Patent Grant
7551142
This invention relates generally to wireless communications circuitry, and more particularly, to wireless communications circuitry for handheld electronic devices.
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 Wi-Fi® (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 3G data communications band at 2170 MHz (commonly referred to as the UMTS or Universal Mobile Telecommunications System band). Handheld devices with Global Positioning System (GPS) capabilities receive GPS signals at 1575 MHz.
To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to reduce the size of components that are used in these devices. For example, manufacturers have made attempts to miniaturize the antennas used in handheld electronic devices.
A typical antenna may be 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. Antennas such as planar inverted-F antennas (PIFAs) and antennas based on L-shaped resonating elements can be fabricated in this way. Antennas such as PIFA antennas and antennas with L-shaped resonating elements can be used in handheld devices.
Although modern handheld electronic devices often need to function over fairly wide frequency bands or over a number of different communications bands, it is difficult to design a compact antenna that covers all frequencies of interest while satisfying design constraints related to antenna efficiency and immunity to proximity effects.
It would therefore be desirable to be able to provide improved antennas and wireless handheld electronic devices.
Handheld electronic devices and antennas for handheld electronic devices are provided. A handheld electronic device may have conductive structures that form an antenna ground plane element. The ground plane element may have portions that define a slot antenna resonating element. Another antenna resonating element may be electromagnetically coupled to the slot antenna resonating element through electromagnetic near-field coupling. During operation, a coaxial cable or other transmission line in a handheld electronic device may directly feed the slot antenna resonating element and may indirectly feed the near-field-coupled antenna resonating element through the slot antenna resonating element.
The slot antenna resonating element may have multiple openings or branches that define multiple associated inner slot perimeters and thereby allow the slot antenna resonating element to resonate at multiple resonant frequencies. The near-field-coupled antenna resonating element may have multiple branches that allow the near-field-coupled antenna resonating element to resonate at multiple frequencies. The resonant peaks associated with the slot antenna resonating element portion of the antenna and the near-field-coupled antenna resonating element portion of the antenna can be configured to nearly or exactly coincide with each other to broadened the bandwidth of a given communications band or can be configured to provide coverage for distinct communications bands. In some configurations, the use of more than one antenna resonating element to transmit and receive radio-frequency signals for a handheld electronic device may make the antenna and handheld electronic device less susceptible to influences from a user's hand position.
A handheld electronic device may have a conductive housing and a conductive bezel. The conductive housing and conductive bezel may be used in defining the shape of the slot antenna resonating element. The slot antenna resonating element may be approximately rectangular in shape and may have a longitudinal axis. Non-rectangular shapes may also be used for the slot. The near-field-coupled antenna resonating element may have a portion that runs parallel to the longitudinal axis of the slot antenna resonating element and may have portions that run perpendicular to the longitudinal axis of the slot antenna resonating element while remaining parallel to a planar ground plane element.
The antenna may be provided with electrical components such as inductors and capacitors. For example, a capacitor may be placed across the slot antenna resonating element or may be used to terminate one end of the near-field-coupled resonating element to ground. An inductor may be incorporated at one end of the near-field-coupled resonating element or may be placed across the antenna feed terminals.
The near-field-coupled antenna resonating element may be formed from wires or other lengths of conductor or may contain planar portions that lie parallel to planar portions of the antenna's ground plane. For example, the near-field-coupled antenna resonating element may have planar conductive portions with multiple branches or serpentine paths that lie parallel to a planar ground plane element. The ground plane of the handheld electronic device may include planar elements such as a conductive housing or a printed circuit board ground conductor.
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.
The present invention relates generally to wireless communications, and more particularly, to wireless electronic devices and antennas for wireless electronic devices.
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 devices of these types. 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
Device 10 may have housing 12 and may include one or more antennas for handling wireless communications. Device 10 may handle communications over multiple 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. With one suitable arrangement, which is sometimes described herein as an example, the wireless communications circuitry of device 10 may use a first antenna that is configured to handle communications in one or more communications bands and may use a second antenna that is configured to handle communications in one or more additional communications band. The first antenna may, for example, handle communications in a communications band that is centered at 2.4 GHz (e.g., Wi-Fi and/or Bluetooth frequencies) while simultaneously receiving Global Positioning Systems (GPS) communications at 1575 MHz. The second antenna may handle cellular telephone communications bands and/or 3G data communications bands such as the Universal Mobile Telecommunications System (UMTS) 3G data communications band at 2170 MHz (as examples).
Housing 12, which is sometimes referred to as a case, may be formed of any suitable materials including plastic, glass, ceramics, metal, 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. 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. The bezel 14 may be formed from a conductive material. The conductive material may be a metal (e.g., an elemental metal or an alloy) or other suitable conductive materials. With one suitable arrangement, which is sometimes described herein as an example, bezel 14 may be formed from stainless steel. Stainless steel can be manufactured so that it has an attractive shiny appearance, is structurally strong, and does not corrode easily. If desired, other structures may be used to form bezel 14. For example, bezel 14 may be formed from plastic that is coated with a shiny coating of metal or other suitable substances.
Bezel 14 may serve to hold a display or other device with a planar surface in place on device 10. As shown in
Display 16 may be a liquid crystal diode (LCD) display, an organic light emitting diode (OLED) 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 a typical arrangement, bezel 14 may have prongs that are used to secure bezel 14 to housing 12 and that are used to electrically connect bezel 14 to housing 12 and other conductive elements in device 10. The housing and other conductive elements form a ground plane for the antenna(s) in the handheld electronic device. A gasket (e.g., an o-ring formed from silicone or other compliant material, a polyester film gasket, etc.) may be placed between the underside of bezel 14 and the outermost surface of display 16. The gasket may help to relieve pressure from localized pressure points that might otherwise place stress on the glass or plastic cover of display 16. The gasket may also help to visually hide portions of the interior of device 10 and may help to prevent debris from entering device 10.
In addition to serving as a retaining structure for display 16, bezel 14 may serve as a rigid frame for device 10. In this capacity, bezel 14 may enhance the structural integrity of device 10. For example, bezel 14 may make device 10 more rigid along its length than would be possible if no bezel were used. Bezel 14 may also be used to improve the appearance of device 10. In configurations such as the one shown in
Display screen 16 (e.g., a touch screen) 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. Display screen 16 may be, for example, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a plasma display, or multiple displays that use one or more different display technologies. In the example of
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 as being formed on the top face of handheld electronic device 10 in the example of
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
Handheld electronic device 10 may have one or more antennas. For example, handheld electronic device may have a first antenna that is located in the upper end of device 10 in region 21 and a second antenna that is located in the lower end of device 10 in region 18. Additional antennas or only a single antenna may be used in device 10 if desired.
In an illustrative arrangement with two antennas, the first antenna may be a multiband antenna that covers two or more frequency bands of interest such as the Wi-Fi/Bluetooth band at 2.4 GHz and the GPS band at 1575 MHz and the second antenna may be used to cover bands such as cellular telephone bands, data bands (e.g., 3G data bands), etc. An advantage of locating the first and second antennas at opposite ends of device 10 is that this separates the antennas from each other and helps to reduce the possibility of radio-frequency interference.
A schematic diagram of an embodiment of an illustrative handheld electronic device is shown in
As shown in
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 Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, protocols for handling 3G data services such as UMTS, Global Positioning System (GPS) protocols, 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, 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'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 3G data communications band at 2170 MHz (commonly referred to as the UMTS or Universal Mobile Telecommunications System band), the Wi-Fi® (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
There are two antennas in the example of
Resonating element 54-1B in antenna 54 may be formed from an elongated resonating element structure such as an L-shaped strip or arm (branch). Multibranch structures and structures with planar portions may be used for resonating element 54-1B if desired. Resonating element 54-1B may be formed from any suitable conductive structure such as a length of wire, a strip of metal foil or other conductor, or traces on a flex circuit, etc.
An advantage of using dielectric for housing portions 12-2A and 12-2B is that this allows the antennas of device 10 to operate without interference from the metal sidewalls of housing 12. With one suitable arrangement, housing portions 12-2A and 12-2B may be plastic caps 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.
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 bezel 14) of device 10 may be grounded together to form 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.
Any suitable conductive materials may be used to form ground plane element 54-2 and resonating elements 54-1A and 54-1B. Examples of suitable conductive materials for the antenna structures in device 10 include elemental metals, such as copper, silver, and gold, and metal alloys (e.g., beryllium copper). Conductors other than metals may also be used, if desired.
Components 52 may include transceiver circuitry (see, e.g., devices 44 of
Transmission lines 56 may be used to distribute radio-frequency signals that are to be transmitted through the antennas from a transmitter integrated circuit 52. Paths 56 may also be used to convey radio-frequency signals that have been received by an antenna to components 52. Components 52 may include one or more receiver integrated circuits for processing incoming radio-frequency signals.
As shown in the cross-sectional diagram of
Part of the frequency response of antenna 54 may be obtained by forming an opening within ground plane 54-2 that resonates in a desired frequency band (e.g., the lower frequency band in a two-band arrangement). The opening, which is sometimes referred to as a slot, may have any suitable shape. For example, the slot may be rectangular, the slot may have curved sides, the slot may have any suitable number of straight sides, the slot may have a combination of straight sides and curved sides, etc.
In operation, the portion of antenna 54 that contains the slot forms a slot antenna. The slot antenna structure in antenna 54 can be used at the same time as a non-slot antenna resonating element (e.g., an L-shaped strip). In particular, antenna performance can be improved when operating antenna 54 as a hybrid device in which both its non-slot antenna resonating element operating characteristics and its slot antenna resonating element operating characteristics are present. In hybrid operation, the slot antenna portion of the antenna may provide a frequency response in a lower frequency communications band, whereas the L-shaped arm (or other non-slot portion) portion of the antenna may provide a frequency response in a higher frequency communications band (as an example).
A top view of an illustrative slot antenna is shown in
Coaxial cable 56 or any other suitable transmission line may be used to feed antenna 72. In the example of
When the slot antenna resonating element of antenna 72 is directly fed using an arrangement of the type shown in
In the illustrative arrangement of
An arrangement in which slot 70 has a non-rectangular shape is shown in
The shape of slot 70 may be defined by the shape of an opening in planar ground plane elements such as a printed circuit board or other mounting structure. The shape of slot 70 may also be defined by the layout of conductive components within device 10. For example, on end of a rectangular slot may be defined by the presence of a component with metal parts.
With one suitable arrangement, the shape of slot 70 is defined by an opening that is formed by bezel 14 and the printed circuit board structures, planar housing surfaces, and conductive components 52 in device 10 that form ground plane 54-2. An illustrative arrangement of this type is shown in
Any suitable feed arrangement may be used to feed antenna 54. With one suitable arrangement, which is described herein as an example, the slot antenna resonating element of antenna 54 is directly fed (e.g., using antenna feed terminals such as positive antenna terminal 80 or 84 of
In a direct feeding arrangement for the slot of antenna 54, a ground conductor in a coaxial cable or other transmission line 56 may be coupled to an antenna ground terminal on one portion of the slot's periphery while a center or positive conductor in a coaxial cable or other transmission line 56 may be coupled to a positive antenna terminal on another portion of the slot's periphery. The ground and positive antenna terminals may, for example, be located on opposite sides of a slot that has a rectangular portion as shown in
With an indirect feed arrangement, the non-slot resonating element is coupled to the slot resonating element by near-field electromagnetic coupling, rather than being directly fed through the positive and ground antenna terminals. Due to this near-field electromagnetic interaction, transmitted signals from the transmission line can be coupled onto the non-slot resonating element by way of the directly fed slot resonating element. Similarly, signals can be received using the non-slot resonating element because the non-slot resonating element is near-field coupled to the slot antenna resonating element that is directly coupled to the transmission line.
By proper selection of the resonant frequencies for the directly fed slot antenna resonating element and the indirectly fed antenna resonating element, a desired amount of frequency coverage for antenna 54 may be obtained.
An illustrative antenna having a slot antenna resonating element that is directly fed and a non-slot antenna resonating element that is indirectly fed is shown in
In antenna 54 of
Slot resonating element 70 may have an antenna resonance at a frequency that is determined by its inner perimeter P, as described in connection with
As shown in
As shown in
If the resonant frequencies are configured to be the same (i.e., if slot 70 and element 54-1B are configured so that f1 equals f2), the resonant peak associated with slot 70 will coincide with the resonant peak associated with element 54-1B. This may improve antenna performance at or near the resonant frequency. For example, antenna 54 may exhibit improved immunity to the position of a user's hand on device 10 when compared to an antenna that does not contain both slot 70 and element 54-1B. Providing immunity to proximity effects in this way may make the wireless performance of device 10 more robust.
If the resonant frequencies are configured to be slightly different, one resonating element will cover a lower portion of the communications band, whereas the other resonating element will cover an upper portion of the communications band. This type of arrangement, which is depicted in
Another suitable arrangement is shown in
It is not necessary for resonating element 54-1B to be placed on one side of slot 70 as shown in the illustrative arrangement of
Another suitable arrangement is shown in
With the illustrative configuration of
As shown in
The illustrative antenna arrangements of
If desired, antenna 54 may be formed from a directly fed slot and an indirectly fed planar antenna resonating element. An illustrative antenna configuration of this type is shown in
Planar portion 122 may be parallel to ground plane 54-2. A vertical conductive structure such as planar conductive structure 120 may be used to connect planar structure 122 to ground plane 54-2. If desired, other conductive structures may be used to connect planar antenna structures in resonating element 54-1B to ground plane 54-2. For example, wires, strips of conductor, multiple vertical planar elements, or other suitable conductors may be used to connect planar antenna portion 122 to ground.
The electrical properties of planar structures such as planar antenna resonating element 54-1B may differ from those of substantially non-planar structures (e.g., those based on L-shaped wires or narrow traces on a flex circuit). For example, planar structures of the type shown in antenna resonating element 54-1B of
If desired, other planar shapes may be used for antenna resonating element 54-1B. For example, planar portion 122 of antenna resonating element 54-1B may be implemented using a planar conductor that is configured to form a serpentine path as shown in
If desired, planar antenna resonating elements may be provided with multiple branches (arms). An illustrative arrangement in which planar portion 122 of antenna resonating element 54-1B has two branches is shown in
As shown in
If desired, electrical components may be used to adjust the feed characteristics of antenna 52. For example, an inductor such as inductor 135 may be connected between the ground and positive antenna terminals 78 and 80 (e.g., for impedance matching to transmission line 56), as shown in
As shown in
If desired, antenna 54 can be tuned by connecting electrical components to antenna resonating element 54-1B. For example, an inductor such as inductor 140 may be placed in vertical path portion 142 (or other suitable location) within antenna resonating element 54-1B as shown in
As shown in
If desired, slot antenna resonating element 70 may be provided with multiple portions each of which has a different associated resonant frequency. As shown in
Another example is shown in
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.
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