PATENT DOCUMENT

Publication Number: US-9287627-B2
Application Number: US-201113223102-A
Country: US
Kind Code: B2

Title: Customizable antenna feed structure

Abstract:
Custom antenna structures may be used to compensate for manufacturing variations in electronic device antennas. An antenna may have an antenna feed and conductive structures such as portions of a peripheral conductive electronic device housing member. The custom antenna structures compensate for manufacturing variations that could potentially lead to undesired variations in antenna performance. The custom antenna structures may make customized alterations to antenna feed structures or conductive paths within an antenna. An antenna may be formed from a conductive housing member that surrounds an electronic device. The custom antenna structures may be formed from a printed circuit board with a customizable trace. The customizable trace may have a contact pad portion on the printed circuit board. The customizable trace may be customized to connect the pad to a desired one of a plurality of contacts associated with the conductive housing member to form a customized antenna feed terminal.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 an antenna having a conductive antenna resonating element structure comprising a metal housing structure; 
 a conductive member that is electrically connected to the conductive antenna resonating element structure, wherein the conductive member comprises a bracket that is welded to the metal housing structure and that has at least first and second contacts at first and second locations along the metal housing structure that serve as first and second positive antenna feed terminals for the antenna; 
 custom antenna structures that compensate for manufacturing variations that affect antenna performance in the antenna, wherein the custom antenna structures include a printed circuit board with a conductive path connected to the conductive member through only a selected one of the first and second contacts, wherein the conductive path is formed on a surface of the printed circuit board and is coupled to a contact pad on the printed circuit board that connects the conductive path to the selected one of the first and second contacts, and wherein a portion of the printed circuit board overlaps the conductive member such that the surface of the printed circuit board is in direct contact with the conductive member; and 
 a screw that is received by threads in the metal bracket to hold the printed circuit board against the bracket. 
 
     
     
       2. The electronic device defined in  claim 1  further comprising:
 a radio-frequency transceiver; and 
 a transmission line that is coupled between the antenna and the radio-frequency transceiver, wherein the transmission line has a positive signal conductor, and wherein the conductive path is configured to couple the positive signal conductor to the conductive member through the selected one of the first and second contacts. 
 
     
     
       3. The electronic device defined in  claim 1  wherein the electronic device has a rectangular periphery and wherein the metal housing structure comprises a peripheral conductive housing member that runs along at least part of the rectangular periphery. 
     
     
       4. The electronic device defined in  claim 3  wherein the metal bracket is welded to the peripheral conductive housing member. 
     
     
       5. The electronic device defined in  claim 4  wherein the first and second contacts comprise metal paint on the metal bracket. 
     
     
       6. A method for fabricating wireless electronic devices, comprising:
 measuring antenna performance in a test device; 
 based on the measured antenna performance in the test device, fabricating a printed circuit board with a customized trace; and 
 manufacturing a wireless electronic device that includes an antenna having a conductive antenna resonating element structure and a conductive member that is electrically connected to the conductive antenna resonating element structure, wherein the conductive member has at least first and second contacts and wherein manufacturing the wireless electronic device comprises installing the printed circuit board within the wireless electronic device so that the customized trace overlaps and is in direct contact with the first contact without being in contact with the second contact and the second contact is in direct contact with the printed circuit board, and wherein the customized trace serves as an antenna feed terminal for the antenna. 
 
     
     
       7. The method defined in  claim 6  wherein manufacturing the wireless electronic device comprises forming the antenna at least partly from a peripheral conductive housing member that runs along at least part of a peripheral edge in the wireless electronic device. 
     
     
       8. The method defined in  claim 7  wherein the conductive member comprises a metal member and wherein manufacturing the wireless electronic device comprises welding the metal member to the peripheral conductive housing member. 
     
     
       9. An antenna, comprising:
 a conductive antenna resonating element member comprising a peripheral conductive housing member that runs along at least part of a peripheral edge of an electronic device; 
 a metal member welded to the peripheral conductive housing member, wherein the metal member has a planar surface and first and second contact regions formed on the planar surface, and wherein the first and second contact regions are associated with respective locations for first and second positive antenna feed terminals for the antenna; and 
 a printed circuit board having an antenna feed signal trace with a contact pad that contacts the first contact region without contacting the second contact region. 
 
     
     
       10. The antenna defined in  claim 9  wherein the conductive antenna resonating element member forms at least part of an inverted-F antenna arm. 
     
     
       11. The antenna defined in  claim 9 , further comprising a screw, wherein the planar surface has threads interposed between the first and second contact regions, wherein the printed circuit board has an opening that overlaps the threads, and wherein the screw is configured to screw into the threads and hold the printed circuit board in direct contact with the bracket. 
     
     
       12. The electronic device defined in  claim 3 , wherein the peripheral conductive housing member comprises opposing interior and exterior surfaces, wherein the metal bracket comprises a first surface that is substantially parallel to the interior surface of the peripheral conductive housing member, wherein the metal bracket comprises a second surface that is substantially perpendicular to the first surface of the metal bracket, and wherein the first and second contacts are formed on the second surface of the metal bracket.

Description:
BACKGROUND 
     This relates generally to electronic devices, and more particularly, to electronic devices that have antennas. 
     Electronic devices such as computers and handheld electronic devices are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry such as cellular telephone circuitry to communicate using cellular telephone bands. Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. For example, electronic devices may communicate using the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth° band at 2.4 GHz. 
     Antenna performance can be critical to proper device operation. Antennas that are inefficient or that are not tuned properly may result in dropped calls, low data rates, and other performance issues. There are limits, however, to how accurately conventional antenna structures can be manufactured. 
     Many manufacturing variations are difficult or impossible to avoid. For example, variations may arise in the size and shape of printed circuit board traces, variations may arise in the density and dielectric constant associated with printed circuit board substrates and plastic parts, and conductive structures such as metal housing parts and other metal pieces may be difficult or impossible to construct with completely repeatable dimensions. Some parts are too expensive to manufacture with precise tolerances and other parts may need to be obtained from multiple vendors, each of which may use a different manufacturing process to produce its parts. 
     Manufacturing variations such as these may result in undesirable variations in antenna performance. An antenna may, for example, exhibit an antenna resonance peak at a first frequency when assembled from a first set of parts, while exhibiting an antenna resonance peak at a second frequency when assembled from a second set of parts. If the resonance frequency of an antenna is significantly different than the desired resonance frequency for the antenna, a device may need to be scrapped or reworked. 
     It would therefore be desirable to provide a way in which to address manufacturability issues such as these so as to make antenna designs more amenable to reliable mass production. 
     SUMMARY 
     An electronic device may be provided with antennas. An electronic device may have a peripheral conductive housing member that runs along a peripheral edge of the electronic device. The peripheral conductive housing member and other conductive structures may be used in forming an antenna in the electronic device. An antenna feed having positive and ground antenna feed terminals may be used to feed the antenna. 
     During manufacturing operations, parts for an electronic device may be constructed using different manufacturing processes and may otherwise be subject to manufacturing variations. To compensate for manufacturing variations, custom antenna structures may be included in the antenna of each electronic device. The custom antenna structures may make customized alterations to antenna feed structures or other conductive antenna paths. 
     The custom antenna structures may be formed from a printed circuit board with a customizable trace. The customizable trace may form a contact pad on the printed circuit board. The customizable trace may be customized so that the pad connects to a desired one of a plurality of contacts associated with the conductive housing member to form a customized antenna feed terminal. The customized antenna feed terminal may, for example, be used to feed the peripheral conductive housing member at a selected location along its length to adjust antenna performance. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative electronic device with wireless communications circuitry in accordance with an embodiment of the present invention. 
         FIG. 3  is circuit diagram of illustrative wireless communications circuitry having a radio-frequency transceiver coupled to an antenna by a transmission line in accordance with an embodiment of the present invention. 
         FIG. 4  is a top view of a slot antenna showing how the position of antenna feed terminals may be varied to adjust antenna performance and thereby compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram of an inverted-F antenna showing how the position of antenna feed terminals may be varied to adjust antenna performance and thereby compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 6  is a top view of a slot antenna showing how the position of conductive antenna structures in the slot antenna can be varied to adjust slot size and thereby adjust antenna performance to compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram of an inverted-F antenna showing how the position of conductive antenna structures in the inverted-F antenna can be varied to adjust the size of an antenna resonating element structure and thereby adjust antenna performance to compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 8  is a diagram of antenna structures in an electronic device showing how customized antenna feed structures may be used to adjust an antenna to compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 9  is a top interior view of an illustrative electronic device of the type that may be provided with custom antenna structures to adjust antenna performance and thereby compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 10  is a top view of an a portion of an electronic device having an antenna structure that is formed from a peripheral conductive housing member and customized antenna feed structures to adjust antenna performance to compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 11  is a perspective view of an illustrative custom antenna structure based on printed circuit board that has customizable traces and based on a bracket with corresponding antenna feed contacts at different positions to adjust antenna performance to compensate for manufacturing variations in accordance with an embodiment of the present invention. 
         FIG. 12  is a flow chart of illustrative steps involved in characterizing antenna performance in electronic devices formed from a set of components and compensating for manufacturing variations by customizing antenna feed structures in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     An illustrative electronic device of the type that may be provided with custom antenna structures to compensate or manufacturing variations is shown in  FIG. 1 . Electronic devices such as illustrative electronic device  10  of  FIG. 1  may be laptop computers, tablet computers, cellular telephones, media players, other handheld and portable electronic devices, smaller devices such as wrist-watch devices, pendant devices, headphone and earpiece devices, other wearable and miniature devices, or other electronic equipment. 
     As shown in  FIG. 1 , device  10  includes housing  12 . Housing  12 , which is sometimes referred to as a case, may be formed of materials such as plastic, glass, ceramics, carbon-fiber composites and other fiber-based composites, metal, other materials, or a combination of these materials. Device  10  may be formed using a unibody construction in which most or all of housing  12  is formed from a single structural element (e.g., a piece of machined metal or a piece of molded plastic) or may be formed from multiple housing structures (e.g., outer housing structures that have been mounted to internal frame elements or other internal housing structures). 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or other touch sensors or may be touch insensitive. Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electronic ink elements, liquid crystal display (LCD) pixels, or other suitable image pixel structures. A cover layer such as a cover glass member or a transparent planar plastic member may cover the surface of display  14 . Buttons such as button  16  may pass through openings in the cover glass. Openings may also be formed in the glass or plastic display cover layer of display  14  to form a speaker port such as speaker port  18 . Openings in housing  12  may be used to form input-output ports, microphone ports, speaker ports, button openings, etc. 
     Housing  12  may include a rear housing structure such as a planar glass member, plastic structures, metal structures, fiber-composite structures, or other structures. Housing  12  may also have sidewall structures. The sidewall structures may be formed from extended portions of the rear housing structure or may be formed from one or more separate members. A bezel or other peripheral member may surround display  14 . The bezel may, for example, be formed from a conductive material. With the illustrative configuration shown in  FIG. 1 , housing  12  includes a peripheral conductive member such as peripheral conductive member  122 . Peripheral conductive member  122 , which may sometimes be referred to as a band, may have vertical sidewall structures, curved or angled sidewall structures, or other suitable shapes. Peripheral conductive member  122  may be formed from stainless steel or other metals or other conductive materials. In some configurations, peripheral conductive member  122  may have one or more dielectric-filled gaps such as gaps  202 ,  204 , and  206 . Gaps such as gaps  202 ,  204 , and  206  may be filled with plastic or other dielectric materials and may be used in dividing peripheral conductive member  122  into segments. The shapes of the segments of conductive member  122  may be chosen to form antennas with desired antenna performance characteristics. 
     Wireless communications circuitry in device  10  may be used to form remote and local wireless links. One or more antennas may be used during wireless communications. Single band and multiband antennas may be used. For example, a single band antenna may be used to handle local area network communications at 2.4 GHz (as an example). As another example, a multiband antenna may be used to handle cellular telephone communications in multiple cellular telephone bands. Antennas may also be used to receive global positioning system (GPS) signals at 1575 MHz in addition to cellular telephone signals and/or local area network signals. Other types of communications links may also be supported using single-band and multiband antennas. 
     Antennas may be located at any suitable locations in device  10 . For example, one or more antennas may be located in an upper region such as region  22  and one or more antennas may be located in a lower region such as region  20 . If desired, antennas may be located along device edges, in the center of a rear planar housing portion, in device corners, etc. 
     Antennas in device  10  may be used to support any communications bands of interest. For example, device  10  may include antenna structures for supporting local area network communications (e.g., IEEE 802.11 communications at 2.4 GHz and 5 GHz for wireless local area networks), signals at 2.4 GHz such as Bluetooth® signals, voice and data cellular telephone communications (e.g., cellular signals in bands at frequencies such as 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, etc.), global positioning system (GPS) communications at 1575 MHz, signals at 60 GHz (e.g., for short-range links), etc. 
     A schematic diagram showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Input-output circuitry  30  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, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, motion sensors (accelerometers), capacitance sensors, proximity sensors, etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . Transceiver circuitry  36  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in cellular telephone bands at 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2100 MHz (as examples). Circuitry  38  may handle voice data and non-voice data. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, etc. Wireless communications circuitry  34  may include global positioning system (GPS) receiver equipment such as GPS receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include one or more antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structure, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. 
     As shown in  FIG. 3 , transceiver circuitry  90  may be coupled to one or more antennas such as antenna  40  using transmission line structures such as antenna transmission line  92 . Transmission line  92  may have positive signal path  92 A and ground signal path  92 B. Paths  92 A and  92 B may be formed on rigid and flexible printed circuit boards, may be formed on dielectric support structures such as plastic, glass, and ceramic members, may be formed as part of a cable, etc. Transmission line  92  may be formed using one or more microstrip transmission lines, stripline transmission lines, edge coupled microstrip transmission lines, edge coupled stripline transmission lines, coaxial cables, or other suitable transmission line structures. 
     Transmission line  92  may be coupled to an antenna feed formed from antenna feed terminals such as positive antenna feed terminal  94  and ground antenna feed terminal  96 . As shown in  FIG. 3 , changes may be made to the conductive pathways that are used in feeding antenna  40 . For example, conductive structures in device  10  may be customized to change path  92 A to a configuration of the type illustrated by path  92 A′ to couple transmission line  92  to positive antenna feed terminal  94 ′ rather than positive antenna feed terminal  94  (i.e., to adjust the location of the positive antenna feed terminal). Conductive structures may also be customized to so that path  92 B is altered to follow path  92 B′ to couple to ground antenna feed terminal  96 ′ rather than ground antenna feed terminal  96  (i.e., to adjust the location of the ground antenna feed terminal). If desired, a matching circuit or other radio-frequency front end circuitry (e.g., switches, filters, etc.) may be interposed in the radio-frequency signal path between transceiver  90 . For example, an impedance matching circuit may be interposed between transmission line  92  and antenna  40 . In this type of configuration, the changes that are made to the antenna feed may be made to the conductive structures that are interposed between the matching circuit and antenna  40  (as an example). 
     Conductive structure changes such as the illustrative changes associated with paths  92 A′ and  92 B′ of  FIG. 3  (e.g., changes to the positions of the positive and/or ground antenna feed terminals among the structures of the antenna) affect antenna performance. In particular, the frequency response of the antenna (characterized, as an example, by a standing wave ratio plot as a function of operating frequency) will exhibit changes at various operating frequencies. In some situations, the antenna will become more responsive at a given frequency and less responsive at another frequency. Feed alterations may also create global antenna efficiency increases or global antenna efficiency decreases. 
     A diagram showing illustrative feed positions that may be used in a slot antenna in device  10  is shown in  FIG. 4 . As shown in  FIG. 4 , slot antenna  40  may be formed from conductive structures  100  that form slot  98 . Slot  98  may be formed from a closed or open rectangular opening in structures  100  or may have other opening shapes. Slot  98  is generally devoid of conductive materials. In a typical arrangement, some or all of slot  98  may be filled with air and some or all of slot  98  may be filled with other dielectric materials (e.g., electronic components that are mostly formed from plastic, plastic support structures, printed circuit board substrates such as fiberglass-filled epoxy substrates, flex circuits formed from sheets of polymer such as polyimide, etc.). 
     In antennas such as slot antenna  40  of  FIG. 4 , the position of the antenna feed tends to affect antenna performance. For example, antenna  40  of  FIG. 4  will typically exhibit a different frequency response when fed using an antenna feed formed from positive antenna feed terminal  94  and ground antenna feed terminal  96  than when fed using positive antenna feed terminal  94 ′ and ground antenna feed terminal  96 ′. In this example, both the positive and ground feed terminal positions were changed simultaneously, but movement of the positive feed terminal position without adjusting the ground feed terminal (or movement of the ground terminal without adjusting the positive terminal) will generally likewise affect antenna performance. 
       FIG. 5  is a diagram showing illustrative feed positions that may be used in an inverted-F antenna in device  10 . As shown in  FIG. 5 , inverted-F antenna  40  may be formed from antenna ground  102  and antenna resonating element  108 . Antenna ground  102  and antenna resonating element  108  may be formed from one or more conductive structures in device  10  (e.g., conductive housing structures, printed circuit board traces, wires, strips of metal, etc.). Antenna resonating element  108  may have a main arm such as antenna resonating element arm  104 . Short circuit branch  106  may be used to create a short circuit path between arm  104  and ground  102 . 
     The position of the antenna feed within antenna  40  of  FIG. 5  will generally affect antenna performance. In particular, movements of the antenna feed to different positions along arm  104  will result in different antenna impedances and therefore different frequency responses for the antenna. For example, antenna  40  will typically exhibit a different frequency response when fed using antenna feed terminals  94  and  96  rather than antenna feed terminals  94 ′ and  96 ′ and will typically exhibit a different frequency response if terminal  94  is moved to the position of terminal  94 ′ without moving terminal  96  or if terminal  96  is moved to the position of terminal  96 ′ without moving terminal  94 . 
     The configuration of the conductive structures in antenna  40  such as antenna resonating element structures (e.g., the structures of antenna resonating element  108  of  FIG. 5 ) and antenna ground structures (e.g., antenna ground conductor structures  102  of  FIG. 5 ) also affects antenna performance. For example, changes to the length of antenna resonating element arm  104  of  FIG. 5 , changes to the position of short circuit branch  106  of  FIG. 5 , changes to the size and shape of ground  102  of  FIG. 5 , and changes to the slot antenna structures of  FIG. 4  will affect the frequency response of the antenna. 
       FIG. 6  illustrates how a slot antenna may be affected by the configuration of conductive elements that overlap the slot. As shown in  FIG. 6 , slot antenna  40  of  FIG. 6  has a slot opening  98  in conductive structure  100 . Two illustrative configurations are illustrated in  FIG. 6 . In the first configuration, conductive element  110  bridges the end of slot  98 . In the second configuration, conductive element  112  bridges the end of slot  98 . 
     The length of the perimeter of opening  98  affects the position of the resonance peaks of antenna  100  (e.g., there is typically a resonance peak when radio-frequency signals have a wavelength equal to the length of the perimeter). When element  112  is present in slot  98 , the size of the slot is somewhat truncated and exhibits long perimeter PL. When element  110  is present across slot  98 , the size of the slot is further truncated and exhibits short perimeter PS. Because PS is shorter than PL, antenna  40  will tend to exhibit a resonance with a higher frequency when structure  110  is present than when structure  112  is present. 
     The size and shape of the conductive structures in other types of antennas such as inverted-F antenna  30  of  FIG. 7  affect the performance of those antennas. As shown in  FIG. 7 , antenna resonating element arm  104  in antenna resonating element  108  of antenna  40  may be have a conductive structure that can be placed in the position of conductive structure  110  or the position of conductive structure  112 . The position of this conductive structure alters the effective length of antenna resonating element arm  104  and thereby alters the position of the antenna&#39;s resonant peaks. 
     As the examples of  FIGS. 3-7  demonstrate, alterations to the positions of antenna feed terminals and the conductive structures that form other portions of an antenna change the performance (e.g., the frequency response) of the antenna. Due to manufacturing variations, antenna feed positions and conductive antenna material shapes and sizes may be inadvertently altered, leading to variations in an antenna&#39;s frequency response relative to a desired nominal frequency response. These unavoidable manufacturing variations may arise due to the limits of manufacturing tolerances (e.g., the limited ability to machine metal parts within certain tolerances, the limited ability to manufacture printed circuit board traces with desired conductivities and line widths, trace thickness, etc.). To compensate for undesired manufacturing variations such as these, device  10  may include custom antenna structures. 
     In a typical manufacturing process, different batches of electronic device  10  (e.g., batches of device  10  formed form parts from different vendors or parts made from different manufacturing processes) can be individually characterized. Once the antenna performance for a given batch of devices has been ascertained, any needed compensating adjustments can be made by forming customized antenna structures such as customized conductive structures associated with an antenna feed and installing the customized antenna structures within the antenna portion of each device. 
     As an example, a first custom structure may be formed with a first layout to ensure that the performance of a first batch of electronic devices is performing as expected, whereas a second custom structure may be provided with a second layout to ensure that the performance of a second batch of electronic devices is performing as expected. With this type of arrangement, the antenna performances for the first and second batches of devices can be adjusted during manufacturing by virtue of inclusion of the custom structures, so that identical or nearly identical performance between the first and second batches of devices is obtained. 
       FIG. 8  shows how antenna  40  may include conductive structures such as conductive structures  114  and custom structures such as custom structures  116 . Conductive structures  114  may be antenna resonating element structures, antenna ground structures, etc. With one suitable arrangement, conductive structures  114  may be conductive housing structures (e.g., conductive portions of housing  12  such as peripheral conductive housing member  122  of  FIG. 1 ). Custom structures  116  may be interposed between transmission line  92  and conductive structures  114 . Transceiver circuitry  90  may be coupled to transmission line  92 . 
     As shown in  FIG. 8 , custom structures  116  may include signal paths such as signal path  118 . Signal path  118  may include positive and ground structures (e.g., to form transmission structures) or may contain only a single signal line (e.g., to couple part of a transmission line to an antenna structure, to couple respective antenna structures together such as two parts of an antenna resonating element, to connect two parts of a ground plane, etc.). If desired, radio-frequency front-end circuitry such as switching circuitry, filters, and impedance matching circuitry (not shown in  FIG. 8 ) may be coupled between transceiver  90  and conductive structures  114  and other conductive structures associated with antenna  40 . 
     Signal path  118  may be customized during manufacturing operations. For example, custom structures  116  may be manufactured so that a conductive line or other path takes the route illustrated by path  118 A of  FIG. 8  or may be manufactured so that a conductive line or other path takes the route illustrated by path  118 B of  FIG. 8 . Some electronic devices may receive custom structures  116  in which path  118  has been configured to follow route  118 A, whereas other electronic devices may receive custom structures  116  in which path  118  has been configured to follow route  118 B. By providing different electronic devices (each of which includes an antenna of the same nominal design) with appropriate customized antenna structures, performance variations can be compensated and performance across devices can be equalized. 
     The custom antenna structures may be formed from fixed (non-adjustable) structures that are amenable to mass production. Custom structures  116  may, for example, be implemented using springs, clips, wires, brackets, machined metal parts, conductive traces such as metal traces formed on dielectric substrates such as plastic members, printed circuit board substrates, layers of polymer such as polyimide flex circuit sheets, combinations of these conductive structures, conductive elastomeric materials, spring-loaded pins, screws, interlocking metal engagement structures, other conductive structures, or any combination of these structures. Custom structures  116  may be mass produced in a fixed configuration (once an appropriate configuration for custom structures  116  been determined) and the mass produced custom structures may be included in large batches of devices  10  as part of a production line manufacturing process (e.g. a process involving the manufacture of thousands or millions of units). 
     An illustrative configuration that may be used for an antenna in device  10  is shown in  FIG. 9 . As shown in  FIG. 9 , antenna  40  in region  22  of device  10  may be formed from a ground plane such as ground plane  208  and antenna resonating element  108 . Ground plane  208  may be formed from conductive structures in the interior of device  10  such as patterned sheet metal structures over which plastic structures have been molded. Ground plane  208  may also include other conductive structures such as radio-frequency shielding cans, integrated circuits, conductive ground plane structures in printed circuit board, and other electrical components. Antenna resonating element  108  may be formed from a segment of peripheral conductive housing member  122  that extends between gap  202  and gap  204  (as an example). This segment of peripheral conductive housing member  122  may serve as conductive structure  114  of  FIG. 8  and may form inverted-F antenna resonating element arm structures such as arm  104  of  FIG. 7 . Ground plane  208  may serve as ground  102  of  FIG. 7 . Dielectric-filled gap  123  may be interposed between member  122  and ground pane  208 . Gap  123  may be filled with air, plastic, and other dielectric. 
     Conductive structure  210  may form a short circuit branch for antenna  40  that extends between segment  122 B of peripheral conductive housing member  122  and ground plane  208 . An antenna feed formed from positive antenna feed terminal  94  and ground antenna feed terminal  96  may be used in feeding antenna  40 . Portion  122 A of peripheral conductive housing member  122  may form a low-band inverted-F antenna resonating element structure in resonating element  108  and portion  122 B of peripheral conductive housing member  122  may form a high-band inverted-F antenna resonating element structure in resonating element  108  (as an example). The relatively longer length LBA of portion  122 A may help portion  122 A in antenna resonating element  108  give rise to an antenna resonance peak covering one or more low antenna frequency bands, whereas the relatively shorter length HBA of portion  122 B may help portion  122 B in antenna resonating element  108  give rise to an antenna resonance peak covering one or more high antenna frequency bands. Configurations for antenna  40  that have different types of antenna resonating element (e.g., loop antenna resonating element structures, planar inverted-F structure, dipoles, monopoles, etc.) may be used if desired. The example of  FIG. 9  is merely illustrative. 
       FIG. 10  is a top view of a portion of device  10  showing how custom structures associated with the antenna feed for antenna  40  may be used to adjust the performance (e.g., the frequency response) of antenna  40 . As shown in  FIG. 10 , radio-frequency transceiver circuitry  90  may be mounted on substrate  214 . Substrate  214  may be a plastic carrier, a printed circuit formed from a flexible sheet of polymer (e.g., a flex circuit formed form a layer of polyimide with patterned conductive traces), a rigid printed circuit board (e.g., a printed circuit board formed from fiberglass-filled epoxy), or other dielectric. Transmission line  92  may be used to couple radio-frequency transceiver circuitry  90  to antenna  40 . 
     With one suitable arrangement, transmission line  92  may include a coaxial cable such as coaxial cable  92 ′ that is attached to traces on printed circuit board  214  using radio-frequency connectors  212  and  216 . Traces on printed circuit board  214  may be used to couple transceiver  90  to connector  216 . Traces on printed circuit board  214  may also be used to couple the positive and ground conductors in connector  212  to respective ground and signal traces on printed circuit board  214  adjacent to antenna  40 . The ground conductor may be coupled to ground antenna terminal  96  and ground plane  208 . The positive conductor may be coupled to peripheral conductive member  122  using custom structures  116 . 
     If desired, radio-frequency front-end circuitry  216  such as switching circuitry, radio-frequency filter circuitry, and impedance matching circuitry may be interposed between transmission line  92  and antenna  40  (e.g., between connector  212  and custom structures  116 ). 
     Custom antenna structures  116  may be formed from customizable printed circuit board traces such as optional trace  118 A, which forms a first potential signal path that can be used to couple the positive signal line in transmission line  92  to peripheral conductive member  122  in antenna resonating element  108  at positive antenna feed  94 A and optional trace  118 B, which forms a second potential signal path that can be used to couple the positive signal line in transmission line  92  to peripheral conductive member  122  in antenna resonating element  108  at positive antenna feed  94 B. 
     A conductive structure (e.g., a metal structure) such as bracket  222  may be used in coupling antenna feed terminal  94 A and antenna feed terminal  94 B to peripheral conductive member  122 . Bracket  222  may include a threaded recess that receives screw  220 . Screw  220  or other suitable fastening mechanism may be used to secure printed circuit board  214  in customized antenna structures  116  to bracket  222 . 
     As shown by dots  218 , customizable structures  116  (e.g., board  214 ) may contain additional optional paths (i.e., optional traces on board  214  that are located in positions other than the positions indicated by dashed lines  118 A and  118 B). The use of two optional paths such as paths  118 A and  118 B in  FIG. 10  is merely illustrative. 
     Following characterization of conductive antenna structures associated with antenna  40 , customization structures  116  may be formed using an appropriate pattern of conductive traces. For example, a trace may be formed to create path  118 A without forming a trace for path  118 B, a trace may be created to form path  118 B without forming a trace for path  118 A, traces may be fabricated on printed circuit board  214  for both paths  118 A and  118 B, or other patterns of custom traces may be formed on printed circuit board  214  (or other substrate). 
     As described in connection with  FIG. 8 , the pattern of conductive traces that is used in routing radio-frequency signals between transmission line  92  and antenna resonating element  108  (e.g., peripheral conductive member  122 ) and, in particular, the pattern of traces that defines the feed location for antenna  40  can affect the performance of antenna  40  (e.g., the frequency response of antenna  40 ). If, for example, customization structures  116  (e.g., traces  118 A and/or  118 B on printed circuit board  214 ) are patterned with a first pattern that includes trace  118 A but not trace  118 B, the positive antenna feed terminal for antenna  40  will be located at the position indicated by antenna feed terminal  94 A. If customization structures  116  are patterned with a second pattern that includes trace  118 B but not trace  118 A, the positive antenna feed terminal for antenna  40  will have the location indicated by feed terminal  94 B. When both traces  118 A and  118 B are present on customization structures  116 , antenna  40  may be considered to have a positive antenna feed terminal that is distributed across peripheral conductive member  122  from the position of terminal  94 A to terminal  94 B. 
       FIG. 11  is an exploded perspective view of a portion of device  10  in the vicinity of antenna feed terminals  94 A and  94 B. As shown in  FIG. 11 , bracket  222  may be attached to peripheral conductive housing member  122  using welds  224 . If desired, bracket  222  may be electrically and mechanically connected to peripheral conductive housing member  122  using screws or other fasteners, solder, conductive adhesive, or other suitable attachment mechanisms. 
     Bracket  222  be formed from metal or other conductive materials. Bracket  222  may have a first portion such as portion  22 B that extends vertically and is suitable for welding to peripheral conductive housing member  122 . Bracket  222  may also have a second portion such as horizontal portion  222 A. Horizontal portion  222 A may have contact regions (sometimes referred to as contacts, contact pads, or terminals) such as contact region  228 A and  228 B. Contacts  228 A and  222 B may be located at suitable locations along the length of peripheral conductive housing member  122  for forming antenna feed terminals  94 A and  94 B, respectively. Contacts  228 A and  228 B may be formed from portions of bracket  222 . A coating such as a metal paint coating (e.g., gold paint applied using a paint brush, silver paint, metal films deposited by electrochemical deposition or physical vapor deposition, etc.) may be used to help form low-contact-resistance contact structures for contacts  228 A and  228 B. 
     Printed circuit board  214  may be used in supporting mating contacts (sometimes referred to as contact pads, contact regions, or terminals). As shown in  FIG. 11 , for example, contact  226 A and/or contact  226 B may be formed on the underside of printed circuit board  214 . Trace  222  on printed circuit board  214  may form a positive signal line that is coupled to the positive signal conductor in transmission line  92 . Contact  226 A may be electrically connected to the tip of trace  118 A when trace  118 A is present and may be used to electrically connect path  222  to contact  228 A. Contact  226 B may be connected to the tip of trace  118 B when trace  118 B is present and may be configured to mate with contact  228 B. 
     To install customized antenna structures  116  in device  10 , screw  220  may be screwed into screw threads  230  on a portion of bracket  222 . This holds printed circuit board  214  and contact regions  226 A and  226 B against bracket  222  and mating contact regions  228 A and  228 B. In a given device, customized antenna structures  116  have a particular custom pattern of traces such as trace  118 A or trace  118 B. Depending on the configuration of customized antenna structures  116 , trace  222  will be coupled to contact  228 A via path  118 A and contact  226 A to form an antenna feed at terminal  94 A, will be coupled to contact  228 B via path  118 B and contact  226 B to form an antenna feed at terminal, or will be coupled to contacts  228 A and  228 B simultaneously (when both paths  118 A and  118 B are implemented in customized antenna structures  116 ). 
       FIG. 12  is a flow chart of illustrative steps involved in manufacturing devices that include custom antenna structures  116 . 
     At step  152 , parts for a particular design of device  10  may be manufactured and collected for assembly. Parts may be manufactured by numerous organizations, each of which may use different manufacturing processes. As a result, there may be manufacturing variations in the parts that can lead to undesirable variations in antenna performance if not corrected. 
     At step  154 , a manufacturer of device  10  may assemble the collected parts to form one or more partial or complete test versions of device  10 . A typical manufacturing line may produce thousands or millions of nominally identical units of device  10 . Production may take place in numerous batches. Batches may involve thousands of units or more that are assembled from comparable parts (i.e., parts made using identical or similar manufacturing processes). Batch-to-batch variability in antenna performance is therefore typically greater than antenna performance variability within a given batch. 
     After assembling a desired number of test devices at step  154  (e.g., one or more test devices representative of a batch of comparable devices), the test devices may be characterized at step  156 . For example, the frequency response of the antenna in each of the test devices can be measured to determine whether there are frequency response curve shifts and other variations between devices (i.e., between batches). 
     When assembling test devices at step  154 , custom antenna structures  116  or other such structures with a particular configuration (i.e., a particular configuration for path  118 ) may be used. If test results from the characterization operations of step  156  reveal that antenna performance is deviating from the desired nominal performance (i.e., if there is a frequency shift or other performance variation), appropriate custom antenna structures  116  may be installed in the test devices (i.e., structures with a different trial pattern for conductive path  118 ). As indicated by line  158 , the custom antenna structures  116  and other device structures may be assembled to produce new versions of the test devices (step  154 ) and may be tested at step  156 . If testing reveals that additional modifications are needed, different custom antenna structures  116  (e.g., structures with a different configuration for customized path  118 ) may again be identified and installed in the test device(s). Once testing at step  156  reveals that the test devices are performing satisfactorily with a given type of customized antenna structures  116 , that same type of customized antenna structures  116  (i.e., structures with an identical pattern for conductor  118 ) may be selected for incorporation into production units. 
     With this approach, structures  116  with an appropriate custom pattern for line  118  or other custom configuration for the conductive portions of structures  116  may be identified from the test characterization measurements of step  156  and structures  116  with that selected configuration may be installed in numerous production devices during the production line manufacturing operations of step  160 . In a typical scenario, once the proper customization needed for structures  116  within a given batch has been identified (i.e., once the proper customized antenna structures for compensating for manufacturing variations have been selected from a plurality of different possible customized antenna structures), all devices  10  within that batch may be manufactured using the same custom antenna structures  116 . 
     Because the custom antenna structures were selected so as to compensate for manufacturing variations, the electronic devices produced at step  160  that include the custom antenna structures will perform as expected (i.e., the antenna frequency response curves for these manufactured devices will be accurate and will be properly compensated by the customized antenna structures for manufacturing variations). As each new batch is assembled, the customization process may be repeated to identify appropriate custom structures  116  for manufacturing that batch of devices. The custom antenna structures may have fixed (non-adjustable) configurations suitable for mass production. If desired, antennas  40  may also be provided with tunable structures (e.g., structures based on field-effect transistor switches and other switches) that may be controlled in real time by storage and processing circuitry  28 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20110831
Publication Date: 20160315
Grant Date: 20160315
Priority Date: 20110831
Inventors: JARVIS DANIEL W.
PASCOLINI MATTIA
NICKEL JOSHUA G.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T29/49004", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49004", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2283", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2283", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T29/49004", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q9/145", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 47742902