PATENT DOCUMENT

Publication Number: US-10237657-B2
Application Number: US-201615255801-A
Country: US
Kind Code: B2

Title: Wireless headset antennas

Abstract:
An accessory such as a wireless headset may have an antenna for transmitting and receiving wireless signals. First and second earbuds may be coupled to different ends of a housing for the accessory. A rigid flex printed circuit board in the housing may include a rigid printed circuit portion. The rigid printed circuit portion may include first and second rigid printed circuit layers. A first portion of a flexible printed circuit may be interposed between the first and second rigid layers. A second portion of the flexible printed circuit may extend from an end of the rigid layers and may be wrapped around the first rigid layer. Planar inverted-F antenna resonating element, antenna shorting, and antenna feeding traces may be formed on the second portion of the flexible printed circuit. The efficiency of the antenna may be undisturbed by the presence of a user&#39;s body adjacent to the accessory.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having opposing first and second housing walls; 
 a rigid flex printed circuit board mounted within the electronic device housing, wherein the rigid flex printed circuit board has a rigid printed circuit portion and a flexible printed circuit portion that extends from an end of the rigid printed circuit portion, the flexible printed circuit portion is folded over a surface of the rigid printed circuit portion and has a distal end that is interposed between the first housing wall and the surface of the rigid printed circuit portion, and the rigid printed circuit portion is interposed between the distal end of the flexible printed circuit portion and the second housing wall; and 
 a planar inverted-F antenna having an antenna resonating element and an antenna ground, wherein the antenna ground is formed on the rigid printed circuit portion and the antenna resonating element is formed from a conductive trace on the flexible printed circuit portion of the rigid flex printed circuit. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the rigid printed circuit portion of the rigid flex printed circuit board comprises a flexible printed circuit layer and a first rigid printed circuit layer attached to the flexible printed circuit layer. 
     
     
       3. The electronic device defined in  claim 2 , wherein the rigid printed circuit portion of the rigid flex printed circuit board further comprises a second rigid printed circuit layer attached to the flexible printed circuit layer, wherein the flexible printed circuit layer is interposed between the first and second rigid printed circuit layers. 
     
     
       4. The electronic device defined in  claim 3 , wherein the flexible printed circuit portion of the rigid flex printed circuit board comprises a portion of the flexible printed circuit layer that is free from the first and second rigid printed circuit layers. 
     
     
       5. The electronic device defined in  claim 1 , further comprising:
 a dielectric support structure interposed between the distal end of the flexible printed circuit portion and the rigid printed circuit portion. 
 
     
     
       6. The electronic device defined in  claim 5 , further comprising:
 a layer of adhesive that attaches the distal end of the flexible printed circuit portion to the dielectric support structure. 
 
     
     
       7. The electronic device defined in  claim 5 , further comprising:
 an alignment post that attaches the dielectric support structure to the rigid printed circuit portion. 
 
     
     
       8. The electronic device defined in  claim 1 , further comprising:
 an electronic component mounted to the surface of the rigid printed circuit portion; and 
 a conformal metal layer that is formed over the electronic component and the surface of the rigid printed circuit portion, wherein the conformal metal layer forms a portion of the antenna ground of the planar inverted-F antenna. 
 
     
     
       9. The electronic device defined in  claim 1 , wherein the planar inverted-F antenna further comprises a shorting trace that is formed on the flexible printed circuit portion and that couples the antenna resonating element arm to the antenna ground. 
     
     
       10. The electronic device defined in  claim 9 , wherein the planar inverted-F antenna further comprises a feed arm trace that is formed on the flexible printed circuit portion. 
     
     
       11. The electronic device defined in  claim 9 , further comprising:
 an impedance matching trace formed on the flexible printed circuit portion between the antenna resonating element arm and the shorting trace, wherein the antenna resonating element arm has a first width and the impedance matching trace has a second width that is greater than the first width. 
 
     
     
       12. The electronic device defined in  claim 1 , wherein the rigid-flex printed circuit board is formed at a first end of the housing and the electronic device further comprises:
 a battery formed at a second end of the housing that opposes the first end of the housing; and 
 control circuitry that is mounted to the rigid-flex printed circuit board and powered by the battery. 
 
     
     
       13. The electronic device defined in  claim 12 , further comprising a band structure that couples the first end of the housing to the second end of the housing. 
     
     
       14. The electronic device defined in  claim 13 , further comprising:
 a first earbud coupled to the second end of the housing by a first conductive line; and 
 a second earbud coupled to the first end of the housing by a second conductive line, wherein the control circuitry provides audio signals to the first and second earbuds. 
 
     
     
       15. The electronic device defined in  claim 14 , wherein the control circuitry is configured to process stereo audio signals received by the planar inverted-F antenna from external equipment, the control circuitry is configured to convey signals from a right channel of the stereo audio signals to the first earbud, and the control circuitry is configured to convey signals from a left channel of the stereo audio signals to the second earbud. 
     
     
       16. The electronic device defined in  claim 15 , further comprising:
 a microphone interposed on the second conductive line, wherein the control circuitry is configured to receive audio signals from the microphone and to transmit the audio signals received from the microphone to the external equipment over the planar inverted-F antenna. 
 
     
     
       17. The electronic device defined in  claim 16 , wherein the first end of the housing forms a first side of the housing, the second end forms a second side of the housing, the first side, the second side, a third side, and a fourth side of the housing extend between the first and second housing walls, a graphic component is formed on the second housing wall, the planar inverted-F antenna further comprises a shorting arm trace on the flexible printed circuit portion that is coupled between the antenna resonating element arm and the antenna ground, a feed arm trace on the flexible printed circuit portion that is coupled to the antenna resonating element arm, a first antenna feed terminal coupled to the feed arm trace, and a second antenna feed terminal coupled to the antenna ground, and the shorting arm trace is interposed between the feed arm trace and the third side of the housing. 
     
     
       18. A wireless accessory that performs wireless communications with external equipment, the wireless accessory comprising:
 a housing body; 
 a first earbud coupled to a first end of the housing body; 
 a second earbud coupled to a second end of the housing body; 
 a rigid flex printed circuit board mounted within the housing body; 
 a planar inverted-F antenna formed on the rigid flex printed circuit board; 
 radio-frequency transceiver circuitry mounted to the rigid flex printed circuit board, wherein the radio-frequency transceiver circuitry is configured to receive audio data from the external equipment over the planar inverted-F antenna; and 
 control circuitry mounted to the rigid flex printed circuit board, wherein the control circuitry is configured to provide the audio data to the first and second earbuds. 
 
     
     
       19. The wireless accessory defined in  claim 18 , wherein the housing body has opposing first and second ends, further comprising:
 a battery mounted within a first portion of the housing body located at the first end, wherein the rigid flex printed circuit board is mounted within a second portion of the housing body located at the second end. 
 
     
     
       20. The wireless accessory defined in  claim 19 , further comprising:
 a semi-rigid band coupled between the first portion and the second portion of the housing body; and 
 conductive lines in the semi-rigid band, wherein the conductive lines convey power signals between the control circuitry and the battery and the conductive lines convey the audio data from the control circuitry and the first earbud. 
 
     
     
       21. The wireless accessory defined in  claim 20 , wherein the semi-rigid band has a curved shape that accommodates a body of a user, the housing body has an inner face that is configured to face the body of the user during operation of the wireless accessory, and the housing body has an outer face that is configured to face away from the body of the user during operation of the wireless accessory. 
     
     
       22. The wireless accessory defined in  claim 21 , wherein the rigid flex printed circuit board comprises a flexible printed circuit having a first portion that is interposed between first and second rigid printed circuit layers and a second portion that extends from and end of the first and second rigid printed circuit layers. 
     
     
       23. The wireless accessory defined in  claim 22 , wherein the second portion of the flexible printed circuit is wrapped around the first rigid printed circuit layer and is interposed between the first rigid printed circuit layer and the outer face of the housing body, and the planar inverted-F antenna comprises a resonating element arm trace formed on the second portion of the flexible printed circuit. 
     
     
       24. The wireless accessory defined in  claim 23 , wherein the planar inverted-F antenna further comprises an antenna ground, a short circuit trace coupled between the resonating element arm trace and the antenna ground, a feed arm trace, a first antenna feed terminal coupled to the feed arm trace, a second antenna feed terminal coupled to the antenna ground, and the feed arm trace and the short circuit trace are formed on the second portion of the flexible printed circuit. 
     
     
       25. A wireless headset that is configured to wirelessly receive audio signals from an electronic device, the wireless headset comprising:
 first and second rigid printed circuit layers; 
 a flexible printed circuit having a first portion that is interposed between the first and second rigid printed circuit layers and a second portion that extends from an end of the first and second rigid printed circuit layers, wherein the second portion of the flexible printed circuit is wrapped around the first rigid printed circuit layer; and 
 a planar inverted-F antenna having a planar antenna resonating element trace, an antenna ground, a short circuit trace coupled between the antenna ground and the planar antenna resonating element trace, and an antenna feed trace coupled to the planar antenna resonating element trace, wherein the planar antenna resonating element trace, the short circuit trace, and the antenna feed trace are formed on the second portion of the flexible printed circuit. 
 
     
     
       26. The wireless headset defined in  claim 25 , further comprising:
 radio-frequency transceiver circuitry mounted to a selected one of the first and second rigid printed circuit layers, wherein the radio-frequency circuitry is configured to receive the audio signals from the electronic device over the planar inverted-F antenna; 
 a first antenna feed terminal coupled to the antenna feed trace; 
 a second antenna feed terminal coupled to the antenna ground; and 
 a radio-frequency transmission line that couples the radio-frequency transceiver circuitry to the first and second antenna feed terminals. 
 
     
     
       27. The wireless headset defined in  claim 26 , further comprising:
 a first speaker; 
 a second speaker; and 
 control circuitry, wherein the control circuitry is configured to convey the audio signals to the first and second speakers.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless circuitry. 
     Electronic devices such as electronic accessories for cellular telephones, computers, and other electronic equipment often include wireless circuitry. For example, headsets or earbuds are available that communicate wirelessly with cellular telephones and other equipment. 
     Challenges can arise in implementing wireless communications circuitry in a compact device such as a headset. If care is not taken, antennas will not perform effectively. This can make it difficult or impossible to achieve desired levels of wireless communications performance. 
     It would therefore be desirable to be able to provide devices such as headsets with improved wireless circuitry. 
     SUMMARY 
     An accessory such as a wireless headset may have an antenna for transmitting and receiving wireless signals. The accessory may have a housing with a main body portion. A first speaker or earbud may be coupled to a first end of the main body portion. A second speaker or earbud may be coupled to an opposing second end of the main body portion. A battery may be formed at the first and a rigid flex printed circuit board may be formed at the second end of the main body portion. 
     The rigid flex printed circuit board may include a rigid printed circuit portion. The rigid printed circuit portion may include first and second rigid printed circuit layers. A first portion of a flexible printed circuit may be interposed between the first and second rigid printed circuit layers. A second portion of the flexible printed circuit may extend from an end of the first and second rigid printed circuit layers. The second portion of the flexible printed circuit may be free from the first and second rigid printed circuit layers. The second portion of the flexible printed circuit may be folded or wrapped around the first rigid printed circuit layer. A distal end of the second portion of the flexible printed circuit may be interposed between an outward-facing surface of the housing and the first rigid printed circuit layer. The second rigid printed circuit layer may be interposed between an inward-facing surface of the housing and the first portion of the flexible printed circuit. 
     A planar inverted-F antenna may be formed on the rigid flex printed circuit. The planar inverted-F antenna may have a planar antenna resonating element trace, an antenna ground, a shorting trace coupled between the planar antenna resonating element trace and the antenna ground, an a feed arm trace coupled to the planar antenna resonating element trace. The feed arm trace, the shorting trace, and the planar antenna resonating element trace may be formed on the folded portion of the flexible printed circuit. During operation of the accessory, a given edge of the housing may be closer to a user&#39;s skin than the other edges of the housing (e.g., an edge of the housing that faces upward during use of the accessory). The shorting trace may be interposed between the given edge of the housing and the feed arm trace on the flexible printed circuit. When configured in this way, the planar inverted-F antenna may be provided with an optimal antenna efficiency that is not significantly impacted by the presence of the user&#39;s body during operation of the accessory. 
     A radio-frequency transceiver and control circuitry may be formed on the rigid printed circuit portion of the rigid flex printed circuit board. The radio-frequency transceiver may receive audio signals or other wireless signals from external equipment such as a cellular telephone over the planar inverted-F antenna. The control circuitry may convey the audio signals to the first and second speakers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device with wireless circuitry in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device such as a wireless headset in accordance with an embodiment. 
         FIG. 3  is a schematic diagram of an illustrative antenna of the type that may be used in an electronic device in accordance with an embodiment. 
         FIG. 4  is a top-down view of an illustrative antenna of the type that may be used in an electronic device in accordance with an embodiment. 
         FIG. 5  is a cross-sectional side view showing how an illustrative antenna may be wrapped around a substrate for placement within an electronic device in accordance with an embodiment. 
         FIG. 6  is a top-down view showing how an illustrative antenna may be wrapped around a substrate for placement within an electronic device in accordance with an embodiment. 
         FIG. 7  is a diagram showing how a conductive conformal coating may be formed on a substrate and used as a portion of an antenna ground in accordance with an embodiment. 
         FIG. 8  is a diagram showing how an illustrative electronic device having an antenna of the type shown in  FIGS. 3-7  may be oriented with respect to the body of a user during operation of the electronic device in accordance with an embodiment. 
         FIG. 9  is a graph of antenna performance (antenna efficiency) that shows how an illustrative antenna of the type shown in  FIGS. 3-7  may exhibit optimal antenna efficiency when placed in proximity to the body of a user in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device of the type that may be provided with wireless circuitry is shown in  FIG. 1 . Device  10  of  FIG. 1  may be a wireless accessory such as a wireless headset, wireless headphones, wireless earbuds, or other small portable accessory of the type that is used in conjunction with another electronic device  8 . Electronic device  8  may be a cellular telephone, portable computer, watch, media player, or other host equipment. If desired, device  10  may be a different type of electronic equipment. Configurations in which device  10  is a wireless accessory may sometimes be described herein as an example. 
     Devices such as device  10  may communicate wirelessly with external electronic equipment such as device  8  over wireless communications link  36 . Wireless communications link  36  may be a cellular telephone link (e.g., a wireless link at frequencies of 700 MHz to 2700 MHz or other suitable cellular telephone frequencies), may be a wireless local area network link operating at 2.4 GHz, 5 GHz, or other suitable wireless local area network frequencies, may be a Bluetooth® link operating at 2.4 GHz, may involve millimeter wave communications, may involve near-field communications, or may involve wireless communications in other communications bands. Configurations in which device  10  operates at 2.4 GHz to support short-range communications such as Bluetooth® communications may sometimes be described herein as an example. 
     As shown in  FIG. 1 , device  10  (e.g., a headset or other accessory) may include control circuitry such as storage and processing circuitry  16 . Storage and processing circuitry  16  may include storage such as 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  16  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processor integrated circuits, application specific integrated circuits, etc. 
     Storage and processing circuitry  16  may be used to run software on device  10 . The software may handle communications, may process sensor signals and take appropriate action based on the processed sensor signals (e.g., to turn on or off functions in device  10 , to start or stop audio playback, etc.), and may handle other device operations. To support interactions with external equipment  8 , storage and processing circuitry  16  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  16  include wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi® and WiGig), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc. 
     Device  10  may include microphones, speakers, tone generators, and other audio components (see, e.g., one or more speakers  14 ). Microphones may gather voice signals and/or ambient noise signals for noise cancellation functions. Speakers may play back sound for a user. Speakers  14  may, if desired, be located within one or more earbuds associated with device  10 . For example, speakers  14  may be formed in a left earbud that is configured to be placed within the left ear of a user and a right earbud that is configured to be placed within the right ear of the user. Tone generators and other sound output devices may generate other audible or non-audible outputs. Sensors and other components  20  in device  10  may include proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors, etc.), force sensors, buttons, magnetic sensors, accelerometers and other components for measuring device orientation and/or motion, strain gauge sensors, vibrators, connector components, printed circuit board structures, wiring structures, etc. 
     Device  10  may include battery  18  to provide power to the circuitry of device  10 . Battery  18  may be, for example, a rechargeable battery. Battery  18  may be recharged wirelessly (e.g., by providing device  10  with wireless power) or may be recharged via a wired connection between external equipment and device  10 . Configurations in which battery  18  is not rechargeable (e.g., in which battery  18  is a replaceable non-rechargeable battery) may also be used. Components  20  may include, if desired, a connector that is configured to receive a cable or other structure that, when connected to the connector, provide power to device  10  for charging battery  18 . 
     Electronic device  10  may include wireless circuitry for supporting wireless communications with external equipment. The wireless circuitry may include radio-frequency transceiver  22  and one or more antennas such as antenna  40 . Antenna  40  may have a feed that includes positive antenna feed terminal  42  and ground antenna feed terminal  44 . Transmission line  30  may be used to couple radio-frequency transceiver circuitry  22  to antenna  40 . Transmission line  30  may have a positive signal path such as line  32  and a ground signal path such as line  34 . Transmission lines in device  10  such as transmission line  30  may include coaxial cable paths, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the transmission lines, if desired. 
     Circuitry  22  may include any desired circuitry associated with the transmission and reception of radio-frequency signals using antenna  40 . For example, circuitry  22  may include baseband processor circuitry, amplifier circuitry (e.g., low noise and/or power amplifier circuitry), mixing circuitry such as up-converter and/or down-converter circuitry, converter circuitry such as analog-to-digital converter circuitry and/or digital-to-analog converter circuitry, etc. 
     Antenna  40  may be formed using any suitable antenna type. For example, antenna  40  may be an antenna with a resonating element that is formed from a loop antenna structure, a patch antenna structure, an inverted-F antenna structure, a slot antenna structure, a planar inverted-F antenna structure, a helical antenna structure, a monopole, a dipole, hybrids of these designs, etc. If desired, antenna  40  may include tunable circuitry and control circuitry  16  may be used to select an optimum setting for the tunable circuitry to tune antenna  40 . Antenna adjustments may be made to tune antenna  40  to perform communications in a desired frequency range or to otherwise optimize antenna performance. Antenna  40  may also be implemented using a fixed (non-tunable) configuration if desired. 
     The components of device  10  may be housed within device housing  12 , which may sometimes be referred to as an enclosure or case. Housing  12  may, for example, be formed from of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel or aluminum), other dielectrics such as silicone or rubber, or a combination of any two or more of these materials. If desired, housing  12  may include an internal frame structure that is enclosed within other housing structures such as a silicone or rubber outer casing. Housing  12  may, if desired, include earbud housing structures that enclose speakers  14  but that are otherwise separated from other portions of housing  12 . For example, portions of housing  12  may include holes or other openings that align with speakers  14  to allow sound to be conveyed to or from speakers  14 . 
       FIG. 2  is a perspective view of electronic device  10 . In the illustrative configuration of  FIG. 2 , device  10  is a portable wireless accessory such as a wireless headset (e.g., a wireless pair of headphones). Other configurations may be used for device  10  if desired. The example of  FIG. 2  is merely illustrative. 
     As shown in  FIG. 2 , device  10  may include a main device body  49 . Main device body  49  may be enclosed within a main body housing portion  12 M of housing  12 . Device  10  may include earbuds such as right earbud  50 R and left earbud  50 L. Right earbud  50 R may be enclosed within a portion  12 R of housing  12  whereas left earbud  50 L is enclosed with a portion  12 L of housing  12 . Right earbud  50 R may be coupled to main body portion  49  of device  10  by conductive line  52 R. Left earbud  50 L may be coupled to main body portion  49  by conductive line  52 L. Conductive lines  52  may be covered using a portion of housing  12  (e.g., rubber wire coverings or other structures). Conductive lines  52  may convey audio signals from circuitry within main body  49  to earbuds  50  and/or may convey microphone signals to main body  49 . 
     The example shown in  FIG. 2  in which earbud housing portions  12 R and  12 L are separate from main housing body  12 M is merely illustrative. If desired, housing  12  may include a continuous housing structure that extends from main body portion  12 M to earbuds  50  (e.g., conductive lines  52 R and  52 L may be enclosed within housing  12  or may be formed using conductive wire that is separate from housing  12 ). 
     Main body  49  may include a first body portion  54  formed at a first end of housing  12 M and a second body portion  56  formed at an opposing second end of housing  12 M. Body portion  54  may be coupled to body portion  56  by band  58 . Band  58  may be flexible or semi-rigid and may have a curved shape to accommodate a user&#39;s head or neck. For example, when operating device  10 , the user&#39;s head or neck may be located at axis  88 . Band  58  may curve around axis  88  so that device  10  remains in place on the user during use. Band  58  may, if desired, include rigid or semi-rigid shape retention structures that allow band  58  to maintain a curved shape (e.g., even when device  10  is not being worn by a user). 
     If desired, battery  18  ( FIG. 1 ) may be located within portion  54  of main device body  49 . Portion  54  may therefore sometimes be referred to herein as battery portion  54 , battery region  54 , battery case  54 , battery body  54 , or battery box  54 . Circuitry such as control circuitry  16 , transceiver circuitry  22 , transmission line  30 , and antenna  40  may be located within portion  56  of main device body  49 . For example, control circuitry  16 , transceiver circuitry  22 , transmission line  30 , and antenna  40  may be formed on a substrate such as a main logic board that is located within housing  12 M at body portion  56 . The main logic board may include rigid printed circuit board structures, flexible printed circuit board structures, a combination of rigid and flexible printed circuit board structures (e.g., so-called “rigid-flex” circuit board structures), integrated circuit structures, or any other desired structures. Portion  56  of main body  49  may therefore sometimes be referred to herein as main logic board portion  56 , control portion  56 , main logic board region  56 , main logic board box  56 , control body  56 , control region  56 , or main logic board body  56 . 
     Control portion  56  of device  10  may include connector structures such as connector  70 . Connector  70  may be configured to receive a cable or other structure that is used to provide power or other signals to device  10 . In one suitable arrangement, connector  70  is located at lower edge  78  of body portion  56 . If desired, connector  70  may be located at upper edge  76 , right edge  74 , or left edge  72  of body portion  56 , or elsewhere on device  10 . In scenarios where battery  18  is formed at region  54 , power lines may be run through band  58  to provide power for charging battery  18  at region  54 . Once charged, battery  18  may convey power to components within main logic region  56  over the power lines within band  58 . 
     Upper edge  76  may extend across the entire length of main housing body  49 . For example, upper edge  76  may extend across control portion  56  from edge  72  to edge  74 , across the length of band  58 , and across the length of battery portion  76 . Similarly, lower edge  78  may extend across the entire length of main housing body  49 . For example, lower edge  78  may extend across control portion  56 , across the length of band  58 , and across the length of battery portion  76 . The height of control portion  56  and/or battery portion  54  (e.g., the length of side  72 ) may, if desired, be greater than the height of band  58 . A first face (side or surface)  64  of body  49  may extend continuously across the entire length of body  49 . Similarly, a second opposing face  62  of body  49  may continuously extend across the entire length of body  49 . 
     Antenna  40  may be located within main logic board region  56  of body  49 . Antenna  40  may receive radio-frequency signals from external device  8 . Control circuitry  16  may be located within main logic board region  56  and may extract audio signals from the radio-frequency signals received over antenna  40 . Control circuitry  16  may convey the audio signals to left earbud  50 L over line  52 L. Band  58  may include conductive audio lines that carry the audio signals to right earbud  50 R (e.g., over line  52 R). 
     Right earbud  50 R may have an area such as area  80 R and left earbud  50 L may have an area such as area  80 L through which sound may be emitted from speakers  14 . Area  80 R may be formed from an opening in housing portion  12 R whereas area  80 L may be formed from an opening in housing portion  12 L. Openings  80  may be provided with mesh structures or other protective structures that protect speakers  14  within housing portions  12 R and  12 L. 
     If desired, an input device such as communications box  66  may be interposed on left conductive line  52 L. Communications box  66  may include one or more buttons that accept input from the user of device  10 . For example, communications box  66  may include volume adjustment buttons or sliders, playback control buttons, or other input components. 
     If desired, communications box  66  may include a microphone that generates audio signals in response to mechanical sound (e.g., voice signals or other sound signals generated in response to the voice of the user or other ambient sounds). The audio signals generated at communications box  66  may be conveyed to control circuitry in main logic region  56  over conductive line  52 L. Radio-frequency transceiver  22  may generate radio-frequency signals based on the audio signals and may transmit the signals to external device  8  using antenna  40 . This example is merely illustrative. If desired, communications box  66  may be omitted. 
     Antennas such as antenna  40  may be affected by the presence of nearby objects. For example, antenna  40  may exhibit an expected antenna efficiency when operated in free space in the absence of nearby external objects, but may exhibit a different antenna efficiency when operated in the presence of external objects. When operating device  10  (e.g., when listening to audio using device  10 ), a user typically wears device  10  on their person. For example, the user may wear device  10  so that band  58  wraps around their head or neck. Wearing device  10  may bring the user&#39;s body (e.g., the skin of a user&#39;s neck or head), clothes, or other external objects within the vicinity of antenna  40 . If care is not taken, antenna  40  may exhibit a deteriorated antenna efficiency when device  10  is worn on the body of a user (e.g., the efficiency of the antenna may decrease because the impedance of the antenna has been changed due to loading from the user&#39;s body). 
     Antenna  40  and other components within device  10  may be configured so that the impact of the user&#39;s body on antenna  40  during operation of device  10  is minimized. For example, antenna  40  and other components in device  10  may be configured so that antenna  40  is located as far away from the user&#39;s body as possible when device  10  is being worn by the user. Device  10  may include structures that help to ensure that device  10  maintains an optimal orientation with respect to the user&#39;s body and an optimal antenna efficiency during use (e.g., an orientation that allows the user&#39;s body to have as little of an effect on the efficiency of antenna  40  as possible). 
     The optimal orientation may, for example, be an orientation at which edge  76  of body  49  is facing upwards (e.g., towards the head of the user) and at which edge  78  is facing downward (e.g., towards the torso of the user). In the optimal orientation, the face  64  of device body  49  (e.g., side or wall  64  of housing  12 M) faces outwards (e.g., away from the user&#39;s body or neck) whereas face  62  faces inwards (e.g., towards the user&#39;s body or neck). Face  64  may therefore sometimes be referred to herein as outer face  64 , outer wall  64 , or outer side  64  and face  62  may sometimes be referred to herein as inner face  62 , inner wall  62 , or inner side  62 . 
     In order to help maintain the optimal orientation, band  58  may include one or more bend retention structures. The bend retention structures may include rigid metal structures such as a length of rigid wire or other rigid or semi-rigid structures. The bend retention structures may allow band  58  to maintain curve around axis  88  (e.g., to conform to the body of the user) while also preventing torsion or twisting of band  58  (e.g., in the direction as shown by arrow  86 ). By preventing twisting of band  58 , the bend retention structures may help to ensure that edge  76  of housing body  49  faces upwards, edge  78  faces downwards, face  62  faces inwards, and face  64  faces outwards when device  10  is being used. Maintaining the curved shape of housing portion  12 M around axis  88  may, for example, encourage or require the user to place device  10  around their neck or head in the optimal orientation when beginning use of device  10 . 
     Other structures may be used to ensure that device  10  is at an optimal orientation when being worn by the user. If desired, a graphic component such as element  68  may be located on outer side  64  of device body  49  (e.g., at control region  56 , at battery region  54 , or elsewhere on body  49 ). Graphic component  68  may be, for example, a logo, artistic design, or other structures to be viewed by the user or others. If desired, graphic component  68  may include light-emitting components or display structures (e.g., that convey visual content to the user or others). As graphic component  68  provides visual information to the user or others, forming graphic component  68  on outer side  64  of device body  49  may encourage or effectively require the user to wear device  10  in the optimal orientation during use (e.g., in order to properly view visual element  68 , the user may need to wear device  10  in the optimal orientation). 
     Right earbud  50 R may be configured to provide audio to the right ear of the user and left earbud  50 L may be configured to provide audio to the left ear of the user during operation. For example, right earbud  50 R may play audio signals from the right channel of a stereo audio feed through speaker port  80 R whereas left earbud  50 L plays audio signals from the left channel of the stereo audio feed through speaker port  80 L. Housing  12 R of right earbud  50 R may have a shape or configuration that allows earbud  50 R to fit within the right ear of the user whereas housing  12 L has a shape or configuration that allows earbud  50 L to fit within the left ear of the user. Housing  12 L may be unwearable or uncomfortable to wear in the user&#39;s right ear and housing  12 R may be unwearable or uncomfortable to wear in the user&#39;s left ear, for example. If desired, left earbud  50 L may include a label  82 L that identifies left earbud  50 L as the earbud for use in the user&#39;s left ear, whereas right earbud  50 R includes a label  82 R that identifies right earbud  50 R as the earbud for use in the user&#39;s right ear. Configuring earbuds  50  in this manner may encourage or require the user to wear device  10  at an optimal orientation for antenna  40 . 
     The example of  FIG. 2  in which device  10  includes earbuds  50  is merely illustrative. In general, earbuds  52  may be replaced with any other desired structures for housing speakers  14 . For example, earbuds  52  may be replaced by over-the-ear structures such as ear cups or cans, if desired. 
       FIG. 3  is a schematic diagram of antenna  40  within main logic board region  56  of device  10 . In the example of  FIG. 3 , antenna  40  is an inverted-F antenna and has inverted-F antenna resonating element  58  and antenna ground  60 . Antenna  40  may be fed by coupling transmission line  30  ( FIG. 1 ) to antenna feed arm  62  and ground  60 . Antenna feed arm  62  may be coupled to resonating element arm  65 . Positive (signal) antenna feed terminal  42  may be coupled to antenna feed arm  62 . Ground antenna feed terminal  44  may be coupled to ground  60 . Return path  66  (i.e., a short circuit path) may be coupled between antenna resonating element arm  65  and ground  60  in parallel with feed  62 . The resonant frequency of antenna  40  may, for example, be determined by the length of resonating element arm  65 . 
     Antenna ground  60  may be formed from ground traces in a printed circuit or other substrate, metal portions of a battery, metal housing structures, metal portions of internal device components, other conductive ground structures, or a combination of these structures in device  10 . Antenna resonating element  58  may be formed from metal printed circuit traces and/or other conductive structures in device  10 . 
     If desired, antenna  40  may be a planar inverted-F antenna. When configured as a planar inverted-F antenna, resonating element arm  65  may be formed using a conductive structure that extend across a planar lateral area above ground  60  (e.g., a conductive sheet, a conductive trace, conductive foil, etc. that is separated from ground  60  by a predetermined distance). The perimeter of the conductive structure forming resonating element arm  65  may help to define the resonant frequency of antenna  40 , for example. 
       FIG. 4  is a top-down diagram showing how antenna  40  may be implemented using planar inverted-F antenna structures formed from conductive structures on a dielectric substrate. As shown in  FIG. 4 , resonating element arm  65 , feed arm  62 , short circuit arm  66 , and ground plane  60  may be formed using conductive structures such as conductive traces on a dielectric substrate  100 . 
     Dielectric substrate  100  may be a flexible printed circuit (e.g., a printed circuit formed from a flexible polymer substrate such as a layer of polyimide or a sheet of other flexible polymer material) such as a flexible printed circuit board. The conductive traces of antenna  40  may be formed (e.g., patterned) on a surface of flexible printed circuit board  100  or on an internal layer of flexible printed circuit board  100 . 
     Flexible printed circuit board  100  may be folded, bent, or wrapped around axis  110  as shown by arrow  112 . As shown in the example of  FIG. 4 , flexible printed circuit board  100  has been unfolded and placed flat. When placed within portion  56  of device  10 , flexible printed circuit board  100  may be folded around axis  110 . This may allow antenna  40  to occupy less volume within device  10  than in scenarios where board  100  is laid flat. Bend  112  may allow antenna resonating element arm  65  to be placed within a plane that is at a predetermined distance with respect to antenna ground  60 . Bend  112  around axis  110  may be, for example, a 180 degree bend as an example. In general, bend  112  may be any angle greater than 90 degrees and less than or equal to 180 degrees. 
     In one suitable arrangement, the portion of flexible printed circuit board  100  that extends from ground plane  60  may sometimes be referred to herein as flexible tail portion  136 . In this scenario, the portion of flexible printed circuit board  60  may be held in a rigid configuration (e.g., by rigid structures above and/or below flexible printed circuit board  100 ) whereas tail region  136  remains in a flexible configuration (e.g., thereby allowing tail  136  to flex or bend such as around axis  110 ). Tail portion  136  at distal end  120  may be substantially parallel to ground  60  when substrate  100  is bent around axis  110 . 
     In the example of  FIG. 4 , short circuit arm  66  and feed arm  62  are bent around axis  110  (e.g., axis  110  overlaps antenna  40  at arms  66  and  62 ). Bending flexible printed circuit board  100  in this manner may allow antenna resonating element arm  65  to be oriented in a desired direction (e.g., in a direction such that antenna resonating element arm  65  is not affected by the user&#39;s body while operating device  10 ) while still being parallel to and separated from ground  60  by a predetermined distance. This is example merely illustrative. In general, axis  110  may overlap any desired portion of the antenna traces formed on circuit board  100 . 
     Short circuit arm  66  may have a width  104  whereas resonating element arm  65  has a width  114 . Resonating element arm trace  65  may be coupled to short circuit arm  66  and feed arm  62  by matching trace  102  (e.g., resonating element arm  65  may extend from matching trace  102  towards distal end  120  of flexible printed circuit  100 ). Matching trace  102  may have a width  116 . Feed arm  62  may have a width  118 . Width  114  may be the same as or may be different from width  116 . Width  114  may be the same as or may be different from width  104 . Width  116  may be the same as or may be different from width  104 . Width  118  may be the same as or may be different from widths  114 ,  116 , and/or  104 . In one suitable arrangement, width  114  is greater than width  104 , width  104  is greater than width  118 , and width  116  is greater than width  114 . 
     If desired, the ratio of width  114  to width  116  may be configured to provide a desired impedance match for antenna resonating element arm  114 . The ratio of width  114  to width  116  may, if desired, be selected to tune the performance of antenna  40 . Additional matching circuitry (e.g., a network of resistive, capacitive, inductive, and/or switching components) may be interposed on transmission line path  32  between feed terminal  42  and transceiver  22  (e.g., to provide a desired impedance match between antenna  40  and transmission line  30 ). 
     The example of  FIG. 4  is merely illustrative. If desired, antenna resonating element arm  65  may have any desired shape. For example, arm  65  may have a bent or winding shape, may include multiple branches, may include straight and/or curved edges, may have edges that extend at non-perpendicular angles with respect to each other, or may have any other desired shape. In general, antenna resonating element  65  may be provided with a desired shape and perimeter so that antenna  40  operates at a desired resonant frequency. Similarly, conductive traces  102 ,  60 ,  66 , and  62  may have any desired shape and may include straight, curved, or bent edges oriented at any desired angles. Ground plane  60  may be formed from a layer of conductive material on printed circuit board  100  and/or from other conductive components in control portion  56  of device body  49 . 
       FIG. 5  is a cross-sectional side view showing how flexible printed circuit board  100  may be bent around axis  110  and placed within main logic region  56  of device body  49 . In particular,  FIG. 5  shows a cross-sectional view of main logic region  56  of device body  49 , where the plane of the page is defined by the x-y axes of the perspective view shown in  FIG. 2  (e.g., a view as taken in the direction of arrow  78  of  FIG. 2 ). 
     As shown in  FIG. 5 , printed circuit  130  may be formed within housing  12 M at control region  56  of device body  49 . Printed circuit  130  may be, for example, the main logic board or motherboard for device  10 . If desired, printed circuit  130  may be implemented using “rigid flex” printed circuit material. In a “rigid flex” printed circuit, part of the printed circuit has rigid printed circuit board layers and at least one flexible printed circuit layer whereas another part of the printed circuit has only the flexible printed circuit layers. In the example of  FIG. 5 , portion  132  of printed circuit  130  has rigid printed circuit board layers  134  (e.g., at least a first rigid layer  134 - 1  and a second rigid layer  134 - 2 ) and at least one flexible printed circuit layer formed using flexible printed circuit  100 , whereas another part of printed circuit  130  has only flexible printed circuit layers formed by flexible printed circuit  100  (e.g., tail portion  136  of flexible printed circuit  100  is free from rigid layers such as layers  134 ). Portion  132  of printed circuit  130  may sometimes be referred to herein as rigid portion  132  (e.g., because rigid layers  134 - 1  and  134 - 2  prevent bending of portion  132 ). Flexible printed circuit  100  may be interposed between first and second rigid layers  134 - 1  and  134 - 2  in main logic board  130 . Rigid layers  134  may be formed from a material such as fiberglass-filled epoxy or other rigid materials. Metal layers within or on rigid layers  134  may be used to form a portion of antenna ground  60  for antenna  40  if desired. Conductive through-vias or other vertical interconnects may be used to convey signals between layer  134 - 1 ,  100 , and  134 - 2  in board  130 . 
     Conductive traces  122  may be formed in or on flexible printed circuit  100 . Conductive traces  122  may be used to form resonating element arm  65 , matching trace  102 , shorting trace  66 , feed arm trace  62 , and/or ground plane  60  of  FIG. 4 . Other components may be mounted on or in tail portion  136  of the flexible printed circuit  100  in rigid-flex printed circuit  130  if desired. 
     Components such as components  140  may be mounted on rigid layer  134 - 1 . Components such as components  142  may be mounted on rigid layer  134 - 2 . Components  140  and  142  may include, for example, components used in forming control circuitry  16 , components  20 , and transceiver circuitry  22  of  FIG. 1  and/or any other desired circuitry. 
     When main logic board  130  is placed within portion  56  of device body  49 , rigid printed circuit layer  134 - 2  may be interposed between flexible printed circuit  100  and inner side  62  of housing  12 M. The planar surfaces of rigid printed circuit layers  134  may extend from first side  72  of main logic region  56  (e.g., the side of device body  49  from which left earbud conductor  52 L extends) to second side  74  of main logic region  56  (e.g., the side of main logic portion  56  that is connected to band  58 ). When device  10  is being worn by a user (e.g., in the optimal orientation), inner side  62  may face the body (e.g., neck or head) of the user. 
     Metal structures (e.g., ground plane structures) in or on rigid layers  134 - 1  and  134 - 2  and/or components  140  may serve as electromagnetic shielding structures that help to block the electromagnetic influence of external objects adjacent to inner side  62  of housing  12 M and antenna  40 . If desired, additional electromagnetic shielding structures (e.g., one or more sheets of metal) may be provided to enhance electromagnetic isolation of antenna  40  from external objects adjacent to inner side  62 . 
     As shown in  FIG. 5 , tail portion  136  of flexible printed circuit  100  may extend from the end of rigid portion  132  of main logic board  130  towards side  72  of device portion  56  and around axis  110 . Flexible tail portion  136  may further extend over rigid printed circuit layer  134 - 1  so that distal end  120  of tail  136  extends from side  72  towards side  74  of device portion  56 . When configured in this way, distal end  120  of flexible printed circuit  100  and antenna resonating element arm  65  are interposed between rigid printed circuit layer  134 - 1  and outer side  64  of housing  12 M. Flexible tail  136  may include a first portion that extends parallel to rigid layer  134 - 1  and a second portion that extends substantially perpendicular to the first portion and rigid layer  134 - 1  between the first portion and rigid layer  134 - 1  (e.g., at the bend in the flexible tail). Distal end  120  of flexible printed circuit  100  may extend substantially parallel to rigid printed circuit layer  134 , for example. This may serve to orient antenna resonating element arm  65  away from the user&#39;s body while the user is operating device  10  with the optimal orientation. In addition, this may serve to separate antenna resonating element arm  65  from the top surface of rigid layer  134 - 1  or antenna ground  60  by a predetermined distance. The predetermined distance may be, for example, a distance that is less than 1.8 mm and greater than 0.8 mm or any other desired distance. Antenna resonating element arm  65  may transmit radio-frequency signals to external device  8  and may receive radio-frequency signals from external device  8  through outer side  64  of housing  12 M. Radio-frequency signals transmitted from antenna resonating element arm  65  towards inner side  62  may be blocked or reflected by ground plane  60  or other metal structures within main logic board  130 . 
     One or more dielectric support structures such as dielectric support structure  150  may be interposed between flexible tail  136  and rigid printed circuit layer  134 - 1 . Dielectric support structure  150  may be, for example, a plastic support structure, ceramic support structure, or other dielectric structure. Dielectric support structure  150  may provide mechanical support to flexible printed circuit tail  136  while the flexible printed circuit is bent around axis  110  (e.g., flexible printed circuit tail  136  may be wrapped around an edge of support structure  150 ). If desired, distal end  120  of flexible printed circuit  100  may be attached to plastic support structure  150  using an adhesive such as adhesive layer  152 . Adhesive layer  152  may include pressure sensitive adhesive, thermally activated adhesive, light cured adhesive, or any other desired adhesive. Adhering flexible printed circuit tail  136  to plastic support structure  150  may help flexible printed circuit  100  to maintain a bent configuration around axis  110 . 
     This example is merely illustrative. If desired, other attachment mechanisms may be used to secure distal end  120  to plastic support  150 . For example, screws, fastener structures, pin structures, clip structures, biasing structures that bias distal end  120  towards support  150 , or any other desired attachment mechanisms may be used. If desired, alignment structures such as structures  154  may be used to secure plastic support structure  150  in place over rigid circuit  134 . Alignment structures  154  may include pin structures, alignment posts, adhesive, or any other desired structures. If desired, alignment structures  154  may also be used to secure distal end  120  of flexible tail  136  in place. For example, alignment structures  154  may be alignment posts that extend through notches in plastic support  150  and/or flexible circuit  100  to hold end  120  in place. 
     Wrapping flexible printed circuit  100  in this way (e.g., so that antenna resonating element arm  65  is interposed between rigid printed circuit layer  134 - 1  and outer housing wall  64 ) may allow antenna  40  to occupy a minimal amount of space within device body portion  56  while also minimizing the impact of the user&#39;s body on the efficiency of antenna  40 . Placement of device  10  on the user&#39;s body in the optimal orientation during use (e.g., with inner side  62  facing the user&#39;s body and outer side  64  facing away from the user&#39;s body) may further mitigate impacts of the user&#39;s body on the efficiency of antenna  40 . 
       FIG. 6  is a top-down view of antenna  40  within portion  56  of device  10  (e.g., as viewed from side  64  of device  10 ). In particular,  FIG. 6  shows a top-down view of main logic region  56  of device body  49 , where the plane of the page is defined by the x-z axes of  FIGS. 2 and 5  (e.g., a view as taken in the direction of arrow  64  of  FIG. 5 ). In the diagram of  FIG. 6 , the portion of housing  12 M covering side  64  of device body  49  is not shown for the sake of clarity. 
     As shown in  FIG. 6 , flexible tail  136  of flexible printed circuit  100  may be wrapped around axis  110  and over the top surface of rigid printed circuit layer  134 - 1 . Conductive traces  22  forming shorting arm  66  and feed arm  62  may wrap around axis  110 . Matching trace  102  may extend from arms  66  and  62  towards resonating element arm trace  65 . Resonating element arm trace  65  may extend from matching trace  102  towards distal end  120 . 
     When device  10  is being operated by a user, side  76  of device body  49  faces upwards (e.g., towards the head of the user) whereas side  78  of device body  49  faces downwards (e.g., towards the shoulders of the user). In this orientation, the user&#39;s body may have a greater electromagnetic influence on side  76  of device body  49  than side  78 . This may be because the user&#39;s skin, which generally has a greater effect on the loading of antenna  40  than the user&#39;s clothing, may be closer to side  76  than side  78  during operation. 
     In practice, the presence of the user&#39;s body (skin) may have less effect on the antenna efficiency of antenna  40  when shorting arm  66  is closer to the user&#39;s body than feed arm  62  than when the user&#39;s body is closer to feed arm  62  than shorting arm  66 . In the example of  FIG. 6 , shorting trace  66  of antenna  40  may be interposed between feed trace  62  and upper side  76  of housing  12 M. In this way, shorting trace  66  is located closer to the user&#39;s body (skin) during operation than feeding trace  62 . This may further minimize the impact of the presence of the user&#39;s body on the antenna efficiency of antenna  40 , thereby maximizing or otherwise optimizing the efficiency and overall performance of antenna  40 . Maintaining device  10  in the optimal orientation (e.g., with side  76  facing the head of the user, side  78  facing the torso of the user, side  62  facing the body of the user, and side  64  facing away from the user) may further ensure that shorting arm  66  is closer to the user&#39;s body than arm  62 , thereby ensuring that the antenna continues to operate with optimal antenna efficiency. 
     If desired, bend retention structures such as structures  160  may be formed within device body  49 . As an example, bend retention structures  160  are formed using a length of rigid wire or other metal structures. Rigid wire  160  may have a first portion  162  that extends along the length of band  58  ( FIG. 2 ) to battery enclosure  54  in device body  49  and a second portion  164  that is embedded or otherwise attached to main logic board  130 . Second portion  164  may be, for example, adhered to a surface of main logic board  130  or embedded (molded) within layer  134 - 1 ,  110 , and/or  134 - 2  ( FIG. 5 ). Second portion  164  may be oriented substantially perpendicular to first portion  162 . When configured in this way, structure  162  may prevent twisting of band  58  (e.g., as shown by arrow  86  of  FIG. 2 ), thereby ensuring that short arm  66  of antenna  40  remains oriented upwards (e.g., at a location that is closer to the user&#39;s skin than arm  62 ) during operation of device  10 . 
     As shown in  FIG. 6 , connector structure  70  may be mounted to main logic board  130 . Connector  70  may extend through housing  12 M at bottom side  78 . This may expose connector  70  so that a cable or other battery charging structure may be connected to main logic board  130  for charging battery  18 . 
     Conductive paths such as conductive lines (wires)  170  may extend from side  74  of main logic board  130  through band  58 . Conductive wires  170  may include conductive power lines for charging battery  18  in device portion  54  and for powering main logic board  130  using energy stored on battery  18 . Conductive wires  170  may include audio lines for conveying right channel audio signals from main logic board  130  to right ear bud  50 R. If desired, conductive wires  170  may include control lines or other paths for conveying control signals. 
     Conductive paths such as conductive wires  172  may extend from side  72  of main logic board  130  through path  52 L. Conductive wires  172  may include power lines that convey power signals to communications box  66 . Conductive wires  172  may include audio lines that convey left channel audio signals from main logic board  130  to left ear bud  50 L. The audio lines in wires  172  may convey microphone signals from communications box  66  to main logic board  130 . If desired, control signals may be conveyed over control lines in wires  172  (e.g., for controlling communications box  66  or for controlling components on main logic board  130 ). 
     If desired, a conformal metal coating may be formed on main logic board  130  for further isolating antenna  40  from the body of a user.  FIG. 7  is a diagram showing how a conformal metal coating may be formed on a surface of main logic board  130 . As shown in  FIG. 7 , conformal coating  200  may be formed using metal or another conductor placed over the top surface of rigid printed circuit board layer  134 - 1 . Coating  200  may be a layer of foil, stamped metal, or other conductive structures that conform to the shape of components  140 . Coating  200  may serve as an electromagnetic shield that prevents the presence of the user&#39;s body adjacent to side  62  from affecting the antenna impedance of antenna  40 . 
     The distance between antenna ground  60  ( FIGS. 3 and 4 ) and antenna resonating element arm  65  may help to determine the bandwidth of antenna  40 . In general, larger distances may provide more bandwidth than shorter distances. Coating  200  may conform to the shape of components  140  formed on the upper surface of layer  134 - 1 . Coating  200  may be connected to ground at one or more locations. In this way, coating  200  may serve as a portion of antenna ground  60  ( FIG. 4 ). By conforming to the shape of components  140  at rigid layer  134 - 1 , the distance between grounded layer  200  and antenna resonating element arm  65  may be maximized, thereby maximizing the bandwidth of antenna  40 . As an example, the portion of coating  200  formed over components  140  may be separated from antenna resonating element arm  65  by a vertical distance of 0.8 mm or more whereas the portion of coating  200  formed on the surface of layer  134 - 1  may be separated from antenna resonating element arm  65  by a vertical distance of less than or equal to approximately 1.8 mm. This example is merely illustrative. If desired, layer  200  may be omitted or formed elsewhere on main logic board  130 . 
       FIG. 7  is a diagram showing how device  10  may be oriented with respect to the body of a user during normal operation. As shown in  FIG. 7 , main body  49  of device  10  is wrapped around the neck of a user such as user  210 . For example, bend retention structures such as structures  160  ( FIG. 6 ) within band  58  may maintain a bend for band  58  around the user&#39;s neck (e.g., around axis  88  as shown in  FIG. 2 ). In an optimal orientation, side  76  of housing body  76  may face upwards towards the head of user  210  (e.g., side  76  is adjacent to the skin of the user&#39;s neck). Side  78  may face downwards towards the shoulders of user (e.g., side  78  is adjacent to the user&#39;s shirt or other clothing). Outer side  64  may face away from user  210  whereas inner side  62  faces towards the user&#39;s body in this configuration. 
     By wrapping antenna flexible printed circuit  100  around axis  110 , antenna resonating element  65  points away from the user&#39;s body so that radio-frequency signals  36  are conveyed through outer side  64 . Metal structures in main logic board  130  (e.g., conformal coating  200  of  FIG. 7  or other structures) may serve as an electromagnetic shield between inner side  62  and antenna  40 . Forming antenna short arm  66  closer to upper side  76  than feed arm  62  may minimize the effect of the skin of user  210  on the antenna efficiency of antenna  40 . Structures such as bend retention structure  160 , labels  82 , visual element  68 , and asymmetric earbud housings  12 R and  12 L may help to ensure that device  10  remains in this optimal orientation during use of device  10 . 
     The example of  FIG. 7  is merely illustrative. If desired, device  10  may be used in other orientations or configurations. For example, band  58  may wrap around the head of user  210  or may be located at any other desired location on user  210 . Device  10  may be used in other scenarios that do not require the user to wear device  10  if desired (e.g., device  10  may be used while placed on a desktop or other surface, etc.). 
     The example of  FIGS. 2-8  in which battery  18  is located at the end of main body  49  that is coupled to right earbud  50 R and main logic board  130  is located at the end of main body  49  that is coupled to left earbud  50 L is merely illustrative. If desired, battery  18  may be formed within band  58  or within control region  56 . If desired, antenna  40  may be formed at any other desired location within device body  49  (e.g., within band  58 , within portion  54 , etc.). Main logic board  130  may be formed in portion  54  of body  49  (i.e., the side of body  49  coupled to right ear bud  50 R) or along band  58  if desired. In the scenario where main logic board  130  is formed in region  54 , battery  18  may be formed in region  56 , in band  58 , or may also be formed in region  54 . In scenarios where main logic board  130  is formed in region  54 , the structures shown in  FIG. 6  may be reflected about the z-axis of  FIG. 6 , for example (e.g., so that antenna resonating element arm  65  faces outer side  64  and arm  66  is interposed between arm  62  and upper side  76 ). 
       FIG. 9  is a graph showing how antenna efficiency varies as a function of frequency for different antenna configurations. Curve  232  illustrates the efficiency of an antenna when placed in the vicinity of the body of user  210  (e.g., in the absence of the features and arrangements described above in connection with  FIGS. 1-8 ). The efficiency of the antenna in this configuration may peak at a level E 1  at resonant frequency F (e.g., a Bluetooth® frequency at 2.4 GHz). This peak efficiency may be relatively low due to loading of the antenna by the user&#39;s skin, for example. Curve  230  illustrates the efficiency of antenna  40  in device  10  when device  10  is placed in the vicinity of the body of a user (e.g., when device  10  is placed on the user&#39;s body during operation such as is shown in  FIG. 8 ). The efficiency of antenna  40  in this configuration may peak at a level E 2  at frequency F, which is much greater than peak efficiency E 1 . Similarly, antenna  40  may exhibit greater efficiency bandwidth (e.g., corresponding to a horizontal width of curve  230 ) than an antenna associated with curve  232 . In this way, the effect on the antenna efficiency of antenna  10  when in the vicinity of the user may be mitigated. 
     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: 20160902
Publication Date: 20190319
Grant Date: 20190319
Priority Date: 20160902
Inventors: MCAULIFFE, ERIN A.
GUTERMAN, Jerzy S.
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/055", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R5/033", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/1427", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03H7/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R3/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0298", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R2201/107", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/0216", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K7/1427", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K2201/055", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2201/107", "inventive": false, "first": false, "tree": "[]"}, {"code": "H05K1/028", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R5/033", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R3/12", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/147", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03H7/38", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0298", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0216", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/181", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/04", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 59798062