PATENT DOCUMENT

Publication Number: US-8952860-B2
Application Number: US-201113038169-A
Country: US
Kind Code: B2

Title: Antenna structures with carriers and shields

Abstract:
Antennas are provided for electronic devices such as portable computers. An electronic device may have a housing in which an antenna is mounted. The housing may be formed of conductive materials. A dielectric window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. A proximity sensor adjacent to the dielectric window may be used in detecting external objects. The antenna may have an antenna resonating element that is mounted against an inner surface of a display cover glass layer. The antenna resonating element may be mounted to an upper surface of a plastic carrier. An electromagnetic shield may be mounted on a lower surface of the plastic carrier above the proximity sensor.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 conductive antenna ground structures; 
 a display having a planar cover layer; 
 an antenna resonating element adjacent to the planar cover layer, wherein the conductive antenna ground structures and the antenna resonating element form an antenna for the electronic device; 
 conductive structures that are electrically isolated from the conductive antenna ground structures; and 
 a planar conductive shield that is interposed between the antenna resonating element and the conductive structures and that shields the antenna resonating element from the conductive structures; and 
 an opaque layer interposed between the antenna resonating element and the planar cover layer. 
 
     
     
       2. The electronic device defined in  claim 1  further comprising a dielectric member interposed between the antenna resonating element and the planar conductive shield. 
     
     
       3. The electronic device defined in  claim 2  further comprising a biasing structure that biases the dielectric member and the antenna resonating element towards the planar cover layer. 
     
     
       4. The electronic device defined in  claim 3  wherein the biasing structure comprises foam and wherein the planar cover layer comprises a planar layer of display cover glass. 
     
     
       5. The electronic device defined in  claim 4  wherein the conductive antenna ground structures comprise portions of a conductive housing for the electronic device. 
     
     
       6. The electronic device defined in  claim 5  further comprising a dielectric window in the conductive housing. 
     
     
       7. The electronic device defined in  claim 6  further comprising foam that is interposed between the dielectric window and the planar conductive shield. 
     
     
       8. The electronic device defined in  claim 2  wherein the dielectric member comprises a plastic carrier. 
     
     
       9. The electronic device defined in  claim 8  wherein the antenna resonating element is attached to the plastic carrier with adhesive. 
     
     
       10. The electronic device defined in  claim 9  wherein the conductive antenna ground structures comprise portions of a conductive housing for the electronic device. 
     
     
       11. The electronic device defined in  claim 10  further comprising a dielectric window in the conductive housing. 
     
     
       12. The electronic device defined in  claim 11  wherein foam is interposed between the dielectric window and the planar conductive shield. 
     
     
       13. The electronic device defined in  claim 12  wherein the conductive shield comprises metal tape. 
     
     
       14. The electronic device defined in  claim 12  wherein the conductive structures comprise a proximity sensor electrode on the dielectric window. 
     
     
       15. The electronic device defined in  claim 2 , wherein the antenna resonating element is mounted on a first surface of the dielectric member and wherein the planar conductive shield is mounted on a second surface of the dielectric member. 
     
     
       16. The electronic device defined in  claim 1  wherein the conductive antenna ground structures include at least part of a tablet computer housing. 
     
     
       17. The electronic device defined in  claim 1 , wherein the planar conductive shield is electrically isolated from the conductive antenna ground structures. 
     
     
       18. The electronic device defined in  claim 1  wherein the conductive structures comprise a proximity sensor electrode. 
     
     
       19. The electronic device defined in  claim 18 , further comprising foam interposed between the proximity sensor electrode and the planar conductive shield. 
     
     
       20. The electronic device defined in  claim 1 , wherein the opaque layer comprises an opaque ink layer.

Description:
BACKGROUND 
     This relates generally to antennas, and, more particularly, to antennas for electronic devices. 
     Electronic devices such as portable computers and handheld electronic devices are becoming increasingly popular. Devices such as these are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry such as cellular telephone circuitry and short-range communications circuitry such as wireless local area network communications circuitry. Some devices are provided with the ability to receive other wireless signals such as Global Positioning System signals. 
     It can be difficult to incorporate antennas successfully into an electronic device. Some electronic devices are manufactured with small form factors, so space for antennas is limited. In many electronic devices, the presence of electronic components in the vicinity of an antenna serves as a possible source of electromagnetic interference. Antenna operation can also be disrupted by nearby conductive structures. Considerations such as these can make it difficult to implement an antenna in an electronic device that contains conductive housing walls or other conductive structures that can potentially block radio-frequency signals. 
     It would therefore be desirable to be able to provide improved antennas for wireless electronic devices. 
     SUMMARY 
     Antennas may be provided for electronic devices such as portable computers. An antenna may have an antenna resonating element that is mounted against an inner surface of a display cover glass layer in an electronic device. The electronic device may have a housing formed of conductive materials. A dielectric window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. 
     A capacitor electrode for a proximity sensor may be mounted in the vicinity of the antenna. For example, a capacitive proximity sensor electrode may be mounted adjacent to the dielectric window and may be used in detecting external objects. Proximity sensor measurements may be used in establishing limits on transmitted radio-frequency power. 
     The antenna resonating element may be mounted to an upper surface of a plastic carrier. An electromagnetic shield may be mounted on a lower surface of the plastic carrier above the proximity sensor. The electromagnetic shield may be interposed between the capacitor electrode and the antenna resonating element to shield the antenna resonating element from the capacitor electrode. 
     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 front perspective view of an illustrative electronic device with an antenna having a dielectric carrier member and a shield in accordance with an embodiment of the present invention. 
         FIG. 2  is a rear perspective view of an illustrative electronic device with an antenna having a dielectric carrier and a shield in accordance with an embodiment of the present invention. 
         FIG. 3  is a schematic diagram of an illustrative electronic device with antenna structures in accordance with an embodiment of the present invention. 
         FIG. 4  is a rear view of an illustrative electronic device having an antenna with a dielectric carrier structure and a conductive shielding structure in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of an illustrative electronic device having a proximity sensor electrode and having an antenna with a shield structure that interposed between the proximity sensor and an antenna resonating element in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of an illustrative electronic device having an antenna and wireless circuitry that may reduce the amount of power transmitted through the antenna when a proximity sensor detects that an external object is within a given range of the antenna and the electronic device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support wireless communications in one or more wireless communications bands. For example, the wireless communications circuitry may transmit and receive signals in cellular telephone bands and other communications bands. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to reduce the size of components that are used in these devices while providing enhanced functionality. Particularly in configurations in which an electronic device is used in transmitting and receiving radio-frequency signals in cellular telephone bands and other communications bands that have relatively wide bandwidths, it can be challenging to meet desired antenna performance criteria in a compact device. High transmit powers and wide antenna bandwidths can be desirable to ensure adequate signal strength during communications, but these attributes may give rise to challenges with controlling emitted radiation levels. 
     It is generally impractical to completely shield a user of an electronic device from transmitted radio-frequency signals. For example, conventional cellular telephone handsets generally emit signals in the vicinity of a user&#39;s head during telephone calls. Government regulations limit radio-frequency signal powers. For example, specific absorption rate (SAR) standards are in place in many jurisdictions that impose maximum energy absorption limits on handset manufacturers. At the same time, wireless carriers require that the user equipment that is used in their networks be capable of producing certain minimum radio-frequency powers so as to ensure satisfactory operation of the equipment. 
     One way to satisfy the demands of wireless carriers while complying with SAR standards involves use of proximity sensors to detect when an external object is in the presence of an antenna in an electronic device. When no external objects are present, the antenna can be operated over its full range of operating powers. When external objects are present, the maximum allowed transmit power for the antenna can be temporarily reduced to ensure that SAR limits are satisfied. 
     Space is at a premium in portable electronic devices and housings for these devices are sometimes constructed from conductive materials that block antenna signals. Arrangements in which antenna structures are formed behind an antenna window can help address these challenges. Antenna windows may be formed in conductive housing walls by forming a dielectric antenna window structure within an opening in the conductive housing wall. If desired, wireless signals can also be accommodate by forming all or most of the electronic device housing from a dielectric such as plastic. In some configurations, wireless signals can pass through dielectric structures such as the cover glass layers associated with a display. These configurations, other configurations for accommodating wireless signals in a device, or combinations of these configurations may be used in a wireless electronic device if desired. 
     An antenna resonating element for an antenna may be formed in the vicinity of an antenna window or under a portion of a display cover layer. Portions of the conductive housing or other conductive structures may serve as antenna ground. The antenna can be fed using a positive antenna feed terminal that is coupled to the antenna resonating element and a ground antenna feed terminal that is coupled to the conductive housing. During operation, radio-frequency signals for the antenna can pass through the antenna window or other non-conducting housing structures (e.g., part of the cover glass). 
     A proximity-based antenna power control circuit may be used to reduce near-field electromagnetic radiation intensities when the presence of an external object is detected in the vicinity of the antenna. The proximity-based antenna power control circuit may be based on a capacitive proximity sensor. Sensor electrodes for the capacitive proximity sensor may be placed in the vicinity of the antenna. 
     The antenna may be formed from an antenna resonating element and conductive portions of the housing or other conductive structures that serve as antenna ground. The antenna resonating element may be formed from conductive traces on a dielectric substrate. The conductive traces may be formed from copper or other metals. The dielectric substrate may be, for example, a rigid printed circuit board or a flexible printed circuit. Flexible printed circuits, which are sometimes referred to as flex circuits, have conductive traces formed on a flexible dielectric substrate such as sheets of polyimide or other polymers. 
     An antenna resonating element substrate may be mounted on a support structure. For example, an antenna resonating element substrate may be mounted on a dielectric carrier such as a molded plastic carrier. 
     The antenna resonating element and carrier may be mounted in the electronic device so that antenna signals can pass through the cover glass or other dielectric portions of the housing such as a dielectric window. A layer of foam or other biasing structures may be used to bias the antenna resonating element and carrier upwards against the interior surface of the cover glass. 
     A proximity sensor electrode or other conductive structure may be mounted within the housing under the carrier. The proximity sensor electrode may, for example, be mounted over a plastic antenna window. With this type of configuration, the distance between the proximity sensor electrode (or other such conductive structure) and the antenna resonating element may vary during manufacturing and use of the electronic device. For example, manufacturing variations and movement by a user during normal use may cause the foam that is used to bias the antenna resonating element and carrier upwards towards the cover glass to vary in thickness and thereby cause the separation between the antenna resonating element and the proximity sensor electrode to vary. Distance variations such as these have the potential to given rise to undesired antenna performance variations. 
     To address this source of possible antenna performance variations, conductive structures may be mounted to the underside of the carrier. Because the conductive structures are interposed between the antenna resonating element and the proximity sensor electrode, the conductive structures serve as an electromagnetic shield that tends to reduce the influence of the proximity sensor electrode on antenna performance. Incorporation of this shield into the antenna structures of device  10  therefore minimizes undesired performance variations in the antenna. The use of the carrier may also facilitate assembly and rework operations. 
     Antenna structures with configurations such as these can be mounted on any suitable exposed portion of a portable electronic device. For example, antennas can be provided on the front or top surface of the device. In a tablet computer, cellular telephone, or other device in which the front of the device is all or mostly occupied with conductive structures such as a touch screen display, it may be desirable to form at least part of the antenna window on a rear device surface. Other configurations are also possible (e.g., with antennas mounted in more confined locations, on device sidewalls, etc.). The use of antenna mounting locations in which at least part of a dielectric antenna window is formed in a conductive rear housing surface is sometimes described herein as an example, but, in general, any suitable antenna mounting location may be used in an electronic device if desired. 
     An illustrative portable device that may include antenna structures with carrier and shield structures is shown in  FIG. 1 . In general, devices such as device  10  of  FIG. 1  may be any suitable electronic devices with wireless communications capabilities such as desktop computers, portable computers such as laptop computers and tablet computers, handheld electronic devices such as cellular telephones, smaller portable electronic devices such as wrist-watch devices, pendant devices, headphone devices, and earpiece devices, or other wearable or miniature devices. 
     As shown in  FIG. 1 , device  10  may be a relatively thin device such as a tablet computer. Device  10  may have display such as display  50  mounted on its front (top) surface. Housing  12  may have curved portions that form the edges of device  10  and a relatively planar portion that forms the rear surface of device  10  (as an example). Housings with straight sidewalls and other configurations may also be used. The front surface of device  10  (i.e., the cover of display  50 ) may sometimes be referred to as forming the front housing surface of device  12 . 
     The cover of display  50  may be formed from a layer of cover glass, a layer of plastic, or other materials. The cover layer for display  50  may be radio transparent in its inactive edge region (i.e., away from the conductive portions of the display that include active pixel circuits). As a result, radio-frequency signals may be received by antenna structures that are mounted under an edge portion of the display cover layer and may be transmitted from the antenna structures through the edge portion of the display cover layer. In configurations in which housing  12  is formed form a metal or other conductive material, a dielectric window such as dielectric window  58  may be formed in housing  12 . Antenna structures for device  10  may be formed in the vicinity of dielectric window  58 , so that radio-frequency antenna signals can pass through dielectric window  58  (in addition to or instead of passing through the edge portions of the display cover layer). 
     Device  10  may have user input-output devices such as button  59 . Display  50  may be a touch screen display that is used in gathering user touch input. Capacitive touch sensors or other touch sensors for the display may be implemented using a touch panel that is mounted under a planar cover glass member on the surface of display  50 , may be integrated onto the cover glass layer, or may be otherwise incorporated into display  50 . 
     The central portion of display  50  (shown as region  56  in  FIG. 1 ) may be an active region that is sensitive to touch input and that is used in displaying images to a user using an array of image pixels (e.g., liquid crystal display image pixels, organic light-emitting diode image pixels, or other display pixels). The peripheral regions of display  50  such as regions  54  may be inactive regions that are free from touch sensor electrodes and image pixels. A layer of material such as an opaque ink may be placed on the underside of display  50  in peripheral regions  54  (e.g., on the underside of the cover glass). This layer may be transparent to radio-frequency signals. The conductive touch sensor electrodes in region  56  and the conductive structures associated with the array of image pixels in the display may tend to block radio-frequency signals. However, radio-frequency signals may pass through the cover glass and opaque ink in inactive display regions  54  (as an example). Radio-frequency signals may also pass through antenna window  58 . 
     Housing  12  may be formed from one or more structures. For example, housing  12  may include an internal frame and planar housing walls that are mounted to the frame. Housing  12  may also be formed from a unitary block of material such as a cast or machined block of aluminum. Arrangements that use both of these approaches may also be used if desired. 
     Housing  12  may be formed of any suitable materials including plastic, wood, glass, ceramics, metal, or other suitable materials, or a combination of these materials. In some situations, portions of housing  12  may be formed from a dielectric or other low-conductivity material, so as not to disturb the operation of conductive antenna elements that are located in proximity to housing  12 . In other situations, housing  12  may be formed from metal elements. An advantage of forming housing  12  from metal or other structurally sound conductive materials is that this may improve device aesthetics and may help improve durability and portability. 
     With one suitable arrangement, housing  12  may be formed from a metal such as aluminum or stainless steel. Portions of housing  12  in the vicinity of antenna window  58  may serve as antenna ground. Antenna window  58  may be formed from a dielectric material such as polycarbonate (PC), acrylonitrile butadiene styrene (ABS), a PC/ABS blend, or other plastics (as examples). Window  58  may be attached to housing  12  using adhesive, fasteners, or other suitable attachment mechanisms. To ensure that device  10  has an attractive appearance, it may be desirable to form window  58  so that the exterior surfaces of window  58  conform to the edge profile exhibited by housing  12  in other portions of device  10 . For example, if housing  12  has straight edges  12 A and a flat bottom surface, window  58  may be formed with a right-angle bend and vertical sidewalls. If housing  12  has curved edges  12 A, window  58  may have a similarly curved surface. 
       FIG. 2  is a rear perspective view of device  10  of  FIG. 1  showing how device  10  may have a relatively planar rear surface  12 B and showing how dielectric antenna window  58  may be rectangular in shape with curved portions that match the shape of curved housing edges  12 A (as an example). 
     A schematic diagram of device  10  showing how device  10  may include one or more antennas  26  and transceiver circuits that communicate with antennas  26  is shown in  FIG. 3 . As shown in  FIG. 3 , electronic device  10  may include storage and processing circuitry  16 . Storage and processing circuitry  16  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  16  may be used to control the operation of device  10 . Processing circuitry  16  may be based on a processor such as a microprocessor and other suitable integrated circuits. With one suitable arrangement, storage and processing circuitry  16  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, control functions for controlling radio-frequency power amplifiers and other radio-frequency transceiver circuitry, etc. Storage and processing circuitry  16  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using storage and processing circuitry  16  include internet protocols, cellular telephone 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, etc. 
     Input-output circuitry  14  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  18  such as touch screens and other user input interface are examples of input-output circuitry  14 . Input-output devices  18  may also include user input-output devices such as buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  10  by supplying commands through such user input devices. Display and audio devices may be included in devices  18  such as liquid-crystal display (LCD) screens, light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), and other components that present visual information and status data. Display and audio components in input-output devices  18  may also include audio equipment such as speakers and other devices for creating sound. If desired, input-output devices  18  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications circuitry  20  may include radio-frequency (RF) transceiver circuitry  23  formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  20  may include radio-frequency transceiver circuits for handling multiple radio-frequency communications bands. For example, circuitry  20  may include transceiver circuitry  22  that handles 2.4 GHz and 5 GHz bands for WiFi (IEEE 802.11) communications and the 2.4 GHz Bluetooth communications band. Circuitry  20  may also include cellular telephone transceiver circuitry  24  for handling wireless communications in cellular telephone bands such as the bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, and 2100 MHz band (as examples). Wireless communications circuitry  20  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  20  may include global positioning system (GPS) receiver equipment  21 , 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  20  may include antennas  26  such as an antenna or antennas located adjacent to antenna window  58  and under the inactive peripheral portion  54  of display  50 . Antennas  26  may be single band antennas that each cover a particular desired communications band or may be multiband antennas. A multiband antenna may be used, for example, to cover multiple cellular telephone communications bands. If desired, a dual band antenna may be used to cover two WiFi bands (e.g., 2.4 GHz and 5 GHz). A single band antenna may be used to receive Global Positioning System signals at 1575 MHz (as an example). Different types of antennas may be used for different bands and combinations of bands. For example, it may be desirable to form a dual band antenna for forming a local wireless link antenna, a multiband antenna for handling cellular telephone communications bands, and a single band antenna for forming a global positioning system antenna (as examples). 
     Transmission line paths  44  may be used to convey radio-frequency signals between transceivers  23  and antennas  26 . Radio-frequency transceivers such as radio-frequency transceivers  23  may be implemented using one or more integrated circuits and associated components (e.g., switching circuits, matching network components such as discrete inductors, capacitors, and resistors, and integrated circuit filter networks, etc.). These devices may be mounted on any suitable mounting structures. With one suitable arrangement, transceiver integrated circuits may be mounted on a printed circuit board. Paths  44  may be used to interconnect the transceiver integrated circuits and other components on the printed circuit board with antenna structures in device  10 . Paths  44  may include any suitable conductive pathways over which radio-frequency signals may be conveyed including transmission line path structures such as coaxial cables, microstrip transmission lines, etc. 
     Antennas  26  may, in general, be formed using any suitable antenna types. Examples of suitable antenna types for antennas  26  include antennas with resonating elements that are formed from patch antenna structures, inverted-F antenna structures, closed and open slot antenna structures, loop antenna structures, monopoles, dipoles, planar inverted-F antenna structures, hybrids of these designs, etc. With one suitable arrangement, which is sometimes described herein as an example, part of housing  12  (e.g., the portion of housing  12  in the vicinity of antenna window  58 ) may form a ground structure for the antenna associated with window  58 . Antenna ground structures may also be formed from conductive traces on printed circuit boards, internal housing members such as frame members and structural internal housing plates, conductive portions of components such as connectors, and other conductive structures. 
     A rear view of electronic device  10  in the vicinity of dielectric window  58  is shown in  FIG. 4 . The antennas in device  10  may each include an antenna resonating element and an antenna ground. For example, antenna  26  of  FIG. 4  may be formed from antenna resonating element  64  and nearby conductive structures such as portions of housing  12  that serve as antenna ground. Antenna resonating elements such as antenna resonating element  64  may overlap with antenna window  58 . 
     As shown in  FIG. 4 , antenna window  58  may extend along an edge of housing  12  in device  10  and may be large enough to accommodate one or more antennas  26 , each of which may include a corresponding antenna resonating element  64 . 
     Antenna resonating elements such as antenna resonating element  64  of  FIG. 4  may include conductive structures  62 . Conductive structures  62  may be formed from strips of metal, wires, portions of conductive housing members, or other conductive structures. With one suitable arrangement, which is sometimes described herein as an example, conductive structures  62  are formed from patterned conductive traces on a dielectric substrate such as substrate  60 . 
     Antenna resonating element substrate  60  may be formed from molded plastic, rigid printed circuit board layers (e.g., layers of fiber-glass-filled epoxy), flexible printed circuit board layers, etc. Flexible printed circuits (sometimes referred to a flex circuits) may be formed from flexible sheets of polymer such as polyimide. Conductive traces  62  may be formed on an antenna resonating element substrate layer to form a desired conductive pattern for an antenna resonating element. As shown in  FIG. 4 , for example, patterned conductive traces  62  may be formed in an inverted-F shape on substrate  60  (e.g., on a flex circuit substrate). Traces  62  may be formed from copper, gold, other metals, or combinations of these metals. 
     A cross-sectional side view of housing  12  showing how antenna resonating element  64  may be mounted under the surface of cover glass layer  60  is shown in  FIG. 5 . As shown in  FIG. 5 , antenna  26  may include antenna resonating element  64  and an antenna ground formed from conductive portions of housing  12  or other conductive structures. Antenna  26  may be fed using a feed terminal that is coupled to antenna resonating element  64  such as positive antenna feed terminal  76  and a ground antenna feed terminal that is coupled to housing  12  such as ground antenna feed terminal  78 . Transmission lines  44  may couple feed terminals  76  and  78  to radio-frequency transceiver circuitry  23  on printed circuit board  79 . 
     Antenna resonating element  64  may be placed in the vicinity of dielectric antenna window  58 , so that radio-frequency signals can be conveyed through window  58 . Radio-frequency signals can also be conveyed through a display cover member such as cover glass  60 . Display  50  may have an active region such as region  56  in which cover glass  60  has underlying conductive structure such as display panel module  90 . The structures in display panel  90  such as touch sensor electrodes and active display pixel circuitry may be conductive and may therefore attenuate radio-frequency signals. In region  54 , however, display  50  may be inactive (i.e., module  90  may be absent). An opaque layer such as opaque ink  61  may be formed on the underside of transparent cover glass  60  in region  54  to block antenna resonating element  68  from view. Ink  61  and the dielectric material of cover member  60  in region  54  may be sufficiently transparent to radio-frequency signals that radio-frequency signals can be conveyed through these structures during operation of device  10 . 
     Conductive structures such as conductive structures  66  may be located under antenna resonating element  64 . Conductive structures  66  may be, for example, one or more capacitor electrodes for a proximity sensor. These electrode structures may be formed from patterned metal traces on a flex circuit or other suitable substrate. As shown in  FIG. 5 , antenna resonating element  64  may be mounted on a support structure such as carrier  92 . Carrier  92  may be formed form a dielectric material such as plastic. Cavities may be formed in the plastic to facilitate fabrication using plastic molding equipment and to help lower the effective dielectric constant of carrier  92 . Although shown as having a rectangular cross section, carrier  92  may, if desired, have a cross-sectional shape with curved edges, a shape with non-parallel edges, or other suitable shape. In the dimension that extends along the edge of housing  12  (i.e., along the length of dielectric window  58  of  FIG. 4 ), carrier  92  may have straight edges (as an example). 
     Antenna resonating element substrate  60  of antenna resonating element  64  may be mounted to the upper surface of carrier  92  using adhesive  94  (as an example). A biasing structure such as one or more strips of elastomeric foam  98  may be formed under carrier  92 . Foam  98 , springs, or other suitable biasing structures may be used to press antenna resonating element  64  upwards in direction  100  against the lower surface of cover glass  60 . 
     Due to the close proximity between antenna resonating element  64  and conductive structures  66 , conductive structures  66  may serve as a parasitic antenna resonating element that influences the performance of antenna  26 . Due to manufacturing variations such as variations in the size of housing  12 , display  50 , and dielectric window  58 , there may be inherent variation in the distance D 2  between antenna resonating element  64  and conductive structures  66 . Variations in distance D 2  have the potential to lead to undesirable variations in the performance of antenna  26 . 
     To eliminate or at least reduce the influence of variations in the distance D 2  on the performance of antenna  26 , conductive shielding structures may be interposed between antenna resonating element  64  and conductive structures  66 . For example, a shield such as shield  96  may be formed on the lower surface of carrier  96 . Shield  96  may be formed from conductive materials such as metals. For example, shield  96  may be formed from a layer of aluminum or copper tape that is attached to carrier  92  with adhesive. Shield  96  may be electrically isolated from other structures in device  10  such as ground structures. This allows the thickness of carrier  92  to be minimized without unnecessarily restricting the bandwidth of antenna  26 . 
     Shield  96  serves to shield antenna resonating element  64  from conductive structures  66  and vice versa. The electromagnetic influence of conductive structures  66  is therefore effectively blocked by the presence of shield  96 , particularly when shield  96  has an area that is substantially equal to or larger than the area of structures  66 . As a result, conductive structures  66  have little or no influence on the performance of antenna  26  and variations in the distance D 2  between conductive structures  66  and antenna resonating element  64  do not significantly affect antenna performance. This reduces the susceptibility of antenna  26  to manufacturing variations. 
     The presence of shield  96  tends to influence the performance of antenna  26  (i.e., shield  96  serves as a parasitic antenna resonating element). Nevertheless, the distance D 1  between shield  96  and antenna resonating element  64  is fixed by the fixed thickness of carrier  92 . Although foam  98  may flex and manufacturing variations in display  50 , housing  12 , and antenna window  58  may give rise to variations in distance D 2  between conductive structures  66  and antenna resonating element  64 , the fixed thickness of carrier  92  fixes the distance D 1  between antenna resonating element  64  and shield  96 . Because distance D 1  is fixed and because the close proximity between shield  96  and antenna resonating element  64  causes shield  96  to be the dominant influence on the performance of antenna  26 , arrangements of the type shown in  FIG. 5  may help make antenna  26  resistant to undesired performance fluctuations. 
     Conductive structures  66  may be associated with conductive components (e.g., conductive electronic device components such as cameras, speakers, microphones, switches, connectors, sensors, light-emitting diodes, display components, etc.), portions of a device housing, or other conductive materials (e.g., other conductive structures that are electrically isolated from conductive housing  12 ). With one suitable arrangement, conductive structures  66  may be used in forming capacitor electrodes for a proximity sensor. 
     A circuit diagram showing how a proximity sensor signal may be used in controlling the amount of power that is transmitted by antenna  26  is shown in  FIG. 6 . As shown in  FIG. 6 , device  10  may include storage and processing circuitry  16  (see, e.g.,  FIG. 3 ). Device  10  may also include a proximity sensor such as proximity sensor  80 . Proximity sensor  80  may be implemented using any suitable type of proximity sensor technology (e.g., capacitive, optical, etc.). An advantage of capacitive proximity sensing techniques is that they can be relatively insensitive to changes in the reflectivity of external object  87 . 
     As shown in the example of  FIG. 6 , proximity sensor  80  may contain a capacitor electrode formed from a conductive member such as conductive member  66  ( FIG. 5 ). 
     Proximity sensor  80  may be mounted in housing  12  in the vicinity of antenna  26  (as shown in  FIG. 5 ) to ensure that the signal from proximity sensor  80  is representative of the presence of external object  87  in the vicinity of antenna  26  (e.g., within a distance D of antenna  26  and/or device  10 ). 
     Output signals from proximity sensor  80  may be conveyed to storage and processing circuitry  16  using path  86 . The signals from proximity sensor  80  may be analog or digital signals that provide proximity data to storage and processing circuitry  16 . The proximity data may be Boolean data indicating that object  87  is or is not within a given predetermined distance of antenna  26  or may be continuous data representing a current estimated distance value for D. 
     Storage and processing circuitry  16  may be coupled to transceiver circuitry  23  and power amplifier circuitry  82 . Dashed line  83  shows how received radio-frequency signals can be conveyed from antenna  26  to transceiver circuitry  23 . During data transmission operations, control lines  84  may be used to convey control signals from storage and processing circuitry  16  to transceiver circuitry  23  and power amplifier circuitry  82  to adjust output powers in real time. For example, when data is being transmitted, transceiver  23  and is associated output amplifier  82  can be directed to increase or decrease the power level of the radio-frequency signal that is being provided to antenna  26  over transmission line  44  to ensure that regulatory limits for electromagnetic radiation emission are satisfied. If, for example, proximity sensor  80  does not detect the presence of external object  87 , power can be provided at a relatively high (unrestricted) level. If, however, proximity sensor  80  determines that a user&#39;s leg or other body part or other external object  87  is in the immediate vicinity of antenna  26  (e.g., within 20 mm or less, within 15 mm or less, within 10 mm or less, etc.), storage and processing circuitry can respond accordingly by directing transceiver circuitry  23  and/or power amplifier  82  to transmit radio-frequency signals through antenna  26  at reduced powers. 
     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: 20110301
Publication Date: 20150210
Grant Date: 20150210
Priority Date: 20110301
Inventors: LI QINGXIANG
SCHLUB ROBERT W.
HAYES JONATHAN
VAZQUEZ ENRIQUE AYALA
WU YINGMENG
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 46752983