PATENT DOCUMENT

Publication Number: US-10868356-B1
Application Number: US-201916563703-A
Country: US
Kind Code: B1

Title: Electronic devices having extended antenna grounding rings

Abstract:
An electronic device may include an antenna element, coil, sensor board, and grounding ring structures. The coil may receive wireless charging signals through the grounding ring structures. The grounding ring structures may include concentric ring-shaped traces separated by at least one gap. The ring-shaped traces and gaps may configure the grounding ring structures to short antenna currents at relatively high frequencies from the antenna element to a ground trace on the sensor board while blocking currents at relatively low frequencies. The grounding ring structures may include conductive wings that increase capacitive coupling between the grounding ring structures and the antenna element. The grounding ring structures may be soldered to the antenna element. The antenna element and the grounding ring structures may be formed from traces patterned on the same substrate. The ground trace may form part of an antenna without substantially impairing wireless charging efficiency of the coil.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 an antenna having an antenna resonating element extending around an axis; 
 a first substrate having a ground trace that forms part of an antenna ground for the antenna; 
 a second substrate; and 
 conductive traces on the second substrate, wherein the conductive traces comprise:
 ring-shaped traces extending around the axis, 
 a conductive wing separated from the ring-shaped traces by a region of the second substrate, and 
 a conductive bridge that bridges the region and couples the conductive wing to the ring-shaped traces, wherein the conductive wing is configured to receive an antenna current from the antenna resonating element via near-field capacitive coupling, the conductive traces being configured to short the antenna current to the ground trace on the first substrate. 
 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the ring-shaped traces are concentric about the axis and are separated by at least one gap. 
     
     
       3. The electronic device defined in  claim 2 , wherein the conductive bridge comprises segments of conductive traces that are separated by at least one additional gap. 
     
     
       4. The electronic device defined in  claim 3 , wherein the conductive wing comprises a continuous piece of conductive material that does not include any gaps. 
     
     
       5. The electronic device defined in  claim 2 , further comprising:
 coil structures configured to receive wireless charging signals through the second substrate, wherein the ring-shaped traces and the at least one gap configure the conductive traces to convey the antenna current between the ring-shaped traces and to the ground trace on the first substrate while blocking currents at a frequency of the wireless charging signals from flowing between the ring-shaped traces. 
 
     
     
       6. The electronic device defined in  claim 5 , wherein the antenna current is at a second frequency greater than the first frequency, the ring-shaped traces being configured to exhibit a first impedance in a radial direction towards the axis at the first frequency and a second impedance in the radial direction towards the axis at the second frequency, the second impedance being less than the first impedance. 
     
     
       7. The electronic device defined in  claim 1 , wherein the conductive traces further comprise:
 an additional conductive wing separated from the ring-shaped traces by the region, wherein the conductive wing and the additional conductive wing are located at opposing sides of the ring-shaped traces; and 
 an additional conductive bridge that bridges the region and couples the additional conductive wing to the ring-shaped traces, wherein the additional conductive wing is configured to receive the antenna current from the antenna resonating element via near-field capacitive coupling. 
 
     
     
       8. The electronic device defined in  claim 1 , wherein the conductive traces further comprise:
 first, second, and third additional conductive wings separated from the ring-shaped traces by the region; and 
 first, second, and third additional conductive bridges that bridge the region and couple the first, second, and third additional conductive wings, respectively, to the ring-shaped traces, wherein the first, second, and third additional conductive wings are configured to receive the antenna current from the antenna resonating element via near-field capacitive coupling. 
 
     
     
       9. The electronic device defined in  claim 1 , further comprising a sensor mounted to the first substrate. 
     
     
       10. The electronic device defined in  claim 1 , wherein the electronic device has opposing first and second faces and further comprises:
 a display at the first face; 
 a housing having a housing wall at the second face, wherein the antenna is configured to convey radio-frequency signals corresponding to the antenna current through the housing wall; 
 a battery in the housing; 
 coil structures extending around the axis, wherein the coil structures are configured to receive wireless charging signals through the second substrate and to charge the battery using the received wireless charging signals; and 
 a sensor mounted to the first substrate and configured to gather sensor data through the housing wall. 
 
     
     
       11. The electronic device defined in  claim 10 , wherein the second substrate laterally extends around the first substrate. 
     
     
       12. The electronic device defined in  claim 11 , further comprising:
 conductive interconnect structures that couple the ring-shaped traces to the ground trace on the first substrate. 
 
     
     
       13. The electronic device defined in  claim 12 , wherein the conductive interconnect structures comprise solder. 
     
     
       14. An electronic device comprising:
 a ground trace; 
 a dielectric substrate; 
 ring-shaped conductive traces that are patterned on the dielectric substrate and concentric about an axis; 
 an antenna resonating element trace patterned on the dielectric substrate, wherein the antenna resonating element trace follows a loop path around the axis and laterally surrounds the ring-shaped conductive traces on the dielectric substrate; 
 a bridging trace patterned on the dielectric substrate, wherein the bridging trace couples the ring-shaped conductive traces to the antenna resonating element trace; and 
 a conductive coil overlapping the ring-shaped conductive traces and configured to receive wireless charging signals at a first frequency, wherein the antenna resonating element conveys an antenna current at a second frequency greater than the first frequency, the ring-shaped conductive traces and the bridging trace being configured to convey the antenna current to the ground traces while blocking currents at the first frequency from flowing between the ring-shaped conductive traces. 
 
     
     
       15. The electronic device defined in  claim 14 , further comprising:
 a printed circuit board, wherein the ground trace is patterned on the printed circuit board; and 
 solder that couples the ring-shaped conductive traces to the ground trace. 
 
     
     
       16. The electronic device defined in  claim 15 , further comprising an infrared light sensor mounted to the printed circuit board. 
     
     
       17. The electronic device defined in  claim 14 , wherein the conductive coil is configured to receive the wireless charging signals through the ring-shaped conductive traces. 
     
     
       18. A wristwatch having a first face and a second face opposite the first face, the wristwatch comprising:
 a display at the first face; 
 a housing wall at the second face 
 an antenna resonating element configured to transmit radio-frequency signals at a first frequency through the housing wall; 
 coil structures configured to receive wireless power through the housing wall at a second frequency that is less than the first frequency; 
 a circuit board having a ground trace, wherein an axis extends through a lateral surface of the circuit board, the coil structures and the antenna resonating element laterally extending around the axis; 
 antenna grounding ring structures laterally extending around the axis, wherein the antenna grounding ring structures are configured to short current at the first frequency to the ground trace while blocking current at the second frequency from flowing to the ground trace; and 
 solder that shorts the antenna grounding ring structures to the antenna resonating element. 
 
     
     
       19. The wristwatch defined in  claim 18 , wherein the antenna grounding ring structures comprise ring-shaped conductive traces patterned on a dielectric substrate and concentric about the axis, the ring-shaped conductive traces being galvanically connected to the antenna resonating element by the solder. 
     
     
       20. The wristwatch defined in  claim 18 , wherein the antenna grounding ring structures comprise conductive traces extending radially outwards with respect to the axis.

Description:
BACKGROUND 
     This relates to electronic devices, and more particularly, to electronic devices with wireless circuitry. 
     Electronic devices are often provided with wireless communications capabilities. To satisfy consumer demand for small form factor electronic devices, manufacturers are continually striving to implement wireless circuitry such as antenna components using compact structures. 
     At the same time, larger antenna volumes generally allow antennas to exhibit greater efficiency bandwidth. In addition, because antennas have the potential to interfere with each other and with other components in a wireless device, care must be taken when incorporating antennas into an electronic device to ensure that the antennas and wireless circuitry are able to exhibit satisfactory performance over a wide range of operating frequencies. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices. 
     SUMMARY 
     An electronic device such as a wristwatch may be provided with a housing, wireless circuitry, and a battery. The device may include a display at a front face of the housing. The housing may include a rear housing wall at a rear face of the housing. The wireless circuitry may include coil structures and an antenna having an antenna resonating element. The antenna resonating element may transmit and receive radio-frequency signals at a first frequency through the rear housing wall. The coil structures may receive wireless charging signals at a second frequency that is less than the first frequency through the rear housing wall. The wireless charging signals may be used to charge the battery. A sensor board may be mounted at the rear housing wall and may include sensors that gather sensor data through the rear housing wall. 
     An axis may extend through a lateral surface of the sensor board. The coil structures and the antenna resonating element may follow loop paths around the axis. The antenna resonating element may laterally surround the coil structures and the sensor board. Ferrite structures may be included in the coil structures. Ground traces on the sensor board may form part of the antenna. If care is not taken, the radio-frequency signals conveyed by the antenna resonating element may produce currents on the coil structures that are lost to the ferrite structures, thereby limiting efficiency for the antenna. 
     To mitigate these issues, antenna grounding ring structures may be provided for the antenna. The antenna grounding ring structures may be formed from concentric ring-shaped traces on a flexible printed circuit. The ring-shaped traces may laterally extend around the axis and may partially overlap the antenna resonating element. Antenna currents at the first frequency may be coupled onto the ring-shaped traces by near-field capacitive coupling. The coil structures may receive the wireless charging signals through the antenna grounding ring structures. 
     The ring-shaped traces may be separated by at least one gap. The ring-shaped traces and the at least one gap may configure the antenna grounding ring structures to short antenna currents at the first frequency from the antenna resonating element to the ground trace on the sensor board while blocking currents at the second frequency from flowing between the ring-shaped traces. This may allow the ground traces to form part of the antenna, thereby maximizing antenna volume and efficiency bandwidth, without substantially impairing the wireless charging efficiency of the coil structures. 
     If desired, the antenna grounding ring structures may include one or more conductive wings on the flexible printed circuit. The conductive wings may be separated from the ring-shaped traces by a gap region on the flexible printed circuit. The conductive wings may be coupled to the ring-shaped traces by conductive bridges. The conductive bridges may be formed from segments of conductive traces separated by gaps. The conductive wings may be formed from continuous regions of conductive traces (e.g., regions of solid conductive material without any gaps). The conductive wings may overlap the antenna resonating element and may receive the antenna currents from the antenna resonating element via near-field electromagnetic coupling. The conductive wings may increase the capacitive coupling between the antenna grounding ring structures and the antenna resonating element to help flatten the efficiency response of the antenna at relatively high frequencies. 
     If desired, conductive interconnect structures may electrically connect the ring-shaped traces and/or the conductive wings to the antenna resonating element. The conductive interconnect structures may include solder. In one suitable arrangement, the ring-shaped traces may be galvanically connected to the antenna resonating element by the solder. In another suitable arrangement, the conductive wings may be galvanically connected to the antenna resonating element by the solder. The antenna current may flow from the antenna resonating element to the antenna grounding ring structures through the conductive interconnect structures. 
     If desired, the antenna resonating element and the ring-shaped traces may both be patterned on the same surface of the same dielectric substrate. Bridging traces on the dielectric substrate may couple the ring-shaped traces to the antenna resonating element. The antenna currents may be shorted to the ground traces through the bridging traces and the ring-shaped traces. The coil structures may overlap the ring-shaped traces and the dielectric substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless circuitry in accordance with some embodiments. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless circuitry in accordance with some embodiments. 
         FIG. 3  is a diagram of illustrative wireless circuitry in an electronic device in accordance with some embodiments. 
         FIG. 4  is a cross-sectional side view of an illustrative electronic device having an antenna overlapping a rear housing wall in accordance with some embodiments. 
         FIG. 5  is a cross-sectional side view of an illustrative electronic device having antenna grounding ring structures in accordance with some embodiments. 
         FIG. 6  is a bottom-up view showing how illustrative antenna grounding ring structures may overlap wireless charging coil structures and an antenna resonating element in accordance with some embodiments. 
         FIG. 7  is a bottom-up view showing how illustrative antenna grounding ring structures may be formed on a flexible printed circuit substrate in accordance with some embodiments. 
         FIG. 8  is a bottom-up view showing how illustrative antenna grounding ring structures may include concentric rings of conductive traces separated by gaps in accordance with some embodiments. 
         FIG. 9  is a plot of antenna performance (antenna efficiency) as a function of frequency showing how illustrative antenna grounding ring structures may optimize antenna efficiency for an antenna in accordance with some embodiments. 
         FIG. 10  is a bottom-up view showing how illustrative antenna grounding ring structures may include conductive wings to extend the region of overlap with an overlying antenna resonating element in accordance with some embodiments. 
         FIG. 11  is a bottom-up view showing how illustrative antenna grounding ring structures may include two conductive wings on opposing sides of concentric ring-shaped traces in accordance with some embodiments. 
         FIG. 12  is a bottom-up view showing how illustrative antenna grounding ring structures may be electrically connected to an antenna resonating element using conductive interconnect structures such as solder in accordance with some embodiments. 
         FIG. 13  is a side view showing how an illustrative antenna resonating element and illustrative antenna grounding ring structures may both be patterned on the same dielectric substrate in accordance with some embodiments. 
         FIG. 14  is a bottom-up view of an illustrative substrate having an antenna resonating element and antenna grounding ring structures patterned thereon in accordance with some embodiments. 
         FIG. 15  is a plot of antenna performance (antenna efficiency) as a function of frequency showing how illustrative conductive wings in antenna grounding ring structures may optimize antenna efficiency at relatively high frequencies in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with wireless circuitry (sometimes referred to herein as wireless communications circuitry). The wireless circuitry may be used to support wireless communications in multiple wireless communications bands. Communications bands (sometimes referred to herein as frequency bands) handled by the wireless circuitry can include satellite navigation system communications bands, cellular telephone communications bands, wireless local area network communications bands, wireless personal area network communications bands, near-field communications bands, ultra-wideband communications bands, or other wireless communications bands. 
     The wireless circuitry may include one or more antennas. The antennas of the wireless circuitry can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, patch antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. 
     Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a wristwatch (e.g., a smart watch). Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14 . Display  14  may be mounted in a housing such as housing  12 . Housing  12 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  12  may be formed using a unibody configuration in which some or all of housing  12  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). Housing  12  may have metal sidewalls such as sidewalls  12 W or sidewalls formed from other materials. Examples of metal materials that may be used for forming sidewalls  12 W include stainless steel, aluminum, silver, gold, metal alloys, or any other desired conductive material. Sidewalls  12 W may sometimes be referred to herein as housing sidewalls  12 W or conductive housing sidewalls  12 W. 
     Display  14  may be formed at (e.g., mounted on) the front side (face) of device  10 . Housing  12  may have a rear housing wall on the rear side (face) of device  10  such as rear housing wall  12 R that opposes the front face of device  10 . Conductive housing sidewalls  12 W may surround the periphery of device  10  (e.g., conductive housing sidewalls  12 W may extend around peripheral edges of device  10 ). Rear housing wall  12 R may be formed from conductive materials and/or dielectric materials. Examples of dielectric materials that may be used for forming rear housing wall  12 R include plastic, glass, sapphire, ceramic, wood, polymer, combinations of these materials, or any other desired dielectrics. 
     Rear housing wall  12 R and/or display  14  may extend across some or all of the length (e.g., parallel to the X-axis of  FIG. 1 ) and width (e.g., parallel to the Y-axis) of device  10 . Conductive housing sidewalls  12 W may extend across some or all of the height of device  10  (e.g., parallel to Z-axis). Conductive housing sidewalls  12 W and/or rear sing 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 or dielectric 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 housing walls  12 R and/or  12 W from view of the user). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. Display  14  may also be force sensitive and may gather force input data associated with how strongly a user or object is pressing against display  14 . 
     Display  14  may include an array of display pixels formed from liquid crystal display (LCD) components, an array of electrophoretic display pixels, an array of plasma display pixels, an array of organic light-emitting diode (OLED) display pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. Display  14  may be protected using a display cover layer. The display cover layer may be formed from a transparent material such as glass, plastic, sapphire or other crystalline dielectric materials, ceramic, or other clear materials. The display cover layer may extend across substantially all of the length and width of device  10 , for example. 
     Device  10  may include buttons such as button  18 . There may be any suitable number of buttons in device  10  (e.g., a single button, more than one button, two or more buttons, five or more buttons, etc.). Buttons may be located in openings in housing  12  (e.g., openings in conductive housing sidewall  12 W or rear housing wall  12 R) or in an opening in display  14  (as examples). Buttons may be rotary buttons, sliding buttons, buttons that are actuated by pressing on a movable button member, etc. Button members for buttons such as button  18  may be formed from metal, glass, plastic, or other materials. Button  18  may sometimes be referred to as a crown in scenarios where device  10  is a wristwatch device. 
     Device  10  may, if desired, be coupled to a strap such as strap  16 . Strap  16  may be used to hold device  10  against a user&#39;s wrist (as an example). Strap  16  may sometimes be referred to herein as wrist strap  16 . In the example of  FIG. 1 , wrist strap  16  is connected to opposing sides of device  10 . Conductive housing sidewalls  12 W may include attachment structures for securing wrist strap  16  to housing  12  (e.g., lugs or other attachment mechanisms that configure housing  12  to receive wrist strap  16 ). Configurations that do not include straps may also be used for device  10 . 
     A schematic diagram showing illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry  28 . Control circuitry  28  may include storage such as storage circuitry  24 . Storage circuitry  24  may include hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. 
     Control circuitry  28  may include processing circuitry such as processing circuitry  26 . Processing circuitry  26  may be used to control the operation of device  10 . Processing circuitry  26  may include on one or more microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), etc. Control circuitry  28  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  24  (e.g., storage circuitry  24  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  24  may be executed by processing circuitry  26 . 
     Control circuitry  28  may be used to run software on device  10  such as external node location applications, satellite navigation applications, internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), IEEE 802.15.4 ultra-wideband communications protocols or other ultra-wideband communications protocols, etc. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  20 . Input-output circuitry  20  may include input-output devices  22 . Input-output devices  22  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  22  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  22  may include touch screens, displays without touch sensor capabilities, buttons, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, vibrators or other haptic feedback engines, digital data port devices, light sensors (e.g., infrared light sensors, visible light sensors, etc.), light-emitting diodes, motion sensors (accelerometers), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), etc. 
     Input-output circuitry  22  may include wireless circuitry  34 . Wireless circuitry  34  may include wireless power receiving coil structures such as coil structures  44  and wireless power receiver circuitry such as wireless power receiver circuitry  42 . Device  10  may use wireless power receiver circuitry  42  and coil structures  44  to receive wirelessly transmitted power (e.g., wireless charging signals) from a wireless power adapter (e.g., a wireless power transmitting device such as a wireless charging mat or other device). Coil structures  44  may include one or more inductive coils that use resonant inductive coupling (near field electromagnetic coupling) with a wireless power transmitting coil on the wireless power adapter. 
     The wireless power adapter may pass AC currents through the wireless power transmitting coil to produce a time varying electromagnetic (e.g., magnetic) field that is received as wireless power (wireless charging signals) by coil structures  44  in device  10 . An illustrative frequency for the wireless charging signals is 200 kHz. Other frequencies may be used, if desired (e.g., frequencies in the kHz range, the MHz range, or in the GHz range, frequencies of 1 kHz to 1 MHz, frequencies of 1 kHz to 100 MHz, frequencies less than 100 MHz, frequencies less than 1 MHz, etc.). When the time varying electromagnetic field is received by coil structures  44 , corresponding alternating-current (AC) currents are induced in the coil structures. Wireless power receiver circuitry  42  may include converter circuitry such as rectifier circuitry. The rectifier circuitry may include rectifying components such as synchronous rectification metal-oxide-semiconductor transistors arranged in a bridge network, and may convert these currents from coil structures  44  into a DC voltage for powering device  10 . The DC voltage produced by the rectifier circuitry in wireless power receiver circuitry  42  can be used in powering (charging) an energy storage device such as battery  46  and can be used in powering other components in device  10 . 
     To support wireless communications, wireless circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas such as antennas  40 , transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless circuitry  34  may include radio-frequency transceiver circuitry for handling various radio-frequency communications bands. For example, wireless circuitry  34  may include wireless local area network (WLAN) and wireless personal area network (WPAN) transceiver circuitry  32 . Transceiver circuitry  32  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications or other WLAN bands and may handle the 2.4 GHz Bluetooth® communications band or other WPAN bands. Transceiver circuitry  32  may sometimes be referred to herein as WLAN/WPAN transceiver circuitry  32 . 
     Wireless circuitry  34  may use cellular telephone transceiver circuitry  36  for handling wireless communications in frequency ranges (communications bands) such as a cellular low band (LB) from 600 to 960 MHz, a cellular low-midband (LMB) from 1410 to 1510 MHz, a cellular midband (MB) from 1710 to 2170 MHz, a cellular high band (HB) from 2300 to 2700 MHz, a cellular ultra-high band (UHB) from 3300 to 5000 MHz, or other communications bands between 600 MHz and 5000 MHz or other suitable frequencies (as examples). Cellular telephone transceiver circuitry  36  may handle voice data and non-voice data. 
     Wireless circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry  30  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver circuitry  30  are received from a constellation of satellites orbiting the earth. Wireless circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless circuitry  34  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) transceiver circuitry  38  (e.g., an NFC transceiver operating at 13.56 MHz or another suitable frequency), etc. 
     In NFC links, wireless signals are typically conveyed over a few inches at most. In satellite navigation system links, cellular telephone links, and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. In WLAN and WPAN links at 2.4 and 5 GHz and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. Antenna diversity schemes may be used if desired to ensure that the antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     Wireless circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from slot antenna structures, loop antenna structures, patch antenna structures, stacked patch antenna structures, antenna structures having parasitic elements, inverted-F antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antennas, dipole antenna structures, Yagi (Yagi-Uda) antenna structures, surface integrated waveguide structures, hybrids of these designs, etc. If desired, one or more of antennas  40  may be cavity-backed antennas. 
     Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna whereas another type of antenna is used in forming a remote wireless link antenna. If desired, space may be conserved within device  10  by using a single antenna to handle two or more different communications bands. For example, a single antenna  40  in device  10  may be used to handle communications in a WiFi® or Bluetooth® communication band at 2.4 GHz, a GPS communications band at 1575 MHz, a WiFi® or Bluetooth® communications band at 5.0 GHz, and one or more cellular telephone communications bands such as a cellular low band between about 600 MHz and 960 MHz and/or a cellular midband between about 1700 MHz and 2200 MHz. If desired, a combination of antennas for covering multiple frequency bands and dedicated antennas for covering a single frequency band may be used. 
     It may be desirable to implement at least some of the antennas in device  10  using portions of electrical components that would otherwise not be used as antennas and that support additional device functions. As an example, it may be desirable to induce antenna currents in components such as display  14  ( FIG. 1 ), so that display  14  and/or other electrical components (e.g., a touch sensor, near-field communications loop antenna, conductive display assembly or housing, conductive shielding structures, etc.) can serve as part of an antenna for Wi-Fi, Bluetooth, GPS, cellular frequencies, and/or other frequencies without the need to incorporate separate bulky antenna structures in device  10 . Conductive portions of housing  12  ( FIG. 1 ) may be used to form part of an antenna ground for one or more antennas  40 . 
     A schematic diagram of wireless circuitry  34  is shown in  FIG. 3 . As shown in  FIG. 3 , wireless circuitry  34  may include transceiver circuitry  48  (e.g., cellular telephone transceiver circuitry  36  of  FIG. 2 , WLAN/WPAN transceiver circuitry  32 , etc.) that is coupled to a given antenna  40  using a radio-frequency transmission line path such as radio-frequency transmission line path  50 . 
     To provide antenna structures such as antenna  40  with the ability to cover different frequencies of interest, antenna  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna  40  may be provided with adjustable circuits such as tunable components that tune the antenna over communications (frequency) bands of interest. The tunable components may be part of a tunable filter or tunable impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and antenna ground, etc. 
     Radio-frequency transmission line path  50  may include one or more radio-frequency transmission lines (sometimes referred to herein simply as transmission lines). Radio-frequency transmission line path  50  (e.g., the transmission lines in radio-frequency transmission line path  50 ) may include a positive signal conductor such as signal conductor  52  and a ground signal conductor such as ground conductor  54 . 
     The transmission lines in radio-frequency transmission line path  50  may, for example, include coaxial cable transmission lines (e.g., ground conductor  54  may be implemented as a grounded conductive braid surrounding signal conductor  52  along its length), stripline transmission lines (e.g., where ground conductor  54  extends along two sides of signal conductor  52 ), a microstrip transmission line (e.g., where ground conductor  54  extends along one side of signal conductor  52 ), coaxial probes realized by a metalized via, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide structures (e.g., coplanar waveguides or grounded coplanar waveguides), combinations of these types of transmission lines and/or other transmission line structures, etc. 
     Transmission lines in radio-frequency transmission line path  50  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, radio-frequency transmission line path  50  may include transmission line conductors (e.g., signal conductors  52  and ground conductors  54 ) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive). The multilayer laminated structures may, if desired, be folded or bent in multiple dimensions (e.g., two or three dimensions) and may maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). 
     A matching network may include components such as inductors, resistors, and capacitors used in matching the impedance of antenna  40  to the impedance of radio-frequency transmission line path  50 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna(s)  40  and may be tunable and/or fixed components. 
     Radio-frequency transmission line path  50  may be coupled to antenna feed structures associated with antenna  40 . As an example, antenna  40  may form an inverted-F antenna, a planar inverted-F antenna, a patch antenna, a loop antenna, or other antenna having an antenna feed  56  with a positive antenna feed terminal such as terminal  58  and a ground antenna feed terminal such as terminal  60 . Positive antenna feed terminal  58  may be coupled to an antenna resonating (radiating) element within antenna  40 . Ground antenna feed terminal  60  may be coupled to an antenna ground in antenna  40 . Signal conductor  52  may be coupled to positive antenna feed terminal  58  and ground conductor  54  may be coupled to ground antenna feed terminal  60 . 
     Other types of antenna feed arrangements may be used if desired. For example, antenna  40  may be fed using multiple feeds each coupled to a respective port of transceiver circuitry  48  over a corresponding transmission line. If desired, signal conductor  52  may be coupled to multiple locations on antenna  40  (e.g., antenna  40  may include multiple positive antenna feed terminals coupled to signal conductor  52  of the same radio-frequency transmission line path  50 ). Switches may be interposed on the signal conductor between transceiver circuitry  48  and the positive antenna feed terminals if desired (e.g., to selectively activate one or more positive antenna feed terminals at any given time). The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Device  10  may include multiple antennas that convey radio-frequency signals through different sides of device  10 . For example, device  10  may include at least first antenna that conveys radio-frequency signals through the front face of device  10  (e.g., display  14  of  FIG. 1 ) and a second antenna that conveys radio-frequency signals through the rear face of device  10  (e.g., rear housing wall  12 R of  FIG. 1 ). 
       FIG. 4  is a cross-sectional side view of electronic device  10  showing how a given antenna  40  may be mounted within device  10  for conveying (radiating) radio-frequency signals through rear housing wall  12 R. As shown in  FIG. 4 , display  14  may form the front face of device  10  whereas rear housing wall  12 R forms the rear face of device  10 . In the example of  FIG. 4 , rear housing wall  12 R is formed from a dielectric material such as glass, sapphire, ceramic, or plastic. This is merely illustrative and, if desired, rear housing wall  12 R may also include conductive portions (e.g., a conductive frame surrounding one or more dielectric windows in rear housing wall  12 R, conductive cosmetic layers, etc.). Conductive housing sidewalls  12 W may extend from the rear face to the front face of device  10  (e.g., from rear housing wall  12 R to display  14 ). 
     Strap  16  may be secured to conductive housing sidewalls  12 W using corresponding attachment structures  70 . Attachment structures  70  may include lugs, spring structures, clasp structures, adhesive structures, or any other desired attachment mechanisms. Strap  16  may be formed using any desired materials (e.g., metal materials, dielectric materials, or combinations of metal and dielectric materials). If desired, strap  16  may be removed from attachment structures  70  (e.g., so that a user of device  10  can swap in different straps having similar or different materials). 
     Display  14  may include a display module  64  (sometimes referred to herein as display stack  64 , display assembly  64 , or active area  64  of display  14 ) and a display cover layer  62 . Display module  64  may, for example, form an active area or portion of display  14  that displays images and/or receives touch sensor input. The lateral portion of display  14  that does not include display module  64  (e.g., portions of display  14  formed from display cover layer  62  but without an underlying portion of display module  64 ) may sometimes be referred to herein as the inactive area or portion of display  14  because this portion of display  14  does not display images or gather touch sensor input. 
     Display module  64  may include conductive components (sometimes referred to herein as conductive display structures) that are used in forming portions of an antenna that radiates through the front face of device  10  (e.g., an antenna having a radiating element such as a radiating slot element defined by display module  64  and/or conductive housing sidewalls  12 W). The conductive display structures in display module  64  may, for example, have planar shapes (e.g., planar rectangular shapes, planar circular shapes, etc.) and may be formed from metal and/or other conductive material that carries antenna currents for a front-facing antenna in device  10 . The conductive display structures may include a frame for display module  64 , pixel circuitry, touch sensor electrodes, an embedded near-field communications antenna, etc. 
     Display cover layer  62  may be formed from an optically transparent dielectric such as glass, sapphire, ceramic, or plastic. Display module  64  may display images (e.g., emit image light) through display cover layer  62  for view by a user and/or may gather touch or force sensor inputs through display cover layer  62 . If desired, portions of display cover layer  62  may be provided with opaque masking layers (e.g., ink masking layers) and/or pigment to obscure the interior of device  10  from view of a user. 
     Substrates such as substrate  66  (e.g., a rigid or flexible printed circuit board, integrated circuit or chip, integrated circuit package, etc.) may be located within the interior of device  10 . Substrate  66  may be, for example, a main logic board (MLB) or other logic board for device  10 . Other components such as components  68  (e.g., components used in forming control circuitry  28  and/or input-output circuitry  20  of  FIG. 2 , battery  46 , etc.) may be mounted to substrate  66  and/or elsewhere within the interior of device  10 . 
     As shown in  FIG. 4 , a given antenna  40  may be mounted within device  10  for radiating through rear housing wall  12 R. Ground traces  67  may be formed on substrate  66  and may form part of the antenna ground for antenna  40 . Conductive housing sidewalls  12 W may also form part of the antenna ground for antenna  40  (e.g., ground traces  67  on substrate  66  may be electrically shorted to conductive housing sidewalls  12 W). Conductive portions of other components in device  10  may also form part of the antenna ground for antenna  40  (e.g., ground traces  67  on substrate  66 , conductive housing sidewalls  12 W, and/or conductive portions of other components in device  10  may be held at a ground or reference potential). 
     Antenna  40  may include an antenna resonating element  82  formed from conductive traces on a substrate such as substrate  84 . Substrate  84  may be a plastic substrate, a flexible printed circuit substrate, a rigid printed circuit substrate, a ceramic substrate, or any other desired dielectric substrate. The conductive traces in antenna resonating element  82  (sometimes referred to herein as antenna radiating element  82 , resonating element  82 , radiating element  82 , or antenna element  82 ) may, for example, be patterned onto substrate  84  using a laser direct structuring (LDS) process. In another suitable arrangement, antenna resonating element  82  may be formed from metal foil, layers of sheet metal, conductive portions of the housing for device  10 , etc. 
     Antenna resonating element  82  may be a patch antenna resonating element, an inverted-F antenna resonating element, a planar inverted-F antenna resonating element, a monopole resonating element, a dipole resonating element, a loop resonating element, another type of antenna resonating element, and/or a combination of these types of antenna resonating elements. If desired, antenna resonating element  82  and/or substrate  84  may laterally extend circumferentially around central axis  94  (e.g., antenna resonating element  82  may lie within a given plane or surface and may have a loop shape that extends around an opening, where central axis  94  runs orthogonally through the opening). Positive antenna feed terminal  58  for antenna  40  may be coupled to antenna resonating element  82 . The ground antenna feed terminal for antenna  40  (not shown in  FIG. 4  for the sake of clarity) may be coupled to conductive housing sidewalls  12 W, ground traces  67  on substrate  66 , or any other desired portion of the antenna ground for antenna  40 . 
     Rear housing wall  12 R may extend across substantially all of the length and width of device  10  (e.g., in the X-Y plane). Rear housing wall  12 R may be optically opaque or optically transparent or may include both optically opaque and optically transparent portions (e.g., rear housing wall  12 R may include optically transparent windows in an otherwise optically opaque member). Antenna resonating element  82  may overlap rear housing wall  12 R and may, if desired, be spaced apart from rear housing wall  12 R, pressed against rear housing wall  12 R, adhered to rear housing wall  12 R, etc. In this way, antenna  40  may be formed at or adjacent to the rear face of device  10  for radiating through rear housing wall  12 R. If desired, antenna resonating element  82  may conform to the shape of the interior surface of rear housing wall  12 R (e.g., antenna resonating element  82  need not be planar). In the example of  FIG. 4 , the interior surface of rear housing wall  12 R has a slightly curved or concave shape (e.g., to form a protruding portion  72  that increases the total volume for components within device  10  relative to scenarios where the interior surface of rear housing wall  12 R is flat). 
     Antenna  40  may transmit and receive radio-frequency signals (e.g., in at least the cellular low band, the cellular low-midband, the cellular midband, and/or the cellular high band) through rear housing wall  12 R. The radio-frequency signals transmitted by antenna  40  may be shielded from electrical components  68  and the antenna at the front face of device  10  by ground traces  67  on substrate  66 , for example. Similarly, ground traces  67  and substrate  66  may shield antenna  40  from components  68  and the antenna at the front face of device  10 , thereby maximizing isolation between the antennas in device  10  despite the relatively small size of device  10 . 
     By forming antenna  40  at rear housing wall  12 R, the vertical height of device  10  (e.g., parallel to the Z-axis of  FIG. 4 ) may be shorter than would otherwise be possible in scenarios where the corresponding antenna resonating element is located elsewhere on device  10  (while still allowing antenna  40  to exhibit satisfactory antenna efficiency). As an example, the vertical height of device  10  may be less than or equal to 11.4 mm, less than 15 mm, between 8 and 11.4 mm, or any other desired height while still allowing antenna  40  to operate with satisfactory antenna efficiency. 
     In practice, the wireless performance of antenna  40  may be optimized by the presence of an external object adjacent to rear housing wall  12 R. For example, the presence of the user&#39;s wrist  80  adjacent to rear housing wall  12 R when the user is wearing device  10  may enhance the wireless performance of antenna  40 . During operation, antenna  40  may transmit and/or receive radio-frequency signals having electric fields (E) that are oriented normal to the surfaces of rear housing wall  12 R and wrist  80 . These signals may sometimes be referred to as surface waves, which are then propagated along the surface of wrist  80  and outwards, as shown by paths  76  (e.g., antenna resonating element  82  and wrist  80  may serve as a waveguide that directs the surface waves outwards). This may allow the radio-frequency signals conveyed by antenna  40  to be properly received by external communications equipment (e.g., a wireless base station) even though antenna  40  is located close to wrist  80  and typically pointed away from the external communications equipment. 
     If desired, a sensor board such as sensor board  88  may be mounted within device  10  at or adjacent to rear housing wall  12 R. Central axis  94  may extend (e.g., orthogonally) through a lateral surface of sensor board  88 . Sensor board  88  may be separated from rear housing wall  12 R, pressed against rear housing wall  12 R, adhered to rear housing wall  12 R, etc. Sensor board  88  may overlap protruding portion  72  of rear housing wall  12 R and may be partially or completely located within protruding portion  72 . Sensor board  88  may include a rigid printed circuit board, flexible printed circuit, integrated circuit chip, integrated circuit package, plastic substrate, or other substrates for supporting one or more sensors  92  (e.g., one or more sensors  92  may be mounted to sensor board  88 ). Sensors  92  may, for example, include sensors in input-output devices  22  of  FIG. 2 . 
     If desired, sensor electrodes  74  may be formed at or on rear housing wall  12 R (e.g., sensor electrodes  74  may be at least partially embedded within the dielectric material of rear housing wall  12 R as shown in  FIG. 4 ). In this example, sensor electrodes  74  may be coupled to sensor circuitry on sensor board  88  using one or more conductive paths (not shown in  FIG. 4  for the sake of clarity). Sensor electrodes  74  may, for example, be electrocardiogram (ECG or EKG) electrodes. Sensor circuitry on sensor board  74  may sense the electrical activity of a user&#39;s heart using sensor electrodes  74  while the user wears device  10 , for example. In another suitable arrangement, sensor electrodes  74  may be mounted to sensor board  88 . Sensor board  88  may include ground traces  90 . Ground traces  90  may be held at a ground or reference potential. If desired, ground traces  90  may be shorted to conductive housing sidewalls  12 W, ground traces  67 , or other ground structures in device  10 . 
     Sensors  92  may include one or more sensors such as a light sensor, proximity sensor, touch sensor, or other sensors. As one example, sensors  92  may include at least one infrared light emitter and at least one infrared light sensor. The infrared light emitter may emit infrared light through rear housing wall  12 R (e.g., through an infrared-transparent window in rear housing wall  12 R). The infrared light sensor may receive a reflected version of the emitted infrared light that has been reflected off of an external object in the vicinity of device  10  such as wrist  80  of a user (e.g., a user who is wearing device  10  on their wrist in scenarios where device  10  is a wristwatch). This example is merely illustrative and, if desired, sensors  92  may include any other desired components or may be omitted. 
     Coil structures  44  may also be mounted within device  10  at or adjacent to rear housing wall  12 R. Coil structures  44  may be spaced apart from rear housing wall  12 R, pressed against rear housing wall  12 R, adhered to rear housing wall  12 R, etc. As shown in  FIG. 4 , antenna  40  (e.g., antenna resonating element  82 ) may laterally extend around (surround) coil structures  44  (e.g., coil structures  44  may lie within an opening in antenna resonating element  82 ). Coil structures  44  may also circumferentially surround central axis  94  (e.g., coil structures  44  may laterally extend around central axis  94  within the X-Y plane or another surface). In this way, coil structures  44  and antenna  40  may extend concentrically around central axis  94 . Coil structures  44  may laterally surround sensor board  88  and/or an opening that overlaps sensor board  88 . 
     Coil structures  44  may receive wireless charging signals through rear housing wall  12 R (e.g., when device  10  is placed on a wireless power adapter or other wireless power transmitting device). The wireless charging signals may induce currents on coil structures  44  that are used by wireless power receiver circuitry  42  for charging battery  46  ( FIG. 2 ). Coil structures  44  may include a single conductive coil (e.g., an inductive coil) or more than one conductive coil. In one suitable arrangement, coil structures  44  may include a first coil with windings that coil (wind) around central axis  94  and a second coil with windings that extend perpendicular to the windings in the first coil. The second coil may, for example, include windings that coil (wind) around axis  96  (e.g., a ring-shaped axis that loops around central axis  94  and lies within the X-Y plane). The windings in the first and second coils may include conductive wire (e.g., copper wire), conductive traces, or any other desired conductive material. 
     Coil structures  44  may include ferrite structures such as ferrite structures  86 . Ferrite structures  86  may include ferrite shield structures that help to electromagnetically shield coil structures  44  from other components in device  10 . If desired, ferrite structures  86  may additionally or alternatively include one or more ferrite cores for the windings in coil structures  44  (e.g., the windings in coil structures  44  may be wound around the ferrite core(s)). Ferrite cores in coil structures  44  may help to maximize the wireless charging efficiency for device  10 . 
     In general, the volume of antenna  40  may be proportional to the efficiency bandwidth of the antenna. While it may be desirable to maximize the volume and thus the efficiency bandwidth of antenna  40 , if care is not taken, the small size of device  10  may serve to limit the efficiency bandwidth of antenna  40 . In order to increase the effective volume of antenna  40  and thus the efficiency bandwidth of antenna  40 , ground traces  90  on sensor board  88  may be used to form part of the antenna ground for antenna  40 . 
     When ground traces  90  are used to form part of the antenna ground for antenna  40 , radio-frequency signals conveyed by antenna resonating element  82  may induce currents on coil structures  44  (e.g., due to the close proximity of coil structures  44  to sensor board  88  and antenna resonating element  82 ). Ferrite structures  86  may block the currents induced on coil structures  44 , which may introduce signal losses that limit the overall antenna efficiency for antenna  40 . If desired, antenna grounding ring structures may be used to allow antenna  40  to include ground traces  90  without introducing losses associated with coil structures  44 . 
       FIG. 5  is a cross-sectional side view showing how antenna grounding ring structures may be used to allow antenna  40  to include ground traces  90  without introducing signal losses associated with coil structures  44  (e.g., within region  98  of  FIG. 4 ). As shown in  FIG. 5 , coil structures  44  may receive wireless charging signals  104  through rear housing wall  12 R. Device  10  may include antenna grounding ring structures such as antenna grounding ring structures  106 . Antenna grounding ring structures  106  may follow a ring-shaped path that laterally extends around central axis  94  and sensor board  88 , as shown by arrow  100 . Antenna grounding ring structures  106  may laterally surround sensor board  88  or may surround an opening that overlaps sensor board  88  (e.g., antenna grounding ring structures  106  may have a central opening and sensor board  88  may be mounted within or overlapping the central opening). Antenna grounding ring structures  106  may sometimes be referred to herein as grounding ring structures  106 , antenna grounding structures  106 , or electric field (E) shield  106 . 
     Grounding ring structures  106  may include conductive traces or any other desired conductive materials. If desired, grounding ring structures  106  may include a substrate such as a flexible printed circuit substrate for the conductive traces in grounding ring structures  106 . The inner edge of grounding ring structures  106  may have one or more grounding terminals  108  coupled to ground traces  90  on sensor board  88 . The opposing outer edge of grounding ring structures  106  may overlap antenna resonating element  82 . For example, peripheral region  112  of grounding ring structures  106  may overlap antenna resonating element  82 . 
     While antenna  40  is conveying radio-frequency signals  102  through rear housing wall  12 R, corresponding antenna currents flow along the edges of antenna resonating element  82 . Some of these antenna currents may flow from the inner edge of antenna resonating element  82  and through grounding ring structures  106  to ground traces  90 , as shown by arrows  110 . These antenna currents may be coupled from antenna resonating element  82  onto grounding ring structures  106  via capacitive coupling, for example. If desired, the size of region  112  may be selected to tune the amount of capacitive coupling provided between antenna resonating element  82  and grounding ring structures  106 . 
     Grounding ring structures  106  may form a short path to ground traces  90  other than through coil structures  44 , thereby preventing radio-frequency signals  102  from inducing currents on coil structures  44 . Because currents are not induced on coil structures  44  by radio-frequency signals  102 , there may be negligible or no signal loss due to the presence of ferrite structures  86 , thereby maximizing the antenna efficiency for antenna  40 . In this way, the antenna ground of antenna  40  may be extended to also include grounding ring structures  106  and ground traces  90  (e.g., antenna  40  may include ground traces  90  and grounding ring structures  106 ), thereby maximizing the volume of antenna  40  and thus antenna efficiency, without introducing signal losses due to the presence of ferrite structures  86  in coil structures  44 . 
       FIG. 6  is a bottom-up view of antenna resonating element  82 , grounding ring structures  106 , coil structures  44 , and sensor board  88  (e.g., as taken in the direction of arrow  114  of  FIG. 5 , where rear housing wall  12 R has been omitted for the sake of clarity). As shown in  FIG. 6 , antenna resonating element  82  may laterally extend along a loop-shaped path extending around a central opening  124 . Positive antenna terminal  58  may be coupled to outer edge  130  of antenna resonating element  82  or elsewhere on antenna resonating element  82 . Sensor board  88 , grounding ring structures  106 , and coil structures  44  may overlap opening  124 . 
     Grounding ring structures  106  and coil structures  44  may laterally extend along loop-shaped paths around central axis  94 . Antenna resonating element  82  may lie within a surface that is vertically interposed (e.g., along the Z-axis) between coil structures  44  and antenna resonating element  82 . The conductive material in antenna resonating element  82  may overlap region  112  of grounding ring structures  106  (e.g., inner edge  132  of antenna resonating element  82  may overlap grounding ring structures  106 ). Grounding ring structures  106 , shown in  FIG. 6  as a shaded region extending between outer edge  126  and inner edge  128 , may be coupled to ground traces on sensor board  88  (e.g., ground traces  90  of  FIG. 5 ) at ground terminal  108 . Ground terminal  108  may, for example, short inner edge  128  of grounding ring structures  106  to the ground traces in sensor board  88 . 
     If desired, outer edge  130  of antenna resonating element  82  may be coupled to the antenna ground for antenna  40  via one or more ground terminals  118 . Antenna resonating element  82  may laterally extend along a loop-shaped path. The length  120  of the loop-shaped path from positive antenna feed terminal  58  to ground terminal  118  may be selected to configure antenna  40  to radiate within a first frequency band. For example, length  120  may be selected to be approximately (e.g., within 15% of) one-half of the effective wavelength corresponding to a frequency in the first frequency band (e.g., an effective wavelength that is modified from a free space wavelength by a constant factor based on the dielectric properties of the materials in the vicinity of antenna resonating element  82 ). If desired, one or more harmonic modes (e.g., a third order harmonic) of length  120  may radiate in a second frequency band that is higher than the first frequency band. In one suitable arrangement that is sometimes described herein as an example, the first frequency band may be a cellular low band from 600 MHz to 960 MHz whereas the second frequency band may include a cellular midband and/or a cellular high band extending from about 1710 MHz to 2700 MHz. If desired, other portions of antenna resonating element  82  such as length  122  may also contribute to radiation by antenna  40  in the second frequency band. 
     As shown in  FIG. 6 , while conveying radio-frequency signals (e.g., radio-frequency signals  102  of  FIG. 5 ), corresponding antenna currents I may flow around the edges of antenna resonating element  82 . Antenna currents I may be capacitively coupled onto grounding ring structures  106  (e.g., within region  112 ). Grounding ring structures  106  may short antenna currents I to the ground traces on sensor board  88  via grounding terminal  108  (e.g., without inducing currents on coil structures  44  that introduce signal losses to the antenna). The ground traces on sensor board  88  may, for example, be coupled to other ground structures in the antenna ground for antenna  40  via ground terminal  116 . Sensor board  88  may, for example, have a tail portion  134  that includes ground terminal  116 . 
     The example of  FIG. 6  is merely illustrative. Antenna resonating element  82 , grounding ring structures  106 , coil structures  44 , and sensor board  88  may have other shapes (e.g., rectangular shapes, square shapes, circular shapes, rectangular shapes having curved corners, elliptical shapes, free-form shapes, etc.). For example, outer edge  130  of antenna resonating element  82 , inner edge  132  of antenna resonating element  82 , outer edge  126  of grounding ring structures  106 , inner edge  128  of grounding ring structures  106 , and coil structures  44  may follow any desired curved and/or straight paths. 
       FIG. 7  is a bottom-up view showing how grounding ring structures  106  may include conductive traces on a dielectric substrate. As shown in  FIG. 7 , grounding ring structures  106  may include conductive traces  136  on a dielectric substrate such as substrate  138 . Substrate  138  may be a flexible printed circuit substrate, a rigid printed circuit board, a plastic substrate, or any other desired substrate. Substrate  138  and conductive traces  136  may, for example, follow a ring-shaped path that loops around central axis  94 . If desired, substrate  138  may include an opening  140  that overlaps central axis  94 . Opening  140  may be omitted if desired. 
     Ground terminal  108  may be coupled to the inner edge of conductive traces  136 . Ground terminal  108  may, if desired, include conductive traces (e.g., traces and/or conductive contact pads on substrate  138 ), solder, conductive vias, conductive welds, conductive adhesive, conductive pins, conductive springs, and/or any other desired conductive interconnect structures that couple conductive traces  136  to the ground traces  90  on sensor board  88  ( FIG. 5 ). Grounding ring structures  106  may include multiple ground terminals  108  if desired. 
     In one suitable arrangement, conductive traces for other components such as conductive traces  144  may be patterned onto substrate  138 . Conductive traces  144  may be coupled to sensor electrodes  74  of  FIG. 5  at terminals  142  and may therefore sometimes be referred to herein as sensor traces  144 . Terminals  142  may include conductive traces (e.g., traces and/or conductive contact pads on substrate  138 ), solder, conductive welds, conductive vias, conductive adhesive, conductive pins, conductive springs, and/or any other desired conductive interconnect structures that couple sensor traces  144  to sensor electrodes  74  of  FIG. 5 . 
     Sensor traces  144  may also be coupled to sensor circuitry on sensor board  88  of  FIG. 5  via terminals  146 . Terminals  146  may include conductive traces (e.g., traces and/or conductive contact pads on substrate  138 ), solder, conductive welds, conductive vias, conductive adhesive, conductive pins, conductive springs, and/or any other desired conductive interconnect structures that couple sensor traces  144  to sensor circuitry on sensor board  88  of  FIG. 5 . The sensor circuitry may, for example, include electrocardiogram sensor circuitry that gathers sensor information (e.g., electrocardiogram sensor information) using sensor electrodes  74  ( FIG. 5 ) and sensor traces  144 . 
     This example is merely illustrative and, in general, the sensor board may gather any desired sensor information from any desired sensors (e.g., sensors  92  of  FIG. 5 ) through sensor traces  144  on substrate  138 . Any desired number of sensor traces  144  may be formed on substrate  138 . Substrate  138  may have any desired shape (e.g., any desired shape having any desired number of curved and/or straight edges). 
     In general, the more conductive material that is included in conductive traces  136 , the greater the maximum antenna efficiency for antenna  40 . However, if care is not taken, the conductive material in grounding ring structures  106  may electromagnetically shield coil structures  44  from receiving wireless charging signals (e.g., wireless charging signals  104  of  FIG. 5 ), thereby limiting the overall wireless charging efficiency of device  10 . In order to maximize antenna efficiency without excessively impairing wireless charging efficiency, conductive traces  136  may include multiple concentric ring traces that are separated by gaps on substrate  138 . 
       FIG. 8  is a bottom-up view of grounding ring structures  106  showing how conductive traces  136  may include multiple concentric ring traces that are separated by gaps on substrate  138  (e.g., within region  148  of  FIG. 7 ). 
     As shown in  FIG. 8 , conductive traces  136  in grounding ring structures  106  may include concentric ring-shaped traces  152  that are patterned onto substrate  138  and concentric about central axis  94  of  FIG. 7 . Each ring-shaped trace  152  of  FIG. 8  may be formed from a (curved) segment of conductive traces on substrate  138  that loops around the central axis (e.g., that follow the ring shape of grounding ring structures  106 ). Each ring-shaped trace  152  in grounding ring structures  106  may be separated from one or two adjacent ring-shaped traces  152  by a corresponding gap  158  (e.g., concentric ring-shaped gaps in the conductive material of grounding ring structures  106  that loop around the central axis). The inner-most ring-shaped trace  152  in grounding ring structures  106  may be coupled to ground terminal  108  by conductive trace  150 . Conductive trace  150  and ground terminal  108  may, for example, be formed on a tail of substrate  138  that protrudes into opening  140  such as tail  154 . 
     Gaps  158  may be configured to allow antenna currents at relatively high frequencies such as the frequencies handled by antenna  40  to pass through grounding ring structures  106  to ground terminal  108  in the radial direction, as shown by arrow  164 . At the same time, gaps  158  may be configured to prevent currents at relatively low frequencies such as the frequencies handled by coil structures  44  ( FIGS. 5 and 6 ) from flowing in the radial direction across grounding ring structures  106  (e.g., ring-shaped traces  152  may exhibit a relatively low or short circuit impedance in the radial direction at the frequencies handled by antenna  40  while exhibiting a relatively high or open circuit impedance at the frequencies handled by coil structures  44 ). This may configure grounding ring structures  106  to allow wireless charging signals (e.g., wireless charging signals  104  of  FIG. 5 ) to pass through grounding ring structures  106  without blocking reception of the wireless charging signals at coil structures  44 . 
     Gaps  158  may have width  160  and ring-shaped traces  152  may have width  162  (e.g., measured in the radial direction about the central axis). Widths  160  and  162  may be selected to adjust the frequencies of the currents that face a relatively low or short circuit impedance to ground terminal  108  and the frequencies of the currents that face a relatively high or open circuit across grounding ring structures  106 . Widths  160  and  162  may, for example, be selected to allow currents above 600 MHz (e.g., frequencies of the radio-frequency signals conveyed by antenna  40 ) to flow across gaps  158  to ground terminal  108  while also blocking currents below 1 MHz (e.g., frequencies of the wireless charging signals received by coil structures  44 ) from passing in the radial direction across gaps  158  and grounding ring structures  106 . As examples, widths  160  and  162  may be 20-80 microns, 30-70 microns, 40-60 microns, 10-100 microns, or other dimensions. Width  160  may be equal to width  162  or may be different from width  162 . Each gap  158  may have the same width  160  or different gaps  158  may have different widths. Each ring-shaped trace  152  may have the same width  162  or different ring-shaped traces  152  may have different widths. In this way, grounding ring structures  106  may serve to maximize the volume and efficiency bandwidth of antenna  40  without excessively impairing the wireless charging efficiency of coil structures  44 . 
     Ring-shaped traces  152  may extend continuously around central axis  94  of  FIG. 7  or may, if desired, include one or more splits such as splits  156  of  FIG. 8  that divide the ring-shaped traces  152  about the central axis. Each ring-shaped trace  152  may include one or more splits  156  or, if desired, some ring-shaped traces  152  may be continuous without any splits. In one suitable arrangement as shown in the example of  FIG. 8 , the splits  156  in each ring-shaped trace  152  may be radially aligned with respect to the central axis. Each ring-shaped trace  152  may include any desired number of splits  156 . Splits  156  may serve to prevent the wireless charging signals that pass through grounding ring structures  106  from producing undesirable eddy currents on ring-shaped traces  152 . Ring-shaped traces  152  need not be curved and may follow any desired ring-shaped path around the central axis (e.g., ring-shaped traces  152  may include straight and/or curved segments following the ring-shaped path of grounding ring structures  106  about the central axis). 
       FIG. 9  is a plot of antenna efficiency as a function of frequency for antenna  40  of  FIGS. 2-8 . Curve  166  of  FIG. 9  plots the antenna efficiency of antenna  40  without grounding ring structures  106  (e.g., curve  166  plots the antenna efficiency for antenna  40  in the arrangement of  FIG. 4 ). As shown by curve  166 , antenna  40  may exhibit a relatively low efficiency within the communications band(s) of operation (e.g., communications band(s)  172 ). Communications band(s)  172  may, for example, include the cellular low band from 600 MHz to 960 MHz. This relatively low efficiency may be a result of the radio-frequency signals conveyed by antenna  40  inducing currents on coil structures  44  that are blocked by ferrite structures  86 . 
     Curve  170  plots the antenna efficiency of antenna  40  in the presence of grounding ring structures  106  (e.g., curve  170  plots the antenna efficiency for antenna  40  in the arrangement of  FIGS. 5-8 ). As shown by curve  170 , the presence of grounding ring structures  106  may serve to increase the antenna efficiency for antenna  40  within communications band(s)  172 , as shown by arrow  168  (e.g., by 2-4 dB or more). This relatively high efficiency may be the result antenna currents being shorted to ground traces  90  on sensor board  88  through grounding ring structures  106  ( FIG. 5 ), allowing radio-frequency signals to be conveyed by antenna  40  (e.g., radio-frequency signals  102  of  FIG. 5 ) without incurring signal losses due to the presence of ferrite structures  86 . The example of  FIG. 9  is merely illustrative. Curves  170  and  166  may have any desired shapes and may exhibit one or more efficiency peaks in any desired number of communications bands at any desired frequencies. 
     If desired, grounding ring structures  106  may include one or more conductive wings that increase the amount of electromagnetic coupling between grounding ring structures  106  and antenna resonating element  82 .  FIG. 10  is a bottom-up view showing how grounding ring structures  106  may include one or more conductive wings. 
     As shown in  FIG. 10 , grounding ring structures  106  may include conductive wings such as conductive wings  174 . Conductive wings  174  may be formed from conductive traces formed on substrate  138  around the periphery of conductive traces  136 . Each conductive wing  174  may be separated from conductive traces  136  by gap  178  (e.g., a ring-shaped region that is free from conductive material). Each conductive wing  174  may be coupled to conductive traces  136  by a corresponding conductive bridge (leg)  176  that bridges gap  178 . Conductive wings  174  and, if desired, a portion of conductive traces  136  may overlap antenna resonating element  82  (e.g., to form region  112  of  FIGS. 5 and 6 ). Conductive wings  174  may extend the conductive material of grounding ring structures  106  to increase the amount of overlap between grounding ring structures  106  and the antenna resonating element, thereby increasing the amount of electromagnetic coupling between the grounding ring structures and the antenna resonating element. This may serve to further maximize antenna efficiency (e.g., by further increasing the volume of antenna  40  and providing a greater area for antenna currents on the antenna resonating element to flow to ground terminal  108 ). 
     Conductive traces  136  of  FIG. 10  may include concentric ring-shaped traces that are separated by gaps (e.g., ring-shaped traces  152  and gaps  158  of  FIG. 8 ). If desired, conductive bridges  176  may also be formed from segments of conductive traces on substrate  138  that are separated by gaps (e.g., segments having widths  162  and gaps having widths  160  of  FIG. 8 ). This may configure conductive bridges  176  to pass antenna currents at the frequencies handled by antenna  40  while forming a relatively high or open circuit impedance for currents at the frequencies handled by coil structures  44  ( FIGS. 5 and 6 ). Unlike conductive traces  136  and conductive bridges  176 , conductive wings  174  may each be formed from a single continuous piece of conductive material (e.g., a single solid conductive trace) on substrate  138 , if desired. 
     In the example of  FIG. 10 , grounding ring structures  106  include four conductive wings  174  that are each separated from two adjacent conductive wings  174  by gaps  180  (e.g., grounding ring structures  106  may include a first conductive wing  174  to the upper-left of conductive traces  136 , a second conductive wing  174  to the upper-right of conductive traces  136 , a third conductive wing  174  to the bottom-left of conductive traces  136 , and a fourth conductive wing  174  to the bottom-right of conductive traces  136 ). This is merely illustrative. There may be more than four conductive wings  174  or fewer than four conductive wings  174  if desired. Conductive wings  174  may have any desired shape (e.g., a shape that fills the space on substrate  138  between conductive traces  136  and the edges of substrate  138 , a shape having any desired number of curved and/or straight edges, etc.). Conductive wings  174  need not all have the same shape. Conductive wings  174  may each be the same size or different conductive wings  174  may be different sizes. Each conductive wing  174  may be coupled to conductive structures  136  by multiple conductive bridges  176  if desired. 
       FIG. 11  is a bottom-up view of grounding ring structures  106  in an example where grounding ring structures  106  include two conductive wings  174 . As shown in  FIG. 11 , grounding ring structures  106  may include two conductive wings  174  patterned onto substrate  138  at opposing sides of conductive traces  136 . Conductive wings  174  may be patterned onto substrate  138  at any desired locations around conductive traces  136 . 
     In the examples of  FIGS. 5-8, 10, and 11 , antenna currents from antenna resonating element  82  pass to grounding ring structures  106  via near-field electromagnetic (e.g., capacitive) coupling. This is merely illustrative. If desired, conductive traces  136  and/or conductive wings  174  of grounding ring structures  106  may be electrically (e.g., galvanically) connected to antenna resonating element  82  by conductive interconnect structures. When arranged in this way, the antenna currents may flow over a conductive path to the ground traces on the sensor board that includes the antenna resonating element, grounding ring structures  106 , and the conductive interconnect structures. 
       FIG. 12  is a bottom-up view showing how conductive traces  136  in grounding ring structures  106  may be electrically connected to antenna resonating element  82  ( FIGS. 5-8, 10 , and  11 ) by conductive interconnect structures. As shown in  FIG. 12 , one or more conductive interconnect structures  182  may be coupled to conductive traces  136 . Conductive interconnect structures  182  may be coupled to outer edge of conductive traces  136 , the inner edge of conductive traces  136 , or elsewhere on conductive traces  136 . 
     Conductive interconnect structures  182  may include conductive traces (e.g., traces and/or conductive contact pads on substrate  138 ), solder, conductive vias, conductive welds, conductive adhesive, conductive pins, conductive springs, and/or any other desired conductive interconnect structures that couple conductive traces  136  to the antenna resonating element. When the antenna resonating element is conveying radio-frequency signals, the antenna currents (e.g., antenna currents I of  FIG. 6 ) may flow from the antenna resonating element to conductive traces  136  through conductive interconnect structures  182 . The antenna currents may then flow through conductive traces  136  to the sensor board through ground terminal  108 . Connecting the antenna resonating element to conductive traces  136  in this way may allow the antenna current to easily flow through grounding ring structures  106  to further optimize the antenna efficiency for the antenna, for example. 
     The example of  FIG. 12  is merely illustrative. Conductive traces  136  may be coupled to the antenna resonating element by a single conductive interconnect structure  182 , two conductive interconnect structures  182 , three conductive interconnect structures  182 , more than three conductive interconnect structures  182 , etc. Conductive interconnect structures  182  may be coupled to any desired sides of conductive traces  136 . If desired, conductive interconnect structures  182  may be used to electrically (e.g., galvanically) connect conductive wings  174  of  FIGS. 10 and 11  to conductive traces  136  (e.g., conductive traces  136  of  FIGS. 7, 8, and 10-12  and/or conductive wings  174  of  FIGS. 10 and 11  may be soldered or otherwise (directly) connected to antenna resonating element  82  using conductive interconnect structures  182 ). 
     In another suitable arrangement, antenna resonating element  82  and conductive traces  136  of grounding ring structures  106  may be patterned onto the same substrate.  FIG. 13  is a side view showing how antenna resonating element  82  and conductive traces  136  of grounding ring structures  106  may be patterned onto the same substrate. 
     As shown in  FIG. 13 , antenna resonating element  82  and conductive traces  136  may both be patterned onto surface  185  of substrate  184 . Substrate  184  may be a logic board, a rigid printed circuit board, a flexible printed circuit, a plastic substrate, or any other desired dielectric substrate. Conductive traces  136  and antenna resonating element  82  may, for example, be patterned onto surface  185  using the same LDS process. Coil structures  44  may underly conductive traces  136  on substrate  184 . Coil structures  44  may be pressed against surface  185 , adhered to surface  185 , spaced apart from surface  185 , etc. Substrate  184  may include an opening that overlaps the opening in conductive traces  106  and/or coil structures  44  if desired. 
       FIG. 14  is a bottom-up view showing how antenna resonating element  82  and conductive traces  136  of grounding ring structures  106  may both be patterned onto surface  185  of substrate  184  (e.g., as taken in the direction of arrow  186  of  FIG. 13 ). As shown in  FIG. 14 , conductive traces such as bridging traces  188  may couple inner edge  132  of antenna resonating element  82  to the outer edge of conductive traces  136 . Bridging traces  188  may, for example, be patterned onto surface  185  during the same LDS process as conductive traces  136  and antenna resonating element  82  (e.g., bridging traces  188 , conductive traces  136 , and antenna resonating element  82  may be formed from the same layer of conductive material patterned onto surface  185 ). This may allow antenna resonating element  82  to be electrically (galvanically) connected to conductive traces  136  without using solder or any other conductive interconnect structures (e.g., conductive interconnect structures  182  of  FIG. 12 ). This may serve to reduce the manufacturing complexity and space required in device  10  to connect antenna resonating element  82  to conductive traces  136  and mitigate impedance discontinuities relative to scenarios where conductive interconnect structures  182  are used. 
     Antenna currents I on antenna resonating element  82  may pass through bridging traces  188 , conductive traces  136 , and ground terminal  108  to the sensor board, as shown by arrow  189 . Any desired number of bridging traces  188  may be used to couple any desired sides of conductive traces  136  to antenna resonating element  82  (e.g., one bridging trace  188 , two bridging traces  188  as shown in  FIG. 14 , three bridging traces, more than three bridging traces, etc.). If desired, splits  156  of  FIG. 8  may be formed in the ring-shaped traces in conductive traces  136  of  FIGS. 10-14  to mitigate the production of eddy currents on grounding ring structures  106  by wireless charging signals passing through the rear housing wall. 
     In the example of  FIGS. 8 and 10-14 , conductive traces  136  are shown as including concentric ring-shaped traces  152  ( FIG. 8 ) that are patterned onto substrate  138  and concentric about central axis  94  of  FIG. 7 . This is merely illustrative. Conductive traces  136  may include conductive traces having other patterns or arrangements. For example, conductive traces  136  may include linear traces that extend in a radial direction away from the central axis (e.g., radial/spoke traces that are tightly spaced on a ring-shaped substrate such as substrate  138 ). Radial traces of these type need not be linear and may, if desired, follow any desired path having any desired number of straight and/or curved segments and having any desired straight and/or curved edges (e.g., where the radial traces follow a path that extends from near the central axis radially outwards away from the central axis). Two or more of the radial traces may be coupled together by one or more ring-shaped conductive traces (e.g., ring-shaped traces  152  of  FIG. 8 ) or other segments of conductive traces extending in a tangential direction to the radial traces if desired. Legs  176  are shown in  FIG. 10  and  FIG. 11  as including such radial traces. If desired, conductive traces  136  may include similar radial traces extending outward from central axis  94  in the radial direction (e.g., in an arrangement with wings  174  as shown in  FIGS. 10 and 11  or in an arrangement without wings as shown in  FIGS. 7, 8, and 12-14 ). 
       FIG. 15  is a plot of antenna efficiency as a function of frequency for antenna  40  of  FIGS. 2-8 and 10-14 . Curve  192  of  FIG. 15  plots the antenna efficiency of antenna  40  without wing structures  174  of  FIGS. 10 and 11 . As shown by curve  192 , antenna  40  may exhibit a relatively high efficiency within communications band  190  (e.g., between a lower frequency F 1  such as 600 MHz and a higher frequency F 2  such as 960 MHz). At the same time, antenna  40  may exhibit a relatively low antenna efficiency at frequencies greater than frequency F 2  (e.g., within the cellular midband and/or high band). 
     Curve  194  plots the antenna efficiency of antenna  40  in the presence of conductive wings  174  of  FIGS. 10 and 11 . As shown by curve  168 , conductive wings  174  may increase the amount of coupling between the antenna resonating element and the grounding ring structures, serving to increase the effective antenna volume and thus the antenna efficiency at frequencies greater than frequency F 2  (e.g., within the cellular midband and/or high band) relative to scenarios where conductive wings  174  are omitted. This may allow antenna  40  to convey radio-frequency signals with satisfactory antenna efficiency over a relatively wide range of frequencies (e.g., across the cellular low band, midband, and/or high band). The example of  FIG. 15  is merely illustrative. Curves  192  and  194  may have any desired shapes and may exhibit one or more efficiency peaks in any desired number of communications bands at any desired frequencies. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20190906
Publication Date: 20201215
Grant Date: 20201215
Priority Date: 20190906
Inventors: DA COSTA BRAS LIMA, EDUARDO JORGE
Ruaro, Andrea
PAPANTONIS, DIMITRIOS
NATH, JAYESH
NIU, Jiaxiao
Martinis, Mario
PASCOLINI, MATTIA
PARKER, MICHAEL R.
EHMAN, Rex T.
Assignee: APPLE INC
CPC Classifications: [{"code": "H02J50/12", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/321", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/0081", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/0025", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/0037", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/26", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B5/70", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/26", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/70", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B5/79", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 73746778