PATENT DOCUMENT

Publication Number: US-9654164-B2
Application Number: US-201514685904-A
Country: US
Kind Code: B2

Title: Removable electronic device case with supplemental wireless circuitry

Abstract:
A removable case may receive an electronic device. A male connector in the case may mate with a female connector in the device. A battery in the case may supply power to the device through the male connector. The electronic device may have an antenna formed from peripheral conductive housing structures and an antenna ground. The antenna may include a slot antenna resonating element. The case may have supplemental antenna structures such as a metal patch that overlaps an end of the slot antenna resonating element to retune the slot antenna resonating element to a desired operating frequency after being detuned by dielectric loading from the case. The supplemental antenna structures may overlap antennas of other types and may include tunable circuitry that is adjusted based on information received from the electronic device.

Claims:
What is claimed is: 
     
       1. A removable electronic device case that is configured to mate with an electronic device, wherein the electronic device comprises a connector port and comprises an antenna with an antenna resonance at a desired operating frequency, the removable electronic device case comprising:
 a body that is configured to receive the electronic device and that shifts the antenna resonance away from the desired operating frequency; 
 a connector that mates with the connector port; 
 control circuitry that is configured to receive control signals from the electronic device through the connector; and 
 supplemental antenna structures that are configured to retune the antenna by shifting the antenna resonance back to the desired frequency. 
 
     
     
       2. The removable electronic device case defined in  claim 1  wherein the antenna of the electronic device includes a slot resonating element and wherein the supplemental antenna structures include a metal structure that is configured to overlap the slot when the body receives the electronic device. 
     
     
       3. The removable electronic device case defined in  claim 2  wherein the slot antenna resonating element has an end and a length and wherein the metal structure comprises a patch that is configured to overlap the end and shortens the length when the body receives the electronic device. 
     
     
       4. The removable electronic device case defined in  claim 1  wherein the supplemental antenna structures include a tunable component that is actively adjusted by the control circuitry to tune the antenna based on the control signals received by the control circuitry from the electronic device through the connector. 
     
     
       5. The removable electronic device case defined in  claim 4  wherein the tunable component comprises at least one switch. 
     
     
       6. The removable electronic device case defined in  claim 5  wherein the antenna includes a slot antenna resonating element and the switch is configured to bridge the slot antenna resonating element when the body receives the electronic device. 
     
     
       7. The removable electronic device case defined in  claim 4  wherein the supplemental antenna structures comprise a monopole parasitic antenna resonating element. 
     
     
       8. The removable electronic device case defined in  claim 7  wherein the tunable component is interposed within the monopole parasitic antenna resonating element. 
     
     
       9. The removable electronic device case defined in  claim 1  wherein the antenna comprises an inverted-F antenna and the supplemental antenna structures comprise a metal patch that is configured to overlap part of the inverted-F antenna when the body receives the electronic device. 
     
     
       10. The removable electronic device case defined in  claim 9  wherein the inverted-F antenna has a resonating element arm with a first end coupled to a ground and a second end and the metal patch is configured to overlap the second end when the body receives the electronic device. 
     
     
       11. The removable electronic device case defined in  claim 9  wherein the inverted-F antenna has a resonating element arm and a return path coupled between the resonating element arm and a ground, and the metal patch is configured to overlap the return path when the body receives the electronic device. 
     
     
       12. The removable electronic device case defined in  claim 9  wherein the inverted-F antenna has a resonating element arm and the metal patch has a portion that is configured to overlap the resonating element arm and a portion that is configured to overlap an antenna ground when the body receives the electronic device. 
     
     
       13. The removable electronic device case defined in  claim 1 , wherein the electronic device comprises a first battery and the removable electronic device case further comprises:
 a second battery that is configured to charge the first battery by conveying power to the electronic device through the connector while the electronic device mates with the electronic device case. 
 
     
     
       14. A removable electronic device case that is configured to mate with an electronic device that has an antenna and a connector port, comprising:
 a body that is configured to receive the electronic device; 
 a connector that is configured to mate with the connector port; and 
 supplemental antenna structures that include a tunable component that is adjusted based on signals received through the connector to tune a resonance of the antenna when the body receives the electronic device. 
 
     
     
       15. The removable electronic device case defined in  claim 14  wherein the tunable component comprises a switch. 
     
     
       16. The removable electronic device case defined in  claim 15  wherein the antenna includes a slot antenna resonating element and the switch is configured to bridge the slot antenna resonating element when the body receives the electronic device. 
     
     
       17. The removable electronic device case defined in  claim 15  wherein the electronic device includes storage and processing circuitry, the removable electronic device case further comprising:
 a battery that is configured to supply power to the electronic device through the connector when the body receives the electronic device; and 
 control circuitry that is configured to communicate with the storage and processing circuitry through the connector and to adjust the tunable component when the body receives the electronic device. 
 
     
     
       18. The removable electronic device case defined in  claim 14 , wherein the connector port comprises a female connector port and the connector comprises a male connector that mates with the female connector port while the electronic device is received by the removable electronic device case, the male connector and the female connector port each comprise at least four contacts, and the at least four contacts comprise at least one signal pin that conveys control signals and at least one power pin that conveys power. 
     
     
       19. A removable electronic device case that is configured to mate with an electronic device that includes a connector port and that has a slot antenna resonating element with an end, the removable electronic device case comprising:
 a body that is configured to receive the electronic device; 
 a metal patch that is configured to overlap the end of the slot antenna resonating element and shorten a perimeter of the slot antenna resonating element to tune a resonance of the slot antenna resonating element to a desired frequency when the body receives the electronic device; and 
 a connector that is configured to mate with the connector port. 
 
     
     
       20. The removable electronic device case defined in  claim 19  further comprising:
 a battery that is configured to supply power to the electronic device through the connector when the body receives the electronic device, wherein the body comprises dielectric that lowers a resonant frequency for the slot antenna resonating element below a desired resonant frequency of operation, and the metal patch is located at a position within the body that overlaps the end of the slot antenna resonating element sufficiently to raise the lowered resonant frequency to the desired resonant frequency of operation when the body receives the electronic device. 
 
     
     
       21. The removable electronic device case defined in  claim 19 , wherein the metal patch is configured to shorten the perimeter of the slot antenna resonating element when radio-frequency signals are conveyed through the slot antenna resonating element and the metal patch is configured to not be in direct contact with the slot antenna resonating element when the removable electronic device case mates with the electronic device.

Description:
BACKGROUND 
     This relates generally to removable cases for electronic devices and, more particularly, to removable cases for wireless electronic devices. 
     Electronic devices often include wireless circuitry. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications with external equipment. 
     Removable cases are sometimes used with electronic devices. Some cases are passive plastic sleeves that help protect the outer surface of an electronic device from scratches. Other cases contain supplemental batteries. When a case with a supplemental battery is attached to an electronic device, a user can perform more functions without running out of battery power. 
     It can be challenging to ensure that an electronic device antenna operates properly in the presence of an external case. The materials of the case may affect antenna operation. For example, metal structures associated with a battery or other components may interfere with the normal operation of an electronic device antenna and dielectric materials may load an antenna. If care is not taken, wireless performance for an electronic device may be degraded in the presence of a removable case. 
     It would therefore be desirable to be able to provide improved removable cases for electronic devices such as electronic devices with antennas. 
     SUMMARY 
     An electronic device may be provided with a removable case. The removable case may include a connector that mates with a connector port in the electronic device. The removable case may include a battery to provide the electronic device with supplemental power. 
     The removable case may have a body that is configured to receive the electronic device. When the electronic device is received within the body, the connector of the removable case may mate with the connector port in the electronic device. 
     The electronic device may include wireless circuitry with one or more antennas. An antenna in the electronic device may have resonating element structures such as inverted-F antenna resonating element structures, slot antenna resonating element structures, and other resonating elements. The antenna in the electronic device has the potential of becoming detuned due to the presence of material in the removable case. 
     To restore antenna performance in an electronic device that has been inserted into a removable case, the removable case may be provided with supplemental antenna structures. The supplemental antenna structures may overlap antenna resonating element(s) in the electronic device, thereby returning the antenna so that the antenna exhibits a desired frequency response. 
     If desired, the supplemental antenna structures may be provided with tunable circuitry. The tunable circuitry can be adjusted to restore antenna performance when the electronic device is mounted in the removable case or can otherwise be adjusted to tune antenna performance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device and a mating removable case in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device and an associated case in accordance with an embodiment. 
         FIG. 3  is a interior view of a portion of an electronic device having an antenna and an overlapping supplemental antenna structure in a case in accordance with an embodiment. 
         FIG. 4  is a graph showing how desired antenna performance may be achieved by incorporating supplemental antenna structures into a case in accordance with an embodiment. 
         FIG. 5  is a diagram showing how conductive structures such as metal patches or other supplemental antenna structures in a case may overlap portions of an antenna in an electronic device to tune the antenna in accordance with an embodiment. 
         FIG. 6  is diagram showing how supplemental antenna structures in a case that include tunable circuitry may be capacitively coupled to an antenna in a device in accordance with an embodiment. 
         FIG. 7  is a diagram showing how a removable case may have a tunable antenna element such as a monopole element that is near-field coupled to an antenna in a device in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with removable external cases. The removable external cases may contain supplemental components such as a supplemental battery to extend battery life. An illustrative electronic device and a mating removable case are shown in the exploded perspective view of  FIG. 1 . As shown in  FIG. 1 , electronic device  10  may have a rectangular shape and case  200  may have a body such as body  202  with a corresponding rectangular recess. Rectangular recess  240  of body  202  may be configured to receive a rectangular device such as electronic device  10  of  FIG. 1 . Electronic devices and cases of other shapes may be used, if desired. For example, a case may have a folding cover, may have the shape of a sleeve that slides over an electronic device, may have a shape that attaches to only one end of an electronic device, or may have other suitable shapes. The example of  FIG. 1  is merely illustrative. 
     Device  10  may include one or more antennas such as loop antennas, inverted-F antennas, planar inverted-F antennas, slot antennas, monopole antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. The conductive electronic device structures may include conductive housing structures and internal structures (e.g., brackets, metal members that are formed using techniques such as stamping, machining, laser cutting, etc.), and other conductive electronic device structures. The housing structures may include peripheral structures such as peripheral conductive structures that run around the periphery of an electronic device. The peripheral conductive structure may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for electronic device  10 . Antennas may also be formed using an antenna ground plane formed from conductive housing structures such as metal housing midplate structures and other internal device structures. Rear housing wall structures may be used in forming antenna structures such as an antenna ground. 
     Electronic device  10  may be a portable electronic device or other suitable electronic device. For example, electronic device  10  may be a laptop computer, a tablet computer, a somewhat smaller device such as a wristwatch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a handheld device such as a cellular telephone, a media player, an electronic stylus, or other small portable device. Device  10  may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, or other suitable electronic equipment. 
     Device  10  may include a housing such as housing  12 . Housing  12  may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     The rear face of housing  12  may have a planar housing wall. The rear housing wall may be formed from metal with one or more regions that are filled with plastic or other dielectric. Portions of the rear housing wall that are separated by dielectric in this way may be coupled together using conductive structures (e.g., internal conductive structures) and/or may be electrically isolated from each other. 
     Device  10  may, if desired, have a display such as display  14 . Display  14  may be mounted on the opposing front face of device  10  from the rear housing wall. Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. 
     Display  14  may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. A display cover layer such as a layer of clear glass or plastic, a layer of sapphire, a transparent dielectric such as clear ceramic, fused silica, transparent crystalline material, or other materials or combinations of these materials may cover the surface of display  14 . Buttons such as button  24  may pass through openings in the cover layer. The cover layer may also have other openings such as an opening for speaker port  26 . 
     Housing  12  may include peripheral housing structures such as structures  16 . Structures  16  may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, structures  16  may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges (as an example). Peripheral structures  16  or part of peripheral structures  16  may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ). Peripheral structures  16  may also, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, by forming curved sidewalls that extend upwards as integral portions of a rear housing wall, etc.). 
     Peripheral housing structures  16  may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, or a peripheral conductive housing member (as examples). Peripheral housing structures  16  may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral housing structures  16 . 
     It is not necessary for peripheral housing structures  16  to have a uniform cross-section. For example, the top portion of peripheral housing structures  16  may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral housing structures  16  may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral housing structures  16  may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral housing structures  16  serve as a bezel for display  14 ), peripheral housing structures  16  may run around the lip of housing  12  (i.e., peripheral housing structures  16  may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, housing  12  may have a conductive rear surface. For example, housing  12  may be formed from a metal such as stainless steel or aluminum. The rear surface of housing  12  may lie in a plane that is parallel to display  14 . In configurations for device  10  in which the rear surface of housing  12  is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  16  as integral portions of the housing structures forming the rear surface of housing  12 . For example, a rear housing wall of device  10  may be formed from a planar metal structure and portions of peripheral housing structures  16  on the sides of housing  12  may be formed as vertically extending integral metal portions of the planar metal structure. Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . The planar rear wall of housing  12  may have one or more, two or more, or three or more portions. 
     Display  14  may include conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. Housing  12  may include internal structures such as metal frame members, a planar housing member (sometimes referred to as a midplate) that spans the walls of housing  12  (i.e., a substantially rectangular sheet formed from one or more parts that is welded or otherwise connected between opposing sides of member  16 ), printed circuit boards, and other internal conductive structures. These conductive structures, which may be used in forming a ground plane in device  10 , may be located in the center of housing  12  under active area AA of display  14  (e.g., the portion of display  14  that contains a display module for displaying images). 
     In regions such as regions  22  and  20 , openings may be formed within the conductive structures of device  10  (e.g., between peripheral conductive housing structures  16  and opposing conductive ground structures such as conductive housing midplate or rear housing wall structures, a printed circuit board, and conductive electrical components in display  14  and device  10 ). These openings, which may sometimes be referred to as gaps, may be filled with air and/or solid dielectrics such as plastic, glass, ceramic, polymers with fiber filler material (e.g., fiber composites), sapphire, etc. 
     Conductive housing structures and other conductive structures in device  10  such as a midplate, traces on a printed circuit board, display  14 , and conductive electronic components may serve as a ground plane for the antennas in device  10 . The openings in regions  20  and  22  may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element from the ground plane, may contribute to the performance of a parasitic antenna resonating element, or may otherwise serve as part of antenna structures formed in regions  20  and  22 . If desired, the ground plane that is under active area AA of display  14  and/or other metal structures in device  10  may have portions that extend into parts of the ends of device  10  (e.g., the ground may extend towards the dielectric-filled openings in regions  20  and  22 ). 
     In general, device  10  may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device  10  may be located at opposing first and second ends of an elongated device housing (e.g., at ends  20  and  22  of device  10  of  FIG. 1 ), along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of these locations. The arrangement of  FIG. 1  is merely illustrative. 
     Portions of peripheral housing structures  16  may be provided with gap structures. For example, peripheral housing structures  16  may be provided with one or more peripheral gaps such as gaps  18 , as shown in  FIG. 1 . The gaps in peripheral housing structures  16  may be filled with dielectric such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. Gaps  18  may divide peripheral housing structures  16  into one or more peripheral conductive segments. There may be, for example, two peripheral conductive segments in peripheral housing structures  16  (e.g., in an arrangement with two gaps), three peripheral conductive segments (e.g., in an arrangement with three gaps), four peripheral conductive segments (e.g., in an arrangement with four gaps, etc.). The segments of peripheral conductive housing structures  16  that are formed in this way may form parts of antennas in device  10 . If desired, gaps may extend across the width of the rear wall of housing  12  and may penetrate through the rear wall of housing  12  to divide the rear wall into different portions. Polymer or other dielectric may fill these housing gaps (grooves). 
     In a typical scenario, device  10  may have upper and lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device  10  in region  22 . A lower antenna may, for example, be formed at the lower end of device  10  in region  20 . The antennas may be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme. 
     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, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc. 
     Case  200  may have a body such as body  202 . Body  202  may be formed from plastic and/or other materials. For example, body  202  of case  200  may be formed from injection molded plastic. Other insulating and/or conductive materials may be used in forming body structures such as body  202  if desired (e.g., ceramic, glass, organic materials, metal, fiber composite materials and other materials formed from fibers, etc.). Rectangular recess  240  may be shaped to receive electronic device  10 . If desired, other shapes may be formed in body  202  to receive device  10 . The configuration of  FIG. 1  is illustrative. 
     A battery and other components may be mounted within body  202  of case  200 . Device  10  may have a connector port with a connector such as female connector  130 . Connector  130  may have signal pins and power pins (sometimes referred to as contacts, signal paths, or signal lines). For example, connector  130  may have 5-20 contacts, 16 contacts, 8 contacts, more than 3 contacts, or fewer than 32 contacts. In some embodiments, connector  130  may be a standardized connector such as USB-A, USB-A Mini or Micro, USB-C, the Lightning connector by Apple Inc., or any other standardized or proprietary connector. Case  200  may have a mating connector such as male connector  204 . When device  10  is mounted in case  200 , connector  204  and connector  130  may be coupled to each other (i.e., the contacts of connector  204  may mate with corresponding contacts in connector  130 ). The battery in case  200  may supply supplemental power to device  10  by routing power signals to the circuitry of device  10  through power pins in connectors  204  and  130 . 
     Connector  204  may be coupled to female connector  206 . When it is desired to use an accessory or other external equipment with device  10 , an external plug (e.g., a plug on the end of an accessory cable or a plug in a dock) may be inserted into connector  206 . Internal wiring in case  200  may route signals from contacts in plug in connector  206  to corresponding contacts in connector  204 . Because connector  204  is coupled to connector  130 , this routes the signals from the accessory or other external equipment to device  10  (i.e., plugs  204  and  206  serve as a port replicator). 
     A schematic diagram showing illustrative components that may be used in device  10  and case  200  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may be powered by an internal power source such as battery  41 . External power may also be supplied to device  10  through connector  130 . For example, power may be received from battery  210  in case  200  when device  10  has been mounted in case  200  so that connector  204  mates with connector  130 . 
     Device  10  may include control circuitry such as 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. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, MIMO protocols, antenna diversity protocols, 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, 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, fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button  24  of  FIG. 1 ), 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 frequency ranges such as a low communications band from 700 to 960 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 2700 MHz or other suitable frequencies (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, near field communications (NFC) circuitry, 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 such as 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 structures, 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. 
     Case  200  may have control circuitry  216  (e.g., storage and processing circuitry such as circuitry  28  of device  10 ). Control circuitry  216  may have communications circuitry that communicates with corresponding communications circuitry in device  10 , thereby allowing control circuitry  216  and control circuitry  28  to communicate to exchange information (e.g., to transmit and receive commands, etc.). 
     Case  200  may also include supplemental antenna structures  212 . Structures  212  may include parasitic antenna resonating elements and/or antennas and other conductive structures for adjusting antenna  40  and the wireless performance of device  10 . Structures  212  may include conductive structures and circuit components that modify the performance of antennas  40  in device  10  (e.g., to retune an antenna that would otherwise be detuned due to the presence of case  200 . Antenna structures  212  may include antenna structures that are coupled to antennas  40  via a hardwired path (e.g., a ground signal path or other path that passes through connectors  204  and  130 ) and/or that are coupled to antennas  40  via near-field coupling (e.g., capacitive or inductive coupling between antennas  40  and antenna structures  212 ). 
     If desired, supplemental antenna structures  212  may include tunable circuitry such as one or more tunable (adjustable) components  214 . Tunable components  214  may be controlled by control signals from device  10  and/or case  200 . For example, control circuitry  216  may adjust tunable components  214  based on information received from control circuitry  28 . Control circuitry  28  may, as an example, determine that antenna  40  should be retuned due to the presence of case  200  or should be tuned because other criteria have been satisfied. Based on this determination, control circuitry  28  may send commands to case  200  that direct control circuitry  216  to adjust tunable components  214  accordingly. 
     Tunable components  214  may contain switches, tunable inductors, tunable capacitors, or other circuitry that exhibits adjustable electrical properties. Tunable components  214  may be used to adjust the performance of antenna structures  212  and/or antennas  40 . Tunable and/or fixed antenna structures in case  200  such as supplemental antenna structures  212  may be used to help ensure that device  10  operates properly, even in the presence of the structures of case  200  such as dielectric and/or conductive structures that might otherwise adversely affect antenna performance. 
     Connectors  208  in case  200  may include male connector  204  and female connector  206 . Male connector  204  may be coupled with female connector  130  in device  10  when device  10  is mounted within case  200 . Female connector  206  may be configured to receive a plug from external equipment. 
     An interior view of a portion of device  10  showing an illustrative antenna of the type that may be formed in device  10  is shown in  FIG. 3 . Antenna  40  of  FIG. 3  may be formed at end  20 , end  22 , or other portion of device  10 . The configuration for antenna  40  of  FIG. 3  is based on an inverted-F antenna design with a slot resonating element (i.e., antenna  40  of  FIG. 3  is a hybrid inverted-F slot antenna). This is merely illustrative. Antenna  40  may be any suitable type of antenna. For example, the slot portion of antenna  40  of  FIG. 3  may be omitted to form an inverted-F antenna or the inverted-F portion of antenna  40  of  FIG. 3  may be omitted to form a slot antenna, etc. 
     As shown in  FIG. 3 , antenna  40  may be coupled to transceiver circuitry  90 , so that transceiver circuitry  90  may transmit antenna signals through antenna  40  and may receive antenna signals through antenna  40 . 
     Transceiver circuitry  90  may be coupled to antenna  40  using paths such as transmission line path  92 . Transmission line  92  may include positive signal line (path)  94  and ground signal line (path)  96 . Transmission line  92  may be coupled to an antenna feed for antenna  40  that is formed from positive antenna feed terminal  98  and ground antenna feed terminal  100 . Positive signal line  94  may be coupled to positive antenna feed terminal  98  and ground signal line  96  may be coupled to ground antenna feed terminal  100 . If desired, impedance matching circuitry, switching circuitry, filter circuitry, and other circuits may be interposed in the path between transceiver circuitry  90  and antenna  40 . Configurations for antenna  40  that include multiple feeds may also be used. 
     Antenna  40  of  FIG. 3  includes inverted-F antenna resonating element  106  and antenna ground  104 . Ground  104  may be formed from metal portions of housing  12  (e.g., portions of the rear wall of housing  12 , a housing midplate, etc.), conductive structures such as display components and other electrical components, ground traces in printed circuits, etc. For example, ground  104  may include portions such as portions  104 ′ that are formed from metal housing walls, a metal band or bezel, or other peripheral conductive housing structures. 
     Antenna resonating element  106  may be formed from conductive structure  108 . Structure  108  may be formed from peripheral conductive housing structure in device  10  (e.g., a segment of structures  16  of  FIG. 1 ) or other conductive structure. Structure  108  may form a main resonating element arm for inverted-F antenna resonating element  106  and may have left and right ends that are separate from ground structure  104 ′ by peripheral gaps  18 . 
     Conductive structure (resonating element arm)  108  may have long and short branches (located on opposing sides of the antenna feed in the orientation of  FIG. 3 ) that support respective lower and higher frequency antenna resonances (e.g., low band and mid-band resonances). Inverted-F antennas that have opposing branches such as these may sometimes be referred to as T antennas or multi-branch inverted-F antennas. 
     Dielectric  114  may form a gap that separates structure  108  from ground  104 . The shape of the dielectric gap associated with dielectric  114  may form a slot antenna resonating element (i.e., the conductive structures surrounding dielectric  114  may form a slot antenna). The slot antenna resonating element may support an antenna resonance at higher frequencies (e.g., a midband and/or a high band resonance). Higher frequency antenna performance may also be supported by harmonics of the lower-frequency resonances associated with the longer and shorter branches of structure  108 . 
     One or more electrical components such as component  102  may span dielectric gap  114 . Components  102  may include tunable and fixed components such as resistors, capacitors, inductors, switches and other structures to provide tuning capabilities, etc. Components  102  may be used to tune the performance of antenna  40  dynamically during antenna operation or may include only fixed components. 
     Antenna  40  may have a return path (sometimes referred to as a short circuit path or short pin) such as return path  110 . Return path  110  may be coupled between the main inverted-F resonating element arm formed from structure  108  and antenna ground  104  in parallel with the antenna feed formed by feed terminals  98  and  100 . Return path  110  may be formed from a metal member having opposing first and second ends. In the example of  FIG. 3 , return path  110  is formed from a metal structure that has a first end with a terminal  120  coupled to structure  108  of inverted-F antenna resonating element  106  (e.g., on a housing sidewall or other peripheral conductive structure) and has a second end with a terminal  122  coupled to antenna ground  104 . Return path  110  may have other shapes and sizes, as illustrated, for example, by dashed line  110 ′ and illustrative terminal  122 ′. 
     The presence of case  200  may affect the operation of the structures associated with antenna  40 . For example, case  200  may include plastic and other dielectric materials that serve to load antenna  40  when device  10  is installed within case  200  and/or metal in case  200  may affect the resonances associated with antenna  40 . When antenna  40  is affected in this way, there is a potential for antenna  40  to become detuned. When detuned, the antenna resonances of antenna  40  become shifted to lower and/or higher frequencies, degrading antenna performance. 
     Case  200  may use supplemental antenna structures  212  to compensate for potential reductions in antenna performance due to antenna detuning. For example, an antenna resonance associated with slot antenna resonating element  114  may shift downwards in frequency when antenna  40  is loaded with dielectric in case  200 . To compensate for this undesired detuning of antenna  40 , a conductive structure such as metal patch  220  or other supplement antenna structure  212  may be incorporated into case  200 . The location of metal patch  220  may be selected so that metal patch  220  adjusts the frequency response of antenna  40  when device  10  is installed within case  200 . As shown in  FIG. 3 , for example, when case  200  is use to cover device  10 , metal patch  220  may overlap a part of slot antenna resonating element  114 , thereby truncating end portion  222  of slot  114 . The presence of metal patch  220  shortens slot  114  so that the frequency response of antenna  40  will be shifted upwards in frequency by an amount that is sufficient to counteract the downwards shift in frequency produced by the dielectric loading of case  200 . Antenna  40  will therefore be able to exhibit the same frequency response regardless of whether or not device  10  is installed within case  200 . 
       FIG. 4  is a graph in which antenna performance (standing wave ratio SWR) has been plotted as a function of operating frequency for various operating conditions. The frequency range of  FIG. 4  may cover midband and high band cellular telephone frequencies or other suitable frequency ranges. When antenna  40  (e.g., antenna  40  of  FIG. 3  or other suitable antenna) is operated in free space and device  10  is not covered by case  200 , antenna  40  may exhibit a frequency response of the type shown by curve  250 . Curve  250  shows how antenna  40  exhibits a resonance at desired operating frequency f 1 . When antenna  40  is installed in a case without a compensating supplemental antenna structure, dielectric loading from the cases may detune the antenna. In particular, antenna  40  may exhibit a frequency response of the type given by curve  252 . In this situation, the peak response of antenna  40  has shifted to an undesirably low frequency f 2  (i.e., antenna  40  has been detuned by the case). When antenna  40  is installed in case  200 , supplemental antenna structures  214  such as metal patch  220  of  FIG. 3  or other metal structures overlap slot  114 , so the length of slot  114  will be shortened and the frequency response of antenna  40  will be shifted upwards to a response of the type shown by curve  254 . As this example demonstrates, incorporation of a metal patch in case  200  that overlaps the end of a slot resonating element in antenna  40  when device  10  is installed in case  200  can help ensure that antenna  40  operates satisfactorily, whether or not device  10  is installed in case  200 . 
     In the illustrative example of  FIG. 3 , metal patch  222  overlaps one of the ends of slot antenna resonating element  114 . If desired, other types of antenna structures may be tuned by structures in case  200 . Consider, as an example, the illustrative inverted-F antenna of  FIG. 5 . As shown in  FIG. 5 , antenna  40  includes inverted-F antenna resonating element  106  and antenna ground  104 . Antenna resonating element  106  may include antenna resonating element arm  108  (e.g., an arm with one or more branches), return path  110 , and an antenna feed formed from positive antenna feed terminal  98  and ground antenna feed terminal  100 . Case  200  may include one or more supplemental antenna structures such as supplemental antenna structures  212 A,  212 B,  212 C, and  212 D. Structure  212 A may be placed over return path  110  when case  200  is used to cover device  10  and may result in an upwardfrequency tuning of the antenna resonance associated with antenna  40 . Structure  212 B may overlap end  256  of antenna resonating element  108  and may shift the frequency response of antenna  40  to a lower frequency. Structure  212 C may be overlap arm  108  between end  256  and return path  110  and may also be used to shift the frequency response of antenna  40  to a lower frequency. Illustrative structure  212 D may have portions that overlap both end portion  256  of arm  108  and an opposing portion of ground  104  and may help shift the frequency response of antenna  40  to a lower frequency. Other types of supplemental antenna structures may be used to tune antenna  40  of  FIG. 5  when device  10  is installed within case  200  if desired. The configurations of  FIG. 5  are merely illustrative. 
     In the illustrative example of  FIG. 6 , antenna  40  has been formed from slot  114  in ground plane  104 . Slot  114  may form the only resonating element in antenna  40  or antenna  40  may include additional resonating element structures. Antenna  40  may be fed using antenna feed terminals such as positive antenna feed terminal  98  and ground antenna feed terminal  100 . Supplemental antenna structures  212  of  FIG. 6  include first metal patch  212 - 1 , second metal patch  212 - 2 , and adjustable components such as switches  258  and  260  (or adjustable inductors, etc.). There may be fewer switches (or other adjustable components  214 ) in antenna structures  212  or more switches in antenna structures  212 . The configuration of  FIG. 6  is merely illustrative. 
     Metal patch  212 - 1  may be capacitively coupled to the portions of ground  104  that are overlapped by metal patch  212 - 1 . Metal patch  212 - 2  may likewise be capacitively coupled to ground  104  on an opposing side of slot  114 . Tunable components  214  such as components  258  and  260  (e.g., switches or other adjustable electrical components) may be controlled by control circuitry  216  (which may, in turn, be controlled by information received from control circuitry  28  in device  10  over connectors  130  and  204 ). When device  10  is mounted in case  200 , antenna  40  may become detuned due to the presence of dielectric in case  200  that loads antenna  40  or due to the presence of other structures in case  200  (e.g., metal structures, etc.). Structures  212  are capacitively coupled to opposing sides of slot  114  and are therefore shorted to ground  104  at these locations when operating at radio frequencies, so switches  258  and  260  bridge slot  114 . By adjusting switches  258  and  260  (or other components  214  that bridge slot  114 ), the length of slot  114  can be dynamically controlled. For example, when it is desired to configure slot  114  to exhibit a length of L 1 , switches  258  and  260  may be opened. When it is desired to reduce the length of slot  114  to L 2 , switch  258  may be placed in an open state while switch  260  may be closed. The length of slot  114  may be further shortened to length L 3  by closing switch  258 . 
     As this example demonstrates, the use of tunable components in supplemental antenna structures  212  of case  200  allows antenna  40  to be tuned during operation (e.g., to compensate for detuning experienced as a result of dielectric loading by case  200  or other types of antenna detuning or to otherwise ensure that antenna  40  is covering desired frequencies). Tunable arrangements of the type shown in  FIG. 6  may be used in tuning an inverted-F antenna, a loop antenna, a patch antenna, a slot antenna, a planar inverted-F antenna, a hybrid antenna that includes resonating elements of more than one type, or any other suitable antenna  40 . The configuration of  FIG. 6  in which supplemental antenna structures  212  and switches  258  and  260  overlap a slot antenna resonating element is merely illustrative. If desired, components  258  and  260  may be tunable inductors, tunable capacitors, circuits that include one or more tunable inductors, capacitors, switches, or other adjustable circuitry, or any other tunable circuits for adjusting antenna performance for antenna  40 . 
     Another illustrative configuration for supplemental antenna structures  212  of case  200  is shown in  FIG. 7 . In the example of  FIG. 7 , device  10  includes antenna  40  (e.g., an inverted-F-slot antenna or other antenna). Connectors  204  and  130  mate with each other when device  10  is inserted within case  200 . The presence of case  200  has the potential to detune antenna  40  due to dielectric loading. To compensate for this detuning, case  200  may be provided with supplemental antenna structures  212  such as tunable monopole element  262 . Element  262  may have an end such as end  264  that is grounded to ground  104  of antenna  40  through a conductive path in connectors  130  and  204 . Element  262  may also have an opposing end such as end  266 . Element  262  may be a monopole antenna resonating element that is formed by metal traces on a printed circuit, plastic carrier, or other substrate, a strip of metal foil, wire, or other conductive structures that extend between end  264  and end  266 . Element  262  may be a parasitic antenna resonating element that is near-field coupled to antenna  40 . If desired, one or more tunable components such as tunable component  214  (e.g., a switch, a tunable inductor, etc.) may be interposed within element  262 . Component  214  may be controlled by control signals from circuitry  216  and/or circuitry  28 , so that antenna  40  can be retuned to compensate for detuning from case  200  or so that antenna  40  can be otherwise adjusted. 
     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: 20150414
Publication Date: 20170516
Grant Date: 20170516
Priority Date: 20150414
Inventors: IRCI ERDINC
AYALA VAZQUEZ ENRIQUE
HU HONGFEI
PASCOLINI MATTIA
CABALLERO RUBEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M1/0262", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/04", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04M1/0262", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/04", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 57129041