PATENT DOCUMENT

Publication Number: US-9397387-B1
Application Number: US-201514733839-A
Country: US
Kind Code: B1

Title: Electronic device with isolated cavity antennas

Abstract:
An electronic device may have a metal housing. The metal housing may have an upper housing in which a component such as a display is mounted and a lower housing in which a component such as a keyboard is mounted. Hinges may be used to mount the upper housing to the lower housing for rotation about a rotational axis. A slot-shaped opening may separate the upper and lower housing. A flexible printed circuit with ground traces may bisect the slot-shaped opening to form first and second slots. Cavity antennas may be aligned with the slots. Each cavity antenna may include a hollow carrier with a pair of speakers. The speakers may have ports that emit sound through aligned openings in the lower housing. Conductive gaskets surrounding the ports may acoustically seal the speaker ports while shorting the cavity antenna to the lower housing.

Claims:
What is claimed is: 
     
       1. A portable computer, comprising:
 a housing having an upper metal housing that contains a display and having a lower metal housing that contains a keyboard; 
 hinges that connect the upper metal housing to the lower metal housing, wherein the upper metal housing rotates relative to the lower metal housing about a rotational axis between a closed position and an open position; and 
 an antenna mounted entirely between opposing upper and lower portions of the lower metal housing and between the hinges, wherein the upper metal housing has a rear metal portion that is separated from the lower metal housing by a first slot when the upper metal housing is in the closed position and that is separated from the lower metal housing by second and third slots when the upper metal housing is in the open position and wherein the antenna transmits and receives antenna signals through the first, second, and third slots. 
 
     
     
       2. The portable computer defined in  claim 1  wherein the first slot, the second slot, and the third slot run parallel to the rotational axis. 
     
     
       3. The portable computer defined in  claim 2  wherein the antenna transmits and receives the antenna signals through the first slot when the upper metal housing is in the closed position. 
     
     
       4. The portable computer defined in  claim 3  wherein the antenna transmits and receives the antenna signals through the second and third slots when the upper metal housing is in the open position. 
     
     
       5. The portable computer defined in  claim 4  wherein the antenna comprises a cavity antenna. 
     
     
       6. The portable computer defined in  claim 5  wherein the cavity antenna is one of a pair of first and second cavity antennas located between the hinges. 
     
     
       7. The portable computer defined in  claim 6  further comprising a signal path that passes between the upper metal housing and the lower metal housing between the first and second cavity antennas. 
     
     
       8. The portable computer defined in  claim 7  wherein the first and second cavity antennas comprise dual band antennas. 
     
     
       9. The portable computer defined in  claim 8  wherein the first and second cavity antennas are configured to operate in a 2.4 GHz communications band and a 5 GHz communications band. 
     
     
       10. The portable computer defined in  claim 4  wherein the antenna is one of a pair of first and second antennas located between the hinges and wherein the portable computer comprises a signal path that passes between the upper metal housing and the lower metal housing between the first and second cavity antennas. 
     
     
       11. A portable computer, comprising:
 a display; 
 an upper metal housing in which the display is mounted; 
 a keyboard; 
 a lower metal housing in which the keyboard is mounted; 
 hinges that connect the upper metal housing to the lower metal housing, wherein the upper metal housing rotates relative to the lower metal housing about a rotational axis between a closed position and an open position; and 
 first and second antenna resonating elements mounted in the lower metal housing between the hinges and entirely between opposing upper and lower portions of the lower metal housing, wherein the upper metal housing has a rear metal portion that is separated from the lower metal housing by a slot when the upper metal housing is in the closed position. 
 
     
     
       12. The portable computer defined in  claim 11  wherein the first antenna resonating element is a resonating element for a first cavity antenna and the second antenna resonating element is a resonating element for a second cavity antenna. 
     
     
       13. The portable computer defined in  claim 12  wherein the slot that separates the rear metal portion from the lower metal housing when the upper metal housing is in the closed position is a first slot and the rear metal portion is separated from the lower metal housing by a second slot when the upper metal housing is in the open position. 
     
     
       14. The portable computer defined in  claim 13  wherein the first and second cavity antennas transmit and receive antenna signals through the first slot when the upper metal housing is in the closed position. 
     
     
       15. The portable computer defined in  claim 14  wherein the first and second cavity antennas transmit and receive antenna signals through the second slot when the upper metal housing is in the open position. 
     
     
       16. The portable computer defined in  claim 15  further comprising a third slot that separates the rear metal portion from the lower metal housing when the upper housing is in the open position. 
     
     
       17. The portable computer defined in  claim 16  wherein the first and second cavity antennas transmit and receive antenna signals through the second and third slots when the upper housing is in the open position. 
     
     
       18. The portable computer defined in  claim 17  wherein the first and second cavity antennas transmit and receive the antenna signals in communications bands at 2.4 GHz and 5 GHz. 
     
     
       19. A portable computer, comprising:
 a display; 
 an upper metal housing in which the display is mounted; 
 a keyboard; 
 a lower metal housing in which the keyboard is mounted; 
 hinges that connect the upper metal housing to the lower metal housing, wherein the upper metal housing rotates relative to the lower metal housing about a rotational axis between a closed position and an open position; and 
 first and second cavity antennas mounted in the lower metal housing between the hinges and entirely between opposing upper and lower portions of the lower metal housing, wherein the upper metal housing has a rear metal portion that is separated from the lower metal housing by a gap that extends along the rotational axis between the hinges when the upper metal housing is in the closed position and wherein the first and second cavity antennas transmit and receive antenna signals through the gap when the upper metal housing is in the closed position. 
 
     
     
       20. The portable computer defined in  claim 19  wherein the first and second antennas are configured to operate in communications bands at 2.4 GHz and 5 GHz.

Description:
This application is a continuation of patent application Ser. No. 14/640,787, filed Mar. 6, 2015, which is hereby incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     This relates generally to electronic devices and, more particularly, to wireless electronic devices with antennas. 
     Electronic devices often include antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, the presence of conductive housing structures can influence antenna performance. Antenna performance may not be satisfactory if the housing structures are not configured properly and interfere with antenna operation. Device size can also affect performance. It can be difficult to achieve desired performance levels in a compact device, particularly when the compact device has conductive housing structures. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices. 
     SUMMARY 
     An electronic device may have a metal housing. The metal housing may have an upper housing portion such as a lid in which a component such as a display is mounted. The metal housing may have a lower housing portion such as a base housing containing a component such as a keyboard. Hinges may be used to mount the upper housing portion to the lower housing portion. The upper housing portion may be rotated relative to the lower housing portion using the hinges. 
     A slot-shaped opening may separate the upper and lower housing portions. The slot-shaped opening may be present both when the lid is open and when the lid is closed. A flexible printed circuit with ground traces may bisect the slot-shaped opening to form first and second slots. A first of the hinges and a first ground trace on the flexible printed circuit may form opposing ends of the first slot. A second of the hinges and a second ground trace on the flexible printed circuit may form opposing ends of the second slot. Signal traces on the flexible printed circuit may be interposed between the first and second ground traces. 
     Cavity antennas may be aligned with the slots, which serve as apertures for the antennas. Each cavity antenna may include a hollow carrier with a pair of speakers. The speakers may have ports that emit sound through aligned openings in the lower housing. Conductive gaskets surrounding the ports may acoustically seal the speaker ports while shorting the cavity antennas to the lower housing. 
     An angle sensor may be used to measure the angle between the upper housing portion and the lower housing portion. Control circuitry may tune the antennas using tunable circuitry. The control circuitry may tune the antennas based on measurements made using a lid angle sensor or other circuitry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device such as a laptop computer in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless circuitry in accordance with an embodiment. 
         FIG. 3  is a perspective view of an illustrative antenna and associated transceiver circuitry that may be used in an electronic device of the type shown in  FIG. 1  in accordance with an embodiment. 
         FIG. 4  is a graph in which antenna performance (standing wave ratio SWR) has been plotted as a function of operating frequency for an illustrative antenna of the type shown in  FIG. 3  in accordance with an embodiment. 
         FIG. 5  is a perspective view of an illustrative antenna with a cavity that has been formed from metal traces on a dielectric carrier that also serves as a speaker box in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative cavity antenna such as the cavity antenna of  FIG. 5  showing how the interior of the dielectric carrier may serve as speaker volumes for a pair of speakers in accordance with an embodiment. 
         FIG. 7  is a perspective view of a rear edge portion of an illustrative laptop computer showing how a slot-shaped opening may be present through which antenna signals may pass when the lid of the laptop computer is closed in accordance with an embodiment. 
         FIG. 8  is a top view of an illustrative interior portion of a laptop computer showing how antennas may be located on either side of the computer housing and may operate through slot apertures that are isolated from each other by ground traces on the edges of flexible printed circuit structures in accordance with an embodiment. 
         FIG. 9  is a side view of an illustrative stack of conductive gasket materials that may be used in forming a conductive gasket in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative laptop computer showing how an antenna may be grounded using a conductive speaker gasket and may operate through a slot aperture between a lid and base housing for the laptop computer when the lid is in a closed position in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of an illustrative laptop computer showing how an antenna may be grounded using a conductive speaker gasket and may operate through a pair of slot apertures between a lid and base housing for the laptop computer when the lid is in an open position in accordance with an embodiment. 
         FIG. 12  is a graph in which antenna performance (standing-wave ratio SWR) has been plotted as a function of frequency to show how antenna bandwidth may be enlarged to accommodate potential detuning during operation in accordance with an embodiment. 
         FIG. 13  is a graph in which antenna efficiency has been plotted as a function of lid angle for different antenna configurations in accordance with an embodiment. 
         FIG. 14  is a schematic diagram showing how an antenna may have a tuning circuit that is adjusted based on lid angle in accordance with an embodiment. 
         FIG. 15  is a diagram of an illustrative tunable cavity antenna that may be tuned based on sensed lid angle in accordance with an embodiment. 
         FIG. 16  is a graph in which antenna performance (standing-wave ratio SWR) has been plotted as a function of frequency under different operating conditions and tuning settings in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may contain wireless circuitry. For example, electronic device  10  may contain wireless communications circuitry that operates in long-range communications bands such as cellular telephone bands and wireless circuitry that operates in short-range communications bands such as the 2.4 GHz Bluetooth® band and the 2.4 GHz and 5 GHz WiFi® wireless local area network bands (sometimes referred to as IEEE 802.11 bands or wireless local area network communications bands). Device  10  may also contain wireless communications circuitry for implementing near-field communications, communications at 60 GHz, light-based wireless communications, satellite navigation system communications, or other wireless communications. 
     Device  10  may be a handheld electronic device such as a cellular telephone, media player, gaming device, or other device, may be a laptop computer, tablet computer, or other portable computer, may be a desktop computer, may be a computer display, may be a display containing an embedded computer, may be a television or set top box, or may be other electronic equipment. Configurations in which device  10  has a rotatable lid as in a portable computer are sometimes described herein as an example. This is, however, merely illustrative. Device  10  may be any suitable electronic equipment. 
     As shown in the example of  FIG. 1 , device  10  may have a housing such as housing  12 . Housing  12  may be formed from plastic, metal (e.g., aluminum), fiber composites such as carbon fiber, glass, ceramic, other materials, and combinations of these materials. Housing  12  or parts of housing  12  may be formed using a unibody construction in which housing structures are formed from an integrated piece of material. Multipart housing constructions may also be used in which housing  12  or parts of housing  12  are formed from frame structures, housing walls, and other components that are attached to each other using fasteners, adhesive, and other attachment mechanisms. 
     Some of the structures in housing  12  may be conductive. For example, metal parts of housing  12  such as metal housing walls may be conductive. Other parts of housing  12  may be formed from dielectric material such as plastic, glass, ceramic, non-conducting composites, etc. To ensure that antenna structures in device  10  function properly, care should be taken when placing the antenna structures relative to the conductive portions of housing  12 . If desired, portions of housing  12  may form part of the antenna structures for device  10 . For example, conductive housing sidewalls may form all or part of an antenna ground. The antenna ground include one or more cavities for cavity-backed antennas. The cavities in the cavity-backed antennas may be formed from metal traces on dielectric carriers and may be electrically shorted to portions of housing  12  near a slot-shaped opening between the upper and lower portions of the housing. 
     As shown in  FIG. 1 , device  10  may have input-output devices such as track pad  18  and keyboard  16 . Device  10  may also have components such as a camera, microphones, speakers, buttons, removable storage drives, status indicator lights, buzzers, sensors, and other input-output devices. These devices may be used to gather input for device  10  and may be used to supply a user of device  10  with output. Ports in device  10  may receive mating connectors (e.g., an audio plug, a connector associated with a data cable such as a Universal Serial Bus cable, a data cable that handles video and audio data such as a cable that connects device  10  to a computer display, television, or other monitor, etc.). 
     Device  10  may include a display such a display  14 . Display  14  may be a liquid crystal display (LCD), a plasma display, an organic light-emitting diode (OLED) display, an electrophoretic display, or a display implemented using other display technologies. A touch sensor may be incorporated into display  14  (i.e., display  14  may be a touch screen display) or display  14  may be insensitive to touch. Touch sensors for display  14  may be resistive touch sensors, capacitive touch sensors, acoustic touch sensors, light-based touch sensors, force sensors, or touch sensors implemented using other touch technologies. 
     Device  10  may have a one-piece housing or a multi-piece housing. As shown in  FIG. 1 , for example, electronic device  10  may be a device such as a portable computer or other device that has a two-part housing formed from an upper housing portion such as upper housing  12 A and lower housing portion such as lower housing  12 B. Upper housing  12 A may include display  14  and may sometimes be referred to as a display housing or lid. Lower housing  12 B may sometimes be referred to as a base housing or main housing. 
     Housings  12 A and  12 B may be connected to each other using hinge structures located in region  20  along the upper edge of lower housing  12 B and the lower edge of upper housing  12 A). For example, housings  12 A and  12 B may be coupled by hinges  26 . Hinges  26  may be located at opposing left and right edges of housing  12  along hinge axis  22 . A slot-shaped opening such as opening (slot)  30  may be formed between upper housing  12 A and lower housing  12 B and may be bordered on either end by hinges  26 . Hinges  26 , which may be formed from conductive structures such as metal structures, may allow upper housing  12 A to rotate about axis  22  in directions  24  relative to lower housing  12 B. The plane of lid (upper housing)  12 A and the plane of lower housing  12 B may be separated by an angle that varies between 0° when the lid is closed to 90°, 140°, or more when the lid is fully opened. 
     Metal traces on one or more flexible printed circuits  31  may bisect slot  30  and thereby create two slots  30 - 1  and  30 - 2 . Slots  30 - 1  and  30 - 2  may be surrounded by metal. For example, slots  30 - 1  and  30 - 2  may be surrounded by metal portions of housing  12 A and  12 B on their top and bottom edges and hinges  26  and flexible printed circuit traces on flexible printed circuit(s)  31  on their opposing ends). Slots  30 - 1  and  30 - 2  may serve as antenna apertures for respective antennas  40  in device  10 . These antennas may be used to form a multiple-input-multiple-output (MIMO) antenna array. 
     Speakers in device  10  may be located within housing  12 . Housing  12  may have perforations such as circular holes or may have other speaker openings to allow sound to exit the interior of device  10 . Arrays of speaker openings (e.g., circular holes or other housing openings) may be formed on the left and right edges of housing  12 B (e.g., in positions flanking the right and left sides of keyboard  16 ), may be formed along the upper edge of housing  12 B adjacent to hinge region  20 , or may be formed in other suitable locations. Device  10  may have one or more speakers, two or more speakers, three or more speakers, four or more speakers, or other suitable numbers of speakers. In the example of  FIG. 1 , speaker openings  28  have been formed in four groups (clusters) each of which overlaps a respective speaker in a group of four speakers that have been mounted within the interior of device  10 . If desired, dummy openings (i.e., housing openings that do not overlap any speakers) may be formed within housing  12  between respective groups of speaker holes  28 , so that housing  12 B appears to have a single uninterrupted band of speaker perforations running along the upper edge of housing  12 B near hinge axis  22 . The configuration of  FIG. 1  in which speaker openings  28  are formed in four different speaker locations is merely illustrative. 
     A schematic diagram showing illustrative components that may be used in device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  30 . Storage and processing circuitry  30  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  30  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  30  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  30  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  30  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  44  may include input-output devices 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 in circuitry  44  may include user interface devices, data port devices, and other input-output components. For example, input-output devices in circuitry  44  may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, cameras, buttons, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, audio circuitry  32  such as microphones and speakers, and other 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, 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 for handling voice data and non-voice data in various radio-frequency communications bands. For example, circuitry  34  may include wireless local area network transceiver circuitry to handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and to handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may include cellular telephone transceiver circuitry 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). 
     Wireless communications circuitry  34  may 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 satellite navigation system circuitry such as global positioning system (GPS) receiver circuitry 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 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. 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. 
     If desired, antennas  40  may include one or more inverted-F antennas with parasitic resonating elements. This type of illustrative antenna configuration is shown in  FIG. 3 . As shown in  FIG. 3 , antenna  40  may include antenna resonating element  50  and antenna ground  52 . Antenna resonating element  50  may have one or more branches such as branches  50 - 1  and  50 - 2 . Branch  50 - 1  may handle lower frequencies (e.g., 2.4 GHz) and branch  50 - 2  may handle higher frequencies (e.g., 5 GHz) or branches  50 - 1  and  50 - 2  may resonate in other suitable communications bands. Parasitic antenna resonating element  58  may be an L-shaped metal element that is terminated at ground  52 . The presence of element  58  may help broaden the bandwidth of antenna  40  (e.g., in high frequency band such as a 5 GHz band). 
     Antenna  40  may have a return path such as short circuit path  54  that is coupled between antenna resonating element  50  and ground  52 . Antenna feed  56  may have positive antenna feed terminal  98  and ground antenna feed terminal  100  and may be coupled between resonating element  50  and ground  52  in parallel with return path  54 . 
     Transmission line paths such as transmission line  92  may be used to couple antenna structures  40  to transceiver circuitry such as transceiver circuitry  90 . Transmission line  92  may have a positive transmission line path such as path  94  that is coupled to positive antenna feed terminal  98  and a ground transmission line path such as path  96  that is coupled to ground antenna feed terminal  100 . Transceiver circuitry  90  may operate at wireless local area network bands such as the 2.4 GHz and 5 GHz bands or other suitable short-range or long-range communications bands. Transmission lines in device  10  such as transmission line  92  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 the transmission lines, if desired. As an example, a circuit component such as capacitor  102  or other circuitry may be interposed in positive transmission line path  94  or elsewhere within transmission line  92  between transceiver circuitry  90  and antenna  40 . Capacitor  102  may help broaden the bandwidth of antenna  40  so that antenna performance is satisfactory over a range of operating conditions for device  10  (e.g., operations at various lid angles for lid  12 A relative to base  12 B). 
       FIG. 4  is a graph in which antenna performance (i.e., standing wave ratio SWR) has been plotted as a function of operating frequency f for antenna  40  of  FIG. 3 . Curve  60  shows how antenna  40  may operate in a low frequency band such as a 2.4 GHz band (e.g., to support WiFi® or Bluetooth® signals). Low band performance (curve  60 ) may be supported using low band arm  50 - 1  of antenna resonating element  50 . Curve  62  may correspond to the coverage of antenna  40  that is supported by high band arm  50 - 2  of antenna  40  (e.g., the response of antenna resonating element  50  at 5 GHz). Curve  64  shows how a slightly shifted high band resonance may be supported using parasitic antenna resonating element  58 . Element  50  may be directly feed at antenna feed  56  using transmission line  92 . Parasitic element  58  is not directly fed, but rather is coupled to antenna resonating element  50  through electromagnetic near-field coupling. The overall response of antenna  40  in its high band at 5 GHz, which is represented by curve  66 , is characterized by both a contribution from antenna resonating element  50  (curve  62 ) and a contribution from parasitic antenna resonating element  58  (curve  64 ). The presence of element  58  helps broaden the high band response of antenna  40  to ensure that the high band is covered satisfactorily. 
     Antenna  40  may be formed from metal traces on a dielectric support structure. The dielectric support structure may be formed from ceramic, plastic, foam, glass, other dielectric materials, or combinations of these materials. Illustrative configurations in which the dielectric support structure is plastic support structure may sometimes be described herein as an example.  FIG. 5  is a perspective view of an illustrative antenna formed from patterned metal traces on a plastic support (sometimes referred to as an antenna carrier). In the example of  FIG. 5 , support structure  76  forms an antenna carrier for metal antenna traces. The metal traces may be patterned using laser patterning techniques such as techniques in which selected portions of a plastic surface are activated and become coated with metal during subsequent electroplating operations. If desired, other techniques for forming antenna  40  may be used (e.g., techniques such as machining, attachment of patterned metal foil, mounting of patterned flexible printed circuits, etc.). 
     In the example of  FIG. 5 , the metal antenna traces on plastic support structure  76  include traces that form antenna ground  52 , antenna resonating element  50 , and parasitic antenna resonating element  58 . Support structure  76  may be a hollow box-shaped structure or other structure having exterior surfaces surrounding a hollow interior. Structure  76  may be, for example, a six sided box. Metal traces may be patterned on structure  76  so that ground  52  forms a grounded antenna cavity. For example, ground traces  52  may be formed on five of the six sides of the box. The front face of support  76  (in the orientation of  FIG. 5 ) may be free of ground traces and may be used to support metal traces that form antenna resonating element  50  and parasitic element  58 , as shown in  FIG. 5 . In this type of configuration, metal traces  52  form an antenna cavity and antenna  40  is a cavity-backed antenna (i.e., antenna  40  is a cavity antenna). Transmission line  92  may be formed from a coaxial cable that is coupled to antenna  40  at feed  56  (terminals  98  and  100 ). 
     In addition to serving as an antenna carrier for antenna  40 , support structure  76  may serve as a speaker enclosure (sometimes referred to as a speaker box). As shown in  FIG. 5 , support structure  76  may serve as a speaker enclosure for a pair of speakers  70 . Speakers  70  may be formed from speaker drivers located at opposing ends of structure  76 . The interior of structure  76  may be divided into separate volumes for the speakers. Each of speakers  70  may emit sound through a respective one of ports  72 . Ports  72  may be covered with a layer of open cell foam, a metal or plastic mesh, or other structures for preventing dust intrusion into the interior of structure  76  or, if desired, ports  72  may have one or more open areas (i.e., areas not covered with mesh) that allow sound to exit speakers  70 . 
     To create a satisfactory acoustic and electrical seal with housing  12 , each speaker port  72  may be surrounded by a gasket such as gasket  74 . Gaskets  74  may be ring shaped conductive compressible structures. If, for example, speaker ports  72  have rectangular shapes, gaskets  74  may have the shapes of rectangular rings. Gaskets  74  may be formed from one or more layers of conductive foam, conductive fabric, layers that include conductive vias and other conductive structures, conductive adhesive, and other conductive structures that allow gaskets  74  to form acoustic seals around speaker ports  72  while electrically shorting antenna traces such as ground trace  52  to housing  12 . The seal formed around speaker ports  72  by gaskets  74  helps prevent dust and sound from entering into the interior of housing  12 . Gaskets  74  also help ground antenna ground traces  52  on support structure  76  to metal housing  12 , which may serve as a portion of the ground for antenna  40 . The presence of conductive gaskets  74  may also help prevent radio-frequency antenna signals that are emitted by antenna  40  from being coupled into the interior of housing  12  as signal noise. 
       FIG. 6  is a cross-sectional side view of antenna  40  of  FIG. 5  taken along line  80  and viewed in direction  82 . As shown in  FIG. 6 , the interior of hollow support structure  76  may be separated into individual cavities  130 - 1  and  130 - 2  by a divider structure such as interior wall  761 . Cavities  130 - 1  and  130 - 2  may serve as speaker volumes for respective speakers  70 . Each speaker  70  may have a respective speaker driver  128 . Speaker drivers  128  may have coils  126 , magnets, and other electromagnetic structures that can move diaphragms  84  in response to signals receive over acoustic signal lines  122 . This produces sound that is emitted through mesh  78  or other acoustically transparent speaker port material in speaker ports  72 . Conductive gaskets  74  may run around the peripheral edges of speaker ports  72  on the upper surface of support  76  (e.g., gaskets  74  may be shorted to metal  52  of  FIG. 5 ). 
     Signal lines  122  may be routed to carrier  76  on a signal path formed from flexible printed circuit  120  or other suitable signal path structure. If desired, circuit elements such as inductors  86  may be interposed in the signal paths coupled to speaker drivers  128 . Inductors  86  may be sized to allow audible frequency signals to pass unimpeded to speaker drivers  84  while blocking high frequency signals such as antenna signals and other radio-frequency signals, thereby reducing unwanted noise in speakers  70 . There are two speakers  70  in structure  76  of  FIG. 6 . More speaker volumes and speakers may be formed in structure  76  or fewer speaker volumes and speakers may be formed in structure  76  if desired. The example of  FIG. 6  in which antenna  40  is formed from a hollow antenna carrier structure that includes two speaker drivers is merely illustrative. 
     If desired, there may be two (or other suitable number) of antennas  40  and four (or other suitable number) of speakers  70  in device  10 . As an example, one antenna  40  and an associated set of two speakers may be located on the left half of housing  12 B and another antenna  40  and its associated set of two speakers may be located on the right half of housing  12 B. Structures  76  may be mounted so that each speaker port  72  is aligned with a corresponding set of speaker openings  28 . 
     Slots  30 - 1  and  30 - 2  may serve as antenna apertures for respective cavity antennas  40  (e.g., antennas that are each formed using a structure such as structure  76  of  FIG. 6 ). Slots  30 - 1  and  30 - 2  may be present in both open-lid and closed-lid configurations for device  10 . An illustrative open-lid configuration in which slots  30 - 1  and  30 - 2  are present is shown in  FIG. 1 . An illustrative rear view of housing  12  showing how a slot such as slot  30 - 2  may be present in a closed-lid configuration for device  10  is shown in  FIG. 7 . As shown in  FIG. 7 , slots  30  such as slot  30 - 2  may have an elongated shapes that extend parallel to axis  22 . During antenna operation, wireless antenna signals that have been transmitted by antennas  40  and wireless antenna signals that are being received by antennas  40  may pass through the antenna apertures formed by slots  30 - 1  and  30 - 2 . 
     As shown in the illustrative interior view of device  10  of  FIG. 8 , antennas  40  may be aligned with the apertures formed by slots  30 - 1  and  30 - 2  (i.e., the right-hand antenna  40  may be aligned with slot  30 - 2  and the left-hand antenna  40  may be aligned with slot  30 - 1 ). Flexible printed circuit(s)  31  may include one or more flexible printed circuits such as a camera flexible printed circuit that carries camera signals, one or two or more than two display flexible printed circuits that carry display data, one or more backlight unit flexible printed circuits that carry power and control signals for a backlight in display  14 , and/or other flexible printed circuits (e.g., a touch sensor flexible printed circuit that carries touch sensor signals for display  14 ). 
     Antennas  40  are preferably isolated from each other (e.g., to optimize MIMO operation). Flexible printed circuit(s)  31  may contain one or more sheets of flexible dielectric substrate material such as a layer of polyimide or a sheet of other flexible polymers (substrate  132 ). Signal lines  136  may be formed in central region  138  of circuit(s)  31 . The left and right edges  140  of flexible printed circuit(s)  31  that border region  138  and lines  136  may contain ground traces  134 . The width of ground traces  134  may be 1-2 mm, more than 1 mm, less than 3 mm, or other suitable thickness. Ground traces  134  may have screw hole openings that receive metal screws  142 . Metal screws  142  may be received within threaded openings in housings  12 A and  12 B, thereby grounding ground traces  134  to the upper and lower portions of housing  12 . The presence of these grounded metal traces in circuit(s)  31  helps divide slot  30  into separate electromagnetically isolated antenna apertures (slots  30 - 1  and  30 - 2 ). This helps ensure that the right and left antennas  40  of device  10  operate independently. 
     Gaskets  74  may be formed from conductive foam, conductive fabric, and/or other conductive structures (i.e., elastomeric structures that can expand outwardly against nearby structures after being compressed). An illustrative cross-sectional side view of conductive foam structures that may be used in forming gaskets  74  is shown in  FIG. 9 . As shown in  FIG. 9 , gasket  74  may be formed from one or more foam layers such as layers  148  that are coupled together in a stack. An opening such as opening  156  (e.g., a rectangular opening formed within a stack of rectangular foam layers) may be used to shape the layers into a structure that serves as gasket  74 . (In the diagram of  FIG. 9 , the material in opening region  156  has not yet been removed.) 
     Foam layers  148  may each include foam substrate layers  146 . The foam of layers  146  may be a closed cell foam that helps ensure that gasket  74  can serve as an acoustically isolating gasket for surrounding speaker port  74 . Closed cell foam does not have openings that pass through the body of the foam, so closed cell foam effectively blocks sound. However, the presence of the cell walls in a closed cell foam can make it challenging to deposit metal or other conductive material into the foam in a way that forms current paths through the foam. Accordingly, foam layers  146  may be provided with metal vias such as vias  150  that pass through the closed cell foam. Metal vias  150  render layers  148  conductive (i.e., layers  146  with vias  150  serve as conductive foam layers in gasket  74 ). Conductive adhesive layers  152  may be used to couple one, two or more, or three or more of layers  148  together and to conductive fabric  154 . The number of layers  148  to be used in gasket  74  may be determined by the desired thickness of gasket  74 . Layers  148  may be 0.5 mm thick, more than 0.5 mm thick, less than 0.5 mm thick, etc. Fabric  154  may be wrapped around some or all of the exterior surfaces of layers  148  to increase the conductivity of gasket  74 . Conductive fabric  154  may be formed from metal fibers, metal coated plastic fibers, fibers treated with metal particles and/or other conductive materials, etc. If desired, layers  148  may be formed from open cell plastic foam plated with metal or other suitable conductive elastomeric structures. The use of closed cell foam with metal vias to form gasket  74  is merely illustrative. 
     A cross-sectional side view of antenna  40  mounted in an illustrative location within housing  12  in alignment with slot  30  (e.g., slot  30 - 1  or slot  30 - 2 ) is shown in  FIG. 10 . As shown in  FIG. 10 , antenna resonating element  50  and the front face of dielectric support structures  76  may face slot  30  in direction  164  so that antenna signals from antenna  40  may pass through slot  30 . Conductive structures such as structures  160  and  162  may be used to ground antenna ground trace  52  of antenna  40  to metal lower housing  12 B. Structure  162  may be a layer of conductive adhesive or other conductive material. Structure  160  may be a conductive foam layer that helps press antenna  40  upwards so that gasket  74  is compressed between ground  52  on the upper surface of carrier  76  and the opposing lower surface of the upper portion of metal lower housing  12 B. The opening in the center of gasket  74  is preferably aligned with speaker openings  28  in housing  12 B and with speaker port  72 . Aligning speaker  70  with the housing speaker ports formed from openings  28  allows sound from speaker port  72  to exit device  10  (e.g., when lid  12 A is open). Gasket  74  forms an acoustic seal around speaker port  72  and prevents sound from leaking into the gap between antenna  40  and housing  12 B. Gasket  74  also forms a conductive path that shorts antenna ground  52  of antenna  40  to the underside of the upper portion of housing  12 B, thereby preventing antenna signals from entering into the interior of housing  12 B via path  166 . This helps ensure that antenna signals being transmitted by antenna  40  will not interfere with circuitry in the interior of device  10  such as display circuitry for display  14 , control circuitry  30 , etc. 
     Upper housing  12 A may have a rear portion such as portion  12 AR that is separated from lower housing  12 B by a sufficient amount when device  10  is in a lid-closed configuration to form gap  30  and thereby allow antenna  40  to transmit and receive wireless signals.  FIG. 11  shows device  10  in an illustrative lid-open configuration in which upper housing (lid)  12 A has been rotated into an open position about hinge axis  22 . In the illustrative configuration of  FIG. 11 , slot  30  has upper and lower portions (in addition to the left and right portions located at different positions along axis  22 ). Antenna signals can pass through either the upper portion of slot  30 , through the lower portion of slot  30 , or through both upper and lower slots  30  of  FIG. 11 . With this type of arrangement, each antenna is associated with a pair of antenna apertures (i.e., the upper slot and lower slot). If desired, each antenna may operate through a single slot in both the open and closed lid position. The illustrative configuration of  FIG. 11  in which the open lid position for device  10  creates a pair of slot apertures for each antenna is merely illustrative. 
     The varying position of housing  12 A with respect to antenna  40  can impose a variable impedance loading onto antenna  40 . As a result, antenna performance can be detuned as the position of housing  12 A is adjusted by a user (e.g., to optimize viewing of display  14  in housing  12 A). This effect is illustrated by the graph of  FIG. 12  in which antenna performance (standing wave ratio SWR) has been plotted as a function of operating frequency fin an illustrative communications band of interest at 2.4 GHz. The curves of  FIG. 12  illustrate the impact of incorporating capacitor  102  into the signal path between transceiver  90  and antenna  40  and illustrate the impact of lid position. Curve  170  illustrates the performance of antenna  40  in a configuration in which lid  12 A is open at an angle of 110° with respect to horizontal and in which capacitor  102  has been omitted. Curve  170 ′ shows how antenna performance for this type of antenna arrangement can be detuned when lid  12 A is closed (i.e., oriented at 0°). Curve  168  corresponds to operation of antenna  40  in a configuration in which capacitor  102  is present and lid  12 A is in an open position at 110°. In the presence of capacitor  102 , the bandwidth of antenna  40  is broadened as illustrated by the broadened shape of antenna resonance curve  168  relative to the shape of curve  170 . The broadening impact of capacitor  102  ensures that antenna  40  will continue to operate satisfactorily at a desired frequency in the 2.4 GHz band even when lid  12 A is closed (curve  170 ′). 
     In the illustrative graph of  FIG. 13 , antenna efficiency has been plotted as a function of lid position (i.e., the position of housing  12 A relative to housing  12 B). Curve  174  corresponds to an antenna arrangement in which capacitor  102  has been omitted. Curve  172 , which exhibits reduced lid position sensitivity, corresponds to an antenna arrangement in which capacitor  102  has been included. 
     As the examples of  FIGS. 12 and 13  illustrate, the use of capacitor  102  helps to reduce the susceptibility of antenna  40  to lid position detuning effects. If desired, other lid-detuning-susceptibility-reduction circuits may be coupled between transceiver  90  and the feed for antenna  40 . The use of capacitor  102  to broaden the response of antenna  40  and thereby reduce the impact of antenna detuning is merely illustrative. 
     Another way in which to reduce the sensitivity of device  10  to lid-position-induced antenna detuning involves monitoring the performance of antenna  40  and/or the position of lid  12 A using monitoring circuitry (e.g., impedance monitoring circuitry, received-signal-strength monitoring circuitry, etc.). Antenna  40  can be provided with tunable circuitry that can retune the antenna and thereby ensure that antenna performance does not vary more than desired. 
     Consider, as an example, the arrangement of  FIG. 14 . As shown in  FIG. 14 , device  10  may have an antenna with tuning circuitry. Tuning circuitry  176  of antenna  40  may include adjustable inductors, adjustable capacitors, and/or other adjustable circuitry. Tuning circuitry  176  may be incorporated into antenna resonating element  50 , a portion of antenna ground  52 , a parasitic element, an antenna feed structure, an impedance matching circuitry, or other wireless circuitry. Control circuitry  30  may provide data to transceiver circuitry  90  when it is desired to transmit this data using antenna  40  and may process wireless data that has been received by transceiver circuitry  90  using antenna  40 . Control circuitry  30  may also receive data from an antenna performance monitoring circuit and/or lid position sensor  178  (e.g., an optically, magnetically, or electrically encoded angle sensor coupled between housings  12 A and  12 B). Based on information on the position of lid  12 A or other information on the state of antenna  40 , control circuitry  30  can adjust tuning circuit  176  to ensure that antenna  40  is performing as desired. 
       FIG. 15  is a diagram showing how tunable circuitry such as tuning circuit  176  can be implanted using a variable capacitor coupled between antenna resonating element  50  and antenna ground  52 . Other types of tuning circuit (e.g., tunable inductors, etc.) can also be used. The tuning configuration of  FIG. 15  is merely illustrative. 
       FIG. 16  is a graph illustrating how tunable circuitry  176  may be adjusted based on information such as measured lid position. Initially, antenna  40  may be operated at desired frequency f 1  with lid  12 A in a first position. Upon moving lid  12 A to a second position, antenna  40  has the potential to become detuned, as indicated by detuned antenna resonance  182  at undesired frequency f 2 . By using an a lid position sensor such as angle sensor  178  or other sensor that is sensitive to the position of lid  12 A relative to housing  12 B, control circuitry  30  can determine that antenna  40  has the potential to be detuned and therefore can adjust tuning circuit  176  by an appropriate amount to compensate. This retunes antenna  40  so that antenna  40  exhibits an antenna resonance such as resonance  184  at desired frequency f 1  (even though lid  12 A has been moved). 
     In general, antenna  40  may be retuned by control circuitry  30  based on data from transceiver  90  (e.g., received signal strength or other suitable metric), based on information form a proximity sensor, touch sensor, accelerometer, compass, or other sensor in device  10 , based on information from a lid angle sensor, etc. The illustrative configuration of  FIG. 14  in which angle sensor  178  is used to provide control circuitry  30  with information for adjusting tunable circuitry  176  is merely illustrative. 
     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: 20150608
Publication Date: 20160719
Grant Date: 20160719
Priority Date: 20150306
Inventors: GUTERMAN JERZY
SWEET EDWARD T.
HUANG HUAN-CHU
BOOTHE DANIEL K.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q13/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/357", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1698", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/20", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/20", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 54609342