PATENT DOCUMENT

Publication Number: US-9634709-B2
Application Number: US-201414477596-A
Country: US
Kind Code: B2

Title: Removable electronic device case with supplemental antenna element

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 case may have a supplemental antenna that restores antenna performance when the device is received within the case. The supplemental antenna may be formed from a monopole antenna resonating element coupled to the antenna ground through the power pin. The monopole element may have a portion that runs parallel to the peripheral conductive housing structures. During operation of the antenna in the electronic device, the supplemental antenna in the case may be indirectly fed by near-field coupling between the supplemental antenna and the antenna of the electronic device.

Claims:
What is claimed is: 
     
       1. 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 mates with the connector port; and 
 a supplemental antenna element that is configured to be near-field coupled to the antenna, wherein the supplemental antenna element has a first segment that is electrically connected to the connector and a second segment that runs parallel to a portion of the antenna, the second segment is configured to be capacitively coupled to the antenna, and the second segment passes under the first segment. 
 
     
     
       2. The removable electronic device case defined in  claim 1  further comprising a battery that supplies supplemental power to the electronic device when the connector mates with the connector port. 
     
     
       3. The removable electronic device case defined in  claim 2  wherein the supplemental antenna element comprises a monopole antenna element. 
     
     
       4. The removable electronic device case defined in  claim 3  wherein the antenna resonates in a communications band at a first frequency in the absence of the body, the antenna resonates in a communications band at a second frequency that is lower than the first frequency when the body is adjacent to the electronic device in the absence of the supplemental antenna element, and the supplemental antenna element in the case resonates in the communications band at the first frequency when the body and the supplemental antenna element are adjacent to the electronic device. 
     
     
       5. The removable electronic device case defined in  claim 3  wherein the monopole antenna element is configured to be coupled to an antenna ground in the electronic device by a ground pin path in the connector. 
     
     
       6. The removable electronic device case defined in  claim 5  further comprising a female connector, wherein a portion of the monopole antenna element is configured to be coupled to the female connector. 
     
     
       7. The removable electronic device case defined in  claim 1  wherein the body is formed at least partly from plastic and has a rectangular recess that is configured to receive the electronic device. 
     
     
       8. The removable electronic device case defined in  claim 1  wherein the supplemental antenna element is configured to be capacitively coupled to a peripheral conductive housing structure that forms part of the antenna in the electronic device. 
     
     
       9. Apparatus, comprising:
 a body formed at least partly from plastic; 
 a battery mounted in the body; 
 a male connector; 
 a female connector coupled to the male connector; 
 a signal path coupled between the battery and the male connector; and 
 a monopole antenna resonating element within the body and having first and second opposing ends, wherein the first end is coupled to a pin in the male connector and a portion of the monopole antenna resonating element is interposed between the male and female connectors. 
 
     
     
       10. The apparatus defined in  claim 9  wherein the body is configured to receive a mating electronic device that has an antenna formed from peripheral conductive electronic device housing structures and the signal path overlaps a gap in the peripheral conductive electronic device housing structures when the body receives the mating electronic device. 
     
     
       11. The apparatus defined in  claim 10  wherein the antenna of the mating electronic device has an antenna ground and wherein the pin in the male connector is coupled to the antenna ground when the body receives the mating electronic device. 
     
     
       12. The apparatus defined in  claim 11  wherein the signal path comprises a flexible printed circuit with metal traces. 
     
     
       13. The apparatus defined in  claim 12  wherein the monopole antenna resonating element is formed from a strip of metal that runs parallel to the peripheral conductive electronic device housing structures when the body receives the mating electronic device. 
     
     
       14. A removable case configured to mate with a cellular telephone having an antenna formed from peripheral conductive electronic device housing structures and an antenna ground, the case comprising:
 a connector that mates with a connector port on the cellular telephone, wherein the connector has a plurality of pins that includes a grounding power pin that is electrically coupled to the antenna ground when the removable case mates with the cellular telephone; 
 a body that receives the cellular telephone; and 
 a supplemental antenna in the body that is configured to be near-field coupled to the antenna in the cellular telephone and that enhances radio-frequency performance by the antenna when the cellular telephone is received by the body, wherein the supplemental antenna has only a single connection to the plurality of pins in the connector, the single connection to the plurality of pins being to the grounding power pin. 
 
     
     
       15. The removable case defined in  claim 14  wherein the cellular telephone has a female connector and the removable case further comprises a male connector that mates with the female connector. 
     
     
       16. The removable case defined in  claim 15  further comprising a battery that supplies power to the male connector. 
     
     
       17. The removable case defined in  claim 16  wherein the supplemental antenna comprises an antenna element having a portion that runs parallel to the peripheral conductive electronic device housing structures when the cellular telephone is received by the body. 
     
     
       18. The removable case defined in  claim 17  wherein the supplemental antenna comprises a monopole resonating element. 
     
     
       19. The removable case defined in  claim 15 , further comprising a male connector that mates with the connector port on the cellular telephone when the removable case mates with the cellular telephone and further comprising a female connector, a portion of the supplemental antenna being interposed between the male and female connectors.

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 of 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 
     A removable case for an electronic device such as a cellular telephone may have a body. The body may be configured to receive the electronic device. A male connector in the case may mate with a female connector in the electronic device. A battery in the case may supply power to the electronic device through a power pin in the male connector. The battery power supplied to the device through the male connector may supplement internal battery power in the electronic device. 
     The electronic device may have an antenna formed from peripheral conductive electronic device housing structures and an antenna ground. The peripheral conductive housing structures may form an inverted-F antenna resonating element. Due to the presence of external structures such as portions of the case, there is a potential for the antenna of the electronic device to become detuned when the electronic device is received within the body of the case. This risk may be addressed by providing the case with a supplemental antenna. The supplemental antenna may be used to restore antenna performance to the electronic device, so that the electronic device antenna performs satisfactorily, even when the electronic device is received within the body of the case. 
     The supplemental antenna may be formed from a monopole antenna resonating element having an end that is coupled to the antenna ground through the power pin or other signal path. The monopole element may have a portion that runs parallel to the peripheral conductive electronic device housing structures and that is capacitively coupled to the peripheral conductive electronic device housing structures. During operation of the antenna in the electronic device, the supplemental antenna in the case may be indirectly fed due to near-field coupling between the supplemental antenna and the antenna of the electronic device. 
    
    
     
       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 associated case in accordance with an embodiment. 
         FIG. 3  is a top interior view of a portion of an electronic device having an antenna and a portion of an associated case having a supplemental antenna in accordance with an embodiment. 
         FIG. 4  is a cross-sectional side view of an illustrative electronic device to which a case with a supplemental antenna has been attached in accordance with an embodiment. 
         FIG. 5  is a top view of a portion of the illustrative electronic device and case of  FIG. 4  in accordance with an embodiment. 
         FIG. 6  is graph in which antenna performance (standing wave ratio SWR) has been plotted as a function of operating frequency for an electronic device during normal operation of the device without a mating case in accordance with an embodiment. 
         FIG. 7  is a graph of antenna performance for the electronic device antenna of  FIG. 6  when the electronic device has been mounted in a case without a supplemental antenna in accordance with an embodiment. 
         FIG. 8  is a graph of antenna performance for the electronic device antenna of  FIG. 7  when the electronic device has been mounted in a case with a supplemental antenna 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 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 mount to only one end of an electronic device, or may have other suitable shape. The example of  FIG. 1  is merely illustrative. 
     Device  10  may include one or more antennas such as loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot 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 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. 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. 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 a supplemental antenna structure such as supplemental antenna element  212 . Element  212  may help ensure that device  10  operates properly, even in the presence of the structures of case  200 . 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 top view of 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. 
     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 . 
     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  108  may have long and short branches (to the 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 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 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 and/or may include 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 . Accordingly, case  200  may be provided with a supplemental antenna element. The supplemental element may help ensure that antenna  40  operates satisfactorily, regardless of whether or not device  10  is mounted within case  200 . 
     A cross-sectional side view of device  10  mounted in case  200  in an illustrative configuration in which case  200  has been provided with a battery and a supplemental antenna element is shown in  FIG. 4 . As shown in  FIG. 4 , case  200  includes plastic enclosure (body)  202 . Battery  210  and support structures such as metal plate  218  may be mounted within body  202 . Flexible printed circuit cable  216  may have a first end that is coupled to the terminals of battery  210  and an opposing second end that is coupled to the power pins of connector  204 . When connector  204  is coupled to connector  130  of device  10 , power from battery  210  is routed to the circuitry of device  10  via connectors  204  and  130 . The signal paths that route power from battery  210  to device  10  may include ground signal path (ground power pin)  214 . 
     The presence of case  200  in the vicinity of device  10  can affect the operation of antenna  40  of device  10 . For example, the capacitance of gap  18  (and therefore the capacitance(s) at the tip(s) of the inverted-F antenna resonating elements formed from peripheral conductive housing structures  108 ) may be affected by the presence of overlapping metal structures such as the metal traces in flexible printed circuit  216 . Connector  204  may overlap gap  114  ( FIG. 3 ), which may also affect antenna performance. The dielectric material of body  202  of case  200  can load antenna  40  and may serve to detune antenna when device  10  is mounted in case  200 . 
     To counteract these influences, case  200  may be provided with a supplemental antenna element such as antenna resonating element  212 . Antenna element  212  may be, for example, a monopole antenna element that is mounted in body  202 . During operation of device  10 , antenna element  212  may form a supplemental monopole antenna that helps extend the performance of antenna  40 , so that device  10  can handle wireless signals with desired levels of antenna efficiency. 
       FIG. 5  is a top view of portions of device  10  and case  200  in the vicinity of antenna  30 . As shown in  FIG. 5 , when device  10  is mounted in case  200 , connector  204  of case  200  may overlap gap  114  between inverted-F antenna resonating element arm  108  and ground  104 . This can influence antenna operation. A ground path such as ground path  214  (e.g., a power pin) may couple ground  104  to a supplemental antenna element such as monopole antenna resonating element  212  or other antenna resonating element structure. Supplemental antenna resonating element  212  may be mounted in body  202  of case  200  and may be coupled to ground  104  via ground path  214 . Element  212  may be formed from machined metal, from stamped metal parts, may be formed for metal traces on a printed circuit, may be formed from metal traces on a plastic carrier (e.g., metal traces patterned using laser-activated surfaces that have been plated with metal), may be formed from strips of metal or wires, or may be formed from other metal antenna structures. 
     In the example of  FIG. 5 , supplemental antenna resonating element  212  has conductive segments such as segments  212 - 1 ,  212 - 2 ,  212 - 3 , and  212 - 4  (e.g., metal strips or other metal structures). End portion  212 - 4 ′ of segment  212 - 4  may pass under segment  212 - 1  of element  212  (i.e., element  212  may wrap under itself). Portion  212 - 2 ′ of element  212  may be coupled to ground structures in connector  216  (if desired). The length of monopole element  212  (i.e., the distance between end portion  212 - 4 ′ of element  212  and ground) may be configured to provide a supplemental antenna resonance at a desired frequency (e.g., a low band frequency) for device  10 . 
     Segment  214 - 4  may be adjacent to peripheral conductive housing structure  108  (e.g., an inverted-F antenna resonating element arm in antenna  40 ). For example, portion  214 - 4  of monopole element  212  may run parallel to structure  108  and may be capacitively coupled to structure  108 . Antenna  40  may be directly fed using an antenna feed formed from positive antenna feed terminal  98  and ground antenna feed terminal  100  of  FIG. 3 . Due to the capacitive coupling between portion  212 - 4  of antenna element  212  and portion  108  of antenna  40 , antenna element  212  will be near-field coupled to antenna  40 . As a result, antenna element  212  (i.e., the supplemental monopole antenna of case  200 ) will be indirectly fed by antenna  40  during operation of antenna  40 . Because antenna  212  is indirectly fed from the near-field electromagnetic coupling between antennas  40  and  212 , antenna  212  will resonate and will contribute to the overall performance of antenna  40 . Antenna  212  therefore serves as a supplemental antenna structure that helps ensure that antenna  40  operates satisfactorily, even in the presence of the potentially adverse influences of body  212 , flexible printed circuit cable  216 , connector  204 , and other structures in case  200 . 
     The influence of case  200  and supplemental antenna element  212  on the antenna operation of antenna  40  in device  10  may be understood with reference to the graphs of  FIGS. 6, 7, and 8 .  FIG. 6  shows the performance of antenna  40  in the absence of case  200 . In this situation, antenna  40  exhibits a desired antenna resonance at frequency f 1 . Frequency f 1  may be centered within a low band such as a communications band at 700-960 MHz or other suitable frequency range desired for the operation of antenna  40 . 
       FIG. 7  shows how antenna  40  can be detuned due to the presence of the structures of case  200  in the absence of supplemental antenna element  212 . As shown in  FIG. 7 , the antenna resonance for antenna  40  may be detuned (e.g., by moving to a lower frequency f 2 ). This may reduce the performance of antenna  40  at the desired operating band at frequency f 1 . 
       FIG. 8  shows the performance of antenna  40  in the presence of case  200  in a scenario in which case  200  incorporates supplemental antenna element  212  of  FIGS. 4 and 5 . As shown in  FIG. 8 , the performance of antenna  40  in the communications band at f 1  may be restored by the presence of supplemental antenna element  212 . There are two frequency peaks in the antenna performance graph of  FIG. 8 . The lower peak at f 2  corresponds to the original detuned performance of antenna  40  (detuned from f 1  to f 2  due to the presence of the structures of case  200  other than element  212 ). The higher peak at f 1  is a resonance produced by indirectly fed monopole antenna element  212 . The peak at f 1  that is due to the presence of supplemental element  212  provides device  10  with satisfactory performance at the communications band centered about frequency f 1 , even though other structures in case  200  are adjacent to device  10 . 
     In general, any suitable antenna structures may be used to serve as a supplemental antenna structure for antenna  40  (e.g., patch antenna structures, loop antenna structures, dipole structures, monopole structures, directly feed structures, indirectly fed structures, inverted-F structures, planar inverted-F structures, strip-shaped elements, elements that include filters or other electrical components, etc. The configuration of  FIGS. 4 and 5  in which the supplemental antenna structure is formed from an indirectly fed monopole element is merely illustrative. 
     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: 20140904
Publication Date: 20170425
Grant Date: 20170425
Priority Date: 20140904
Inventors: HU HONGFEI
AYALA VAZQUEZ ENRIQUE
XU HAO
PASCOLINI MATTIA
CABALLERO RUBEN
IRCI ERDINC
Assignee: APPLE INC
CPC Classifications: [{"code": "H04M1/724092", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/72527", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B1/3888", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/724092", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 53938446