Patent Application
20140333495
This relates generally to electronic devices, and more particularly, to antennas for electronic devices with wireless communications circuitry.
Electronic devices such as portable computers and cellular telephones are often provided with wireless communications capabilities. For example, electronic devices may use long-range wireless communications circuitry such as cellular telephone circuitry to communicate using cellular telephone bands. Electronic devices may use short-range wireless communications circuitry such as wireless local area network communications circuitry to handle communications with nearby equipment. Electronic devices may also be provided with satellite navigation system receivers and other wireless circuitry.
To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to implement wireless communications circuitry such as antenna components using compact structures. At the same time, it may be desirable to include conductive structures in an electronic device such as metal device housing components. Because conductive structures can affect radio-frequency performance, care must be taken when incorporating antennas into an electronic device that includes conductive structures. Moreover, care must be taken to ensure that the antennas and wireless circuitry in a device are able to exhibit satisfactory performance over a range of operating frequencies.
It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless electronic devices.
Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antennas. An antenna may be formed from an antenna resonating element and an antenna ground.
The antenna resonating element may have a longer portion that resonates at first communications band frequencies and a shorter portion that resonates at second communications band frequencies above the first communications band frequencies. The resonating element may be formed from peripheral conductive electronic device housing structures that are separated from the antenna ground by an opening.
An extended portion of the antenna ground may form an inverted-F antenna resonating element portion of the antenna resonating element that resonates at third communications band frequencies above the first and second communications band frequencies.
A first antenna feed may be coupled between the peripheral conductive electronic device housing structures and the antenna ground across the opening. A second antenna feed may be coupled to the inverted-F antenna resonating element portion of the antenna resonating element.
An adjustable component such as a tunable inductor may be coupled between the antenna resonating element and antenna ground for tuning the antenna. The shorter portion of the antenna resonating element may be formed from a portion of the peripheral conductive electronic device housing structures and may serve as a first branch of an inverted-F antenna resonating element arm. The inverted-F antenna resonating element arm may also have a second branch. The first and second branches may be characterized by respective first and second antenna resonance peaks within the first communications band.
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.
Electronic devices such as electronic device 10 of
The antennas can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. The conductive electronic device structures may include conductive housing structures. The housing structures may include a peripheral conductive member that runs around the periphery of an electronic device. The peripheral conductive member may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, and/or may form other housing structures. Gaps in the peripheral conductive member may be associated with the antennas.
Electronic device 10 may be a portable electronic device or other suitable electronic device. For example, electronic device 10 may be a laptop computer, a tablet computer, a somewhat smaller device such as a wrist-watch device, pendant device, headphone device, earpiece device, or other wearable or miniature device, a cellular telephone, or a media player. Device 10 may also be a television, a set-top box, a desktop computer, a computer monitor into which a computer has been integrated, or other suitable electronic equipment.
Device 10 may include a housing such as housing 12. Housing 12, which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing 12 may be formed from dielectric or other low-conductivity material. In other situations, housing 12 or at least some of the structures that make up housing 12 may be formed from metal elements.
Device 10 may, if desired, have a display such as display 14. Display 14 may, for example, be a touch screen that incorporates capacitive touch electrodes. Display 14 may include image pixels formed from light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components, or other suitable image pixel structures. A display cover layer formed from clear glass, transparent plastic, or other transparent dielectric may cover the surface of display 14. Buttons such as button 19 may pass through openings in the display cover layer. The cover layer may also have other openings such as an opening for speaker port 26.
Housing 12 may include a peripheral member such as member 16. Member 16 may run around the periphery of device 10 and display 14. In configurations in which device 10 and display 14 have a rectangular shape, member 16 may have a rectangular ring shape (as an example). Member 16 or part of member 16 may serve as a bezel for display 14 (e.g., a cosmetic trim that surrounds all four sides of display 14 and/or helps hold display 14 to device 10). Member 16 may also, if desired, form sidewall structures for device 10 (e.g., by forming a metal band with vertical sidewalls surrounding the periphery of device 10, etc.).
Member 16 may be formed of a conductive material and may therefore sometimes be referred to as a peripheral conductive member, peripheral conductive housing member, or conductive housing structures. Member 16 may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures (e.g., segments) may be used in forming member 16.
It is not necessary for member 16 to have a uniform cross-section. For example, the top portion of member 16 may, if desired, have an inwardly protruding lip that helps hold display 14 in place. If desired, the bottom portion of member 16 may also have an enlarged lip (e.g., in the plane of the rear surface of device 10). In the example of
Display 14 may include conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. Housing 12 may include internal structures such as metal frame members, a planar housing member (sometimes referred to as a midplate) that spans the walls of housing 12 (i.e., a substantially rectangular member that is welded or otherwise connected between opposing sides of member 16), printed circuit boards, and other internal conductive structures. These conductive structures may be located in the center of housing 12 under display 14 (as an example).
In regions 22 and 20, openings may be formed within the conductive structures of device 10 (e.g., between peripheral conductive member 16 and opposing conductive structures such as conductive housing structures, a conductive ground plane associated with a printed circuit board, and conductive electrical components in device 10). These openings may be filled with air, plastic, and other dielectrics. Conductive housing structures and other conductive structures in device 10 may serve as a ground plane for the antennas in device 10. The openings in regions 20 and 22 may serve as slots in open or closed slot antennas, may serve as a central dielectric region that is surrounded by a conductive path of materials in a loop antenna, may serve as a space that separates an antenna resonating element such as a strip antenna resonating element or an inverted-F antenna resonating element from the ground plane, or may otherwise serve as part of antenna structures formed in regions 20 and 22.
In general, device 10 may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in device 10 may be located at opposing first and second ends of an elongated device housing, along one or more edges of a device housing, in the center of a device housing, in other suitable locations, or in one or more of such locations. The arrangement of
Portions of member 16 may be provided with gap structures. For example, member 16 may be provided with one or more gaps (splits) such as gaps 18, as shown in
In a typical scenario, device 10 may have upper and lower antennas (as an example). An upper antenna may, for example, be formed at the upper end of device 10 in region 22. A lower antenna may, for example, be formed at the lower end of device 10 in region 20. The antennas may be used separately to cover identical communications bands, overlapping communications bands, or separate communications bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO) antenna scheme.
Antennas in device 10 may be used to support any communications bands of interest. For example, device 10 may include antenna structures for supporting local area network communications, voice and data cellular telephone communications, global positioning system (GPS) communications or other satellite navigation system communications, Bluetooth® communications, etc.
A schematic diagram of an illustrative configuration that may be used for electronic device 10 is shown in
Storage and processing circuitry 28 may be used to run software on device 10, such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry 28 may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry 28 include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, etc.
Circuitry 28 may be configured to implement control algorithms that control the use of antennas in device 10. For example, circuitry 28 may perform signal quality monitoring operations, sensor monitoring operations, and other data gathering operations and may, in response to the gathered data and information on which communications bands are to be used in device 10, control which antenna structures within device 10 are being used to receive and process data and/or may adjust one or more switches, tunable elements, or other adjustable circuits in device 10 to adjust antenna performance. As an example, circuitry 28 may control which of two or more antennas is being used to receive incoming radio-frequency signals, may control which of two or more antennas is being used to transmit radio-frequency signals, may control the process of routing incoming data streams over two or more antennas in device 10 in parallel, may tune an antenna to cover a desired communications band, etc. In performing these control operations, circuitry 28 may open and close switches, may turn on and off receivers and transmitters, may adjust impedance matching circuits, may configure switches in front-end-module (FEM) radio-frequency circuits that are interposed between radio-frequency transceiver circuitry and antenna structures (e.g., filtering and switching circuits used for impedance matching and signal routing), may adjust switches, tunable circuits, and other adjustable circuit elements that are formed as part of an antenna or that are coupled to an antenna or a signal path associated with an antenna, and may otherwise control and adjust the components of device 10.
Input-output circuitry 30 may be used to allow data to be supplied to device 10 and to allow data to be provided from device 10 to external devices. Input-output circuitry 30 may include input-output devices 32. Input-output devices 32 may include touch screens, buttons, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, data ports, etc. A user can control the operation of device 10 by supplying commands through input-output devices 32 and may receive status information and other output from device 10 using the output resources of input-output devices 32.
Wireless communications circuitry 34 may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications).
Wireless communications circuitry 34 may include satellite navigation system receiver circuitry such as Global Positioning System (GPS) receiver circuitry 35 (e.g., for receiving satellite positioning signals at 1575 MHz) or satellite navigation system receiver circuitry associated with other satellite navigation systems. Transceiver circuitry 36 may handle wireless local area network communications. For example, transceiver circuitry 36 may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry 34 may use cellular telephone transceiver circuitry 38 for handling wireless communications in cellular telephone bands such as bands in frequency ranges of about 700 MHz to about 2700 MHz or bands at higher or lower frequencies. Wireless communications circuitry 34 can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry 34 may include wireless circuitry for receiving radio and television signals, paging circuits, etc. In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles.
Wireless communications circuitry 34 may include one or more antennas 40. Antennas 40 may be formed using any suitable antenna types. For example, antennas 40 may include antennas with resonating elements that are formed from loop antenna structure, patch antenna structures, inverted-F antenna structures, closed and open slot antenna structures, planar inverted-F antenna structures, helical antenna structures, strip antennas, monopoles, dipoles, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link.
If desired, one or more of antennas 40 may be provided with tunable circuitry. The tunable circuitry may include switching circuitry based on one or more switches. The switching circuitry may, for example, include a switch that can be placed in an open or closed position. When control circuitry 28 of device 10 places the switch in its open position, an antenna may exhibit a first frequency response. When control circuitry 28 of device 10 places the switch in its closed position, the antenna may exhibit a second frequency response. Tunable circuitry for one or more of antennas 40 may also be based on switching circuitry that can switch selected circuit components into use. For example, an adjustable inductor may operate in a first mode in which a first inductor is switched into use and a second mode in which a second inductor is switched into use. An adjustable inductor may optionally also be switched into a mode in which a short circuit is switched into use or in which an open circuit is formed. Using adjustable inductors such as these or other adjustable circuit components, the performance of antenna 40 may be adjusted in real time to cover operating frequencies of interest.
Antenna 40 may exhibit multiple resonances. For example, antenna 40 may be configured to exhibit resonances in a low band, a middle band, and a high band (as examples). Low band communications frequencies may include communications frequencies from 700 MHz to 960 MHz, middle band communications frequencies may include communications frequencies from 1710 to 2170 MHz, and high band communications frequencies may include communications frequencies from 2300 to 2700 MHz (as examples). Other communications frequencies can be covered using antenna 40, if desired. Configurations in which antenna 40 covers low, middle, and high communications bands are merely illustrative.
Adjustment of the state of adjustable inductors or other adjustable circuit components may be used to tune antenna 40. For example, adjustments to the state of one or more adjustable inductor circuits may be used to tune the low band response of antenna 40 without appreciably affecting the middle and high band responses. The ability to adjust the response of the antenna may allow the antenna to cover communications frequencies of interest.
A top interior view of device 10 in a configuration in which device 10 has a peripheral conductive housing member such as housing member 16 of
One or more segments of peripheral conductive member 16 may serve as antenna resonating elements for an antenna in device 10. For example, the uppermost segment of peripheral conductive member 16 in region 22 may serve as an antenna resonating element for an upper antenna in device 10 and the lowermost segment of peripheral conductive member 16 in region 20 (i.e., segment 16′, which extends between gap 18A and gap 18B) may serve as an antenna resonating element for a lower antenna in device 10. The conductive materials of peripheral conductive member 16, the conductive materials of ground plane 52, and dielectric-filled openings 82 (and gaps 18) may be used in forming one or more antennas in device 10 such as an upper antenna in region 22 and a lower antenna in region 20. Configurations in which an antenna in lower region 20 is implemented using a tunable frequency response configuration are sometimes described herein as an example.
Illustrative antenna structures of the type that may be used in device 10 (e.g., in region 20 and/or region 22) are shown in
As shown in
Transmission line structures 92 may be coupled to antenna feeds formed using antenna feed terminals 94-1 and 96-1 (which form a first antenna feed F1) and antenna feed terminals 94-2 and 96-2 (which form a second antenna feed F2). Terminal 94-1 may be a positive antenna feed terminal and terminal 96-1 may be a ground antenna feed terminal for first antenna feed F1. Terminal 94-2 may be a positive antenna feed terminal and terminal 96-2 may be a ground antenna feed terminal for second antenna feed F2.
The antenna feeds in antenna structures 40 may be used in handling the same types of signals or different types of signals. For example, the first feed may be used for transmitting and/or receiving antenna signals in a first communications band or first set of communications bands and the second feed may be used for transmitting and/or receiving antenna signals in a second communications band or second set of communications bands or the first and second feeds may collectively be used in transmitting signals in multiple communications bands (e.g., in a configuration in which transmission lines 92-1 and 92-2 are branches of a common transmission line that are coupled together using a splitter).
If desired, tunable components such as adjustable capacitors, adjustable inductors, filter circuitry such as band-pass filter circuitry, band-stop filter circuitry, high pass filter circuitry, and low pass filter circuitry, switches, impedance matching circuitry, duplexers, diplexers, splitters, and other circuitry may be interposed within transmission line paths 92 (i.e., between wireless circuitry 90 and the respective feeds of antenna structures 40). The different feeds in antenna structures 40 may each exhibit a different impedance and antenna resonance behavior as a function of operating frequency. Wireless circuitry 90 may therefore use different feeds or combinations of feeds for different signal frequencies, if desired. Duplexers or other filter circuitry may route signals to and from the feeds of antenna 40 as a function of frequency.
Antenna resonating element 50 may include a short circuit branch such as branch 98 that couples resonating element arm structures such as arms 100 and 102 to antenna ground 52. Arms such as arms 100 and 102 may be formed from segment 16′ of peripheral conductive housing member 16 or other conductive structures in device 10. Dielectric opening (gap) 82 separates arms 100 and 102 from antenna ground 52. Antenna ground 52 may be formed from housing structures such as a metal midplate member, printed circuit traces, metal portions of electronic components, or other conductive ground structures. Opening 82 may be formed by air, plastic, and other dielectric materials. Short circuit branch 98, which may sometimes be referred to as a return path or short circuit path, may be implemented using a strip of metal, a metal trace on a dielectric support structure such as a printed circuit or plastic carrier, or other conductive path that is coupled across dielectric-filled opening 82 and therefore bridges opening 82 between resonating element arm structures (e.g., arms 102 and/or 100) and antenna ground 52.
Antenna feed F1, which is formed using terminals 94-1 and 96-1, may be coupled in a path that bridges opening 82. Antenna feed F2, which is formed using terminals 94-2 and 96-2, may be coupled in a path that bridges opening 82 in parallel with feed F1 and in parallel with short circuit path 98.
Resonating element arms 100 and 102 may form respective arms in a dual arm inverted-F antenna resonating element. Arms 100 and 102 may have one or more bends. The illustrative arrangement of
Arm 100 may be a longer low-band arm that handles lower frequencies, whereas arm 102 may be a shorter high-band arm that handles higher frequencies. Arm 100 may allow antenna 40 to exhibit an antenna resonance at low band (LB) frequencies such as frequencies from 700 MHz to 960 MHz or other suitable frequencies. Arm 102 may allow antenna 40 to exhibit one or more antenna resonances at higher frequencies such as resonances at one or more frequencies in the range of 1710 to 2170 MHz (sometimes referred to as mid-band frequencies). Antenna 40 may also contain antenna resonating element structures (e.g., inverted-F antenna structures) that allow antenna 40 to resonate at higher frequencies such as frequencies between 2300 MHz to 2700 MHz (sometimes referred to as high band frequencies) or other suitable frequencies. The frequencies handled by antenna 40 may be cellular telephone frequencies and/or wireless local area network frequencies. Other frequencies (e.g., satellite navigation system frequencies, etc.) may also be handled if desired.
To provide antenna 40 with tuning capabilities, antenna 40 may include adjustable circuitry. The adjustable circuitry may be coupled between different locations on antenna resonating element 50. As shown in
The adjustable circuitry of antenna 40 such as adjustable inductor 110 or other adjustable circuitry may be tuned using control signals from control circuitry 28 (
Ground 52 may have an extended portion 52E (sometimes referred to as planar conductive structures) that may be configured to form return path 98 between inverted-F antenna resonating element 50 and ground plane 52. Extended portion 52E may also form additional inverted-F antenna resonating element 50′ for supporting high band (HB) communications when feed by antenna feed F2. A gap such as slot 204 may form an opening between portion 202 of extended portion 52E and portion 206 of ground 52. Portion 202 of extended portion 52E serves as the main arm of additional inverted-F antenna resonating element portion 50′ of antenna resonating element 50 and antenna 40. Portion 200 of extended portion 52E serves as a return path (short circuit path) in additional inverted-F antenna resonating element portion 50′ and is used to couple main arm portion 202 to ground 206.
Openings 18 between arms 100 and 102 may give rise to respective capacitances such as capacitances C1 and C2. Inductors may be incorporated into antenna 40 to compensate for one or both of capacitances C1 and C2. As shown in
In antenna 40 of
When both feeds are active in antenna 40 (e.g., when a shared transmission line is used that a splitter divides into a first transmission line coupled to feed F1 and a second transmission line coupled to feed F2 or when other paths are used to couple wireless circuitry 90 to antenna 40), antenna 40 may exhibit a response of the type shown in
If desired, additional conductive structures may be added to antenna 40 to modify the frequency performance of antenna 40. As shown in
The lengths of each branch may be about a quarter of a wavelength at a low band resonant frequency of interest. The longer of the two branches of the low band resonating element arm may resonant at a lower frequency than the shorter of the two branches of the low band portion of antenna resonating element 50. The presence of two branches of the low-frequency portion of inverted-F antenna resonating element arm may give rise to two corresponding resonances in low band LB. The resonances may be overlapping (to broaden low band performance) or may be distinct (i.e., a region of unsatisfactory antenna performance may separate two acceptable low band resonances).
Low band LB may extend from 700 to 960 MHz or may cover another suitable range of frequencies. Mid-band MB may lie within a frequency range of 1710 MHz to 2170 MHz or other suitable frequency range. As indicated by line 210, adjustable inductor 110 of antenna 40 of
When both feeds are active in antenna 40 (e.g., when a shared transmission line is used that a splitter divides into a first transmission line coupled to feed F1 and a second transmission line coupled to feed F2 or when wireless circuitry 90 is otherwise coupled to feeds F1 and F2), antenna 40 may exhibit a response of the type 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.
