PATENT DOCUMENT

Publication Number: US-10727590-B2
Application Number: US-201815980511-A
Country: US
Kind Code: B2

Title: Electronic devices having interior antennas

Abstract:
An electronic device may have an upper housing with a display and a lower housing with a keyboard. The upper housing may rotate between open and closed positions. The lower housing may include a first conductive wall separated from the upper housing by an upper slot and a second conductive wall separated from the upper housing by a lower slot. An antenna resonating element may be mounted within the lower housing and may convey signals in low and high frequency bands through the lower slot when the upper housing closed. The resonating element may be grounded to the second conductive wall and may be separated from a conductive cavity wall by at least one-sixteenth of a wavelength in the low frequency band. A parasitic element may be used to redirect signals in the low frequency band towards and through the upper slot when the upper housing open.

Claims:
What is claimed is: 
     
       1. A portable computer, comprising:
 a housing having an upper housing portion that contains a display and having a lower housing portion, wherein the lower housing portion has opposing first and second conductive walls; 
 hinges that connect the upper housing portion to the lower housing portion, wherein the upper housing portion is configured to rotate relative to the lower housing portion between an open position and a closed position, and the upper housing portion is separated from the first conductive wall by a slot when the upper housing portion is in the open position; and 
 an antenna configured to transmit and receive radio-frequency signals through the slot, wherein the antenna comprises:
 an antenna resonating element mounted within the lower housing portion between the first and second conductive walls, and 
 a parasitic element mounted within the lower housing portion between the antenna resonating element and the slot. 
 
 
     
     
       2. The portable computer defined in  claim 1 , further comprising:
 a dielectric support structure mounted within the lower housing portion, wherein the antenna resonating element comprises conductive traces on the dielectric support structure. 
 
     
     
       3. The portable computer defined in  claim 2 , further comprising:
 an additional dielectric support structure mounted to the first conductive wall, wherein the parasitic element comprises conductive traces on the additional dielectric support structure. 
 
     
     
       4. The portable computer defined in  claim 3 , wherein the antenna is configured to transmit and receive the radio-frequency signals in a first frequency band and a second frequency band that is higher than the first frequency band, and the parasitic element is configured to resonate at frequencies in the first frequency band. 
     
     
       5. The portable computer defined in  claim 4 , wherein the parasitic element comprises an arm and a short circuit path that couples an end of the arm to the first conductive wall. 
     
     
       6. The portable computer defined in  claim 4 , wherein the first frequency band comprises frequencies between 2.4 GHz and 2.5 GHz and the second frequency band comprises frequencies between 4.9 GHz and 5.9 GHz. 
     
     
       7. The portable computer defined in  claim 2 , further comprising:
 conductive structures that couple the first conductive wall to the second conductive wall and that define a rear wall of a conductive cavity backing the antenna resonating element. 
 
     
     
       8. The portable computer defined in  claim 7 , wherein the conductive structures comprise:
 a sheet metal member; 
 a first conductive gasket that couples the sheet metal member to the first conductive wall; and 
 a second conductive gasket that couples the sheet metal member to the second conductive wall, wherein the dielectric substrate comprises an interior cavity having a first edge defined by the sheet metal member and a second edge defined by the dielectric substrate, an entirety of the conductive traces being formed at the second edge of the interior cavity. 
 
     
     
       9. The portable computer defined in  claim 2 , wherein the dielectric substrate comprises ventilation port openings that serve as airflow passageways for a cooling system in the lower housing portion. 
     
     
       10. The portable computer defined in  claim 2 , wherein the upper housing portion is separated from the second conductive wall by an additional slot when the upper housing portion is in the closed position and the antenna is configured to transmit and receive the radio-frequency signals through the additional slot when the upper housing is in the closed position. 
     
     
       11. The portable computer defined in  claim 10 , wherein the second conductive wall comprises a lip that extends beyond the dielectric support structure and that defines an edge of the additional slot. 
     
     
       12. The portable computer defined in  claim 11 , wherein the antenna further comprises:
 a positive antenna feed terminal coupled to the antenna resonating element and a ground antenna feed terminal coupled to the second conductive wall; and 
 a return path coupled between the antenna resonating element and the second conductive wall. 
 
     
     
       13. The portable computer defined in  claim 12 , further comprising:
 conductive structures that couple the first conductive wall to the second conductive wall and that define a rear wall of a conductive cavity, wherein the antenna resonating element is backed by the conductive cavity, the antenna is configured to transmit and receive the radio-frequency signals in a given frequency band through the additional slot when the upper housing portion is in the closed position, and the rear wall is located at a cavity depth from the antenna resonating element, the cavity depth being at least one-sixteenth of a wavelength corresponding to a frequency in the given frequency band. 
 
     
     
       14. A portable computer comprising:
 a metal housing having an upper housing portion that contains a display and having a lower housing portion, wherein the lower housing portion has opposing first and second conductive walls; 
 hinges that connect the upper housing portion to the lower housing portion, wherein the upper housing portion is configured to rotate relative to the lower housing portion between an open position and a closed position, and the upper housing portion is separated from the second conductive wall by a slot when the upper housing portion is in the closed position; 
 conductive structures in the lower housing portion that short the first conductive wall to the second conductive wall; 
 a dielectric substrate that is mounted within the lower housing portion and that is located between the conductive structures and the slot; and 
 an antenna resonating element on the dielectric substrate and interposed between the first and second conductive walls, wherein the antenna resonating element is configured to convey radio-frequency signals in a given frequency band through the slot when the upper housing portion is in the closed position, the antenna resonating element is located at a given distance from the conductive structures, and the given distance is at least one-sixteenth of a wavelength corresponding to a frequency in the given frequency band. 
 
     
     
       15. The portable computer defined in  claim 14 , wherein the given distance is between one-sixteenth and one-quarter of the wavelength. 
     
     
       16. The portable computer defined in  claim 15 , wherein the antenna resonating element is configured to convey the radio-frequency signals in an additional frequency band that is higher than the given frequency band through the slot when the upper housing portion is in the closed position. 
     
     
       17. The portable computer defined in  claim 16 , wherein the second conductive wall comprises a protruding portion that extends beyond an edge of the dielectric substrate and that defines an edge of the slot, further comprising:
 a ground antenna feed terminal coupled to the second conductive wall; 
 a positive antenna feed terminal coupled to the antenna resonating element; 
 a return path coupled between the antenna resonating element and the second conductive wall; 
 radio-frequency transceiver circuitry; and 
 a radio-frequency transmission line that couples the radio-frequency transceiver circuitry to the positive antenna feed terminal and the ground antenna feed terminal. 
 
     
     
       18. A portable computer comprising:
 a metal base housing containing a keyboard, wherein the metal base housing comprises first and second conductive walls; 
 a metal lid containing a display; 
 hinges that couple the metal lid to the metal base housing, wherein the metal lid is separated from the first conductive wall by an upper slot and is separated from the second conductive wall by a lower slot; 
 an antenna resonating element that is mounted within the metal base housing between the first and second conductive walls and that is configured to transmit radio-frequency signals through the lower slot; and 
 a parasitic antenna resonating element that is configured to redirect at least some of the transmitted radio-frequency signals through the upper slot. 
 
     
     
       19. The portable computer defined in  claim 18 , wherein the transmitted radio-frequency signals comprise radio-frequency signals in a 2.4 GHz wireless local area network (WLAN) frequency band, and the antenna resonating element is further configured to transmit additional radio-frequency signals through the upper and lower slots in a 5 GHz WLAN frequency band. 
     
     
       20. The portable computer defined in  claim 19 , wherein the parasitic antenna resonating element is mounted to the first conductive wall and comprises a conductive arm that is configured to resonate at frequencies in the 2.4 GHz WLAN frequency band.

Description:
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 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. The upper housing may rotate between an open position and a closed position. 
     The lower housing may have opposing first and second conductive walls. The first conductive wall may be separated from the upper housing by an upper slot. The second conductive wall may be separated from the upper housing by a lower slot. The electronic device may include wireless communications circuitry such as an antenna. The antenna may include an antenna resonating element mounted entirely within the lower housing and between the first and second conductive walls. The antenna resonating element may be formed on a dielectric substrate that is recessed into the lower housing away from the slots. In order to reduce the width of the lower slot, the second conductive wall may include a protruding portion that extends beyond an edge of the dielectric substrate. 
     The antenna may convey radio-frequency signals in a 5 GHz frequency band through the lower slot when the upper housing is in the closed position and through the upper and lower slots when the upper housing is in the open position. Conductive structures such as a sheet metal member may be formed in the lower housing and may short the first conductive wall to the second conductive wall. The conductive structures may form a cavity back for the antenna resonating element. The antenna resonating element may be located at a cavity depth from the conductive structures. The cavity depth may be between one-sixteenth and one-quarter of a wavelength corresponding to a frequency in a 2.4 GHz frequency band. The antenna resonating element may have a return path coupled to the second conductive wall. The antenna may be fed using an antenna feed with a ground antenna feed terminal coupled to the second conductive wall. 
     The antenna may include a parasitic antenna resonating element mounted to the first conductive wall. The parasitic antenna resonating element may be configured to resonate in the 2.4 GHz frequency band. The parasitic antenna resonating element may redirect radio-frequency signals in the 2.4 GHz frequency band from the lower slot towards and through the upper slot when the upper housing is in the open position. The antenna may thereby operate with satisfactory antenna efficiency across two or more frequency bands regardless of whether the upper housing is in the open or closed positions. 
    
    
     
       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 diagram of an illustrative inverted-F antenna in accordance with an embodiment. 
         FIG. 4  is a diagram showing hinge and flexible printed circuit structures bridging a gap between upper and lower housings in a laptop computer of the type shown in  FIG. 1  in accordance with an embodiment. 
         FIG. 5  is a perspective view of a dielectric substrate having ventilation port openings and antenna resonating element in accordance with an embodiment. 
         FIG. 6  is a cross-sectional side view of an illustrative rear portion of the lower housing of a laptop computer showing how antenna structures may operate at multiple frequencies through a slot between the lower housing and an upper housing in accordance with an embodiment. 
         FIG. 7  is a cross-sectional side view of an illustrative rear portion of the lower housing of a laptop computer showing how antenna structures may operate at multiple frequencies through multiple slots between the lower housing and an upper housing in accordance with an embodiment. 
         FIG. 8  is a side view of an illustrative parasitic antenna resonating element that may be formed in antenna structures of the type shown in  FIGS. 6 and 7  in accordance with an embodiment. 
         FIG. 9  is a graph in which antenna performance (antenna efficiency) has been plotted as a function of frequency for a laptop computer placed in a closed lid configuration in accordance with an embodiment. 
         FIG. 10  is a graph in which antenna performance (antenna efficiency) has been plotted as a function of frequency for a laptop computer placed in an open lid configuration in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of a dielectric substrate that supports an antenna resonating element mounted between conductive housing walls of an electronic device 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® or other wireless personal area network (WPAN) bands and the 2.4 GHz and 5 GHz Wi-Fi® band or other wireless local area network (WLAN) 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 may include planar portions and/or portions that form one or more cavities for cavity-backed antennas. In addition to portions of housing  12 , the cavities in the cavity-backed antennas may be formed from metal brackets, sheet metal members, and other internal metal structures, and/or metal traces on dielectric structures (e.g., plastic structures) in device  10 . Metal traces may be formed on dielectric structures using molded interconnect device techniques (e.g., techniques for selectively plating metal traces onto regions of a plastic part that contains multiple shots of plastic with different affinities for metal), using laser direct structuring techniques (e.g., techniques in which laser light exposure is used to activate selective portions of a plastic structure for subsequent electroplating metal deposition operations), or using other metal trace deposition and patterning techniques. 
     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 cameras, microphones, speakers, buttons, 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. Connector 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 a 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 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  such as hinges  26 A and  26 B that are located at opposing left and right sides of housing  12  along rotational axis  22  (sometimes referred to herein as hinge axis  22 ). A slot-shaped opening such as opening  20  may be formed between upper housing  12 A and lower housing  12 B and may be bordered on either end by hinges  26 A and  26 B. Opening  20  may sometimes be referred to herein as gap  20  or slot  20  between upper housing  12 A and lower housing  12 B. Hinges  26 A and  26 B, 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. Slot  20  extends along the rear edge of lower housing  12 B parallel to axis  22 . The lateral plane of upper housing (lid)  12 A and the lateral plane of lower housing  12 B may be separated by an angle that varies between 0° when the lid is closed to 90°, 140°, 160°, or more when the lid is fully opened. 
     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 storage and processing circuitry such as control circuitry  30 . Control 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 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, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Control 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, control circuitry  30  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  30  include 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, and other wireless communications protocols. 
     Device  10  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, accelerometers, proximity sensors, and other sensors and input-output components. 
     Device  10  may include wireless communications circuitry  34  that allows control circuitry  30  of device  10  to communicate wirelessly with external equipment. The external equipment with which device  10  communicates wirelessly may be a computer, a cellular telephone, a watch, a router or other wireless local area network equipment, a wireless base station in a cellular telephone network, a display, or other electronic equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry  48  and one or more antennas such as antenna  40 . Configurations in which device  10  contains a single antenna may sometimes be described herein as an example. 
     If desired, device  10  may be supplied with a battery such as battery  36 . Control circuitry  30 , input-output devices  32 , wireless communications circuitry  34 , and power management circuitry associated with battery  36  may produce heat during operation. To ensure that these components are cooled satisfactorily, device  10  may be provided with a cooling system such as cooling system  38 . Cooling system  38 , which may sometimes be referred to as a ventilation system, may include one or more fans and other equipment for removing heat from the components of device  10 . Cooling system  38  may include structures that form airflow ports (e.g., openings in ventilation port structures located along slot  20  of  FIG. 1  or other portions of device  10  through which cool air may be drawn by one or more cooling fans and through which air that has been warmed from heat produced by internal components may be expelled). Airflow ports, which may sometimes be referred to as cooling ports, ventilation ports, air exhaust and entrance ports, etc., may be formed from arrays of openings in plastic ventilation port structures or other structures associated with cooling system  38 . 
     Radio-frequency transceiver circuitry  48  and antenna(s)  40  may be used to handle one or more radio-frequency communications bands. For example, circuitry  48  may include wireless local area network transceiver circuitry that may handle a 2.4 GHz band for WiFi® and/or Bluetooth® communications and, if desired, may include 5 GHz transceiver circuitry (e.g., for WiFi®). If desired, transceiver circuitry  48  and antenna(s)  40  may handle communications in other bands (e.g., cellular telephone bands, near field communications bands, bands at millimeter wave frequencies, etc.). 
     Antenna(s)  40  in wireless communications circuitry  34  may be formed using any suitable types of antenna. For example, an antenna for device  10  may include a resonating element that is formed from a loop antenna structure, a patch antenna structure, an inverted-F antenna structure, a slot antenna structure, a planar inverted-F antenna structure, a helical antenna structure, a hybrid of these structures, etc. If desired, device  10  may include cavity-backed antennas (e.g., cavity-backed inverted-F antennas in which a conductive cavity backs an inverted-F antenna resonating element and serves to optimize the gain and directionality of the inverted-F antenna resonating element, cavity-backed slot antennas, cavity-backed monopole antennas, cavity-backed loop antennas, etc.). Control circuitry  30 , input-output devices  32 , wireless communications circuitry  34 , and other components of device  10  may be mounted in device housing  12  ( FIG. 1 ). 
     As shown in  FIG. 2 , transceiver circuitry  48  in wireless communications circuitry  34  may be coupled to antennas such as antenna  40  using paths such as transmission line path  50  (sometimes referred to herein as radio-frequency transmission line  50 ). Transmission line paths in device  10  such as transmission line  50  may include coaxial cables, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, waveguide transmission lines (e.g., coplanar waveguides, grounded coplanar waveguides, etc.), transmission lines formed from combinations of transmission lines of these types, etc. 
     Transmission line paths in device  10  such as transmission line  50  may be integrated into rigid and/or flexible printed circuit boards if desired. In one suitable arrangement, transmission line paths in device  10  may include transmission line conductors (e.g., signal and/or ground conductors) that are integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that maintain a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Transmission line  50  in device  10  may be coupled to antenna feed  42  of antenna  40 . Antenna  40  of  FIG. 2  may, for example, form an inverted-F antenna, a planar inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed such as antenna feed  42  with a positive antenna feed terminal such as positive antenna feed terminal  44  and a ground antenna feed terminal such as ground antenna feed terminal  46 . Transmission line  50  may include a positive transmission line conductor  52  (sometimes referred to herein as signal conductor  52 ) and a ground transmission line conductor  54  (sometimes referred to herein as ground conductor  54 ). Signal conductor  52  may be coupled to positive antenna feed terminal  44  and ground conductor  54  may be coupled to ground antenna feed terminal  46 . Other types of antenna feed arrangements may be used (e.g., indirect feed arrangements, feed arrangements in which antenna  40  is fed using multiple feeds, etc.) and multiple antennas  40  may be provided in device  10 , if desired. The feeding configuration of  FIG. 2  is merely illustrative. 
     Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within transmission line  50 , in or between parts of antenna  40 , or in other portions of wireless communications circuitry  34 , if desired. Control circuitry  30  may be coupled to transceiver circuitry  48  and input-output devices  32 . During operation, input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . Control circuitry  30  may use wireless communications circuitry  34  to transmit and receive wireless signals. 
       FIG. 3  is a schematic diagram of an illustrative antenna for device  10 . In the example of  FIG. 3 , antenna  40  is an inverted-F antenna having inverted-F antenna resonating element  58  and antenna ground  56  (sometimes referred to herein as ground plane  56 , ground structures  56 , antenna ground structures  56 , or ground  56 ). Antenna resonating element  58  (sometimes referred to herein as antenna radiating element  58 , resonating element  58 , or radiating element  58 ) may have a main resonating element arm such as arm  60 . If desired, antenna resonating element  58  may have multiple branches (e.g., a first branch formed from arm  60 , a second branch formed from arm  60 ′, etc.). The lengths of each of the branches of antenna resonating element  58  may be selected to support communications band resonances at desired frequencies (e.g., a high band resonance may be supported using a shorter branch such as arm  60 ′ and a low band resonance may be supported using a longer branch such as arm  60 ). Antenna resonances may also be produced from resonating element harmonics and/or using parasitic antenna resonating elements. 
     As shown in  FIG. 3 , antenna resonating element  58  (e.g., arm  60 ) may be coupled to antenna ground  56  by return path  62 . Antenna feed  42  may be coupled between arm  60  and antenna ground  56  in parallel with return path  62 . Positive antenna feed terminal  44  may be coupled to arm  60 . Ground antenna feed terminal  46  may be coupled to antenna ground  56 . Antenna ground  56  may be formed from metal portions of housing  12  (e.g., portions of lower housing  12 B of  FIG. 1 ), metal traces on a printed circuit or other carrier, internal metal bracket members, sheet metal members, metal foil, and/or other conductive structures in device  10 . 
     Metal traces on one or more flexible printed circuits may bisect slot  20  of  FIG. 1 . Consider, for example, the illustrative configuration of device  10  that is shown in  FIG. 4 . In the example of  FIG. 4 , upper housing  12 A is separated from lower housing  12 B by air-filled slot  20 . Hinges  26 A and  26 B may be coupled between housings  12 A and  12 B along the respective left and right edges of device  10 . One or more flexible printed circuits such as flexible printed circuit  64  may bisect slot  20  along the length of slot  20 , thereby creating two slots (i.e., two separate slot-shaped portions of slot  20 ) such as slots  20 - 1  and  20 - 2 . Flexible printed circuit  60  may contain one or more sheets of flexible dielectric substrate material such as a layer of polyimide or a sheet of other flexible polymers. 
     Flexible printed circuit  60  may include signal lines  70  for routing display signals (i.e., data signals associated with displaying images on display  14  of  FIG. 1 ) and other signals (e.g., camera signals, backlight signals, power signals, touch sensor signals, etc.) between upper housing  12 A and lower housing  12 B. Ground traces  66  may be provided on the outer edges of flexible printed circuit  64  (i.e., in flexible printed circuit  64 , signal lines  70  may be flanked on opposing sides by ground traces  66 ). Ground traces  66  may be formed from copper or other metal and may have any suitable widths (e.g., 1 mm to 3 mm, less than 1 mm, more than 1 mm, etc.). Ground traces  66  may be shorted to metal housings  12 A and  12 B using screws, other fasteners, welds, conductive adhesive, solder, or other conductive coupling mechanism (see, e.g., conductive ground connections  68 ). 
     With this type of arrangement, slots (openings)  20 - 1  and  20 - 2  may be surrounded by metal. For example, slots  20 - 1  and  20 - 2  may be surrounded by metal portions of upper housing  12 A and lower housing  12 B on their top and bottom edges. Hinges  26 A and  26 B and ground traces  66  may also be formed from metal and may help define the shapes of slots  20 - 1  and  20 - 2 . As shown in  FIG. 4 , slot  20 - 1  may have a left edge formed by hinge  26 A and an opposing right edge formed from the ground traces on flexible printed circuit  64 . Slot  20 - 2  may have a left edge formed from flexible printed circuit  64  and an opposing right edge formed from hinge  26 -B. The example of  FIG. 4  in which one flexible printed circuit divides slot  20  into two separate slots is merely illustrative. If desired, two or more flexible printed circuits may divide slot  20  into three or more separate slots. Two or more separate flexible printed circuits may divide slot  20  into two separate slots  20 - 1  and  20 - 2  if desired (e.g., two or more separate flexible printed circuits may be interposed between slots  20 - 1  and  20 - 2 ). 
     During wireless operation of device  10 , slots  20 - 1  and  20 - 2  may serve as antenna apertures for respective electrically isolated antennas  40  in lower housing  12 B of device  10 . For example, a first antenna  40  may be mounted within lower housing  12 B and aligned with slot  20 - 1  and a second antenna  40  may be mounted within lower housing  12 B and aligned with slot  20 - 2 . Conductive structures in lower housing  12 B may form cavity structures for each of the antennas  40  (e.g., cavity-shaped ground structures or other ground structures that form part of antenna ground  56  of  FIG. 3 ). By aligning antennas  40  with separate slots between lower housing  12 B and upper housing  12 A in device  10 , the antennas may exhibit sufficient electrical isolation from each other (e.g., such that the antennas may be used to form a multiple-input-multiple-output (MIMO) antenna array at 2.4 GHz and/or 5 GHz and/or other suitable frequencies for wireless local area network communications, etc.). 
     Device  10  may have ventilation port structures such as ventilation port structures  72  mounted along the rear edge of lower housing  12 B or elsewhere in device  10 . Ventilation port structures  72  may have arrays of openings that form ventilation ports. Fans in cooling system  38  ( FIG. 2 ) may be used to draw air into lower housing  12 B through the openings and may be used to exhaust air that has been warmed by the circuitry in lower housing  12 B through the openings. Separate ventilation port structures  72  may be aligned with slots  20 - 1  and  20 - 2  if desired. For example, a first ventilation port structure  72  may be interposed between the antenna  40  aligned with slot  20 - 1  and hinge  26 A whereas a second ventilation port structure  72  is interposed between the antenna  40  aligned with slot  20 - 2  and hinge  26 B. In another suitable arrangement, ventilation port structures  72  may be interposed between antennas  40  and flexible printed circuit  64 . If desired, multiple antennas  40  may be aligned with slot  20 - 1  and/or multiple antennas  40  may be aligned with slot  20 - 2 . 
     If desired, a given antenna  40  and a given ventilation port structure  72  may be formed on a common (shared) substrate mounted within lower housing  12 B.  FIG. 5  is a perspective view showing how antenna  40  and ventilation port structure  72  may be formed on the same dielectric support structure such as substrate  74 . Substrate  74  may be formed dielectric material such as plastic, foam, ceramic, glass, rubber, or any other desired dielectric materials. Substrate  74  may be mounted along the rear edge of lower housing  12 B adjacent to slot  20 - 1  or slot  20 - 2  of  FIG. 4 . Substrate  74  may be mounted within the interior of lower housing  12 B (e.g., between a conductive upper wall and a conductive lower wall of lower housing  12 B, where keyboard  16  and track pad  18  of  FIG. 1  are formed in the conductive upper wall of lower housing  12 B). 
     As shown in  FIG. 5 , antenna resonating element  58  (e.g., arm  60 , arm  60 ′, and return path  62 ) for antenna  40  may be formed from conductive material on front surface  82  of substrate  74 . As an example, antenna resonating element  58  may be formed from conductive traces on front surface  82  of substrate  74 . Return path  62  of antenna resonating element  58  may extend to bottom surface  84  of substrate  74 . 
     If desired, a conductive layer such as conductive layer  80  may be formed on bottom surface  84  of substrate  74 . Conductive layer  80  may be formed from conductive brackets, conductive gaskets, conductive springs, conductive fasteners, conductive screws, conductive pins, a sheet metal layer, conductive adhesive, solder, welds, conductive foam, conductive traces, metal foil, combinations of these, and/or any other desired conductive material on bottom surface  84  of substrate  74 . While referred to herein as conductive layer  80 , the conductive material in conductive layer  80  may have a substantially planar shape, may have planar and non-planar portions, or may have a non-planar shape, for example. Positive antenna feed terminal  44  of antenna feed  42  may be coupled to arm  60  and ground antenna feed terminal  46  of antenna feed  42  may be coupled to conductive layer  80 . Return path  62  may be coupled to (e.g., galvanically connected to) conductive layer  80  such that conductive layer  80  forms part of antenna ground  56  ( FIG. 3 ) for antenna  40 . Return path  62  may be soldered or welded to conductive layer  80 , may be coupled to conductive layer  80  using conductive interconnect structures, or may be formed from an integral portion of conductive layer  80  (e.g., antenna resonating element  58  and conductive layer  80  may be formed from a single continuous conductor if desired). 
     Conductive layer  80  may be coupled to (e.g., shorted to) the conductive lower wall of lower housing  12 B. For example, when substrate  74  is mounted within lower housing  12 B ( FIGS. 1 and 4 ), conductive layer  80  may be in contact with the conductive lower wall of lower housing  12  or may be coupled to the conductive lower wall using any desired conductive interconnect structures (e.g., solder, welds, conductive adhesive, conductive clips, conductive foam, conductive brackets, conductive screws, etc.). In this way, conductive layer  80  and the conductive lower wall of lower housing  12 B may both form a portion of antenna ground  56  for antenna  40  ( FIG. 3 ). 
     This is merely illustrative and, if desired, conductive layer  80  may be omitted. In these scenarios, ground antenna feed terminal  46  and return path  62  may be coupled directly to the conductive lower wall of lower housing  12 B or to conductive material such as a sheet metal layer located between bottom surface  84  of substrate  74  and the conductive lower wall (e.g., using conductive interconnect structures such as solder, welds, conductive adhesive, conductive wire, conductive foam, conductive brackets, conductive screws, combinations of these, etc.). Portions of the feed path for antenna feed  42  and portions of return path  62  may be formed using vias that pass through substrate  74  if desired. Metal traces used in forming conductive layer  80  and/or antenna resonating element  58  may be formed on dielectric substrate  74  using molded interconnect device techniques (e.g., techniques for selectively plating metal traces onto regions of a plastic part that contains multiple shots of plastic with different affinities for metal), using laser direct structuring techniques (e.g., techniques in which laser light exposure is used to activate selective portions of a plastic structure for subsequent electroplating metal deposition operations), or using other metal trace deposition and patterning techniques. 
     As shown in  FIG. 5 , ventilation port structure  72  may have ventilation port openings  76  in substrate  74 . Openings  76  may extend from front surface  82  of substrate  74  to the opposing rear surface of substrate  74  or to any other desired surface of substrate  74 . Openings  76  may be used to allow air to enter the interior of lower housing  12 B, as shown by arrow  86 , and/or to exit the interior of lower housing  12 B, as shown by arrow  88 . Substrate  74  may include any desired number of openings  76  arranged in any desired pattern (e.g., one or two-dimensional arrays of 6-20 openings, more than four openings, fewer than 30 openings, etc.). Each array of openings  76  may form a different respective ventilation port in device  10 . For example, a first array of openings  76  on a substrate  74  aligned with slot  20 - 1  of  FIG. 4  may form first ventilation port whereas a second array of openings  76  on a substrate  74  aligned with slot  20 - 2  may form a second ventilation port. If desired, the first ventilation port may be used to allow air to enter the interior of lower housing  12 B whereas the second ventilation port is used to allow air to exit the interior of lower housing  12 B. 
     The example of  FIG. 5  in which antenna  40  and openings  76  are formed on separate portions of front surface  82  is merely illustrative. If desired, arm  60  of antenna resonating element  60  may extend along front surface  82  between two or more openings  76  (e.g., between two horizontal rows of openings  76 ). If desired, arm  60  may include a portion  78  that extends into one or more openings  76 . Portion  78  of arm  60  may serve to increase the length of arm  60  (e.g., to tune a frequency response of antenna  40 ). Portions of arm  60  may be formed from conductive vias in substrate  74  if desired. 
     Antenna resonating element arms  60  and  60 ′ may allow antenna  60  to support radio-frequency communications in multiple frequency bands. The length of antenna resonating element arm  60 , arm  60 ′, and return path  62  may be selected so that antenna  40  radiates with a satisfactory antenna efficiency within one or more desired frequency bands of interest. For example, the length from the tip of arm  60  through return path  62  may be approximately equal to one quarter of an effective wavelength at a first desired operating frequency for antenna  40  (e.g., a frequency in the 2.4 GHz WLAN or WPAN band). The length from the tip of arm  60 ′ through return path  62  may be approximately equal to one quarter of an effective wavelength at a second desired operating frequency for antenna  40  (e.g., a frequency in the 5.0 GHz WLAN band). These effective wavelengths may be offset from free space wavelengths by a factor associated with the dielectric constant of substrate  74 . Harmonic modes of arm  60  and/or arm  60 ′ may also support communications in these or additional frequency bands if desired. 
     The example of  FIG. 5  is merely illustrative. If desired, antenna resonating element  58  may have additional arms or branches for covering additional bands. Additional antennas  40  may be formed on substrate  74 . Substrate  74  may have any desired shape and any desired number of sides (e.g., any desired shape having one or more curved and/or straight sides). Antenna resonating element  58  may have straight and/or curved edges and may have any desired shape (e.g., any desired shape following one or more curved and/or straight paths). Other types of antennas may be used if desired. Antenna resonating element  58  may extend onto two or more sides of substrate  74  if desired. Substrate  74  may be hollow and may include one or more interior cavities. In these scenarios, antenna resonating element  58  may be formed on surfaces of the interior cavities if desired. Ventilation port structure  72  may be omitted from substrate  74  in another suitable arrangement (e.g., antenna  40  may be formed on a dedicated antenna substrate or may be formed on a substrate that supports other device components). 
     Substrate  74  may be mounted within the interior of lower housing  12 B.  FIGS. 6 and 7  are cross-sectional side views of device  10  in the vicinity of the rear edge of lower housing  12 B (e.g., showing substrate  74  mounted within lower housing  12 B from the direction of arrow  89  of  FIG. 5 ). In the illustrative configurations of  FIGS. 6 and 7 , slot  20  between upper housing  12 A and lower housing  12 B ( FIG. 1 ) includes upper and lower portions (in addition to the left and right portions  20 - 1  and  20 - 2  located at different positions along axis  22  as shown in  FIG. 4 ). Antenna signals can pass through either the upper portion of slot  20  (shown in  FIGS. 6 and 7  as upper slot  20 T), through the lower portion of slot  20  (shown in  FIGS. 6 and 7  as lower slot  20 L), or through both upper slot  20 T and lower slot  20 L. 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 or through both slots. 
       FIG. 6  is a cross-sectional side view of device  10  in the vicinity of the rear edge of lower housing  12 B when upper housing  12 A is in a closed position (sometimes referred to herein as a closed lid configuration). As shown in  FIG. 6 , lower housing  12 B may include a conductive upper wall  12 B- 1  and an opposing conductive lower wall  12 B- 2 . The lateral surface of conductive upper wall  12 B- 1  may extend parallel or substantially parallel (e.g., within 30 degrees) to the lateral surface of conductive lower wall  12 B- 2 . Conductive upper wall  12 B- 1  and conductive lower wall  12 B- 2  may define the interior of lower housing  12 B. A main logic board, battery  36  ( FIG. 2 ), a set of input-output devices  32 , cooling system  38 , transceiver circuitry  48 , control circuitry  30 , and other desired components may be mounted within the interior of lower housing  12 B. Substrate  74  may be mounted within the interior of lower housing  12 B between conductive upper wall  12 B- 1  and conductive lower wall  12 B- 2 . By mounting substrate  74  in this way, an entirety of antenna resonating element  58  ( FIG. 5 ) and substrate  74  may be interposed between conductive upper wall  12 B- 1  and conductive lower wall  12 B- 2  within the interior of lower housing  12 B. This may, for example, hide antenna  40  from view of a user at the exterior of device  10  and may protect antenna  40  from contaminants or damage. 
     Components such as keyboard  16  and track pad  18  ( FIG. 1 ) may operate through openings in conductive upper wall  12 B- 1 . Conductive lower wall  12 B- 2 , which may be joined to conductive upper wall  12 B- 1  around the lateral periphery of lower housing  12 B (e.g., such that conductive material surrounds the interior cavity and thus substrate  74 ), may have feet or other support structures that allow device  10  to rest on a table top, a user&#39;s lap, or other support structure during operation. When device  10  is being used in this way, air may flow in and out of ventilation port structure  72  through openings  76  in substrate  74  ( FIG. 5 ). 
     Fans and other cooling system structures (structures in cooling system  38  of  FIG. 2 ) may be mounted within the interior of lower housing  12 B (e.g., to the left of substrate  74  as shown in  FIG. 6 ). Ventilation port structure  72  in substrate  74  may allow (intake) air to pass from the right of substrate  74  to the left of substrate  74  (e.g., as shown by arrow  86  of  FIG. 5 ) and/or may allow (exhaust) air to pass from the left of substrate  74  to the right of substrate  74  (e.g., as shown by arrow  88  of  FIG. 5 ). 
     As shown in  FIG. 6 , conductive upper wall  12 B- 1  may be electrically coupled to conductive lower wall  12 B- 2  using conductive structures  105 . Conductive structures  105  may include sheet metal, metal foil, integral portions of lower housing  12 B, conductive adhesive, solder, welds, conductive springs, conductive gaskets, conductive traces on rear surface  104  of substrate  74 , and/or any other desired conductive structures. Conductive structures  105 , conductive upper wall  12 B- 1 , and conductive lower wall  12 B- 2  may form a conductive cavity that backs antenna  40  within lower housing  12 B. Conductive structures  105  may form a rear wall of the conductive cavity (whereas conductive walls  12 B- 1  and  12 B- 2  form side walls of the conductive cavity). Conductive structures  105  may sometimes be referred to herein as rear wall  105 , conductive cavity rear wall  105 , conductive wall  105 , or conductive shielding structure  105 . Substrate  74  may extend from its front surface  82  to conductive structures  105  (e.g., the conductive cavity may be filled by substrate  74 ) or may only fill part of the conductive cavity. The conductive cavity may serve to enhance gain and directionality of the radio-frequency signals handled by antenna  40  (e.g., the dimensions and boundaries of the conductive cavity may be selected to direct radio-frequency signals radiated by antenna resonating element arm  60  in one or more directions with a desired gain). 
     Conductive structures such as structures  112  and  110  may be used to ground conductive traces on substrate  74  to lower housing  12 B. Structures  112  and  110  may each include layers of conductive adhesive, conductive foam layers that help press substrate  74  upwards and/or downwards so that substrate  74  is held in place between conductive upper wall  12 B- 1  and conductive lower wall  12 B- 2 , conductive gaskets (e.g., conductive gaskets formed from conductive foam, conductive fabric, a solid elastomeric conductive material, or other conductive material), conductive pins, conductive screws, solder welds, conductive wires, conductive springs, combinations of these, and/or any other desired conductive structures. Structures  112  may, for example, be used to couple grounded traces on top surface  90  of substrate  74  to conductive upper wall  12 B- 1  (e.g., so that conductive upper wall  12 B- 1  forms a part of antenna ground  56  of  FIG. 3 ). If desired, conductive structures  112  may be coupled to conductive structures  105  (e.g., conductive structures  112  may short traces on substrate  74  to conductive lower wall  12 B- 2  through conductive structures  105 ). Structures  110  may, for example, be used to couple grounded traces on substrate  74  to conductive lower wall  12 B- 2  (e.g., so that conductive lower wall  12 B- 2  forms a part of antenna ground  56  of  FIG. 3 ). Structures  110  and  112  may, if desired, be used to mechanically secure substrate  74  in place within lower housing  12 B and/or to protect the interior of lower housing  12 B from dirt or other contaminants. 
     Radio-frequency transmission line  50  may be coupled to antenna feed terminals  44  and  46  of antenna  40  (e.g., signal conductor  52  of transmission line  50  may be coupled to positive antenna feed terminal  44  whereas ground conductor  54  is coupled to ground antenna feed terminal  46 ). Signal conductor  52  and/or ground conductor  54  may be formed from a coaxial cable path that extends through an opening or cavity within substrate  74 , may include conductive vias that extend through substrate  74 , may include conductive traces on substrate  74 , and/or may include any other desired conductive structures. Positive antenna feed terminal  44  may be coupled to antenna resonating element arm  60 . Ground antenna feed terminal  46  may be coupled directly to conductive lower wall  12 B- 2 , to grounded conductive traces on lower surface  92  of substrate  74 , or to conductive structures  110 , as examples. Return path  62  of antenna  40  may couple antenna resonating element arm  60  to conductive lower wall  12 B- 2 , to grounded conductive traces on lower surface  92  of substrate  74 , or to conductive structures  110 . Return path  62  may include conductive traces on substrate  74 , conductive wire, conductive pins, conductive vias, and/or any other desired conductive structures. If desired, antenna  40  may include a parasitic antenna resonating element such as parasitic antenna resonating element  108  (sometimes referred to herein as parasitic element  108 ). Parasitic element  108  may be formed on a dielectric support structure such as dielectric substrate  106 . 
     Conductive structures  105 , conductive structures  112 , and/or conductive structures  110  may short conductive upper wall  12 B- 1  to conductive lower wall  12 B- 2  and may serve to electromagnetically isolate antenna  40  from components within the interior of lower housing  12 B. 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. Similarly, these components help ensure that operation of circuitry in the interior of device  10  does not interfere with radio-frequency operations performed by antenna  40 . Conductive structures  105  may cover some or all of rear surface  104  of substrate  74  and may, if desired, have ports to accommodate air flow through openings  76  in substrate  74  ( FIG. 5 ). 
     When arranged in this way, antenna resonating element arm  60  and front surface  82  of dielectric substrate  74  may face upper slot  20 T and lower slot  20 L so that radio-frequency antenna signals from antenna  40  may pass through upper slot  20 T and lower slot  20 L. Upper housing  12 A may have a display portion in which display  14  is located. Display  14  and the display portion of upper housing  12 A extend substantially parallel to conductive upper wall  12 B- 1  when upper housing  12 A is in the closed position over lower housing  12 B. Upper housing  12 A may have a rear portion such as rear portion  114  that extends from an end of display  14 . If desired, rotational axis  22  of device  10  may extend through rear portion  114  (e.g., into the page of  FIG. 6 ). Upper housing  12 A may rotate around axis  22  when moved between a closed lid position and an open lid position. Rear portion  114  of upper housing  12 A has an end  94  that opposes display  14 . End  94  may extend at a non-parallel angle with respect to the segment of rear portion  114  through which axis  22  passes, if desired (e.g., end  94  may form a “lip” of upper housing  12 A that protrudes towards lower housing  12 B). 
     Rear portion  114  of upper housing  12 A is separated from conductive lower wall  12 B- 2  by lower slot  20 L. As shown in  FIG. 6 , lower slot  20 L may have a width (thickness)  98  when upper housing  12 A is in the closed lid position. Width  98  may be greater than the width of upper slot  20 T in the closed lid position such that the majority of the radio-frequency signals handled by antenna  40  pass through lower slot  20 L, as shown by arrow  96 . In practice, lower slots  20 L having greater widths  98  may be more unsightly and less aesthetically pleasing than lower slots  20 L having smaller widths  98 . In addition, it is easier for foreign objects such as a portion of a user&#39;s clothing, a user&#39;s body, or other external objects to become lodged or stuck within lower slot  20 L in scenarios where lower slot  20 L has a greater width  98  than in scenarios where lower slot  20 L has a smaller width  98 . It may therefore be desirable to be able to provide device  10  with relatively narrow lower slots  20 L. 
     In order to minimize the width  98  of lower slot  20 L, conductive lower wall  12 B- 2  may include a protruding portion  100  (sometimes referred to herein as protruding lip  100 , lip  100 , shelf  100 , ledge  100 , or extension  100 ). Protruding portion  100  may extend beyond front surface  82  of substrate  74  by length  102  (e.g., protruding portion  100  may have a length  102  and substrate  74  may be separated from lower slot  20 L by length  102 ). In other words, substrate  74  may be recessed within lower housing  12 B by length  102 . As examples, width  98  may be between 2.0 and 2.5 mm, between 2.2 and 2.3 mm, between 1.5 and 3.0 mm, between 1.0 mm and 4.0 mm, less than 5 mm, less than 5.3 mm, between 0.5 mm and 5.3 mm, etc. Length  102  may be between 1.0 mm and 2.0 mm, between 2.0 mm and 3.0 mm, between 1.0 mm and 3.0 mm, between 0.5 mm and 4.0 mm, between 0.25 mm and 5.0 mm, or any other desired length. When configured in this way, lower slot  20 L may have a satisfactory width for optimizing the aesthetic appearance of device  10  and minimizing the risk of foreign objects becoming stuck within lower slot  20 L. 
     At the same time, if care is not taken, recessing substrate  74  into lower housing  12 B and constraining width  98  of lower slot  20 L can make it more difficult to convey radio-frequency signals between antenna  40  and external wireless equipment via lower slot  20 L. This can serve to limit the overall antenna efficiency of antenna  40 , particularly in scenarios where antenna  40  covers multiple frequency bands. For example, if care is not taken, the antenna may exhibit satisfactory antenna efficiency within a 5.0 GHz frequency band while exhibiting unsatisfactory antenna efficiency within a 2.4 GHz frequency band. In another possible arrangement, ground antenna feed terminal  46  and return path  62  of antenna  40  may be coupled to conductive upper wall  12 B- 1  instead of conductive lower wall  12 B- 2 . However, in this scenario, the antenna may exhibit satisfactory antenna efficiency within the 2.4 GHz frequency band while exhibiting unsatisfactory antenna efficiency within the 5.0 GHz frequency band. 
     Coupling the feed for antenna  40  and return path  62  to conductive lower wall  12 B- 2  (as shown in  FIG. 6 ) may serve to optimize transmission and reception through lower slot  20 L in the 5.0 GHz frequency band. In particular, grounding antenna  40  in this way may shift current hot spots in the 5.0 GHz frequency band towards conductive lower wall  12 B- 2 , thereby pushing the electric field distribution of antenna  40  in the 5.0 GHz frequency band closer to the location of lower slot  20 L and allowing lower slot  20 L to pass a satisfactory amount of radio-frequency signals in the 5.0 GHz frequency band. In order to recover wireless performance in the lower 2.4 GHz frequency band, antenna resonating element arm  60  may be mounted within lower housing  12 B so that it is separated from conductive structures  105  by a selected distance  116  (sometimes referred to herein as cavity depth  116  or cavity thickness  116  of the conductive cavity backing antenna resonating element arm  60 ). In general, larger cavity depths  116  may allow for greater antenna efficiency within the 2.4 GHz frequency band than shallower cavity depths (while also consuming greater volume within device  10 ). In this way, some of the volume within lower housing  12 B that would otherwise be available to other device components may be sacrificed in order to increase cavity depth  116  to a level that supports satisfactory antenna efficiency in the 2.4 GHz frequency band. 
     In order to support satisfactory antenna efficiency in the 2.4 GHz frequency band, cavity depth  116  may be selected to be at least one-sixteenth of the wavelength of operation of antenna  40  (e.g., an effective wavelength corresponding to a frequency in the 2.4 GHz frequency band when offset to compensate for the dielectric constant of substrate  74 ). If desired, antenna performance in the 2.4 GHz frequency band may be balanced with volume consumption in device  10  by selecting cavity depth  116  to be between one-sixteenth and one-half of the wavelength of operation of antenna  40 , between one-half and three-quarters of the wavelength of operation, between one-half and one-quarter of the wavelength of operation, between one-sixteenth and one-quarter of the wavelength of operation, approximately equal to (e.g., within 15% of) one-eighth of the wavelength of operation, or approximately equal to one-quarter of the wavelength of operation, as examples (e.g., between 5 and 15 mm, between 10 and 12 mm, between 24 and 30 mm, between 20 and 40 mm, between 5 and 20 mm, between 3 and 35 mm, etc.). Substrate  74  may have a thickness (extending from front surface  82  to rear surface  104 ) that is approximately equal to cavity depth  116  or may have a thickness that is less than cavity depth  116  (e.g., in scenarios where substrate  74  does not extend all the way to conductive structures  105 ). In this way, antenna  40  may convey radio-frequency signals through lower slot  20 L while upper housing  12 A is in the closed lid position with satisfactory antenna efficiency in both relatively low and relatively high frequency bands such as the 2.4 GHz and the 5.0 GHz frequency bands. 
       FIG. 7  shows device  10  in an illustrative lid-open configuration in which upper housing  12 A has been rotated into an open position about rotational axis  22 . In practice, varying the position of upper housing  12 A with respect to lower housing  12 B may alter the widths of upper slot  20 T and lower slot  20 L. As shown in  FIG. 7 , upper slot  20 T has a greater width when upper housing  12 A is in the open position than when it is in the closed position ( FIG. 6 ). At the same time, lower slot  20 L may have a width  119  when upper housing  12 A is in the open position. Width  119  may be even smaller than width  98  of  FIG. 6 . This decrease in lower slot width may have little or no effect on antenna performance in the 5.0 GHz frequency band. Antenna  40  may therefore convey radio-frequency signals in the 5.0 GHz frequency band through lower slot  20 L and/or upper slot  20 T regardless of the position of upper housing  12 A. However, opening upper housing  12 A (i.e., shortening the width of lower slot  20 L) reduces the amount of radio-frequency energy that can be conveyed through lower slot  20 L in the 2.4 GHz frequency band. If care is not taken, this can deteriorate antenna efficiency in the 2.4 GHz frequency band to potentially unsatisfactory levels when upper housing  12 A is in the open position. 
     In order to mitigate this deterioration in 2.4 GHz performance, parasitic element  108  may be coupled to conductive upper wall  12 B- 1  of lower housing  12 B. Parasitic element  108  may, for example, be formed on a dielectric support structure such as substrate  106  that is mounted to conductive upper wall  12 B- 1  at or adjacent to upper slot  20 T. Substrate  106  may include plastic, ceramic, adhesive, combinations of these, and/or any other desired dielectric materials. Parasitic element  108  may be formed from conductive traces on substrate  106 , a sheet metal member, metal foil, an integral portion of conductive upper wall  12 B- 1 , or any other desired conductive structures. 
     Parasitic element  108  may have a length that is selected so that parasitic element  108  resonates in the lower frequency band covered by antenna  40  (e.g., in the 2.4 GHz frequency band). In this way, parasitic element  108  may strengthen the electromagnetic field associated with antenna  40  at the location of upper slot  20 T, effectively shifting radiation in the 2.4 GHz frequency band from lower slot  20 L towards and through upper slot  20 T (as shown by arrow  120 ). In other words, parasitic element  108  may effectively redirect radio-frequency energy that would otherwise be radiated towards lower slot  20 L through upper slot  20 T instead. This may serve to increase antenna efficiency in the 2.4 GHz band to satisfactory levels when upper housing  12 A is in the open position. 
     The example of  FIG. 7  is merely illustrative. In general, parasitic element  108  may be coupled to conductive upper wall  12 B- 1  at any desired location between substrate  74  and upper slot  20 T (e.g., parasitic element  108  may be interposed between arm  60  and upper slot  20 T or between substrate  74  and upper slot  20 T). If desired, substrate  106  and substrate  74  may be formed from a single integral dielectric substrate (e.g., parasitic element  108  may be formed on an extension of dielectric substrate  74 ). Parasitic element  108  may be coupled to other support structures (e.g., support structures that are not mounted to conductive upper wall  12 B- 1 ) or may be formed without any dielectric support structures if desired. Dielectric substrate  106  may be used to support other device components such as flexible printed circuit  64  of  FIG. 4  if desired. 
       FIG. 8  is a front view of parasitic element  108  mounted within lower housing  12 B of device  10  (e.g., as taken in the direction of arrow  122  of  FIG. 7 ). As shown in  FIG. 8 , parasitic element  108  may include one or more conductive arms such as arms  126  and  124  on substrate  106 . Arm  126  may be coupled to conductive upper wall  12 B- 1 . For example, arm  126  (sometimes referred to herein as short path or return path  126 ) may be coupled to conductive upper wall  12 B- 1  using solder, welds, conductive adhesive, or other materials. In another suitable arrangement, arm  126  and arm  124  are formed from an integral extension of conductive upper wall  12 B- 1 . 
     Arm  124  may extend from the end of arm  126  (e.g., in a non-parallel direction with respect to the longitudinal axis of arm  126 ). Parasitic element  108  may have a length  128  (e.g., from the base of arm  126  at conductive upper wall  12 B- 1  to the opposing tip of arm  124 ). Length  128  may be selected to be approximately equal to (e.g., within 15% of) one-quarter of a wavelength of operation of antenna  40  (e.g., a wavelength corresponding to a frequency in a relatively low frequency band such as the 2.4 GHz frequency band). This length may be adjusted to compensate for the dielectric constant of substrate  106  if desired. This length may be tweaked to adjust the amount of radio-frequency energy in the 2.4 GHz frequency band that is redirected from lower slot  20 L towards and through upper slot  20 T ( FIG. 7 ). 
     In the example of  FIG. 8 , parasitic element  108  is an “L-shaped” parasitic element, with arm  126  extending perpendicular to arm  124  (e.g., where arm  124  extends parallel to the lateral surface of conductive upper wall  12 B- 1 ). This is merely illustrative and, in general, parasitic element  108  may have any desired shape (e.g., any desired shape having curved and/or straight edges and following any desired path such as a meandering path or paths having curved and/or straight segments). Parasitic element  108  may include any desired number of arms or branches. If desired, antenna  40  may include multiple parasitic elements  108  on substrate  106 . 
     In the illustrative graph of  FIG. 9 , antenna efficiency has been plotted as a function of frequency for scenarios in which upper housing  12 A is placed in the closed position (e.g., as shown in  FIG. 6 ). Curve  130  corresponds to an antenna arrangement in which ground antenna feed terminal  46  and return path  62  are connected to conductive upper wall  12 B- 1  instead of conductive lower wall  12 B- 2 . As shown by curve  130 , forming the antenna in this way allows for a relatively high antenna efficiency in a low frequency band such as the 2.4 GHz frequency band while exhibiting a relatively low (e.g., unsatisfactory) antenna efficiency in a relatively high band such as the 5.0 GHz frequency band. 
     Curve  132  corresponds to an antenna arrangement in which ground antenna feed terminal  46  and return path  62  are coupled to conductive lower wall  12 B- 2 , but where the conductive cavity formed by conductive structures  105  has insufficient cavity depth (e.g., where cavity depth  116  of  FIG. 6  is less than one-sixteenth of the wavelength corresponding to a frequency in the 2.4 GHz frequency band). As shown by curve  132 , forming the antenna in this way allows for a relatively high antenna efficiency in the 5.0 GHz frequency band while exhibiting a relatively low (e.g., unsatisfactory) antenna efficiency in the 5.0 GHz frequency band. 
     Curve  134  corresponds to the antenna arrangement shown in  FIG. 6  (e.g., where ground antenna feed terminal  46  and return path  62  are coupled to conductive lower wall  12 B- 2  and where antenna  40  is provided with a sufficiently large cavity depth  116 ). As shown by curve  134  of  FIG. 9 , forming the antenna in this way allows for a relatively high antenna efficiency in both the 5.0 GHz frequency band and the 2.4 GHz frequency band through lower slot  20 L while upper housing  12 A is in the closed position. 
     In the illustrative graph of  FIG. 10 , antenna efficiency has been plotted as a function of frequency for scenarios in which upper housing  12 A is placed in the open position (e.g., as shown in  FIG. 7 ). Curve  136  corresponds to an antenna arrangement in which parasitic  108  and protruding portion  100  of conductive lower wall  12 B- 2  are omitted. In this arrangement, slot  20 L is provided with a relatively large width such as 5.0 mm or greater and the surface of substrate  74  is located adjacent to slots  20 T and  20 L. As shown by curve  136 , forming the antenna in this way allows for a relatively high antenna efficiency in a low frequency band such as the 2.4 GHz frequency band. 
     Curve  138  corresponds to an antenna arrangement of the type shown in  FIG. 7  but where parasitic element  108  has been omitted. In this arrangement, slot  20 L is provided with a relatively narrow width  98 , thereby optimizing the aesthetic appearance of device  10  and minimizing the risk of a foreign object becoming lodged in slot  20 L. As shown by curve  138 , forming the antenna in this way reduces the antenna efficiency in the 2.4 GHz band to a relatively low level (e.g., an unsatisfactory level that is less than a predetermined threshold value). This antenna efficiency may be insufficient for conveying wireless data over the 2.4 GHz frequency band without generating an undesirable number of errors in the wireless data, for example. 
     Curve  140  corresponds to an antenna arrangement of the type shown in  FIG. 7  (e.g., including parasitic element  108 ). In this arrangement, lower slot  20 L is provided with a relatively narrow width  98 , thereby optimizing the aesthetic appearance of device  10  and minimizing the risk of a foreign object becoming lodged in lower slot  20 L. Parasitic element  108  may serve to redirect radio-frequency electromagnetic energy in the 2.4 GHz band from the region adjacent to lower slot  20 L towards and through upper slot  20 T ( FIG. 7 ). As shown by arrow  142  of  FIG. 10 , forming the antenna in this way boosts the antenna efficiency in the 2.4 GHz band to a satisfactory level while upper housing  12 A is in the open position. Curve  140  may have a peak magnitude that is equal to or within an acceptable margin of curve  136 . 
     The example of  FIG. 10  only shows antenna performance in the 2.4 GHz frequency band for the sake of clarity. Curves  138 ,  140 , and  136  may extend into the 5.0 GHz frequency band. In practice, curves  138 ,  140 , and  136  may exhibit satisfactory antenna efficiency in the 5.0 GHz frequency band. The examples of  FIGS. 9 and 10  are merely illustrative. In practice, curves  130 ,  132 , and  134  of  FIG. 9  and curves  138 ,  140 , and  136  of  FIG. 10  may have different shapes (e.g., curve  134  of  FIG. 9  and curve  140  of  FIG. 10  may extend across any desired frequencies). Antenna  40  may exhibit any desired number of response peaks in any desired frequency bands. The 2.4 GHz frequency band may include any desired WLAN and/or WPAN frequency bands at frequencies between 2.4 GHz and 2.5 GHz, for example. The 5.0 GHz frequency band may include any desired WLAN frequency bands at frequencies between 4.9 GHz and 5.9 GHz, for example. 
     In this way, antenna  40  may operate with satisfactory antenna efficiency across two or more frequency bands (e.g., a low frequency band such as the 2.4 GHz frequency band and a high frequency band such as the 5.0 GHz frequency band) regardless of whether upper housing  12 A is in the open, the closed position, or an intermediate position between the open and closed positions. At the same time, the width of lower slot  20 L may be sufficiently narrow so as to optimize the aesthetic appearance of device  10  and to minimize the risk of foreign objects becoming lodged or pinched within lower slot  20 L, for example. 
       FIG. 11  is a cross-sectional side view of structures that may be used in mounting antenna  40  between conductive walls  12 B- 1  and  12 B- 2  of lower housing  12 B (e.g., as viewed in the same direction as  FIGS. 6 and 7  and from the direction of arrow  89  of  FIG. 5 ). As shown in  FIG. 11 , substrate  74  may include a cavity  144 . For example, substrate  74  may have an “L-shape” with a horizontal portion  148  extending from an end of vertical portion  150 . Ventilation port openings  76  may extend through vertical portion  150  (e.g., from front surface  82  to inner surface  146  of substrate  74 ). 
     Radio-frequency transmission line  50  (e.g., a coaxial cable or other transmission line) may extend into the cavity  144  defined by substrate  74 . Conductive structures  105  of  FIGS. 6 and 7  may be formed using conductive gasket  160 , sheet metal member  152 , and conductive gasket  158 . Sheet metal member  152  may be folded around substrate  74  and cavity  144  (e.g., the edges of cavity  144  may be defined by sheet metal member  152  and substrate  74 ). For example, sheet metal member  152  may have a first end  154  interposed between horizontal portion  148  of substrate  74  and conductive upper wall  12 B- 1 . Sheet metal member  152  may have a second end  156  extending between substrate  74  and conductive lower wall  12 B- 2 . Second end  156  of sheet metal member  152  may extend across the length of cavity  144  and may, if desired, extend under vertical portion  150  of substrate  74 . 
     End  154  of sheet metal member  152  may be coupled to conductive traces  163  on top surface  90  of substrate  74  using welds or solder  162 . End  154  of sheet metal member  152  may be coupled to conductive upper wall  12 B- 1  by one or more conductive gaskets  160 . Conductive gasket  160  may be used in forming conductive structures  112  and part of conductive structures  105  of  FIGS. 6 and 7 , for example. Conductive gasket  160  may bias substrate  74  downwards towards conductive lower wall  12 B- 2  to help hold substrate  74  in place and/or may be adhesive. Coupling sheet metal member  152  to traces  163  may serve to mechanically secure or affix substrate  74  in place, for example. 
     End  156  of sheet metal member  152  may be coupled to conductive lower wall  12 B- 2  using one or more conductive gaskets  158 . Conductive gasket  158  may be used in forming conductive structures  110  and part of conductive structures  105  of  FIGS. 6 and 7 , for example. Conductive gasket  158  may bias substrate  74  upwards towards conductive upper wall  12 B- 1  to help hold substrate  74  in place and/or may be adhesive. 
     Ground conductor  54  of transmission line  50  may be coupled to sheet metal member  152  at ground antenna feed terminal  46 . If desired, ground conductor  54  may be coupled to sheet metal member  152  at other locations such as locations  164  (e.g., using solder or welds). In the example of  FIG. 11 , antenna resonating element arm  60  is formed from conductive traces on inner surface  146  of substrate  74 . Signal conductor  52  of transmission line  50  may be coupled to positive antenna feed terminal  44  on antenna resonating element arm  60 . Antenna resonating element arm  60  may be coupled to sheet metal member  152  over return path  62 . In another suitable arrangement, antenna resonating element arm  60  may be formed on front surface  82  of substrate  74 . In this scenario, return path  62  and/or signal conductor  52  may include conductive vias extending through vertical portion  150  of substrate  74  or may extend through openings in vertical portion  150  of substrate  74 . Antenna resonating element arm  60  may be located at cavity depth  116  from sheet metal member  152 . Forming antenna resonating element arm  60  on inner surface  146  may protect the antenna resonating element arm from damage or contaminants, for example. 
     When configured in this way, conductive upper wall  12 B- 1 , conductive lower wall  12 B- 2 , conductive gasket  160 , conductive gasket  158 , sheet metal member  152 , and/or conductive traces  163  may define the conductive cavity backing the antenna resonating element of antenna  40  while also serving to secure the antenna resonating element in place within lower housing  12 B. The example of  FIG. 11  is merely illustrative. In general, substrate  74  and sheet metal member  152  may have any desired shape. Any desired conductive components may be used in forming the conductive cavity for antenna  40 . 
     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: 20180515
Publication Date: 20200728
Grant Date: 20200728
Priority Date: 20180515
Inventors: Barrera, Joel D.
GUTERMAN, Jerzy S.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/1221", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/378", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/106", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/392", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/392", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/371", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/106", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q3/24", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q13/106", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/392", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 68533065