PATENT DOCUMENT

Publication Number: US-8892049-B2
Application Number: US-97411507-A
Country: US
Kind Code: B2

Title: Handheld electronic devices with antenna power monitoring

Abstract:
Handheld electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include an antenna. A radio-frequency coupler may be coupled to the antenna. Transceiver circuitry may be used to transmit and receive radio-frequency signals through the coupler and the antenna. A reflected power detection circuit may be connected to the coupler. When the transceiver circuitry transmits radio-frequency signals, some of the signals are reflected back from the antenna into the coupler. The coupler directs the reflected antenna signals into the reflected power detection circuit. Processing circuitry may analyze a reflected power signal from the reflected power detection circuit to determine whether operation of the antenna is being disrupted by the placement of a user&#39;s hand over the antenna or other proximity effects. If antenna operation is being disrupted, the user may be alerted or other suitable actions may be taken.

Claims:
What is claimed is: 
     
       1. A handheld electronic device comprising:
 an antenna; 
 a radio-frequency coupler that is coupled to the antenna; 
 transceiver circuitry that transmits and receives radio-frequency signals through the coupler and the antenna; and 
 monitoring and control circuitry that monitors how much transmitted signal power is reflected back from the antenna when the transceiver circuitry is transmitting the radio-frequency signals, wherein the monitoring and control circuitry includes processing circuitry that analyzes the monitored reflected transmitted signal power and that alerts a user of the handheld electronic device when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
 
     
     
       2. The handheld electronic device defined in  claim 1  further comprising a display, wherein the processing circuitry displays a visual message to the user of the handheld electronic device on the display when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       3. The handheld electronic device defined in  claim 1  further comprising a display, wherein the processing circuitry displays a visual alert symbol to the user of the handheld electronic device on the display when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       4. The handheld electronic device defined in  claim 1  further comprising a display, wherein the processing circuitry displays alert message text to the user of the handheld electronic device on the display when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       5. The handheld electronic device defined in  claim 1  further comprising a speaker, wherein the processing circuitry presents an audible alert to the user of the handheld electronic device with the speaker when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       6. The handheld electronic device defined in  claim 1  further comprising a vibrating element, wherein the processing circuitry presents a vibrating alert to the user of the handheld electronic device with the vibrating element when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       7. The handheld electronic device defined in  claim 1 , wherein the processing circuitry shuts down communications circuitry on the handheld electronic device to save power when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       8. The handheld electronic device defined in  claim 1 , wherein the processing circuitry locks communications circuitry on the handheld electronic device to save power when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       9. The handheld electronic device defined in  claim 1 , further comprising an additional antenna, wherein the processing circuitry selects the additional antenna in the handheld electronic device to use to transmit the radio-frequency signals when the monitored reflected transmitted signal power indicates that operation of the antenna is being disrupted due to proximity effects. 
     
     
       10. The handheld electronic device defined in  claim 1  wherein the monitoring and control circuitry comprises a power detection diode coupled to the coupler that measures signals that have been reflected back from the antenna to the power detection diode through the coupler. 
     
     
       11. Wireless communications circuitry in a handheld electronic device comprising:
 an antenna; 
 a coupler that is coupled to the antenna; 
 transceiver circuitry that transmits radio-frequency signals through the coupler and the antenna; 
 a reflected power detection circuit that is connected to the coupler, wherein during data transmission by the transceiver circuitry, radio-frequency signals are reflected back into coupler from the antenna and are directed by the coupler to the reflected power detection circuit; and 
 processing circuitry that processes reflected antenna power measurements from the reflected power detection circuit and that provides an alert to a user of the handheld electronic device when the reflected antenna power measurements indicate that operation of the antenna has been disrupted due to proximity effects. 
 
     
     
       12. The wireless communications circuitry defined in  claim 11  wherein the transceiver circuitry comprises analog to digital converter circuitry that converts analog signals from the reflected power detection circuit into digital signals and wherein the processing circuitry compares digitized reflected power measurement signals from the analog to digital converter to a threshold to determine whether operation of the antenna is being disrupted due to proximity effects from a body part of the user of the handheld electronic device. 
     
     
       13. A method of operating a handheld electronic device having an antenna, transceiver circuitry, and monitoring and control circuitry, comprising:
 transmitting radio-frequency signals through the antenna from the transceiver circuitry; 
 with the monitoring and control circuitry, monitoring how much transmitted signal power is reflected back from the antenna when the transceiver circuitry is transmitting the radio-frequency signals to determine whether operation of the antenna is being disrupted due to proximity effects; and 
 providing a blocked antenna indicator for a user of the handheld electronic device that informs the user that an object is covering the antenna when the monitoring and control circuitry determines that operation of the antenna is being disrupted due to proximity effects. 
 
     
     
       14. The method defined in  claim 13  wherein providing the blocked antenna indicator comprises displaying a visual alert on a display in the handheld electronic device. 
     
     
       15. The method defined in  claim 13  wherein providing the blocked antenna indicator comprises displaying a visual signal strength indicator on a display in the handheld electronic device and displaying an alert symbol over the signal strength indicator. 
     
     
       16. The method defined in  claim 13  wherein providing the blocked antenna indicator comprises displaying a textual alert message on a display in the handheld electronic device. 
     
     
       17. The method defined in  claim 13  further comprising shutting down at least some circuitry on the handheld electronic device to save power when it is determined by the monitoring and control circuitry that operation of the antenna is being disrupted due to proximity effects.

Description:
BACKGROUND 
     This invention relates generally to wireless communications, and more particularly, to wireless handheld electronic devices in which monitoring and control circuitry is used to measure wireless signal powers. 
     Handheld electronic devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. 
     Due in part to their mobile nature, handheld electronic devices are often provided with wireless communications capabilities. Handheld electronic devices may use long-range wireless communications to communicate with wireless base stations. For example, cellular telephones may communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. Handheld electronic devices may also use short-range wireless communications links. For example, handheld electronic devices may communicate using the WiFi® (IEEE 802.11) band at 2.4 GHz and the Bluetooth® band at 2.4 GHz. Communications are also possible in data service bands such as the 3 G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System). Some handheld devices receive Global Positioning System (GPS) signals at 1575 MHz. 
     A number of compromises are typically made when designing an antenna for a handheld electronic device. For example, antennas that protrude excessively from a device housing may be unsightly. Antennas that are located within a device housing may be more desirable from an esthetic point of view, but can be challenging to design. Internal antennas are sometimes subject to proximity effects that make antenna performance dependent on the position of a user&#39;s body relative to the antenna. Moreover, internal antennas may require the use of compact designs that are not as efficient as bulky external antennas. 
     Compact internal antennas for handheld devices may fabricated by patterning a metal layer on a circuit board substrate or may be formed from a sheet of thin metal using a foil stamping process. Many handheld devices use planar inverted-F antennas (PIFAs). Planar inverted-F antennas are formed by locating a planar resonating element above a ground plane. These techniques can be used to produce antennas that fit within the tight confines of a handheld device. 
     Although compact antennas may be formed that are suitable for mounting within the interior of a handheld electronic device, such antennas may be subject to proximity effects. For example, if a user places their fingers over the antenna, the antenna may be detuned. This can cause undesirable dropped signals. 
     It would therefore be desirable to provide handheld electronic devices that can determine when antennas are blocked by a user&#39;s hand and can take appropriate actions. 
     SUMMARY 
     Handheld electronic devices and wireless communications circuitry for handheld electronic devices are provided. The wireless communications circuitry may include transceiver circuitry and one or more antennas. The transceiver circuitry may be used to transmit and receive radio-frequency signals through a coupler and an antenna. 
     A reflected power detection circuit may be connected to one port of the coupler. When signals are transmitted from the transceiver through the coupler and the antenna, a portion of the transmitted signals are reflected back from the antenna into the coupler. 
     When a user touches the handheld electronic device in the vicinity of the antenna, the antenna may be detuned due to proximity effects. This disrupts normal operation of the antenna and increases the amount of reflected signal power. 
     The coupler directs the reflected radio-frequency signals from the antenna into the reflected power detection circuit. The reflected power detection circuit may convert the reflected radio-frequency signals from the coupler into an analog reflected power signal. An analog to digital converter may be used to convert the analog reflected power signal into a digital reflected power signal. 
     Processing circuitry may be used to compare the reflected power signal to a threshold level. If the processing circuitry determines that the reflected power signal is relatively low, no action need be taken. If, however, the processing circuitry determines that the reflected power signal is relatively high, the processing circuitry can take appropriate action. 
     For example, the processing circuitry can issue an alert for the user of the handheld electronic device. The alert may be provided in visual form, in the form of an audio message, or as a vibrating alert. With one suitable arrangement, the handheld electronic device has a display on which a wireless signal strength indicator is displayed. When reflected power monitoring and control circuitry in the handheld electronic device determines that operation of the antenna is being disrupted due to proximity effects, an alert symbol may be displayed over the signal strength indicator. 
     If desired, the handheld electronic device may take other suitable actions when it is determined that antenna operation has been disrupted by proximity effects. For example, the handheld electronic device may chose to use a different (unblocked) antenna or may turn off portions of the device to save power. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative handheld electronic device with an antenna in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative handheld electronic device with an antenna in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an illustrative handheld electronic device with an antenna in accordance with an embodiment of the present invention. 
         FIGS. 4 ,  5 ,  6 ,  7 ,  8 , and  9  are views of the front of an illustrative handheld electronic device showing examples of suitable antenna resonating element positions within the device in accordance with embodiment of the present invention. 
         FIG. 10  is a schematic circuit diagram of monitoring and control circuitry in a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 11  is a schematic circuit diagram of illustrative control and monitoring circuitry that may be used to handle multiple antennas in a handheld electronic device in accordance with an embodiment of the present invention. 
         FIGS. 12 and 13  show how an illustrative signal strength warning indicator may be displayed for a user of a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 14  shows an illustrative signal strength warning message that may be displayed for a user of a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 15  is a flow chart of illustrative steps involved in using a handheld electronic device with wireless circuitry that includes antenna monitoring and control circuitry in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to wireless communications, and more particularly, to wireless electronic devices with reflected antenna signal monitoring capabilities. 
     The wireless electronic devices may be portable electronic devices such as laptop computers or small portable computers of the type that are sometimes referred to as ultraportables. Portable electronic devices may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. With one suitable arrangement, which is sometimes described herein as an example, the portable electronic devices are handheld electronic devices. 
     The handheld devices may be, for example, cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, global positioning system (GPS) devices, and handheld gaming devices. The handheld devices may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid handheld devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a handheld device that receives email, supports mobile telephone calls, has music player functionality and supports web browsing. These are merely illustrative examples. 
     An illustrative handheld electronic device in accordance with an embodiment of the present invention is shown in  FIG. 1 . Device  10  may be any suitable portable or handheld electronic device. 
     Device  10  may have housing  12 . Device  10  may include one or more antennas for handling wireless communications. 
     Device  10  may handle communications over one or more communications bands. For example, wireless communications circuitry in device  10  may be used to handle cellular telephone communications in one or more frequency bands and data communications in one or more communications bands. Typical data communications bands that may be handled by the wireless communications circuitry in device  10  include the 2.4 GHz band that is sometimes used for WiFi® and Bluetooth® communications, the 5 GHz band that is sometimes used for WiFi communications, the 1575 MHz Global Positioning System band, and 3G data bands (e.g., the UMTS band at 1920-2170). Each band may be handled by a separate antenna or one or more antennas may be used each of which handles one or more separate communications bands. 
     Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, glass, ceramics, metal, or other suitable materials, or a combination of these materials. In some situations, housing  12  or portions of housing  12  may be formed from a dielectric or other low-conductivity material, so that the operation of conductive antenna elements that are located in proximity to housing  12  is not disrupted by the housing. Housing  12  or portions of housing  12  may also be formed from conductive materials such as metal. An illustrative housing material that may be used is anodized aluminum. Aluminum is relatively light in weight and, when anodized, has an attractive insulating and scratch-resistant surface. If desired, other metals can be used for the housing of device  10 , such as stainless steel, magnesium, titanium, alloys of these metals and other metals, etc. In scenarios in which housing  12  is formed from metal elements, one or more of the metal elements may be used as part of the antenna in device  10 . For example, metal portions of housing  12  may be shorted to an internal ground plane in device  10  to create a larger ground plane element for that device  10 . To facilitate electrical contact between an anodized aluminum housing and other metal components in device  10 , portions of the anodized surface layer of the anodized aluminum housing may be selectively removed during the manufacturing process (e.g., by laser etching). 
     Housing  12  may have a bezel  14  that holds a display or other device with a planar surface in place on device  10 . The bezel  14  may be formed from a conductive material such as stainless steel. 
     Display  16  may be a liquid crystal diode (LCD) display, an organic light emitting diode (OLED) display, a plasma display, or any other suitable display. The outermost surface of display  16  may be formed from one or more plastic or glass layers. If desired, touch screen functionality may be integrated into display  16  or may be provided using a separate touch pad device. An advantage of integrating a touch screen into display  16  to make display  16  touch sensitive is that this type of arrangement can save space and reduce visual clutter. 
     In the example of  FIG. 1 , display screen  16  is shown as being mounted on the front face of handheld electronic device  10 , but display screen  16  may, if desired, be mounted on the rear face of handheld electronic device  10 , on a side of device  10 , on a flip-up portion of device  10  that is attached to a main body portion of device  10  by a hinge (for example), or using any other suitable mounting arrangement. 
     A touch sensitive display is merely one example of an input-output device that may be used with handheld electronic device  10 . If desired, handheld electronic device  10  may have other input-output devices. For example, handheld electronic device  10  may have user input control devices such as button  19 , and input-output components such as port  20  and one or more input-output jacks (e.g., for audio and/or video). Button  19  may be, for example, a menu button. Port  20  may contain a 30-pin data connector (as an example). Openings  24  and  22  may, if desired, form microphone and speaker ports. Audio output may be provided by a speaker located adjacent to a speaker port, by a buzzer or other tone generator, or any other suitable audio output device. A vibrating element may be used to produce vibrations that alert a user. Different patterns and types of vibrations may be used for different types of alerts. 
     A user of handheld device  10  may supply input commands using user input interface devices such as button  19  and touch screen  16 . Suitable user input interface devices for handheld electronic device  10  include buttons (e.g., alphanumeric keys, power on-off, power-on, power-off, and other specialized buttons, etc.), a touch pad, pointing stick, or other cursor control device, a microphone for supplying voice commands, or any other suitable interface for controlling device  10 . Although shown schematically as being formed on the front face of handheld electronic device  10  in the example of  FIG. 1 , buttons such as button  19  and other user input interface devices may generally be formed on any suitable portion of handheld electronic device  10 . For example, a button such as button  19  or other user interface control may be formed on the side of handheld electronic device  10 . Buttons and other user interface controls can also be located on the front face, rear face, or other portion of device  10 . If desired, device  10  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth remote control, etc.). 
     Handheld device  10  may have ports such as port  20 . Port  20 , which may sometimes be referred to as a dock connector, 30-pin data port connector, input-output port, or bus connector, may be used as an input-output port (e.g., when connecting device  10  to a mating dock connected to a computer or other electronic device). Device  10  may also have audio and video jacks that allow device  10  to interface with external components. Typical ports include power jacks to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data ports to exchange data with external components such as a personal computer or peripheral, audio-visual jacks to drive headphones, a monitor, or other external audio-video equipment, a subscriber identity module (SIM) card port to authorize cellular telephone service, a memory card slot, etc. The functions of some or all of these devices and the internal circuitry of handheld electronic device  10  can be controlled using input interface devices such as touch screen display  16 . 
     Components such as display  16  and other user input interface devices may cover most of the available surface area on the front face of device  10  (as shown in the example of  FIG. 1 ) or may occupy only a small portion of the front face of device  10 . Because electronic components such as display  16  often contain large amounts of metal (e.g., as radio-frequency shielding), it may be desirable to take the location of these components relative to the antenna elements into consideration. Suitably chosen locations for the antenna elements and electronic components of the device will allow the antennas of handheld electronic device  10  to function properly without being disrupted by the electronic components. 
     With one suitable arrangement, the antenna resonating element structures of device  10  are located in the lower end  18  of device  10 , in the proximity of port  20 . An advantage of locating antenna resonating element structures in the lower portion of housing  12  and device  10  is that this places radiating portions of the antenna structures away from the user&#39;s head when the device  10  is held to the head (e.g., when talking into a microphone and listening to a speaker in the handheld device as with a cellular telephone). In general, antenna(s) for device  10  may be located in any suitable portion of housing  12 . Placement of antenna structures in location  18  is merely illustrative. 
     A schematic diagram of an embodiment of an illustrative handheld electronic device is shown in  FIG. 2 . Handheld device  10  may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a remote control, a game player, a global positioning system (GPS) device, a combination of such devices, or any other suitable portable electronic device. 
     As shown in  FIG. 2 , handheld device  10  may include storage  34 . Storage  34  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
     Processing circuitry  36  may be used to control the operation of device  10 . Processing circuitry  36  may be based on a processor such as a microprocessor and other suitable integrated circuits. With one suitable arrangement, processing circuitry  36  and storage  34  are 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. Processing circuitry  36  and storage  34  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using processing circuitry  36  and storage  34  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, protocols for handling 3g data services such as UMTS, cellular telephone communications protocols, etc. 
     Input-output devices  38  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. Display screen  16 , button  19 , microphone port  24 , speaker port  22 , and dock connector port  20  are examples of input-output devices  38 . 
     Input-output devices  38  can include user input-output devices  40  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, tone generators, vibrating elements, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . Display and audio devices  42  may include liquid-crystal display (LCD) screens or other screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Device  10  can communicate with external devices such as accessories  46  and computing equipment  48 , as shown by paths  50 . Paths  50  may include wired and wireless paths. Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content). 
     Computing equipment  48  may be any suitable computer. With one suitable arrangement, computing equipment  48  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  10 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another handheld electronic device  10 ), or any other suitable computing equipment. 
     The antenna structures and wireless communications devices of device  10  may support communications over any suitable wireless communications bands. For example, wireless communications devices  44  may be used to cover communications frequency bands such as the cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, data service bands such as the 3 G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System), the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5.0 GHz (also sometimes referred to as wireless local area network or WLAN bands), the Bluetooth® band at 2.4 GHz, and the global positioning system (GPS) band at 1575 MHz. The 850 MHz band is sometimes referred to as the Global System for Mobile (GSM) communications band. The 900 MHz communications band is sometimes referred to as the Extended GSM (EGSM) band. The 1800 MHz band is sometimes referred to as the Digital Cellular System (DCS) band. The 1900 MHz band is sometimes referred to as the Personal Communications Service (PCS) band. 
     Device  10  can cover these communications bands and/or other suitable communications bands with proper configuration of the antenna structures in wireless communications circuitry  44 . 
     A cross-sectional view of an illustrative handheld electronic device is shown in  FIG. 3 . In the example of  FIG. 3 , device  10  has a housing that is formed of a conductive portion  12 - 1  and a plastic portion  12 - 2 . Conductive portion  12 - 1  may be any suitable conductor such as aluminum, magnesium, stainless steel, alloys of these metals and other metals, etc. 
     Housing portion  12 - 2  may be formed from a dielectric. An advantage of using dielectric for housing portion  12 - 2  is that this allows a resonating element portion  54 - 1  of antenna  54  of device  10  to operate without interference from the metal sidewalls of housing  12 . With one suitable arrangement, housing portion  12 - 2  is a plastic cap formed from a plastic based on acrylonitrile-butadiene-styrene copolymers (sometimes referred to as ABS plastic). These are merely illustrative housing materials for device  10 . For example, the housing of device  10  may be formed substantially from plastic or other dielectrics, substantially from metal or other conductors, or from any other suitable materials or combinations of materials. Antenna resonating element  54 - 1  may be formed using any suitable antenna resonating element structure (e.g., a strip of conductor that forms a monopole antenna, a planar inverted-F resonating element structure, structures with multiple antenna resonating element branches, etc.). 
     Components such as components  52  may be mounted on circuit boards in device  10 . The circuit board structures in device  10  may be formed from any suitable materials. Suitable circuit board materials include paper impregnated with phonolic resin, resins reinforced with glass fibers such as fiberglass mat impregnated with epoxy resin (sometimes referred to as FR-4), plastics, polytetrafluoroethylene, polystyrene, polyimide, and ceramics. Circuit boards fabricated from materials such as FR-4 are commonly available, are not cost-prohibitive, and can be fabricated with multiple layers of metal (e.g., four layers). So-called flex circuits, which are flexible circuit board materials such as polyimide, may also be used in device  10 . 
     Typical components in device  10  include integrated circuits, LCD screens, and user input interface buttons. Device  10  also typically includes a battery, which may be mounted along the rear face of housing  12  (as an example). 
     Because of the conductive nature of components such as these and the printed circuit boards upon which these components are mounted, the components, circuit boards, and conductive housing portions including optional bezel  14  of device  10  may be grounded together to form an antenna ground plane  54 - 2 . With one illustrative arrangement, ground plane  54 - 2  may conform to the generally rectangular shape of housing  12  and device  10  and may match the rectangular lateral dimensions of housing  12 . 
     Ground plane element  54 - 2  and antenna resonating element  54 - 1  form antenna  54  for device  10 . If desired, other antennas can be provided for device  10  in addition to antenna  54  of  FIG. 3 . Such additional antennas may, if desired, be configured to provide additional gain for an overlapping frequency band of interest (i.e., a band at which antenna  54  is operating) or may be used to provide coverage in a different frequency band of interest (i.e., a band outside of the range of antenna  54 ). 
     Any suitable conductive materials may be used to form ground plane element  54 - 2  and resonating element  54 - 1  in antenna  54 . Examples of suitable conductive materials for antenna  54  include metals, such as copper, brass, silver, and gold. Conductors other than metals may also be used, if desired. In a typical scenario, the conductive structures for resonating element  54 - 1  are formed from copper traces on a flex circuit or other suitable substrate. 
     Components  52  include transceiver circuitry (see, e.g., devices  44  of  FIG. 2 ). The transceiver circuitry may be provided in the form of one or more integrated circuits and associated discrete components (e.g., filtering components). Transceiver circuitry may include one or more transmitter integrated circuits, one or more receiver integrated circuits, switching circuitry, amplifiers, etc. Each transceiver in transceiver circuitry may have an associated coaxial cable or other transmission line that is connected to antenna  54  and over which radio frequency signals are conveyed. In the example of  FIG. 3 , a transmission line is depicted by dashed line  56 . 
     As shown in  FIG. 3 , transmission line  56  may be used to distribute radio-frequency signals that are to be transmitted through an antenna such as antenna  54  from a transmitter integrated circuit and other suitable wireless circuitry to the antenna. Paths such as path  56  may also be used to convey radio-frequency signals that have been received by an antenna such as antenna  54  to components  52 . A receiver integrated circuit or other transceiver circuitry may be used to process incoming radio-frequency signals that have been conveyed from an antenna over one or more transmission lines. 
     In the example of  FIG. 3 , antenna  54  is located at the lower end of device  10 . This is merely illustrative. Examples of antenna arrangements in which antennas are formed at different locations within a device are shown in the top (front) views of  FIGS. 4 ,  5 ,  6 ,  7 ,  8 , and  9 . In these examples, device  10  is shown in a portrait orientation. If desired, device  10  may be used in a landscape orientation (rotated 90° relative to the portrait orientation) or may be used in both portrait and landscape orientations (e.g., in different modes of operation). 
       FIG. 4  shows an example in which antennas  54 A and  54 B are formed at opposite ends of device  10 . Antennas  54 A and  54 B may be located at the top and bottom of device  10  when viewing its display  16  in a portrait orientation (as an example). 
     The illustrative arrangement of  FIG. 5  shows how antenna  54  may be located at the top of device  10 . 
     Antenna  54  may have any suitable size or shape. For example, antenna  54  may be compact enough to be located in a corner of device  10 . As shown in  FIG. 6 , antenna  54  may be located in the upper right corner of device  10 . 
     In the example of  FIG. 7 , there are two antennas of different sizes. Antenna  54 A extends across the width of the lower portion of device  10 . Antenna  54 B is located in the upper right corner of device  10 . 
     As shown in  FIG. 8 , there may be more than two antennas in device  10 . These antennas may be located at different corners or ends of device  10  to minimize interference with each other. In the example of  FIG. 8 , antenna  54 A extends across substantially all of the width of device  10 , whereas antennas  54 B and  54 C are compact enough to be located in different corners of device  10 . If desired, multiple antennas in device  10  may be located adjacent to each other. 
     An example in which there are four antennas in device  10  is shown in  FIG. 9 . In the example of  FIG. 9 , antenna  54 A is located in the lower left corner, antenna  54 B is located in the lower right corner, antenna  54 C is located in the upper left corner, and antenna  54 D is located in the upper right corner. 
     In embodiments of device  10  that have multiple antennas (e.g., embodiments such as the embodiments of  FIGS. 4 ,  7 ,  8 , and  9  or other suitable multiple antenna arrangements), the multiple antennas may be used to expand the frequency coverage of device  10 . For example, an antenna may be used to provide frequency coverage for a communications band that would not otherwise be covered by the other antennas in device  10 . Additional antenna structures may also be used to provide more sensitivity for an existing band. For example, device  10  may have an antenna that provides expanded coverage by overlapping and reinforcing an existing frequency band o interest. 
     If desired, multiple antennas may be used to provide redundancy. For example, two or more antennas in device  10  may be used to implement an antenna diversity arrangement. In this type of scheme, multiple antennas are used to cover the same communications band. If a given one of the antennas is performing poorly, the handheld electronic device may automatically detect this condition and may switch to another antenna that is covering the same band. 
     In some handheld device arrangements, it may be desired to minimize the amount of space consumed by antenna structures. In these configurations, it may be desirable to minimize the use of redundant antennas. 
     Handheld electronic devices such as device  10  are often touched by a user. For example, a device  10  may be held in the hand of a user and placed against the side of a user&#39;s head when the user is making a cellular telephone call. As another example, a user may hold either end of device  10  in the user&#39;s fingers when the user is operating device  10  in a landscape orientation. In other situations, the user may hold or touch device  10  using other parts of the body. The user may also place device  10  adjacent to metal objects (e.g., when placing device  10  on a countertop, etc.). 
     In each of these environments, there is a potential for one or more of the antennas to become partially or completely blocked. For example, incoming and outgoing radio-frequency communications may be disrupted because the user&#39;s hand or other body part or other items are placed in close proximity to the antenna. This may detune the antenna by causing its resonance peak to shift away from its desired frequency or may otherwise disrupt antenna operations. Antenna disruptions that are caused by the user placing a body part or other item in the vicinity of the antenna are sometimes referred to as being caused by proximity effects. 
     Antenna blockages can cause difficulties for a user of a handheld electronic device. For example, if a user holds the device in an inappropriate fashion or places the device in an environment in which proper antenna operations are disrupted, a cellular telephone call may be disrupted or a data transfer operation may be disrupted. 
     To avoid problems such as these, handheld electronic device  10  may be provided with monitoring and control circuitry that monitors the antennas in the device. If it is determined that wireless signals are not being handled properly, suitable actions may be taken. 
     For example, the user of a device may be warned that one or more of the antennas in the device is not operating properly. The warning may be provided using an audio alert (e.g., a warning tone or audio clip warning), a visual alert (e.g., by lighting an indicator, by displaying a textual or symbolic warning message for the user, etc.), by touch (e.g., by turning on a vibrating element within the device), using other suitable input-output arrangements, or by using a combination of such approaches. 
     The wireless circuitry of device  10  may also switch to a different antenna (i.e., when multiple antennas are available that can communicate in the communications band of interest), may adjust the transmitted signal power, may adjust the input gain, etc. 
     Combinations of alert message actions and antenna adjustment actions may also be taken. 
     Any suitable antenna monitoring and control circuitry arrangement may be used in device  10 . For example, incoming signal strength can be monitored by analyzing incoming data (e.g., to determine how many data errors are present or to otherwise ascertain the quality of the signal). 
     With one particularly suitable arrangement, which is described herein as an example, device  10  may use a radio-frequency signal coupler to monitor the amount of outgoing signal power that is reflected back from the antenna. When there is no significant antenna blockage, signals will be transmitted efficiently and the amount of reflected power will be low. In this situation, device  10  can be operated normally. When a user places a body part or other object in close proximity to an antenna, the normal operation of the antenna may be disrupted due to proximity effects. When antenna operations are disrupted due to proximity effects, radio-frequency signals will not be transmitted efficiently and the amount of signal power that is reflected from the antenna will increase. Because observations of high levels of reflected signal power are indicative of antenna blockage, the user can be warned that the antenna is being blocked or other suitable actions can be taken. 
     Illustrative monitoring and control circuitry  60  that may be used in device  10  is shown in  FIG. 10 . Transceiver circuitry such as transceiver circuitry  82  may be used to transmit and receive radio-frequency communications signals. Transceiver circuitry  82  may be based on one or more transceiver integrated circuits. Outgoing signals for antenna  54  may be transmitted through transmit port TX. Incoming signals from antenna  54  may be received at receive port RX. 
     Transceiver circuitry  82  may be coupled to antenna  54  using any suitable arrangement. As shown in the illustrative configuration of  FIG. 10 , a switch such as switch  64  may be used to selectively connect transceiver circuitry  82  to antenna  54  through radio-frequency filter  62 . Filter  62  may be, for example, a bandpass filter. 
     The state of switch  64  may be controlled by control signals generated by transceiver circuitry  82  or other control logic. When it is desired to receive signals from antenna  54 , switch  64  may be placed in position A. In position A, signals that are received from antenna  54  are directed to the RX port of transceiver circuitry  82  via path  66 . When it is desired to transmit signals through antenna  54 , switching circuitry  64  may be placed in position B. In this configuration, signals from the TX port of transceiver circuitry  82  are routed to antenna  54  through power amplifier  76 , coupler  70 , and switch  64 . 
     Power detection circuit  74  may be used to detect reflected power from antenna  74 . In the example of  FIG. 10 , power detection circuit  74  is formed using a diode that converts reflected radio-frequency signals into a direct current (DC) analog signal that may be digitized by analog to digital converter  78  of transceiver circuitry  82 . This is, however, merely illustrative. Any suitable detection circuitry may be used to monitor reflected radio-frequency signal power if desired. 
     Coupler  70  may have four ports. A first port may be connected to the TX port of transceiver circuitry  82  via path  88  and power amplifier  76 . A second port may be coupled to switch terminal B via path  68 . A third port may be coupled to power detection circuit  74  using path  90 . A fourth port may be coupled to termination resistor R and ground terminal  72  via path  92 . 
     During operation of the transmitter circuitry in transceiver circuitry  82 , a fraction of the transmitted signal power is reflected back from antenna  54  into coupler  70 . As shown by dotted line  94 , these reflected signals are directed to power detection circuit  74  through the third port of coupler  70 . 
     Although shown separately in  FIG. 10 , components such as transceiver circuitry  82 , power amplifier  76 , coupler  70 , switch  64 , filter  62 , and antenna  54  can be implemented using integrated components, if desired. For example, components such as reflected signal power detection circuit  74 , coupler  70 , and switch  64  may be provided using one or more integrated devices. 
     Transceiver circuitry  82  may have a processor such as processor  80  that receives digital signals from analog to digital converter circuit  78 . The output of power monitoring circuit  74  may be an analog signal that represents the amount of power that has been reflected back from antenna  54  during data transmission operations. Analog to digital converter  78  may be used to digitize this monitored reflected power level. Processor  80  may be used to digitally process the digital signal data. Processor  80  may, if desired, analyze the reflected signal data to determine when the operation of antenna  54  has been disrupted. When operation has been disrupted, processor  80  may determine a suitable course of action. 
     If desired, processor  80  may work in conjunction with additional processing circuitry in device  10 . As shown  FIG. 10 , for example, processor  80  may communicate with an external processor such as processor  86  via path  84 . Path  84  may be any suitable data communications path (e.g., serial data path, a parallel data path, a path involving a single conductive line, a path involving parallel data lines, etc.). Processor  86  may be, for example, the main microprocessor contained in handheld electronic device  10 . Processing circuitry such as processor  80  and/or processor  86  may be used to monitor the measured reflected power from detector circuit  74  and may be used to control the operation of device  10 . 
     Processing circuitry such as processors  80  and  86  may analyze the reflected power signal by comparing the measured signal to a threshold or performing other suitable processing operations. There may be one threshold associated with the monitored reflected power so that the reflected power may be characterized as being high or low, or there may be multiple thresholds or ranges that are associated with the measured reflected power. More complex comparisons (e.g., comparisons involving the current state of device  10  or trend information) may also be made. These are merely illustrative examples. Any suitable type of signal analysis may be performed on the measured reflected antenna signal power if desired. 
     In a typical scenario, which is sometimes described herein as an example, reflected signals that are below a given threshold are characterized as being “low” or “normal,” whereas signals that are above the given threshold are characterized as being “high” or “abnormal.” With this type of arrangement, device  10  can conclude that normal antenna operation has been achieved whenever the amount of signal that is reflected from the antenna during transmission operations is below the threshold. Whenever the reflected signal exceeds the threshold, device  10  can conclude that normal antenna operation has been disrupted due to proximity effects and can take appropriate actions. 
     As shown in  FIG. 10 , processor  86  may communicate with input-output devices  38 . Processing circuitry such as processor  80  and/or processor  86  may be used to control devices such as devices  38  to take appropriate actions when a high amount of reflected power is detected from detection circuit  74 . For example, processor  86  may use I/O devices  38  to issue alerts. Alert messages and other suitable messages may be presented to users using a display, a vibrating device, an audio device (e.g., a speaker or a tone generator), a light emitting diode or other indicator lights, etc. 
     If desired, processing circuitry such as processor  80  and/or processor  86  may take other suitable actions when a high amount of reflected power is detected. For example, the processing circuitry may assume that the high amount of reflected power is indicative of such poor antenna performance that transceiver circuitry  82  should be shut off to conserve power. As another example, the processing circuitry may assume that a user has picked up device  10 . In this scenario, the reflected power signal monitoring circuitry is being used to form a touch sensor. Other suitable actions include increasing output power to compensate for antenna detuning (e.g., by increasing the gain of power amplifier  76 ) or increasing receiver sensitivity (e.g., by increasing the gain of an amplifier in the input path). 
     When redundant antenna circuitry is available, the processing circuitry on device  10  may switch between different antennas. An arrangement in which device  10  has monitoring and control circuitry  60  that handles multiple redundant antennas  54  is shown in  FIG. 11 . In this type of configuration, each antenna  54  may cover the same communications band, but may be mounted in a different portion of the housing of device  10  to implement an antenna diversity scheme. If the processing circuitry that is associated with one antenna is disrupted, transceiver circuitry  82  may use a different antenna  54  to transmit and receive signals. As shown in  FIG. 11 , each antenna  54  may have an associated reflected power detection circuit  74 . Components such as power amplifiers  76  may be provided for each redundant antenna  54  (as shown in the  FIG. 11  example) or may be shared using switching circuitry. 
     Device  10  may display a signal strength indicator for a user such as signal strength indicator  96  of  FIG. 12 . Signal strength indicators such as these may use lines, bars, numbers, or other suitable visual representations to indicate to a user the status of the current communications link between device  10  and the equipment with which device  10  is communicating. The link strength may, as an example, be derived from received signal error rate or power measurements. The signal strength may vary between zero (no signal) to a fixed value (e.g., “five bars”). 
     As shown in  FIG. 13 , when monitoring and control circuitry  60  detects that the reflected signal power is high, the processing circuitry of device  10  may use display  16  to display a blocked antenna indicator such as indicator  98 . In the example of  FIG. 13 , indicator  98  has been provided in the form of a hand that is displayed over signal strength indicator  96 . This visually indicates to the user that antenna operation is being disrupted by the presence of the user&#39;s hand or other body part. The user can remedy the situation by changing the way in which device  10  is being held. As soon as the antenna  54  is no longer being blocked by the user&#39;s touch, the visual warning provided by indicator  98  may be removed. 
     As shown in  FIG. 14 , an antenna blockage warning may be displayed in the form of a text alert on display  16 . When a user reads message  100 , the user is informed that the user&#39;s hand is covering the antenna. The user may take corrective action by holding device  10  in such a way that antenna operation is not disrupted. As soon as the monitored reflected antenna power reading drops below the threshold level, warning  100  may be removed. If desired, a confirmatory message may be displayed such as “antenna is working properly.” 
     Illustrative steps involved in monitoring antenna performance and taking associated actions are shown in  FIG. 15 . At step  102 , a user of device  10  may use antenna(s)  54  to transmit and receive wireless radio-frequency signals. The signals may be associated with cellular telephone calls, incoming GPS signals, data signals for WiFi networks or Bluetooth links, long range data signals using data links such as 3 G communications links, etc. 
     During normal operation of device  10 , the antenna structures (e.g., the antenna resonating elements) of device  10  should not be blocked by a user. If an antenna structure is covered by a user&#39;s hand or is otherwise touched or obstructed by a body part of the user or by another item, antenna performance may be degraded due to proximity effects. When antenna performance is disrupted in this way, the antenna becomes detuned from its desired operating frequency. As a result, the amount of transmitted power that is reflected back through coupler  70  to power detection circuitry  74  is increased. The processing circuitry in device  10  can measure the amount of transmitted signal that is reflected back from antenna  54  to determine whether the antenna is operating properly. If the amount of reflected power is within normal operating limits, device  10  can conclude that the reflected signal power level is acceptable and can continue monitoring the reflected signal power without taking further actions (see, e.g., line  104  in  FIG. 15 ). 
     If the amount of reflected power that is detected by the monitoring circuitry exceeds a user-defined or default threshold value or if device  10  otherwise concludes that the amount of reflected power is not appropriate, device  10  can take appropriate actions at step  106 . 
     In general, any suitable actions or combinations of actions may be taken when a high amount of reflected power is detected at step  102 . For example, a user may be alerted using a visual indicator (e.g., the warning image of  FIG. 13 ). The user may also be alerted using other visual arrangements. The user may, as an example, be alerted by flashing a light emitting diode, by displaying a text message as described in connection with  FIG. 14 , by flashing the entire display or a portion of the display, by vibrating device  10  using a vibrating element, by issuing an audio alert in the form of a chime, bell, or other tone, by playing an audio clip (e.g., a warning clip), by using other suitable alerting schemes or a combination of these arrangements. 
     Other suitable corrective actions that may be taken include adjusting the input or output gain, switching to an antenna that is not blocked, shutting down transceiver circuitry  82  and/or other wireless communications circuitry to conserve power, locking device  10  (e.g., when using the reflected power feature as a touch sensor), otherwise changing the operation of device  10 , etc. 
     Reflected power monitoring arrangements can be used in conjunction with other signal monitoring arrangements to improve accuracy or add functionality to device  10 . For example, received signal strength can be monitored by evaluating the quality of the incoming signal (e.g., by evaluating its error rate, signal to noise ratio, power, etc.), while also measuring the amount of power that is reflected back from antenna  54  during signal transmission operations to assess whether the antenna is being adversely affected by proximity effects. 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20071010
Publication Date: 20141118
Grant Date: 20141118
Priority Date: 20071010
Inventors: ROSENBLATT MICHAEL N.
SANGUINETTI LOUIE J.
KOCALAR ERTURK D.
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/242", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/242", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 40533681