PATENT DOCUMENT

Publication Number: US-10199718-B2
Application Number: US-201514822091-A
Country: US
Kind Code: B2

Title: Electronic device antenna feed and return path structures

Abstract:
An antenna may be formed from a peripheral conductive housing structure in an electronic device that is separated from an antenna ground by a gap. An antenna feed may be formed from a metal trace on a flexible printed circuit that spans the gap. The metal trace may have a line segment that joins a wider pad portion of the trace at a junction. A stiffener on the flexible printed circuit may have a protrusion that overlaps the junction. A metal bracket attached to the peripheral housing structure may be soldered to the pad. A metal member with meandering paths may form a return path in the antenna. The meandering path may have parallel segments that extend along an inner surface of the peripheral conductive housing structure to prevent the metal member from rotating when a screw is used to screw the metal member to the peripheral conductive housing structure.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing; 
 a flexible printed circuit having a metal trace that forms a signal line coupled to a solder pad at a junction, wherein the solder pad is wider than the signal line; 
 a stiffener layer that overlaps the junction and at least part of the solder pad; and 
 a metal bracket soldered to the solder pad, wherein the stiffener layer has a lateral surface that extends along a surface of the flexible printed circuit, the stiffener layer comprises a portion with a first lateral width and a protrusion extending from an end of the portion, the protrusion has a second lateral width that is less than the first lateral width, and the protrusion overlaps the junction and the at least part of the solder pad. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the metal bracket has a recess and wherein the protrusion protrudes into the recess. 
     
     
       3. The electronic device defined in  claim 2  wherein the housing comprises a peripheral conductive housing structure and wherein the metal bracket is attached to the peripheral conductive housing structure. 
     
     
       4. The electronic device defined in  claim 3  further comprising a screw that attaches the metal bracket to the peripheral conductive housing structure. 
     
     
       5. The electronic device defined in  claim 4  wherein the peripheral conductive housing structure forms part of an antenna, wherein the screw attaches the metal bracket to the peripheral conductive housing structure at a positive antenna feed terminal, and wherein the metal trace comprises a positive signal line that is coupled to the metal bracket. 
     
     
       6. The electronic device defined in  claim 5  wherein the antenna includes an inverted-F antenna resonating element that is at least partly formed from the peripheral conductive housing structure and includes an antenna ground that is separated from the inverted-F antenna resonating element by a gap. 
     
     
       7. The electronic device defined in  claim 6  further comprising a return path in the antenna formed from a metal member that spans the gap between the peripheral conductive housing structure and the antenna ground. 
     
     
       8. The electronic device defined in  claim 7  wherein the metal member has a meandering path, wherein the electronic device further comprises dielectric on an inner surface of the peripheral conductive housing structure, wherein the meandering path has segments that extend along the peripheral conductive housing structure and that bear against the dielectric to prevent rotation of the metal member, and wherein the metal trace has a pad to which a coaxial cable center conductor is soldered. 
     
     
       9. The electronic device defined in  claim 1 , wherein the metal bracket has a width and the solder pad extends across the width of the metal bracket. 
     
     
       10. An electronic device, comprising:
 a peripheral conductive housing structure; 
 a dielectric layer on an inner surface of the peripheral conductive housing structure; 
 a metal member having a meandering path portion that bears against a surface of the dielectric layer, the dielectric layer being interposed between the inner surface and the meandering path portion; and 
 a screw that screws a terminal of the metal member to the peripheral conductive housing structure, wherein the dielectric layer is configured to prevent rotation of the metal member while the screw is rotated to screw the terminal of the metal member to the peripheral conductive housing structure. 
 
     
     
       11. The electronic device defined in  claim 10  further comprising an antenna formed from the peripheral conductive housing structure and an antenna ground that is separated from the peripheral conductive housing structure by a gap. 
     
     
       12. The electronic device defined in  claim 11  wherein the metal member is coupled between the peripheral conductive housing structure and the antenna ground and spans the gap. 
     
     
       13. The electronic device defined in  claim 12  wherein the metal member has an additional terminal opposite the terminal and wherein the additional terminal is coupled to the antenna ground. 
     
     
       14. The electronic device defined in  claim 13  wherein the meandering path portion comprises a plurality of segments that run along the peripheral conductive housing structure and that bear against the dielectric layer. 
     
     
       15. The electronic device defined in  claim 14  further comprising:
 a flexible printed circuit; 
 a metal bracket coupled to the peripheral conductive housing structure; 
 a metal trace on the flexible printed circuit having a metal line segment that is joined to a solder pad for the metal bracket at a junction; and 
 a stiffener having a protruding portion that protrudes into a recess in the bracket and that overlaps the junction. 
 
     
     
       16. An apparatus, comprising:
 a metal housing wall; 
 a metal member with a meandering path that extends along a first surface of the metal housing wall and that has an end that is screwed to a second surface of the metal housing wall, the second surface being substantially perpendicular to the first surface; 
 a flexible printed circuit; 
 a metal bracket that is screwed into the metal housing wall; and 
 a solder pad on the flexible printed circuit that is soldered to the metal bracket. 
 
     
     
       17. The apparatus defined in  claim 16  further comprising:
 a metal trace on the flexible printed circuit having a metal line segment that is joined to the solder pad for the metal bracket at a junction; and 
 a stiffener on a surface of the flexible printed circuit and having a protruding portion that protrudes into a recess in the bracket. 
 
     
     
       18. The apparatus defined in  claim 17 , wherein the protruding portion of the stiffener overlaps the junction and at least some of the solder pad.

Description:
This application claims the benefit of provisional patent application No. 62/047,547 filed on Sep. 8, 2014, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with electrical paths for carrying signals such as antenna signals. 
     Electronic devices often include wireless circuitry with antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. 
     It can be challenging to form electronic device signal path structures with desired attributes. In some wireless devices, flexible printed circuits are used to carry signals such as antenna signals. Metal members such as brackets can also carry signals. Flexible printed circuits have metal traces on a flexible polymer substrate. If a flexible printed circuit is not adequately supported, stresses may develop that crack the metal traces. This can make flexible printed circuits less reliable than desired for carrying sensitive signals such as antenna signals. Metal members can be difficult to align and install properly. Without proper installation and alignment, an antenna that includes a signal-carrying metal member may not operate satisfactorily. 
     It would therefore be desirable to be able to provide improved signal carrying structures for electronic devices such as electronic devices with antennas. 
     SUMMARY 
     An electronic device may have circuitry such as wireless circuitry. The wireless circuitry may include one or more antennas. An electronic device housing may be formed from conductive structures such as metal. Signal path structures may be used to convey signals between conductive device structures, wireless circuitry, antennas, and other circuitry in an electronic device. The signal path structures may be formed using flexible printed circuits, metal members, and other signal path structures. 
     An antenna may be formed from a peripheral conductive housing structure that is separated from an antenna ground by a gap. An antenna feed may be formed from a metal trace on a flexible printed circuit that spans the gap. The metal trace may have a line segment that joins a wider pad portion of the trace at a junction. A stiffener on the flexible printed circuit may have a protrusion that overlaps the junction to prevent bending stress from cracking the metal line segment in the vicinity of the junction. A metal bracket that is attached to the peripheral housing structure may be soldered to the pad. 
     A metal member with meandering paths may span the gap and may form a return path in the antenna. The length of the meandering path may be adjusted when it is desired to adjust antenna performance during manufacturing. The meandering path may have parallel segments that extend along an inner surface of the peripheral conductive housing structure to prevent the metal member from rotating when a screw is used to screw the metal member to the peripheral conductive housing structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 3  is a top interior view of a portion of an electronic device having an antenna in accordance with an embodiment. 
         FIG. 4  is a top view of an illustrative antenna feed structure in accordance with an embodiment. 
         FIG. 5  is a side view of the antenna feed structure of  FIG. 4  in accordance with an embodiment of the present invention. 
         FIG. 6  is a perspective view of an interior portion of a housing wall and associated metal antenna return path structure in an antenna in accordance with an embodiment. 
         FIG. 7  is a top view of the metal antenna return path structure of  FIG. 6  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with circuitry such as wireless communications circuitry. Signal paths for conveying signals within the circuitry may be formed using metal members, using signal lines in printed circuits, and using other conductive structures. Signal paths such as these may, for example, be used to route signals within wireless circuits such as antennas and may be used to route signals between other electrical structures (e.g., integrated circuits and other electrical components). Configurations in which signal path structures are used in handling antenna signals associated with one or more antennas in electronic device  10  are sometimes described herein as an example. This is merely illustrative. In general, any suitable signals may be conveyed using metal members, signal lines in printed circuits, and other conductive structures in electronic devices such as electronic device  10 . 
     Device  10  may include one or more antennas such as loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. The conductive electronic device structures may include conductive housing structures and internal structures (e.g., brackets, metal members that are formed using techniques such as stamping, machining, laser cutting, etc.), and other conductive electronic device structures. The housing structures may include peripheral structures such as peripheral conductive structures that run around the periphery of an electronic device. The peripheral conductive structure may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for electronic device  10 . Antennas may also be formed using an antenna ground plane formed from conductive housing structures such as metal housing midplate structures and other internal device structures. Rear housing wall structures may be used in forming antenna structures such as an antenna ground. 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wristwatch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a handheld device such as a cellular telephone, a media player, an electronic stylus, or other small portable device. Device  10  may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, or other suitable electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     The rear face of housing  12  may have a planar housing wall. The rear housing wall may be formed from metal with one or more regions that are filled with plastic or other dielectric. Portions of the rear housing wall that are separated by dielectric in this way may be coupled together using conductive structures (e.g., internal conductive structures) and/or may be electrically isolated from each other. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may be mounted on the opposing front face of device  10  from the rear housing wall. Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. 
     Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. A display cover layer such as a layer of clear glass or plastic, a layer of sapphire, a transparent dielectric such as clear ceramic, fused silica, transparent crystalline material, or other materials or combinations of these materials may cover the surface of display  14 . Buttons such as button  24  may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port  26 . 
     Housing  12  may include peripheral housing structures such as structures  16 . Structures  16  may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, structures  16  may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (as an example). Peripheral structures  16  or part of peripheral structures  16  may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ). Peripheral structures  16  may also, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, by curved sidewalls that extend upwards as integral portions of a rear housing wall, etc.). 
     Peripheral housing structures  16  may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, or a peripheral conductive housing member (as examples). Peripheral housing structures  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral housing structures  16 . 
     It is not necessary for peripheral housing structures  16  to have a uniform cross-section. For example, the top portion of peripheral housing structures  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral housing structures  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral housing structures  16  may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral housing structures  16  serve as a bezel for display  14 ), peripheral housing structures  16  may run around the lip of housing  12  (i.e., peripheral housing structures  16  may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, housing  12  may have a conductive rear surface. For example, housing  12  may be formed from a metal such as stainless steel or aluminum. The rear surface of housing  12  may lie in a plane that is parallel to display  14 . In configurations for device  10  in which the rear surface of housing  12  is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  16  as integral portions of the housing structures forming the rear surface of housing  12 . For example, a rear housing wall of device  10  may be formed from a planar metal structure and portions of peripheral housing structures  16  on the sides of housing  12  may be formed as vertically extending integral metal portions of the planar metal structure. Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . The planar rear wall of housing  12  may have one or more, two or more, or three or more portions. 
     Display  14  may include conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. Housing  12  may include internal structures such as metal frame members, a planar housing member (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more parts that is welded or otherwise connected between opposing sides of member  16 ), printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground plane in device  10 , may be located in the center of housing  12  under active area AA of display  14  (e.g., the portion of display  14  that contains a display module for displaying images). 
     In regions such as regions  22  and  20 , openings may be formed within the conductive structures of device  10  (e.g., between peripheral conductive housing structures  16  and opposing conductive ground structures such as conductive housing midplate or rear housing wall structures, a printed circuit board, and conductive electrical components in display  14  and device  10 ). These openings, which may sometimes be referred to as gaps, may be filled with air and/or solid dielectrics such as plastic, glass, ceramic, polymers with fiber filler material (e.g., fiber composites), sapphire, etc. 
     Conductive housing structures and other conductive structures in device  10  such as a midplate, traces on a printed circuit board, display  14 , and conductive electronic components may serve as a ground plane for the antennas in device  10 . The openings in regions  20  and  22  may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element from the ground plane, may contribute to the performance of a parasitic antenna resonating element, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . If desired, the ground plane that is under active area AA of display  14  and/or other metal structures in device  10  may have portions that extend into parts of the ends of device  10  (e.g., the ground may extend towards the dielectric-filled openings in regions  20  and  22 ). 
     In general, device  10  may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device  10  may be located at opposing first and second ends of an elongated device housing (e.g., at ends  20  and  22  of device  10  of  FIG. 1 ), along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of these locations. The arrangement of  FIG. 1  is merely illustrative. 
     Portions of peripheral housing structures  16  may be provided with gap structures. For example, peripheral housing structures  16  may be provided with one or more peripheral gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral housing structures  16  may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide peripheral housing structures  16  into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral housing structures  16  (e.g., in an arrangement with two gaps), three peripheral conductive segments (e.g., in an arrangement with three gaps), four peripheral conductive segments (e.g., in an arrangement with four gaps, etc.). The segments of peripheral conductive housing structures  16  that are formed in this way may form parts of antennas in device  10 . If desired, gaps may extend across the width of the rear wall of housing  12  and may penetrate through the rear wall of housing  12  to divide the rear wall into different portions. Polymer or other dielectric may fill these housing gaps (grooves). 
     In a typical scenario, device  10  may have upper and lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device  10  in region  22 . A lower antenna may, for example, be formed at the lower end of device  10  in region  20 . The antennas may be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme. 
     Antennas in device  10  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc. 
     A schematic diagram showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, MIMO protocols, antenna diversity protocols, etc. 
     Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button  24  of  FIG. 1 ), etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . 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 low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (as examples). Circuitry  38  may handle voice data and non-voice data. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment such as GPS receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include one or more antennas such as antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. 
     An interior top view of an illustrative antenna of the type that may be formed in device  10  is shown in  FIG. 3 . Antenna  40  of  FIG. 3  may be formed at end  20 , end  22 , or other portion of device  10 . The configuration for antenna  40  of  FIG. 3  is based on an inverted-F antenna design with a slot resonating element (i.e., antenna  40  of  FIG. 3  is a hybrid inverted-F slot antenna). This is merely illustrative. Antenna  40  may be any suitable type of antenna. 
     As shown in  FIG. 3 , antenna  40  may be coupled to transceiver circuitry  90 , so that transceiver circuitry  90  may transmit antenna signals through antenna  40  and may receive antenna signals through antenna  40 . 
     Transceiver circuitry  90  may be coupled to antenna  40  using paths such as transmission line path  92 . Transmission line  92  may include positive signal line (path)  94  and ground signal line (path)  96 . Transmission line  92  may be coupled to an antenna feed for antenna  40  that is formed from positive antenna feed terminal  98  and ground antenna feed terminal  100 . Positive signal line  94  may be coupled to positive antenna feed terminal  98  and ground signal line  96  may be coupled to ground antenna feed terminal  100 . If desired, impedance matching circuitry, switching circuitry, filter circuitry, and other circuits may be interposed in the path between transceiver circuitry  90  and antenna  40 . 
     Antenna  40  of  FIG. 3  includes inverted-F antenna resonating element  106  and antenna ground  104 . Ground  104  may be formed from metal portions of housing  12  (e.g., portions of the rear wall of housing  12 , a housing midplate, etc.), conductive structures such as display components and other electrical components, ground traces in printed circuits, etc. For example, ground  104  may include portions such as portions  104 ′ that are formed from metal housing walls, a metal band or bezel, or other peripheral conductive housing structures. 
     Antenna resonating element  106  may be formed from conductive structure  108 . Structure  108  may be formed from peripheral conductive housing structure in device  10  (e.g., a segment of structures  16  of  FIG. 1 ) or other conductive structure. Structure  108  may form a main resonating element arm for inverted-F antenna resonating element  106  and may have left and right ends that are separate from ground structure  104 ′ by peripheral gaps  18 . 
     Conductive structure  108  may have long and short branches (to the opposing sides of the antenna feed in the orientation of  FIG. 3 ) that support respective lower and higher frequency antenna resonances (e.g., low band and mid-band resonances). Inverted-F antennas that have opposing branches such as these may sometimes be referred to as T antennas or multi-branch inverted-F antennas. 
     Dielectric  114  may form a gap that separates structure  108  from ground  104 . The shape of the dielectric gap associated with dielectric  114  may form a slot antenna resonating element (i.e., the conductive structures surrounding dielectric  114  may form a slot antenna). The slot antenna resonating element may support an antenna resonance at higher frequencies (e.g., a high band resonance). Higher frequency antenna performance may also be supported by harmonics of the lower-frequency resonances associated with the longer and shorter branches of structure  108 . 
     One or more electrical components such as component  102  may span dielectric gap  114 . Components  102  may include resistors, capacitors, inductors, switches and other structures to provide tuning capabilities, etc. Components  102  may be used to tune the performance of antenna  40  dynamically during antenna operation and/or may include fixed components. 
     Return path  110  may be coupled between the main inverted-F resonating element arm formed from structure  108  and antenna ground  104  in parallel with the antenna feed formed by feed terminals  98  and  100 . Return path  110  may be formed from a metal member having opposing first and second ends. In the example of  FIG. 3 , return path  110  is formed from a metal structure that has a first end with a terminal  120  coupled to structure  108  of inverted-F antenna resonating element  106  (e.g., on a housing sidewall or other peripheral conductive structure) and has a second end with a terminal  122  coupled to antenna ground  104 . Return path  110  may have other shapes and sizes, as illustrated, for example, by dashed line  110 ′ and illustrative terminal  122 ′. 
       FIG. 4  is a top view of illustrative structures that may be used in forming an antenna feed connection for antenna  40  of  FIG. 3 . Coaxial cable  92  may form a transmission line path that is coupled between transceiver circuitry  90  and the antenna feed for antenna  40 . An outer ground path conductor in the coaxial cable may be coupled to antenna ground  104  at ground terminal  100  (see, e.g., terminal  100  of  FIG. 3 ). Solder or other conductive material may be used in coupling the ground line in cable  92  to ground  104 . The coaxial cable may also have a positive inner conductor such as conductor  94 - 1 . Conductor  94 - 1  may be soldered to solder pad  94 - 2  on flexible printed circuit  202  using solder  200 . 
     Solder pad  94 - 2  may form part of a metal trace on flexible printed circuit  202  that couples positive signal line  94 - 1  to peripheral conductive housing structure  108 . The metal trace may be formed from copper or other metal. The metal trace may include pad  94 - 2 , line  94 - 3 , line  94 - 4 , and solder pad  94 - 6 . Metal bracket  126  may have a horizontal portion such as portion  126 - 1  that is soldered to solder pad  94 - 6  and an integral vertical portion such as portion  126 - 2  that lies parallel to the inner surface of structure  108  (e.g., a peripheral conductive housing structure such as a sidewall in housing  12 ). Metal screw  128  may be used to mechanically attach and electrically couple vertical portion  126 - 2  of metal bracket  126  to structure  108 . 
     Flexible printed circuit  202  has a flexible substrate such as substrate  132 . Substrate  132  may be, for example, a flexible polymer layer such as a sheet of polyimide. To ensure that flexible printed circuit  202  has sufficient stiffness to resist damage, the upper surface of substrate  132  may be covered with a stiffener such as stiffener  124 . Stiffener  124  may be formed from a rigid layer of polymer (e.g., a relatively thick polyimide layer) or other suitable structure for locally enhancing the stiffness of flexible printed circuit  202 . 
     Stiffener  124  may have a portion such as rectangular portion  124 - 1  that covers metal trace segment  94 - 4  and a protruding portion such as protrusion  124 - 2 . Bracket  126  may include recess  204 . Recess  204  may have a shape that accommodates protrusion  124 - 2 . For example, protrusion  124 - 2  may have an elongated shape with a rounded tip and recess  204  may have a correspondingly rounded opening that receives the rounded tip. Shapes without rounded edges may also be used, if desired. 
     Gap  206  separates protrusion  124 - 2  from the edge of recess  204  in bracket  126 . In this region, flexible printed circuit substrate  132  is not locally stiffened by overlapping stiffener structures. Accordingly, the metal of pad  94 - 6  in gap  206  has the potential to develop cracks during use of device  10  (e.g., when device  10  experiences stresses during a drop event, etc.). Nevertheless, the amount of material in pad  94 - 6  that spans gap  206  is considerably larger than the amount of material associated with metal trace segment  94 - 4  on substrate  132  at junction  94 - 5  between metal trace segment  94 - 4  and pad  94 - 6 . Metal trace segment  94 - 4  is relatively narrow. Pad  94 - 6  is wider than trace  94 - 4 . The metal trace portion at junction  94 - 5  may be sensitive to bending stress and potential stress-induced cracks, due to the relatively narrow width of metal trace segment  94 - 4 . With the arrangement of  FIG. 4 , the metal trace at junction  94 - 5  is covered by stiffener protrusion  124 - 2  and is therefore protected from bending stress. The arrangement of  FIG. 4  therefore helps shield the sensitive portion of the metal trace (i.e., the portion of the metal at junction  94 - 5  between line  94 - 4  and pad  94 - 6 ) from bending stress and potential crack formation and only exposes the robust portion of the metal trace (i.e., the portion of pad  94 - 6  in gap  206 ) to bending stress. There is more material in portion  94 - 6  overlapping gap  206  than other portions of the metal trace and gap  206  is spatially distributed, so the portion of the trace in gap  206  is less likely to receive concentrated bending stress and, in any event, can experience small amounts of cracking without adversely affecting the reliability of the signal path between pad  94 - 2  and structure  108 . 
       FIG. 5  is a cross-sectional side view of flexible printed circuit  202  of  FIG. 4 . As shown in  FIG. 5 , flexible printed circuit  202  includes substrate  132 . Stiffener  124  includes protrusion  124 - 2 , which overlaps stress-sensitive junction  94 - 5  between relatively narrower trace portion  94 - 4  and wider pad portion  94 - 6  of the metal trace on substrate  132 . Adhesive layer  134  attaches a polymer layer such as coverlay  136  to printed circuit  202  over the metal trace. Adhesive  138  attaches polyimide stiffener layer  124  to the top surface of flexible printed circuit  202  (e.g., to coverlay  136 ). Metal bracket  126  has horizontal portion  126 - 1  and vertical portion  126 - 2 . Horizontal portion  126 - 1  is soldered to pad  94 - 6  using solder  140 . Vertical portion  126 - 2  is attached to structure  108  using screw  128 . Screw  128  may have a threaded shaft such as shaft  130  that is received within a mating threaded hole in structure  108 . The electrical connection formed by bracket portion  126 - 2  and screw  128  form positive antenna feed terminal  98  on resonating element  106 . 
     An illustrative signal path structure that may be used for forming return path  110  is shown in  FIG. 6 . As shown in  FIG. 6 , the return path may be formed from a metal member with a meandering signal path (metal member  110 ). Portion  142  of metal member  110  may screwed into structure  108  (e.g., an upper surface of structure  108 ) at terminal  120  by rotating screw  144  about rotational axis  146 . The shaft of screw  144  may be threaded and may be received within mating threads in a hole in structure  108 . If desired, structure  108  may include a recessed portion such as portion  166  so that screw  144  and portion  142  do not protrude excessively above the surface of structure  108 . 
     Horizontal segment  148  of member  110  couples portion  142  of member  110  to vertical segment  150  of member  110 . Meandering signal paths  154  are formed from a series of parallel segments  152  of member  110  that run horizontally along the inner surface of structure  108  (i.e., parallel to structure  108 , which runs along the peripheral edges of device  10 ). Dielectric  114  may separate metal member  110  from structure  108  (e.g., to prevent undesired shorts). Gaps  158  may separate the horizontal segments of member  110  that form the meandering path portion  154  of member  110 . 
     The length of the signal path in member  110  may be adjusted by adjusting the lengths of the segments of the meandering path  154 , allowing the frequency response of antenna  40  to be adjusted during manufacturing. Horizontal segment  160  of member  110  may couple meandering path portion  154  to portion  162  of member  110 . Portion  162  may be attached to antenna ground  104  using screw  164  at terminal  122 . 
     The presence of laterally extending protruding portions of member  110  such as meandering path segments  156  forms a lever arm that helps prevent undesired movement of member  110  when member  110  is being attached to structure  108  by screw  144 .  FIG. 7  is a top view of the structures of  FIG. 6  when viewed in direction  180 . As shown in  FIG. 7 , when screw  144  is being rotated clockwise about axis  146  in direction  190 , there is a tendency of the head of screw  144  to engage portion  142  of member  110 , thereby rotating member  110  about axis  146 . This could misalign member  110  (e.g., so that subsequent installation of screw  164  at terminal  122  might be difficult or impossible). Due to the presence of segments  156 , rotation of member  110  in direction  190  about axis  146  is prevented. This is because surface  172  of member  110  at tip  174  of segment  156  bears against exposed surface  170  of dielectric coating layer  114  on the inner surface of structure  108 . If desired, other shapes may be used for member  110  that have meandering paths or other conductive portions that protrude laterally (parallel to the edges of device  10 ) along the inner surface of structure  108 . The configuration of  FIG. 7  is merely illustrative. 
     If desired, signal path structures such as the flexible printed circuit structure of  FIGS. 3 and 4  and the metal member of  FIGS. 6 and 7  may be used for carrying antenna signals in other portions of antenna  40  (e.g., portions other than the antenna feed and return path for antenna  40 ) and/or may carry other signals in device  10 . The use of these structures to carry antenna feed signals and antenna return path signals in a hybrid inverted-F slot antenna has been described herein as an example. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20150810
Publication Date: 20190205
Grant Date: 20190205
Priority Date: 20140908
Inventors: KHALIFA, SAMMY M.
LAU, DANIEL
MYERS, SCOTT A.
BESEN, RICHARD A.
STEPHENS, GREGORY N.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/36", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 55438364