Bezel Gap Antennas
Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. A parallel-fed loop antenna may be formed from portions of an electronic device bezel and a ground plane. The antenna may operate in multiple communications bands. An impedance matching circuit for the antenna may be formed from a parallel-connected inductive element and a series-connected capacitive element. The bezel may surround a peripheral portion of a display that is mounted to the front of an electronic device. The bezel may contain a gap. Antenna feed terminals for the antenna may be located on opposing sides of the gap. The inductive element may bridge the gap and the antenna feed terminals. The capacitive element may be connected in series between one of the antenna feed terminals and a conductor in a transmission line located between the transceiver circuitry and the antenna.
This application is a continuation of patent application Ser. No. 12/630,756, filed Dec. 3, 2009, which is hereby incorporated by referenced herein in its entirety. This application claims the benefit of and claims priority to patent application Ser. No. 12/630,756, filed Dec. 3, 2009.
BACKGROUNDThis relates generally to wireless communications circuitry, and more particularly, to electronic devices that have wireless communications circuitry.
Electronic devices such as 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.
Devices such as these 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 at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz (e.g., the main Global System for Mobile Communications or GSM cellular telephone bands). Long-range wireless communications circuitry may also handle the 2100 MHz band. Electronic devices may use short-range wireless communications links to handle communications with nearby equipment. For example, electronic devices may communicate using the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5 GHz and the Bluetooth° band at 2.4 GHz.
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 components can affect radio-frequency performance, care must be taken when incorporating antennas into an electronic device that includes conductive structures.
It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless electronic devices.
SUMMARYElectronic devices may be provided that include antenna structures. An antenna may be configured to operate in first and second communications bands. An electronic device may contain radio-frequency transceiver circuitry that is coupled to the antenna using a transmission line. The transmission line may have a positive conductor and a ground conductor. The antenna may have a positive antenna feed terminal and a ground antenna feed terminal to which the positive and ground conductors of the transmission line are respectively coupled.
The electronic device may have a rectangular periphery. A rectangular display may be mounted on a front face of the electronic device. The electronic device may have a rear face that is formed form a plastic housing member. Conductive sidewall structures may run around the periphery of the electronic device housing and display. The conductive sidewall structures may serve as a bezel for the display.
The bezel may include at least one gap. The gap may be filled with a solid dielectric such as plastic. The antenna may be formed from the portion of the bezel that includes the gap and a portion of a ground plane. To avoid excessive sensitivity to touch events, the antenna may be fed using a feed arrangement that reduces electric field concentration in the vicinity of the gap. An impedance matching network may be formed that provides satisfactory operation in both the first and second bands.
The impedance matching network may include an inductive element that is formed in parallel with the antenna feed terminals and a capacitive element that is formed in series with one of the antenna feed terminals.
The inductive element may be formed from a transmission line inductive structure that bridges the antenna feed terminals. The capacitive element may be formed from a capacitor that is interposed in the positive feed path for the antenna. The capacitor may, for example, be connected between the positive ground conductor of the transmission line and the positive antenna feed terminal.
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 may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support wireless communications in multiple wireless communications bands. The wireless communications circuitry may include one or more antennas.
The antennas can include loop antennas. Conductive structures for a loop antenna 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 conductive bezel. Gap structures may be formed in the conductive bezel. The antenna may be parallel-fed using a configuration that helps to minimize sensitivity of the antenna to contact with a user's hand or other external object.
Any suitable electronic devices may be provided with wireless circuitry that includes loop antenna structures. As an example, loop antenna structures may be used in electronic devices such as desktop computers, game consoles, routers, laptop computers, etc. With one suitable configuration, loop antenna structures are provided in relatively compact electronic devices in which interior space is relatively valuable such as portable electronic devices.
An illustrative portable electronic device in accordance with an embodiment of the present invention is shown in
Space is at a premium in portable electronic devices. Conductive structures are also typically present, which can make efficient antenna operation challenging. For example, conductive housing structures may be present around some or all of the periphery of a portable electronic device housing.
In portable electronic device housing arrangements such as these, it may be particularly advantageous to use loop-type antenna designs that cover communications bands of interest. The use of portable devices such as handheld devices is therefore sometimes described herein as an example, although any suitable electronic device may be provided with loop antenna structures, if desired.
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. Handheld devices and other portable devices may, if desired, include the functionality of multiple conventional devices. Examples of multi-functional devices include cellular telephones that include media player functionality, gaming devices that include wireless communications capabilities, cellular telephones that include game and email functions, and handheld devices that receive email, support mobile telephone calls, and support web browsing. These are merely illustrative examples.
Device 10 of
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 form light-emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electronic ink elements, liquid crystal display (LCD) components, or other suitable image pixel structures. A cover glass member may cover the surface of display 14. Buttons such as button 19 may pass through openings in the cover glass.
Housing 12 may include sidewall structures such as sidewall structures 16. Structures 16 may be implemented using conductive materials. For example, structures 16 may be implemented using a conductive ring member that substantially surrounds the rectangular periphery of display 14. Structures 16 may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming structures 16. Structures 16 may serve as a bezel that holds display 14 to the front (top) face of device 10. Structures 16 are therefore sometimes referred to herein as bezel structures 16 or bezel 16. Bezel 16 runs around the rectangular periphery of device 10 and display 14.
Bezel 16 may have a thickness (dimension TT) of about 0.1 mm to 3 mm (as an example). The sidewall portions of bezel 16 may be substantially vertical (parallel to vertical axis V). Parallel to axis V, bezel 16 may have a dimension TZ of about 1 mm to 2 cm (as an example). The aspect ratio R of bezel 16 (i.e., the of TZ to TT) is typically more than 1 (i.e., R may be greater than or equal to 1, greater than or equal to 2, greater than or equal to 4, greater than or equal to 10, etc.).
It is not necessary for bezel 16 to have a uniform cross-section. For example, the top portion of bezel 16 may, if desired, have an inwardly protruding lip that helps hold display 14 in place. If desired, the bottom portion of bezel 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 includes conductive structures such as an array of capacitive electrodes, conductive lines for addressing pixel elements, driver circuits, etc. These conductive structures tend to block radio-frequency signals.
It may therefore be desirable to form some or all of the rear planar surface of device from a dielectric material such as plastic.
Portions of bezel 16 may be provided with gap structures. For example, bezel 16 may be provided with one or more gaps such as gap 18, as shown in
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 lower antenna may, for example, be formed partly from the portions of bezel 16 in the vicinity of gap 18.
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, Bluetooth° communications, etc. As an example, the lower antenna in region 20 of device 10 may be used in handling voice and data communications in one or more cellular telephone bands.
A schematic diagram of an illustrative electronic device is shown in
As 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.
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 devices 32 such as touch screens and other user input interface are examples of input-output circuitry 32. Input-output devices 32 may also include user input-output devices such as buttons, 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 such user input devices. Display and audio devices such as display 14 (
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 radio-frequency transceiver circuits for handling multiple radio-frequency communications bands. For example, circuitry 34 may include transceiver circuitry 36 and 38. 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 the GSM bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, and the 2100 MHz data band (as examples). 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 global positioning system (GPS) receiver equipment, 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 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, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link.
With one suitable arrangement, which is sometimes described herein as an example, the lower antenna in device (i.e., an antenna 40 located in region 20 of device 10 of
A cross-sectional side view of device 10 of
Device 10 may contain printed circuit boards such as printed circuit board 46. Printed circuit board 46 and the other printed circuit boards in device 10 may be formed from rigid printed circuit board material (e.g., fiberglass-filled epoxy) or flexible sheets of material such as polymers. Flexible printed circuit boards (“flex circuits”) may, for example, be formed from flexible sheets of polyimide.
Printed circuit board 46 may contain interconnects such as interconnects 48. Interconnects 48 may be formed from conductive traces (e.g., traces of gold-plated copper or other metals). Connectors such as connector 50 may be connected to interconnects 48 using solder or conductive adhesive (as examples). Integrated circuits, discrete components such as resistors, capacitors, and inductors, and other electronic components may be mounted to printed circuit board 46.
Antenna 40 may have antenna feed terminals. For example, antenna 40 may have a positive antenna feed terminal such as positive antenna feed terminal 58 and a ground antenna feed terminal such as ground antenna feed terminal 54. In the illustrative arrangement of
As the cross-sectional view of
Consider, as an example, the antenna arrangement of
Ground plane extensions 70 (i.e., portions of bezel 16) and the portions of region 68 that lie along edge 76 of ground region 68 form a conductive loop around opening 72. Opening 72 may be formed from air, plastics and other solid dielectrics. If desired, the outline of opening 72 may be curved, may have more than four straight segments, and/or may be defined by the outlines of conductive components. The rectangular shape of dielectric region 72 in
The conductive structures of
To ensure that antenna 40 is not overly sensitive to touch (i.e., to desensitize antenna 40 to touch events involving the hand of the user of device 10 and other external objects), antenna 40 may be fed using antenna feed terminals located in the vicinity of gap 18 (e.g., where shown by positive antenna feed terminal 58 and ground antenna feed terminal 54 in the
In the arrangement of
It may be challenging to effectively use a series-fed feed arrangement of the type shown in
A standing-wave-ratio (SWR) versus frequency plot that illustrates this effect is shown in
A more satisfactory level of performance (illustrated by low-band resonant peak 92) may be obtained using a parallel-fed arrangement with appropriate impedance matching features.
An illustrative parallel-fed loop antenna is shown schematically in
Element 98 may be formed from one or more electrical components. Components that may be used as all or part of element 98 include resistors, inductors, and capacitors. Desired resistances, inductances, and capacitances for element 98 may be formed using integrated circuits, using discrete components and/or using dielectric and conductive structures that are not part of a discrete component or an integrated circuit. For example, a resistance can be formed using thin lines of a resistive metal alloy, capacitance can be formed by spacing two conductive pads close to each other that are separated by a dielectric, and an inductance can be formed by creating a conductive path on a printed circuit board. These types of structures may be referred to as resistors, capacitors, and/or inductors or may be referred to as capacitive antenna feed structures, resistive antenna feed structures and/or inductive antenna feed structures.
An illustrative configuration for antenna 40 in which component 98 of the schematic diagram of
The presence of inductor 98 may at least partly help match the impedance of transmission line 52 to antenna 40. If desired, inductor 98 may be formed using a discrete component such as a surface mount technology (SMT) inductor. The inductance of inductor 98 may also be implemented using an arrangement of the type shown in
Capacitive tuning may also be used to improve impedance matching for antenna 40. For example, capacitor 100 of
The conductive loop for loop antenna 40 of
During operation of antenna 40, a variety of current paths 102 of different lengths may be formed through ground plane 68. This may help to broaden the frequency response of antenna 40 in bands of interest. The presence of tuning elements such as parallel inductance 98 and series capacitance 100 may help to form an efficient impedance matching circuit for antenna 40 that allows antenna 40 to operate efficiently at both high and low bands (e.g., so that antenna 40 exhibits high-band resonance peak 94 of
A simplified Smith chart showing the possible impact of tuning elements such as inductor 98 and capacitor 100 of
With parallel-fed antenna 40 of
At point X3, antenna 40 is well matched to the impedance of cable 50 in both the high band (frequencies centered about frequency f2 in
Moreover, the placement of point X3 helps ensure that detuning due to touch events is minimized. When a user touches housing 12 of device 10 in the vicinity of antenna 40 or when other external objects are brought into close proximity with antenna 40, these external objects affect the impedance of the antenna. In particular, these external objects may tend to introduce a capacitive impedance contribution to the antenna impedance. The impact of this type of contribution to the antenna impedance tends to move the impedance of the antenna from point X3 to point X4, as illustrated by line 106 of chart 104 in
Although the diagram of
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.
Claims
1. An electronic device, comprising:
- a housing having a periphery;
- a conductive structure that runs along the periphery and that has at least one gap on the periphery; and
- an antenna formed at least partly from the conductive structure.
2. The electronic device defined in claim 1 further comprising a display, wherein the conductive structure comprises a bezel for the display.
3. The electronic device defined in claim 2 further comprising first and second antenna feed terminals for the antenna, wherein the antenna comprises a parallel-fed loop antenna.
4. The electronic device defined in claim 3 further comprising:
- a substantially rectangular ground plane, wherein a portion of the loop antenna is formed from the substantially rectangular ground plane.
5. The electronic device defined in claim 4 wherein the second antenna feed terminal is connected to the substantially rectangular ground plane.
6. The electronic device defined in claim 4 wherein the second antenna feed terminal is connected to the substantially rectangular ground plane and wherein the first antenna feed terminal is electrically connected to the bezel.
7. The electronic device defined in claim 1 wherein the conductive structure forms a conductive loop path, the electronic device further comprising an inductor interposed in the conductive loop path.
8. The electronic device defined in claim 1 further comprising first and second antenna feed terminals for the antenna, wherein the first and second antenna feed terminals are located on opposing sides of the gap.
9. The electronic device defined in claim 1 further comprising a transmission line having first and second conductors respectively connected to first and second antenna feed terminals for the antenna and a capacitor between the first conductor of the transmission line and the first antenna feed terminal.
9. The electronic device defined in claim 1 further comprising first and second antenna feed terminals for the antenna and an inductor coupled between the first and second antenna feed terminals.
10. An electronic device, comprising:
- a housing having a periphery;
- a ground plane in the housing;
- a conductive structure that runs along the periphery and that has at least one gap on the periphery;
- an open antenna slot formed partly by the conductive structure and partly by the ground plane, wherein the open antenna slot has an opening formed by the gap.
11. The electronic device defined in claim 10 further comprising:
- a closed antenna slot formed partly by the conductive structure and partly by the ground plane.
12. The electronic device defined in claim 11 further comprising:
- an L-shaped conductive region that forms edges of both the open and closed antenna slots and that is disposed between the open and closed antenna slots.
13. The electronic device defined in claim 12 further comprising:
- radio-frequency transceiver circuitry;
- first and second antenna feed terminals; and
- a transmission line having positive and ground conductors, wherein the transmission line is coupled between the radio-frequency transceiver circuitry and the first and second antenna feed terminals.
14. The electronic device defined in claim 13 wherein the first antenna feed terminal is located on the ground plane and wherein the second antenna feed terminal is located on the L-shaped conductive region.
15. The electronic device defined in claim 14 further comprising a display, wherein the conductive structure comprises a bezel for the display.
16. Wireless circuitry, comprising:
- a ground plane;
- a conductive electronic device bezel having a gap;
- a solid dielectric that fills the gap; and
- first and second antenna feed terminals, wherein the ground plane, bezel, and first and second antenna feed terminals form a parallel-fed loop antenna.
17. The wireless circuitry defined in claim 16 wherein the parallel-fed loop antenna comprises an open slot, wherein the open slot has an opening formed by the gap in the conductive electronic device bezel.
18. The wireless circuitry defined in claim 17 wherein the first and second antenna feed terminals are located on opposing sides of the gap.
19. The wireless circuitry defined in claim 18 wherein the parallel-fed loop antenna further comprises a closed slot, wherein the open and closed slots are each partly defined by the conductive electronic device bezel and by the ground plane, the wireless circuitry further comprising L-shaped conductive structures separating the open and closed slots.
20. The wireless circuitry defined in claim 19 wherein the open slot has approximately rectangular shaped interior region and wherein the open slot has an approximately L-shaped interior region.
Type: Application
Filed: Sep 14, 2012
Publication Date: Jan 10, 2013
Inventors: Mattia Pascolini (Campbell, CA), Robert J. Hill (Salinas, CA), Juan Zavala (Watsonville, CA), Nanbo Jin (Sunnyvale, CA), Qingxiang Li (Mountain View, CA), Robert W. Schlub (Campbell, CA), Ruben Caballero (San Jose, CA)
Application Number: 13/620,188
International Classification: H01Q 1/24 (20060101);