PATENT DOCUMENT

Publication Number: US-10476167-B2
Application Number: US-201715655660-A
Country: US
Kind Code: B2

Title: Adjustable multiple-input and multiple-output antenna structures

Abstract:
An electronic device may include antennas, a ground, and a housing. First and second gaps in the housing may define a segment that forms a resonating element for a first antenna. First, second, third, and fourth antenna feeds may be coupled between the segment and ground. Control circuitry may control adjustable components to place the device in first, second, third, or fourth modes. In the first and second modes, the first and fourth feeds convey signals at the same frequency using a multiple-input and multiple-output scheme while the second and third feeds are inactive. In the third mode, the second feed is active and the first, third, and fourth feeds are inactive. In the fourth mode, the third feed is active and the first, second, and fourth antenna feeds are inactive. Isolating return paths may be coupled between the segment and ground in the first and second modes.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 first and second gaps in the peripheral conductive structures that define a segment of the peripheral conductive structures; 
 an antenna ground; 
 a first antenna feed coupled between a first location on the segment and the antenna ground; 
 a second antenna feed coupled between a second location on the segment and the antenna ground; 
 a third antenna feed coupled between a third location on the segment and the antenna ground, wherein the second location is interposed between the first and third locations on the segment; 
 a plurality of adjustable components coupled to the segment; and 
 control circuitry, wherein the control circuitry is configured to adjust the plurality of adjustable components to place the electronic device in a selected one of a first operating mode in which the first and third antenna feeds are active and the second antenna feed is inactive and a second operating mode in which the second antenna feed is active and the first and third antenna feeds are inactive. 
 
     
     
       2. The electronic device defined in  claim 1 , further comprising:
 a fourth antenna feed coupled between a fourth location on the segment and the antenna ground, wherein the fourth location is interposed between the second and third locations. 
 
     
     
       3. The electronic device defined in  claim 2 , wherein the control circuitry is configured to adjust the plurality of adjustable components to place the electronic device in a third operating mode in which the fourth antenna feed is active and the first, second, and third antenna feeds are inactive, the fourth antenna feed being inactive in the first and second operating modes. 
     
     
       4. The electronic device defined in  claim 3 , wherein the second antenna feed comprises a first positive feed terminal and the fourth antenna feed comprises a second positive feed terminal, wherein the plurality of adjustable components comprises:
 a first adjustable component coupled between the first positive feed terminal and the second location on the segment; and 
 a second adjustable component coupled between the second positive feed terminal and the fourth location on the segment. 
 
     
     
       5. The electronic device defined in  claim 4 , wherein the first adjustable component forms a first short circuit path between the second location on the segment and the antenna ground and the second adjustable component forms a second short circuit path between the fourth location on the segment and the antenna ground in the first operating mode. 
     
     
       6. The electronic device defined in  claim 5 , wherein the plurality of adjustable components further comprises:
 a third adjustable component coupled between a fifth location on the segment and the antenna ground, the fifth location being interposed between the first and second locations on the segment; and 
 a fourth adjustable component coupled between a sixth location on the segment and the antenna ground, the sixth location being interposed between the third and fourth locations on the segment. 
 
     
     
       7. The electronic device defined in  claim 6 , wherein the third adjustable component forms a third short circuit path between the fifth location on the segment and the antenna ground and the fourth adjustable component forms an open circuit between the sixth location on the segment and the antenna ground in the second operating mode. 
     
     
       8. The electronic device defined in  claim 7 , wherein the fourth adjustable component forms a fourth short circuit path between the sixth location on the segment and the antenna ground and the third adjustable component forms an open circuit between the fifth location on the segment and the antenna ground in the third operating mode. 
     
     
       9. The electronic device defined in  claim 6 , wherein the control circuitry is configured to adjust the plurality of adjustable components to place the electronic device in a fourth operating mode in which the first and third antenna feeds are active and the second and fourth feeds are inactive, wherein the third adjustable component forms a short circuit between the fifth location on the segment and the antenna ground and the fourth adjustable component forms a short circuit between the sixth location on the segment and the antenna ground in the first operating mode, and the third and fourth adjustable components form open circuits between the segment and the antenna ground the fourth operating mode. 
     
     
       10. The electronic device defined in  claim 5 , further comprising:
 third and fourth gaps in the segment of the peripheral conductive structures, wherein the second adjustable component shorts the second positive feed terminal to opposing sides of the third gap and the first adjustable component shorts opposing sides of the fourth gap in the second operating mode, and the first adjustable component shorts the first positive feed terminal to opposing sides of the fourth gap and the second adjustable component shorts opposing sides of the third gap in the third operating mode. 
 
     
     
       11. The electronic device defined in  claim 5 , further comprising:
 radio-frequency transceiver circuitry in the housing and configured to concurrently convey radio-frequency signals over the first and third antenna feeds at a given frequency using a multiple-input and multiple-output (MIMO) antenna scheme in the first operating mode. 
 
     
     
       12. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 an antenna ground; 
 a first antenna that includes a first resonating element formed from a segment of the peripheral conductive structures extending between first and second dielectric-filled gaps in the peripheral conductive structures, a first antenna feed, and the antenna ground; 
 a second antenna that includes a second resonating element formed from a first portion of the first resonating element, a second antenna feed, and the antenna ground; 
 a third antenna that includes a third resonating element formed from a second portion of the first resonating element that is different from the first portion, a third antenna feed, and the antenna ground, wherein the electronic device is operable in a first mode of operation in which the first feed is enabled and the second and third feeds are disabled and in a second mode of operation in which the second and third feeds are enabled and the first feed is disabled; and 
 first and second adjustable components coupled between the segment and the antenna ground, wherein the first and second adjustable components are configured to form respective first and second short circuit paths between the segment and the antenna ground in the second mode of operation. 
 
     
     
       13. The electronic device defined in  claim 12 , wherein the first antenna feed comprises first and second feed terminals, the second feed terminal is coupled to the antenna ground, the first adjustable component is configured to short the first feed terminal to the segment in the first mode of operation, and the second adjustable component is configured to form an open circuit between the segment and the antenna ground in the first mode of operation. 
     
     
       14. The electronic device defined in  claim 13 , wherein the first antenna includes a fourth feed that is disabled in the first and second modes of operation and the electronic device is operable in a third mode of operation in which the fourth feed is enabled and the first, second, and third feeds are disabled. 
     
     
       15. The electronic device defined in  claim 14 , further comprising:
 sensor circuitry that gathers sensor data; and 
 control circuitry, wherein the control circuitry is configured to place the electronic device in a selected one of the first and third modes of operation based on the gathered sensor data. 
 
     
     
       16. The electronic device defined in  claim 12 , wherein the first antenna is configured to convey radio-frequency signals in a first frequency band, a second frequency band that is higher than the first frequency band, and a third frequency band that is higher than the second frequency band in the first operating mode, and the second and third antennas are configured to concurrently convey radio-frequency signals at the same set of frequencies within the second and third frequency bands in the second operating mode. 
     
     
       17. The electronic device defined in  claim 16 , wherein the first frequency band comprises frequencies from 600 MHz to 960 MHz, the second frequency band comprises frequencies from 1500 MHz to 2170 MHz, and the third frequency band comprises frequencies from 2300 MHz to 2700 MHz. 
     
     
       18. The electronic device defined in  claim 12 , further comprising:
 third and fourth dielectric-filled gaps in the segment of the peripheral conductive housing structures, wherein the first portion of the first resonating element extends from the first dielectric-filled gap to the third dielectric-filled gap, the second portion of the first resonating element extends from the second dielectric-filled gap to the fourth dielectric-filled gaps, the first adjustable component is configured to short opposing sides of the third dielectric-filled gap in the first mode of operation, and the second adjustable component is configured to short opposing sides of the fourth dielectric-filled gap in the first mode of operation. 
 
     
     
       19. Antenna structures, comprising:
 an antenna resonating element arm having opposing first and second ends, the antenna resonating element arm being formed from a segment of peripheral conductive housing structures for an electronic device; 
 an antenna ground; 
 a first antenna feed coupled between a first location on the antenna resonating element arm and the antenna ground; 
 a first adjustable component coupled between a second location on the antenna resonating element arm and the antenna ground, the first location being interposed between the second location and the first end of the antenna resonating element arm; 
 a second antenna feed coupled between a third location on the antenna resonating element arm and the antenna ground; 
 a third antenna feed coupled between a fourth location on the antenna resonating element arm and the antenna ground; and 
 a second adjustable component coupled between a fifth location on the antenna resonating element arm and the antenna ground, the third and fourth locations being interposed between the second and fifth locations on the antenna resonating element arm. 
 
     
     
       20. The electronic device defined in  claim 19 , further comprising:
 a fourth antenna feed coupled between a sixth location on the antenna resonating element arm and the antenna ground, the sixth location being interposed between the fifth location and the second end of the antenna resonating element arm; 
 a third adjustable component coupled between a seventh location on the antenna resonating element arm and the antenna ground, the seventh location being interposed between the first location and the first end of the antenna resonating element arm; and 
 a fourth adjustable component coupled between an eighth location on the antenna resonating element arm and the antenna ground, the eighth location being interposed between the sixth location and the second end of the antenna resonating element arm, wherein the first and fourth antenna feeds are configured to concurrently convey radio-frequency signals at the same frequency and a selected one of the second and third antenna feeds is configured to convey radio-frequency signals while the first and fourth antenna feeds are disabled.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless circuitry with antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, antennas are bulky. In other devices, antennas are compact, but are sensitive to the position of the antennas relative to external objects. If care is not taken, antennas may become detuned, may emit wireless signals with a power that is more or less than desired, or may otherwise not perform as expected. 
     In addition, it is often difficult to perform wireless communications with a satisfactory data rate (data throughput) using a single antenna in a wireless device, especially as software applications performed by wireless devices become increasingly data hungry. In order to increase the possible data rate for the wireless device, wireless devices can include multiple antennas that convey radio-frequency signals at the same frequency. However, it can be difficult to electromagnetically isolate multiple antennas operating at the same frequency, potentially leading to interference between the radio-frequency signals conveyed by each of the antennas and deterioration in the radio-frequency performance of the wireless device. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices such as electronic devices that include multiple antennas. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry and control circuitry. The wireless circuitry may include multiple antennas and transceiver circuitry. The antennas may include antenna structures at opposing first and second ends of the electronic device. The antenna structures at a given end of the device may include adjustable components that are adjusted by the control circuitry to place the antenna structures and the electronic device in one of a number of different operating modes or states. 
     The electronic device may include an antenna ground and a housing having peripheral conductive structures. First and second gaps in the peripheral conductive structures may define a segment that forms an antenna resonating element arm for a first antenna. First, second, third, and fourth antenna feeds may be coupled between different locations along the segment and the antenna ground. Adjustable components may be coupled to the segment. The control circuitry may control the adjustable components to place the electronic device in first or second operating modes. In the first and second operating modes, second and third antennas are formed. The second and third antennas have resonating element arms formed from respective portions of the resonating element arm of the first antenna. The first and fourth antenna feeds may be active (enabled) and the second and third antenna feeds may be inactive (disabled). The transceiver circuitry may concurrently convey radio-frequency signals at the same frequencies over the first and fourth antenna feeds (e.g., over the second and third antennas) using a multiple-input and multiple-output (MIMO) scheme. In the first operating mode, the second and third antennas may cover lower frequencies than in the second operating mode. 
     The control circuitry may control the adjustable components to place the electronic device in a selected one of third or fourth operating modes. In the third operating mode, the second antenna feed is active and the first, third, and fourth antenna feeds are inactive. In the fourth operating mode, the third antenna feed is active and the first, second, and fourth antenna feeds are inactive. The first antenna may convey radio-frequency signals over the active one of the second and third feeds at lower frequencies than are covered by the second and third antennas in the first and second operating modes. The control circuitry may place the device in a selected one of the third and fourth operating modes based on sensor data to compensate for any loading of the first antenna by the hand of a user of the electronic device. 
     In the first and second operating modes, at least first and second short circuit (return) paths may be coupled between the segment of the peripheral conductive structures and the antenna ground. The first and second short circuit paths may be interposed between the first and fourth antenna feeds and may serve to isolate the second and third antennas, despite the second and third antennas operating at the same frequencies (e.g., for performing MIMO communications) and despite the second and third antennas including resonating element arms formed from portions of the same peripheral conductive housing structures. If desired, one or more dielectric-filled gaps may be provided in the segment of the peripheral conductive structures to further isolate the second and third antennas in the first and second operating modes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a diagram showing how radio-frequency transceiver circuitry may be coupled to one or more antennas within an electronic device in accordance with an embodiment. 
         FIG. 4  is a diagram of illustrative wireless communications circuitry in accordance with an embodiment. 
         FIG. 5  is a schematic diagram of an illustrative inverted-F antenna in accordance with an embodiment. 
         FIG. 6  is a schematic diagram of an illustrative slot antenna in accordance with an embodiment. 
         FIG. 7  is a diagram of illustrative antenna structures that are switchable between multiple operating modes in accordance with an embodiment. 
         FIG. 8  is a diagram of an illustrative switch that may be used in antenna structures in accordance with an embodiment. 
         FIG. 9  is a diagram of an illustrative adjustable single-element inductor that may be used in antenna structures in accordance with an embodiment. 
         FIG. 10  is a diagram of an illustrative multi-element inductor that may be used in antenna structures in accordance with an embodiment. 
         FIG. 11  is a diagram of illustrative switchable inductor circuitry that may be coupled to an antenna feed in accordance with an embodiment. 
         FIG. 12  is a diagram of illustrative antenna structures having dielectric gaps for enhancing electromagnetic isolation between multiple antennas in accordance with an embodiment. 
         FIG. 13  is a flow chart of illustrative steps that may be involved in operating an electronic device having antenna structures of the type shown in  FIGS. 7-12  in accordance with an embodiment. 
         FIG. 14  is a state diagram showing illustrative wireless operating modes for an electronic device in accordance with embodiment. 
         FIG. 15  is a graph in which antenna performance (standing-wave ratio) has been plotted as a function of operating frequency for antenna structures of the type shown in  FIGS. 7-12  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support wireless communications in multiple wireless communications bands. 
     The wireless communications circuitry may include one more antennas. The antennas of the wireless communications circuitry can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, dipole antennas, monopole antennas, helical antennas, patch antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. 
     The conductive electronic device structures may include conductive housing structures. The housing structures may include peripheral structures such as peripheral conductive structures that run around the periphery of an electronic device. The peripheral conductive structures may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. 
     Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for electronic device  10 . Antennas may also be formed using an antenna ground plane formed from conductive housing structures such as metal housing midplate structures and other internal device structures. Rear housing wall structures may be used in forming antenna structures such as an antenna ground. 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a portable electronic device such as a laptop computer, a tablet computer, a cellular telephone, a media player, a remote control device, a wearable device such as a wristwatch device, pendant device, headphone or earpiece device, virtual or augmented reality headset device, device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, gaming controller, computer mouse, keyboard, mousepad, a navigation device, or trackpad or touchpad device, or electronic device  10  may be a larger device such as a television, a computer monitor containing an embedded computer, a computer display that does not contain an embedded computer, a gaming device, an embedded system such as a system in which electronic equipment is mounted in a kiosk, building, vehicle, or automobile, a wireless access point or base station, a desktop computer, equipment that implements the functionality of two or more of these devices, or other electronic equipment. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may be mounted on the front face of device  10 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. The rear face of housing  12  (i.e., the face of device  10  opposing the front face of device  10 ) may have a planar housing wall. The rear housing wall may be have slots that pass entirely through the rear housing wall and that therefore separate housing wall portions (and/or sidewall portions) of housing  12  from each other. Housing  12  (e.g., the rear housing wall, sidewalls, etc.) may also have shallow grooves that do not pass entirely through housing  12 . The slots and grooves may be filled with plastic or other dielectric. If desired, portions of housing  12  that have been separated from each other (e.g., by a through slot) may be joined by internal conductive structures (e.g., sheet metal or other metal members that bridge the slot). 
     Display  14  may include pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable pixel structures. A display cover layer such as a layer of clear glass or plastic may cover the surface of display  14  or the outermost layer of display  14  may be formed from a color filter layer, thin-film transistor layer, or other display layer. Buttons such as button  24  may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port  26 . Speaker port  26  may allow audio signals (sound) to be heard by a user of device  10  (e.g., while the user holds device  10  and speaker port  26  to their ear). Speaker port  26  may therefore sometimes be referred to herein as ear speaker port  26  or ear speaker  26 . 
     Housing  12  may include peripheral housing structures such as structures  16 . Structures  16  may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, structures  16  may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (as an example). Peripheral structures  16  or part of peripheral structures  16  may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ). Peripheral structures  16  may also, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.). 
     Peripheral housing structures  16  may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, or a peripheral conductive housing member (as examples). Peripheral housing structures  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral housing structures  16 . If desired, holes such as holes  17  may be provided in peripheral structures  16  or in a rear surface of housing  12 . Speakers within device  10  may transmit sound to the exterior of device  10  through holes  17  and/or through ear speaker  26 . If desired, microphones may be placed adjacent to holes  17  or any other desired locations within device  10  on to generate audio signals from sound received by device  10 . 
     It is not necessary for peripheral housing structures  16  to have a uniform cross-section. For example, the top portion of peripheral housing structures  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral housing structures  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral housing structures  16  may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral housing structures  16  serve as a bezel for display  14 ), peripheral housing structures  16  may run around the lip of housing  12  (i.e., peripheral housing structures  16  may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, housing  12  may have a conductive rear surface. For example, housing  12  may be formed from a metal such as stainless steel or aluminum. The rear surface of housing  12  may lie in a plane that is parallel to display  14 . In configurations for device  10  in which the rear surface of housing  12  is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  16  as integral portions of the housing structures forming the rear surface of housing  12 . For example, a rear housing wall of device  10  may be formed from a planar metal structure and portions of peripheral housing structures  16  on the sides of housing  12  may be formed as flat or curved vertically extending integral metal portions of the planar metal structure. Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . The planar rear wall of housing  12  may have one or more, two or more, or three or more portions. 
     Housing  12  may include internal conductive structures such as metal frame members and a planar conductive housing member (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more parts that is welded or otherwise connected between opposing sides of member  16 ). Device  10  may also include conductive structures such as printed circuit boards, components mounted on printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground plane in device  10 , may be located in the center of housing  12 . 
     In regions  22  and  20 , openings may be formed within the conductive structures of device  10  (e.g., between peripheral conductive housing structures  16  and opposing conductive ground structures such as conductive housing midplate or rear housing wall structures, a printed circuit board, and conductive electrical components in display  14  and device  10 ). These openings, which may sometimes be referred to as gaps, may be filled with air, plastic, and other dielectrics and may be used in forming slot antenna resonating elements for one or more antennas in device  10 . 
     Conductive housing structures and other conductive structures in device  10  such as a midplate, traces on a printed circuit board, display  14 , and conductive electronic components may serve as a ground plane for the antennas in device  10 . The openings in regions  20  and  22  may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element from the ground plane, may contribute to the performance of a parasitic antenna resonating element, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . 
     In general, device  10  may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). In the example of  FIG. 1 , device  10  includes a first antenna  40 L and a second antenna  40 U formed on opposing sides of device  10 . For example, antenna  40 L may be formed within region  20  at the lower end of device  10  (e.g., the end of device  10  adjacent to microphone holes  17 ) and may therefore sometimes be referred to herein as lower antenna  40 L. Similarly, antenna  40 U may be formed within region  22  at the upper end of device  10  (e.g., the end of device  10  adjacent to ear speaker  26 ) and may therefore sometimes be referred to herein as upper antenna  40 U. Antennas  40 L and  40 U may, if desired, be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme. In the MIMO antenna scheme, antennas  40 L and  40 U concurrently (e.g., simultaneously) convey radio-frequency signals at one or more of the same frequencies. 
     The arrangement of  FIG. 1  is merely illustrative. In general, the antennas in device  10  may be located at opposing first and second ends of an elongated device housing (e.g., at ends  20  and  22  of device  10  of  FIG. 1 ), along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of these locations. Additional antennas may be formed in regions  22  and/or  20 . Antennas in regions  22  may have the same architecture or architecture that is mirrored with respect to antennas in regions  20  or antennas in regions  22  may have different architecture than antennas in region  20 . If desired, structures that are used in forming other antennas in region  22  may also be used to form antenna  40 U. Similarly, structures that are used in forming other antennas in region  20  may also be used to form antenna  40 L. 
     Portions of peripheral housing structures  16  may be provided with peripheral gap structures. For example, peripheral conductive housing structures  16  may be provided with one or more gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral housing structures  16  may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide peripheral housing structures  16  into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral housing structures  16  (e.g., in an arrangement with two of gaps  18 ), three peripheral conductive segments (e.g., in an arrangement with three of gaps  18 ), four peripheral conductive segments (e.g., in an arrangement with four gaps  18 , etc.). 
     The segments of peripheral conductive housing structures  16  that are formed in this way may form parts of antennas in device  10 . For example, the segment of peripheral conductive housing structures  16  that is located between the two gaps  18  in region  20  may form some or all of an antenna resonating element for lower antenna  40 L or for other antennas in region  20  (e.g., one or more resonating element arms of an inverted-F antenna resonating element in scenarios where lower antenna  40 L is an inverted-F antenna, a portion of a loop antenna resonating element in scenarios where lower antenna  40 L is a loop antenna, a conductive portion that defines an edge of a slot antenna resonating element in scenarios where lower antenna  40 L is a slot antenna, combinations of these, or any other desired antenna resonating element structures). Similarly, the segment of peripheral conductive housing structures  16  that is located between the two gaps  18  in region  22  may form some or all of an antenna resonating element for upper antenna  40 U or other antennas in region  22 . This example is merely illustrative. If desired, antennas  40 L and  40 U may not include any portion of peripheral conductive housing structures  16  or segments of structures  16  may form part of an antenna ground plane for antennas  40 L,  40 U, and/or other antennas in device  10 . 
     Antennas in device  10  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc. 
     A schematic diagram showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols (e.g., Long-Term Evolution (LTE) protocols, LTE Advanced protocols, Global System for Mobile Communications (GSM) protocols, Universal Mobile Telecommunications System (UMTS) protocols, or other mobile telephone protocols), multiple-input and multiple-output (MIMO) protocols, antenna diversity protocols, combinations of these, 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, sensors such as light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, antenna impedance sensors, 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 ), or other sensors, 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  38  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  45 ,  46 , and  47 . Transceiver circuitry  46  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications or other wireless local area network (WLAN) bands and may handle the 2.4 GHz Bluetooth® communications band or other wireless personal area network (WPAN) bands. Circuitry  34  may use cellular telephone transceiver circuitry  47  for handling wireless communications in frequency ranges such as a low communications band from 600 to 960 MHz, a low midband from 1400-1520 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 600 MHz and 4000 MHz or other suitable frequencies (as examples). Circuitry  47  may handle voice data and non-voice data using one or more cellular telephone protocols (e.g., Long-Term Evolution (LTE) protocols, LTE Advanced protocols, Global System for Mobile Communications (GSM) protocols, Universal Mobile Telecommunications System (UMTS) protocols, other mobile telephone protocols, etc.). 
     Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment such as GPS receiver circuitry  45  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antenna structures, dipole 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. 
     Antenna diversity schemes may be implemented in which multiple redundant antennas are used in handling communications for a particular band or bands. In an antenna diversity scheme, storage and processing circuitry  28  may select which antenna to use in real time based on signal strength measurements or other data. In another suitable arrangement, multiple antennas  40  may perform communications using multiple-input-multiple-output (MIMO) schemes. In MIMO schemes, multiple antennas  40  may be used to transmit and/or receive multiple data streams at one or more of the same frequencies, thereby enhancing data throughput. 
     Illustrative locations in which multiple antennas  40  may be formed in device  10  are shown in  FIG. 3 . As shown in  FIG. 3 , multiple antennas  40  may be mounted within housing  12  and may, if desired, be formed using parts of housing  12  (e.g., parts of peripheral conductive housing structures  16  of  FIG. 1 ). Multiple antennas  40  may be coupled to transceiver circuitry  38  by paths such as paths  50 . Paths  50  may include transmission line structures such as coaxial cables, microstrip transmission lines, stripline transmission lines, etc. 
     Transceiver circuitry  38  may include one or more dedicated transmitters  48 , one or more dedicated receivers  49 , or one or more transceiver circuits that perform both transmission and reception. Transmitters  48 , receivers  49 , and transceiver circuits that perform both transmission and reception in circuitry  38  may handle satellite navigation signals (e.g., as a part of circuits  45  of  FIG. 2 ), wireless local area network signals (e.g., as a part of circuits  46  of  FIG. 2 ), voice and/or non-voice cellular telephone signals (e.g., as a part of circuits  47  of  FIG. 2 ), or other signals (e.g., circuits  47 ,  46 , and  45  of  FIG. 2  may include one or more dedicated transmitters  48 , dedicated receivers  49 , or transceivers that perform both transmission and reception). Each dedicated receiver  49 , transmitter  48 , and transceiver in circuitry  38  may be formed on the same integrated circuit, module, printed circuit, package, or substrate within device  10  or two or more of receivers  49 , transmitters  48 , and transceivers in circuitry  38  may be formed on separate integrated circuits, modules, packages, printed circuits, or substrates within device  10 . If desired, amplifiers, filter circuitry, radio-frequency coupler circuitry, switching circuitry, analog-to-digital converter circuitry, digital-to-analog converter circuitry, mixer circuitry, or other circuitry may be formed as a part of transceiver circuitry  38  or interposed on paths  50 . 
     In a device such as a cellular telephone that has an elongated rectangular outline, it may be desirable to place antennas  40  at one or both ends of the device. As shown in  FIG. 3 , for example, some of antennas  40  may be placed in upper end region  22  of housing  12  and some of antennas  40  may be placed in lower end region  20  of housing  12 . 
     Antenna structures  40  may be formed within some or all of regions such as regions  22  and  20 . For example, an antenna such as antenna  40 U- 1  may be located within region  42 - 1  and/or an antenna such as antenna  40 U- 2  may be located within region  42 - 3 . Each antenna  40 U- 1  and  40 U- 2  may be coupled to transceiver circuitry  38  by a corresponding transmission line  50  (e.g., antenna  40 U- 1  may be coupled to a first port of transceiver circuitry  38  by transmission line  50 - 1  whereas antenna  40 U- 2  is coupled to a second port of transceiver circuitry  38  by transmission line  50 - 2 ). 
     If desired, switching circuitry may be coupled between antennas  40 U- 1  and  40 U- 2 . Control circuitry  28  may control the switching circuitry to configure antennas  40 U- 1  and  40 U- 2  to form a single larger antenna  40 U that occupies some or all of region  42 - 2 . Antenna  40 U may include antenna structures from both antennas  40 U- 1  and  40 U- 2 . Antenna  40 U may be fed using a selected one of transmission lines  50 - 1  and  50 - 2  or using other transmission lines (not shown) coupled to transceiver circuitry  38 . Control circuitry  28  may control the switching circuitry to configure components in region  22  to form to separate antennas  40 U- 1  and  40 U- 2  or to form a single antenna  40 U based on device operating conditions, wireless communications requirements, sensor data, or other information (e.g., to optimize wireless performance for device  10 ). 
     Similarly, an antenna such as antenna  40 L- 1  may be located within region  44 - 1  and/or an antenna such as antenna  40 L- 2  may be located within region  44 - 3 . Each antenna  40 L- 1  and  40 L- 2  may be coupled to transceiver circuitry  38  by a corresponding transmission line  50  (e.g., antenna  40 L- 1  may be coupled to a first port of transceiver circuitry  38  by transmission line  50 - 3  whereas antenna  40 L- 4  is coupled to a second port of transceiver circuitry  38  by transmission line  50 - 4 ). 
     If desired, switching circuitry may be coupled between antennas  40 L- 1  and  40 L- 2 . Control circuitry  28  may control the switching circuitry to configure antennas  40 L- 1  and  40 L- 2  to form a single larger antenna  40 L that occupies some or all of region  44 - 2 . Antenna  40 L may include antenna structures from both antennas  40 L- 1  and  40 L- 2 . Antenna  40 L may be fed using a selected one of transmission lines  50 - 3  and  50 - 4  or using other transmission lines (not shown) coupled to transceiver circuitry  38 . Control circuitry  28  may control the switching circuitry to configure components in region  20  to form to separate antennas  40 L- 1  and  40 L- 2  or to form a single antenna  40 L based on device operating conditions, wireless communications requirements, sensor data, or other information (e.g., to optimize wireless performance for device  10 ). 
     Antennas  40 U and  40 L may occupy a larger space (e.g., a larger area or volume within device  10 ) than antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , or  40 L- 2 . This may allow antennas  40 U and  40 L to support communications at longer wavelengths (i.e., lower frequencies) than antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , or  40 L- 2  if desired. In one suitable arrangement, control circuitry  28  may control switching circuitry in regions  22  and  20  to form antennas  40 U and  40 L when it is desired to convey radio-frequency signals at frequencies that are lower than can otherwise be handled by antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , or  40 L- 2 . 
     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  such as antennas  40 U- 1 ,  40 U- 2 ,  40 U,  40 L,  40 L- 1 , and/or  40 L- 2  may be operated using multiple-input and multiple-output (MIMO) schemes. 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 . 
     However, if care is not taken, radio-frequency signals conveyed in the same frequency band by multiple antennas  40  may interfere with each other, serving to deteriorate the overall wireless performance of circuitry  34 . Ensuring that antennas operating at the same frequency are electromagnetically isolated from each other can be particularly challenging for adjacent antennas  40  (e.g., antennas  40 U- 1  and  40 U- 2 , antennas  40 L- 1  and  40 L- 2 , etc.) and for antennas  40  that have common (shared) structures (e.g., that have resonating elements formed from adjacent or shared conductive portions of housing  12 ). 
     In order to perform wireless communications under a MIMO scheme, antennas  40  need to convey data at the same frequencies. If desired, wireless circuitry  34  may perform so-called two-stream (2×) MIMO operations (sometimes referred to herein as 2×MIMO communications or communications using a 2×MIMO scheme) in which two antennas  40  are used to convey two independent streams of radio-frequency signals at the same frequency. Wireless circuitry  34  may perform so-called four-stream (4×) MIMO operations (sometimes referred to herein as 4×MIMO communications or communications using a 4×MIMO scheme) in which four antennas  40  are used to convey four independent streams of radio-frequency signals at the same frequency. Performing 4×MIMO operations may support higher overall data throughput than 2×MIMO operations because 4×MIMO operations involve four independent wireless data streams whereas 2×MIMO operations involve only two independent wireless data streams. If desired, pairs of antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , and  40 L- 2  may perform 2×MIMO operations in one or more frequency bands and/or all of antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , and  40 L- 2  may perform 4×MIMO operations in one or more frequency bands (e.g., depending on which bands are handled by which antennas). If desired, antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , and  40 L- 2  may perform 2×MIMO operations in some bands concurrently with performing 4×MIMO operations in other bands, for example. When antennas  40 U- 1  and  40 U- 2  are configured to form upper antenna  40 U and antennas  40 L- 1  and  40 L- 2  are configured to form lower antenna  40 L, wireless circuitry  34  may perform 2×MIMO operations using antennas  40 U and  40 L at one or more frequencies, for example. Antennas  40 U and  40 L need not perform communications using a MIMO scheme if desired. 
       FIG. 4  is a diagram showing how transceiver circuitry  38  may be coupled to each antenna  40  using a corresponding transmission path  50 . As shown in  FIG. 4 , transceiver circuitry  38  in wireless circuitry  34  may be coupled to antenna structures  40  (e.g., a given one of antennas  40 U- 1 ,  40 U- 2 ,  40 U,  40 L- 1 ,  40 L- 2 , or  40 L as shown in  FIG. 3 ) using paths such as path  50  (e.g., a corresponding one of paths  50 - 1 ,  50 - 2 ,  50 - 3 ,  50 - 4 , or other transmission line paths  50 ). Wireless circuitry  34  may be coupled to control circuitry  28 . Control circuitry  28  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures such as antenna(s)  40  with the ability to cover communications frequencies of interest, antenna(s)  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). 
     If desired, antenna(s)  40  may be provided with adjustable circuits such as tunable components  60 . Tunable components  60  may place antenna structures  40  in one of a number of possible operating modes and/or may tune antenna structures  40  over communications bands of interest. Tunable components  60  may be part of a tunable filter or tunable impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and antenna ground, etc. Tunable components  60  may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of device  10 , control circuitry  28  may issue control signals on one or more paths such as path  62  that adjust inductance values, capacitance values, or other parameters associated with tunable components  60 , thereby tuning antenna structures  40  to cover desired communications bands. If desired, components  60  may include fixed (non-adjustable) tuning components such as capacitors, resistors, and/or inductors. 
     Path  50  may include one or more transmission lines. As an example, signal path  50  of  FIG. 2  may be a transmission line having a positive signal conductor such as line  52  and a ground signal conductor such as line  54 . Lines  52  and  54  may form parts of a coaxial cable, a stripline transmission line, or a microstrip transmission line (as examples). A matching network formed from components such as fixed or tunable inductors, resistors, and capacitors may be used in matching the impedance of antenna(s)  40  to the impedance of transmission line  50 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna(s)  40  and may be tunable and/or fixed components (e.g., components  60 ). 
     Transmission line  50  may be coupled to antenna feed structures such as antenna feed F 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 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  52  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  54  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. 4  is merely illustrative. 
     Antenna structures  40  may include resonating element structures, antenna ground plane structures, an antenna feed such as feed F, and other components (e.g., tunable components  60 ). Antenna structures  40  may be configured to form any suitable types of antenna. With one suitable arrangement, which is sometimes described herein as an example, antenna structures  40  are used to implement a hybrid inverted-F-slot antenna that includes both inverted-F and slot antenna resonating elements. 
     If desired, tunable components  60  may include switching circuitry that is controlled by control circuitry  28  to configure antenna structures in region  22  to form two separate antennas  40 U- 1  and  40 U- 2  or a single antenna  40 U (or to configure antenna structures in region  20  to form two separate antennas  40 L- 1  and  40 L- 2  or a single antenna  40 L). Switching circuits in tunable components  60  may, if desired, couple antenna structures  40  to one or more selected transmission line paths  50 . 
     Antennas  40  in device  10  may be formed using any desired antenna type. For example, an antenna  40  may include an antenna with a resonating element that is formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antenna structures, dipole antenna structures, hybrids of these designs, etc.  FIG. 5  is a diagram of illustrative inverted-F antenna structures that may be used in implementing an antenna  40  for device  10 . 
     As shown in  FIG. 5 , antenna  40  may include inverted-F antenna resonating element  106  and antenna ground (ground plane)  104 . Antenna resonating element  106  may have a main resonating element arm such as arm  108 . The length of arm  108  and/or portions of arm  108  may be selected so that antenna  40  resonates at desired operating frequencies. For example, the length of arm  108  may be a quarter of a wavelength at a desired operating frequency for antenna  40 . Antenna  40  may also exhibit resonances at harmonic frequencies. 
     Main resonating element arm  108  may be coupled to ground  104  by return path  110 . An inductor or other component may be interposed in path  110  and/or tunable components  60  ( FIG. 4 ) may be interposed in path  110 . If desired, tunable components  60  may be coupled in parallel with path  110  between arm  108  and ground  104 . Additional return paths  110  may be coupled between arm  108  and ground  104  if desired. 
     Antenna  40  may be fed using one or more antenna feeds. For example, antenna  40  may be fed using antenna feed F. Antenna feed F may include positive antenna feed terminal  98  and ground antenna feed terminal  100  and may run in parallel to return path  110  between arm  108  and ground  104 . If desired, inverted-F antennas such as illustrative antenna  40  of  FIG. 5  may have more than one resonating arm branch (e.g., to create multiple frequency resonances to support operations in multiple communications bands) or may have other antenna structures (e.g., parasitic antenna resonating elements, tunable components to support antenna tuning, etc.). For example, arm  108  may have left and right branches that extend outwardly from feed F and return path  110 . Multiple feeds may be used to feed antennas such as antenna  40 . 
     Antenna  40  may be a hybrid antenna that includes one or more slot antenna resonating elements. As shown in  FIG. 6 , for example, antenna  40  may be based on a slot antenna configuration having an opening such as slot  114  that is formed within conductive structures such as antenna ground  104 . Slot  114  (sometimes referred to herein as opening  114 ) may be filled with air, plastic, and/or other dielectric. The shape of slot  114  may be straight or may have one or more bends (i.e., slot  114  may have an elongated shape following a meandering path). Feed terminals  98  and  100  may, for example, be located on opposing sides of slot  114  (e.g., on opposing long sides). Slot-based antenna resonating elements such as slot antenna resonating element  114  of  FIG. 6  may give rise to an antenna resonance at frequencies in which the wavelength of the antenna signals is equal to the perimeter of the slot. In narrow slots, the resonant frequency of a slot antenna resonating element is associated with signal frequencies at which the slot length is equal to a half of a wavelength. 
     Slot antenna frequency response can be tuned using one or more tuning components (e.g., components  60  of  FIG. 4 ). These components may have terminals that are coupled to opposing sides of the slot (i.e., the tunable components may bridge the slot). If desired, tunable components may have terminals that are coupled to respective locations along the length of one of the sides of slot  114 . Combinations of these arrangements may also be used. If desired, antenna  40  may be a hybrid slot-inverted-F antenna that includes resonating elements of the type shown in both  FIG. 5  and  FIG. 6  (e.g., having resonances given by both a resonating element arm such as arm  108  of  FIG. 5  and a slot such as slot  114  of  FIG. 6 ). 
     An illustrative configuration for an antenna with slot and inverted-F antenna structures such as antenna  40 L of  FIG. 3  is shown in  FIG. 7 . The presence or absence of external objects such as a user&#39;s hand or other body part in the vicinity of antenna  40 L 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 the user&#39;s right hand and may be affected in another way when a user is holding device  10  in the user&#39;s left hand. 
     As shown  FIG. 7 , adjustable components  60  ( FIG. 4 ) in antenna  40 L may include adjustable components such as components T 0 , T 1 , T 2 , T 3 , T 4 , T 5 , T 6 , and T 7 . 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  30  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 components T 0 , T 1 , T 2 , T 3 , T 4 , T 5 , T 6 , and T 7  to compensate for the loading. 
     In order to further help compensate for antenna loading due to the presence of external objects such as the user&#39;s hand at different locations relative to device  10 , antenna  40 L may include multiple antenna feeds (e.g., antenna feeds such as antenna feed F of  FIG. 4 ). Control circuitry  28  may selectively activate one of the multiple antenna feeds at a given time. For example, control circuitry  28  may selectively activate the antenna feed that is located farthest away from an external object that is loading the antenna to help minimize the impact of the presence of the external object on the performance of antenna  40 . 
     As shown in  FIG. 7 , antenna  40 L (e.g., a hybrid slot-inverted-F antenna) may include multiple feeds F such as a first feed F 1 , a second feed F 2 , a third feed F 4 , and a fourth feed F 5  coupled between resonating element arm  108  and ground  104  across slot  114 . Feeds F 1 , F 2 , F 3 , and F 4  may be coupled to one or more transceivers in transceiver circuitry  38  via corresponding transmission lines  50  ( FIGS. 3 and 4 ). 
     Resonating element arm  108  of antenna  40 L may be formed from a portion of housing  12  such as a segment of peripheral conductive structures  16  that extends between gaps  18 - 1  and  18 - 2  (e.g., gaps  18  in peripheral conductive structures  13  as shown in  FIG. 1 ). Slot  114  may be formed from an elongated gap between peripheral conductive structures  16  and ground  104  (e.g., a slot formed in housing  12  using machining tools or other equipment). For example, a first end of the segment of peripheral structures  16  that forms resonating element arm  108  may define an edge of gap  18 - 1  whereas an opposing second end of the segment of peripheral structures  16  defines an edge of gap  18 - 2 . The slot may be filled with dielectrics such as air and/or plastic. For example, plastic may be inserted into portions of slot  114  and this plastic may be flush with the outside of housing  12 . Portions of slot  114  may contribute slot antenna resonances to antenna  40 L. 
     Antenna feeds F 1 , F 2 , F 3 , and F 4  may include respective positive antenna feed terminals  98  and ground antenna feed terminals  100 . For example, first antenna feed F 1  may include a positive antenna feed terminal  98 - 1  and a corresponding ground antenna feed terminal  100 - 1  that are coupled to opposing sides of slot  114 . Positive antenna feed terminal  98 - 1  may be coupled to peripheral conductive structures  16  via feed leg  143  whereas ground antenna feed terminal  100 - 1  is coupled to ground plane  104 . 
     Similarly, second antenna feed F 2  may include a positive antenna feed terminal  98 - 2  and a corresponding ground antenna feed terminal  100 - 2  that are coupled to opposing sides of slot  114 . Positive antenna feed terminal  98 - 2  may be coupled to peripheral conductive structures  16  via feed leg  150  whereas ground antenna feed terminal  100 - 2  is coupled to ground plane  104 . Third antenna feed F 3  may include a positive antenna feed terminal  98 - 3  and a corresponding ground antenna feed terminal  100 - 3  that are coupled to opposing sides of slot  114 . Positive antenna feed terminal  98 - 3  may be coupled to peripheral conductive structures  16  via feed leg  148  whereas ground antenna feed terminal  100 - 3  is coupled to ground plane  104 . Fourth antenna feed F 4  may include a positive antenna feed terminal  98 - 4  and a corresponding ground antenna feed terminal  100 - 4  that are coupled to opposing sides of slot  114 . Positive antenna feed terminal  98 - 4  may be coupled to peripheral conductive structures  16  via feed leg  125  whereas ground antenna feed terminal  100 - 4  is coupled to ground plane  104 . 
     Feed F 3  may be interposed between feeds F 4  and F 2  and feed F 2  may be interposed between feeds F 3  and F 1 . If desired, feeds F 1 , F 2 , F 3 , and F 4  may be symmetrically distributed about central longitudinal axis  133  of device  10  (e.g., a central axis  133  that bisects device  10  and runs parallel to the longest dimension of device  10 ). For example, feeds F 3  and F 2  may be located at approximately the same distance from opposing sides of axis  133  and feeds F 1  and F 4  may be located at approximately the same distance from opposing sides of axis  133  (e.g., feeds F 1  and F 2  may be respectively located at the same distances from gap  18 - 2  as feeds F 4  and F 3  are from gap  18 - 1 ). This example is merely illustrative. In general, antenna feeds F 1  and F 2  may be located at any desired distances with respect to a first side of axis  133  and antenna feeds F 3  and F 4  may be located at any desired distances with respect to a second side of axis  133  (e.g., where feed F 2  is closer to axis  133  than feed F 1  and feed F 3  is closer to axis  133  than feed F 4 ). 
     Feed legs  143 ,  150 ,  148 , and  125  may sometimes be referred to herein as feed arms, feed paths, feed conductors, or feed elements. Feed legs  143 ,  150 ,  148 , and  125  may include any desired conductive structures such as conductive wire, metal traces on a rigid or flexible printed circuit board, sheet metal, metal portions of electronic device components, conductive radio-frequency connectors, conductive spring structures, metal screws or other fasteners, weld structures, solder structures, conductive adhesive structures, combinations of these structures, etc. Feed leg  143  may be coupled to peripheral conductive structures  16  at point  142  whereas feed leg  150  is coupled to structures  16  at point  136 , feed leg  148  is coupled to structures  16  at point  132 , and feed leg  125  is coupled to structures  136  at point  124 . 
     Adjustable components  60  of  FIG. 4  may include adjustable components T 0 , T 1 , T 2 , T 3 , T 4 , T 5 , T 6 , and T 7  of  FIG. 7 . Adjustable component T 1  may be interposed on feed leg  143  between feed terminal  98 - 1  and peripheral structures  16 . Adjustable component T 3  may be interposed on feed leg  150  between feed terminal  98 - 2  and peripheral structures  16 . Adjustable component T 4  may be interposed on feed leg  148  between feed terminal  98 - 3  and peripheral structures  16 . Adjustable component T 4  may be interposed on feed leg  125  between feed terminal  98 - 4  and peripheral structures  16 . 
     Control circuitry  28  may adjust components T 1 , T 3 , T 4 , and T 6  to selectively activate one or more of feeds F 1 , F 2 , F 3 , and F 4  at a given time and/or to adjust the performance of antenna  40 . Component T 1  may, for example, include a switch coupled between terminal  98 - 1  and point  142 . Similarly, component T 6  may include a switch coupled between terminal  98 - 4  and point  124 . Control circuitry  28  may turn the switch in component T 1  to couple feed terminal  98 - 1  to point  142 , thereby activating feed F 1 , and may turn off the switch in component T 2  to decouple feed terminal  98 - 1  from point  142 , thereby deactivating feed F 1 . Similarly, control circuitry  28  may turn the switch in component T 6  to couple feed terminal  98 - 4  to point  124 , thereby activating feed F 4 , and may turn off the switch in component T 6  to decouple feed terminal  98 - 4  from point  124 , thereby deactivating feed F 4 . 
     Component T 3  may include switching circuitry having a first switch port (terminal) P 4  coupled to point  136 , a second switch port P 5  coupled to point  134  on ground  104 , and a third switch port P 6  coupled to feed terminal  98 - 2 . The switching circuitry in component T 3  may have a first state at which port P 6  is coupled to port P 4 , a second state at which port P 4  is coupled to port P 5 , and a third state at which an open circuit is formed between each of ports P 4 , P 5 , and P 6 . When the switching circuitry in component T 3  is in the first state, feed terminal  98 - 2  may be coupled to point  136  and feed F 2  may be active. When the switching circuitry in component T 3  is in the second state, a return (short circuit) path is formed between point  136  on structures  16  and point  134  on antenna ground  104 , feed terminal  98 - 2  is decoupled peripheral structures  16 , and feed F 2  is inactive. When the switching circuitry in component T 3  is in the third state, an open circuit is formed between peripheral structures  16  and ground  104  at the location of feed F 2  and feed F 2  is inactive. 
     Component T 4  may include switching circuitry having a first switch port (terminal) P 1  coupled to point  132 , a second switch port P 2  coupled to point  130  on ground  104 , and a third switch port P 3  coupled to feed terminal  98 - 3 . The switching circuitry in component T 4  may have a first state at which port P 1  is coupled to port P 3 , a second state at which port P 1  is coupled to port P 2 , and a third state at which an open circuit is formed between each of ports P 1 , P 2 , and P 3 . When the switching circuitry in component T 4  is in the first state, feed terminal  98 - 3  may be coupled to point  132  and feed F 3  may be active. When the switching circuitry in component T 4  is in the second state, a return (short circuit) path is formed between point  132  on structures  16  and point  130  on antenna ground  104 , feed terminal  98 - 3  is decoupled from peripheral structures  16 , and feed F 3  is inactive. When the switching circuit in component T 4  is in the third state, an open circuit is formed between peripheral structures  16  and ground  104  at the location of feed F 3  and feed F 3  is inactive. By adjusting components T 6 , T 4 , T 3 , and T 1 , control circuitry  28  may selectively activate one or more of feeds F 4 , F 3 , F 2 , and F 1  at a given time. 
     Adjustable components T 0 , T 2 , T 5 , and T 7  may be coupled between ground  104  and peripheral structures  16  across slot  114 . For example, a first terminal  146  of adjustable component T 0  may be coupled to ground  104  whereas a second terminal  144  of adjustable component T 0  is coupled to peripheral structures  16 . A first terminal  140  of component T 2  may be coupled to ground  104  whereas a second terminal  138  of component T 2  is coupled to peripheral structures  16 . A first terminal  126  of component T 5  may be coupled to ground  104  whereas a second terminal  128  of component T 5  is coupled to peripheral structures  16 . A first terminal  120  of component T 7  may be coupled to ground  104  whereas a second terminal  122  of component T 7  is coupled to peripheral structures  16 . 
     In the example of  FIG. 7 , feed terminal  100 - 1  is interposed between component terminals  140  and  146 , terminal  140  is interposed between terminals  100 - 1  and  134 , terminal  134  is interposed between terminals  100 - 2  and  140 , terminal  100 - 2  is interposed between terminals  100 - 3  and  134 , terminal  100 - 3  is interposed between terminals  130  and  100 - 2 , terminal  126  is interposed between terminals  100 - 4  and  130 , and terminal  100 - 4  is interposed between terminals  120  and  126  on ground plane  104 . Similarly, terminal  142  is interposed between terminals  138  and  144 , terminal  138  is inter posed between terminals  136  and  138 , terminal  136  is interposed between terminals  132  and  138 , terminal  132  is interposed between terminals  128  and  136 , terminal  128  is interposed between terminals  124  and  123 , and terminal  124  is interposed between terminals  122  and  128  on structures  16 . This is merely illustrative and, if desired, components T 0  through T 7  may be arranged in any other desired order. 
     Adjustable components T 0 , T 2 , T 5 , and T 7  may include switchable inductors, resistors, and/or capacitors coupled in series and/or in parallel between ground  104  and peripheral structures  16 . Control circuitry  28  may adjust components T 0 , T 2 , T 5 , and/or T 7  to adjust the resonant frequency of antenna  40 L, to adjust the antenna efficiency of antenna  40 L in one or more bands, to change the location of short paths across slot  114 , or to perform other antenna adjustments. In one suitable arrangement, component T 0  may be identical to component T 7  and component T 5  may be identical to component T 2 . In another suitable arrangement, components T 0 , T 2 , T 5 , and T 7  may include different circuit components therein. 
     During operation, components T 0 , T 2 , T 3 , T 4 , T 5 , and/or T 7  may form return paths for antenna  40 L such as path  110  of  FIG. 5 . For example, return paths may be formed by components T 0 , T 2 , T 3 , T 4 , T 5 , and/or T 7  when switches in the adjustable components are closed to form a short circuit across slot  114 . Using switchable return paths and multiple selectively-activated antenna feeds may provide antenna  40  with flexibility to accommodate different loading conditions (e.g., different loading conditions that may arise due to the presence of a user&#39;s hand or other external object on various different portions of device  10  adjacent to various different corresponding portions of antenna  40 ). 
     Adjustable components such as components T 0 -T 7  may be used in adjusting the operation of antenna  40 L. Components T 0 -T 7  may include switches such as adjustable return path switches, adjustable feed path switches, switches coupled to fixed components such as inductors and/or capacitors and other circuitry for providing adjustable amounts of capacitance, adjustable amounts of inductance, open and closed circuits, etc. Adjustable components in antenna  40 L may be used to tune antenna coverage, may be used to restore antenna performance that has been degraded due to the presence of an external object such as a hand or other body part of a user, and/or may be used to adjust for other operating conditions and to ensure satisfactory operation at desired frequencies. 
     Antenna  40 L of  FIG. 7  may be used to cover radio-frequency communications in any desired communications bands. In one suitable arrangement that is sometimes described herein by example, antenna  40 L may exhibit resonances in a low band LB (e.g., a band from 600 to 960 MHz), a low midband from (e.g., a band from 1400 to 1520 MHz), a midband MB (e.g., a band from 1710 to 2170 MHz), and a high band HB (e.g., a band from 2300 to 2700 MHz). These bands may, for example, be cellular telephone communications bands handled by transceiver circuitry  47  of  FIG. 2 . 
     In one suitable arrangement, antenna  40 L may convey radio-frequency signals in one or more of these bands when a selected one of feeds F 2  and F 3  is activated. The resonance of antenna  40 L in low band LB may be associated with the distance along peripheral conductive structures  16  between the active one of antenna feeds F 2  and F 3  and the farther of gaps  18 - 1  and  18 - 2  from the active antenna feed, for example. Antenna performance in high band HB may be supported by a resonance of slot  114  between structures  16  and ground  104 . If desired, antenna  40 L may be provided with a parasitic antenna resonating element that contributes a resonance in high band HB for antenna  40 L. The parasitic antenna resonating element may, for example, be formed from conductive structures such as conductive housing structures (e.g., an integral portion of housing such as a portion of housing  12  forming ground  104 ), from parts of conductive housing structures, from parts of electrical device components, from printed circuit board traces, from strips of conductor (e.g., strips of conductor or elongated portions of ground  104  that are embedded or molded into slot  114 ), or other conductive materials. The parasitic antenna resonating element may be coupled to antenna resonating element  108  (e.g., peripheral structures  16 ) by near-field electromagnetic coupling and is used to modify the frequency response of antenna  40 L so that antenna  40 L operates in high band HB. As one example, the parasitic antenna resonating element may be based on a slot antenna resonating element structure formed using slot  114  (e.g., an open slot structure such as a slot with one open end and one closed end or a closed slot structure such as a slot that is completely surrounded by metal). 
     The resonance of antenna  40 L in low midband LMB and midband MB may be associated with the distance between the active one of antenna feeds F 2  and F 3  and a return path between peripheral structures  16  and ground  104  formed by one or more components T 0 , T 2 , T 3 , T 4 , T 5 , and T 7 . Control circuitry  28  may tune the resonance of antenna  40  within low midband LMB, midband MB, and/or high band HB by adjusting components T 0 , T 2 , T 3 , T 4 , T 5 , and/or T 7 . 
     For example, when feed F 2  is active, the length of structures  16  between feed F 2  and gap  18 - 1  may be associated with the resonance in low band LB. The length of structures  16  between feed F 2  and component T 0  may be associated with the resonance in low midband LMB and midband MB. The portion of slot  114  between feed F 2  and component T 0  or the portion of slot between feed F 2  and component T 7  may be associated with the resonance in high band HB. Adjustable components T 3 , T 4 , T 5 , and/or T 7  may be used to tune the response of antenna  40 L in low band LB whereas components T 0 , T 2 , T 5  and/or T 7  may be used to tune the response of antenna  40 L in low midband LMB, midband MB, and/or high band HB in this scenario. 
     When feed F 3  is active, the length of structures  16  between feed F 3  and gap  18 - 2  may be associated with the resonance in low band LB. Adjustable components T 3 , T 4 , T 2 , and/or T 0  may be used to tune the response of antenna  40 L in low band LB whereas components T 5 , T 2 , T 0 , and/or T 7  may be used to tune the response of antenna  40 L in low midband LMB, midband MB, and/or high band HB in this scenario. 
     The presence or absence of external objects such as a user&#39;s hand or other body part in the vicinity of antenna  40 L may affect antenna loading and therefore antenna performance. For example, in the presence of external loading, the efficiency of antenna  40 L in one or more of bands LB, LMB, MB, and HB may be degraded relative to when antenna  40 L is operated in a free space environment. 
     In practice, antenna loading may differ depending on the way in which device  10  is being held and depending on which antenna feed is active. In the example of  FIG. 7 , antenna  40 L is shown from the front of device  10  (e.g., through display  14 ). Edge  12 - 2  is associated with the right edge of housing  12  when device  10  is viewed from the front and edge  12 - 1  is associated with the left edge of housing  12  when device  10  is viewed from the front. In this example, when a user is holding device  10  in the user&#39;s right hand, the palm of the user&#39;s right hand will rest along edge  12 - 2  of housing  12  and the fingers of the user&#39;s right hand (which do not load antenna  40 L as much as the user&#39;s palm) will rest along edge  12 - 1  of housing  12 . In this situation, if antenna feed F 3  is active, loading from the user&#39;s right hand may degrade the low band resonance of antenna  40 L. Control circuitry  28  may detect the presence of the user&#39;s right hand in this scenario and, in response to such a detection, may deactivate antenna feed F 3  and instead activate antenna feed F 2 . Activating antenna feed F 2  may shift antenna current hotspots on peripheral structures  16  in the low band away from the right side (e.g., side  12 - 2 ) and towards the left side (e.g., side  12 - 1 ) of device  10 . This shift of current hotspots may reduce the loading and corresponding detuning of antenna  40 L in the low band by the user&#39;s right hand. 
     When a user is holding device  10  in the user&#39;s left hand, the palm of the user&#39;s left hand will rest along the left edge of device  10  (e.g., housing edge  12 - 1  of  FIG. 7 ) and the fingers of the user&#39;s left hand will rest along edge  12 - 2  of device  10 . In this scenario, the palm of the user&#39;s hand may load the portion of antenna  40  near to edge  12 - 1 . If antenna feed F 2  is active, loading from the user&#39;s left hand may degrade the low band resonance of antenna  40 L. Control circuitry  28  may detect the presence of the user&#39;s left hand in this scenario and, in response to such a detection, may deactivate antenna feed F 2  and instead activate antenna feed F 3 . Activating antenna feed F 3  may shift antenna current hotspots on peripheral structures  16  in the low band away from the left side  12 - 1  and towards right side  12 - 2  of device  10 . This shift of current hotspots may reduce the loading and corresponding detuning of antenna  40 L in the low band by the user&#39;s left hand. Control circuitry  28  may also adjust components T 7 , T 5 , T 4 , T 3 , T 2 , and/or T 0  to ensure that antenna  40 L remains properly tuned regardless of which antenna feed is active and regardless of which of the user&#39;s hand is being used to hold the device. 
     In some scenarios, antenna  40 L may not be capable of providing sufficient data throughput to accommodate all of the processing operations that are being performed by device  10 . In these scenarios, control circuitry  28  may adjust components T 1  through T 7  to form two separate antennas  40 L- 1  and  40 L- 2  ( FIG. 3 ) using at least some of the structures of antenna  40 L. Antennas  40 L- 1  and  40 L- 2  may subsequently convey radio-frequency signals at the same frequency using a MIMO scheme (e.g., a 4×MIMO scheme with antennas  40 U- 1  and  40 U- 2  at the opposing end of housing  12 ). This may, for example, increase the maximum data throughput of circuitry  34  by twice, four times, or more than four times the maximum data throughput of a single antenna  40 . 
     Antenna  40 L- 1  may be fed using feed F 4  whereas antenna  40 L- 2  is fed using feed F 1 . Antenna  40 L- 1  may have a main resonating element arm  108 - 1  extending from point  132  to gap  18 - 1 . Antenna  40 L- 2  may have a main resonating element arm  108 - 2  extending from point  136  to gap  18 - 2 . In order to form antennas  40 L- 1  and  40 L- 2 , control circuitry  28  may activate feeds F 4  and F 1  while deactivating feeds F 3  and F 2 . Components T 7  and/or T 5  may form return paths  110  for antenna  40 L- 1  whereas components T 2  and/or T 0  may form return paths  110  for antenna  40 L- 2 . Feed F 4  may convey radio-frequency signals (e.g., using a corresponding transmission line such as transmission line  50 - 3  of  FIG. 3 ) at one or more frequencies for antenna  40 L- 1 . Feed F 1  may concurrently convey radio-frequency signals (e.g., using a corresponding transmission line such as transmission line  50 - 4  of  FIG. 3 ) for antenna  40 L- 2  at the same frequencies as the signals conveyed by feed F 4  (e.g., using a MIMO scheme). This may serve to increase the overall data throughput of wireless circuitry  34  relative to a scenario where only antenna  40 L is used to convey radio-frequency signals within region  20  of device  10 . 
     If care is not taken, the radio-frequency signals conveyed by feed F 4  may be subject to interference with the radio-frequency signals conveyed by feed F 1  (e.g., because the signals are conveyed at the same frequencies). If care is not taken, such interference may reduce the overall antenna efficiency of antennas  40 L- 1  and  40 L- 2 , introducing errors into the transmitted or received data and/or leading to the corresponding wireless links being dropped. 
     If desired, control circuitry  28  may control adjustable components T 4  and T 3  to electromagnetically isolate antennas  40 L- 1  and  40 L- 2  (e.g., to mitigate any potential interference between signals conveyed over antennas  40 L- 1  and  40 L- 2 ). For example, control circuitry  28  may control component T 4  to short switch port P 1  to switch port P 2  and may control component T 3  to short switch port P 4  to switch port P 5 . This may serve to short any stray antenna currents from antenna  40 L- 1  to the right of feed F 4  from point  132  to point  130  on ground  104 . Similarly, antenna currents from antenna  40 L- 2  to the left of feed F 1  may be shorted from point  136  to point  134  on ground  104 . This may prevent the antenna currents from antenna  40 L- 1  from approaching or mixing with the antenna currents from antenna  40 L- 2 , thereby serving to electromagnetically isolate antennas  40 L- 1  and  40 L- 2  despite the fact that the resonating element arm for both antennas is formed from the same conductor (i.e., peripheral structure  16 ) and both antennas convey radio-frequency signals at the same frequencies. 
     A resonance of slot  114  between arm  108 - 1  and ground  104  (e.g., a parasitic element within slot  114  between arm  108 - 1  and ground  104 ) may support a resonance of antenna  40 L- 1  in high band HB. A resonance of slot  114  between arm  108 - 2  and ground  104  (e.g., a parasitic element within slot  114  between arm  108 - 2  and ground  104 ) may support a resonance of antenna  40 L- 2  in high band HB. The length of arm  108 - 1  between feed F 4  and component T 5  may support a resonance of antenna  40 L- 1  in midband MB. A length of arm  108 - 2  between component feed F 1  and component T 2  may support a resonance of antenna  40 L- 2  in midband MB. 
     If desired, control circuitry  28  may adjust components T 5  and T 2  to allow antennas  40 L- 1  and  40 L- 2  to cover frequencies towards the lower end of midband MB (e.g., towards low midband LMB). For example, in scenarios where coverage in the lower end of midband MB is not necessary, control circuitry  28  may control component T 5  to form a short circuit between point  128  and point  126  on ground  104  and may control component T 2  to form a short circuit between point  138  and point  140  on ground  104 . When configured in this way, antenna currents from feed F 4  may be shorted to ground  104  at point  126  and antenna currents from feed F 1  may be shorted to ground  104  at point  140 . 
     When cover towards the lower end of midband MB and low midband LMB is desired, control circuitry  28  may control component T 5  to form an open circuit between point  128  and point  126  on ground  104  and may control component T 2  to form an open circuit between point  138  and point  140  on ground  104 . When configured in this way, antenna currents from feed F 4  may be shorted to ground  104  at point  130  and antenna currents from feed F 1  may be shorted to ground  104  at point  134 . In this scenario, the greater length of arm  108 - 1  from feed F 4  to point  132  may support a resonance of antenna  40 L- 1  at lower frequencies in midband MB and in low midband LMB whereas the length of arm  108 - 2  from feed F 1  to point  136  may support a resonance of antenna  40 L- 2  at lower frequencies in midband MB and in low midband LMB. 
     If desired, control circuitry  28  may control adjustable inductor circuitry, adjustable capacitor circuitry, switching circuitry, or other circuitry in components T 0  and T 7  to tune the resonance of antenna  40 L- 1  the resonance of antenna  40 L- 2  in high band HB. In this way, antennas  40 L- 1  and  40 L- 2  may support communications at the same frequencies in low midband LMB, midband MB, and/or high band HB for performing MIMO operations at one or more frequencies (e.g., at least one frequency in each of bands LMB, MB, and HB). This may significantly increase the throughput of wireless circuitry relative to scenarios where one of feeds F 3  or F 4  is active for forming antenna  40 L in region  20  of device  10 . However, at the same time, antennas  40 L- 1  and  40 L- 2  may not have sufficient volume to cover low band LB. If desired, control circuitry  28  may sacrifice the throughput afforded by performing MIMO operations  40 L- 1  and  40 L- 2  by configuring adjustable components T 0 -T 7  to form antenna  40 L in scenarios where coverage in low band LB is desired. On the other hand, when a relatively high data throughput is required (e.g., for performing data intensive processing operations), control circuitry  28  may sacrifice coverage in low band LB in exchange for the higher data rates of a MIMO scheme by configuring adjustable components T 0 -T 7  to form antennas  40 L- 1  and  40 L- 2 . 
     The example of  FIG. 7  is merely illustrative. If desired, the diagram of  FIG. 7  may illustrate device antenna  40 L from the rear of device  10 . In this scenario, edge  12 - 2  is associated with the left edge of housing  12 , edge  12 - 1  is associated with the right edge of housing  12 , antenna feed F 3  may be activated when device  10  is held by the user&#39;s right hand, and antenna feed F 2  may be activated when device  10  is held by the user&#39;s left hand. Antenna ground plane  104  and slot  114  may have any desired shape. For example, ground plane  104  may have an extended portion that is closer to peripheral structures  16  than other portions of ground plane  104 . Slot  114  may, for example, have a U-shape or other meandering shape that runs around the extended portion of ground plane  104  between ground plane  104  and peripheral structures  16 . Antenna  40  may have any desired number of resonances in any desired frequency bands. In the example of  FIG. 7 , antenna  40 L is formed as the lower antenna in region  20  of device  10  ( FIG. 1 ). If desired, the structures of  FIG. 7  may also be used to form upper antennas  40 U,  40 U- 1 , and  40 U- 2  in upper antenna in region  22  of device  10  or an antenna at any other desired location within device  10 . Other structures may be used to form antennas  40 U,  40 U- 1 , and  40 U- 2  if desired. 
     The state or operating mode of the antenna structures within region  20  (and the wireless operating mode of circuitry  34  and device  10 ) may be given by the particular settings that are used for components T 0 -T 7  at a given time (e.g., which feeds are active, which return paths are used, and/or how the resonances of the antenna structures are tuned). In one suitable arrangement, the antenna structures in region  20  (e.g., device  10  or circuitry  34 ) may have at least first, second, third, and fourth operating modes or states. In the first operating mode (e.g., a so-called low band right hand mode or state), components T 0 -T 7  may be configured to form antenna  40 L and antenna feed F 2  may be used to convey radio-frequency signals over antenna  40 L. In the second operating mode (e.g., a so-called low band left hand mode or state), components T 0 -T 7  may be configured to form antenna  40 L and antenna feed F 3  may be used to convey radio-frequency signals over antenna  40 L. 
     In the third operating mode (e.g., a so-called first MIMO midband (MB) mode or state), components T 0 -T 7  may be configured to form antennas  40 L- 1  and  40 L- 2 , with feed F 4  conveying radio-frequency signals over antenna  40 L- 1  and feed F 1  conveying radio-frequency signals over antenna  40 L- 2  at one or more of the same frequencies. In the third operating mode, additional short circuit paths may be coupled into use for antennas  40 L- 1  and  40 L- 2 . In the fourth operating mode (e.g., a so-called second MIMO midband (MB) mode or state), components T 0 -T 7  may also be configured to form antennas  40 L- 1  and  40 L- 2 , with feed F 4  conveying radio-frequency signals over antenna  40 L- 1  and feed F 1  conveying radio-frequency signals over antenna  40 L- 2  at one or more of the same frequencies. However, when placed in the fourth operating mode, antennas  40 L- 1  and  40 L- 2 , the additional short circuit paths associated with the third operating mode may form open circuits. 
       FIGS. 8-11  show illustrative examples of the electrical components that may be used in forming adjustable components T 0 -T 7  of  FIG. 7  and that may be adjusted to place device  10  into a selected one of the low band left hand mode, low band right hand mode, first MIMO MB mode, and second MIMO MB mode. 
       FIG. 8  is a circuit diagram showing an illustrative switch that may be used in forming one or more of components T 0 -T 7  of  FIG. 7 . As shown in  FIG. 8 , switch  160  may be coupled between switch terminals  162  and  166 . Control circuitry  28  may adjust switch  160  using control signals  164  to place switch  160  in an open or closed state. In one suitable arrangement, switches such as switch  160  may be used to form components T 1  and T 6  of  FIG. 7  (e.g., switch terminal  162  may be coupled to feed terminal  98 - 4  or  98 - 1  whereas switch terminal  166  may be coupled to point  124  or point  142  on structures  16 ). In these scenarios, when switch  160  is turned on (closed), the corresponding feed F may be active. When switch  160  is turned off (open), the corresponding feed F may be inactive (deactivated). Switch  160  may be, for example, a single-pole single-throw (SPST) switch. 
       FIG. 9  is a circuit diagram of an illustrative switchable inductor that may be used in forming one or more of components T 0 -T 7  of  FIG. 7 . As shown in  FIG. 9 , adjustable component  168  may include inductor L 1  coupled in series with switch  176  between a first component terminal  170  and a second component terminal  172 . Switch  176  may be, for example, a single-pole single-throw (SPST) switch. Adjustable component  168  can be adjusted to produce different amounts of inductance between component terminals  170  and  172 . Component  168  may therefore sometimes be referred to herein as adjustable inductor or switchable inductor circuitry  168 . Control circuitry  28  may control switch  176  using control signals  174 . When switch  176  is placed in a closed state, inductor L 1  is switched into use and adjustable inductor  168  exhibits an inductance L 1  between component terminals  170  and  172 . When switch  176  is placed in an open state, inductor L 1  is switched out of use and adjustable inductor  168  exhibits an essentially infinite amount of inductance between component terminals  170  and  172 . 
     In one suitable arrangement, adjustable components such as adjustable component  168  may be used to form components T 7 , T 5 , T 2 , and/or T 0  of  FIG. 7  (e.g., component terminal  170  may be coupled to points  120 ,  126 ,  140 , or  146  on ground plane  104  whereas component terminal  172  may be coupled to points  122 ,  128 ,  138 , or  144  on structures  16 ). In these scenarios, when switch  176  is turned on, a return path having inductance L 1  for antenna  40 L,  40 L- 1 , or  40 L- 2  may be coupled between structures  16  and ground  104 . Switch  176  may be toggled to adjust the frequency response of antenna  40 L,  40 L- 1 , or  40 L- 2  in high band HB, midband MB, and/or low midband LMB, if desired. 
       FIG. 10  is a circuit diagram showing circuit elements that may be used in forming one or more of components T 0 -T 7  of  FIG. 7 . As shown in  FIG. 10 , adjustable component  180  may include multiple inductors that are used in providing an adjustable amount of inductance between component terminals  182  and  186  (e.g., component  168  may sometimes be referred to as an adjustable inductor or adjustable inductor circuitry). Control circuitry  28  may adjust adjustable inductor circuitry  180  to produce different amounts of inductance between component terminals  182  and  186  by controlling the state of switching circuitry such as switch  184  using control signals  188 . Switch  184  may be, for example, a single-pole double-throw (SP2T) switch. 
     Control signals on path  188  may be used to switch inductor L 2  into use between component terminals  182  and  186  while switching inductor L 3  out of use, may be used to switch inductor L 3  into use between component terminals  182  and  186  while switching inductor L 2  out of use, may be used to switch both inductors L 2  and L 3  into use in parallel between component terminals  182  and  186 , or may be used to switch both inductors L 2  and L 3  out of use to form an open circuit between component terminals  182  and  186 . 
     The switching circuitry arrangement of adjustable inductor  180  of  FIG. 10  is therefore able to produce one or more different inductance values, two or more different inductance values, three or more different inductance values, or, if desired, four different inductance values (e.g., L 2 , L 3 , L 2  and L 3  in parallel, or infinite inductance when L 2  and L 3  are switched out of use simultaneously). In one suitable arrangement, adjustable components such as adjustable component  180  may be used to form components T 7 , T 5 , T 2 , and/or T 0  of  FIG. 7  (e.g., component terminal  182  may be coupled to points  120 ,  126 ,  140 , or  146  on ground plane  104  whereas component terminal  186  may be coupled to points  122 ,  128 ,  138 , or  144  on structures  16 ). In these scenarios, when one or more of inductors L 2  and L 3  are coupled between component terminals  182  and  186 , a return path having a corresponding inductance for antenna  40 L,  40 L- 1 , or  40 L- 2  may be coupled between structures  16  and ground  104 . Switch  184  may be toggled to adjust the frequency response of antenna  40 L,  40 L- 1 , or  40 L- 2  in high band HB, midband MB, and/or low midband LMB, if desired. 
       FIG. 11  is a circuit diagram showing a three terminal component that may be used in forming one or both of components T 3  and T 4  of  FIG. 7 . As shown in  FIG. 11 , adjustable component  190  may include a first switch (e.g., an SPST switch)  198  coupled between component terminal  192  and circuit node  197 . Component  190  may include inductor L 4  coupled in series with second switch  202 , inductor L 5  coupled in series with switch  204 , inductor L 6  coupled in series with switch  206 , inductor L 7  coupled in series with switch  208 , and switch  200  coupled in parallel between component terminal  194  and circuit node  197 . Circuit node  197  may be coupled to component terminal  197 . Inductors L 4 -L 7  may be used in providing an adjustable amount of inductance between component terminals  194  and  196 . Control circuitry  28  may adjust component  190  to produce different amounts of inductance between component terminals  194  and  196  by controlling the state of switches  200 - 208 . Control circuitry  28  may close switch  198  to couple component terminal  192  to component terminal  196  (and terminal  194  when one or more of switches  200 - 208  is closed) and may open switch  198  to decouple component terminal  192  from component terminal  196 . 
     In one suitable arrangement, adjustable component  190  may be used to form components T 3  or T 4  of  FIG. 7  (e.g., component terminal  192  may form switch port P 3  coupled to feed terminal  98 - 3  or may form switch port P 6  coupled to feed  98 - 2 , component terminal  194  may form switch port P 2  coupled to ground point  130  or may form switch port P 5  coupled to ground point  134 , and component terminal  196  may form switch port P 1  coupled to resonating element point  132  or may form switch port P 4  coupled to resonating element point  136 ). In these scenarios, switches  200 - 208  may be used to provide a selected shunt inductance from the path between component terminals  192  and  196  and ground  104  when the corresponding feed F is active and/or to provide an adjustable return path inductance when the corresponding feed F is inactive. Different combinations of switches  200 - 208  may be opened or closed to adjust the shunt inductance. Adjusting the shunt inductance may, for example, be used to adjust the frequency response of antenna  40 L in low band LB if desired. 
     If desired, adjustable component  190  may have a first state at which component terminal  192  is coupled to component terminal  196 . In this first state, the corresponding feed F may be active and, if desired, switches  200 - 208  may be used to adjust the shunt inductance for the corresponding feed (e.g., to adjust the resonance of antenna  40 L in low band LB). In another suitable arrangement, each of switches  200 - 208  may be open in this state. Component  190  may have a second state at which component terminal  192  is decoupled from component terminal  196  but component terminal  194  is coupled to component terminal  196  through one or more of switches  200 - 208 . In this second state, the corresponding feed F may be inactive and a return path for antenna  40 L- 1  or  40 L- 2  may be formed between terminals  194  and  196 . If desired, switches  200 - 208  may be adjusted to tweak the inductance of the return path. Component  190  may have a third state at which all of switches  198  and  200 - 208  are open, thereby forming an open circuit between component terminals  192 ,  194 , and  196 , and deactivating the corresponding feed F. 
     The example of  FIG. 11  is merely illustrative. In general, there may be any desired number of inductors coupled in parallel between terminals  194  and  196 . The examples of  FIGS. 8-11  are merely illustrative. In general, adjustable components  160 ,  168 ,  180 , and  190  (e.g., components T 0 -T 7  of  FIG. 7 ) may each include any desired number of inductive, capacitive, resistive, and switching elements arranged in any desired manner (e.g., in series, in parallel, in shunt configurations, etc.). Control circuitry  28  may adjust components T 0 -T 7  (e.g., the switching circuitry in components  170 ,  178 ,  180 , and  190  of  FIGS. 8-11 ) to place the antenna structures in region  20  within a selected one of the low band right hand mode, low band left hand mode, first MIMO MB mode, and second MIMO MB mode. Components T 0 -T 7  of  FIG. 7  may include combinations of these components or other components arranged in any desired manner between structures  16  and ground  104 . 
     While the arrangement of  FIG. 7  may provide a satisfactory amount of isolation between antennas  40 L- 1  and  40 L- 2  when placed in the first or second MIMO MB modes of operation, if desired, antennas  40 L- 1  and  40 L- 2  may be further isolated by mechanically separating resonating element arm  108 - 1  of antenna  40 L- 1  from antenna resonating element arm  108 - 2  of antenna  40 L- 2 . 
       FIG. 12  is a diagram showing how antennas  40 L- 1  and  40 L- 2  may be formed from slot and inverted-F antenna structures and from mechanically separated portions of device housing  16 . As shown in  FIG. 12 , one or more gaps  18  ( FIG. 1 ) such as gap  18 - 3  and gap  18 - 4  may separate peripheral conductive housing structures  16  into a first segment  16 - 1  extending between gaps  18 - 1  and  18 - 3 , a second segment  16 - 2  extending between gaps  18 - 3  and  18 - 4 , and a third segment  16 - 3  extending between gaps  18 - 4  and  18 - 2 . Resonating element arm  108 - 1  of antenna  40 L- 1  may be formed from segment  16 - 1 . Resonating element arm  108 - 2  of antenna  40 L- 2  may be formed from segment  16 - 3 . 
     When configured using an arrangement of the type shown in  FIG. 12 , adjustable component T 9  may be used in place of adjustable component T 4  and adjustable component T 8  may be used in place of adjustable component T 3  of  FIG. 7 . Adjustable component T 8  may, for example, include multi-port switching circuitry having a first switch port (terminal) P 11 , a second switch port P 12 , a third switch port P 13 , and a fourth switch port P 14 . Switch port P 11  may be coupled to point  224  on segment  16 - 2  of housing structures  16 . Switch port P 14  may be coupled to point  226  on segment  16 - 3  of housing structures  16 . Switch port P 13  may be coupled to point  134  on ground plane  104 . Switch port P 12  may be coupled to feed terminal  98 - 2  of feed F 2 . 
     The switching circuitry in component T 8  may have a first state at which port P 12  is coupled to both ports P 11  and P 14 , a second state at which port P 14  is coupled to port P 13 , and a third state at which port P 11  is coupled to port P 14 . This is merely illustrative and, if desired, component T 8  may have other or additional states and may have fewer or additional ports. When component T 8  is in the first state, feed terminal  98 - 2  may be coupled to points  226  and  224  and feed F 2  may be active for antenna  40 L (e.g., antenna currents handled by feed F 2  may flow from feed terminal  98 - 2  and over both segments  16 - 2  and  16 - 3  via ports P 11  and P 14 ). When component T 8  is in the second state, a return path for antenna  40 L- 2  is formed between point  226  on segment  16 - 3  and point  134  on ground plane  104 , feed terminal  98 - 2  is decoupled from structures  16 , and feed F 2  is inactive. When component T 8  is in the third state, feed terminal  98 - 2  is decoupled from structures  16 , feed F 2  is inactive, feed F 3  may be active, and the resonating element arm for antenna  40 L (e.g., fed using feed F 3 ) may include both segments  16 - 2  and  16 - 3  (e.g., antenna currents handled by feed F 3  may flow through ports P 11  and P 14  of component T 8 ). 
     The switching circuitry in component T 9  may have a first state at which port P 9  is coupled to both ports P 7  and P 10 , a second state at which port P 7  is coupled to port P 8 , and a third state at which port P 7  is coupled to port P 10 . This is merely illustrative and, if desired, component T 9  may have other or additional states and may have fewer or additional ports. When component T 9  is in the first state, feed terminal  98 - 3  may be coupled to points  220  and  222  and feed F 3  may be active for antenna  40 L (e.g., antenna currents handled by feed F 3  may flow from feed terminal  98 - 3  over both segments  16 - 2  and  16 - 1  via ports P 7  and P 10 ). When component T 9  is in the second state, a return path for antenna  40 L- 1  is formed between point  220  on segment  16 - 1  and point  130  on ground plane  104 , feed terminal  98 - 3  is decoupled from structures  16 , and feed F 3  is inactive. When component T 9  is in the third state, feed terminal  98 - 3  is decoupled from structures  16 , feed F 3  is inactive, feed F 2  may be active, and the resonating element arm for antenna  40 L (e.g., fed using feed F 2 ) may include both segments  16 - 1  and  16 - 2  (e.g., antenna currents handled by feed F 2  may flow through ports P 7  and P 10  of component T 9 ). 
     As an example, when operated in the low band right hand operating mode, component T 8  may be placed in its first state (so that feed F 2  is active) and component T 9  may be placed in its third state to couple port P 7  to port P 10 . This may allow antenna currents for feed F 2  to flow over all three segments  16 - 1 ,  16 - 2 , and  16 - 3 . The length of segments  16 - 1  and  16 - 2  may be associated with a resonance of antenna  40 L in low band LB. Moving the low band coverage to the left of axis  133  in this example may mitigate any low band detuning due to the presence of the user&#39;s palm adjacent to side  12 - 2  of device  10 , for example. The length of segment  16 - 3  between gap  18 - 4  and gap  18 - 2  (or the length between point  226  and component T 2  or component T 0 ) may be associated with resonances of antenna  40 L in midband MB and/or low midband LMB. A portion of slot  114  extending between feed F 2  and gap  18 - 2  or between feed F 2  and gap  18 - 1  may be associated with a resonance of antenna  40 L in high band HB, as an example. 
     When operated in the low band left hand operating mode, component T 9  may be placed in the first state (so that feed F 3  is active) and component T 8  may be placed in the third state to couple port P 7  to port P 10 . This may allow antenna currents for feed F 3  to flow over all three segments  16 - 1 ,  16 - 2 , and  16 - 3 . The length of segments  16 - 2  and  16 - 3  may be associated with a resonance of antenna  40 L in low band LB. Moving the low band coverage to the right of axis  133  in this example may mitigate any low band detuning due to the presence of the user&#39;s palm adjacent to side  12 - 1  of device  10 , for example. The length of segment  16 - 1  between gap  18 - 3  and gap  18 - 1  (or the length between point  220  and component T 5  or component T 7 ) may be associated with resonances of antenna  40 L in midband MB and/or low midband LMB. A portion of slot  114  extending between feed F 3  and gap  18 - 1  or between gap  18 - 2  and feed F 3  may be associated with a resonance of antenna  40 L in high band HB, as an example. 
     When operated in the first or second MIMO MB modes of operation, both components T 9  and T 8  may be in their respective second states, forming short circuits between segment  16 - 1  and ground point  130  and between segment  16 - 3  and ground point  134 , respectively. The presence of the mechanical separation provided by gaps  18 - 3  and  18 - 4 , as well as the shorting of antenna currents for antenna  40 L- 1  to ground  104  at point  130  and antenna currents for antenna  40 L- 2  to ground  104  at point  134  may serve to electromagnetically isolate antennas  40 L- 1  and  40 L- 2  (e.g., to prevent interference between the antenna currents for antennas  40 L- 1  and  40 L- 2 ). The degree of electromagnetic isolation may, for example, be greater than in scenarios where no gaps such as gaps  18 - 3  and  18 - 4  are formed between gaps  18 - 1  and  18 - 2  (e.g., as shown in  FIG. 7 ). On the other hand, forming arm  108  of antenna  40 L without any gaps as shown in  FIG. 7  may enhance the aesthetic appearance and structural integrity of housing walls  16  relative to scenarios where gaps  18 - 3  and  18 - 4  are formed, as shown in  FIG. 12 . 
     If desired, resistive, capacitive, and/or inductive components arranged in any desired manner may also be formed within components T 9  and T 8 . For example, components T 8  and T 9  may include adjustable capacitors and/or inductors that may be adjusted by control circuitry  28  to tune the frequency responses of antennas  40 L,  40 L- 1 , and/or  40 L- 2 . In one suitable arrangement, an adjustable shunt inductance (e.g., as shown in  FIG. 11 ) may be formed in components T 9  and/or T 8  for adjusting the response of antenna  40 L in low band LB. 
     In order to ensure that antenna  40  operates satisfactorily regardless of the operating conditions of device  10  and regardless of whether a user is holding device  10  with their right or left hand, control circuitry  28  may determine which type of device operating environment is present and may adjust components T 0 -T 7  of antenna  40 L accordingly to compensate.  FIG. 13  is a flow chart of illustrative steps involved in operating device  10  to ensure satisfactory performance for antenna  40 L in all desired frequency bands of interest. The steps of  FIG. 13  may, for example, be used to adjust components T 0 -T 7  between the low band left hand mode, low band right hand mode, first MIMO MB mode, and second MIMO MB mode. 
     At step  250  of  FIG. 13 , control circuitry  28  may monitor the operating environment (state) 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 antenna impedance sensors that gather impedance data such as complex phase and magnitude information associated with antennas  40 L,  40 L- 1 , and/or  40 L- 2  using directional couplers coupled to transmission lines  50 , 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 on device  10  or that detect the presence or absence of data transmission through the 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 , or other sensors to determine how device  10  is being used. 
     If desired, control circuitry  28  may also use information from an orientation sensor such as an accelerometer in device  10  to help determine whether device  10  is being held in a position characteristic of right hand use or left hand use (or is being operated in free space). Control circuitry may also use information about a usage scenario of device  10  in determining how device  10  is being used (e.g., information identifying whether audio data is being transmitted through ear speaker  26  of  FIG. 1 , information identifying whether a telephone call is being conducted, information identifying whether a microphone on device  10  is receiving voice signals, etc.). 
     If desired, control circuitry  28  may identify frequency bands that are to be used for wireless communications. For example, control circuitry  28  may identify the frequency bands that are assigned to device  10  for communications (e.g., by external equipment such as a wireless base station or access point or by communications software running on control circuitry  28 ). As another example, control circuitry  28  may identify the frequency bands that are to be used based on the radio-frequency performance of device  10  (e.g., one or more frequency bands at which device  10  has optimal performance at a given time). 
     If desired, control circuitry  28  may identify a data throughput, data rate, or bandwidth requirement for device  10 . Such a requirement may, for example, be dictated by operations that are being performed by device  10 . For example, device  10  may identify when processing operations or other operations are being performed that may require more data be received from external equipment than other operations (e.g., streaming online video, performing complex cloud processing and storage operations, etc.). In general, any desired combination of one or more of these types of information may be processed by control circuitry  28  to identify how device  10  is being used (i.e., to identify the operating environment of device  10 ). 
     At step  252 , control circuitry  28  may adjust the configuration of components T 0 -T 7  based on the current operating environment of device  10  (e.g., based on data or information gathered while processing step  250 ). For example, control circuitry  28  may place components T 0 -T 7  in an optimal one of the low band left hand mode, low band right hand mode, first MIMO MB mode, and second MIMO MB mode based on the information gathered while processing step  250 . By configuring components T 0 -T 7  in one of these operating modes, control circuitry  28  may ensure that wireless circuitry  34  operates satisfactorily regardless of how the user is holding device  10 , regardless of the frequency bands that are to be used, and regardless of whether device  10  is performing operations that require a relatively low data rate or a relatively high data rate such as a data rate afforded by operating under a MIMO scheme. 
     A state diagram showing illustrative operating modes for device  10  (e.g., for circuitry  34  or the antenna structures in region  20  of device  10 ) is shown in  FIG. 14 . As shown in  FIG. 14 , device  10  may be operable in a low band right hand mode  270 , a low band left hand head mode  272 , a first MIMO MB mode  274 , and a second MIMO MB mode  276 . Control circuitry  28  may identify which mode is to be used based on the monitored operating conditions of device  10  (e.g., using the sensor data and other information gathered while processing step  250  of  FIG. 13 ) and may adjust tunable components T 0 -T 7  of  FIGS. 7 and 12  to place device  10  in the corresponding operating mode. 
     When operating in low band right hand mode  270 , control circuitry  28  may enable antenna feed F 2  and may disable antenna feeds F 1 , F 3 , and F 4 . For example, control circuitry  28  may control component T 3  of  FIG. 7  to couple port P 6  to port P 4  and may control component T 4  to form an open circuit between terminals P 1 , P 2 , and P 3 . Feed terminal  98 - 2  may thereby be coupled to point  136  and may convey radio-frequency signals for antenna  40 L. Control circuitry  28  may control components T 1 , T 5 , and T 6  to form open circuits between ground  104  and structures  16  (e.g., by opening corresponding switches of the types shown in  FIGS. 8-11 ). Control circuitry may control component T 2  to form a short circuit to ground  104  (e.g., by closing switches of the types shown in  FIGS. 8-11 ). In scenarios where splits  18 - 3  and  18 - 4  are formed in structures  16  ( FIG. 12 ), control circuitry  28  may control component T 8  to couple port P 12  to ports P 11  and P 14  and may control component T 9  to couple port P 7  to port P 10 . Component T 0  may be placed in any desired state (e.g., because antenna currents are shorted to ground by element T 2  prior to reaching component T 0 ). 
     In this operating mode, antenna  40 L may exhibit a resonance in low band LB associated with the length of structures  16  between feed F 2  and gap  18 - 1 , a resonance in midband MB and/or low midband LMB associated with the length of structures  16  between feed F 2  and component T 2 , and/or a resonance in high band HB associated with slot  114 . Control circuitry  28  may adjust the state of component T 7  to tune the response of antenna  40 L in high band HB. Control circuitry  28  may adjust the state of component T 2  (e.g., by adjusting an inductance provided by component T 2  as shown in  FIGS. 9 and 10 ) to tune the response of antenna  40 L in midband MB and/or low midband LMB. Control circuitry  28  may adjust a shunt inductance of component T 3  (e.g., as shown in  FIG. 11 ) to tune the response of antenna  40 L in low band LB if desired. 
     When configured in low band right hand mode  270 , antenna  40 L may convey radio-frequency signals in low band LB, low midband LMB, midband MB, and/or high band HB with satisfactory antenna efficiency, even if a user&#39;s hand (e.g., right hand) loads antenna  40 L from side  12 - 2  of housing  12 . However, if a user&#39;s hand (e.g., left hand) loads antenna  40 L from side  12 - 1  of housing  12 , antenna  40 L may have reduced antenna efficiency when conveying radio-frequency signals in mode  270 . When configured in mode  270 , antenna  40 U at the opposing end of device  10  may operate at the same frequencies as antenna  40 L or at different frequencies  40 L. If antenna  40 L and  40 U operate at one or more of the same frequencies, antennas  40 U and  40 L may perform communications using a MIMO scheme (e.g., a 2×MIMO scheme) at one or more of those frequencies to increase the data throughput of circuitry  34  relative to scenarios where only a single antenna is used (e.g., to twice the data rate of the single antenna or greater, depending on the number of frequencies used for the MIMO scheme). 
     Control circuitry  28  may place device  10  into mode  270  in response to certain operating conditions of device  10  (e.g., as determined using the sensor data and other information gathered while processing step  250  of  FIG. 13 ). As one example, control circuitry  28  may place device  10  in one of modes  270  and  272  in response to determining that communications in low band LB is desired (e.g., when a frequency in low band LB is assigned to device  10  for communications using external base station equipment or by software on running on circuitry  28 , when sensor circuitry identifies that radio-frequency performance of circuitry  34  is optimized in low band LB, etc.). Sensor circuitry such as proximity sensor circuitry or antenna impedance measurement circuitry may subsequently determine whether a user&#39;s hand or other external object is adjacent to side  12 - 1  or side  12 - 2  of housing  12 . In response to determining that the user&#39;s hand is adjacent to side  12 - 2 , control circuitry  28  may place device  10  in operating mode  270 . In response to determining that the user&#39;s hand is adjacent to side  12 - 1 , control circuitry  28  may place device  10  in operating mode  272 . 
     In another example, control circuitry  28  may identify a data throughput requirement for device  10 . The data throughput requirement may, for example, be determined by the processing operations being performed by device  10  (e.g., some operations may require more wireless data be conveyed per second with external equipment than others). In response to determining that a relatively low data throughput requirement is present (e.g., that the required data throughput, data rate, or data bandwidth is less than a threshold value), control circuitry  28  may place device  10  in one of modes  270  or  272 . Operating in modes  270  and  272  may, for example, involve greater antenna efficiency in one or more frequency bands than in modes where antennas  40 L- 1  and  40 L- 2  are used (e.g., because antenna  40 L occupies a larger volume than antennas  40 L- 1  or  40 L- 2 ). Sensor circuitry such as proximity sensor circuitry or antenna impedance measurement circuitry may subsequently determine whether a user&#39;s hand or other external object is adjacent to side  12 - 1  or side  12 - 2  of housing  12 . In response to determining that the user&#39;s hand is adjacent to side  12 - 2 , control circuitry  28  may place device  10  in operating mode  270 . In response to determining that the user&#39;s hand is adjacent to side  12 - 1 , control circuitry  28  may place device  10  in operating mode  272 . 
     When operating in low band left hand mode  272 , control circuitry  28  may enable antenna feed F 3  and may disable antenna feeds F 1 , F 2 , and F 4 . For example, control circuitry  28  may control component T 4  of  FIG. 7  to couple port P 3  to port P 1  and may control component T 3  to form an open circuit between terminals P 4 , P 5 , and P 6 . Feed terminal  98 - 3  may thereby be coupled to point  132  and may convey radio-frequency signals for antenna  40 L. Control circuitry  28  may control components T 1 , T 2 , and T 6  to form open circuits between ground  104  and structures  16  (e.g., by opening corresponding switches such as the switches shown in  FIGS. 8-11 ). Control circuitry may control component T 5  to form a short circuit to ground  104  (e.g., by closing switches of the types shown in  FIGS. 8-11 ). In scenarios where splits  18 - 3  and  18 - 4  are formed in structures  16  ( FIG. 12 ), control circuitry  28  may control component T 9  to couple port P 9  to ports P 7  and P 10  and may control component T 8  to couple port P 11  to port P 14 . Component T 7  may be placed in any desired state (e.g., because antenna currents are shorted to ground by element T 5  prior to reaching component T 7 ). 
     In this operating mode, antenna  40 L may exhibit a resonance in low band LB associated with the length of structures  16  between feed F 3  and gap  18 - 2 , a resonance in midband MB and/or low midband LMB associated with the length of structures  16  between feed F 3  and component T 5 , and/or a resonance in high band HB associated with slot  114 . Control circuitry  28  may adjust the state of component T 0  to tune the response of antenna  40 L in high band HB. Control circuitry  28  may adjust the state of component T 5  (e.g., by adjusting an inductance provided by component T 5  as shown in  FIGS. 9 and 10 ) to tune the response of antenna  40 L in midband MB and/or low midband LMB. Control circuitry  28  may adjust a shunt inductance of component T 4  (e.g., as shown in  FIG. 11 ) to tune the response of antenna  40 L in low band LB if desired. 
     When configured in low band left hand mode  272 , antenna  40 L may convey radio-frequency signals in low band LB, low midband LMB, midband MB, and/or high band HB with satisfactory antenna efficiency, even if a user&#39;s hand (e.g., left hand) loads antenna  40 L from side  12 - 1  of housing  12 . However, if a user&#39;s hand (e.g., right hand) loads antenna  40 L from side  12 - 2  of housing  12 , antenna  40 L may have reduced antenna efficiency when conveying radio-frequency signals in mode  272 . When configured in mode  272 , antenna  40 U at the opposing end of device  10  may operate at the same frequencies as antenna  40 L or at different frequencies  40 L. If antenna  40 L and  40 U operate at one or more of the same frequencies, antennas  40 U and  40 L may perform communications using a MIMO scheme (e.g., a 2×MIMO scheme) at one or more of those frequencies to increase the data throughput of circuitry  34  relative to scenarios where only a single antenna is used (e.g., to twice the data rate of the single antenna or greater, depending on the number of frequencies used for the MIMO scheme). 
     Control circuitry  28  may place device  10  into mode  272  in response to certain operating conditions of device  10  (e.g., as determined using the sensor data and other information gathered while processing step  250  of  FIG. 13 ). As one example, control circuitry  28  may place device  10  into mode  272  in response to determining that communications in low band LB is desired or that a relatively high data throughput associated with 4×MIMO operations is not required and in response to determining that the user&#39;s hand or other external objects are adjacent to side  12 - 1  of housing  12 , for example. 
     When in first MIMO MB mode  274 , control circuitry  28  may enable antenna feeds F 1  and F 4  and may disable antenna feeds F 2  and F 3 . This may configure the structures in region  20  to form antennas  40 L- 1  and  40 L- 2  instead of a single antenna  40 L. For example, control circuitry  28  may control component T 4  of  FIG. 7  to short port P 2  to port P 1  and may control component T 3  to short port P 4  to P 5 . Forming return paths to points  130  and  134  in this way may short any stray antenna currents from feeds F 1  and F 2  to ground  104 , thereby serving to electromagnetically isolate antennas  40 L- 1  and  40 L- 2  despite antennas  40 L- 1  and  40 L- 2  having resonating element arms formed from the same continuous piece of conductor  16 . 
     Control circuitry  28  may control component T 1  to short terminal  98 - 1  to point  142  and may control component T 6  to short terminal  98 - 4  to point  124 . This may allow antenna currents conveyed by feed F 4  of antenna  40 L- 1  to flow over resonating element arm  108 - 1  and may allow antenna currents conveyed by feed F 1  of antenna  40 L- 2  to flow over resonating element arm  108 - 2 . Control circuitry  28  may control component T 2  to form a short circuit to ground  104  for antenna  40 L- 2  (e.g., by closing switches of the types shown in  FIGS. 8-11 ). Control circuitry  28  may control component T 5  to form a short circuit to ground  104  for antenna  40 L- 1 . In scenarios where splits  18 - 3  and  18 - 4  are formed in structures  16  ( FIG. 12 ), control circuitry  28  may control component T 9  to couple port P 7  to port P 8  and may control component T 8  to couple port P 13  to port P 14  (e.g., to form isolating return paths between segments  16 - 1  and  16 - 3  and ground  104 ). 
     In this operating mode, antennas  40 L- 1  and  40 L- 2  may have insufficient volume for covering low band LB. Antennas  40 L- 1  and  40 L- 2  may, however, concurrently convey radio-frequency signals at the same frequencies in midband MB and/or high band HB. For example, the response of antenna  40 L- 1  in midband MB may be associated with the length of structures  16  between feed F 4  and the return path formed by component T 5 . The response of antenna  40 L- 2  in midband MB may be associated with the length of structures  16  between feed F 1  and the return path formed by component T 2 . The response of antenna  40 L- 1  in high band HB may be associated with a portion of slot  114  between arm  108 - 1  and ground  104 . The response of antenna  40 L- 2  in high band HB may be associated with a portion of slot  114  between arm  108 - 2  and ground  104 . Control circuitry  28  may adjust the state of component T 0  to tune the response of antenna  40 L- 1  in high band HB and may adjust the state of component T 7  to tune the response of antenna  40 L- 2  in high band HB. Control circuitry  28  may adjust the state of component T 5  to tune the response of antenna  40 L- 1  in midband MB and may adjust the state of component T 2  to tune the response of antenna  40 L- 2  in midband MB, if desired. 
     When configured in first MIMO MB mode  274 , antennas  40 L- 1  and  40 L- 2  may concurrently convey radio-frequency signals in midband MB and/or high band HB using a MIMO scheme and with a greater throughput than when antenna  40 L is used. When configured in mode  274 , antennas  40 U- 1  and  40 U- 2  at the opposing end of device  10  may operate at the same frequencies as antennas  40 L- 1  and  40 L- 2  or at different frequencies. If antennas  40 L- 1 ,  40 L- 2 ,  40 U- 1 , and  40 U- 2  operate at one or more of the same frequencies, antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , and  40 L- 2  may concurrently convey signals at the same frequencies using a 4×MIMO scheme. If antennas  40 U- 1  and  40 U- 2  (or antenna  40 U) operate at different frequencies from antennas  40 L- 1  and  40 L- 2 , antennas  40 L- 1  and  40 L- 2  may concurrently convey signals at the same frequencies using a 2×MIMO scheme if desired. 
     Control circuitry  28  may place device  10  into mode  274  in response to certain operating conditions of device  10  (e.g., as determined using the sensor data and other information gathered while processing step  250  of  FIG. 13 ). As one example, control circuitry  28  may place device  10  into modes  274  or  276  in response to determining that communications in low band LB are not desired and/or that a relatively high data throughput is required (e.g., in scenarios where the processing operations of circuitry  28  require a greater data throughput than a predetermined threshold value that cannot be satisfied using only a single antenna). Control circuitry  28  may place device  10  in mode  274  in response to determining that short circuits between points  128  and  126  and between points  140  and  138  are desired (e.g., when communications towards the lower end of midband MB and low midband LMB are not required). 
     When in second MIMO MB mode  276 , control circuitry  28  may enable antenna feeds F 1  and F 4  and may disable antenna feeds F 2  and F 3 . This may configure the structures in region  20  to form antennas  40 L- 1  and  40 L- 2  instead of a single antenna  40 L. For example, control circuitry  28  may control component T 4  of  FIG. 7  to short port P 2  to port P 1  and may control component T 3  to short port P 4  to P 5 . Forming return paths to points  130  and  134  in this way may short antenna currents from feeds F 1  and F 2  to ground  104 , thereby serving to electromagnetically isolate antennas  40 L- 1  and  40 L- 2  despite antennas  40 L- 1  and  40 L- 2  having resonating element arms formed from the same continuous piece of conductor  16 . 
     Control circuitry  28  may control component T 1  to short terminal  98 - 1  to point  142  and may control component T 6  to short terminal  98 - 4  to point  124 . This may allow antenna currents conveyed by feed F 4  of antenna  40 L- 1  to flow over resonating element arm  108 - 1  and may allow antenna currents conveyed by feed F 1  of antenna  40 L- 2  to flow over resonating element arm  108 - 2 . Control circuitry  28  may control component T 2  to form an open circuit between ground  104  and structures  16  (e.g., by opening switches of the types shown in  FIGS. 8-11 ). Control circuitry  28  may control component T 5  to form an open circuit between ground  104  and structures  16 . In scenarios where splits  18 - 3  and  18 - 4  are formed in structures  16  ( FIG. 12 ), control circuitry  28  may control component T 9  to couple port P 7  to port P 8  and may control component T 8  to couple port P 13  to port P 14  (e.g., to form isolating return paths between segments  16 - 1  and  16 - 3  and ground  104 ). 
     In this operating mode, antennas  40 L- 1  and  40 L- 2  may have insufficient volume for covering low band LB. Antennas  40 L- 1  and  40 L- 2  may, however, concurrently convey radio-frequency signals in low midband LMB, midband MB and/or high band HB. For example, the response of antenna  40 L- 1  in low midband LMB and midband MB may be associated with the length of structures  16  between feed F 4  and the return path formed by component T 4  (or T 9  in the example of  FIG. 12 ). The response of antenna  40 L- 2  in low midband LMB and midband MB may be associated with the length of structures  16  between feed F 1  and the return path formed by component T 3  (or T 8  in the example of  FIG. 12 ). The response of antenna  40 L- 1  in high band HB may be associated with a portion of slot  114  between arm  108 - 1  and ground  104 . The response of antenna  40 L- 2  in high band HB may be associated with a portion of slot  114  between arm  108 - 2  and ground  104 . Control circuitry  28  may adjust the state of component T 0  to tune the response of antenna  40 L- 1  in high band HB and may adjust the state of component T 7  to tune the response of antenna  40 L- 2  in high band HB. Control circuitry  28  may adjust inductance and/or capacitance of component T 4  (T 9 ) to tune the response of antenna  40 L- 1  in low midband LMB and midband MB and may adjust the inductance and/or capacitance of component T 3  (T 8 ) to tune the response of antenna  40 L- 2  in low midband LMB and midband MB if desired. 
     When configured in second MIMO MB mode  276 , antennas  40 L- 1  and  40 L- 2  may concurrently convey radio-frequency signals in low midband LMB, midband MB, and/or high band HB using a MIMO scheme and with a greater throughput than when antenna  40 L is used. When configured in mode  276 , antennas  40 U- 1  and  40 U- 2  at the opposing end of device  10  may operate at the same frequencies as antennas  40 L- 1  and  40 L- 2  or at different frequencies. If antennas  40 L- 1 ,  40 L- 2 ,  40 U- 1 , and  40 U- 2  operate at one or more of the same frequencies, antennas  40 U- 1 ,  40 U- 2 ,  40 L- 1 , and  40 L- 2  may concurrently convey signals at the same frequencies using a 4×MIMO scheme. If antennas  40 U- 1  and  40 U- 2  (or antenna  40 U) operate at different frequencies from antennas  40 L- 1  and  40 L- 2 , antennas  40 L- 1  and  40 L- 2  may concurrently convey signals at the same frequencies using a 2×MIMO scheme if desired. 
     Control circuitry  28  may place device  10  into mode  276  in response to detecting certain operating conditions of device  10  (e.g., as determined using the sensor data and other information gathered while processing step  250  of  FIG. 13 ). As one example, control circuitry  28  may place device  10  into mode  276  in response to determining that communications in low band LB are not desired (or that a data throughput that is greater than supported by a single antenna  40 L is required) or in response to determining that communications in midband MB is required, and in response to determining that open circuits are desired between points  128  and  126  and between points  138  and  140  (e.g., when device  10  is assigned a frequency near the lower end of band MB or in band LMB for communications). In this way, control circuitry  28  may switch device  10  between modes  270 ,  272 ,  274 , and  276  to ensure that device  10  has satisfactory data throughput and antenna efficiency regardless of the operating requirements and environment of device  10 . 
     The example of  FIG. 14  is merely illustrative. If desired, the antenna structures in region  20  may be operated in more than four operating modes or fewer than four operating modes. Similar operating modes may be used for operating antennas  40 U,  40 U- 1 , and  40 U- 2  of  FIG. 3  or different operating modes may be used for antennas  40 U,  40 U- 1 , and  40 U- 2  if desired. 
       FIG. 15  is a graph in which antenna performance (standing wave ratio) has been plotted as a function of operating frequency f for antennas  40 L,  40 L- 1 , and  40 L- 2  of  FIGS. 7 and 12 . As shown in  FIG. 15 , curve  280  plots the performance of antenna  40 L when device  10  is placed in low band right hand mode  270  or low band left hand mode  272  of  FIG. 14 . When operating in modes  272  or  270 , antenna  40 L may exhibit resonances (responses) at frequencies in low band LB, low midband LMB, midband MB, and high band HB. The response of antenna  40 L in low band LB may be adjusted using adjustable components T 3 , T 4 , T 8 , T 9 , or other components as shown by arrow  286 . The response of antenna  40 L in high band HB may be adjusted using adjustable components T 0  or T 7  as shown by arrow  288 . 
     Curve  282  plots the performance of either of antennas  40 L- 1  and  40 L- 2  when operating using first MIMO MB mode  274  of  FIG. 14 . When operating in mode  274 , antennas  40 L- 1  and  40 L- 2  may exhibit resonances in midband MB and high band HB. The response of antenna  40 L- 1  in high band HB may be adjusted using adjustable component T 7  and the response of antenna  40 L- 2  in high band HB may be adjusted using adjustable component T 0  as shown by arrow  286 . 
     Dashed curve  284  plots the performance of either of antennas  40 L- 1  and  40 L- 2  when operating using second MIMO MB mode  276  of  FIG. 14 . When operating in mode  276 , antennas  40 L- 1  and  40 L- 2  may exhibit resonances in midband MB with a tweaked response relative to first MIMO MB mode  276  (e.g., extending the response towards the lower end of midband MB) and in high band HB. The response of antenna  40 L- 1  in high band HB may be adjusted using adjustable component T 7  and the response of antenna  40 L- 2  in high band HB may be adjusted using adjustable component T 0  as shown by arrow  286 . 
     In the example of  FIG. 15 , low band LB extends from 600 MHz to 960 MHz, low midband LMB extends from 1500 MHz to 1700 MHz, midband MB extends from 1700 MHz to 2170 MHz, and high band HB extends from 2300 MHz to 2700 MHz. This is merely illustrative and, in general, bands LB, LMB, MB, and HB may include any desired frequencies (e.g., where low midband LMB is higher than low band LB, midband MB is higher than low midband LMB, and high band HB is higher than midband MB). In general, performance curves  280 ,  282 , and  284  may have any desired shape. Antennas  40 L,  40 L- 1 , and  40 L- 2  may exhibit responses in more than four frequency bands, in fewer than three frequency bands, or in any other desired frequency bands if desired. Antennas  40 L,  40 L- 1 , and  40 L- 2  may exhibit narrowband resonances within bands LB, low midband LMB, midband MB, and/or high band HB or may exhibit broadband resonances extending across substantially all of the respective bands LB, LMB, MB, and/or HB. Similar performance curves may also be used to characterize antennas  40 U,  40 U- 1 , and  40 U- 2  of  FIG. 3  if desired. 
     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: 20170720
Publication Date: 20191112
Grant Date: 20191112
Priority Date: 20170720
Inventors: AYALA VAZQUEZ, ENRIQUE
JIN, NANBO
HU, HONGFEI
WANG, HAN
IRCI, Erdinc
TONG, ERICA J.
MOW, MATTHEW A.
TSAI, MING-JU
HAN, LIANG
ATMATZAKIS, GEORGIOS
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/342", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/25", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/242", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/342", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/521", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/0006", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2258", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/0006", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/342", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/0413", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/0404", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 64951543