PATENT DOCUMENT

Publication Number: US-8610629-B2
Application Number: US-78940010-A
Country: US
Kind Code: B2

Title: Housing structures for optimizing location of emitted radio-frequency signals

Abstract:
Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. A display may be mounted on a front face of an electronic device. A conductive member such as a bezel may surround the display. Internal housing support structures such as a metal midplate member may be used to support the display. The midplate member may be connected between opposing edges of the bezel. The antenna structures may include an antenna formed from part of the midplate member and part of the bezel. Antenna image currents in the midplate member may be blocked by slots in the midplate member. The slots may be located adjacent to the antenna and may ensure that the antenna emits radio-frequency signals in a desired pattern. The slots may be angled and segmented.

Claims:
What is claimed is:  
     
       1. An electronic device, comprising:
 a rectangular housing having four edges; 
 an internal metal housing support structure that extends between an opposing pair of the edges, wherein the internal metal housing support structure has at least one opening that does not include any antennas; 
 a printed circuit board; and 
 an antenna formed from at least part of the metal housing support structure, wherein the antenna produces image currents in the internal metal housing support structure that are influenced by the at least one opening. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the at least one opening comprises a plurality of openings that influence the image currents. 
     
     
       3. The electronic device defined in  claim 2  wherein the openings comprise slots. 
     
     
       4. The electronic device defined in  claim 3  wherein the electronic device has a vertical longitudinal axis and a horizontal axis that is orthogonal to the vertical longitudinal axis and wherein the slots each have a respective longitudinal axis that is oriented diagonally with respect to the vertical axis and the horizontal axis. 
     
     
       5. The electronic device defined in  claim 1  wherein the at least one opening comprises a plurality of segmented slots, each slot having at least a first portion and a second portion separated by a break in which part of the metal housing support structure is present. 
     
     
       6. The electronic device defined in  claim 1  wherein the electronic device comprises a display and a conductive bezel that surrounds at least part of the display and wherein the antenna includes at least part of the conductive bezel. 
     
     
       7. The electronic device defined in  claim 1  wherein a conductive member runs along substantially all of the four edges, so that a dielectric region is formed between at least a given portion of the conductive member and the internal metal housing support structure and wherein the antenna is formed from the given portion of the conductive member and a portion of the internal metal housing support structure on an opposing side of the dielectric region. 
     
     
       8. The electronic device defined in  claim 7  wherein the internal metal housing support structure comprises a metal plate. 
     
     
       9. The electronic device defined in  claim 8  wherein the at least one opening comprises a plurality of slots in the plate. 
     
     
       10. The electronic device defined in  claim 8  wherein the at least one opening comprises a plurality of slots in the plate and wherein the electronic device further comprises:
 a display that rests on the plate and that is supported by the plate. 
 
     
     
       11. The electronic device defined in  claim 10  wherein the slots are oriented at a non-zero angle with respect to the edges and are segmented. 
     
     
       12. The electronic device defined in  claim 8  wherein the electronic device comprises a cellular telephone transceiver coupled to the antenna. 
     
     
       13. Antenna structures in an electronic device, comprising:
 a portion of a display bezel; and 
 a portion of an internal metal housing plate in the electronic device, wherein the internal metal housing plate is connected to the display bezel and comprises a plurality of slots that block image currents in the internal metal housing plate when antenna signals are transmitted by the antenna structures, and wherein the slots are surrounded and enclosed by the internal metal housing plate. 
 
     
     
       14. The antenna structures defined in  claim 13  wherein the slots comprise a plurality of elongated slots. 
     
     
       15. The antenna structures defined in  claim 14  wherein the slots are segmented slots having breaks. 
     
     
       16. The antenna structures defined in  claim 13  wherein the display bezel comprises a metal housing structure that has four edges that run along four respective sides of a rectangular display in the electronic device and wherein the internal metal housing plate comprises a planer metal support member that extends between an opposing pair of the edges and that supports the rectangular display. 
     
     
       17. An electronic device, comprising:
 a rectangular housing having four edges; 
 a conductive metal member that runs along the four edges of the rectangular housing; 
 a metal plate that is connected between a pair of opposing edges of the conductive metal member; and 
 an antenna formed at least partly from a portion of the conductive metal member and a portion of the metal plate, wherein the metal plate has a plurality of elongated slots adjacent to the antenna, and wherein the plurality of elongated slots are oriented at a non-zero angle with respect to the four edges of the rectangular housing. 
 
     
     
       18. The electronic device defined in claim  17  wherein the elongated slots have breaks and wherein the elongated slots block antenna image currents in the metal plate. 
     
     
       19. The electronic device defined in  claim 17  further comprising a display that overlaps the plurality of elongated slots and is supported by the metal plate. 
     
     
       20. The electronic device defined in  claim 19  wherein the metal plate and the portion of the conductive metal member are separated by a dielectric region and wherein the conductive metal member comprises a bezel that surrounds the display.

Description:
BACKGROUND 
     This relates generally to wireless communications circuitry, and more particularly, to electronic devices that have wireless communications circuitry. 
     Electronic devices such as handheld electronic devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. 
     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 to communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz (e.g., the main Global System for Mobile Communications or GSM cellular telephone bands). Long-range wireless communications circuitry may also handle the 2100 MHz band. Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. For example, electronic devices may communicate using the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth® band at 2.4 GHz. 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to implement wireless communications circuitry such as antenna structures using compact structures. At the same time, it may be desirable to form an electronic device from conductive structures such as conductive housing structures. Because conductive materials can affect radio-frequency performance, care must be taken when incorporating antenna resonating elements and other conductive structures into an electronic device. For example, antennas and associated conductive structures should be configured so that emitted radio-frequency signal powers remain below regulatory limits. 
     It would therefore be desirable to be able to provide improved antenna structures for electronic devices. 
     SUMMARY 
     An electronic device may be provided that has wireless communications circuitry. The wireless communications circuitry may include one or more antennas. The antennas may be formed from conductive structures within the electronic device. 
     The electronic device may be a portable electronic device with a rectangular housing. A display may be provided on the front surface of the housing. A conductive metal member such as a bezel may run along each of the four edges of the housing, surrounding the display. 
     Internal support structures such as an internal metal plate may be used to provide the electronic device with structural support. For example, an internal metal plate may be used to support the display. The internal metal plate may be connected to the conductive metal member along a pair of opposing edges. For example, the internal metal plate may be connected at least to left and right edges of the conductive metal member. 
     The conductive structures from which the antennas are formed may include portions of the conductive metal member and portions of the internal metal plate. For example, an antenna may be formed from a portion of the conductive metal member and a portion of the internal metal plate. These structures may be separated from each other by a dielectric region. 
     As the antenna operates, antenna currents may circulate around the dielectric region. At the same time, antenna image currents may be induced in the conductive metal member. The location of these antenna image currents can influence the location at which antenna signals are emitted from the electronic device. 
     Elongated slots (grooves) or other openings may be formed in the internal metal plate to adjust the location of emitted antenna signals. For example, a series of diagonally oriented segmented grooves may be formed in the internal metal plate that are adjacent to the antenna and the dielectric region. These slots may influence the location of antenna image currents during antenna operation. The inclusion of the grooves may help ensure that antenna signals are not emitted too near the center of the electronic device and satisfy regulatory limits on emitted antenna signal powers. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 4  is a top view of an electronic device showing how an internal housing structure such as a midplate member may be provided with openings such as angled grooves to adjust the pattern of radio-frequency antenna signals emitted from the electronic device in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram showing how the pattern with which radio-frequency signals are emitted into a specific anthropomorphic mannequin (SAM) phantom during device testing may be adjusted by incorporation of openings in an internal housing structure such as a midplate member in accordance with an embodiment of the present invention. 
         FIG. 6  is a top view of an electronic device showing an illustrative antenna that may be provided with ground plane openings such as internal housing structure grooves in accordance with an embodiment of the present invention. 
         FIG. 7  is a top view of an electronic device showing an illustrative pattern of vertical slots that may be provided in an internal housing support structure in accordance with an embodiment of the present invention. 
         FIG. 8  is a top view of an electronic device showing an illustrative pattern of zig-zag slots that may be provided in an internal housing support structure in accordance with an embodiment of the present invention. 
         FIG. 9  is a top view of an electronic device showing an illustrative pattern of segmented vertical slots and other openings that may be provided in an internal housing support structure in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an electronic device showing an illustrative pattern of square openings that may be provided in an internal housing support structure 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 multiple wireless communications bands. The wireless communications circuitry may include one or more antennas. 
     The antennas can be based on any suitable type of antenna architecture. For example, antenna structures can be formed from patch antennas, coil antennas, inverted-F antennas, planar inverted-F antennas, slot antennas, strip antennas, monopoles, dipoles, loop antennas, other suitable antennas, hybrid antennas that include structures associated with more than one of these antenna structure types, etc. 
     Antenna structures such as these may be provided in electronic devices such as desktop computers, game consoles, routers, laptop computers, etc. With one suitable configuration, these antenna structures may be provided in relatively compact electronic devices such as portable electronic devices. 
     An illustrative portable electronic device that may include antennas is shown in  FIG. 1 . Portable electronic devices such as illustrative portable electronic device  10  of  FIG. 1  may be laptop computers or small portable computers such as ultraportable computers, netbook computers, and tablet computers. Portable electronic devices such as device  10  may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. With one suitable arrangement, portable electronic device  10  may be a handheld electronic device such as a cellular telephone or music player. 
     Device  10  includes housing  12  and includes at least one antenna for handling wireless communications. Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, glass, ceramics, composites, metal, or other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material, so that the operation of conductive antenna elements that are located within housing  12  is not disrupted. In other situations, housing  12  may be formed from metal elements. 
     Device  10  may have a display such as display  14 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or other touch sensitive elements. Display  14  may include image pixels formed form light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electronic ink elements, liquid crystal display (LCD) components, or other suitable image pixel structures. A cover glass member may cover the surface of display  14 . Buttons such as button  19  and speaker ports such as speaker port  15  may be formed in openings in the cover glass. 
     Housing  12  may include sidewall structures such as sidewall structures  16 . Some or all of structures  16  may be formed using conductive materials. For example, structures  16  may be implemented using a conductive ring-shaped band member that substantially surrounds the rectangular periphery of display  14 . Structures  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming structures  16 . Structures  16  may serve as a bezel that holds display  14  to the front (top) face of device  10  and/or that serves as a cosmetic trim piece for display  14 . Structures  16  are therefore sometimes referred to as a bezel or as bezel structures. 
     It is not necessary for bezel  16  to have a uniform cross-section. For example, the top portion of bezel  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. If desired, the bottom portion of bezel  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). In the example of  FIG. 1 , bezel  16  has substantially straight vertical sidewalls. This is merely illustrative. The sidewalls of bezel  16  may be curved or may have any other suitable shape. 
     Portions of bezel  16  may be provided with gap structures. For example, bezel  16  may be provided with one or more gaps such as gap  18 , as shown in  FIG. 1 . Gap  18  lies along the periphery of the housing of device  10  and display  12  and is therefore sometimes referred to as a peripheral gap. Gap  18  may divide bezel  16  (i.e., so there is no conductive portion of bezel  16  in gap  18 ). 
     As shown in  FIG. 1 , gap  18  may be filled with dielectric. For example, gap  18  may be filled with air. To help provide device  10  with a smooth uninterrupted appearance and to ensure that bezel  16  is aesthetically appealing, gap  18  may be filled with a solid (non-air) dielectric such as plastic. Bezel  16  and gaps such as gap (and its associated plastic filler structure) may form part of one or more antennas in device  10 . For example, portions of bezel  16  and gaps such as gap  18  may, in conjunction with internal conductive structures, form one or more loop antennas. The internal conductive structures may include printed circuit board structures, conductive planar internal support members such as planar metal midplate members, conductive frame structures, or other suitable conductive structures. 
     In a typical scenario, device  10  may have upper and lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device  10  in region  22 . A lower antenna may, for example, be formed at the lower end of device  10  in region  20 . 
     Antennas in device  10  such as the antennas in regions  22  and  20  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications, Bluetooth® communications, etc. As an example, the lower antenna in region  20  of device  10  may be used in handling voice and data communications in one or more cellular telephone bands. 
     For satisfactory operation, the antennas of device  10  in regions  22  and  20  (e.g., the antenna structures formed from bezel  16  and internal conductive housing structures) should support the transmission and reception of radio-frequency antenna signals with desired efficiencies while simultaneously complying with regulatory limits for emitted powers. 
     These constraints can pose antenna design challenges. For example, image currents may be induced within internal conductive housing structures during operation of an antenna. Care should be taken to ensure that the image currents do not result in emitted radio-frequency signal powers that exceed regulatory limits. 
     With one suitable arrangement, grooves or other openings may be formed within the internal conductive housing structures of device  10  to control the distribution of image currents. This may help ensure that emitted radio-frequency signal powers comply with regulatory limits. 
     A schematic diagram of illustrative electronic components that may be used within device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, applications specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc. 
     Input-output circuitry  30  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  such as touch screens and other user input interface are examples of input-output circuitry  32 . Input-output devices  32  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 such as display  14  ( FIG. 1 ) and other components that present visual information and status data may be included in devices  32 . Display and audio components in input-output devices  32  may also include audio equipment such as speakers and other devices for creating sound. If desired, input-output devices  32  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     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, 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 circuits for handling multiple radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36  and  38 . Transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in cellular telephone bands such as the GSM bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, and the 2100 MHz data band (as examples). Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment, 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  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 structure, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link. 
     With one suitable arrangement, which is sometimes described herein as an example, the lower antenna in device (i.e., one of antennas  40  that is located in region  20  of device  10  of  FIG. 1 ) may be formed using a loop-type antenna design. 
     A cross-sectional side view of device  10  of  FIG. 1  taken is shown in  FIG. 3 . Display  14  may be mounted to the front surface of device  10 . 
     Display  14  may be mounted within device  10  using internal support structures. With one suitable arrangement, which is sometimes described herein as an example device  10  may be provided with one or more planar metal structural elements such as structure  52  on which display  14  may rest. Adhesive or fasteners may be used to mount display  14  on structure  52 . During use of display  14  (i.e., when a user presses on the surface of display  14  to make a touch screen selections), display  14  may tend to flex. By mounting display  14  so that display  14  rests on structure  52  and is supported by structure  52 , display  14  will be prevented from bending undesirably. Structure  52  may have an area that is substantially equal to that of display  14  or may be larger than that of display  14  (e.g., structure  52  may be a member that extends under substantially all of the planar area occupied by display  14  to prevent display  14  from flexing). 
     Structures  52  may extend across substantially all of the width of device  10  under display  14  (i.e., from the left edge of device  10  in  FIG. 1  to the opposing right edge of device  10  in  FIG. 1 ). Structure  52  may have a substantially planar shape. For example, structure  52  may have a substantially rectangular plate shape. Accordingly, structures such as illustrative structure  52  of  FIG. 3  may sometimes be referred to as a support plates, planar support structures, midplates, etc. Structure  52  (i.e., the midplate of device  10 ) may be formed from a sheet of metal such as stainless steel or aluminum (as examples). 
     Welds, solder, screws or other fasteners, engagement features such as springs and clips, adhesive (e.g., conductive adhesive), or other coupling mechanisms may be used to attach midplate  52  to bezel  16 . For example, midplate  52  may be welded to bezel  16  around some of the periphery of midplate  52 , where midplate touches bezel  16 . The presence of the midplate in device  10  may help strengthen device  10  and thereby protect the components of device  10  from damage. For example, midplate  52  may serve as a support for bezel  16 , display  14 , printed circuit boards, an audio jack and other connectors, and other components. The use of welds and other fastening mechanisms may electrically short midplate  52  to bezel  16 . 
     The outermost layers of display  14  may include structures such as image pixels formed from liquid crystal structures, thin-film transistors for controlling image pixels, touch sensor electrodes, and cover glass. Lower portions of display  14  such as layer  14 L may contain a reflector and other backlight structures. Many of these structures in display  14  (e.g., the structures shown in  FIG. 3 ) are conductive and can affect the way in which radio-frequency antenna signals are emitted from antenna  40  in region  20 . For example, a thin metal layer may be used as part of a rear reflector in backlight structures  14 L. The presence of these conductive display structures can affect antenna performance. 
     In a typical arrangement, antenna performance is more affected by the size and shape of midplate  52  than the size and shape of display  14 , because plate  52  is generally much more conductive than the conductive layers of display  14 . This is because midplate  52  is preferably formed from a relatively thick plate of metal (e.g., metal that is 0.1 to 3 mm thick, that is 0.2 to 2 mm thick, etc.). The metal that is used in forming midplate  52  may, for example, be stainless steel or aluminum. In an arrangement of this type, the presence of midplate  52  or other such conductive structural members should be taken into account, because the size, shape, and location of these structures are dominant factors in determining how the antennas of device  10  will perform. 
     In the illustrative arrangement shown in  FIG. 3 , a lower antenna for device  10  has been formed in region  20 . This lower antenna (i.e., one of antennas  40  of  FIG. 2 ) may be fed using an antenna feed having terminals such as positive antenna feed terminal  54  and ground (negative) antenna feed terminal  56 . The antenna may be formed using parts of housing  12  such as parts of conductive bezel  16  and parts of midplate  52 . Other conductive structures in device  10  such as printed circuit board traces and strips of metal may also affect antenna performance and may therefore be said to form part of the antenna. 
     A matching network may be used to help match the impedance of transmission line  58  to the antenna feed. Transmission line  58  may be, for example, a coaxial cable or a microstrip transmission line having an impedance of 50 ohms (as an example). The matching network may be formed from components such as inductors, resistors, and capacitors. These components may be provided as discrete components (e.g., surface mount technology components). Matching network components and antenna structures may also be formed from housing structures and other parts of device  10 . For example, gaps such as gap  18  ( FIG. 1 ) may affect antenna performance. 
     Device  10  may contain printed circuit boards such as printed circuit board  46 . Printed circuit board  46  and the other printed circuit boards in device  10  may be formed from rigid printed circuit board material (e.g., fiberglass-filled epoxy) or flexible sheets of material such as polymers. Flexible printed circuit boards (“flex circuits”) may, for example, be formed from flexible sheets of polyimide. 
     Printed circuit board  46  may contain interconnects such as interconnects  48 . Interconnects  48  may be formed from conductive traces (e.g., traces of gold-plated copper or other metals). Connectors such as connector  50  may be connected to interconnects  48  using solder or conductive adhesive (as examples). Integrated circuits, discrete components such as resistors, capacitors, and inductors, and other electronic components may be mounted to printed circuit board  46 . These components are shown as components  44  in  FIG. 3 . 
     Components  44  may include one or more integrated circuits that implement transceiver circuits  36  and  38  of  FIG. 2 . Connector  50  may be, for example, a coaxial cable connector that is connected to printed circuit board  46 . Cable  58  may be a coaxial cable or other transmission line. Terminal  54  may be connected to coaxial cable center connector  60 . Terminal  56  may be connected to a ground conductor in cable  58  (e.g., a conductive outer braid conductor) and may also be electrically connected to midplate  52 , so that portions of midplate  52  serve as antenna ground. 
     Region  62  between the lower edge of midplate  52  and the nearby portion of bezel  16  forms a dielectric region (opening) that separates part of bezel  16  and midplate  52 . With this type of arrangement, the part of bezel  16  and midplate  52  that surround the periphery of opening  62  may form a loop or slot antenna. Other antenna types may be formed in region  20  if desired. The use of loop or slot antenna formed from portions of bezel  16  and midplate  52  in region  20  of device  10  is merely illustrative. 
       FIG. 4  is a top view of device  10  showing how portions of midplate  52  and bezel  16  that surround opening  62  may form antenna  40  in region  20 . Midplate  52  is typically located within the interior of device  10 . In a completed product, covering layers such as a glass cover layer on the front planar surface of device  10  (as shown in  FIG. 1 ) and a dielectric layer such as plastic, glass, or ceramic on the rear planar surface of device  10  may be used to enclose midplate  52  and other internal housing structures within device  10 . Other materials may be used to form these covering structures if desired. An advantage of forming at least portions of the covering structures in the vicinity of antenna region  20  from dielectric is that this allows antenna signals to be conveyed to and from antenna  40 . 
     During antenna operation, radio-frequency antenna signals develop in the conductive structures of antenna  40 . For example, current I may develop within portion  52 L of midplate  52 , and bezel portions  16 C,  16 B, and  16 A. As shown in  FIG. 4 , portion  52 L of midplate  52  may be formed from a strip of midplate  52  that is adjacent to opening  62 . 
     Edge  52 L of midplate  52  may be considered to form the beginning of a relatively large ground plane (formed from the rest of midplate  52  and overlapping conductive structures such as display structures  14 ). Because of the presence of this ground plane, the flow of current I tends to induce a corresponding image current I′ in midplate  52 . The image current I′, which tends to circulate in the opposite direction from antenna current I is associated with emitted radio-frequency antenna signals (i.e., antenna image current I′ tends to form an image antenna in region  64 ). If not controlled, this image antenna can cause radio-frequency antenna signals to be emitted from device  10  in an undesired pattern. 
     To control the way in which radio-frequency antenna signals are emitted from antenna  40  during operation, midplate  54  may be provided with slots (grooves)  66  or other suitable openings in region  64 . The presence of these openings influences the flow of image currents I′ by blocking current flow where the openings are located. This helps ensure that radio-frequency antenna signals will only be emitted where desired. 
     In the example of  FIG. 4 , openings  66  have been formed by creating elongated slots (grooves) in midplate  52 , starting adjacent to region  52 L of midplate  52  and extending longitudinally along and parallel to diagonal axis  70 . Axis  70  may be oriented at any suitable angle relative to horizontal axis  72  (which represents the transverse axis of device  10 ) and vertical axis  74  (which represent the longitudinal axis of device  10 ). For example, axis  70  may be oriented at an angle A of 40° to 85° relative to horizontal axis  72 . Other types of configurations may be used for openings  66  if desired. The arrangement of  FIG. 4  is merely illustrative. 
     In general, openings  66  may be provided with any suitable shape that adjusts the flow of image current I′ and therefore controls the antenna signals emitted from antenna  40 . For example, openings  66  may be formed from circles, ovals, rectangles, other polygons, combinations of polygons and grooves, straight slots, angled slots, curved slots, slots with relatively wide widths (e.g., rectangles), slots with narrow widths (e.g., slots with widths of less than 2 mm, less than 1 mm, less than 0.2 mm, or less than 0.02 mm as examples), openings with compensations of curved and straight sides, etc. These openings need not be formed in overlapping structures such as display structures  14 , because the relatively larger conductivity of midplate  52  when compared to display structures  14  ensures that openings  66  in midplate  52  will have a dominating more influence on the pattern of antenna signals emitted from device  10 . If desired, however, openings such as openings  66  may be formed in other structures such as in other housing structures (e.g., in parts of bezel  16 , in parts of a planar conductive rear housing wall, in parts of internal frame structures other than midplate  52 , in display structures  14 , etc.). The arrangement of  FIG. 4  in which openings  66  are formed in midplate  52  is merely illustrative. 
     In the arrangement of  FIG. 4 , each slot  66  is segmented into two parts, separated by a respective break  68 . Breaks  68  represent solid portions of midplate  52  where the metal of midplate  52  has not been removed. The inclusion of breaks  68  may help reduce the image-current-blocking effects of slots  66 , so that image current I′ is not completely blocked (and so that antenna  40  retains a desired efficiency). Breaks  68  may also help preserve the structural integrity of midplate  52 , ensuring that midplate  52  and device  10  will be strong enough to withstand the types of impacts and drop events that sometimes occur during use of a portable electronic device. 
     The inclusion of openings  66  in midplate  52  may help move emitted radio-frequency signals to a desired location in device  10 . Consider, as an example, the testing setup of  FIG. 5 .  FIG. 5  is a front view of a specific anthropomorphic mannequin (SAM) phantom of the type that may be used during testing to ensure that device  10  complies with regulatory limits for emitted radio-frequency signal powers. 
     As shown in  FIG. 5 , devices such as device  10  are often used in a position in which an ear speaker port such as speaker port  15  rests against a user&#39;s ear (modeled using phantom ear structure  76 E). While device  10  is maintained in this typical test position, radio-frequency test equipment associated with phantom  76  may be used to measure how much radio-frequency signal power is emitted into phantom  76  from device  10 . 
     In region  78 , device  10  typically comes into contact with phantom  76 . At this point of contact, the front surface of device  10  (e.g., the outer cover glass associated with display  14 ) touches the surface of phantom  76 . A device with a midplate but no openings  66  might emit radio-frequency signals into absorption region  80 . Inclusion of grooves or other openings  66  in midplate  52  of the type shown in  FIG. 4  may cause device  10  to emit radio-frequency signals into absorption region  82 , rather than region  80 . 
     The signals that are absorbed in region  82  may have a lower power density than the signals that would have been absorbed in region  80 . This reduction in absorbed power may partly arise from the disruption in image current I′ that is created by including openings  66  in midplate  52 . The reduction in absorbed power may also partly arise from the increase in the distance between the surface of device  10  from which the antenna signals are emitted and the corresponding adjacent surface of phantom  76 . In the vicinity of absorption region  82  (which is lower down on device  10  and closer to end  40 ), there is more distance between the front surface of device  10  and the opposing surface of phantom  76  than in the vicinity of absorption region  80 . 
     Because the concentration of power in region  82  is lower than in region  80 , transmit signal strength may be increased in antenna  40  while still satisfying regulatory limits for absorbed radio-frequency signals. 
       FIG. 6  shows an illustrative feeding arrangement that may be used for antenna  40 . As shown in  FIG. 6 , antenna  40  may include components such as gap  18 , capacitor C (interposed in the antenna feed as a matching element), and conductive segment  84  (which helps tune antenna performance). The antenna structures and feed arrangement of  FIG. 6  are merely illustrative. Antenna  40  may be formed from any suitable antenna elements (e.g., patch antenna elements, wires, coils, inverted-F elements, planar inverted-F elements, monopoles, dipoles, strip antennas, slot antennas, loop antennas, antenna structures with combinations of these elements, etc.). 
       FIG. 7  is a top view of an illustrative configuration in which slots  66  extend vertically along axis  74 . Device  10  may be rectangular and may have a longitudinal axis that runs parallel to axis  74 . In this type of configuration, slots  66  may be oriented so that the longitudinal axis of each groove  66  is parallel to the longitudinal axis of device  10 . As shown in  FIG. 7 , slots  66  may be unsegmented (i.e., so that each slot has no breaks  68 ). If desired, vertically oriented slots  66  may also be provided with breaks. 
     In the illustrative configuration of  FIG. 8 , slots  66  have a zig-zag outline and have associated breaks  68 .  FIG. 9  shows an illustrative configuration for antenna  40  in which openings  66  have a combination of elongated groove shapes, oval shapes, and polygonal shapes such as rectangles. In the configuration of  FIG. 10 , midplate  52  has been provided with square openings  66 . If desired, other shapes can be used and combinations of these shapes may be used when providing midplate  52  with openings  66 . The arrangements of FIGS.  4  and  6 - 10  are presented as examples. 
     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. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20100527
Publication Date: 20131217
Grant Date: 20131217
Priority Date: 20100527
Inventors: PASCOLINI MATTIA
SCHLUB ROBERT W.
CABALLERO RUBEN
JIN NANBO
MYERS SCOTT
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 43835083