PATENT DOCUMENT

Publication Number: US-10944153-B1
Application Number: US-201916556026-A
Country: US
Kind Code: B1

Title: Electronic devices having multi-band antenna structures

Abstract:
An electronic device may be provided with an antenna having a resonating element. The resonating element may have first and second arms extending from opposing sides of a feed. The first arm may have a fundamental mode that radiates in a first communications band such as a 5.0 GHz wireless local area network band. The second arm may have a fundamental mode that radiates in a second communications band such as one or more cellular ultra-high bands. The second resonating element arm may have a harmonic mode that radiates in first and second ultra-wideband (UWB) communications bands. The antenna may include a tunable component that is adjustable between first and second states. The second arm may radiate in the first UWB communications band while the tunable component is in the first state and in the second UWB communications band while the tunable component is in the second state.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 an antenna having an antenna feed and first and second resonating element arms extending from opposing sides of the antenna feed; 
 a first radio-frequency transceiver coupled to the antenna feed and configured to convey, using the antenna, first non-ultra-wideband signals in a first communications band, the first resonating element arm being configured to radiate in the first communications band; 
 a second radio-frequency transceiver coupled to the antenna feed and configured to convey, using the antenna, second non-ultra-wideband signals in a second communications band that is lower than the first communications band, the second resonating element arm being configured to radiate in the second communications band; and 
 a third radio-frequency transceiver coupled to the antenna feed and configured to convey, using the antenna, ultra-wideband signals in an ultra-wideband communications band that is higher than the first communications band, the second resonating element arm being configured to radiate in the ultra-wideband communications band. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the second resonating element arm has a fundamental mode configured to radiate in the second communications band and a harmonic mode configured to radiate in the ultra-wideband communications band. 
     
     
       3. The electronic device defined in  claim 1 , wherein the antenna further comprises:
 ground structures; and 
 a tunable component coupled between the second resonating element arm and the ground structures, wherein the tunable component is adjustable between first and second tuning states and the second resonating element arm is configured to radiate in the ultra-wideband communications band while the tunable component is in the first tuning state. 
 
     
     
       4. The electronic device defined in  claim 3 , wherein the third radio-frequency transceiver is configured to convey, using the antenna, additional ultra-wideband signals in an additional ultra-wideband communications band that is higher than the first communications band and lower than the ultra-wideband communications band, the second resonating element arm being configured to radiate in the additional ultra-wideband communications band while the tunable component is in the second tuning state. 
     
     
       5. The electronic device defined in  claim 4 , wherein the ultra-wideband communications band comprises a first frequency between 7750 MHz and 8250 MHz and the additional ultra-wideband communications band comprises a second frequency between 6250 MHz and 6750 MHz. 
     
     
       6. The electronic device defined in  claim 5 , wherein the first non-ultra-wideband signals comprise wireless local area network (WLAN) signals and the first communications band comprises a third frequency between 5180 MHz and 5850 MHz. 
     
     
       7. The electronic device defined in  claim 6 , wherein the second non-ultra-wideband signals comprise cellular telephone signals and the second communications band comprises a fourth frequency between 3400 MHz and 3700 MHz. 
     
     
       8. The electronic device defined in  claim 4 , wherein the tunable component comprises a capacitor and a switch coupled in series between the second resonating element arm and the ground structures, the switch being open in the first tuning state and closed in the second tuning state. 
     
     
       9. The electronic device defined in  claim 8 , wherein the tunable component further comprises:
 an additional capacitor coupled in parallel with the capacitor between the second resonating element arm and the ground structures; and 
 an inductor coupled in parallel with the capacitor and the additional capacitor between the second resonating element arm and the ground structures. 
 
     
     
       10. The electronic device defined in  claim 9 , wherein the tunable component further comprises an additional switch coupled in series with the additional capacitor between the second resonating element arm and the ground structures. 
     
     
       11. The electronic device defined in  claim 8 , further comprising:
 an impedance matching network coupled to the antenna feed, the impedance matching network comprising:
 an additional capacitor coupled between the second resonating element arm and the ground structures, and 
 an inductor coupled between the second resonating element arm and the ground structures, the antenna feed being interposed between the additional capacitor and the inductor. 
 
 
     
     
       12. The electronic device defined in  claim 4 , wherein the tunable component comprises an inductor and a switch coupled in series between the second resonating element arm and the ground structures, the switch being closed in the first tuning state and open in the second tuning state. 
     
     
       13. The electronic device defined in  claim 1 , further comprising:
 ground structures; 
 peripheral conductive housing structures that are separated from the ground structures by a slot, wherein the first and second resonating element arms of the antenna overlap the slot; and 
 an additional antenna having a third resonating element arm formed from a segment of the peripheral conductive housing structures, an additional antenna feed coupled to the segment, and a tunable component coupled between the segment and the ground structures, wherein the second radio-frequency transceiver is coupled to the additional antenna feed and configured to convey, using the additional antenna, third non-ultra-wideband signals in a third communications band that is lower than the second communications band, the third resonating element arm being configured to radiate in the third communications band. 
 
     
     
       14. The electronic device defined in  claim 13 , wherein the second resonating element arm is configured to induce, on a portion of the segment, an antenna current in the ultra-wideband communications band, the portion of the segment being configured to contribute to radiation by the antenna in the ultra-wideband communications band. 
     
     
       15. The electronic device defined in  claim 13 , wherein the electronic device has a front face and a rear face, the electronic device further comprising:
 a display at the front face and mounted to the peripheral conductive housing structures; 
 a housing wall at the rear face and mounted to the peripheral conductive housing structures; and 
 first, second, and third ultra-wideband antennas aligned with respective first, second, and third openings in the ground structures, wherein the third radio-frequency transceiver is configured to transmit the ultra-wideband signals through the housing wall at the rear face using the first, second, and third ultra-wideband antennas, the antenna being configured to receive the ultra-wideband signals through the housing wall at the rear face and a portion of the display at the front face. 
 
     
     
       16. The electronic device defined in  claim 1 , wherein the opposing sides of the antenna feed comprise a first side of the antenna feed, and the first resonating element arm comprises a first segment extending from the first side of the antenna feed, a second segment having a first end extending at a non-parallel angle from the first segment, and a third segment extending at a non-parallel angle from a second end of the second segment. 
     
     
       17. The electronic device defined in  claim 16 , wherein the antenna comprises:
 a return path that couples the first segment to the antenna ground, wherein the opposing sides of the antenna feed comprise a second side of the antenna feed, and the second resonating element arm has a fourth segment that extends from the second side of the antenna feed, a fifth segment having a first end extending at a non-parallel angle from the fourth segment, and a sixth segment extending at a non-parallel angle from a second end of the fifth segment, the fifth segment being separated from an end of the third segment by a first gap, and the sixth segment being separated from an edge of the third segment by a second gap. 
 
     
     
       18. The electronic device defined in  claim 1 , wherein the second antenna resonating element has a first segment that extends from the antenna feed, a second segment having a first end extending at non-parallel angle from the first segment, and a third segment extending at a non-parallel angle from a second end of the second segment. 
     
     
       19. The electronic device defined in  claim 18 , wherein the antenna comprises:
 a tunable component coupling an antenna ground for the antenna to a segment selected from the group consisting of: the first segment and the second segment. 
 
     
     
       20. The electronic device defined in  claim 1 , wherein the electronic device has a front face and a rear face, the electronic device further comprising:
 peripheral housing structures; 
 a display at the front face and mounted to the peripheral housing structures; and 
 a housing wall at the rear face and mounted to the peripheral housing structures, wherein the third radio-frequency transceiver is configured to convey, using the antenna, the ultra-wideband signals through the housing wall and through an inactive area of the display.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices are often provided with wireless communications capabilities. To satisfy consumer demand for small form factor electronic devices, manufacturers are continually striving to implement wireless circuitry such as antenna components using compact structures. 
     At the same time, larger antenna volumes generally allow antennas to exhibit greater efficiency bandwidth. In addition, because antennas have the potential to interfere with each other and with other components in a wireless device, care must be taken when incorporating antennas into an electronic device to ensure that the antennas and wireless circuitry are able to exhibit satisfactory performance over a wide range of operating frequencies. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry and peripheral conductive housing structures. A display may be located at a front face of the device whereas a housing wall is located at a rear face of the device. The wireless circuitry may include first, second, third, fourth, and fifth antennas, a wireless local area network (WLAN) transceiver, a cellular telephone transceiver, and an ultra-wideband (UWB) transceiver. 
     The third, fourth, and fifth antennas may be UWB antennas that are aligned with respective openings in ground structures for the device. The third, fourth, and fifth antennas may convey UWB signals for the UWB transceiver in first and second UWB communications bands (e.g., 6.5 GHz and 8.0 GHz bands) through the housing wall. The second antenna may have a resonating element arm formed from a segment of the peripheral conductive housing structures and a return path coupled between the segment and the ground structures. The second antenna may convey non-UWB signals for the WLAN transceiver and/or the cellular telephone transceiver. The first antenna may have an antenna resonating element that overlaps a slot between the segment and the ground structures. The first antenna may transmit and receive non-UWB signals such as WLAN signals and cellular ultra-high band signals through the housing wall and the slot, through an inactive area of a display for the device, and/or through a gap in the peripheral conductive housing structures. The first antenna may also concurrently receive UWB signals for the UWB transceiver in one of the first and second UWB communications bands through these portions of the device. 
     The antenna resonating element may have a first resonating element arm and a second resonating element arm extending from opposing sides of an antenna feed. The first resonating element arm may be coupled to the ground structures by a return path. The first resonating element arm may have a fundamental mode that radiates in a first non-UWB communications band such as a 5.0 GHz WLAN communications band. The second resonating element arm may have a fundamental mode that radiates in a second non-UWB communications band such as one or more cellular ultra-high bands. The second resonating element arm may have a harmonic mode that radiates in the first and second UWB communications bands. Portions of the segment of the peripheral conductive housing structures and/or the return path of the second antenna may also contribute to radiation by the first antenna in the first and second UWB communications bands. 
     The first antenna may include a tunable component that is adjustable between first and second tuning states. The tunable component may be coupled between the second resonating element arm and the ground structures or between the second resonating element arm and the return path for the second antenna. The harmonic mode of the second resonating element arm may radiate in the first UWB communications band while the tunable component is in the first tuning state. The harmonic mode of the second resonating element arm may radiate in the second UWB communications band while the tunable component is in the second tuning state. The tunable component may include one or more switchable capacitors or a switchable inductor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with some embodiments. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with some embodiments. 
         FIG. 3  is a schematic diagram of illustrative wireless circuitry in accordance with some embodiments. 
         FIG. 4  is a diagram of an illustrative antenna having an antenna resonating element arm and an antenna ground in accordance with some embodiments. 
         FIG. 5  is a top view of illustrative antenna structures for covering multiple frequency bands in an electronic device in accordance with some embodiments. 
         FIG. 6  is a top view of an illustrative antenna for covering multiple frequency bands within a confined volume in accordance with some embodiments. 
         FIGS. 7 and 8  are circuit diagrams of illustrative tuning components that may be integrated within an antenna of the type shown in  FIG. 6  in accordance with some embodiments. 
         FIG. 9  is a circuit diagram of an illustrative impedance matching network that may be integrated within an antenna of the type shown in  FIG. 6  in accordance with some embodiments. 
         FIG. 10  is a top view showing how an illustrative antenna of the type shown in  FIG. 6  may have a first tuning state in which the antenna conveys antenna currents in a relatively high ultra-wideband communications band in accordance with some embodiments. 
         FIG. 11  is a top view showing how an illustrative antenna of the type shown in  FIG. 6  may have a second tuning state in which the antenna conveys antenna currents in a relatively low ultra-wideband communications band in accordance with some embodiments. 
         FIG. 12  is a plot of antenna performance (antenna efficiency) as a function of frequency for an illustrative antenna of the type shown in  FIGS. 6, 10, and 11  in accordance with some embodiments. 
         FIG. 13  is a circuit diagram of an illustrative tuning component having a switchable inductor that may be integrated within an antenna of the type shown in  FIGS. 6, 10, and 11  in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with wireless circuitry (sometimes referred to herein as wireless communications circuitry). The wireless circuitry may be used to support wireless communications in multiple wireless communications bands. Communications bands (sometimes referred to herein as frequency bands) handled by the wireless circuitry can include satellite navigation system communications bands, cellular telephone communications bands, wireless local area network communications bands, near-field communications bands, ultra-wideband communications bands, or other wireless communications bands. 
     The wireless circuitry may include one or more antennas. The antennas of the wireless circuitry can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, patch antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. 
     The conductive electronic device structures may include conductive housing structures. The conductive housing structures may include peripheral structures such as peripheral conductive structures that run around the periphery of the electronic device. The peripheral conductive structures may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. 
     Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for electronic device  10 . Antennas may also be formed using an antenna ground plane and/or an antenna resonating element formed from conductive housing structures (e.g., internal and/or external structures, support plate structures, etc.). 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a handheld device such as a cellular telephone, a media player, or other small portable device. Device  10  may also be a set-top box, a desktop computer, a display into which a computer or other processing circuitry has been integrated, a display without an integrated computer, a wireless access point, a wireless base station, an electronic device incorporated into a kiosk, building, or vehicle, or other suitable electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may be mounted on the front face of device  10 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. The rear face of housing  12  (i.e., the face of device  10  opposing the front face of device  10 ) may have a substantially planar housing wall such as rear housing wall  12 R (e.g., a planar housing wall). Rear housing wall  12 R may have slots that pass entirely through the rear housing wall and that therefore separate portions of housing  12  from each other. Rear housing wall  12 R may include conductive portions and/or dielectric portions. If desired, rear housing wall  12 R may include a planar metal layer covered by a thin layer or coating of dielectric such as glass, plastic, sapphire, or ceramic. Housing  12  may also have shallow grooves that do not pass entirely through housing  12 . The slots and grooves may be filled with plastic or other dielectric. If desired, portions of housing  12  that have been separated from each other (e.g., by a through slot) may be joined by internal conductive structures (e.g., sheet metal or other metal members that bridge the slot). 
     Housing  12  may include peripheral housing structures such as peripheral structures  12 W. Peripheral structures  12 W and conductive portions of rear housing wall  12 R may sometimes be referred to herein collectively as conductive structures of housing  12 . Peripheral structures  12 W may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, peripheral structures  12 W may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges and that extend from rear housing wall  12 R to the front face of device  10  (as an example). Peripheral structures  12 W or part of peripheral structures  12 W may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ) if desired. Peripheral structures  12 W may, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.). 
     Peripheral structures  12 W may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, peripheral conductive sidewalls, peripheral conductive sidewall structures, conductive housing sidewalls, peripheral conductive housing sidewalls, sidewalls, sidewall structures, or a peripheral conductive housing member (as examples). Peripheral conductive housing structures  12 W may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral conductive housing structures  12 W. 
     It is not necessary for peripheral conductive housing structures  12 W to have a uniform cross-section. For example, the top portion of peripheral conductive housing structures  12 W may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral conductive housing structures  12 W may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral conductive housing structures  12 W may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral conductive housing structures  12 W serve as a bezel for display  14 ), peripheral conductive housing structures  12 W may run around the lip of housing  12  (i.e., peripheral conductive housing structures  12 W may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     Rear housing wall  12 R may lie in a plane that is parallel to display  14 . In configurations for device  10  in which some or all of rear housing wall  12 R is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  12 W as integral portions of the housing structures forming rear housing wall  12 R. For example, rear housing wall  12 R of device  10  may include a planar metal structure and portions of peripheral conductive housing structures  12 W on the sides of housing  12  may be formed as flat or curved vertically extending integral metal portions of the planar metal structure (e.g., housing structures  12 R and  12 W may be formed from a continuous piece of metal in a unibody configuration). Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . Rear housing wall  12 R may have one or more, two or more, or three or more portions. Peripheral conductive housing structures  12 W and/or conductive portions of rear housing wall  12 R may form one or more exterior surfaces of device  10  (e.g., surfaces that are visible to a user of device  10 ) and/or may be implemented using internal structures that do not form exterior surfaces of device  10  (e.g., conductive housing structures that are not visible to a user of device  10  such as conductive structures that are covered with layers such as thin cosmetic layers, protective coatings, and/or other coating layers that may include dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of device  10  and/or serve to hide peripheral conductive housing structures  12 W and/or conductive portions of rear housing wall  12 R from view of the user). 
     Display  14  may have an array of pixels that form an active area AA that displays images for a user of device  10 . For example, active area AA may include an array of display pixels. The array of pixels may be formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels or other light-emitting diode pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. If desired, active area AA may include touch sensors such as touch sensor capacitive electrodes, force sensors, or other sensors for gathering a user input. 
     Display  14  may have an inactive border region that runs along one or more of the edges of active area AA. Inactive area IA may be free of pixels for displaying images and may overlap circuitry and other internal device structures in housing  12 . To block these structures from view by a user of device  10 , the underside of the display cover layer or other layers in display  14  that overlap inactive area IA may be coated with an opaque masking layer in inactive area IA. The opaque masking layer may have any suitable color. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, transparent ceramic, sapphire, or other transparent crystalline material, or other transparent layer(s). The display cover layer may have a planar shape, a convex curved profile, a shape with planar and curved portions, a layout that includes a planar main area surrounded on one or more edges with a portion that is bent out of the plane of the planar main area, or other suitable shapes. The display cover layer may cover the entire front face of device  10 . In another suitable arrangement, the display cover layer may cover substantially all of the front face of device  10  or only a portion of the front face of device  10 . Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button. An opening may also be formed in the display cover layer to accommodate ports such as speaker port  16  or a microphone port. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.) and/or audio ports for audio components such as a speaker and/or a microphone if desired. 
     Display  14  may include conductive structures such as an array of capacitive electrodes for a touch sensor, conductive lines for addressing pixels, driver circuits, etc. Housing  12  may include internal conductive structures such as metal frame members and a planar conductive housing member (sometimes referred to as a backplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more metal parts that is welded or otherwise connected between opposing sides of peripheral conductive structures  12 W). The backplate may form an exterior rear surface of device  10  or may be covered by layers such as thin cosmetic layers, protective coatings, and/or other coatings that may include dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of device  10  and/or serve to hide the backplate from view of the user. Device  10  may also include conductive structures such as printed circuit boards, components mounted on printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground plane in device  10 , may extend under active area AA of display  14 , for example. 
     In regions  22  and  20 , openings may be formed within the conductive structures of device  10  (e.g., between peripheral conductive housing structures  12 W and opposing conductive ground structures such as conductive portions of rear housing wall  12 R, conductive traces on a printed circuit board, conductive electrical components in display  14 , etc.). These openings, which may sometimes be referred to as gaps, may be filled with air, plastic, and/or other dielectrics and may be used in forming slot antenna resonating elements for one or more antennas in device  10 , if desired. 
     Conductive housing structures and other conductive structures in device  10  may serve as a ground plane for the antennas in device  10 . The openings in regions  22  and  20  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  22  and  20 . If desired, the ground plane that is under active area AA of display  14  and/or other metal structures in device  10  may have portions that extend into parts of the ends of device  10  (e.g., the ground may extend towards the dielectric-filled openings in regions  22  and  20 ), thereby narrowing the slots in regions  22  and  20 . 
     In general, device  10  may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device  10  may be located at opposing first and second ends of an elongated device housing (e.g., ends at regions  22  and  20  of device  10  of  FIG. 1 ), along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of these locations. The arrangement of  FIG. 1  is merely illustrative. 
     Portions of peripheral conductive housing structures  12 W may be provided with peripheral gap structures. For example, peripheral conductive housing structures  12 W may be provided with one or more gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral conductive housing structures  12 W may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide peripheral conductive housing structures  12 W into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral conductive housing structures  12 W (e.g., in an arrangement with two gaps  18 ), three peripheral conductive segments (e.g., in an arrangement with three gaps  18 ), four peripheral conductive segments (e.g., in an arrangement with four gaps  18 ), six peripheral conductive segments (e.g., in an arrangement with six gaps  18 ), etc. The segments of peripheral conductive housing structures  12 W that are formed in this way may form parts of antennas in device  10  if desired. 
     If desired, openings in housing  12  such as grooves that extend partway or completely through housing  12  may extend across the width of the rear wall of housing  12  and may penetrate through the rear wall of housing  12  to divide the rear wall into different portions. These grooves may also extend into peripheral conductive housing structures  12 W and may form antenna slots, gaps  18 , and other structures in device  10 . Polymer or other dielectric may fill these grooves and other housing openings. In some situations, housing openings that form antenna slots and other structure may be filled with a dielectric such as air. 
     In order to provide an end user of device  10  with as large of a display as possible (e.g., to maximize an area of the device used for displaying media, running applications, etc.), it may be desirable to increase the amount of area at the front face of device  10  that is covered by active area AA of display  14 . Increasing the size of active area AA may reduce the size of inactive area IA within device  10 . This may reduce the area behind display  14  that is available for antennas within device  10 . For example, active area AA of display  14  may include conductive structures that serve to block radio-frequency signals handled by antennas mounted behind active area AA from radiating through the front face of device  10 . It would therefore be desirable to be able to provide antennas that occupy a small amount of space within device  10  (e.g., to allow for as large of a display active area AA as possible) while still allowing the antennas to communicate with wireless equipment external to device  10  with satisfactory efficiency bandwidth. 
     In a typical scenario, device  10  may have one or more upper antennas and one or more lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device  10  in region  20 . A lower antenna may, for example, be formed at the lower end of device  10  in region  22 . Additional antennas may be formed along the edges of housing  12  extending between regions  20  and  22  if desired. The antennas may be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme. 
     Antennas in device  10  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, near-field communications, ultra-wideband communications, etc. 
     A schematic diagram of illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry  28 . Control circuitry  28  may include storage such as storage circuitry  24 . Storage circuitry  24  may include hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. 
     Control circuitry  28  may include processing circuitry such as processing circuitry  26 . Processing circuitry  26  may be used to control the operation of device  10 . Processing circuitry  26  may include on one or more microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), etc. Control circuitry  28  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  24  (e.g., storage circuitry  24  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  24  may be executed by processing circuitry  26 . 
     Control circuitry  28  may be used to run software on device  10  such as external node location applications, satellite navigation applications, internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), IEEE 802.15.4 ultra-wideband communications protocols or other ultra-wideband communications protocols, etc. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  30 . 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, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, vibrators or other haptic feedback engines, digital data port devices, light sensors (e.g., infrared light sensors, visible light sensors, etc.), light-emitting diodes, motion sensors (accelerometers), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), etc. 
     Input-output circuitry  30  may include wireless circuitry  34 . To support wireless communications, wireless 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 such as antennas  40 , transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     While control circuitry  28  is shown separately from wireless circuitry  34  in the example of  FIG. 2  for the sake of clarity, wireless circuitry  34  may include processing circuitry that forms a part of processing circuitry  26  and/or storage circuitry that forms a part of storage circuitry  24  of control circuitry  28  (e.g., portions of control circuitry  28  may be implemented on wireless circuitry  34 ). As an example, control circuitry  28  (e.g., processing circuitry  26 ) may include baseband processor circuitry or other control components that form a part of wireless circuitry  34 . 
     Wireless circuitry  34  may include radio-frequency transceiver circuitry for handling various radio-frequency communications bands. For example, wireless circuitry  34  may include wireless local area network (WLAN) and wireless personal area network (WPAN) transceiver circuitry  38 . Transceiver circuitry  38  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications or other WLAN bands and may handle the 2.4 GHz Bluetooth® communications band or other WPAN bands. Transceiver circuitry  38  may sometimes be referred to herein as WLAN/WPAN transceiver circuitry  38 . 
     Wireless circuitry  34  may use cellular telephone transceiver circuitry  42  for handling wireless communications in frequency ranges (communications bands) such as a cellular low band (LB) from 600 to 960 MHz, a cellular low-midband (LMB) from 1410 to 1510 MHz, a cellular midband (MB) from 1710 to 2170 MHz, a cellular high band (HB) from 2300 to 2700 MHz, a cellular ultra-high band (UHB) from 3300 to 5850 MHz, or other communications bands between 600 MHz and 5850 MHz or other suitable frequencies (as examples). Cellular telephone transceiver circuitry  42  may handle voice data and non-voice data. 
     Wireless circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry  36  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver circuitry  36  are received from a constellation of satellites orbiting the earth. Wireless circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless circuitry  34  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) transceiver circuitry (e.g., an NFC transceiver operating at 13.56 MHz or another suitable frequency), etc. 
     In NFC links, wireless signals are typically conveyed over a few inches at most. In satellite navigation system links, cellular telephone links, and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. In WLAN and WPAN links at 2.4 and 5 GHz and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. Antenna diversity schemes may be used if desired to ensure that the antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     Wireless circuitry  34  may include ultra-wideband (UWB) transceiver circuitry  44  that supports communications using the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols. Ultra-wideband radio-frequency signals may be based on an impulse radio signaling scheme that uses band-limited data pulses. Ultra-wideband radio-frequency signals may have any desired bandwidths such as bandwidths between 499 MHz and 1331 MHz, bandwidths greater than 500 MHz, etc. The presence of lower frequencies in the baseband may sometimes allow ultra-wideband radio-frequency signals to penetrate through objects such as walls. In an IEEE 802.15.4 system, a pair of electronic devices may exchange wireless time stamped messages. Time stamps in the messages may be analyzed to determine the time of flight of the messages and thereby determine the distance (range) between the devices and/or an angle between the devices (e.g., an angle of arrival of incoming radio-frequency signals). UWB transceiver circuitry  44  may operate (i.e., convey radio-frequency signals) in frequency bands such as an ultra-wideband communications band between about 5 GHz and about 8.3 GHz (e.g., a 6.5 GHz UWB communications band, an 8 GHz UWB communications band, and/or at other suitable frequencies). 
     As an example, device  10  may convey radio-frequency signals  46  at ultra-wideband frequencies with external wireless equipment  10 ′ to determine a distance between device  10  and external wireless equipment  10 ′ and/or to determine an angle of arrival of radio-frequency signals  46  (e.g., to determine the relative orientation and/or position of external wireless equipment  10 ′ with respect to device  10 ). External wireless equipment  10 ′ may be an electronic device like device  10  or may include any other desired wireless equipment. Radio-frequency signals conveyed by device  10  in an ultra-wideband communications band and using an ultra-wideband communications protocol (e.g., radio-frequency signals  46 ) may sometimes be referred to herein as ultra-wideband signals. Radio-frequency signals conveyed by device  10  in other communications bands (e.g., using communications protocols other than an ultra-wideband communications protocol) may sometimes be referred to here as non-ultra-wideband (non-UWB) signals. Non-UWB signals conveyed by device  10  may include, for example, radio-frequency signals in a cellular telephone communications band, a WLAN communications band, etc. 
     Wireless circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable types of antenna structures. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, dipole antenna structures, monopole antenna structures, hybrids of two or more of these designs, etc. If desired, one or more of antennas  40  may be cavity-backed antennas. 
     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. Dedicated antennas may be used for conveying radio-frequency signals in a UWB communications band (e.g., UWB signals) or, if desired, antennas  40  can be configured to convey both radio-frequency signals in a UWB communications band and radio-frequency signals in non-UWB communications bands (e.g., wireless local area network signals and/or cellular telephone signals). Antennas  40  can include two or more antennas for handling ultra-wideband wireless communication. In one suitable arrangement that is described herein as an example, antennas  40  include one or more groups of three antennas (sometimes referred to herein as triplets of antennas) for handling ultra-wideband wireless communication. In yet another suitable arrangement, antennas  40  may include a triplet of sets of antennas, where each set of antenna includes four antennas that are tuned to four respective frequencies (e.g., antennas  40  may include three sets of four antennas for handling ultra-wideband wireless communication). Antennas  40  may include one or more doublets of antennas for handling ultra-wideband wireless communication if desired. 
     Space is often at a premium in electronic devices such as device  10 . In order to minimize space consumption within device  10 , the same antenna  40  may be used to cover multiple communications bands. In one suitable arrangement that is described herein as an example, each antenna  40  that is used to perform ultra-wideband wireless communication may be a multi-band antenna that conveys radio-frequency signals in at least two ultra-wideband communications bands (e.g., the 6.5 GHz UWB communications band and the 8.0 GHz UWB communications band). If desired, the same antenna  40  may cover both the 6.5 GHz UWB communications band, the 8.0 GHz UWB communications band, one or more cellular ultra-high bands, and a 5.0 GHz WLAN communications band. 
     As shown in  FIG. 3 , wireless circuitry  34  may include transceiver circuitry  60  (e.g., GPS receiver circuitry  36 , WLAN/WPAN circuitry  38 , cellular telephone transceiver circuitry  42 , and/or UWB transceiver circuitry  44  of  FIG. 2 ). Transceiver circuitry  60  may be coupled to antenna structures such as a given antenna  40  using a radio-frequency transmission line path such as radio-frequency transmission line path  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  40  with the ability to cover communications frequencies of interest, antenna  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna  40  may be provided with adjustable circuits such as tunable components  64  to tune the antenna over communications (frequency) bands of interest. Tunable components  64  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  64  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 control paths such as control path  62  that adjust inductance values, capacitance values, or other parameters associated with tunable components  64 , thereby tuning antenna  40  to cover desired communications bands. Antenna tuning components that are used to adjust the frequency response of antenna  40  such as tunable components  64  may sometimes be referred to herein as antenna tuning components, tuning components, antenna tuning elements, tuning elements, adjustable tuning components, adjustable tuning elements, or adjustable components. 
     Radio-frequency transmission line path  50  may include one or more radio-frequency transmission lines. Radio-frequency transmission lines in radio-frequency transmission line path  50  may, for example, include coaxial cable transmission lines, stripline transmission lines, microstrip transmission lines, coaxial probes realized by a metalized vias, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide structures (e.g., coplanar waveguides or grounded coplanar waveguides), combinations of these types of radio-frequency transmission lines and/or other transmission line structures, etc. 
     Radio-frequency transmission line path  50  may have a positive signal conductor such as signal conductor  52  and a ground signal conductor such as ground conductor  54 . The radio-frequency transmission lines in radio-frequency transmission line path  50  may, for example, be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, radio-frequency transmission lines in radio-frequency transmission line path  50  may also include transmission line conductors (e.g., signal conductors  52  and ground conductors  54 ) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive). The multilayer laminated structures may, if desired, be folded or bent in multiple dimensions (e.g., two or three dimensions) and may maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). 
     A matching network (e.g., an adjustable matching network formed using tunable components  64 ) may include components such as inductors, resistors, and capacitors used in matching the impedance of antenna  40  to the impedance of radio-frequency transmission line path  50 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna  40  and may be tunable and/or fixed components. 
     Radio-frequency transmission line path  50  may be coupled to antenna feed structures associated with antenna  40 . As an example, antenna  40  may form an inverted-F antenna, a slot antenna, a monopole antenna, a dipole antenna, or other antenna having an antenna feed  48  with a positive antenna feed terminal such as positive antenna feed terminal  56  and a ground antenna feed terminal such as ground antenna feed terminal  58 . Signal conductor  52  may be coupled to positive antenna feed terminal  56  and ground conductor  54  may be coupled to ground antenna feed terminal  58 . Other types of antenna feed arrangements may be used if desired. For example, antenna  40  may be fed using multiple feeds each coupled to a respective port of radio-frequency transceiver circuitry  60  over a corresponding radio-frequency transmission line path. If desired, signal conductor  52  may be coupled to multiple locations on antenna  40  (e.g., antenna  40  may include multiple positive antenna feed terminals coupled to signal conductor  52  of the same radio-frequency transmission line path  50 ). Switches may be interposed on the signal conductor between radio-frequency transceiver circuitry  60  and the positive antenna feed terminals if desired (e.g., to selectively activate one or more positive antenna feed terminals at any given time). The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Control circuitry  28  may use information from a proximity sensor, wireless performance metric data such as received signal strength information, device orientation information from an orientation sensor, device motion data from an accelerometer or other motion detecting sensor, information about a usage scenario of device  10 , information about whether audio is being played through speaker port  16  ( FIG. 1 ), information from one or more antenna impedance sensors, information on desired frequency bands to use for communications, and/or other information in determining when antenna  40  is being affected by the presence of nearby external objects or is otherwise in need of tuning. In response, control circuitry  28  may adjust an adjustable inductor, adjustable capacitor, switch, or other tunable components such as tunable components  64  to ensure that antenna  40  operates as desired. Adjustments to tunable components  64  may also be made to extend the frequency coverage of antenna  40  (e.g., to cover desired communications bands that extend over a range of frequencies larger than antenna  40  would cover without tuning). 
     Antenna  40  may include antenna resonating element structures (sometimes referred to herein as radiating element structures), antenna ground plane structures (sometimes referred to herein as ground plane structures, ground structures, or antenna ground structures), an antenna feed such as antenna feed  48 , and other components (e.g., tunable components  64 ). Antenna  40  may be configured to form any suitable type of antenna. 
       FIG. 4  is a schematic diagram of antenna structures that may be used in forming antenna  40 . As shown in  FIG. 4 , antenna  40  may include an antenna resonating element such as antenna resonating element  68  (e.g., an inverted-F antenna resonating element) and an antenna ground (sometimes referred to herein as a ground plane) such as antenna ground  66 . Antenna resonating element  68  may have a main resonating element arm such as arm  70 . The length of arm  70  may be selected so that antenna  40  resonates at desired operating frequencies (e.g., where the length of arm  70  is approximately equal to one-quarter of the effective wavelength corresponding to a frequency in a communications band handled by antenna  40 ). Antenna resonating element  68  may also exhibit resonances at harmonic frequencies. 
     If desired, other conductive structures in the vicinity of arm  70  may contribute to the radiative response of antenna  40  (e.g., antenna resonating element  68  may include conductive structures that are separate from arm  70  such as conductive portions of other antennas in the vicinity of antenna  40 ). Arm  70  may be separated from antenna ground  66  by a dielectric-filled opening or gap. Antenna ground  66  may be formed from housing structures such as a conductive support plate, conductive portions of display  14  ( FIG. 1 ), conductive traces on a printed circuit board, metal portions of electronic components, or other conductive ground structures. 
     If desired, arm  70  may be coupled to antenna ground  66  by one or more return paths such as return path  73 . Positive antenna feed terminal  56  of antenna feed  48  may be coupled to arm  70 . Ground antenna feed terminal  58  may be coupled to antenna ground  66  (e.g., antenna feed  48  may run parallel to return path  73 ). If desired, antenna resonating element  68  may include more than one resonating arm to support radiation in multiple communications bands (e.g., antenna resonating element  68  may include one or more arms in addition to arm  70 ). Each arm may help to support radiation in one or more respective communications bands, for example. In one suitable arrangement that is sometimes described herein as an example, antenna resonating element  68  may include two arms extending from opposing sides of antenna feed  48  and/or return path  73 . Antenna resonating element  68  may include one or more parasitic antenna resonating elements if desired. Arm  70  may have other shapes and may follow any desired path (e.g., paths having curved and/or straight segments). 
     If desired, antenna resonating element  68  may include one or more tunable components that are coupled between arm  70  and antenna ground  66 . As shown in  FIG. 4 , for example, a tunable component such as tunable component  72  (e.g., a tunable component such as tunable component  64  of  FIG. 3 ) may be coupled between arm  70  and antenna ground  66 . Tunable component  72  may exhibit a capacitance, resistance, and/or inductance that is adjusted in response to control signals  74  provided to tunable component  72  from control circuitry  28  ( FIG. 3 ). 
     A top interior view of an illustrative portion of device  10  that contains multiple antennas  40  is shown in  FIG. 5  (e.g., at the top-left corner of device  10  within region  20  of  FIG. 1 ). As shown in  FIG. 5 , device  10  may have peripheral conductive housing structures such as peripheral conductive housing structures  12 W. Peripheral conductive housing structures  12 W may be divided by dielectric-filled peripheral gaps  18  (e.g., plastic gaps) such as gaps  18 - 1  and  18 - 2 . Gap  18 - 1  may divide peripheral conductive housing structures  12 W into a first segment  88  and a second segment  76 . Gap  18 - 2  may separate second segment  76  from a third segment  80  of peripheral conductive housing structures  12 W. 
     As shown in  FIG. 5 , device  10  may include at least two antennas  40  such as a first antenna  40 - 1  and a second antenna  40 - 2 . Antenna  40 - 2  may have an antenna resonating element arm (e.g., arm  70  of  FIG. 4 ) formed from segment  76  of peripheral conductive housing structures  12 W. Ground structures  94  may form the antenna ground (e.g., antenna ground  66  of  FIG. 4 ) for antenna  40 - 2 . Antenna  40 - 2  may have an antenna feed  48 - 2  with a positive antenna feed terminal  56 - 2  coupled to segment  76  and a ground antenna feed terminal  58 - 2  coupled to ground structures  94 . 
     Segments  76  and  80  of peripheral conductive housing structures  12 W may be separated from ground structures  94  by dielectric-filled slot  82 . Air, plastic, ceramic, glass, and/or other dielectric materials may fill slot  82 . In one suitable arrangement, slot  82  may be continuous with gaps  18 - 1  and  18 - 2  and a single piece of dielectric material (e.g., plastic) may fill slot  82 , gap  18 - 1 , and gap  18 - 2 . The length of segment  76  may be selected to provide antenna  40 - 2  with a response peak in one or more communications bands. The length of segment  76  from antenna feed  48 - 2  to tip (end)  78  of segment  76  and/or the length of segment  76  from antenna feed  48 - 2  to dielectric gap  18 - 2  may, for example, be approximately equal to one-quarter of an effective wavelength of operation of antenna  40 - 2  (e.g., where the effective wavelength is equal to the free space wavelength modified by a constant value determined by the dielectric material in slot  82 ). 
     Segment  76  may also have one or more harmonic modes that cover additional frequencies. Antenna  40 - 2  may also include a tunable component  72 - 2  (e.g., a tunable component such as tunable component  64  of  FIG. 3 ) that is coupled between segment  76  and ground structures  94 . Tunable component  72 - 2  may also form a return path for antenna  40 - 2  (e.g., return path  73  of  FIG. 4 ) if desired (e.g., depending on the state of the tunable component). Tunable component  72 - 2  may be adjusted to tune the frequency response of antenna  40 - 2 . Slot  82  may, if desired, be a radiating slot having a perimeter that is selected to contribute to the radiative response of antenna  40 - 2  (e.g., antenna  40 - 2  may be a hybrid-inverted-F-slot antenna). 
     Ground structures  94  may have an upper edge  84  that is separated from segment  76  by slot  82 . If desired, slot  82  may include an extended portion  86  that extends downwards beyond upper edge  84  (e.g., parallel to the Y-axis) and towards the bottom end of device  10 . Extended portion  86  of slot  82  may extend beyond gap  18 - 1  or the bottom edge of extended portion  86  may be parallel with the bottom edge of gap  18 - 1 . This example is merely illustrative and, in general, slot  82  and ground structures  94  may have any desired shapes (e.g., upper edge  84  of ground structures  94  may follow any desired straight and/or curved path). 
     Antenna  40 - 1  may have an antenna resonating element  68 - 1  that overlaps slot  82  (e.g., extended portion  86  of slot  82 ). Antenna resonating element  68 - 1  may include one or more arms (e.g., arm  70  of  FIG. 4 ). Antenna  40 - 1  may be fed using antenna feed  48 - 1  coupled between antenna resonating element  68 - 1  and ground structures  94  (e.g., antenna feed  48 - 1  may include positive antenna feed terminal  56 - 1  coupled to antenna resonating element  68 - 1  and ground antenna feed terminal  58 - 1  coupled to ground structures  94 ). Ground structures  94  may form part of the antenna ground for antenna  40 - 1  (e.g., antenna ground  66  of  FIG. 4 ). Antenna  40 - 1  may include one or more tunable components such as tunable component  72 - 1  (e.g., a tunable component such as tunable component  64  of  FIG. 3 ) coupled between antenna resonating element  68 - 1  and ground structures  94 . If desired, antenna currents induced on the return path for antenna  40 - 2  (e.g., on tunable component  72 - 2 ) and/or on segment  76  (e.g., at or adjacent to tip  78 ) may also contribute to the radiative response of antenna  40 - 1  (e.g., segment  76  and/or tunable component  72 - 2  may form part of antenna  40 - 1 ). 
     Ground structures  94  may be formed from conductive housing structures, from electrical device components in device  10 , from printed circuit board traces, from strips of conductor such as strips of wire and metal foil, from conductive portions of display  14  ( FIG. 1 ), and/or other conductive structures. In one suitable arrangement, ground structures  94  may include conductive portions of housing  12  (e.g., portions of rear housing wall  12 R of  FIG. 1  and/or portions of a different conductive support plate in device  10 ) and conductive portions of display  14  ( FIG. 1 ). Segment  88  of peripheral conductive housing structures  12 W may be coupled to ground structures  94  and may therefore form part of the antenna ground for antenna  40 - 1  and/or antenna  40 - 2 . Segment  88  and ground structures  94  may be formed from a single integral piece of metal if desired. 
     Device  10  may include additional antennas such as antennas  40 - 3 ,  40 - 4 , and  40 - 5  that are aligned with respective openings in ground structures  94 . Antennas  40 - 3 ,  40 - 4 , and  40 - 5  may, for example, be used to transmit and receive UWB signals through the rear face of device  10  (e.g., through rear housing wall  12 R of  FIG. 1 ). Antennas  40 - 3 ,  40 - 4 , and  40 - 5  may, for example, form a triplet of antennas that can receive UWB signals that are processed by control circuitry  28  ( FIG. 2 ) to determine a three-dimensional angle-of-arrival of the received UWB signals. 
     In one suitable arrangement that is sometimes described herein as an example, antennas  40 - 1 ,  40 - 3 ,  40 - 4 , and  40 - 5  are each mounted to the same dielectric substrate (e.g., to the same rigid or flexible printed circuit board). For example, antenna resonating element  68 - 1  may be formed from conductive traces patterned on the dielectric substrate. The dielectric substrate may press antennas  40 - 3 ,  40 - 4 , and  40 - 5  against the rear housing wall of device  10  (e.g., rear housing wall  12 R of  FIG. 1 ). If desired, the dielectric substrate may press antenna  40 - 1  against slot  82  and/or the rear housing wall of device  10 . The radio-frequency transmission line paths used to feed antennas  40 - 1 ,  40 - 3 ,  40 - 4 , and  40 - 5  may be formed from conductive traces (e.g., conductive traces that form stripline transmission lines or other radio-frequency transmission lines) on the dielectric substrate, for example. 
     Conductive structures over antennas  40 - 3 ,  40 - 4 , and  40 - 5  (e.g., display  14  of  FIG. 1 , a battery for device  10 , etc.) may effectively block antennas  40 - 3 ,  40 - 4 , and  40 - 5  from transmitting or receiving UWB signals through the front face of device  10  (e.g., in the +Z direction). In order to help provide UWB coverage through the front face of device  10  (e.g., to provide a full sphere of UWB coverage around all sides of device  10 ), antenna  40 - 1  may also be used to transmit and/or receive UWB signals. Because antenna  40 - 1  is located at the corner of device  10 , antenna  40 - 1  may be at least partially aligned with the inactive area of the display at the front face of device  10  (e.g., inactive area IA of display  14  of  FIG. 1 ). This may allow antenna  40 - 1  to transmit and/or receive UWB signals through the front face of device  10  without the signals being blocked by conductive structures in display  14  (e.g., pixel circuitry or other components associated with active area AA of  FIG. 1 ). Antenna currents induced on peripheral conductive housing structures  12 W by antenna resonating element  68 - 1  may also help to ensure that antenna  40 - 1  can convey UWB signals through the front face of device  10 . Antenna  40 - 1  may also convey UWB signals through the rear face of device  10  (e.g., through slot  82  in the −Z direction) and laterally through gap  18 - 1  in peripheral conductive housing structures  12 W. 
     Antenna  40 - 1  may be used to transmit UWB signals for use by external communications equipment (e.g., external communications equipment  10 ′ of  FIG. 2 ) in determining an angle of arrival of the transmitted UWB signals and/or a distance between the external communications equipment and device  10 . If desired, antenna  40 - 1  may also be used to receive UWB signals from external communications equipment (e.g., external communications equipment  10 ′ of  FIG. 2 ) for use in determining the distance between the external communications equipment and device  10 . 
     Antenna  40 - 1  may convey UWB signals in multiple UWB communications bands. For example, antenna  40 - 1  may convey UWB signals in a first UWB communications band between about 6250 MHz and 6750 MHz (e.g., UWB Channel  5 ) and a second UWB communications band between about 7350 MHz and 8250 MHz (e.g., UWB Channel  9 ). If desired, tunable component  72 - 1  may be adjusted between a first state (sometimes referred to herein as a tuning state or operating state) in which antenna  40 - 1  covers the second UWB communications band and a second state in which antenna  40 - 1  covers the first UWB communications band. 
     If desired, antenna  40 - 1  may also be used to convey non-UWB signals in one or more other communications bands in addition to conveying UWB signals. In one suitable arrangement that is sometimes described herein as an example, antenna  40 - 1  may convey non-UWB signals in first and second communications bands such as a 5.0 GHz WLAN communications band (e.g., a frequency band from about 5180 MHz to about 5850 MHz) and one or more cellular ultra-high bands at frequencies between about 3400 MHz and 3700 MHz. Examples of cellular ultra-high bands that may be covered by antenna  40 - 1  include Long Term Evolution (LTE) band B 42  (e.g., between about 3.4 GHz and 3.6 GHz) and LTE band B 48  (e.g., between about 3.6 GHz and 3.7 GHz). 
     As shown in  FIG. 5 , radio-frequency transmission line path  50 - 1  may couple antenna feed  48 - 1  on antenna  40 - 1  to WLAN/WPAN transceiver circuitry  38 , cellular telephone transceiver circuitry  42 , and UWB transceiver circuitry  44 . Impedance matching circuitry such as impedance matching network (MN)  90  may be interposed on radio-frequency transmission line path  50 - 1  for matching the impedance of radio-frequency transmission line path  50 - 1  to the impedance of antenna resonating element  68 - 1  and/or for tuning the frequency response of antenna  40 - 1 . 
     WLAN/WPAN transceiver circuitry  38  may convey (non-UWB) radio-frequency signals in a WLAN or WPAN communications band such as the 5.0 GHz WLAN band over antenna feed  48 - 1 . Cellular telephone transceiver circuitry  42  may convey (non-UWB) radio-frequency signals in one or more cellular telephone communications bands such as one or more ultra-high bands over antenna feed  48 - 1 . UWB transceiver circuitry  44  may convey UWB signals in one or more UWB communications bands over antenna feed  48 - 1 . Antenna  40 - 1  may concurrently convey one or more (e.g., all) of these signals at any given time with satisfactory antenna efficiency. 
     Filter circuitry such as filter circuitry  92  may be interposed on radio-frequency transmission line path  50 - 1  to help isolate the signals conveyed by transceiver circuitry  38 ,  42 , and  44  (e.g., to prevent UWB signals from passing to transceiver circuitry  38  and  42 , to prevent non-UWB signals from passing to UWB transceiver circuitry  44 , to prevent non-UWB signals in a WLAN communications band from passing to cellular telephone transceiver circuitry  42 , etc.). Filter circuitry  92  may include passive filter circuitry such as a duplexer, diplexer, triplexer, low pass filter, band pass filter, band stop filter, high pass filter, and/or other filter circuitry that helps to isolate the signals conveyed by transceiver circuitry  38 ,  42 , and  44 . If desired, filter circuitry  92  may also include active circuitry such as switching circuitry that selectively couples one or more of transceiver circuitry  38 ,  42 , and  44  to antenna feed  48 - 1  at any given time. 
     As shown in  FIG. 5 , UWB transceiver circuitry  44  may be coupled to antenna  40 - 3  via radio-frequency transmission line path  50 - 3 , may be coupled to antenna  40 - 4  via radio-frequency transmission line path  50 - 4 , and may be coupled to antenna  40 - 5  via radio-frequency transmission line path  50 - 5 . Cellular telephone transceiver circuitry  42  may be coupled antenna feed  48 - 2  of antenna  40 - 2  via radio-frequency transmission line path  50 - 6 . If desired, WLAN/WPAN transceiver circuitry  38  may be coupled to antenna feed  48 - 2  via radio-frequency transmission line path  50 - 7  (e.g., in scenarios where antenna  40 - 2  also conveys radio-frequency signals in one or more WLAN or WPAN communications bands). GPS receiver circuitry such as GPS receiver circuitry  36  of  FIG. 2  may also be couple to antenna feed  48 - 2  if desired (e.g., in scenarios where antenna  40 - 2  also receives radio-frequency signals in a satellite navigation communications band). Transceiver circuitry  38 ,  42 , and  44  may each be mounted to the same substrate (e.g., a main logic board for device  10  that is separate from the dielectric substrate used to support antennas  40 - 1 ,  40 - 3 ,  40 - 4 , and  40 - 5 ). 
       FIG. 6  is a top view showing how antenna  40 - 1  may be used to convey non-UWB signals in a WLAN communications band and one or more cellular telephone communications bands. As shown in  FIG. 6 , antenna resonating element  68 - 1  of antenna  40 - 1  may include a first arm  100  and a second arm  102  (e.g., arms such as arm  70  of  FIG. 4 ) extending from opposing sides of antenna feed  48 - 1 . Locating first arm  100  and/or second arm  102  at or adjacent to (e.g., at least partially aligned with) gap  18 - 1  may allow antenna  40 - 1  to radiate in a lateral direction through gap  18 - 1  (e.g., to provide antenna  40 - 1  with a close to omnidirectional radiation pattern). 
     First arm  100  may have a first segment (portion)  110  extending from positive antenna feed terminal  56 - 1 , a second segment  106 , and a third segment  108 . Second segment  106  may have a first end that extends at a non-parallel angle (e.g., a perpendicular angle) from the end of first segment  110 . Third segment  108  may extend at a non-parallel angle (e.g., a perpendicular angle) from the second end of second segment  106 . Third segment  108  may, for example, extend parallel to first segment  110 . In this way, first arm  100  may laterally extend (wrap) around vertical axis  96  (e.g., an axis extending through extended portion  86  of slot  82  parallel to the Z-axis). 
     First arm  100  may be coupled to ground structures  94  by return path  104  (e.g., a return path such as return path  73  of  FIG. 4 ). Return path  104  may, for example, extend from first segment  110  and may be coupled to ground structures  94  at ground terminal  98 . First arm  100 , second arm  102 , and return path  104  may, for example, be formed from conductive traces patterned on a dielectric substrate or from any other desired conductive material on any other desired substrate (e.g., metal foil, conductive housing portions, etc.). Second arm  102  may laterally extend (wrap) around vertical axis  96  and third segment  108  of first arm  100 . First arm  100  may be shorter than second arm  102  and may thereby support a fundamental mode resonance at higher frequencies than second arm  102 . First arm  100  may therefore sometimes be referred to herein as high band arm  100  whereas second arm  102  is sometimes referred to herein as low band arm  102 . 
     As shown in  FIG. 6 , low band arm  102  may include a first segment (portion)  111  extending from positive antenna feed terminal  56 - 1  and the end of first segment  110  of high band arm  100 . Low band arm  102  may include a second segment  112  having a first end extending at a non-parallel angle (e.g., a perpendicular angle) from the end of first segment  111 . Second segment  112  of low band arm  102  may, for example, extend parallel to second segment  106  of high band arm  100 . Low band arm  102  may also include a third segment  114  extending at a non-parallel angle (e.g., a perpendicular angle) from the second end of second segment  112 . Third segment  114  of low band arm  102  may, for example, extend parallel to first segment  110  of high band arm  100  and first segment  111  of low band arm  102 . Second segment  112  of low band arm  102  may be separated from end  140  of high band arm  100  by gap  142 . Third segment  114  of low band arm  102  may be separated from third segment  108  of high band arm  100  by gap  138 . Third segment  114  of low band arm  102  may overlap some or all of the longitudinal length of third segment  108  of high band arm  100  (e.g., parallel to the X-axis). 
     The length of high band arm  100  may be selected to support a resonance in a WLAN communications band such as a 5.0 GHz WLAN communications band (e.g., in a fundamental mode of high band arm  100 ). Antenna feed  48 - 1  may convey radio-frequency signals in the WLAN communications band for WLAN/WPAN transceiver circuitry  38  ( FIG. 5 ). Corresponding antenna currents I 1  (e.g., antenna currents in the WLAN communications band) may flow on high band arm  100  (e.g., between positive antenna feed terminal  56 - 1  and end  140 ), as shown by arrow  128 . Antenna currents I 1  on high band arm  100  may radiate the radio-frequency signals in the WLAN communications band. The current density of antenna currents I 1  may be relatively high along the entire length of high band arm  100 , for example. 
     The length of low band arm  102  may be selected to support a resonance in one or more cellular telephone communications bands such as one or more ultra-high bands between 3400 MHz and 3700 MHz (e.g., in a fundamental mode of low band arm  102 ). Antenna feed  48 - 1  may convey radio-frequency signals in the cellular telephone communications band(s) for cellular telephone transceiver circuitry  42  ( FIG. 5 ). Corresponding antenna currents I 2  (e.g., antenna currents in the cellular telephone communications band(s)) may flow on low band arm  102 , a portion of high band arm  100  such as first segment  110 , return path  104 , and a portion of ground structures  94  (e.g., between ground antenna feed terminal  58 - 1  and end  116  of low band arm  102 ), as shown by arrow  126 . Antenna currents I 2  may radiate the radio-frequency signals in the cellular telephone communications band(s). Antenna currents I 2  may, for example, exhibit a higher current density between ground antenna feed terminal  58 - 1  and positive antenna feed terminal  56 - 1  (e.g., on return path  104  and first segment  110  of high band arm  100 ) than between positive antenna feed terminal  56 - 1  and end  116  of low band arm  102 . 
     Antenna currents I 2  may also be induced at tip  78  of segment  76 , as shown by arrow  130 , and on ground structures  94 , as shown by arrows  132 . Antenna currents I 2  on segment  76  and ground structures  94  may contribute to the radiative response of antenna  40 - 1  in the cellular telephone communication band(s) but may exhibit lower current density than the antenna currents I 2  flowing between positive antenna feed terminal  56 - 1  and ground antenna feed terminal  58 - 1 , for example. If desired, tunable component  72 - 1  may include inductive components that allow low band arm  102  to be implemented using a shorter length of conductor while still supporting a fundamental mode resonance in the cellular telephone communications band(s) than would otherwise be possible in the absence of tunable component  72 - 1  (e.g., the length of arrow  126  may be less than one-quarter of the effective wavelength of operation). Matching network  90  on radio-frequency transmission line path  50 - 1  may also be used to tune the frequency response of antenna  40 - 1 . 
     In this way, antenna  40 - 1  may concurrently cover both the WLAN communications band and the cellular telephone communications band(s) with satisfactory antenna efficiency. The example of  FIG. 6  is merely illustrative. In general, low band arm  102  and high band arm  100  may have other shapes (e.g., shapes following any curved and/or straight paths and having any desired number of curved and/or straight edges). In another suitable arrangement, tunable component  72 - 1  may be coupled between second segment  112  of low band arm  102  and ground structures  94  (e.g., at location  136 ). In yet another suitable arrangement, tunable component  72 - 1  may be coupled between third segment  114  of low band arm  102  and tunable component  72 - 2  of antenna  40 - 2  (e.g., tunable component  72 - 1  may be formed at location  134 ). As shown in  FIG. 6 , tunable component  72 - 2  may have a first terminal  118  coupled to segment  76  of peripheral conductive housing structures  12 W and a second (ground) terminal  120  coupled to ground structures  94 . In scenarios where tunable component  72 - 1  is formed at location  134 , terminal  124  of tunable component  72 - 1  may be coupled to any desired location on tunable component  72 - 2  between terminals  118  and  12  (e.g., terminal  124  of tunable component  72 - 1  may be coupled to the return path for antenna  40 - 2 ). 
     If desired, terminal  118  of tunable component  72 - 2  may include a conductive trace on an underlying dielectric substrate (e.g., a flexible printed circuit such as a flexible printed circuit that supports antenna  40 - 1 ) and/or may include other conductive interconnect structures that couple tunable component  72 - 2  to peripheral conductive housing structures  12 W (e.g., a conductive screw, conductive bracket, conductive clip, conductive pin, conductive spring, solder, solder, welds, conductive adhesive, a screw boss, etc.). If desired, ground structures  94  may include multiple conductive structures such as one or more conductive layers within device  10 . For example, ground structures  94  may include a first conductive layer formed from a portion of housing  12  (e.g., a conductive backplate that forms part of rear housing wall  12 R of  FIG. 1 ) and a second conductive layer formed from a conductive display frame or support plate associated with display  14  ( FIG. 1 ). In these scenarios, conductive interconnect structures (e.g., a conductive screw, conductive bracket, conductive clip, conductive pin, conductive spring, solder, solder, welds, conductive adhesive, a conductive screw boss, etc.) may electrically connect terminals  98 ,  58 - 1 ,  124 , and/or  120  to both the conductive display layer and the conductive housing layer. This may allow ground structures  94  to extend across both conductive portions of housing  12  and display  14  ( FIG. 1 ) so that the conductive material closest to antennas  40 - 1  and  40 - 2  are held at a ground potential. This may, for example, serve to maximize the antenna efficiency of antenna  40 - 1  and/or antenna  40 - 2  within the communications bands that are covered by antennas  40 - 1  and  40 - 2 . 
     Antenna  40 - 1  may also convey UWB signals in one or more UWB communications bands such as a first UWB communications band at 6.5 GHz and a second UWB communications band at 8.0 GHz.  FIG. 7  is a circuit diagram of tunable component  72 - 1  in one suitable arrangement. As shown in  FIG. 7 , tunable component  72 - 1  may include a first capacitor C 1 , a second capacitor C 2 , and an inductor L coupled in parallel between terminals  122  and  124 . In the example of  FIG. 7 , switch  144  is coupled in series between capacitor C 1  and terminal  124  and switch  146  is coupled in series between capacitor C 2  and terminal  124 . Switches  144  and/or  146  may be toggled on or off (e.g., by control circuitry  28  of  FIG. 3 ) to place antenna  40 - 1  in a selected one of at least first and second tuning states. In the first tuning state, one or both of switches  144  and  146  may be open (e.g., in an OFF state) and antenna  40 - 1  may convey UWB signals in the second UWB communications band at 8.0 GHz. In the second tuning state, one or both of switches  144  and  146  may be closed (e.g., in an ON state) and antenna  40 - 1  may convey UWB signals in the first UWB communications band at 6.5 GHz. 
       FIG. 8  is a circuit diagram of tunable component  72 - 1  in another suitable arrangement. As shown in  FIG. 8 , only first capacitor C 1  is switchable whereas second capacitor C 2  is fixed. In this example, switch  144  may be toggled on or off (e.g., by control circuitry  28  of  FIG. 3 ) to place antenna  40 - 1  in a selected one of at least the first and second tuning states. For example, in the second tuning state, switch  144  may be closed (e.g., in an ON state) and antenna  40 - 1  may convey UWB signals in the first UWB communications band at 6.5 GHz. In the first tuning state, switch  144  may be open (e.g., in an OFF state) and antenna  40 - 1  may convey UWB signals in the second UWB communications band at 8.0 GHz. As an example, capacitors C 1  and C 2  may each have a capacitance between 0.1 and 0.2 pF or other capacitances (e.g., capacitors C 1  and C 2  need not have the same capacitance). Inductor L may have an inductance between 5 and 10 nH, for example. 
     The example of  FIGS. 7 and 8  are merely illustrative. Capacitor C 2  may be omitted if desired. In general, tunable component  72 - 1  may include any desired switching circuitry and any desired number of fixed and/or adjustable capacitors, inductors, and/or resistors coupled in any desired manner between terminals  122  and  124 . 
       FIG. 9  is a circuit diagram of impedance matching network  90  of  FIG. 6  in one suitable arrangement. As shown in  FIG. 9 , impedance matching network  90  may include a capacitor C 3  coupled between antenna resonating element  68 - 1  of antenna  40 - 1  and ground structures  94 . Impedance matching network  90  may also include an inductor L 0  coupled between antenna resonating element  68 - 1  of antenna  40 - 1  and ground structures  94 . Antenna feed  48 - 1  may be interposed between capacitor C 3  and inductor L 0 . As an example, capacitor C 3  may have a capacitance between 0.2 and 0.5 pF. Inductor L 0  may, for example, have an inductance between 3 and 7 nH. This is merely illustrative. If desired, inductor L 0  may be interposed between antenna feed  48 - 1  and capacitor C 3  or capacitor C 3  may be interposed between antenna feed  48 - 1  and inductor L 0 . Impedance matching network  90  may include any desired number of capacitors, inductors, and/or resistors coupled in any desired manner between antenna resonating element  68 - 1  and ground structures  94 . Impedance matching network  90  may include switching circuitry if desired (e.g., to provide impedance matching network  90  with an adjustable impedance). 
       FIG. 10  is a top view showing how antenna  40 - 1  may be used to convey radio-frequency signals (UWB signals) in the second UWB communications band at 8.0 GHz (e.g., when tunable component  72 - 1  of  FIGS. 7 and 8  and thus antenna  40 - 1  are in the first tuning state). As shown in  FIG. 10 , low band arm  102  may exhibit a harmonic mode resonance in the second UWB communications band at 8.0 GHz (e.g., while the fundamental mode of low band arm  102  concurrently covers one or more cellular telephone communications bands as shown by current I 2  of  FIG. 6 ). 
     Antenna feed  48 - 1  may convey radio-frequency signals in the second UWB communications band for UWB transceiver circuitry  44  ( FIG. 5 ). Corresponding antenna currents I 3  (e.g., antenna currents in the second UWB communications band at 8.0 GHz) may flow on low band arm  102 , a portion of high band arm  100  such as first segment  110 , return path  104 , and a portion of ground structures  94  (e.g., between terminal  124  of tunable component  72 - 1  and end  116  of low band arm  102 ), as shown by arrows  150  and  152 . Antenna currents I 3  may radiate the radio-frequency signals in the second UWB communications band. Antenna currents I 3  may exhibit a relatively high current density from terminal  124  to end  116  of low band arm  102 , for example. 
     Because antenna currents I 3  are associated with a harmonic mode of low band arm  102 , antenna currents I 3  flow in opposite directions on opposing sides of line  148 . For example, antenna currents I 3  may flow in a first direction above line  148 , as shown by arrow  150 , whereas antenna currents I 3  flow in a second direction below line  148 , as shown by arrow  152 . Line  148  may represent the location along the length of low band arm  102  where antenna current I 3  exhibits a magnitude of zero (e.g., the location where there is a node in the electric field produced by low band arm  102  in the second UWB communications band). 
     Antenna resonating element  68 - 1  may also induce antenna currents I 3  at tip  78  of segment  76 , as shown by arrow  156 , and on tunable component  72 - 2  of antenna  40 - 2 , as shown by arrow  154 . Antenna currents I 3  on segment  76  and tunable component  72 - 2  may contribute to the radiative response of antenna  40 - 1  in the second UWB communications band but may exhibit lower current density than the antenna currents I 3  flowing between terminal  124  and end  116  of low band arm  102 , for example. 
     Tunable component  72 - 1  may be placed in the first tuning state while antenna feed  48 - 1  conveys antenna currents I 3 . For example, switches  144  and/or  146  of  FIG. 7  may be open, such that only inductor L of  FIGS. 7 and 8  (or inductor L and a relatively low capacitance) is coupled between antenna resonating element  68 - 1  and ground structures  94 . Because antenna currents I 3  are at a relatively high frequency (i.e., a frequency in the second UWB communications band at 8.0 GHz), the inductor L in tunable component  72 - 1  may appear as an open circuit impedance to antenna current I 3 . 
       FIG. 11  is a top view showing how antenna  40 - 1  may be used to convey radio-frequency signals (UWB signals) in the first UWB communications band at 6.5 GHz (e.g., when tunable component  72 - 1  of  FIGS. 7 and 8  and thus antenna  40 - 1  are in the second tuning state). In the second tuning state, tunable component  72 - 1  may couple a relatively high capacitance between low band arm  102  and ground structures  94  (e.g., capacitors C 1  and/or C 2  of  FIG. 7  or capacitors C 1  and C 2  of  FIG. 8 ). 
     As shown in  FIG. 11 , low band arm  102  may exhibit a harmonic mode resonance in the first UWB communications band at 6.5 GHz (e.g., while the fundamental mode of low band arm  102  concurrently covers one or more cellular telephone communications bands as shown in  FIG. 6 ). Antenna feed  48 - 1  may convey radio-frequency signals in the first ultra-wideband communications band for UWB transceiver circuitry  44  ( FIG. 5 ). Corresponding antenna currents I 4  (e.g., antenna currents in the first UWB communications band at 6.5 GHz) may flow on low band arm  102 , a portion of high band arm  100  such as first segment  110 , return path  104 , and a portion of ground structures  94 . Because of the relatively high capacitance of tunable component  72 - 1  in the second tuning state, antenna current I 4  may flow through tunable component  72 - 1 , as shown by loop path  162 . This may serve to pull the location on low band arm  102  where antenna current I 4  exhibits zero magnitude from line  148  of  FIG. 10  to line  158  of  FIG. 11  (e.g., antenna current I 4  may flow in a first direction on low band arm  102  below line  158 , as shown by the arrows of loop path  162 , and may flow in a second direction on low band arm  102  above line  158 , as shown by arrow  160 ). Because the distance between line  158  and end  116  of low band arm  102  is greater than the distance between line  148  of  FIG. 10  and end  116 , antenna  40 - 1  may support a harmonic mode resonance at lower frequencies when tunable component  72 - 1  is in the second tuning state than when tunable component  72 - 1  is in the first tuning state. This may allow antenna  40 - 1  to radiate at lower frequencies such as frequencies in the first UWB communications band at 6.5 GHz with satisfactory antenna efficiency. 
     As shown in  FIG. 11 , antenna currents I 4  may also be induced at tip  78  of segment  76 , as shown by arrow  166 , and on tunable component  72 - 2  of antenna  40 - 2 , as shown by arrow  164 . Antenna currents I 4  on segment  76  and tunable component  72 - 2  may contribute to the radiative response of antenna  40 - 1  in the first UWB communications band but may exhibit lower current density than the antenna currents I 4  flowing on antenna resonating element  68 - 1 . 
       FIG. 12  is a plot of antenna efficiency as a function of frequency for antenna  40 - 1  of  FIGS. 6, 10, and 11 . Curve  168  of  FIG. 12  plots the antenna efficiency of antenna  40 - 1  when tunable component  72 - 1  is in the first tuning state. 
     As shown by curve  168 , in the first tuning state, antenna  40 - 1  may exhibit a first response peak in a first communications band B 1  (e.g., one or more cellular ultra-high bands between 3400 MHz and 3700 MHz). The first response peak may, for example, be supported by antenna currents I 2  of  FIG. 6  and the fundamental mode of low band arm  102 . Antenna  40 - 1  may also exhibit a second response peak in a second communications band B 2  (e.g., a 5.0 GHz WLAN communications band between 5180 MHz and 5850 MHz). The second response peak may, for example, be supported by antenna currents I 1  of  FIG. 6  and the fundamental mode of high band arm  100 . Antenna  40 - 1  may also exhibit a third response peak in communications band B 4  (e.g., the second UWB communications band at 8.0 GHz, which includes frequencies between 7750 MHz and 8250 MHz). The third response peak may by supported by antenna currents I 3  of  FIG. 10  and a harmonic mode (e.g., a first harmonic, second harmonic, third harmonic, etc.) of low band arm  102 . 
     Curve  170  of  FIG. 12  plots the antenna efficiency of antenna  40 - 1  when tunable component  72 - 1  is in the second tuning state. As shown by curve  170 , in the second tuning state, antenna  40 - 1  may still exhibit the first response peak in communications band B 1  and the second response peak in communications band B 2 . However, the relatively high capacitance introduced by tunable component  72 - 1  in the second tuning state may pull the third response peak to lower frequencies in band B 3  (e.g., the first UWB communications band at 6.5 GHz, which includes frequencies between 6250 MHz and 6750 MHz). The response peak in band B 3  may by supported by antenna currents I 4  of  FIG. 11  and a harmonic mode (e.g., a first harmonic, second harmonic, third harmonic, etc.) of low band arm  102 . 
     The example of  FIG. 12  is merely illustrative. In general, curves  170  and  168  may exhibit any desired number of response peaks of any desired shape at any desired frequencies. In another suitable arrangement, tunable component  72 - 1  may include a switchable inductor and a fixed capacitor, as shown in  FIG. 13 . In the example of  FIG. 13 , tunable component  72 - 1  includes an additional inductor L 1  coupled in series with switch  172  and in parallel with capacitor C 4  and inductor L between terminals  122  and  124 . In this arrangement, antenna  40 - 1  may exhibit response curve  170  of  FIG. 12  when switch  172  is open (e.g., in an OFF state) and may exhibit response curve  168  of  FIG. 12  when switch  172  is closed (e.g., in an ON state). The length of low band arm  102  may be selected to tune the harmonic mode resonance of low band arm to the first UWB communications band at 6.5 GHz in this example. The example of  FIG. 13  is merely illustrative and, in general, tunable component  72 - 1  may include any desired number of switches, inductive components, resistive components, and/or capacitive components arranged in any desired manner between terminals  122  and  124 . 
     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: 20190829
Publication Date: 20210309
Grant Date: 20210309
Priority Date: 20190829
Inventors: YARGA, SALIH
ZHONG, JINGNI
AVSER, BILGEHAN
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/371", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/25", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/25", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/25", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 74680239