PATENT DOCUMENT

Publication Number: US-9496600-B2
Application Number: US-201314053104-A
Country: US
Kind Code: B2

Title: Electronic device with array of antennas in housing cavity

Abstract:
Metal housing walls may form an antenna cavity. Antenna structures may be formed from metal traces mounted on a carrier in the antenna cavity. The antenna structures may form an array of antennas such as an array of planar inverted-F antennas. The housing may have an inner cavity wall such as a circular inner cavity wall. The planar inverted-F antennas may lie between the inner cavity wall and the metal walls of the housing. Each planar inverted-F antenna may have an associated parasitic antenna resonating element. The planar inverted-F antennas may be configured to resonate in upper and lower frequency bands. The parasitic elements may each extend inwardly from the metal walls and may broaden the frequency response of the planar inverted-F antennas in the lower frequency band. Parasitic elements may be used to isolate antennas from each other.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a cylindrical metal housing forming an antenna cavity; 
 antenna resonating element structures in the antenna cavity, wherein the antenna resonating element structures and the antenna cavity form an array of antennas in the cylindrical metal housing, the array of antennas comprise first, second, and third antennas, and the first, second and third antennas comprise planar inverted-F antennas; and 
 an inner cavity wall that lies within the cylindrical metal housing, wherein the first antenna lies between the inner cavity wall and the cylindrical metal housing, the second antenna lies between the inner cavity wall and the cylindrical metal housing, and the third antenna lies between the inner cavity wall and the cylindrical metal housing. 
 
     
     
       2. The electronic device defined in  claim 1  wherein each of the planar inverted-F antennas comprises a respective metal trace with a cut-out region adjacent to the cylindrical metal housing. 
     
     
       3. The electronic device defined in  claim 1  wherein the first, second, and third antennas are separated from each other by 120°. 
     
     
       4. The electronic device defined in  claim 1  wherein the antenna resonating element structures comprise metal traces on a dielectric carrier. 
     
     
       5. The electronic device defined in  claim 4  wherein the dielectric carrier comprises a plastic carrier with a horseshoe shape. 
     
     
       6. The electronic device defined in  claim 1  further comprising:
 radio-frequency transceiver circuitry; and 
 cables that couple the radio-frequency transceiver circuitry to the first, second, and third antennas. 
 
     
     
       7. The electronic device defined in  claim 1  wherein the first, second, and third antennas each have a different respective polarization orientation.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to 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, wireless communications are handled using multiple antennas. If care is not taken, the presence of one antenna can adversely affect the performance of another antenna. The presence of conductive device structures such as housing walls can also give rise to antenna cavity modes that impact performance. 
     It would therefore be desirable to be able to provide improved antennas for use in an electronic device. 
     SUMMARY 
     An electronic device may be provided with a housing formed from metal housing walls. The metal housing walls may form an antenna cavity. For example, the metal housing walls may include a metal floor and metal sidewalls that extend upwards from the floor to form a cylindrical housing with a circular opening. 
     Antenna structures may be formed from metal traces mounted on a carrier in the antenna cavity. The carrier may have a circular shape that is received within a circular outer metal housing wall in the housing. 
     The antenna structures may form an array of antennas such as an array of planar inverted-F antennas. The housing may have an inner cavity wall such as a circular inner cavity wall. The planar inverted-F antennas may lie between the inner cavity wall and the metal walls of the housing. 
     Each planar inverted-F antenna may have an associated parasitic antenna resonating element. The planar inverted-F antennas may be configured to resonate in upper and lower frequency bands. The parasitic elements may each extend inwardly from the metal walls and may broaden the frequency response of the planar inverted-F antennas in the lower frequency band. 
     The planar inverted-F antennas may include first, second, and third antennas that are arranged in a circular array and are separated from each other by 120°. Parasitic elements may be formed between the planar inverted-F antennas to isolate adjacent antennas in the array from each other. Each antenna in the array may have a different respective polarization orientation to minimize antenna coupling. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of an illustrative electronic device in accordance with an embodiment. 
         FIG. 3  is a cross-sectional side view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 4  is a cross-sectional top view of an illustrative device housing with a triangular footprint in accordance with an embodiment. 
         FIG. 5  is a cross-sectional top view of an illustrative device housing with a rectangular footprint in accordance with an embodiment. 
         FIG. 6  is a cross-sectional top view of an illustrative device housing with a circular footprint in accordance with an embodiment. 
         FIGS. 7, 8, and 9  are cross-sectional top views of an illustrative electronic device having housing walls that form a rectangular cavity showing cavity modes that are supported by the cavity in accordance with an embodiment. 
         FIGS. 10 and 11  are cross-sectional top views of an illustrative electronic device having housing walls that form a circular cavity showing cavity modes that are supported by the cavity in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side of view of an illustrative electronic device having housing walls with a lip that supports cavity modes in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative electronic device showing how placement of antennas within a cavity formed from housing walls influences antenna performance in accordance with an embodiment. 
         FIG. 14  is a top view of a pair of antennas with diverse polarizations in a housing that forms a circular antenna cavity in accordance with an embodiment. 
         FIG. 15  is a top view of three antennas with three respective different polarization orientations in a housing that forms a circular antenna cavity in accordance with an embodiment. 
         FIG. 16  is a diagram of an illustrative inverted-F antenna in accordance with an embodiment. 
         FIG. 17  is a cross-sectional side view of a planar inverted-F antenna that is adjacent to a housing wall and that is fed using a feed on the inner side of the antenna in accordance with an embodiment. 
         FIG. 18  is a top view of the antenna of  FIG. 17  in accordance with an embodiment. 
         FIG. 19  is a cross-sectional side view of a planar inverted-F antenna that is adjacent to a housing wall and that is fed using a feed on the outer side of the antenna in accordance with an embodiment. 
         FIG. 20  is a top view of the antenna of  FIG. 19  in accordance with an embodiment. 
         FIG. 21  is a cross-sectional side view of a planar inverted-F antenna that located between a housing wall and an inner side wall structure and that is fed using a feed on the outer side of the antenna in accordance with an embodiment. 
         FIG. 22  is a top view of the antenna of  FIG. 21  in accordance with an embodiment. 
         FIG. 23  is a perspective view of an illustrative array of antennas formed on a horseshoe-shaped plastic carrier with metal structures in accordance with an embodiment. 
         FIG. 24  is a perspective view of a ring-shaped antenna array having three antennas separated by three respective parasitic resonating elements to help isolate the antennas from each other in accordance with an embodiment. 
         FIG. 25  is a top view of an illustrative parasitic resonating element in accordance with an embodiment. 
         FIG. 26  is a top view of an illustrative dual-band planar inverted-F antenna having an associated strip-shaped parasitic resonating element in accordance with an embodiment. 
         FIG. 27  is a graph in which antenna performance (voltage standing wave ratio) for an antenna of the type shown in  FIG. 26  has been plotted as a function of operation frequency in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with antennas. There may be multiple antennas mounted in the vicinity of each other in a device. For example, an array of two or three or more antennas may be used in a device. Isolation structures may be used to help decouple the antennas from each other. In electronic devices with conductive structures such as conductive housings, it may be desirable or necessary for the antennas to operate within an antenna cavity. The cavity may be formed from ground plane structures such as metal housing walls, traces on plastic carriers, internal metal device structures, and other conductive structures. The antennas may be located within the cavity while exhibiting satisfactory antenna performance and isolation. 
     An illustrative electronic device that may be provided with antennas is shown in  FIG. 1 . Electronic device  10  of  FIG. 1  may have a cylindrical shape formed from a cylindrical housing  12 . Housing  12  may be formed from plastic, fiber-composite materials, glass, ceramic, metal, other materials, or combinations of these materials. As an example, housing  12  may be formed from a metal such as aluminum or stainless steel. The cylindrical inner volume of device  10  may form a cavity such as cavity  14 . Antennas in device  10  may be formed form antenna resonating element structures located within cavity  14 . 
     In the  FIG. 1  example, housing  12  has a cylindrical shape. Housing  12  may, if desired, have other shapes (e.g., rectangular box shapes, pyramidal shapes, shapes with curved edges, shapes with straight edges, shapes with combinations of planar and curved surfaces, etc.). The example of  FIG. 1  is merely illustrative. 
     Electronic device  10  may be a computing device such as a computer (e.g., a laptop or desktop computer), a computer monitor containing an embedded computer, a tablet computer, a router, a modem, a wireless access point, a set-top box, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. As an example, electronic device  10  may be a desktop computer that is coupled to an external monitor using a cable and/or wireless signaling schemes. 
     A schematic diagram of device  10  is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include control circuitry  20 . Control circuitry  20  may include storage and processing circuitry for controlling the operation of device  10 . Control circuitry  20  may, for example, include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Control circuitry  20  may include processing circuitry based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio codec chips, application specific integrated circuits, etc. 
     Control circuitry  20  may be used to run software on device  10 , such as operating system software and application software. Using this software, control circuitry  20  may, for example, transmit and receive wireless data, tune antennas to cover communications bands of interest, and perform other functions related to the operation of device  10 . 
     Input-output devices  22  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output circuitry  22  may include communications circuitry such as wired communications circuitry. Device  10  may also use wireless circuitry such as transceiver circuitry  24  and antenna structures  26  to communicate over one or more wireless communications bands. 
     Input-output devices  22  may include input-output components with which a user can control the operation of device  10 . A user may, for example, supply commands through input-output devices  22  and may receive status information and other output from device  10  using the output resources of input-output devices  22 . 
     Input-output devices  22  may include sensors and status indicators such as an ambient light sensor, a proximity sensor, a temperature sensor, a pressure sensor, a magnetic sensor, an accelerometer, and light-emitting diodes and other components for gathering information about the environment in which device  10  is operating and providing information to a user of device  10  about the status of device  10 . Audio components in devices  22  may include speakers and tone generators for presenting sound to a user of device  10  and microphones for gathering user audio input. Devices  22  may include one or more displays. Displays may be used to present images for a user such as text, video, and still images. Sensors in devices  22  may include a touch sensor array that is formed as one of the layers in a display. During operation, user input may be gathered using buttons and other input-output components in devices  22  such as buttons, joysticks, click wheels, scrolling wheels, touch sensors such as a touch sensor array in a touch screen display or a touch pad, key pads, keyboards, vibrators, cameras, and other input-output components. 
     Wireless communications circuitry  28  may include radio-frequency (RF) transceiver circuitry such as transceiver circuitry  24  that is formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas such as antenna structures  26 , and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  28  may include radio-frequency transceiver circuits for handling multiple radio-frequency communications bands. For example, circuitry  28  may include transceiver circuitry  24  for handling cellular telephone communications, wireless local area network signals, and satellite navigation system signals such as signals at 1575 MHz from satellites associated with the Global Positioning System. Transceiver circuitry  24  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications or other wireless local area network communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  24  may use cellular telephone transceiver circuitry for handling wireless communications in cellular telephone bands such as the bands in the range of 700 MHz to 2.7 GHz (as examples). 
     Wireless communications circuitry  28  may include antenna structures  26 . Antenna structures  26  may include one or more antennas. Antenna structures  26  may include inverted-F antennas, planar inverted-F antennas, patch antennas, loop antennas, monopoles, dipoles, single-band antennas, dual-band antennas, antennas that cover more than two bands, or other suitable antennas. Configurations in which at least one antenna in device  10  is formed from a planar inverted-F antenna structure such as a dual band planar inverted-F antenna are sometimes described herein as an example. Configurations in which multiple antennas are provided to form an array of antennas and configurations in which antennas are formed within conductive cavities are also sometimes described herein as an example. 
     To provide antenna structures  26  with the ability to cover communications frequencies of interest, antenna structures  26  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna structures  26  may be provided with adjustable circuits to tune antennas over communications bands of interest. 
     Transceiver circuitry  24  may be coupled to antenna structures  26  by signal paths such as signal path  30 . Signal path  30  may include one or more transmission lines. As an example, signal path  30  of  FIG. 2  may be a transmission line having a positive signal conductor such as line  32  and a ground signal conductor such as line  34 . Lines  32  and  34  may form parts of a coaxial cable or a microstrip transmission line (as examples). A matching network formed from components such as inductors, resistors, and capacitors may be used in matching the impedance of antenna structures  26  to the impedance of transmission line  30 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna structures  26 . 
     Transmission line  30  may be coupled to antenna feed structures associated with antenna structures  26 . As an example, antenna structures  26  may form an inverted-F antenna (e.g., a planar inverted-F antenna) or other antenna having an antenna feed with a positive antenna feed terminal such as terminal  36  and a ground antenna feed terminal such as ground antenna feed terminal  38 . Positive transmission line conductor  32  may be coupled to positive antenna feed terminal  36  and ground transmission line conductor  34  may be coupled to ground antenna feed terminal  38 . Other types of antenna feed arrangements may be used if desired. The illustrative feeding configuration of  FIG. 2  is merely illustrative. 
       FIG. 3  is a cross-sectional side view of device  10  in an illustrative configuration in which device  10  has conductive housing sidewalls  40  that define antenna cavity  14 . Antenna structures  26  may be mounted within cavity  14  and may, if desired, be covered with an optional cosmetic cover structure such as dome structure  42 . Dome  42  may be formed from a dielectric such as plastic, glass, ceramic, or other non-conductive material and may, if desired, be used as a loading (tuning) element for antenna structures  26 . Housing sidewalls  40  (sometimes referred to as antenna cavity walls) may be formed from a metal such as aluminum, stainless steel, or other metals. A circular opening A or an opening of other suitable shape may be formed at the top of cavity  14 . Optional cavity wall portions  40 ′ may narrow the opening at the upper end of cavity  14 . Cavity floor (lower housing wall)  40 ″ may also be formed from a metal such as aluminum, stainless steel, or other metals. If desired, cavity  14  may be formed at the upper end of device  10  (i.e., internal device components may be located below cavity wall  40 ″). 
     Cavities of the type shown in  FIG. 3  may sometimes be referred to as forming deep cavity structures (i.e., in scenarios in which cavity depth D is greater than lateral inner cavity dimensions, etc.). The size and shape of cavity  14  may present challenges when configuring the antenna structures of device  10  to exhibit desired antenna performance (e.g., bandwidth, efficiency, amounts of coupling between antennas and the cavity in which the antennas are mounted, etc.), particularly when D is relatively large and when antenna structures  26  are located at or near the bottom of cavity  14  (e.g., when it is desired to place antenna structures  26  deep within cavity  14  for aesthetic reasons or to satisfy other design constraints). 
       FIG. 4  is a cross-sectional top view of housing  12  showing how housing walls  40  may have a triangular cross-sectional shape. The cross-sectional top view of housing  12  in  FIG. 5  shows how housing  12  may have sidewalls  40  with other shapes such as a rectangular (e.g., a square) shape. In the illustrative configuration of  FIG. 6 , housing  12  has housing sidewalls  40  that form a cylindrical cavity (i.e., housing walls  40  have a circular shape, so that housing  12 , walls  40 , and the opening at the top of cavity  14  are characterized by a circular footprint). 
     The shape used for cavity  14  influences which antenna cavity modes are supported. Cavity modes are associated with trapped standing wave modes that do not radiate efficiently.  FIGS. 7, 8, and 9  show illustrative antenna modes of the type that may be supported by cavity  14  in a configuration in which cavity  14  has a rectangular footprint.  FIGS. 10 and 11  show illustrative cavity modes of the type that may be supported in a cylindrical cavity (i.e., a cavity with a circular footprint).  FIG. 12  shows how the presence of lip portions  40 ′ on cavity walls  40  may give rise to vertical cavity modes. 
     There may be any suitable number of antennas within cavity  14  (i.e., antenna structures  26  may include one or more antennas in cavity  14 , two or more antennas in cavity  14 , three or more antennas in cavity  14 , or four or more antennas in cavity  14 ). The antennas may tend to couple to cavity modes of the type shown in  FIGS. 7, 8, 9, 10, 11, and 12 , when the antennas are located close to cavity walls (i.e., when distances D1 and D3 of illustrative antennas  26 A and  26 B of  FIG. 13  are small). At the same time, coupling between antennas (which should generally be minimized to maximize wireless performance in an antenna array), is increased when D1 and D3 are large and the separation D2 between antennas is smaller. To satisfy these competing concerns without making device  10  overly bulky, distances D1 and D3 are generally increased as much as possible without causing antenna coupling due to small D2 values to rise above a desired threshold amount. 
     Antenna array performance can be enhanced (i.e., antenna-to-antenna coupling can be decreased) by arranging the antennas of device  10  to exhibit polarization diversity (i.e., different polarization orientations). In the example of  FIG. 14 , a pair of antennas has been oriented so that the first antenna  26 A has a polarization that is orthogonal to the second antenna  26 B. In the example of  FIG. 15 , antennas  26 - 1 ,  26 - 2 , and  26 - 3  have been arranged to exhibit 120° angular separations with respect to each other within a cylindrical cavity  14  while orienting the polarization of each antenna towards center point  44  to ensure satisfactory polarization diversity (i.e., to ensure that each antenna&#39;s polarization orientation is different). 
     Antennas in device  10  may, if desired, be inverted-F antennas (e.g., planar inverted-F antennas). An illustrative inverted-F antenna is shown in  FIG. 16 . Antenna  26  of  FIG. 16  has antenna ground  46  and antenna resonating element  48 . In device  10 , antenna ground  46  may be formed form the antenna cavity that is formed from housing wall  40 . 
     The antenna feed for antenna  26  includes positive feed terminal  36  and ground antenna feed terminal  38  in feed branch  52 . Return path  54  couples main resonating element arm  50  to ground  46  in parallel with feed branch  52 . Main resonating element arm  50  may, if desired, have long and short branches to help antenna  26  cover multiple frequency bands of interest (e.g., a high band at a high-band frequency of 5 GHz, a low band at a low-band frequency of 2.4 GHz, etc.). In a planar inverted-F antenna configuration, arm  50  of resonating element  48  may be formed from a planar metal structure (i.e., a planar metal element extending into the page in the orientation of  FIG. 16 ). 
       FIG. 17  is a cross-sectional side view of an illustrative antenna in a cavity in device  10 . As shown in  FIG. 17 , antenna  26  includes antenna resonating element  48 . Antenna resonating element  48  may be formed from metal traces on a dielectric carrier such as carrier  56  (e.g., planar metal traces that lie in a plane parallel to the X-Y plane of  FIG. 17  mounted on a plastic carrier). Antenna  26  may have an antenna feed formed from feed terminals  36  and  38 . In the configuration of  FIG. 17 , the antenna feed is formed on the inner side of antenna  26  (i.e., the edge of resonating element  48  that is positioned close to the center of cavity  14  and that is farther from adjacent cavity sidewall  40 ). Illustrative electromagnetic field lines  58  of  FIG. 17  and the associated top view of antenna  26  shown in  FIG. 18  show how at an operating frequency such as 2.4 GHz, resonant currents may flow close to cavity wall  40  and may cause antenna  26  to capacitively couple to cavity wall  40 , tending to decrease antenna bandwidth and efficiency. 
       FIGS. 19 and 20  illustrate an alternative configuration for antenna  26  in which the feed is formed on the outer side of antenna  26  (i.e., the edge of resonating element  48  that is positioned farthest from the center of cavity  14  and closer to adjacent cavity sidewall  40 ). As shown by illustrative electromagnetic field lines  58  of  FIGS. 19 and 20 , this type of configuration may produce lower amounts of coupling between antenna  26  and the cavity (i.e., less cavity mode excitation will be exhibited), which tends to increase antenna bandwidth and efficiency. 
     Yet another illustrative antenna configuration is shown in  FIGS. 21 and 22 . In this configuration, inner cavity wall  40 ′ has been formed adjacent to the inner edge of antenna resonating element  48 . Inner cavity wall  40 ′ may have a circular shape that is nested within circular housing wall  40 . Return path  54  and the antenna feed may be formed on the opposing outer edge of antenna resonating element  48 , adjacent to cavity wall  40 . Cut-out portion  64  may be removed from resonating element  48  (i.e., area  64  may be free of metal). As shown by electromagnetic field line  58  in  FIG. 22 , this configuration may force more of the antenna currents (e.g., currents flowing when operating antenna  26  at an operating frequency such as 2.4 GHz) away from cavity wall  40  and may cause more of the electromagnetic fields  58  to be directed away from cavity wall  40 . Rather than being coupled to cavity modes, the fields produced by antenna  26  of  FIGS. 21 and 22  may tend to be coupled to radiative modes (e.g., modes that allow radio-frequency antenna signals to pass through the opening at the top of cavity  14 ), thereby enhancing antenna efficiency. 
     Inner edge  48 ′ of antenna resonating element  48  may be separated from inner cavity wall structure  40 ′″ by distance G. Decreases in the magnitude of G may increase capacitive loading and may help reduce antenna size. Reductions in antenna size, in turn, may help reduce coupling between the individual antennas in an antenna array. Excessive reductions in gap G are preferably avoided to prevent overly large reductions in bandwidth. 
     The presence of cut-out portion  64  of antenna resonating element  48  in region  62  (i.e., the absence of metal in region  64 ) and the presence of protrusion  66  of antenna resonating element  48  in region  60  may give rise to high band antenna resonances (e.g., resonances at 5 GHz), thereby allowing antenna  26  to function as a dual band antenna (i.e., a 2.4 GHz and 5 GHz antenna). 
       FIG. 23  shows how an array of antennas of the type shown in  FIGS. 21 and 22  may be formed from patterned metal traces on a dielectric carrier. The dielectric carrier may be a horseshoe shaped plastic carrier such as carrier  80  having opposing ends separated by gap  70 . Carrier  80  may form a carrier such as the illustrative carrier  56  of  FIG. 21 . Antennas  26 - 1 ,  26 - 2 , and  26 - 3  may be arranged on carrier  80  as described in  FIG. 15  to exhibit polarization diversity and minimized coupling. 
     The antenna array of  FIG. 23  may be mounted within a metal cylindrical housing in which the antenna array has an outer housing sidewall  40  and an inner wall structure  40 ′″ (e.g., a concentric inner wall structure). Metal traces may be used to form antenna resonating element  48 - 1  for antenna  26 - 1 , antenna resonating element  48 - 2  for antenna  26 - 2 , and antenna resonating element  48 - 3  for antenna  26 - 3 . Metal traces on the horseshoe-shaped plastic carrier may also be used to form outer trace  72  and inner trace  74 . Outer trace  72  may be a vertically extending circular metal trace on the outer edge of the horseshoe-shaped carrier that lies along the inner surface of a mating cylindrical housing sidewall  40  when the antenna structures of  FIG. 23  are mounted in cavity  14 . Inner trace  74  may form some or part of inner wall  40 ′ (see, e.g., inner wall  40 ′ of  FIGS. 21 and 22 ) Inner trace  74  may be a vertically extending wall that is circular in shape and concentric with circular outer trace  72 . 
     Transceiver circuitry  24  (e.g., a printed circuit board such as a radio card) may be located in gap  70 . Cables (e.g., coaxial cables) or other transmission lines such as transmission lines  30 - 1 ,  30 - 2 , and  30 - 3  may be used to route signals between transceiver circuitry  24  and antennas  26 - 1 ,  26 - 2 , and  26 - 3 . Solder or other conductive structures may be used in attaching transmission lines to the metal structures of the antennas. Recesses  76  may be formed in carrier  80  to accommodate screws  78  or other functional portions of device  10 . Protrusions  73  such as tabs with screw holes or other mounting structures may be incorporated into carrier  80  to facilitate mounting within housing  12 . If desired, some of the antennas in the antenna array of  FIG. 23  may be implemented using mirrored (flipped) configurations (see, e.g., resonating element  48 - 3  which is mirrored with respect to resonating elements  48 - 1  and  48 - 2 ). Donut-shaped carriers (e.g., a ring without gaps such as gap  70 ) and other types of carriers may be used in mounting antenna structures in cavity  14 . The use of horseshoe shaped carrier  80  of  FIG. 23  having a circular ring shape that is received within the circular interior of a cylindrical housing is merely illustrative. 
     If desired, isolation between respective antennas may be enhanced by incorporating one or more parasitic antenna resonating elements into the antenna array. As shown in  FIG. 24 , for example, parasitic antenna resonating element  82 - 1  may be located between antenna  26 - 3  and antenna  26 - 1  to help electromagnetically isolate antennas  26 - 3  and  26 - 1  from each other, parasitic antenna resonating element  82 - 2  may be located between antenna  26 - 1  and antenna  26 - 2  to help electromagnetically isolate antennas  26 - 1  and  26 - 2  from each other, and parasitic antenna resonating element  82 - 3  may be located between antenna  26 - 2  and antenna  26 - 3  to help electromagnetically isolate antennas  26 - 2  and  26 - 3  from each other (i.e., antennas and parasitic elements may be arranged in a circle in an alternating pattern). An illustrative T-shaped parasitic antenna resonating element trace (trace  82 ) that may be used in forming each parasitic resonating element of  FIG. 24  is shown in  FIG. 25 . Parasitic antenna resonating element  82  of  FIG. 25  may have a long arm for resonating at 2.4 GHz (and therefore helping to isolate antennas operating at 2.4 GHz) and may have a short arm for resonating at 5 GHz (and therefore helping to isolate antennas operating at 5 GHz). Isolation may also be provided at other frequencies. The use of a parasitic antenna resonating element that provides isolation at 2.4 GHz and 5 GHz is merely illustrative. 
       FIG. 26  shows how a parasitic antenna resonating element may be added to each antenna  26  in the antenna array to help configure the frequency response of antenna  26 . Resonating element  84  may, as an example, be formed from a strip-shaped metal trace (i.e., a metal strip) that extends outwards from housing wall  40  adjacent to resonating element  48  of antenna  26 . The height H of resonating element  84  may be adjusted to configure the frequency response of parasitic antenna resonating element  84  and therefore antenna  26  of  FIG. 26 . 
       FIG. 27  is a graph in which antenna performance (voltage standing wave ratio) has been plotted as a function of operating frequency f. As shown in  FIG. 27 , antenna  26  may be a dual band antenna that exhibits a first resonance in a low communications band (e.g., a frequency band at 2.4 GHz, as illustrated by resonance  90 ) and that exhibits a second resonance in a high communications band (e.g., a frequency band at 5 GHz, as illustrated by resonance  92 ). Peak  94  may be associated with parasitic resonating element  84 . By increasing H, the resonance associated with parasitic resonating element  84  may be moved from the position of peak  94  in  FIG. 27  to the position of peak  94 ′ in  FIG. 27 , merging with the low band resonance of resonating element  48  and effectively broadening the low band resonance for antenna  26 . 
     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: 20131014
Publication Date: 20161115
Grant Date: 20161115
Priority Date: 20131014
Inventors: IRCI ERDINC
GUTERMAN JERZY
HAYLOCK JONATHAN
PASCOLINI MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/24", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/42", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/24", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 52809229