PATENT DOCUMENT

Publication Number: US-9450292-B2
Application Number: US-201313910550-A
Country: US
Kind Code: B2

Title: Cavity antennas with flexible printed circuits

Abstract:
An antenna with a curved shape may be mounted behind a curved antenna window. The antenna may have an antenna resonating element such as an inverted-F antenna resonating element and may have an antenna ground. The antenna resonating element may be formed from patterned metal traces on a flexible printed circuit. The flexible printed circuit may have ground traces that run along a peripheral edge of the flexible printed circuit. The antenna ground may be formed from a metal can with walls surrounding a cavity having an opening. The metal can may have a lip formed from bent portions of the walls. The flexible printed circuit may be soldered to the lip so that the ground traces are shorted to the can. A cable connector may be mounted on a bent tab in the flexible printed circuit that extends through a notch in the lip.

Claims:
What is claimed is: 
     
       1. A cavity antenna having an antenna resonating element and an antenna ground, comprising:
 a flexible printed circuit having metal traces that form the antenna resonating element and having peripheral ground traces, wherein the antenna resonating element comprises an inverted-F antenna resonating element; and 
 a metal can that forms the antenna ground and that forms a cavity with an opening, wherein the metal can has a lip that surrounds the opening and the flexible printed circuit is mounted over the opening so that the peripheral ground traces are coupled to the lip, and the lip comprises an outwardly bent portion of the metal can. 
 
     
     
       2. The cavity antenna defined in  claim 1  wherein the lip has a notch. 
     
     
       3. The cavity antenna defined in  claim 2  wherein the flexible printed circuit has a tab that passes through the notch. 
     
     
       4. The cavity antenna defined in  claim 3  further comprising solder that solders the tab to the metal can. 
     
     
       5. The cavity antenna defined in  claim 4  further comprising a cable connector on the tab. 
     
     
       6. The cavity antenna defined in  claim 5  wherein the tab has a right angle bend. 
     
     
       7. The cavity antenna defined in  claim 6  wherein the peripheral ground traces are soldered to the lip. 
     
     
       8. The cavity antenna defined in  claim 7  wherein the flexible printed circuit is bowed and the lip has a curved shape that mates with the flexible printed circuit. 
     
     
       9. An electronic device, comprising:
 a metal housing; 
 a curved antenna window in the metal housing; and 
 an antenna formed from a metal can and metal traces on a flexible printed circuit, wherein the metal traces on the flexible printed circuit form an antenna resonating element for the antenna, the metal can defines a cavity with an opening and has a lip that surrounds the opening, the lip has a notch, the flexible printed circuit has a bent tab portion that passes through the notch, the flexible printed circuit is mounted to the lip and covers the opening, and the flexible printed circuit is bowed outwards to create a curved surface that matches the curved antenna window. 
 
     
     
       10. The electronic device defined in  claim 9  wherein the lip is formed from bent portions of the metal can. 
     
     
       11. The electronic device defined in  claim 10  wherein the flexible printed circuit contains peripheral ground traces that run along a peripheral edge of the flexible printed circuit and that are soldered to the lip. 
     
     
       12. The electronic device defined in  claim 11  wherein the flexible printed circuit has an integral tail, the electronic device further comprising a cable coupled to the integral tail. 
     
     
       13. The electronic device defined in  claim 10  further comprising a coaxial cable connector on the flexible printed circuit. 
     
     
       14. A cavity antenna having an antenna resonating element and an antenna ground, the cavity antenna comprising:
 a metal can that forms the antenna ground, wherein the metal can has walls that surround a cavity with an opening, a lip that surrounds the opening, and a notch that is formed in the lip; and 
 a flexible printed circuit having metal traces that form the antenna resonating element and having a tab with a bent tab portion, wherein the bent tab portion passes through the notch and is soldered to one of the walls. 
 
     
     
       15. The cavity antenna defined in  claim 14  further comprising a cable connector on the tab. 
     
     
       16. The cavity antenna defined in  claim 15  further comprising peripheral ground traces that run along a peripheral edge of the flexible printed circuit, the lip is formed from bent portions of the walls, and the peripheral ground traces are soldered to the lip. 
     
     
       17. The cavity antenna defined in  claim 16  further comprising an electrical component that is soldered to the flexible printed circuit. 
     
     
       18. The cavity antenna defined in  claim 14  wherein the metal can has four side walls and a rear wall, the opening opposes the rear wall, and the flexible printed circuit completely covers the opening.

Description:
BACKGROUND 
     This relates generally to electronic devices, and, more particularly, to antennas in electronic devices. 
     Electronic devices such as portable computers and handheld electronic devices are often provided with wireless communications capabilities. For example, electronic devices may have wireless communications circuitry to communicate using cellular telephone bands and to support communications with satellite navigation systems and wireless local area networks. 
     It can be difficult to incorporate antennas and other electrical components successfully into an electronic device. Some electronic devices are manufactured with small form factors, so space for components is limited. In many electronic devices, the presence of conductive structures can influence the performance of electronic components, further restricting potential mounting arrangements for components such as antennas. 
     It would therefore be desirable to be able to provide improved electronic device antennas. 
     SUMMARY 
     An electronic device may be provided with a housing. An antenna window may be formed in the housing. The housing and the antenna window may have matching curved shapes. 
     An antenna with a curved shape that matches the curved shape of the antenna window may be mounted behind the antenna window. The antenna may have an antenna resonating element such as an inverted-F antenna resonating element and may have an antenna ground. The antenna resonating element may be formed from patterned metal traces on a flexible printed circuit. The antenna ground may be formed from a metal can that defines a cavity with an opening. 
     The flexible printed circuit may have ground traces that run along a peripheral edge of the flexible printed circuit. The metal can may have walls that surround a cavity with an opening. The metal can may have a lip formed from bent portions of the walls. The flexible printed circuit may cover the opening. 
     The flexible printed circuit may be bowed outwards away from the cavity so that the flexible printed circuit has a curved surface that matches the curved shape of the antenna window. 
     The flexible printed circuit may be soldered to the lip so that the ground traces are shorted to the can. A cable connector may be mounted on a bent tab in the flexible printed circuit. The lip may have a notch. The bent tab may pass through the notch. Solder may be used to attach the bent tab to one of the walls of the metal can. A cable connector may be soldered to the tab. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer of the type that may be provided with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a handheld electronic device of the type that may be provided with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 3  is a perspective view of an illustrative electronic device such as a tablet computer of the type that may be provided with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 4  is a perspective view of an illustrative electronic device such as a computer display of the type that may be provided with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 5  is a perspective view of an electronic device such as a computer, set-top box, or wireless router that may be provided with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of antenna structures and associated circuitry in an electronic device in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram of antenna structures based on an inverted-F antenna design of the type that may be used in an electronic device in accordance with an embodiment of the present invention. 
         FIG. 8  is a perspective view of a portion of a curved housing wall with a curved antenna window in an electronic device in accordance with an embodiment of the present invention. 
         FIG. 9  is a perspective view of an illustrative cavity antenna of the type that may be mounted behind an antenna window such as the antenna window of  FIG. 8  in accordance with an embodiment of the present invention. 
         FIG. 10  is a cross-sectional side view of an illustrative cavity antenna mounted under a curved antenna window in an electronic device with a curved housing wall in accordance with an embodiment of the present invention. 
         FIG. 11  is an exploded perspective view of an illustrative flexible printed circuit containing antenna traces and an associated metal antenna cavity structure with a notched lip in accordance with an embodiment of the present invention. 
         FIG. 12  is a perspective view of a flexible printed circuit and associated antenna cavity structure that have been assembled to form an antenna that can be coupled to radio-frequency transceiver circuitry using a transmission line such as a transmission line based on a cable in accordance with an embodiment of the present invention. 
         FIG. 13  is a cross-sectional side view of an illustrative microstrip transmission line that may be used in handling radio-frequency antenna signals in accordance with an embodiment of the present invention. 
         FIG. 14  is a cross-sectional side view of an illustrative stripline transmission line that may be used in handling radio-frequency antenna signals in accordance with an embodiment of the present invention. 
         FIG. 15  is a top view of a flexible printed circuit in a flattened state showing how the flexible printed circuit may be provided with protruding tabs that can be bent downwards to couple the flexible printed circuit to a metal can that forms an antenna cavity in accordance with an embodiment of the present invention. 
         FIG. 16  is a top view of a flexible printed circuit for an antenna in which the flexible printed circuit has a tail portion for use in securing a transmission line such as a coaxial cable in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may include antennas. The antennas may be used to support wireless communications such as cellular telephone communications, wireless local area network communications, peer-to-peer communications, satellite navigation system communications, and other wireless communications. Illustrative electronic devices that may be provided with antennas are shown in  FIGS. 1, 2, 3, 4, and 5 . 
       FIG. 1  shows how electronic device  10  may have the shape of a laptop computer having upper housing  12 A and lower housing  12 B with components such as keyboard  16  and touchpad  18 . Device  10  may have hinge structures  20  that allow upper housing  12 A to rotate in directions  22  about rotational axis  24  relative to lower housing  12 B. Display  14  may be mounted in upper housing  12 A. Upper housing  12 A, which may sometimes referred to as a display housing or lid, may be placed in a closed position by rotating upper housing  12 A towards lower housing  12 B about rotational axis  24 . 
       FIG. 2  shows how electronic device  10  may be a handheld device such as a cellular telephone, music player, gaming device, navigation unit, or other compact device. In this type of configuration for device  10 , housing  12  may have opposing front and rear surfaces. Display  14  may be mounted on a front face of housing  12 . Display  14  may, if desired, have openings for components such as button  26 . Openings may also be formed in display  14  to accommodate a speaker port (see, e.g., speaker port  28  of  FIG. 2 ). 
       FIG. 3  shows how electronic device  10  may be a tablet computer. In electronic device  10  of  FIG. 3 , housing  12  may have opposing planar front and rear surfaces. Display  14  may be mounted on the front surface of housing  12 . As shown in  FIG. 3 , display  14  may have an opening to accommodate button  26  (as an example). 
       FIG. 4  shows how electronic device  10  may be a computer display or a computer that has been integrated into a computer display. With this type of arrangement, housing  12  for device  10  may be mounted on a support structure such as stand  27 . Display  14  may be mounted on a front face of housing  12 . 
       FIG. 5  shows how electronic device  10  may be a computer, a wireless router, a set-top box, or other electrical equipment. Housing  12  may have a cylindrical shape with curved sidewalls and planar upper and lower surfaces, may have a rectangular box shape (e.g., a box shape with rounded corners), and/or may have other shapes with curved and/or planar housing walls. 
     Sensors, input-output devices, buttons, and other components such as connectors  30  may be mounted in housing  12 . Connectors  30  may include audio jacks or other audio connectors, Universal Serial Bus connectors, Ethernet connectors, and other digital data port connectors, removable media connectors, and other connectors. 
     Antenna structures  32  (e.g., one or more antennas) may be mounted within the interior of device  10  (e.g., in the interior of housing  12 ). If desired, antenna  32  may have an antenna cavity. A conductive antenna ground structure with walls may surround and define a dielectric volume (sometimes referred to as an antenna cavity). The conductive structures that define the antenna cavity may be formed from a metal can or other conductive structures. 
     Antennas such as antenna  32  of  FIG. 5  that include a metal can for forming an antenna cavity may sometimes be referred to as cavity antennas. Cavity antenna  32  may face outwards from the interior of device  10 . In configurations of the type shown in  FIG. 5  in which housing  12  has one or more curved surfaces, antenna  32  may have a corresponding curved portion that is mounted against the curved housing surface. This helps minimize the amount of space that is consumed by the antenna within the interior of device  10  while enhancing antenna efficiency by locating the antenna in a prominent position. 
     Electronic devices such as electronic devices  10  of  FIG. 5  and electronic devices  10  of  FIGS. 1, 2, 3, and 4  may each be provided with one or more antennas such as antenna  32 . The configuration of  FIG. 5  is merely illustrative. 
     The configurations for device  10  that are shown in  FIGS. 1, 2, 3, 4, and 5  are provided as examples. In general, electronic device  10  may be 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 wrist device, a pendant device, a headphone or earpiece device, 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 is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other wireless electronic equipment. 
     Housing  12  of device  10 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal (e.g., machined aluminum, stainless steel, or other metals), other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Display  14  may be a touch sensitive display that includes a touch sensor or may be insensitive to touch. Touch sensors for display  14  may be formed from an array of capacitive touch sensor electrodes, a resistive touch array, touch sensor structures based on acoustic touch, optical touch, or force-based touch technologies, or other suitable touch sensor components. Display  14  for device  10  may include display pixels formed from liquid crystal display (LCD) components, organic light-emitting diode components, or other suitable image pixel structures. 
     A schematic diagram of an illustrative configuration that may be used for electronic device  10  is shown in  FIG. 6 . As shown in  FIG. 6 , electronic device  10  may include control circuitry  46 , input-output devices  48 , and wireless circuitry  54 . 
     Control circuitry  46  may include storage and processing circuitry for controlling the operation of device  10 . Control circuitry  46  may, for example, 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. Control circuitry  46  may include processing circuitry based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc. 
     Control circuitry  46  may be used to run software on device  10 , such as operating system software and application software. Using this software, control circuitry  46  may, for example, transmit and receive wireless data, tune antennas to cover communications bands of interest, and perform other functions related to the operation of device  10 . 
     Input-output devices  48  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 circuitry in devices  48  may include communications circuitry such as wired communications circuitry. 
     Input-output devices  48  may include input-output components with which a user can control the operation of device  10 . A user may, for example, supply commands through input-output devices  48  and may receive status information and other output from device  10  using the output resources of input-output devices  48 . 
     Input-output devices  48  may include sensors and status indicators such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, and light-emitting diodes and other components for gathering information about the environment in which device  10  is operating and providing information to a user of device  10  about the status of device  10 . Audio components in devices  48  may include speakers and tone generators for presenting sound to a user of device  10  and microphones for gathering user audio input. Devices  48  may include one or more displays such as display  14 . Displays may be used to present images for a user such as text, video, and still images. Sensors in devices  48  may include a touch sensor array that is formed as one of the layers in display  14 . During operation, user input may be gathered using buttons and other input-output components in devices  48  such as touch pad sensors, buttons, joysticks, click wheels, scrolling wheels, touch sensors such as a touch sensor array in a touch screen display or a touch pad, key pads, keyboards, vibrators, cameras, and other input-output components. 
     Device  10  may use wireless circuitry  54  to communicate over one or more wireless communications bands. Wireless communications circuitry  54  may include radio-frequency (RF) transceiver circuitry such as transceiver circuitry  44  that is formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas such as antenna structures  32 , and other circuitry for handling RF wireless signals. Transceiver circuitry  44  may communicate with control circuitry  46  via path  50 . Transceiver circuitry  44  may be used for handling cellular telephone communications, wireless local area network signals, and satellite navigation system signals such as signals at 1575 MHz from satellites associated with the Global Positioning System. Transceiver circuitry  44  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications or other wireless local area network communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  44  may include cellular telephone transceiver circuitry for handling wireless communications in cellular telephone bands such as the bands in the range of 700 MHz to 2.7 GHz (as examples). 
     Wireless communications circuitry  54  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  54  may include wireless circuitry for receiving radio and television signals, paging circuits, etc. 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  54  may also include circuitry for handing near field communications. 
     Wireless communications circuitry  54  may include antenna structures  32 . Antenna structures  32  may include one or more antennas. Antenna structures  32  may include inverted-F antennas, slot antennas, patch antennas, loop antennas, monopoles, dipoles, single-band antennas, dual-band antennas, antennas that cover more than two bands, cavity antennas, or other suitable antennas. 
     To provide antenna structures  32  with the ability to cover communications frequencies of interest, antenna structures  32  may be provided with impedance matching circuitry, filter circuitry, and/or adjustable antenna circuitry. These circuits may be adjusted using control signals from control circuitry  46  that are provided to the circuits over one or more paths such as path  52 . 
     Transceiver circuitry  44  may be coupled to antenna structures  32  by signal paths such as signal path  34 . Signal path  34  may include one or more transmission lines. As an example, signal path  34  of  FIG. 6  may be a transmission line having a positive signal conductor such as line  40  and a ground signal conductor such as line  42 . Lines  40  and  42  may form parts of a coaxial cable, a stripline transmission line, or a microstrip transmission line (as examples). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures  32  to the impedance of transmission line  34 . 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 structures  32  and/or tunable circuitry in antenna structures  32 . 
     Transmission line  34  may be coupled to antenna feed structures associated with antenna structures  32 . As an example, antenna structures  32  may form an inverted-F antenna having an antenna feed with a positive antenna feed terminal such as terminal  36  and a ground antenna feed terminal such as ground antenna feed terminal  38 . Positive transmission line conductor  40  may be coupled to positive antenna feed terminal  36  and ground transmission line conductor  42  may be coupled to ground antenna feed terminal  38 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 6  is merely illustrative. 
       FIG. 7  is a diagram of an illustrative inverted-F antenna of the type that may be used in forming antenna  32  of  FIG. 6 . If desired, other types of antenna may be used in forming antenna  32 . The use of an inverted-F antenna design for antenna  32  is merely an example. 
     As shown in  FIG. 7 , antenna  32  may include inverted-F antenna resonating element  54  and antenna ground  56 . Antenna resonating element  54  may include one or more arms such as arm  58 . Return path  62  may couple main resonating element arm  58  to antenna ground  56 . Feed  60  may be coupled in parallel with return path  62  between arm  58  and ground  56 . 
     Metal traces on a flexible printed circuit or other substrate may be used in implementing structures such as resonating element  54 . Antenna ground  56  may be formed using metal traces on a flexible printed circuit or other substrate, using portions of housing  12  or other housing structures, using portions of internal device components, and using other conductive structures in device  10 . As an example, antenna ground  56  may be formed from a metal can or other structure that forms a cavity for antenna  32 . The can may be hollow and filled with a dielectric such as air and/or plastic. The metal can may have walls that define a cavity with an opening that faces the exterior of housing  12 . Antenna resonating element  54  may be formed from patterned metal traces on a flexible printed circuit that is mounted in the metal can over the opening. The walls of the metal can may help to isolate the antenna from internal components in device  10 , so that antenna performance is not sensitive to the presence and position of internal device components. 
     Housing  12  may be formed from plastic or other dielectric that is transparent to radio-frequency signals. If desired, housing  12  may be formed from conductive materials such as metal. In this type of configuration, a plastic insert or other structure formed from dielectric may be mounted within an opening in the metal housing to form an antenna window (i.e., a window in the housing that is transparent to radio-frequency antenna signals). 
       FIG. 8  is a perspective view of a portion of an illustrative housing  12  for electronic device  10 . In the example of  FIG. 8 , device  10  has a cylindrical shape such as the cylindrical shape of device  10  of  FIG. 5 . As shown in  FIG. 8 , housing  12  has a curved sidewall portion such as housing sidewall  12 - 1  and a planar top portion such as planar upper housing wall  12 - 2 . Housing structures  12 - 1  and  12 - 2  may be formed from metal or other conductive material (as an example). Antenna window  64  may be formed from a dielectric material such as plastic. As shown in  FIG. 8 , antenna window  64  may have a curved shape that matches the curved shape of curved housing wall  12 - 1 . Antenna  32  may be mounted behind window  64 . To accommodate the curved surface shape of window  64 , antenna  32  may have a mating curved surface. The curved surface of antenna  32  may be formed by bending an antenna substrate such as a flexible printed circuit containing antenna traces. The flexible printed circuit may, for example, be bowed outward so that the flexible printed circuit has a curved surface that matches the curved inner surface of antenna window  64 . Cavity structures such as a metal can may have corresponding curved portions. 
       FIG. 9  is an exploded perspective view of antenna  32  in a configuration in which antenna  32  has been configured to mate with a curved structure such as a curved dielectric housing or a curved dielectric window member in a housing. As shown in  FIG. 9 , antenna  32  may include antenna resonating element  54  and antenna ground  56 . Antenna resonating element  54  may be formed from patterned metal traces  68  on flexible printed circuit  70 . Flexible printed circuit  70  may contain one or more layers of metal traces and one or more layers of flexible dielectric material. Vias may couple together metal traces in different layers of flexible printed circuit  70 . With one illustrative arrangement, flexible printed circuit  70  may be formed from a sheet of flexible polymer such as a layer of polyimide and metal traces  68  may be formed from metals such as copper, aluminum, gold, metal alloys, or other metals. 
     Openings such as hole  84  may be formed in flexible printed circuit  70 . There may be, for example, a hole at each of the four corners of flexible printed circuit  70  (e.g., in a configuration of the type shown in  FIG. 9  in which flexible printed circuit  70  has a rectangular outline). Flexible printed circuit  70  may be bent around bend axis  86  (i.e., flexible printed circuit  70  may be bowed outwards to form a convex shape). With this type of arrangement, the exposed upper surface of flexible printed circuit  70  has a curved shape that mates with a curved inner surface of antenna window  64  ( FIG. 8 ). 
     Antenna ground  56  may be formed from metal can  72 . Can  72  may be a stamped sheet metal structure or may be formed using other techniques (e.g., welding, soldering, machining, stamping, die-cutting, molding, etc.). As shown in  FIG. 9 , can  72  may have sidewalls  74  and lip  76 . Sidewalls  74  may form a cavity with an opening such as cavity  88 . Lip  76  may surround the opening of cavity  88  and may be formed from portions of sidewalls  74  that are bent outwards from the opening (e.g., portions oriented at a right angle with respect to sidewalls  74 ). Lip  76  may have a flat upper surface that mates with ground traces  80  that lie along the periphery of rectangular flexible printed circuit  70 . Ground traces  80  may have the shape of a rectangular ring (e.g., in configurations in which flexible printed circuit  70  has a rectangular outline). 
     Conductive material  78  (e.g., solder, conductive adhesive, metal in a welded structure, etc.) may be used to electrically and mechanically couple lip  76  of antenna can  72  to ring-shaped ground traces  80  on flexible printed circuit  70 . Ground traces  80  may surround the periphery of flexible printed circuit  70  (i.e., ground traces  80  may run along the peripheral edge of flexible printed circuit  70 ) and may therefore sometimes be referred to as peripheral ground traces. Ground traces  80  may be formed on the lower surface of printed circuit  70  (and, if desired, other layers of flexible printed circuit  70 ) to short antenna ground traces  80  to lip  76  and other portions of can  72  in antenna ground  56 . Lip  76  may have openings such as opening  82  that mate with respective openings  84  in flexible printed circuit  70 . Screws may pass through openings  82  and  84  (e.g., to screw antenna  32  to an antenna window and/or metal housing  12 ). 
     Lip  76  may have a curved shape that mates with the curved shape of bent flexible printed circuit  70 . This allows can  72  and flexible printed circuit  70  to be mounted flush with the curved interior surface of antenna window  64  or other curved structures in device  10 . If desired, lip  76  and flexible printed circuit  70  may have other shapes (e.g., undulating shapes with multiple bends, planar shapes with no bends, convex shapes, concave shapes, etc.). 
       FIG. 10  is a cross-sectional view of antenna  32  in electronic device  10  taken along line  90  of  FIG. 8  and viewed in direction  92 . As shown in  FIG. 10 , antenna window  64  may have a curved shape with a curved outer surface  94  that matches curved outer surface  96  of housing  12 . Housing  12  and antenna window  64  may, if desired, have opposing curved inner surfaces that run parallel to their outer surfaces. 
     Antenna resonating element  54  may be formed from patterned antenna traces  68  on flexible printed circuit  70 . Metal can  72  may form a cavity such as cavity  88 . Can  72  and cavity  88  may have an opening such as opening  100  that faces outwards in direction  102  towards antenna window  64 . 
     Antenna can  72  may be coupled to ground using conductive material  98  (e.g., conductive adhesive, solder, a conductive gasket, or other conductive material). As shown in  FIG. 10 , peripheral ground traces  80  on flexible printed circuit  70  may include lower ground traces  80 - 1  on the lower surface of flexible printed circuit  70 , upper ground traces  80 - 2  on the upper surface of flexible printed circuit  70 , and vias  80 - 3  that short traces  80 - 1  and  80 - 2  together. Conductive material  78  such as solder or conductive adhesive may be used to short traces  80 - 1  to the exposed upper surface of lip  76  while attaching flexible printed circuit  70  in a bent configuration over opening  100 . Conductive material  98  may couple ground traces  80  (e.g., upper ground trace  80 - 2 ) to the exposed inner surface of metal housing  12 . Using this type of arrangement, can  72  may be sealed to housing  12 , thereby isolating the antenna resonating element in antenna  32  from internal components in housing  12 . 
     A connector such as a cable connector may be mounted to flexible printed circuit  70 . As shown in  FIG. 11 , for example, cable connector  104  may be mounted to tab portion  106  of flexible printed circuit  70  along the edge of flexible printed circuit  70 . Cable connector  104  may be a U.FL connector, an MHF connector, another miniature coaxial cable connector, or other connector. Conductive traces  112  on printed circuit  70  may form a transmission line that is used for coupling the positive and ground terminals of connector  104  to antenna terminals  36  and  38 . 
     Flexible printed circuit  70  may be mounted to lip  76  of can  72  so that flexible printed circuit connector tab  106  and connector  104  are aligned with notch  76 N in lip  76 . Notch  76 N may be formed from a rectangular opening or other gap in lip portion  76  of can  72  to accommodate bending of tab  106  downwards in direction  108 . The underside of tab  106  may be provided with a rectangular metal trace that forms a ground pad. The ground pad may be soldered to portion  110  of wall  74  in can  72  after tab  106  has been bent downwards in direction  108 . Tab  106  may have a rectangular shape, a semicircular shape, a triangular shape, or other suitable shape. 
     As shown in  FIG. 12 , tab  106  may have a right angle bend so that the plane of tab  106  lies perpendicular to the plane of flexible printed circuit  70 . Solder  126  may couple tab  106  to metal can wall  74  (i.e., a metal solder pad on the underside of tab  106  may be soldered to wall  74  using solder  126 ). The configuration of  FIG. 12  in which tab  106  is bent at a right angle to pass through notch  76 N and lie on wall  74  of can  72  allows wall  74  to serve as a stiffener that supports flexible printed circuit tab  106  and cable connector  104 . Tab  106  forms an integral portion of flexible printed circuit  70  and the antenna traces on flexible printed circuit  70 , thereby avoiding the need to attach separate signal lines to antenna resonating element  54 . 
     A transmission line path such as cable  34  may have a first end such as end  114  and an opposing second end such as end  116 . Connector  118  at end  114  may be coupled to mating connector  120  on printed circuit board  122 . Components  124  such as radio-frequency transceiver circuitry  44  and other integrated circuits and devices may be mounted on printed circuit board  122 . Printed circuit board  122  may be a flexible printed circuit, a rigid printed circuit board, or other substrate for mounting electrical components. At end  116 , cable  34  may have a connector such as connector  128 . Connector  128  may mate with connector  104  on flexible printed circuit tab  106 , thereby coupling radio-frequency transceiver circuitry  44  to antenna  32 . 
     Transmission line structures such as transmission line  34  and transmission line  112  may be implemented using printed circuit transmission line structures, coaxial cable transmission line structures, or other types of transmission line structures.  FIG. 13  is a cross-sectional side view of a microstrip transmission line structure of the type that may be used in forming some or all of transmission line path  34  of  FIG. 6  and/or path  112  of  FIG. 6 . As shown in  FIG. 13 , path  200  (e.g., some or all of path  34  and/or path  112 ) may include dielectric substrate  130  (e.g., a printed circuit substrate such as a flexible printed circuit substrate), positive signal trace  40  and ground plane signal trace  42 . 
       FIG. 14  is a cross-sectional side view of a stripline transmission line. Transmission line  200  of  FIG. 14  (e.g., some or all of path  34  and/or path  112 ) may have a dielectric substrate  130 , positive signal line trace  40 , and ground traces  42 . Ground traces  42  may run above and below positive signal line  40 . 
     As shown in the top view of antenna structures  32  of  FIG. 15 , flexible printed circuit  70  may be provided with multiple tabs  132  around the periphery of metal can  72 . Notches in lip  76 , an inwardly-protruding lip shape, or other structures in antenna  32  can be used to allow tabs  132  to be bent downwards against the sides of metal can  72 . Solder, conductive adhesive, or other attachment mechanisms may be used to electrically short and mechanically attach tabs  132  of flexible printed circuit  70  to the sides of can  72 . 
       FIG. 16  is a top view of antenna structures  32  in a configuration in which flexible printed circuit  70  has been provided with a protruding portion (e.g., a tab) such as tail  140 . Tail  140  may be formed as an integral portion of flexible printed circuit  70 . Coaxial cable  34  or other transmission line structures may be coupled to terminals  36  and  38  of antenna  32 . Conductive material  142  (e.g., solder and/or conductive adhesive or other materials) may be used to attach cable  34  to tail  140 . A solder pad structure may be formed on the upper surface of tail  140  to accept solder  142 . An opposing solder pad on the lower surface of tail  140  may be used to facilitate soldering of tail  140  to can  72  and/or lip  74 . Ground pads on the opposing upper and lower surfaces of tail  142  may be shorted to each other using vias. Vias may also be used when connecting different ground planes such as ground planes  42  of  FIG. 14  or other flexible printed circuit structures. The presence of tail  140  may help relieve strain and thereby prevent cable  34  from becoming detached from traces  68  in flexible printed circuit  70 . Solder may be used to couple a center conductor in cable  34  to terminal  36  and may be used to couple an outer conductor in cable  34  to terminal  38 . 
     If desired, tunable components, filter components, matching network components, and other circuit components may be mounted on flexible printed circuit  70 , as illustrated by component  144  of  FIG. 16 . Components such as component  144  may include adjustable capacitors, adjustable inductors, adjustable resistors, fixed capacitors, inductors, and resistors, switching circuitry, and other tunable circuits. Components such as component  144  may be packaged in surface mount technology packages or other packages that are soldered to metal traces on flexible printed circuit  70 . There may be multiple components that are soldered to metal traces  68  on flexible printed circuit  70 . The configuration of  FIG. 16  in which a single component has been soldered to traces  68  is merely illustrative. 
     The flexible printed circuit on which antenna resonating element structures for antenna resonating element  54  are formed may be shared with other circuitry such as radio-frequency transceiver circuitry, switching circuitry, filter circuitry, sensor circuitry, impedance matching circuitry, and circuitry not directly associated with wireless operations (e.g., microphones, sensors, filters, etc.). 
     The use of flexible printed circuits in forming antenna structures  32  allows the antenna resonating element and ground plane structures to be flexed to accommodate a curved structure such as a curved antenna window. For slightly curved or planar windows, a thin rigid printed circuit board such as a fiberglass-filled epoxy board (e.g., an FR4 board) or other substrate may also be used. 
     If desired, portions of a printed circuit antenna structure such as tail  140  of  FIG. 16  may be implemented using a printed circuit that has both a rigid portion (e.g., for the non-tail area) and a flexible portion (e.g., for tail  140 ). Printed circuits in which one or more flexible portions extend from a rigid portion are sometimes referred to as rigid flex boards, rigid flex substrates, or rigid flex. If desired, flexible printed circuit antennas  32  may be implemented using rigid flex substrates in which the flexible portion of the rigid flex substrate is bent as described in connection with flexible printed circuit  70  (i.e., flexible printed circuit  70  may be implemented using rigid flex). Printed circuit substrates (flexible printed circuits, rigid flex substrates, etc.) may, if desired, be provided with stiffeners (e.g., a polyimide sheet, a stainless steel sheet, or other stiffening structures). Such stiffening structures may enhance mechanical support during soldering and assembly. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20130605
Publication Date: 20160920
Grant Date: 20160920
Priority Date: 20130605
Inventors: IRCI ERDINC
GUTERMAN JERZY
CHEN CHUN-LUNG
PASCOLINI MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 52005012