PATENT DOCUMENT

Publication Number: US-10249937-B2
Application Number: US-201615257542-A
Country: US
Kind Code: B2

Title: Electronic device antenna with suppressed parasitic resonance

Abstract:
An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include cellular telephone antennas, wireless local area network antennas, antenna structures for receiving satellite navigation system signals, and other antennas. An antenna may have an antenna resonating element such as an inverted-F antenna resonating element. The inverted-F antenna resonating element may have an inverted-F antenna resonating element arm formed from metal traces on a flexible printed circuit. The flexible printed circuit may be soldered to an antenna grounding clip. A screw may attach the clip, a speaker tab, a connector bracket, and other metal structures to a metal device housing that serves as ground for the antenna. The screw may be isolated from the antenna grounding clip and the other metal structures by an insulating structure such as an insulating gasket.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 an inverted-F antenna having an inverted-F antenna resonating element arm and having a grounding clip; 
 a metal housing that serves as antenna ground for the inverted-F antenna; 
 at least one metal structure that is electrically coupled to the metal housing and that forms at least a portion of a return path coupling the inverted-F antenna resonating element arm to the antenna ground; 
 a fastener that presses the grounding clip against the at least one metal structure; and 
 an insulating structure interposed between a portion of the fastener and the grounding clip, wherein the housing comprises aluminum, has an anodized coating in a first region, and has a second region without any of the anodized coating to which the at least one metal structure is electrically coupled. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the insulating structure comprises a polymer structure. 
     
     
       3. The electronic device defined in  claim 2  wherein the polymer structure comprises a coating on the grounding clip. 
     
     
       4. The electronic device defined in  claim 2  wherein the polymer structure comprises a polymer gasket. 
     
     
       5. The electronic device defined in  claim 1  wherein the fastener comprises a screw having a screw head, the insulating structure comprises a polymer member, and the polymer member is interposed between the screw head and the grounding clip. 
     
     
       6. The electronic device defined in  claim 1  wherein the inverted-F antenna is configured to transmit and receive wireless local area network antenna signals. 
     
     
       7. The electronic device defined in  claim 1  wherein the at least one metal structure comprises a speaker grounding tab. 
     
     
       8. The electronic device defined in  claim 7  wherein the at least one metal structure comprises a metal member welded to a connector bracket. 
     
     
       9. The electronic device defined in  claim 8  wherein the at least one metal structure comprises metal traces in a flexible printed circuit. 
     
     
       10. The electronic device defined in  claim 9  wherein the metal traces contact the metal housing in the second region. 
     
     
       11. The electronic device defined in  claim 1  wherein the at least one metal structure comprises a plurality of metal members interposed between the grounding clip and the second region. 
     
     
       12. The electronic device defined in  claim 11  wherein one of the metal members comprises a metal clip. 
     
     
       13. The electronic device defined in  claim 12  wherein the fastener comprises a screw having a head and having a threaded shaft that is received within a threaded hold in the metal housing. 
     
     
       14. The electronic device defined in  claim 13  wherein the insulating structure is interposed between the head and the grounding clip. 
     
     
       15. Apparatus, comprising:
 an antenna having a resonating element arm, an antenna ground, an antenna feed that is coupled between the resonating element arm and the antenna ground, and a return path that is coupled between the resonating element arm and the antenna ground in parallel with the antenna feed; and 
 a metal structure having a screw hole; 
 a coating on the metal structure in the screw hole; 
 conductive structures that form the return path, wherein the conductive structures are shorted to a portion of the metal structure that is not covered by the coating; 
 a screw having a threaded shaft that is received within the screw hole and having a head, wherein the screw presses the conductive structures towards the metal structure; and 
 an insulating gasket that electrically isolates the head from the conductive structures. 
 
     
     
       16. The apparatus defined in  claim 15  wherein the conductive structures include an antenna grounding clip and the insulating gasket is interposed between the head and the antenna grounding clip. 
     
     
       17. The apparatus defined in  claim 16  wherein the metal structure comprises a metal electronic device housing and the coating comprises an oxide coating. 
     
     
       18. An electronic device, comprising:
 an antenna having an antenna ground and having an antenna grounding clip that is coupled to the antenna ground; 
 a metal housing that forms the antenna ground and that has a hole with an insulating coating and a region without the insulating coating; 
 an insulating member; 
 a plurality of conductive structures; and 
 a fastener having a first portion that is received within the hole and having a second portion that is electrically isolated from the antenna grounding clip by the insulating member and that presses the antenna grounding clip against the plurality of conductive structures to short the antenna grounding clip to the region without the insulating coating through the plurality of conductive structures. 
 
     
     
       19. The electronic device defined in  claim 18  further comprising:
 a display mounted in the housing; and 
 a speaker mounted to the housing using a speaker grounding tab that forms one of the plurality of conductive structures, wherein the antenna comprises a wireless local area network antenna.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless communications circuitry. For example, cellular telephones, computers, and other devices often contain antennas and wireless transceivers for supporting wireless communications. 
     It can be challenging to incorporate wireless communications circuitry into electronic devices. If care is not taken, a device may be made overly large to accommodate wireless circuitry or wireless performance may not be satisfactory. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include cellular telephone antennas, wireless local area network antennas, antenna structures for receiving satellite navigation system signals, and other antennas. 
     An antenna may have an antenna resonating element such as an inverted-F antenna resonating element. The inverted-F antenna resonating element may have an inverted-F antenna resonating element arm formed from metal traces on a flexible printed circuit. The flexible printed circuit may be soldered to an antenna grounding clip. A screw may attach the clip, a speaker grounding tab, a connector grounding bracket, and other metal structures to a metal device housing that serves as an antenna ground for the antenna. 
     The clip, speaker grounding tab, connector grounding bracket, and other metal structures may form a return path in the antenna. The return path may be coupled between the resonating element arm and the antenna ground in parallel with an antenna feed. The screw may be isolated from the antenna grounding clip and the other metal structures by an insulating structure such as an insulating gasket. The insulating structure may be used to prevent formation of an undesired parasitic antenna path through the screw to the antenna ground that could degrade antenna performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment. 
         FIG. 3  is a diagram of an illustrative transceiver circuit and antenna in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative antenna in accordance with an embodiment. 
         FIG. 5  is a top view of an illustrative electronic device with an antenna in accordance with an embodiment. 
         FIG. 6  is a top view of an illustrative antenna for an electronic device in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative grounding arrangement for an electronic device antenna in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include cellular telephone antennas, wireless local area network antennas (e.g., WiFi® antennas at 2.4 GHz and 5 GHz and other suitable wireless local area network antennas), satellite navigation system signals, millimeter wave communications, and near-field communications 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 cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     As shown in  FIG. 1 , device  10  may include a display such as display  14 . Display  14  may be mounted in a housing such as housing  12 . For example, device  10  may have opposing front and rear faces and display  14  may be mounted in housing  12  so that display  14  covers the front face of device  10  as shown in  FIG. 1 . 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.). If desired, different portions of housing  12  may be formed from different materials. For example, housing sidewalls may be formed from metal and some or all of the rear wall of housing  12  may be formed from a dielectric such as plastic, glass, ceramic, sapphire, etc. Dielectric rear housing wall materials such as these may, if desired, by laminated with metal plates and/or other metal structures to enhance the strength of the rear housing wall (as an example). 
     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 include an array of pixels formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma pixels, an array of organic light-emitting diode pixels, an array of electrowetting pixels, or pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, sapphire, or other transparent dielectric. Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . Buttons such as button  16  may also be formed from capacitive touch sensors, light-based touch sensors, or other structures that can operate through the display cover layer without forming an opening. 
     If desired, an opening may be formed in the display cover layer to accommodate a port such as speaker port  18 . Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.). Openings in housing  12  may also be formed for audio components such as a speaker and/or a microphone. Dielectric-filled openings  20  such as plastic-filled openings may be formed in metal portions of housing  12  such as in metal sidewall structures (e.g., to serve as antenna windows and/or to serve as gaps that separate portions of antennas from each other). Openings such as opening  20  of  FIG. 1  may extend across the rear wall of housing  12 . 
     Antennas may be mounted in housing  12 . If desired, some of the antennas may be mounted under dielectric portions of device  10  (e.g., portions of the display cover layer, portions of a plastic antenna window in a metal housing sidewall portion of housing  12 , etc.). Antennas may also be formed from metal portions of housing  12 . 
     To avoid disrupting communications when an external object such as a human hand or other body part of a user blocks one or more antennas, antennas may be mounted at multiple locations in housing  12 . Sensor data such as proximity sensor data, real-time antenna impedance measurements, signal quality measurements such as received signal strength information, and other data may be used in determining when one or more antennas is being adversely affected due to the orientation of housing  12 , blockage by a user&#39;s hand or other external object, or other environmental factors. Device  10  can then switch one or more replacement antennas into use in place of the antennas that are being adversely affected. 
     Antennas may be mounted at the corners of housing, along the peripheral edges of housing  12 , on the rear of housing  12 , under the display cover layer that is used in covering and protecting display  14  on the front of device  10  (e.g., a glass cover layer, a sapphire cover layer, a plastic cover layer, other dielectric cover layer structures, etc.), under a dielectric window on a rear face of housing  12  or the edge of housing  12 , under a dielectric rear wall of housing  12 , or elsewhere in device  10 . As an example, antennas may be mounted at one or both ends  50  of device  10  (e.g., along the upper and lower edges of housing  12 , at the corners of housing  12 , etc.). 
     A schematic diagram of illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include storage and processing circuitry such as control circuitry  28 . Control circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Control circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOW) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols, millimeter wave communications protocols, etc. 
     Device  10  may include input-output circuitry  44 . Input-output circuitry  44  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers or other components that can detect motion and device orientation relative to the Earth, capacitance sensors, proximity sensors (e.g., a capacitive proximity sensor and/or an infrared proximity sensor), magnetic sensors, and other sensors and input-output components. 
     Input-output circuitry  44  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas  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 communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . 
     Transceiver circuitry  36  may be wireless local area network transceiver circuitry. Transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. 
     Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in frequency ranges such as a communications band from 700 to 960 MHz, a band from 1710 to 2170 MHz, a band from 2300 to 2700 MHz, other bands between 700 and 2700 MHz, higher bands such as LTE bands  42  and  43  (3.4-3.6 GHz), or other cellular telephone communications bands. Circuitry  38  may handle voice data and non-voice data. 
     Wireless communications circuitry  34  may include satellite navigation system circuitry such as Global Positioning System (GPS) receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver  42  are received from a constellation of satellites orbiting the earth. 
     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 WiFi® and Bluetooth® 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. If desired, device  10  may include millimeter wave wireless transceiver circuitry. To enhance signal reception for millimeter wave communications, phased antenna arrays and beam steering techniques may be used (e.g., schemes in which antenna signal phase and/or magnitude for each antenna in an array is adjusted to perform beam steering). Antenna diversity schemes may also be used to ensure that the antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. 
     Antennas  40  in wireless communications circuitry  34  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, monopoles, dipoles, helical antenna structures, Yagi (Yagi-Uda) antenna 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 and another type of antenna may be used in forming a remote wireless link antenna. Dedicated antennas may be used for receiving satellite navigation system signals or, if desired, antennas  40  can be configured to receive both satellite navigation system signals and signals for other communications bands (e.g., wireless local area network signals and/or cellular telephone signals). 
     In configurations for device  10  in which housing  12  has portions formed from metal, openings may be formed in the metal portions to accommodate antennas  40 . For example, openings in a metal housing wall may be used in forming splits (gaps) between resonating element structures and ground structures in cellular telephone antennas. These openings may be filled with a dielectric such as plastic. As shown in  FIG. 1 , for example, portions of plastic-filled openings  20  may run up one or more of the sidewalls of housing  12 . 
     A schematic diagram of a wireless local area network antenna or other antenna  40  coupled to transceiver circuitry  90  (e.g., wireless local area network transceiver  36  and/or other transceiver circuitry  90 ) is shown in  FIG. 3 . As shown in  FIG. 3 , radio-frequency transceiver circuitry  90  may be coupled to antenna feed  102  of antenna  40  using transmission line  92 . Antenna feed  102  may include a positive antenna feed terminal such as positive antenna feed terminal  98  and may have a ground antenna feed terminal such as ground antenna feed terminal  100 . Transmission line  92  may be formed form metal traces on a printed circuit or other conductive structures and may have a positive transmission line signal path such as path  94  that is coupled to terminal  98  and a ground transmission line signal path such as path  96  that is coupled to terminal  100 . Transmission line paths such as path  92  may be used to route antenna signals within device  10 . For example, transmission line paths may be used to couple antenna structures such as one or more antennas in an array of antennas to transceiver circuitry  90 . Transmission lines in device  10  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within transmission line  92  and/or circuits such as these may be incorporated into antenna  40  (e.g., to support antenna tuning, to support operation in desired frequency bands, etc.). 
     Device  10  may contain multiple antennas  40 . The antennas may be used together or one of the antennas may be switched into use while other antenna(s) are switched out of use. If desired, control circuitry  28  may be used to select an optimum antenna to use in device  10  in real time and/or to select an optimum setting for adjustable wireless circuitry associated with one or more of antennas  40 . Antenna adjustments may be made to tune antennas to perform in desired frequency ranges, to perform beam steering with a phased antenna array, and to otherwise optimize antenna performance. Sensors may be incorporated into antennas  40  to gather sensor data in real time that is used in adjusting antennas  40 . 
       FIG. 4  is a diagram of an illustrative antenna that may be used in device  10 . In the example of  FIG. 4 , antenna  40  is an inverted-F antenna. Antenna  40  of  FIG. 4  may be used in forming a wireless local network antenna or other suitable antenna in device  10 . 
     As shown in  FIG. 4 , antenna  40  may include an antenna resonating element such as antenna resonating element  110  and an antenna ground such as antenna ground  112 . Antenna resonating element  110  may have one or more branches such as antenna resonating element arm  116 . Return path  118  (sometimes referred to as a short circuit path) may be coupled between resonating element arm  116  and ground  112 . If desired, return path  118  may include a stack of conductive structures  114  (e.g., brackets, flexible printed circuit traces, etc.). Antenna feed  102  may include positive antenna feed terminal  98  and ground antenna feed terminal  100  and may be coupled between element  110  (e.g., arm  116 ) and ground  112  in parallel with return path  118 . One or more optional components (switches, tunable circuits such as tunable capacitors, tunable inductors, etc.) may be coupled between antenna ground  112  and resonating element arm  116  and may be adjusted to tune antenna  40 . The configuration of  FIG. 4  in which no tunable components are coupled between arm  116  and ground  112  is merely illustrative. 
     Antenna resonating element arm  116  may be separated from ground  112  by dielectric opening  122 . If desired, opening  122  may form a slot antenna element that contributes to the antenna response of antenna  40 . In the example of  FIG. 4 , antenna  40  is an inverted-F antenna that does not include a slot antenna element. 
     Antennas such as antenna  40  of  FIG. 4  (e.g., inverted-F antennas, slot antennas, hybrid inverted-F slot antennas, etc.) and/or other types of antenna (e.g., patch antennas, loop antennas, etc.) may be used in supporting cellular telephone communications, wireless local area network communications (e.g., communications at 2.4 and 5 GHz, etc.) and/or other wireless communications. 
     Screws and other fasteners may, if desired, be used to help couple the conductive structures of antenna  40  to ground  112 . For example, a screw or other fastener may be used to mount a ground portion of antenna  40  in a configuration that shorts the ground portion of antenna  40  to an antenna ground plane. The antenna ground plane may, for example, be formed from a metal housing such as electronic device housing  12 . 
     If care is not taken, the presence of the screws may create an undesired parasitic antenna structure that degrades the performance of antenna  40  (e.g., by creating a parasitic resonating mode with an undesired frequency response). For example, there may be a risk that a screw or other fastener might create an undesired parasitic such as parasitic path (structure)  124  between arm  116  and ground  112  that degrades antenna performance. To minimize or eliminate this possibility, the screw or other fastener that is associated with potential path  124  may be electrically isolated from the other structures of resonating element  110  (e.g., arm  116 , structures  114 , and/or other portions of antenna  40 ). Isolating the screw or other fastener in this way may help ensure that antenna  40  operates satisfactorily. 
     Antennas  40  may be formed from sheet metal parts (e.g., strips of sheet metal embedded in molded plastic or attached to dielectric supports using adhesive, etc.), may be formed from wires, may be formed from portions of conductive housing structures (e.g., metal walls in housing  12 ), and/or may be formed from conductive structures such as metal traces on a printed circuit or other substrate. Printed circuits in device  10  may be rigid printed circuit boards formed from rigid printed circuit board substrate material (e.g., fiberglass-filled epoxy) and/or may be flexible printed circuit boards (e.g., printed circuits formed from sheets of polyimide or other flexible polymer layers). In some configurations, antenna substrates may be formed from other dielectrics (e.g., ceramics, glass, etc.). 
       FIG. 5  is a top view of an illustrative electronic device such as device  10  of  FIG. 1  that includes an antenna. As shown in  FIG. 5 , antenna  40  may be located in the lower right corner  130  of housing  12  (as an example). In this location, antenna  40  may be mounted adjacent to a connector such as connector  134 . Connector  124  may have contacts that mate with corresponding contacts on a cable or other accessory. Connector  134  may have metal parts (e.g., metal supporting and shielding structures, such as brackets  136  and  138 . Fasteners such as screws  142  and  140  may be used to couple portions of connector  134  such as brackets  136  and  138  to housing  12 . This may serve to ground brackets  136  and  138  and thereby may ground portions of connector  134  (e.g., shielding structures in connector  134 ). 
     Device  10  may include electrical components such as component  146 . Component  146  may be, for example, a speaker or other audio component. Component  146  may include sheet metal structures and/or other metal structures. These structures in component  146  may be grounded to housing  12  using speaker grounding tab  148 . Screw  140  may be used to mount grounding tab  148  to housing  12 . 
     Antenna  40  may have conductive structures such as antenna grounding clip  132  (sometimes referred to as an antenna clip, wireless local area network antenna clip, etc.). Antenna grounding structures such as grounding clip  132  may also be coupled to housing  12  using screw  140 . A top view of antenna  40  and screw  140  is shown in  FIG. 6 . As shown in  FIG. 6 , antenna  40  may include metal traces  150  on flexible printed circuit  154  that are patterned to form antenna resonating element  110 . Antenna clip  132  may be formed from a metal member such as a sheet metal member that is attached to device  10  using screw  140  (e.g., so that clip  132  is shorted to the antenna ground formed from housing  12 ). Solder  152  may be used to short ground traces in traces  150  to clip  132 . Return path  118  may be formed from portions of traces  150 , solder  152 , antenna clip  132 , and other conductive structures (see, e.g., structures  114  of  FIG. 5 ) that are coupled to housing  12  in the vicinity of screw  140 . Screw  140  may be electrically isolated from clip  132  so as not to form undesired parasitic path  124  in parallel with return path  118 . 
     A cross-sectional side view of screw  140  and associated structures that are being mounted to housing  12  using screw  140  are shown in  FIG. 7 . As shown in  FIG. 7 , screw  140  may be used to couple connector bracket  138  to housing  12 . Screw  140  may pass through an opening in bracket  138  and may hold bracket  138  against structure  160  (e.g., plastic support structures and/or other structures in device  160  that can support bracket  138 ). Connector clip  138 ′ may be welded to bracket  138  using welds  174 . At lower portion  176  of clip  138 ′, clip  138 ′ may be electrically coupled to housing  12  in region  166  through flexible printed circuit  164 . 
     Flexible printed circuit  164  may have metal traces that supply signals to connector  134  of  FIG. 5  and/or may be associated with other components in device  10 . Flexible printed circuit  164  may be formed from a layer of polyimide or other flexible dielectric substrate material. As shown in  FIG. 7 , flexible printed circuit  164  may have metal traces such as pads  190  and via  192  that electrically couple clip  138 ′ to housing  12  in region  166 . 
     With an arrangement of the type shown in  FIG. 7 , speaker mounting tab  148  ( FIG. 5 ) may be pressed against bracket  138  by downward pressure from screw  140 . This shorts tab  148  to bracket  138 . Antenna grounding clip  150  may be pressed against speaker mounting tab  148  by downward pressure from screw  140  and may be shorted to bracket  138  through tab  148 . The structures of  FIG. 7  thereby ground antenna clip  150  to housing  12  (i.e., clip  150 , tab  148 , clip  138 ′, bracket  138 , traces  190  and  192  in flexible printed circuit  164  form conductive structures  114  of return path  118  of antenna  40  of  FIG. 4 ). 
     Housing  12  may be formed from a metal such as aluminum. The surface of housing  12  may be anodized to form a thin protective anodized coating (e.g., aluminum oxide) such as coating  168 . This protective coating is insulating and may be formed on the inner and outer surfaces of housing  12  including within threaded screw hole  194 . To ensure that traces  190  of flexible printed circuit  164  make satisfactory ohmic contact to housing  12 , anodized coating  168  may be selectively removed in region  166  (e.g., by chemical etching, laser removal, etc.) to expose bare aluminum (or other metal) that forms housing  12 . Screw  140  may have threads  172  that are received by making threads in threaded screw hole  194 . Thread locking compound  170  may be use to help hold screw  140  in place within hole  194 . 
     The arrangement of  FIG. 7  helps ground antenna  40  be forming return path  118  to housing  12 , which serves as antenna ground  112 . If desired, more metal structures or fewer metal structures may be used in forming path  118  between arm  116  of antenna  40  and ground  112 . The configuration of  FIG. 7  is merely illustrative. 
     In some situations, screw  140  may be electrically isolated from housing  12  due to the presence of anodized coating  168  and thread locking compound  170 . In other situations, screw  140  may break through portions of coating  168  and thread locking compound  170 , so that screw  140  is electrically shorted to housing  12 . However, in situations in which screw  140  is not shorted to housing  12  due to the presence of anodized coating  168 , there is a risk that screw  140  may serve as undesired parasitic antenna structure  124  of  FIG. 4 . In this type of scenario, screw  140  may give rise to a parasitic antenna resonance that degrades antenna performance. 
     To ensure that screw  140  does not form undesired parasitic structure  124  of  FIG. 4 , screw  140  may be electrically isolated from antenna  40  by interposing insulating layer  162  between head  140 ′ of screw  140  and antenna grounding clip  132 . Insulating layer  162  may be formed from an injection molded polymer coating on grounding clip  150 , may be formed from a sprayed polymer coating, a dipped polymer coating, or other dielectric coating layer on clip  150 , may be formed from a polymer member, a dielectric gasket, or other insulating member (e.g., a circular ring-shaped dielectric gasket formed from a dielectric such as polyimide or other polymer), or may be formed from other suitable insulating structures. In the absence of an insulating structure between clip  150  and head  140 ′ of screw  140  such as insulating layer  162 , there will be a risk that antenna currents can flow in shaft  140 ″ of screw  140  (i.e., screw  140  may act as undesired parasitic antenna structure  124 ). In the presence of insulating structure such as insulating layer  162 , head  140 ′ and therefore screw  140  will be electrically isolated from clip  150  and will be electrically isolated from the rest of antenna  40  and will therefore not interfere with the operation of antenna  40 . 
     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: 20160906
Publication Date: 20190402
Grant Date: 20190402
Priority Date: 20160906
Inventors: JIN, NANBO
LAKSHMANAN, ANAND
CHENG, CHRISTOPHER T.
TONG, ERICA J.
WANG, HAN
PASCOLINI, MATTIA
MYERS, SCOTT A.
GAO, XU
DINH, RICHARD H.
TAN, TANG YEW
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/328", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2291", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/328", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 61281516