - 1  and  40 - 2  may be inactive. Control circuitry  28  may control switch  152  ( FIG. 6 ) to couple switch port T 4  to switch port T 5  and may control switch  150  to couple switch port T 1  to switch port T 3  to activate (select) antennas  40 - 3  and  40 - 4  (e.g., while processing step  162  of  FIG. 7 ). Antennas  40 - 1  and  40 - 2  may be decoupled from transceiver circuitry  90  in mode  180 . Antennas  40 - 3  and  40 - 4  may subsequently transmit and receive wireless signals in the same frequency band using a MIMO scheme (e.g., while processing step  164  of  FIG. 7 ). Control circuitry  28  may place wireless communications circuitry  34  in first mode  180  in response to determining that one or both of antennas  40 - 1  and  40 - 2  is being loaded or detuned by external objects and/or in response to determining that device  10  is being held in the portrait orientation, for example. 
     In the second mode  182  (sometimes referred to herein as reverse portrait mode  182  or reverse portrait state  182 ), antennas  40 - 1  and  40 - 2  may be active and antennas  40 - 3  and  40 - 4  may be inactive. Control circuitry  28  may control switch  152  to couple switch port T 4  to switch port T 6  and may control switch  150  to couple switch port T 1  to switch port T 2  to activate (select) antennas  40 - 1  and  40 - 2  (e.g., while processing step  162  of  FIG. 7 ). Antennas  40 - 3  and  40 - 4  may be decoupled from transceiver circuitry  90  in mode  182 . Antennas  40 - 1  and  40 - 2  may subsequently transmit and receive wireless signals in the same frequency band using a MIMO scheme (e.g., while processing step  164  of  FIG. 7 ). Control circuitry  28  may place wireless communications circuitry  34  in second mode  182  in response to determining that one or both of antennas  40 - 3  and  40 - 4  is being loaded or detuned by external objects, in response to determining that none of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  is being loaded or detuned by external objects (e.g., state  182  may be a default or free space state for circuitry  34 ), and/or in response to determining that device  10  is being held in the reverse portrait orientation, for example. 
     In the third mode  184  (sometimes referred to herein as landscape mode  184  or landscape state  184 ), antennas  40 - 1  and  40 - 3  may be active and antennas  40 - 2  and  40 - 4  may be inactive. Control circuitry  28  may control switch  152  to couple switch port T 4  to switch port T 5  and may control switch  150  to couple switch port T 1  to switch port T 2  to activate (select) antennas  40 - 1  and  40 - 3  (e.g., while processing step  162  of  FIG. 7 ). Antennas  40 - 2  and  40 - 4  may be decoupled from transceiver circuitry  90  in mode  184 . Antennas  40 - 1  and  40 - 3  may subsequently transmit and receive wireless signals in the same frequency band using a MIMO scheme (e.g., while processing step  164  of  FIG. 7 ). Control circuitry  28  may place wireless communications circuitry  34  in third mode  184  in response to determining that one or both of antennas  40 - 4  and  40 - 2  is being loaded or detuned by external objects and/or in response to determining that device  10  is being held in the landscape orientation, for example. 
     In the fourth mode  186  (sometimes referred to herein as reverse landscape mode  186  or reverse landscape state  186 ), antennas  40 - 2  and  40 - 4  may be active and antennas  40 - 1  and  40 - 3  may be inactive. Control circuitry  28  may control switch  152  to couple switch port T 4  to switch port T 6  and may control switch  150  to couple switch port T 1  to switch port T 3  to activate (select) antennas  40 - 2  and  40 - 4  (e.g., while processing step  162  of  FIG. 7 ). Antennas  40 - 1  and  40 - 3  may be decoupled from transceiver circuitry  90  in mode  186 . Antennas  40 - 2  and  40 - 4  may subsequently transmit and receive wireless signals in the same frequency band using a MIMO scheme (e.g., while processing step  164  of  FIG. 7 ). Control circuitry  28  may place wireless communications circuitry  34  in fourth mode  186  in response to determining that one or both of antennas  40 - 1  and  40 - 3  is being loaded or detuned by external objects and/or in response to determining that device  10  is being held in the reverse landscape orientation, for example. Control circuitry  28  may identify which mode is to be used based on the monitored operating environment of device  10  (e.g., using the sensor data and other information gathered while processing step  160  of  FIG. 7 ) and may adjust switches  150  and  152  of  FIG. 6  to place wireless circuitry  34  in the corresponding operating mode. 
       FIGS. 9A-9D  are diagrams showing how device  10  may be operated in each of modes  180 ,  182 ,  184 , and  186  of  FIG. 8 . As shown in  FIG. 9A , when device  10  is held in a portrait orientation, the user&#39;s body (e.g., left hand  190  and/or right hand  192 ) may be statistically likely to hold the bottom-left and bottom-right corners of device  10 . When held in this orientation (e.g., with lower edge  136  of device  10  pointing downwards or towards the user and sensor  120  pointed away from the user&#39;s body or towards the ground), left hand  190  may load and detune antenna  40 - 1  and right hand  192  may load and detune antenna  40 - 2  ( FIG. 6 ). However, antennas  40 - 3  and  40 - 4  may be sufficiently far from hands  190  and  192  so as to not be significantly loaded or detuned by hands  190  and  192 . Control circuitry  28  may subsequently place device  10  in portrait mode  180  of  FIG. 8 . In this mode, antennas  40 - 3  and  40 - 4  may both convey radio-frequency signals in the same frequency band under a MIMO scheme (e.g., without being impacted by hands  190  or  192 ). 
     As shown in  FIG. 9B , when device  10  is held in a reverse portrait orientation, left hand  190  and/or right hand  192  may be statistically likely to hold the top-right and top-left corners of device  10 , respectively. When held in this orientation (e.g., with lower edge  136  of device  10  pointing upwards or away from the user and sensor  120  located next to hand  190  and pointed away from the user or towards the ground), antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  may be sufficiently far from hands  190  and  192  so as to not be significantly loaded or detuned by hands  190  and  192 . Control circuitry  28  may subsequently place device  10  in reverse portrait mode  182  of  FIG. 8 . In this mode, antennas  40 - 1  and  40 - 2  may both convey radio-frequency signals in the same frequency band under a MIMO scheme (e.g., without being impacted by hands  190  or  192 ). Antennas  40 - 1  and  40 - 2  are located farther apart than antennas  40 - 3  and  40 - 4  and may offer a greater degree of spatial diversity than antennas  40 - 3  and  40 - 4 , for example. 
     As shown in  FIG. 9C , when device  10  is held in a landscape orientation, left hand  190  and/or right hand  192  may be statistically likely to hold the bottom-right and top-right corners of device  10 , respectively. When held in this orientation (e.g., with edge  136  of device  10  pointing towards the left and conductive rear housing wall  12 R pointing towards the ground or away from the user&#39;s body), left hand  190  may load and detune antenna  40 - 2  and/or antenna  40 - 4 . However, antennas  40 - 1  and  40 - 3  may be sufficiently far from hands  190  and  192  so as to not be significantly loaded or detuned by hands  190  and  192 . Control circuitry  28  may subsequently place device  10  in landscape mode  184  of  FIG. 8 . In this mode, antennas  40 - 1  and  40 - 3  may both convey radio-frequency signals in the same frequency band under a MIMO scheme (e.g., without being impacted by hands  190  or  192 ). 
     As shown in  FIG. 9D , when device  10  is held in a reverse landscape orientation, left hand  190  and/or right hand  192  may be statistically likely to hold the top-left and bottom-left corners of device  10 , respectively. When held in this orientation (e.g., with edge  136  of device  10  pointing towards the right and conductive rear housing wall  12 R pointing towards the ground or away from the user&#39;s body), right hand  192  may load and detune antenna  40 - 1  and/or antenna  40 - 3 . However, antennas  40 - 2  and  40 - 4  may be sufficiently far from hands  190  and  192  so as to not be significantly loaded or detuned by hands  190  and  192 . Control circuitry  28  may subsequently place device  10  in reverse landscape mode  186  of  FIG. 8 . In this mode, antennas  40 - 4  and  40 - 2  may both convey radio-frequency signals in the same frequency band under a MIMO scheme (e.g., without being impacted by hands  190  or  192 ). 
     The examples of  FIGS. 9A-9D  are merely illustrative. In general, any desired information such as wireless performance metric information, sensor information, device usage information, and impedance information may be used to determine which antennas are being loaded and detuned for selecting the pair of active antennas (e.g., for selecting which of the modes of  FIG. 8  to use). Fewer or more than four modes may be used if desired. Two, three, or more than four antennas  40  may be used. One, two, or more than two antennas may be active in each mode. By selectively activating different sets (e.g., pairs) of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  based on the orientation of device  10 , wireless circuitry  34  may obtain relatively high data throughput using multiple antennas regardless of how device  10  is being held by a user. 
     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: 20170927
Publication Date: 20181225
Grant Date: 20181225
Priority Date: 20170927
Inventors: RAJAGOPALAN, HARISH
AZAD, Umar
ROMANO, Pietro
Garrido Lopez, David
ZHANG, LU
GOMEZ ANGULO, RODNEY A.
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B1/44", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M1/0202", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3827", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/0413", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/0202", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/0202", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/44", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B1/3827", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/0413", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B1/3827", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/44", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 64692424