PATENT DOCUMENT

Publication Number: US-12155134-B2
Application Number: US-202016851848-A
Country: US
Kind Code: B2

Title: Electronic devices having dielectric resonator antennas with parasitic patches

Abstract:
An electronic device may be provided with a phased antenna array and a display cover layer. The phased antenna array may include a probe-fed dielectric resonator antenna that radiates through the cover layer. The antenna may include a dielectric resonating element that is excited by one or two feed probes. One or more floating parasitic elements and/or grounded parasitic elements may be patterned onto the dielectric resonating element. The parasitic elements may create boundary conditions on the dielectric resonating element that serve to isolate the antenna from cross polarization interference.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a housing; 
 a display having a display cover layer mounted to the housing; and 
 a probe-fed dielectric resonator antenna in the housing and configured to convey radio-frequency signals in a frequency band greater than 10 GHz through the display cover layer, wherein the probe-fed dielectric resonator antenna comprises:
 a parasitic element configured to isolate the probe-fed dielectric resonator antenna from cross-polarization interference. 
 
 
     
     
       2. The electronic device of  claim 1 , wherein the probe-fed dielectric resonator antenna further comprises:
 a feed probe on a dielectric resonating element, wherein the feed probe is configured to excite the dielectric resonating element to resonate in the frequency band. 
 
     
     
       3. The electronic device of  claim 2 , wherein the dielectric resonating element comprises a first sidewall, a second sidewall, a third sidewall opposite the first sidewall, and a fourth sidewall opposite the second sidewall, the feed probe being coupled to the first sidewall. 
     
     
       4. The electronic device of  claim 3 , wherein the parasitic element is coupled to the third sidewall and is aligned with the feed probe. 
     
     
       5. The electronic device of  claim 4 , further comprising:
 a substrate, wherein the dielectric resonating element is mounted to the substrate; and 
 a radio-frequency transmission line on the substrate and coupled to the feed probe, wherein the dielectric resonating element has a first end at the display and an opposing second end at the substrate, the probe-fed dielectric resonator antenna further comprising:
 an additional parasitic element coupled to the dielectric resonating element at the first end of the dielectric resonating element. 
 
 
     
     
       6. The electronic device of  claim 4 , wherein the probe-fed dielectric resonator antenna further comprises:
 an additional feed probe coupled to the second sidewall of the dielectric resonating element, wherein the additional feed probe is configured to excite the dielectric resonating element; and 
 an additional parasitic element configured to isolate the probe-fed dielectric resonator antenna from cross-polarization interference, wherein the additional parasitic element is coupled to the fourth sidewall and is aligned with the additional feed probe. 
 
     
     
       7. The electronic device of  claim 6 , wherein the dielectric resonating element has a first end at the feed probe and has an opposing second end, the probe-fed dielectric resonator antenna further comprising:
 a first floating conductive patch coupled to the first sidewall at the second end; 
 a second floating conductive patch coupled to the second sidewall at the second end; 
 a third floating conductive patch coupled to the third sidewall at the second end, wherein the third floating conductive patch is aligned with the first floating conductive patch; and 
 a fourth floating conductive patch coupled to the fourth sidewall at the second end, wherein the fourth floating conductive patch is aligned with the second floating conductive patch. 
 
     
     
       8. The electronic device of  claim 3 , wherein the parasitic element is coupled to the second sidewall. 
     
     
       9. The electronic device of  claim 8 , wherein the probe-fed dielectric resonator antenna further comprises:
 an additional parasitic element configured to isolate the probe-fed dielectric resonator antenna from cross-polarization interference, wherein the additional parasitic element is coupled to the fourth sidewall. 
 
     
     
       10. The electronic device of  claim 9 , wherein the third sidewall is free of conductive material. 
     
     
       11. The electronic device of  claim 9 , further comprising:
 a substrate, wherein the dielectric resonating element is mounted to a surface of the substrate; 
 a radio-frequency transmission line on the substrate and coupled to the feed probe; and 
 ground traces on the surface of the substrate, wherein the parasitic element and the additional parasitic element are coupled to the ground traces. 
 
     
     
       12. The electronic device of  claim 1 , wherein the housing comprises peripheral conductive housing structures that extend around a periphery of the electronic device, the display cover layer is mounted to the peripheral conductive housing structures, and the electronic device further comprises:
 a notch in the peripheral conductive housing structures, wherein the probe-fed dielectric resonating antenna is aligned with the notch and is configured to convey the radio-frequency signals through the notch. 
 
     
     
       13. The electronic device defined in  claim 1 , wherein the housing comprises peripheral conductive housing structures that extend around a periphery of the electronic device, the display cover layer is mounted to the peripheral conductive housing structures, the display comprises a display module configured to emit light through the display cover layer, the display module comprises a notch, the notch has edges defined by the display module and the peripheral conductive housing structures, and the electronic device further comprises:
 an audio speaker aligned with the notch; and 
 an image sensor aligned with the notch, wherein the probe-fed dielectric resonator antenna is aligned with the notch and is configured to convey the radio-frequency signals through the notch. 
 
     
     
       14. An antenna comprising:
 a dielectric resonating element having a bottom surface, a top surface, and first, second, third, and fourth sidewalls extending from the bottom surface to the top surface, wherein the first sidewall opposes the third sidewall and the second sidewall opposes the fourth sidewall; 
 a feed probe coupled to the first sidewall, wherein the feed probe is configured to excite the dielectric resonating element to resonate in a frequency band greater than 10 GHz; and 
 a floating parasitic patch coupled to the third sidewall and overlapping the feed probe. 
 
     
     
       15. The antenna of  claim 14 , further comprising:
 an additional feed probe coupled to the second sidewall, wherein the additional feed probe is configured to excite the dielectric resonating element to resonate in the frequency band; and 
 an additional floating parasitic patch coupled to the fourth sidewall and overlapping the additional feed probe. 
 
     
     
       16. The antenna of  claim 15 , wherein the dielectric resonating element has a first end at the bottom surface and a second end at the top surface, the feed probe, the additional feed probe, the floating parasitic patch, and the additional floating parasitic patch being located at the first end of the dielectric resonating element. 
     
     
       17. The antenna of  claim 16 , further comprising:
 at least one floating parasitic patch coupled to the dielectric resonating element at the second end of the dielectric resonating element. 
 
     
     
       18. An antenna comprising:
 a dielectric resonating element having a bottom surface, a top surface, and first, second, third, and fourth sidewalls extending from the bottom surface to the top surface, wherein the first sidewall opposes the third sidewall and the second sidewall opposes the fourth sidewall; 
 a feed probe coupled to the first sidewall, wherein the feed probe is configured to excite the dielectric resonating element to resonate in a frequency band greater than 10 GHz; 
 a grounded parasitic patch coupled to the second sidewall; and 
 an additional parasitic patch coupled to the dielectric resonating element. 
 
     
     
       19. The antenna of  claim 18 , wherein the additional parasitic patch is grounded, is coupled to the fourth sidewall, and overlaps the grounded parasitic patch. 
     
     
       20. The antenna of  claim 19 , wherein the dielectric resonating element has a first end at the bottom surface and a second end at the top surface, the feed probe, the grounded parasitic patch, and the additional grounded parasitic patch being located at the first end of the dielectric resonating element.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless circuitry. 
     Electronic devices often include wireless circuitry. For example, cellular telephones, computers, and other devices often contain antennas and wireless transceivers for supporting wireless communications. 
     It may be desirable to support wireless communications in millimeter wave and centimeter wave communications bands. Millimeter wave communications, which are sometimes referred to as extremely high frequency (EHF) communications, and centimeter wave communications involve communications at frequencies of about 10-300 GHz. Operation at these frequencies may support high bandwidths but may raise significant challenges. For example, radio-frequency communications in millimeter and centimeter wave communications bands can be characterized by substantial attenuation and/or distortion during signal propagation through various mediums. In addition, the presence of conductive electronic device components can make it difficult to incorporate circuitry for handling millimeter and centimeter wave communications into the electronic device. In scenarios where the antennas cover multiple polarizations, cross-polarization interference can also limit antenna performance. 
     It would therefore be desirable to be able to provide electronic devices with improved wireless circuitry such as wireless circuitry that supports millimeter and centimeter wave communications. 
     SUMMARY 
     An electronic device may be provided with a housing, a display, and wireless circuitry. The housing may include peripheral conductive housing structures that run around a periphery of the device. The display may include a display cover layer mounted to the peripheral conductive housing structures. The wireless circuitry may include a phased antenna array that conveys radio-frequency signals in one or more frequency bands between 10 GHz and 300 GHz. The phased antenna array may convey the radio-frequency signals through the display cover layer or other dielectric cover layers in the device. 
     The phased antenna array may include probe-fed dielectric resonator antennas. Each probe-fed dielectric resonator antenna may include a dielectric resonating element formed from a column of relatively high dielectric constant material that is embedded within a surrounding dielectric substrate. The dielectric resonating element may be mounted to a flexible printed circuit. The dielectric resonating element may have first, second, third, and fourth sidewalls extending from the flexible printed circuit to the display. The third sidewall may oppose the first sidewall whereas the fourth sidewall opposes the second sidewall. 
     A feed probe may be formed from a patch of conductive traces patterned on the first sidewall of the dielectric resonating element. In a first example, an additional feed probe may be formed from an additional patch of conductive traces patterned on the second sidewall. A first floating parasitic patch may be coupled to the third sidewall and may overlap the first feed probe. A second floating parasitic patch may be coupled to the fourth sidewall and may overlap the second feed probe. An additional set of floating parasitic patches may be formed at an opposing end of the dielectric resonating element if desired. In another example, a first grounded parasitic patch may be coupled to the second sidewall and a second grounded parasitic patch may be coupled to the fourth sidewall. The second grounded patch may overlap the first grounded patch. The parasitic patches may create boundary conditions on the dielectric resonating element for the feed probes and may serve to isolate the antenna from cross-polarization interference. 
    
    
     
       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 phased antenna array that may be adjusted using control circuitry to direct a beam of signals in accordance with some embodiments. 
         FIG.  5    is a cross-sectional side view of an illustrative electronic device having phased antenna arrays for radiating through different sides of the device in accordance with some embodiments. 
         FIG.  6    is a cross-sectional side view of an illustrative probe-fed dielectric resonator antenna that may be mounted within an electronic device in accordance with some embodiments. 
         FIG.  7    is a perspective view of an illustrative probe-fed dielectric resonator antenna for covering multiple polarizations in accordance with some embodiments. 
         FIG.  8    is a cross-sectional side view of an illustrative probe-fed dielectric resonator antenna that overlaps an opening in ground traces in accordance with some embodiments. 
         FIG.  9    is a top-down view of an illustrative probe-fed dielectric resonator antenna that overlaps an opening in ground traces in accordance with some embodiments. 
         FIG.  10    is a top-down view of an illustrative probe-fed dielectric resonator antenna having multiple feed probes and floating parasitic patches for mitigating cross-polarization interference in accordance with some embodiments. 
         FIG.  11    is a cross-sectional side view of an illustrative probe-fed dielectric resonator antenna having multiple feed probes and floating parasitic patches for mitigating cross-polarization interference in accordance with some embodiments. 
         FIG.  12    is a perspective view of an illustrative probe-fed dielectric resonator antenna having floating parasitic patches at an end of the antenna opposite to feed probes for the antenna in accordance with some embodiments. 
         FIG.  13    is a top-down view of an illustrative probe-fed dielectric resonating antenna having a single feed probe and grounded parasitic patches for mitigating cross-polarization interference in accordance with some embodiments. 
         FIG.  14    is a side view of an illustrative probe-fed dielectric resonating antenna having a single feed probe and grounded parasitic patches for mitigating cross-polarization interference in accordance with some embodiments. 
         FIG.  15    is a plot of antenna performance (return loss) as a function of frequency for illustrative probe-fed dielectric resonating antennas having different numbers of grounded parasitic patches in accordance with some embodiments. 
         FIG.  16    is a top-down view of an illustrative electronic device having probe-fed dielectric resonator antennas aligned with a notch in peripheral conductive housing structures in accordance with some embodiments. 
         FIG.  17    is a top-down view of an illustrative electronic device having probe-fed dielectric resonator antennas aligned with a notch in a display module in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG.  1    may contain wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include phased antenna arrays that are used for performing wireless communications using millimeter and centimeter wave signals. Millimeter wave signals, which are sometimes referred to as extremely high frequency (EHF) signals, propagate at frequencies above about 30 GHz (e.g., at 60 GHz or other frequencies between about 30 GHz and 300 GHz). Centimeter wave signals propagate at frequencies between about 10 GHz and 30 GHz. If desired, device  10  may also contain antennas for handling satellite navigation system signals, cellular telephone signals, local wireless area network signals, near-field communications, light-based wireless communications, or other wireless communications. 
     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. Conductive portions of 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 ledge 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 of display  14  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. Inactive area IA may include a recessed region such as notch  8  that extends into active area AA. Active area AA may, for example, be defined by the lateral area of a display module for display  14  (e.g., a display module that includes pixel circuitry, touch sensor circuitry, etc.). The display module may have a recess or notch in upper region  20  of device  10  that is free from active display circuitry (i.e., that forms notch  8  of inactive area IA). Notch  8  may be a substantially rectangular region that is surrounded (defined) on three sides by active area AA and on a fourth side by peripheral conductive housing structures  12 W. 
     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  in notch  8  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. The conductive segments that are formed in this way may form parts of antennas in device  10  if desired. Other dielectric openings may be formed in peripheral conductive housing structures  12 W (e.g., dielectric openings other than gaps  18 ) and may serve as dielectric antenna windows for antennas mounted within the interior of device  10 . Antennas within device  10  may be aligned with the dielectric antenna windows for conveying radio-frequency signals through peripheral conductive housing structures  12 W. Antennas within device  10  may also be aligned with inactive area IA of display  14  for conveying radio-frequency signals through display  14 . 
     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. Other antennas for covering any other desired frequencies may also be mounted at any desired locations within the interior of device  10 . The example of  FIG.  1    is merely illustrative. If desired, housing  12  may have other shapes (e.g., a square shape, cylindrical shape, spherical shape, combinations of these and/or different shapes, 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  30 . Storage circuitry  30  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  32 . Processing circuitry  32  may be used to control the operation of device  10 . Processing circuitry  32  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  30  (e.g., storage circuitry  30  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  30  may be executed by processing circuitry  32 . 
     Control circuitry  28  may be used to run software on device  10  such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, 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 WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other WPAN protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, antenna-based spatial ranging protocols (e.g., radio detection and ranging (RADAR) protocols or other desired range detection protocols for signals conveyed at millimeter and centimeter wave frequencies), etc. Each communication 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  24 . Input-output circuitry  24  may include input-output devices  26 . Input-output devices  26  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  26  may include user interface devices, data port devices, sensors, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, gyroscopes, accelerometers or other components that can detect motion and device orientation relative to the Earth, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, and other sensors and input-output components. 
     Input-output circuitry  24  may include wireless circuitry such as wireless circuitry  34  for wireles sly conveying radio-frequency signals. 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  32  and/or storage circuitry that forms a part of storage circuitry  30  of control circuitry  28  (e.g., portions of control circuitry  28  may be implemented on wireless circuitry  34 ). As an example, control circuitry  28  may include baseband processor circuitry or other control components that form a part of wireless circuitry  34 . 
     Wireless circuitry  34  may include millimeter and centimeter wave transceiver circuitry such as millimeter/centimeter wave transceiver circuitry  38 . Millimeter/centimeter wave transceiver circuitry  38  may support communications at frequencies between about 10 GHz and 300 GHz. For example, millimeter/centimeter wave transceiver circuitry  38  may support communications in Extremely High Frequency (EHF) or millimeter wave communications bands between about 30 GHz and 300 GHz and/or in centimeter wave communications bands between about 10 GHz and 30 GHz (sometimes referred to as Super High Frequency (SHF) bands). As examples, millimeter/centimeter wave transceiver circuitry  38  may support communications in an IEEE K communications band between about 18 GHz and 27 GHz, a K a  communications band between about 26.5 GHz and 40 GHz, a K u  communications band between about 12 GHz and 18 GHz, a V communications band between about 40 GHz and 75 GHz, a W communications band between about 75 GHz and 110 GHz, or any other desired frequency band between approximately 10 GHz and 300 GHz. If desired, millimeter/centimeter wave transceiver circuitry  38  may support IEEE 802.11ad communications at 60 GHz and/or 5 th  generation mobile networks or 5 th  generation wireless systems (5G) communications bands between 27 GHz and 90 GHz. Millimeter/centimeter wave transceiver circuitry  38  may be formed from one or more integrated circuits (e.g., multiple integrated circuits mounted on a common printed circuit in a system-in-package device, one or more integrated circuits mounted on different substrates, etc.). 
     If desired, millimeter/centimeter wave transceiver circuitry  38  (sometimes referred to herein simply as transceiver circuitry  38  or millimeter/centimeter wave circuitry  38 ) may perform spatial ranging operations using radio-frequency signals at millimeter and/or centimeter wave signals that are transmitted and received by millimeter/centimeter wave transceiver circuitry  38 . The received signals may be a version of the transmitted signals that have been reflected off of external objects and back towards device  10 . Control circuitry  28  may process the transmitted and received signals to detect or estimate a range between device  10  and one or more external objects in the surroundings of device  10  (e.g., objects external to device  10  such as the body of a user or other persons, other devices, animals, furniture, walls, or other objects or obstacles in the vicinity of device  10 ). If desired, control circuitry  28  may also process the transmitted and received signals to identify a two or three-dimensional spatial location of the external objects relative to device  10 . 
     Spatial ranging operations performed by millimeter/centimeter wave transceiver circuitry  38  are unidirectional. Millimeter/centimeter wave transceiver circuitry  38  may perform bidirectional communications with external wireless equipment. Bidirectional communications involve both the transmission of wireless data by millimeter/centimeter wave transceiver circuitry  38  and the reception of wireless data that has been transmitted by external wireless equipment. The wireless data may, for example, include data that has been encoded into corresponding data packets such as wireless data associated with a telephone call, streaming media content, internet browsing, wireless data associated with software applications running on device  10 , email messages, etc. 
     If desired, wireless circuitry  34  may include transceiver circuitry for handling communications at frequencies below 10 GHz such as non-millimeter/centimeter wave transceiver circuitry  36 . Non-millimeter/centimeter wave transceiver circuitry  36  may include wireless local area network (WLAN) transceiver circuitry that handles 2.4 GHz and 5 GHz bands for Wi-Fi® (IEEE 802.11) communications, wireless personal area network (WPAN) transceiver circuitry that handles the 2.4 GHz Bluetooth® communications band, cellular telephone transceiver circuitry that handles cellular telephone communications bands from 700 to 960 MHz, 1710 to 2170 MHz, 2300 to 2700 MHz, and/or or any other desired cellular telephone communications bands between 600 MHz and 4000 MHz, GPS receiver circuitry that receives GPS signals at 1575 MHz or signals for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz), television receiver circuitry, AM/FM radio receiver circuitry, paging system transceiver circuitry, ultra-wideband (UWB) transceiver circuitry, near field communications (NFC) circuitry, etc. Non-millimeter/centimeter wave transceiver circuitry  36  and millimeter/centimeter wave transceiver circuitry  38  may each include one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive radio-frequency components, switching circuitry, transmission line structures, and other circuitry for handling radio-frequency signals. Non-millimeter/centimeter wave transceiver circuitry  36  may be omitted if desired. 
     Wireless circuitry  34  may include antennas  40 . Non-millimeter/centimeter wave transceiver circuitry  36  may convey radio-frequency signals below 10 GHz using one or more antennas  40 . Millimeter/centimeter wave transceiver circuitry  38  may convey radio-frequency signals above 10 GHz (e.g., at millimeter wave and/or centimeter wave frequencies) using antennas  40 . In general, transceiver circuitry  36  and  38  may be configured to cover (handle) any suitable communications (frequency) bands of interest. The transceiver circuitry may convey radio-frequency signals using antennas  40  (e.g., antennas  40  may convey the radio-frequency signals for the transceiver circuitry). The term “convey radio-frequency signals” as used herein means the transmission and/or reception of the radio-frequency signals (e.g., for performing unidirectional and/or bidirectional wireless communications with external wireless communications equipment). Antennas  40  may transmit the radio-frequency signals by radiating the radio-frequency signals into free space (or to freespace through intervening device structures such as a dielectric cover layer). Antennas  40  may additionally or alternatively receive the radio-frequency signals from free space (e.g., through intervening devices structures such as a dielectric cover layer). The transmission and reception of radio-frequency signals by antennas  40  each involve the excitation or resonance of antenna currents on an antenna resonating element in the antenna by the radio-frequency signals within the frequency band(s) of operation of the antenna. 
     In satellite navigation system links, cellular telephone links, and other long-range links, radio-frequency signals are typically used to convey data over thousands of feet or miles. In Wi-Fi® and Bluetooth® links at 2.4 and 5 GHz and other short-range wireless links, radio-frequency signals are typically used to convey data over tens or hundreds of feet. Millimeter/centimeter wave transceiver circuitry  38  may convey radio-frequency signals over short distances that travel over a line-of-sight path. To enhance signal reception for millimeter and centimeter wave communications, phased antenna arrays and beam steering techniques may be used (e.g., schemes in which antenna signal phase and/or magnitude for each antenna in an array are adjusted to perform beam steering). Antenna diversity schemes may also be used 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. 
     Antennas  40  in wireless circuitry  34  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from stacked patch antenna structures, loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, monopole antenna structures, dipole antenna structures, helical antenna structures, Yagi (Yagi-Uda) antenna structures, hybrids of these designs, etc. In another suitable arrangement, antennas  40  may include antennas with dielectric resonating elements such as dielectric resonator antennas. 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 non-millimeter/centimeter wave wireless link for non-millimeter/centimeter wave transceiver circuitry  36  and another type of antenna may be used in conveying radio-frequency signals at millimeter and/or centimeter wave frequencies for millimeter/centimeter wave transceiver circuitry  38 . Antennas  40  that are used to convey radio-frequency signals at millimeter and centimeter wave frequencies may be arranged in one or more phased antenna arrays. 
     A schematic diagram of an antenna  40  that may be formed in a phased antenna array for conveying radio-frequency signals at millimeter and centimeter wave frequencies is shown in  FIG.  3   . As shown in  FIG.  3   , antenna  40  may be coupled to millimeter/centimeter (MM/CM) wave transceiver circuitry  38 . Millimeter/centimeter wave transceiver circuitry  38  may be coupled to antenna feed  44  of antenna  40  using a transmission line path that includes radio-frequency transmission line  42 . Radio-frequency transmission line  42  may include a positive signal conductor such as signal conductor  46  and may include a ground conductor such as ground conductor  48 . Ground conductor  48  may be coupled to the antenna ground for antenna  40  (e.g., over a ground antenna feed terminal of antenna feed  44  located at the antenna ground). Signal conductor  46  may be coupled to the antenna resonating element for antenna  40 . For example, signal conductor  46  may be coupled to a positive antenna feed terminal of antenna feed  44  located at the antenna resonating element. 
     In another suitable arrangement, antenna  40  may be a probe-fed antenna that is fed using a feed probe. In this arrangement, antenna feed  44  may be implemented as a feed probe. Signal conductor  46  may be coupled to the feed probe. Radio-frequency transmission line  42  may convey radio-frequency signals to and from the feed probe. When radio-frequency signals are being transmitted over the feed probe and the antenna, the feed probe may excite the resonating element for the antenna (e.g., may excite electromagnetic resonant modes of a dielectric antenna resonating element for antenna  40 ). The resonating element may radiate the radio-frequency signals in response to excitation by the feed probe. Similarly, when radio-frequency signals are received by the antenna (e.g., from free space), the radio-frequency signals may excite the resonating element for the antenna (e.g., may excite electromagnetic resonant modes of the dielectric antenna resonating element for antenna  40 ). This may produce antenna currents on the feed probe and the corresponding radio-frequency signals may be passed to the transceiver circuitry over the radio-frequency transmission line. 
     Radio-frequency transmission line  42  may include a stripline transmission line (sometimes referred to herein simply as a stripline), a coaxial cable, a coaxial probe realized by metalized vias, a microstrip transmission line, an edge-coupled microstrip transmission line, an edge-coupled stripline transmission lines, a waveguide structure, combinations of these, etc. Multiple types of transmission lines may be used to form the transmission line path that couples millimeter/centimeter wave transceiver circuitry  38  to antenna feed  44 . Filter circuitry, switching circuitry, impedance matching circuitry, phase shifter circuitry, amplifier circuitry, and/or other circuitry may be interposed on radio-frequency transmission line  42 , if desired. 
     Radio-frequency transmission lines in device  10  may be integrated into ceramic substrates, rigid printed circuit boards, and/or flexible printed circuits. In one suitable arrangement, radio-frequency transmission lines in device  10  may be integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). 
       FIG.  4    shows how antennas  40  for handling radio-frequency signals at millimeter and centimeter wave frequencies may be formed in a phased antenna array. As shown in  FIG.  4   , phased antenna array  54  (sometimes referred to herein as array  54 , antenna array  54 , or array  54  of antennas  40 ) may be coupled to radio-frequency transmission lines  42 . For example, a first antenna  40 - 1  in phased antenna array  54  may be coupled to a first radio-frequency transmission line  42 - 1 , a second antenna  40 - 2  in phased antenna array  54  may be coupled to a second radio-frequency transmission line  42 - 2 , an Nth antenna  40 -N in phased antenna array  54  may be coupled to an Nth radio-frequency transmission line  42 -N, etc. While antennas  40  are described herein as forming a phased antenna array, the antennas  40  in phased antenna array  54  may sometimes also be referred to as collectively forming a single phased array antenna. 
     Antennas  40  in phased antenna array  54  may be arranged in any desired number of rows and columns or in any other desired pattern (e.g., the antennas need not be arranged in a grid pattern having rows and columns). During signal transmission operations, radio-frequency transmission lines  42  may be used to supply signals (e.g., radio-frequency signals such as millimeter wave and/or centimeter wave signals) from millimeter/centimeter wave transceiver circuitry  38  ( FIG.  3   ) to phased antenna array  54  for wireless transmission. During signal reception operations, radio-frequency transmission lines  42  may be used to supply signals received at phased antenna array  54  (e.g., from external wireless equipment or transmitted signals that have been reflected off of external objects) to millimeter/centimeter wave transceiver circuitry  38  ( FIG.  3   ). 
     The use of multiple antennas  40  in phased antenna array  54  allows beam steering arrangements to be implemented by controlling the relative phases and magnitudes (amplitudes) of the radio-frequency signals conveyed by the antennas. In the example of  FIG.  4   , antennas  40  each have a corresponding radio-frequency phase and magnitude controller  50  (e.g., a first phase and magnitude controller  50 - 1  interposed on radio-frequency transmission line  42 - 1  may control phase and magnitude for radio-frequency signals handled by antenna  40 - 1 , a second phase and magnitude controller  50 - 2  interposed on radio-frequency transmission line  42 - 2  may control phase and magnitude for radio-frequency signals handled by antenna  40 - 2 , an Nth phase and magnitude controller  50 -N interposed on radio-frequency transmission line  42 -N may control phase and magnitude for radio-frequency signals handled by antenna  40 -N, etc.). 
     Phase and magnitude controllers  50  may each include circuitry for adjusting the phase of the radio-frequency signals on radio-frequency transmission lines  42  (e.g., phase shifter circuits) and/or circuitry for adjusting the magnitude of the radio-frequency signals on radio-frequency transmission lines  42  (e.g., power amplifier and/or low noise amplifier circuits). Phase and magnitude controllers  50  may sometimes be referred to collectively herein as beam steering circuitry (e.g., beam steering circuitry that steers the beam of radio-frequency signals transmitted and/or received by phased antenna array  54 ). 
     Phase and magnitude controllers  50  may adjust the relative phases and/or magnitudes of the transmitted signals that are provided to each of the antennas in phased antenna array  54  and may adjust the relative phases and/or magnitudes of the received signals that are received by phased antenna array  54 . Phase and magnitude controllers  50  may, if desired, include phase detection circuitry for detecting the phases of the received signals that are received by phased antenna array  54 . The term “beam” or “signal beam” may be used herein to collectively refer to wireless signals that are transmitted and received by phased antenna array  54  in a particular direction. The signal beam may exhibit a peak gain that is oriented in a particular pointing direction at a corresponding pointing angle (e.g., based on constructive and destructive interference from the combination of signals from each antenna in the phased antenna array). The term “transmit beam” may sometimes be used herein to refer to radio-frequency signals that are transmitted in a particular direction whereas the term “receive beam” may sometimes be used herein to refer to radio-frequency signals that are received from a particular direction. 
     If, for example, phase and magnitude controllers  50  are adjusted to produce a first set of phases and/or magnitudes for transmitted radio-frequency signals, the transmitted signals will form a transmit beam as shown by beam B 1  of  FIG.  4    that is oriented in the direction of point A. If, however, phase and magnitude controllers  50  are adjusted to produce a second set of phases and/or magnitudes for the transmitted signals, the transmitted signals will form a transmit beam as shown by beam B 2  that is oriented in the direction of point B. Similarly, if phase and magnitude controllers  50  are adjusted to produce the first set of phases and/or magnitudes, radio-frequency signals (e.g., radio-frequency signals in a receive beam) may be received from the direction of point A, as shown by beam B 1 . If phase and magnitude controllers  50  are adjusted to produce the second set of phases and/or magnitudes, radio-frequency signals may be received from the direction of point B, as shown by beam B 2 . 
     Each phase and magnitude controller  50  may be controlled to produce a desired phase and/or magnitude based on a corresponding control signal  52  received from control circuitry  28  of  FIG.  2    (e.g., the phase and/or magnitude provided by phase and magnitude controller  50 - 1  may be controlled using control signal  52 - 1 , the phase and/or magnitude provided by phase and magnitude controller  50 - 2  may be controlled using control signal  52 - 2 , etc.). If desired, the control circuitry may actively adjust control signals  52  in real time to steer the transmit or receive beam in different desired directions over time. Phase and magnitude controllers  50  may provide information identifying the phase of received signals to control circuitry  28  if desired. 
     When performing wireless communications using radio-frequency signals at millimeter and centimeter wave frequencies, the radio-frequency signals are conveyed over a line of sight path between phased antenna array  54  and external communications equipment. If the external object is located at point A of  FIG.  4   , phase and magnitude controllers  50  may be adjusted to steer the signal beam towards point A (e.g., to steer the pointing direction of the signal beam towards point A). Phased antenna array  54  may transmit and receive radio-frequency signals in the direction of point A. Similarly, if the external communications equipment is located at point B, phase and magnitude controllers  50  may be adjusted to steer the signal beam towards point B (e.g., to steer the pointing direction of the signal beam towards point B). Phased antenna array  54  may transmit and receive radio-frequency signals in the direction of point B. In the example of  FIG.  4   , beam steering is shown as being performed over a single degree of freedom for the sake of simplicity (e.g., towards the left and right on the page of  FIG.  4   ). However, in practice, the beam may be steered over two or more degrees of freedom (e.g., in three dimensions, into and out of the page and to the left and right on the page of  FIG.  4   ). Phased antenna array  54  may have a corresponding field of view over which beam steering can be performed (e.g., in a hemisphere or a segment of a hemisphere over the phased antenna array). If desired, device  10  may include multiple phased antenna arrays that each face a different direction to provide coverage from multiple sides of the device. 
       FIG.  5    is a cross-sectional side view of device  10  in an example where device  10  has multiple phased antenna arrays. As shown in  FIG.  5   , peripheral conductive housing structures  12 W may extend around the (lateral) periphery of device  10  and may extend from rear housing wall  12 R to display  14 . Display  14  may have a display module such as display module  68  (sometimes referred to as a display panel). Display module  68  may include pixel circuitry, touch sensor circuitry, force sensor circuitry, and/or any other desired circuitry for forming active area AA of display  14 . Display  14  may include a dielectric cover layer such as display cover layer  56  that overlaps display module  68 . Display module  68  may emit image light and may receive sensor input through display cover layer  56 . Display cover layer  56  and display  14  may be mounted to peripheral conductive housing structures  12 W. The lateral area of display  14  that does not overlap display module  68  may form inactive area IA of display  14 . 
     Device  10  may include multiple phased antenna arrays  54  such as a rear-facing phased antenna array  54 - 1 . As shown in  FIG.  5   , phased antenna array  54 - 1  may transmit and receive radio-frequency signals  60  at millimeter and centimeter wave frequencies through rear housing wall  12 R. In scenarios where rear housing wall  12 R includes metal portions, radio-frequency signals  60  may be conveyed through an aperture or opening in the metal portions of rear housing wall  12 R or may be conveyed through other dielectric portions of rear housing wall  12 R. The aperture may be overlapped by a dielectric cover layer or dielectric coating that extends across the lateral area of rear housing wall  12 R (e.g., between peripheral conductive housing structures  12 W). Phased antenna array  54 - 1  may perform beam steering for radio-frequency signals  60  across the hemisphere below device  10 , as shown by arrow  62 . 
     Phased antenna array  54 - 1  may be mounted to a substrate such as substrate  64 . Substrate  64  may be an integrated circuit chip, a flexible printed circuit, a rigid printed circuit board, or other substrate. Substrate  64  may sometimes be referred to herein as antenna module  64 . If desired, transceiver circuitry (e.g., millimeter/centimeter wave transceiver circuitry  38  of  FIG.  2   ) may be mounted to antenna module  64 . Phased antenna array  54 - 1  may be adhered to rear housing wall  12 R using adhesive, may be pressed against (e.g., in contact with) rear housing wall  12 R, or may be spaced apart from rear housing wall  12 R. 
     The field of view of phased antenna array  54 - 1  is limited to the hemisphere under the rear face of device  10 . Display module  68  and other components  58  (e.g., portions of input-output circuitry  24  or control circuitry  28  of  FIG.  2   , a battery for device  10 , etc.) in device  10  include conductive structures. If care is not taken, these conductive structures may block radio-frequency signals from being conveyed by a phased antenna array within device  10  across the hemisphere over the front face of device  10 . While an additional phased antenna array for covering the hemisphere over the front face of device  10  may be mounted against display cover layer  56  within inactive area IA, there may be insufficient space between the lateral periphery of display module  68  and peripheral conductive housing structures  12 W to form all of the circuitry and radio-frequency transmission lines necessary to fully support the phased antenna array. 
     In order to mitigate these issues and provide coverage through the front face of device  10 , a front-facing phased antenna array may be mounted within peripheral region  66  of device  10 . The antennas in the front-facing phased antenna array may include dielectric resonator antennas. Dielectric resonator antennas may occupy less area in the X-Y plane of  FIG.  5    than other types of antennas such as patch antennas and slot antennas. Implementing the antennas as dielectric resonator antennas may allow the radiating elements of the front-facing phased antenna array to fit within inactive area IA between display module  68  and peripheral conductive housing structures  12 W. At the same time, the radio-frequency transmission lines and other components for the phased antenna array may be located behind (under) display module  68 . 
       FIG.  6    is a cross-sectional side view of an illustrative dielectric resonator antenna in a front-facing phased antenna array for device  10 . As shown in  FIG.  6   , device  10  may include a front-facing phased antenna array having a given antenna  40  (e.g., mounted within peripheral region  66  of  FIG.  5   ). Antenna  40  of  FIG.  6    may be a dielectric resonator antenna. In this example, antenna  40  includes a dielectric resonating element  92  mounted to an underlying substrate such as flexible printed circuit  72 . This example is merely illustrative and, if desired, flexible printed circuit  72  may be replaced with a rigid printed circuit board, a plastic substrate, or any other desired substrate. 
     Flexible printed circuit  72  has a lateral area (e.g., in the X-Y plane of  FIG.  6   ) that extends along rear housing wall  12 R. Flexible printed circuit  72  may be adhered to rear housing wall  12 R using adhesive, may be pressed against (e.g., placed in contact with) rear housing wall  12 R, or may be separated from rear housing wall  12 R. Flexible printed circuit  72  may have a first end at antenna  40  and an opposing second end coupled to the millimeter/centimeter wave transceiver circuitry in device  10  (e.g., millimeter/centimeter wave transceiver circuitry  38  of  FIG.  2   ). In one suitable arrangement, the second end of flexible printed circuit  72  may be coupled to antenna module  64  of  FIG.  5   . 
     As shown in  FIG.  6   , flexible printed circuit  72  may include stacked dielectric layers  70 . Dielectric layers  70  may include polyimide, ceramic, liquid crystal polymer, plastic, and/or any other desired dielectric materials. Conductive traces such as conductive traces  82  may be patterned on a top surface  76  of flexible printed circuit  72 . Conductive traces such as conductive traces  80  may be patterned on an opposing bottom surface  78  of flexible printed circuit  72 . Conductive traces  80  may be held at a ground potential and may therefore sometimes be referred to herein as ground traces  80 . Ground traces  80  may be shorted to additional ground traces within flexible printed circuit  72  and/or on top surface  76  of flexible printed circuity  72  using conducive vias that extend through flexible printed circuit  72  (not shown in  FIG.  6    for the sake of clarity). Ground traces  80  may form part of the antenna ground for antenna  40 . Ground traces  80  may be coupled to a system ground in device  10  (e.g., using solder, welds, conductive adhesive, conductive tape, conductive brackets, conductive pins, conductive screws, conductive clips, combinations of these, etc.). For example, ground traces  80  may be coupled to peripheral conductive housing structures  12 W, conductive portions of rear housing wall  12 R, or other grounded structures in device  10 . The example of  FIG.  6    in which conductive traces  82  are formed on top surface  76  and ground traces  80  are formed on bottom surface  78  of flexible printed circuit  72  is merely illustrative. If desired, one or more dielectric layers  70  may be layered over conductive traces  82  and/or one or more dielectric layers  70  may be layered under ground traces  80 . 
     Antenna  40  may be fed using a radio-frequency transmission line that is formed on and/or embedded within flexible printed circuit  72  such as radio-frequency transmission line  74 . Radio-frequency transmission line  74  (e.g., a given radio-frequency transmission line  42  of  FIG.  3   ) may include ground traces  80  and conductive traces  82 . The portion of ground traces  80  overlapping conductive traces  82  may form the ground conductor for radio-frequency transmission line  74  (e.g., ground conductor  48  of  FIG.  3   ). Conductive traces  82  may form the signal conductor for radio-frequency transmission line  74  (e.g., signal conductor  46  of  FIG.  3   ) and may therefore sometimes be referred to herein as signal traces  82 . Radio-frequency transmission line  74  may convey radio-frequency signals between antenna  40  and the millimeter/centimeter wave transceiver circuitry. The example of  FIG.  6    in which antenna  40  is fed using signal traces  82  and ground traces  80  is merely illustrative. In general, antenna  40  may be fed using any desired transmission line structures in and/or on flexible printed circuit  72 . 
     Dielectric resonating element  92  of antenna  40  may be formed from a column (pillar) of dielectric material mounted to top surface  76  of flexible printed circuit  72 . If desired, dielectric resonating element  92  may be embedded within (e.g., laterally surrounded by) a dielectric substrate mounted to top surface  76  of flexible printed circuit  72  such as dielectric substrate  90 . Dielectric substrate  90  and dielectric resonating element  92  extend from a bottom surface  100  at flexible printed circuit  72  to an opposing top surface  98  at display  14 . 
     The operating (resonant) frequency of antenna  40  may be selected by adjusting the dimensions of dielectric resonating element  92  (e.g., in the direction of the X, Y, and/or Z axes of  FIG.  6   ). Dielectric resonating element  92  may be formed from a column of dielectric material having dielectric constant do. Dielectric constant d k3  may be relatively high (e.g., greater than 10.0, greater than 12.0, greater than 15.0, greater than 20.0, between 15.0 and 40.0, between 10.0 and 50.0, between 18.0 and 30.0, between 12.0 and 45.0, etc.). In one suitable arrangement, dielectric resonating element  92  may be formed from zirconia or a ceramic material. Other dielectric materials may be used to form dielectric resonating element  92  if desired. 
     Dielectric substrate  90  may be formed from a material having dielectric constant d k4 . Dielectric constant d k4  may be less than dielectric constant do of dielectric resonating element  92  (e.g., less than 18.0, less than 15.0, less than 10.0, between 3.0 and 4.0, less than 5.0, between 2.0 and 5.0, etc.). Dielectric constant d k4  may be less than dielectric constant do by at least 10.0, 5.0, 15.0, 12.0, 6.0, etc. In one suitable arrangement, dielectric substrate  90  may be formed from molded plastic (e.g., injection molded plastic). Other dielectric materials may be used to form dielectric substrate  90  or dielectric substrate  90  may be omitted if desired. The difference in dielectric constant between dielectric resonating element  92  and dielectric substrate  90  may establish a radio-frequency boundary condition between dielectric resonating element  92  and dielectric substrate  90  from bottom surface  100  to top surface  98 . This may configure dielectric resonating element  92  to serve as a waveguide for propagating radio-frequency signals at millimeter and centimeter wave frequencies. 
     Dielectric substrate  90  may have a width (thickness)  106  on each side of dielectric resonating element  92 . Width  106  may be selected to isolate dielectric resonating element  92  from peripheral conductive housing structures  12 W and to minimize signal reflections in dielectric substrate  90 . Width  106  may be, for example, at least one-tenth of the effective wavelength of the radio-frequency signals in a dielectric material of dielectric constant d k4 . Width  106  may be 0.4-0.5 mm, 0.3-0.5 mm, 0.2-0.6 mm, greater than 0.1 mm, greater than 0.3 mm, 0.2-2.0 mm, 0.3-1.0 mm, or greater than between 0.4 and 0.5 mm, as examples. 
     Dielectric resonating element  92  may radiate radio-frequency signals  104  when excited by the signal conductor for radio-frequency transmission line  74 . In some scenarios, a slot is formed in ground traces on top surface  76  of flexible printed circuit, the slot is indirectly fed by a signal conductor embedded within flexible printed circuit  72 , and the slot excites dielectric resonating element  92  to radiate radio-frequency signals  104 . However, in these scenarios, the radiating characteristics of the antenna may be affected by how the dielectric resonating element is mounted to flexible printed circuit  72 . For example, air gaps or layers of adhesive used to mount the dielectric resonating element to the flexible printed circuit can be difficult to control and can undesirably affect the radiating characteristics of the antenna. In order to mitigate the issues associated with exciting dielectric resonating element  92  using an underlying slot, antenna  40  may be fed using a radio-frequency feed probe such as feed probe  85 . Feed probe  85  may form part of the antenna feed for antenna  40  (e.g., antenna feed  44  of  FIG.  3   ). 
     As shown in  FIG.  6   , feed probe  85  may be formed from conductive traces  84 . Conductive traces  84  may include a first portion patterned onto a given sidewall  102  of dielectric resonating element  92  (e.g., a conductive patch on sidewall  102  formed using a sputtering process or other conductive deposition techniques). Conductive traces  84  may include a second portion coupled to signal traces  82  using conductive interconnect structures  86 . Conductive interconnect structures  86  may include solder, welds, conductive adhesive, conductive tape, conductive foam, conductive springs, conductive brackets, and/or any other desired conductive interconnect structures. Feed probe  85  may be formed from any desired conductive structures (e.g., conductive traces, conductive foil, sheet metal, and/or other conductive structures). 
     Signal traces  82  may convey radio-frequency signals to and from feed probe  85 . Feed probe  85  may electromagnetically couple the radio-frequency signals on signal traces  82  into dielectric resonating element  92 . This may serve to excite one or more electromagnetic modes (e.g., radio-frequency cavity or waveguide modes) of dielectric resonating element  92 . When excited by feed probe  85 , the electromagnetic modes of dielectric resonating element  92  may configure the dielectric resonating element to serve as a waveguide that propagates the wavefronts of radio-frequency signals  104  along the length of dielectric resonating element  92  (e.g., in the direction of the Z-axis of  FIG.  6   ), through top surface  98 , and through display  14 . 
     For example, during signal transmission, radio-frequency transmission line  74  may supply radio-frequency signals from the millimeter/centimeter wave transceiver circuitry to antenna  40 . Feed probe  85  may couple the radio-frequency signals on signal traces  82  into dielectric resonating element  92 . This may serve to excite one or more electromagnetic modes of dielectric resonating element  92 , resulting in the propagation of radio-frequency signals  104  up the length of dielectric resonating element  92  and to the exterior of device  10  through display cover layer  56 . Similarly, during signal reception, radio-frequency signals  104  may be received through display cover layer  56 . The received radio-frequency signals may excite the electromagnetic modes of dielectric resonating element  92 , resulting in the propagation of the radio-frequency signals down the length of dielectric resonating element  92 . Feed probe  85  may couple the received radio-frequency signals onto radio-frequency transmission line  74 , which passes the radio-frequency signals to the millimeter/centimeter wave transceiver circuitry. The relatively large difference in dielectric constant between dielectric resonating element  92  and dielectric substrate  90  may allow dielectric resonating element  92  to convey radio-frequency signals  104  with a relatively high antenna efficiency (e.g., by establishing a strong boundary between dielectric resonating element  92  and dielectric substrate  90  for the radio-frequency signals). The relatively high dielectric constant of dielectric resonating element  92  may also allow the dielectric resonating element  92  to occupy a relatively small volume compared to scenarios where materials with a lower dielectric constant are used. 
     The dimensions of feed probe  85  (e.g., in the direction of the X-axis and Z-axis of  FIG.  6   ) may be selected to help match the impedance of radio-frequency transmission line  74  to the impedance of dielectric resonating element  92 . Feed probe  85  may be located on a particular sidewall  102  of dielectric resonating element  92  to provide antenna  40  with a desired linear polarization (e.g., a vertical or horizontal polarization). If desired, multiple feed probes  85  may be formed on multiple sidewalls  102  of dielectric resonating element  92  to configure antenna  40  to cover multiple orthogonal linear polarizations at once. The phase of each feed probe may be independently adjusted over time to provide the antenna with other polarizations such as an elliptical or circular polarization if desired. Feed probe  85  may sometimes be referred to herein as feed conductor  85 , feed patch  85 , or probe feed  85 . Dielectric resonating element  92  may sometimes be referred to herein as a dielectric radiating element, dielectric radiator, dielectric resonator, dielectric antenna resonating element, dielectric column, dielectric pillar, radiating element, or resonating element. When fed by one or more feed probes such as feed probe  85 , dielectric resonator antennas such as antenna  40  of  FIG.  6    may sometimes be referred to herein as probe-fed dielectric resonator antennas. 
     Display cover layer  56  may be formed from a dielectric material having dielectric constant d k1  that is less than dielectric constant do. For example, dielectric constant may be between about 3.0 and 10.0 (e.g., between 4.0 and 9.0, between 5.0 and 8.0, between 5.5 and 7.0, between 5.0 and 7.0, etc.). In one suitable arrangement, display cover layer  56  may be formed from glass, plastic, or sapphire. If care is not taken, the relatively large difference in dielectric constant between display cover layer  56  and dielectric resonating element  92  may cause undesirable signal reflections at the boundary between the display cover layer and the dielectric resonating element. These reflections may result in destructive interference between the transmitted and reflected signals and in stray signal loss that undesirably limits the antenna efficiency of antenna  40 . 
     In order to mitigate effects, antenna  40  may be provided with an impedance matching layer such as dielectric matching layer  94 . Dielectric matching layer  94  may be mounted to top surface  98  of dielectric resonating element  92  between dielectric resonating element  92  and display cover layer  56 . If desired, dielectric matching layer  94  may be adhered to dielectric resonating element  92  using a layer of adhesive  96 . Adhesive may also or alternatively be used to adhere dielectric matching layer  94  to display cover layer  56  if desired. Adhesive  96  may be relatively thin so as not to significantly affect the propagation of radio-frequency signals  104 . 
     Dielectric matching layer  94  may be formed from a dielectric material having dielectric constant d k2 . Dielectric constant d k2  may be greater than dielectric constant dki and less than dielectric constant d k3 . As an example, dielectric constant d k2  may be equal to SQRT(d k1 *d k3 ), where SQRT( ) is the square root operator and “*” is the multiplication operator. The presence of dielectric matching layer  94  may allow radio-frequency signals to propagate without facing a sharp boundary between the material of dielectric constant d k1  and the material of dielectric constant d k3 , thereby helping to reduce signal reflections. 
     Dielectric matching layer  94  may be provided with thickness  88 . Thickness  88  may be selected to be approximately equal to (e.g., within 15% of) one-quarter of the effective wavelength of radio-frequency signals  104  in dielectric matching layer  94 . The effective wavelength is given by dividing the free space wavelength of radio-frequency signals  104  (e.g., a centimeter or millimeter wavelength corresponding to a frequency between 10 GHz and 300 GHz) by a constant factor (e.g., the square root of d k3 ). When provided with thickness  88 , dielectric matching layer  94  may form a quarter wave impedance transformer that mitigates any destructive interference associated with the reflection of radio-frequency signals  104  at the boundaries between display cover layer  56 , dielectric matching layer  94 , and dielectric resonating element  92 . 
     When configured in this way, antenna  40  may radiate radio-frequency signals  104  through the front face of device  10  despite being coupled to the millimeter/centimeter wave transceiver circuitry over a flexible printed circuit located at the rear of device  10 . The relatively narrow width of dielectric resonating element  92  may allow antenna  40  to fit in the volume between display module  68 , other components  58 , and peripheral conductive housing structures  12 W. Antenna  40  of  FIG.  6    may be formed in a front-facing phased antenna array that conveys radio-frequency signals across at least a portion of the hemisphere above the front face of device  10 . 
       FIG.  7    is a perspective view of the probe-fed dielectric resonator antenna of  FIG.  6    in a scenario where the dielectric resonating element is fed using multiple feed probes for covering multiple polarizations. Peripheral conductive housing structures  12 W, dielectric substrate  90 , dielectric matching layer  94 , adhesive  96 , rear housing wall  12 R, display  14 , and other components  58  of  FIG.  6    are omitted from  FIG.  7    for the sake of clarity. 
     As shown in  FIG.  7   , dielectric resonating element  92  of antenna  40  is mounted to top surface  76  of flexible printed circuit  72 . Antenna  40  may be fed using multiple feed probes  85  such as a first feed probe  85 V and a second feed probe  85 H mounted to dielectric resonating element  92  and flexible printed circuit  72 . Feed probe  85 V includes conductive traces  84 V patterned on a first sidewall  102  of dielectric resonating element  92 . Feed probe  85 H includes conductive traces  84 H patterned on a second (orthogonal) sidewall  102  of dielectric resonating element  92 . 
     Antenna  40  may be fed using multiple radio-frequency transmission lines  74  such as a first radio-frequency transmission line  74 V and a second radio-frequency transmission line  74 H. First radio-frequency transmission line  74 V may include conductive traces  122 V and  120 V on top surface  76  of flexible printed circuit  72 . Conductive traces  122 V and  120 V may form part of the signal conductor (e.g., signal traces  82  of  FIG.  6   ) for radio-frequency transmission line  74 V. Similarly, second radio-frequency transmission line  74 H may include conductive traces  122 H and  120 H on top surface  76  of flexible printed circuit  72 . Conductive traces  122 H and  120 H may form part of the signal conductor (e.g., signal traces  82  of  FIG.  6   ) for radio-frequency transmission line  74 H. 
     Conductive trace  122 V may be narrower than conductive trace  120 V. Conductive trace  122 H may be narrower than conductive trace  120 H. Conductive traces  120 V and  120 H may, for example, be conductive contact pads on top surface  76  of flexible printed circuit  72 . Conductive traces  84 V of feed probe  85 V may be mounted and coupled to conductive trace  120 V (e.g., using conductive interconnect structures  86  of  FIG.  6   ). Similarly, conductive traces  84 H of feed probe  85 H may be mounted and coupled to conductive trace  120 H. 
     Radio-frequency transmission line  74 V and feed probe  85 V may convey first radio-frequency signals having a first linear polarization (e.g., a vertical polarization). When driven using the first radio-frequency signals, feed probe  85 V may excite one or more electromagnetic modes of dielectric resonating element  92  associated with the first polarization. When excited in this way, wave fronts associated with the first radio-frequency signals may propagate along the length of dielectric resonating element  92  (e.g., along central/longitudinal axis  109 ) and may be radiated through the display (e.g., through display cover layer  56  of  FIG.  6   ). 
     Similarly, radio-frequency transmission line  74 H and feed probe  85 H may convey radio-frequency signals of a second linear polarization orthogonal to the first polarization (e.g., a horizontal polarization). When driven using the second radio-frequency signals, feed probe  85 H may excite one or more electromagnetic modes of dielectric resonating element  92  associated with the second polarization. When excited in this way, wave fronts associated with the second radio-frequency signals may propagate along the length of dielectric resonating element  92  and may be radiated through the display (e.g., through display cover layer  56  of  FIG.  6   ). Both feed probes  85 H and  85 V may be active at once so that antenna  40  conveys both the first and second radio-frequency signals at any given time. In another suitable arrangement, a single one of feed probes  85 H and  85 V may be active at once so that antenna  40  conveys radio-frequency signals of only a single polarization at any given time. 
     Dielectric resonating element  92  may have a length  110 , width  112 , and height  114 . Length  110 , width  112 , and height  114  may be selected to provide dielectric resonating element  92  with a corresponding mix of electromagnetic cavity/waveguide modes that, when excited by feed probes  85 H and/or  85 V, configure antenna  40  to radiate at desired frequencies. For example, height  114  may be 2-10 mm, 4-6 mm, 3-7 mm, 4.5-5.5 mm, or greater than 2 mm. Width  112  and length  110  may each be 0.5-1.0 mm, 0.4-1.2 mm, 0.7-0.9 mm, 0.5-2.0 mm, 1.5 mm-2.5 mm, 1.7 mm-1.9 mm, 1.0 mm-3.0 mm, etc. Width  112  may be equal to length  110  or, in other arrangements, may be different than length  110 . Sidewalls  102  of dielectric resonating element  92  may contact the surrounding dielectric substrate (e.g., dielectric substrate  90  of  FIG.  6   ). The dielectric substrate may be molded over feed probes  85 H and  85 V or may include openings, notches, or other structures that accommodate the presence of feed probes  85 H and  85 V. The example of  FIG.  7    is merely illustrative and, if desired, dielectric resonating element  92  may have other shapes (e.g., shapes with any desired number of straight and/or curved sidewalls  102 ). 
     Conductive traces  84 V and  84 H may each have width  118  and height  116 . Width  118  and height  116  may be selected to match the impedance of radio-frequency transmission lines  74 V and  74 H to the impedance of dielectric resonating element  92 . As an example, width  118  may be between 0.3 mm and 0.7 mm, between 0.2 mm and 0.8 mm, between 0.4 mm and 0.6 mm, or other values. Height  116  may be between 0.3 mm and 0.7 mm, between 0.2 mm and 0.8 mm, between 0.4 mm and 0.6 mm, or other values. Height  116  may be equal to width  118  or may be different than width  118 . 
     If desired, transmission lines  74 V and  74 H may include one or more transmission line matching stubs such as matching stubs  124  coupled to traces  122 V and  122 H. Matching stubs  124  may help to ensure that the impedance of radio-frequency transmission lines  74 H and  74 V are matched to the impedance of dielectric resonating element  92 . Matching stubs  124  may have any desired shape or may be omitted. Conductive traces  84 V and  84 H may have other shapes (e.g., shapes having any desired number of straight and/or curved edges). 
     If desired, a slot may be formed in ground traces  80  on flexible printed circuit  72  to help match the impedance of the radio-frequency transmission line(s) to dielectric resonating element  92 .  FIG.  8    is a cross-sectional side view of antenna  40  showing how ground traces  80  may include an opening to help match the impedance of the radio-frequency transmission line(s) to dielectric resonating element  92 . In the example of  FIG.  8   , only a single feed probe is shown and peripheral conductive housing structures  12 W, dielectric substrate  90 , dielectric matching layer  94 , adhesive  96 , rear housing wall  12 R, display  14 , and other components  58  of  FIG.  6    are omitted for the sake of clarity. 
     As shown in  FIG.  8   , ground traces  80  may include a slot or opening such as slot  126  at bottom surface  78  of flexible printed circuit  72 . Dielectric resonating element  92  of antenna  40  may be mounted to flexible printed circuit  72  and may be aligned with the underlying slot  126 . Slot  126  may have a width  128 . Width  128  may, for example, be greater than or equal to width  112  of dielectric resonating element  92  (e.g., an entirety of the lateral area of dielectric resonating element  92  may overlap slot  126 ). Slot  126  may help to match the impedance of transmission line  74  to the impedance of dielectric resonating element  92 . If desired, the presence of slot  126  may also allow feed probe  85  to excite additional electromagnetic modes of dielectric resonating element  92  to expand the frequencies and/or bandwidth covered by antenna  40 . Width  128  may be adjusted to optimize impedance matching between radio-frequency transmission line  74  and dielectric resonating element  92  and/or to tune the frequency response (e.g., peak response frequency and bandwidth) of antenna  40 . In addition, slot  126  may serve to minimize coupling between two linear polarizations (e.g., horizontal and vertical polarizations) in dielectric resonating element  92 . For example, slot  126  may help to disturb ground current flow between the transceiver ports associated with transmission lines  74 V and  74 H ( FIG.  7   ). 
       FIG.  9    is a top-down view of antenna  40  showing how dielectric resonating element  92  may overlap an underlying slot  126  in ground traces  80  (e.g., as taken in the direction of arrow  130  of  FIG.  8   ). In the example of  FIG.  9   , the dielectric material in flexible printed circuit  72  of  FIG.  8    has been omitted for the sake of clarity. 
     As shown in  FIG.  9   , dielectric resonating element  92  may be aligned with slot  126  in the underlying ground traces  80 . Slot  126  may have a rectangular shape (e.g., the same shape as the lateral shape of dielectric resonating element  92 ) or may have other shapes. Signal traces  82  may be coupled to conductive traces  84  in a corresponding feed probe  85  located on a given sidewall of dielectric resonating element  92 . This example is merely illustrative and, if desired, additional feed probes and radio-frequency transmission lines may be provided to cover additional polarizations. 
     In practice, if care is not taken, dielectric resonator antennas such as antenna  40  can be subject to undesirable cross-polarization interference. Cross-polarization interference can occur when radio-frequency signals to be conveyed in a first polarization are undesirably transmitted or received using an antenna feed that is used to convey radio-frequency signals in a second polarization. For example, cross-polarization interference may involve the leakage of horizontally-polarized signals onto feed probe  85 V of  FIG.  7    (e.g., a feed probe intended to convey vertically-polarized signals) and/or the leakage of vertically-polarized signals onto feed probe  85 H of  FIG.  7    (e.g., a feed probe intended to convey horizontally-polarized signals). The cross-polarization interference can arise when the electric field produced by feed probe  85 V has components oriented at a mix of different angles or when the electric field produced by feed probe  85 H has components oriented at a mix of different angles within dielectric resonating element  92 . Cross-polarization interference can lead to a decrease in overall data throughput, errors in the transmitted or received data, or otherwise degraded antenna performance. These effects are also particularly detrimental in scenarios where antenna  40  conveys independent data streams using horizontal and vertical polarizations (e.g., under a MIMO scheme), as the cross-polarization interference reduces the independence of the data streams. It would therefore be desirable to be able to provide a dielectric resonator antenna such as antenna  40  with structures for mitigating cross polarization interference (e.g., for maximizing isolation between polarizations handled by the antenna). 
       FIG.  10    is a top-down view of antenna  40  having structures for mitigating cross polarization interference. In the example of  FIG.  10   , antenna  40  is a dual-polarization dielectric resonator antenna having feed probes  85 V and  85 H for exciting different polarizations of dielectric resonating element  92 . 
     As shown in  FIG.  10   , dielectric resonating element  92  may have a rectangular lateral profile. Dielectric resonating element  92  may have four sidewalls  102  (e.g., four vertical faces or surfaces) such as a first sidewall  102 A, a second sidewall  102 B, a third sidewall  102 C, and a fourth sidewall  102 D. Third sidewall  102 C may oppose first sidewall  102 A and fourth sidewall  102 D may oppose second sidewall  102 B on dielectric resonating element  92 . Conductive traces  84 V of feed probe  85 V may be patterned onto first sidewall  102 A. Conductive traces  84 V may also be coupled to conductive trace  120 V on the underlying flexible printed circuit  72 . Conductive trace  122 V may be coupled to conductive trace  120 V. Similarly, conductive traces  84 H of feed probe  85 H may be patterned onto second sidewall  102 B. Conductive traces  84 V may also be coupled to conductive trace  120 H on flexible printed circuit  72 . Conductive trace  122 H may be coupled to conductive trace  120 H. 
     In order to mitigate cross polarization interference, parasitic elements such as parasitic elements  132 H and  132 V may be patterned onto the sidewalls of dielectric resonating element  92 . Parasitic elements  132 H and  132 V may, for example, be formed from floating patches of conductive material patterned onto the sidewalls of dielectric resonating element  92  (e.g., conductive patches that are not coupled to ground or the signal traces for antenna  40 ). As shown in  FIG.  10   , parasitic element  132 H may be patterned onto fourth sidewall  102 D opposite feed probe  85 H. Parasitic element  132 V may be patterned onto third sidewall  102 C opposite first feed probe  85 V. 
     The presence of the conductive material in parasitic element  132 H may serve to change the boundary condition for the electric field excited by feed probe  85 H within dielectric resonating element  92 . For example, in scenarios where parasitic element  132 H is omitted, the electric field excited by feed probe  85 H may include a mix of different electric field components oriented in different directions. This may lead to cross-polarization interference in which some vertically-polarized signals undesirably leak onto feed probe  85 H. However, the boundary condition created by parasitic element  132 H may serve to align the electric field excited by feed probe  85 H in a single direction between sidewalls  102 B and  102 D, as shown by arrows  131  (e.g., in a horizontal direction parallel to the X-axis). Because the entire electric field excited by feed probe  85 H is horizontal, feed probe  85 H may only convey horizontally-polarized signals without vertically-polarized signals interfering with the horizontally-polarized signals. 
     Similarly, the presence of the conductive material in parasitic element  132 V may serve to change the boundary condition for the electric field excited by feed probe  85 V within dielectric resonating element  92 . For example, in scenarios where parasitic element  132 V is omitted, the electric field excited by feed probe  85 V may include a mix of different electric field components oriented in different directions. This may lead to cross-polarization interference in which some horizontally-polarized signals undesirably leak onto feed probe  85 V. However, the boundary condition created by parasitic element  132 V may serve to align the electric field excited by feed probe  85 V in a single direction between sidewalls  102 A and  102 C, as shown by arrows  133  (e.g., in a vertical direction parallel to the Y-axis). Because the entire electric field excited by feed probe  85 V is vertical, feed probe  85 V may only convey vertically-polarized signals without horizontally-polarized signals interfering with the vertically-polarized signals. 
     Parasitic element  132 V may have a shape (e.g., lateral dimensions in the X-Z plane) that matches the shape of the portion of conductive traces  84 V on sidewall  102 A (e.g., parasitic element  132 V may have width  118  and height  116  of  FIG.  7   . Similarly, parasitic element  132 H may have a shape (e.g., lateral dimensions in the Y-Z plane) that matches the shape of the portion of conductive traces  84 H on sidewall  102 B (e.g., parasitic element  132 H may have width  118  and height  116  of  FIG.  7   ). This may ensure that there are symmetric boundary conditions between feed probe  85 V and parasitic element  132 V and between feed probe  85 H and parasitic element  132 H. Parasitic element  132 V need not have the same exact dimensions as feed probe  85 V and parasitic element  132 H need not have the same exact dimensions as feed probe  85 H if desired. 
       FIG.  11    is a cross-sectional side view of antenna  40  having parasitic elements  132 H and  132 V (e.g., as taken along line AA′ of  FIG.  10   ). As shown in  FIG.  11   , conductive traces  84 H of feed probe  85 H may be coupled to trace  120 H using conductive interconnect structures  86  (e.g., solder). Parasitic element  132 H may be formed on sidewall  102 D of dielectric resonating element  92  opposite feed probe  85 H. Parasitic element  132 H may have the same dimensions as the portion of conductive traces  84 H patterned onto sidewall  102 B of dielectric resonating element  92 . Parasitic element  132 H may extend downward to top surface  76  of flexible printed circuit  72  if desired. Parasitic element  132 H is not coupled to signal traces for antenna  40  or ground traces for antenna  40  (e.g., parasitic element  132 H is a floating parasitic patch on sidewall  102 D). If desired, parasitic element  132 H may be soldered to floating traces on top surface  76  of flexible printed circuit  72  (e.g., to help provide mechanical support for parasitic element  132 H). Similar structures may be used to form parasitic element  132 V on sidewall  102 C of  FIG.  10   . 
     Parasitic element  132 H may be aligned with and overlapping (e.g., completely overlapping) the lateral area of feed probe  85 H in the Y-Z plane. Similarly, parasitic element  132 V may be aligned with and overlapping (e.g., completely overlapping) the lateral area of feed probe  85 V in the X-Z plane ( FIG.  10   ). Parasitic elements  132 H and  132 V may serve to mitigate cross-polarization interference for relatively low frequencies such as frequencies from about 24 GHz to about 30 GHz. However, if care is not taken, cross-polarization interference may still occur at higher frequencies such as frequencies from about 37 GHz to about 43 GHz. In order to mitigate cross-polarization at higher frequencies, antenna  40  may include additional parasitic patches on other portions of dielectric resonating element  92 . 
     As shown in  FIG.  11   , dielectric resonating element  92  may have a top end (portion)  136  at top surface  98  (e.g., the end of dielectric resonating element  92  opposing feed probe  85 H and flexible printed circuit  72 ). Antenna  40  may include one or more parasitic elements  134  patterned onto one or more sidewalls of dielectric resonating element  92  at end  136 . For example, antenna  40  may include a first parasitic element  134 D patterned onto sidewall  102 D at end  136  and/or a second parasitic element  134 B patterned onto sidewall  102 B. Parasitic elements  134 D and  134 B may be floating conductive patches that are not coupled to signal traces or ground traces for antenna  40 . Parasitic element  134 D may be aligned with and overlapping (e.g., completely overlapping) parasitic element  134 B. Parasitic element  134 D may have the same shape and size as parasitic element  134 B, if desired. Parasitic elements  134 D and  134 B may serve to create additional electromagnetic boundary conditions for dielectric resonating element  92 . These boundary conditions may serve to align the electric field excited by feed probe  85 H at relatively high frequencies, such as frequencies from about 37 GHz to about 43 GHz, in a single direction between sidewalls  102 D and  102 B (e.g., in a horizontal direction parallel to the X-axis). This may serve to mitigate cross-polarization interference for feed probe  85 H at these relatively high frequencies. 
     The example of  FIG.  11    is merely illustrative. In another suitable arrangement, parasitic elements  134 D and  134 B may be patterned onto portions of sidewalls  102 D and  102 B that are interposed between end  136  and feed probe  85 H (e.g., parasitic elements  134 D and  134 B need not be formed at end  136  of dielectric resonating element  92 ). When similar parasitic elements  134  are patterned onto dielectric resonating element  92  for mitigating cross-polarization interference on feed probe  85 V of  FIG.  10   , antenna  40  may include a total of six parasitic elements.  FIG.  12    is a perspective view showing how antenna  40  may include six parasitic elements. 
     In the example of  FIG.  12   , feed probes  85 H and  85 V have been omitted for the sake of clarity. Dielectric resonating element  92  of  FIG.  12    is shown in transparency for the sake of illustration. As shown in  FIG.  12   , antenna  40  may include parasitic element  132 H on sidewall  102 D at the end of dielectric resonating element  92  opposite top surface  98 . Antenna  40  may include parasitic element  132 V on sidewall  102 C at the end of dielectric resonating element  92  opposite top surface  98 . Antenna  40  may also include a parasitic element  134 A patterned onto sidewall  102 A at end  136  of dielectric resonating element  92  and may include a parasitic element  134 C patterned onto sidewall  102 C at end  136  of dielectric resonating element  92 . 
     Parasitic elements  134 A and  134 C may be floating conductive patches that are not coupled to signal traces or ground traces for antenna  40 . Parasitic element  134 C may be aligned with and overlapping (e.g., completely overlapping) parasitic element  134 A. Parasitic element  134 C may have the same shape and size as parasitic element  134 A, if desired. Parasitic elements  134 C and  134 A may serve to create additional electromagnetic boundary conditions for dielectric resonating element  92 . These boundary conditions may serve to align the electric field excited by feed probe  85 V ( FIG.  10   ) at relatively high frequencies such as frequencies from about 37 GHz to about 43 GHz in a single direction between sidewalls  102 A and  102 C (e.g., in a vertical direction parallel to the Y-axis). This may serve to mitigate cross-polarization interference for feed probe  85 V ( FIG.  10   ) at these relatively high frequencies. 
     The example of  FIG.  12    is merely illustrative. If desired, additional parasitic elements may be patterned onto any desired portions of sidewalls  102  (e.g., antenna  40  may include more than six parasitic elements). Parasitic elements  132 H,  132 V,  134 A,  134 B,  134 C, and/or  134 D may be omitted if desired. The parasitic elements may collectively serve to isolate antenna  40  from cross-polarization interference at any desired frequencies. 
     Antenna  40  may also include cross-polarization interference mitigating parasitic elements in scenarios where antenna  40  is fed using only a single feed probe.  FIG.  13    is a top-down view showing how antenna  40  may include cross-polarization interference mitigating parasitic elements in an arrangement where antenna  40  is fed using only a single feed probe  85 . 
     As shown in  FIG.  13   , antenna  40  may be fed using a single feed probe  85 . Conductive traces  84  of feed probe  85  may be patterned onto sidewall  102 A of dielectric resonating element  92 . Conductive traces  84  may be coupled to signal traces  82  on the underlying flexible printed circuit  72 . Ground traces such as ground traces  140  may also be patterned onto flexible printed circuit  72 . 
     Antenna  40  may include one or more parasitic elements  138  such as a first parasitic element  138 - 1  and a second parasitic element  138 - 2 . Parasitic element  138 - 1  may be formed from a patch of conductive traces (e.g., a conductive patch) that is patterned onto sidewall  102 D of dielectric resonating element  92 . Parasitic element  138 - 2  may be formed from a patch of conductive traces (e.g., a conductive patch) that is patterned onto sidewall  102 B of dielectric resonating element  92 . Parasitic elements  138 - 1  and  138 - 2  may each have the same size and lateral dimensions (e.g., in the Y-Z plane) as conductive traces  84  (e.g., in the X-Z plane), for example. Parasitic element  138 - 1  and parasitic element  138 - 2  may each be coupled to ground traces  140  at flexible printed circuit  72  by conductive interconnect structures  142 . Conductive interconnect structures  142  may include solder, welds, conductive adhesive, conductive tape, conductive foam, conductive springs, conductive brackets, and/or any other desired conductive interconnect structures. In this way, parasitic elements  138 - 1  and  138 - 2  may each be held at a ground potential (e.g., parasitic elements  138 - 1  and  138 - 2  may be grounded patches). Parasitic element  138 - 1  may be omitted or parasitic element  138 - 2  may be omitted if desired (e.g., antenna  40  may include only a single parasitic element  138  if desired). 
     Parasitic element  138 - 1  and/or parasitic element  138 - 2  may serve to alter the electromagnetic boundary conditions of dielectric resonating element  92  to mitigate cross-polarization interference for feed probe  85  (e.g., to isolate feed probe  85  from interference from horizontally-polarized signals in scenarios where feed probe  85  handles vertically-polarized signals). Sidewall  102 C of dielectric resonating element  92  may be free from conductive material such as parasitic elements  138 . 
       FIG.  14    is a side view of antenna  40  of  FIG.  13    (e.g., as taken in the direction of arrow  143  of  FIG.  13   ). As shown in  FIG.  14   , ground traces  140  may be patterned onto top surface  76  of flexible printed circuit  72 . Ground traces  140  may be coupled to other grounded structures in device  10 . For example, ground traces  140  may be coupled to ground traces  80  of  FIGS.  6 - 8    using conductive vias  145  that extend through flexible printed circuit  72 . Ground traces  140  may have lateral openings to accommodate signal traces  82  of  FIG.  13    if desired. Parasitic element  138 - 1  may be formed from a patch of conductive traces patterned onto sidewall  102 D whereas parasitic element  138 - 2  is formed from a patch of conductive traces patterned onto sidewall  102 B. Parasitic elements  138 - 1  and  138 - 2  may be coupled to the underlying ground traces  140 . Parasitic elements  138 - 1  and  138 - 2  are located at the end of dielectric resonating element  92  opposite to top surface  98  (e.g., the end of dielectric resonating element  92  at flexible printed circuit  72 ). If desired, the single-polarization antenna  40  of  FIGS.  13  and  14    may include additional parasitic elements (e.g., at the end of dielectric resonating element  92  at top surface  98 ) such as parasitic elements  134 A- 134 D of  FIG.  12   . 
       FIG.  15    is a plot of antenna performance (return loss) as a function of frequency for the single-polarization antenna  40  of  FIGS.  13  and  14   . Curve  144  of  FIG.  15    plots the response of antenna  40  in the absence of parasitic elements  138 - 1  and  138 - 2 . As shown by curve  144 , antenna  40  exhibits a relatively narrow response peak within the frequency band of operation of dielectric resonating element  92  (e.g., a frequency band B extending from frequency F 1  to frequency F 2 ). Frequency F 1  may be about 26 GHz whereas frequency F 2  is about 30 GHz, as just one example. The narrow response peak of curve  144  may be insufficient to satisfactorily cover an entirety of frequency band B from frequency F 1  to frequency F 2 . 
     Curve  146  of  FIG.  15    plots the response of an antenna  40  in an example where antenna  40  includes only one of parasitic elements  138 - 1  and  138 - 2 . As shown by curve  146 , the presence of a single parasitic element  138  may serve to improve the response of antenna  40  at the lower end of frequency band B (e.g., at frequencies near frequency F 1 ) and at the upper end of frequency band B (e.g., at frequencies near frequency F 2 ) relative to scenarios where no parasitic elements are used. 
     Curve  148  of  FIG.  15    plots the response of antenna  40  in an example where antenna  40  includes both parasitic elements  138 - 1  and  138 - 2 . As shown by curve  148 , the presence of both parasitic elements  138 - 1  and  138 - 2  may serve to improve the response of antenna  40  across most of frequency band B relative to scenarios where no parasitic elements are used. In addition, the presence of both parasitic elements  138 - 1  and  138 - 2  may serve to improve the response of antenna  40  near the center of frequency band B relative to scenarios where only one parasitic element  138  is used. The example of  FIG.  15    is merely illustrative. Curves  144 ,  146 , and  148  may have other shapes. Frequency band B may include any desired millimeter and/or centimeter wave frequencies. 
     One or more front-facing phased antenna arrays  54 - 2  (e.g., phased antenna arrays including the dual-polarization antenna  40  of  FIGS.  10 - 12    and/or the single-polarization antenna  40  of  FIGS.  13  and  14   ) may be mounted at any desired locations in device  10  along the periphery of display  14  for radiating through the display (e.g., within inactive area IA of display  14  of  FIG.  1   ).  FIG.  16    is a top-down view of device  10  showing how a given phased antenna array  54 - 2  may be aligned with a notch in peripheral conductive housing structures  12 W. 
     As shown in  FIG.  16   , peripheral conductive housing structures  12 W may run around the periphery of display module  68  in device  10 . Display cover layer  56  of  FIGS.  5  and  6    has been omitted from  FIG.  16    for the sake of clarity. Peripheral conductive housing structures  12 W may include an inwardly protruding lip  149  (sometimes referred to herein as a ledge or datum) and a raised portion  151 . Raised portion  151  may run around the peripheral edge of the display cover layer. Lip  149  of peripheral conductive housing structures  12 W may include an opening such as notch  150 . Phased antenna array  54 - 2  (e.g., a phased antenna array that covers a single polarization and frequency band, a phased antenna array that covers multiple polarizations in the same frequency band(s), a phased antenna array that covers multiple polarizations and multiple frequency bands, or a phased antenna array that covers a single polarization and multiple frequency bands) may be mounted below lip  149  and aligned with notch  150 . 
     The antennas  40  in phased antenna array  54 - 2  may each include a dielectric resonating element  92  surrounded by one or more dielectric substrates  90 . Each antenna  40  in phased antenna array  54 - 2  may be fed using a corresponding radio-frequency transmission line in the same flexible printed circuit  72 . This example is merely illustrative and, if desired, two or more antennas  40  in phased antenna array  54 - 2  may be fed using radio-frequency transmission lines in separate flexible printed circuits. The antennas  40  in phased antenna array  54 - 2  may convey radio-frequency signals through notch  150  and the display cover layer (not shown). Phased antenna array  54 - 2  may perform beam steering within the hemisphere above the front face of device  10 . The example of  FIG.  16    is merely illustrative. If desired, the antennas  40  in phased antenna array  54 - 2  may be arranged in a two-dimensional pattern having multiple rows and columns of antennas or in may be arranged in other patterns. 
     If desired, phased antenna array  54 - 2  may be located elsewhere within device  10 . In one suitable arrangement, phased antenna array  54 - 2  may be located within notch  8  in active area AA of display  14  ( FIG.  1   ).  FIG.  17    is a top-down view showing how phased antenna array  54 - 2  may be aligned with notch  8  in active area AA of display  14 . 
     As shown in  FIG.  17   , display module  68  of display  14  may include notch  8 . Display cover layer  56  of  FIGS.  5  and  6    has been omitted from  FIG.  17    for the sake of clarity. Display module  68  may form active area AA of display  14  whereas notch  8  forms part of inactive area IA of display  14  ( FIG.  1   ). The edges of notch  8  may be defined by peripheral conductive housing structures  12 W and display module  68 . For example, notch  8  may have two or more edges (e.g., three edges) defined by display module  68  and one or more edges defined by peripheral conductive housing structures  12 W. 
     Device  10  may include speaker port  16  (e.g., an ear speaker) within notch  8 . If desired, device  10  may include other components  152  within notch  10 . Other components  152  may include one or more image sensors such as one or more cameras, an infrared image sensor, an infrared light emitter (e.g., an infrared dot projector and/or flood illuminator), an ambient light sensor, a fingerprint sensor, a capacitive proximity sensor, a thermal sensor, a moisture sensor, or any other desired input/output components (e.g., input/output devices  26  of  FIG.  2   ). One or more phased antenna arrays  54 - 2  may be aligned with the portion(s) of notch  8  that are not occupied by other components  152  or speaker port  16 . Phased antenna arrays  54 - 2  that are aligned with notch  8  may include one-dimensional phased antenna arrays such as one-dimensional phased antenna array  54 - 2 ′ and/or two-dimensional phased antenna arrays such as two-dimensional phased antenna array  54 - 2 ″. Because dielectric resonating elements  92  occupy less lateral area than patch antennas or slot antennas that cover the same frequencies, phased antenna arrays  54 - 2 ′ and  54 - 2 ″ may fit within notch  8  and may still exhibit satisfactory antenna efficiency despite the presence of speaker port  16  and other components  152 . 
     If desired, multiple phased antenna arrays  54 - 2  may be aligned with multiple notches in peripheral conductive housing structures  12 W (e.g., multiple notches  150  of  FIG.  16   ) and/or may be aligned with notch  8  in display module  68 . Phased antenna arrays  54 - 2  may provide beam steering in one or more frequency bands between 10 GHz and 300 GHz within some or all of the hemisphere over the front face of device  10 . When combined with the operation of phased antenna array  54 - 1  at the rear of device  10  ( FIG.  5   ), the phased antenna arrays in device  10  may collectively provide coverage within approximately a full sphere around device  10 . The presence of parasitic elements in the antennas of phased antenna arrays  54 - 2  may serve to mitigate cross-polarization interference in the phased antenna arrays, thereby optimizing radio-frequency performance of the phased antenna arrays. 
     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: 20200417
Publication Date: 20241126
Grant Date: 20241126
Priority Date: 20200417
Inventors: AVSER, BILGEHAN
RAJAGOPALAN, HARISH
EDWARDS, JENNIFER M.
PAULOTTO, Simone
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/385", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q19/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/06", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/242", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2258", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0485", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0485", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0485", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0485", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/385", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0485", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 77920136