PATENT DOCUMENT

Publication Number: US-7623078-B2
Application Number: US-63990506-A
Country: US
Kind Code: B2

Title: Antenna for portable electronic device wireless communications adapter

Abstract:
Antennas are provided for portable electronic devices. A portable electronic device may have a port that receives a wireless communications adapter. The adapter may be used to provide wireless functionality for the portable electronic device. The adapter may contain a chip antenna that serves as an antenna resonating element. A printed circuit board within the adapter may contain conductor that has been patterned to form a ground plane for the antenna. The portable electronic device may have a conductive structure such as a housing portion. The conductive structure of the portable electronic device serves as a parasitic antenna element that improves antenna efficiency. The portable electronic device may be a handheld electronic device with music player functionality that communicates with a compact portable wireless device in a piece of sports equipment.

Claims:
1. An antenna associated with a wireless communications adapter for a portable electronic device, wherein the antenna is formed partly using a conductive structure in the portable electronic device that serves as a parasitic antenna element, the antenna comprising:
 a discrete surface mount antenna structure in the wireless communication adapter that forms a resonating element for the antenna; 
 a printed circuit board ground plane in the wireless communications adapter that forms an antenna ground for the antenna, wherein the discrete surface mount antenna structure is mounted to the printed circuit board; and 
 a resistor that electrically connects the ground plane and the conductive structure in the portable electronic device that serves as the parasitic antenna element. 
 
   
   
     2. The antenna defined in  claim 1  wherein the discrete surface mount antenna comprises a helical chip antenna. 
   
   
     3. The antenna defined in  claim 1  wherein the conductive structure comprises a conductive handheld electronic device housing and a portion of at least one multipin connector. 
   
   
     4. The antenna defined in  claim 1  wherein the portable electronic device comprises a handheld electronic device having a housing, wherein the discrete surface mount antenna structure comprises a chip antenna, and wherein the conducting structure comprises at least a conductive portion of the housing of the handheld electronic device. 
   
   
     5. An antenna that is associated with a handheld electronic device and a separate wireless communications adapter that is mounted to the handheld electronic device, the antenna comprising:
 an antenna structure in the wireless communication adapter that forms a resonating element for the antenna; 
 a ground plane in the wireless communications adapter that forms an antenna ground for the antenna; and 
 a conductive handheld electronic device housing portion of the handheld electronic device that forms a parasitic antenna element for the antenna. 
 
   
   
     6. The antenna defined in  claim 5 , wherein the wireless communications adapter and handheld electronic devices each comprise a respective mating multipin connector, the antenna further comprising:
 metal shield portions formed from the multipin connectors that are electrically connected to the conductive handheld electronic device housing portion and that form part of the parasitic antenna element, wherein the metal shield portions are not shorted to the ground plane. 
 
   
   
     7. The antenna defined in  claim 5  further comprising a resistor that is electrically connected between the ground plane in the wireless communications adapter and the conductive handheld electronic device housing portion. 
   
   
     8. Electronic equipment comprising:
 a handheld electronic device comprising:
 processing circuitry that generates and consumes data; and 
 a conductive housing portion that forms a parasitic antenna element; 
 a handheld electronic device connector having a shield that is electrically connected to the conductive housing portion; and 
 
 a wireless communications adapter that is mounted to the handheld electronic device, comprising:
 a printed circuit board; 
 a wireless communications connector that is mounted to the printed circuit board and that has a shield that is electrically connected to the handheld electronic device connector; 
 an antenna ground plane formed on the printed circuit board; 
 a resonating antenna element mounted to the printed circuit board, wherein the resonating antenna element, the antenna ground plane, and the parasitic antenna element form an antenna for the wireless communications adapter; and 
 a radio-frequency transceiver mounted to the printed circuit board that transmits and receives the data as radio-frequency signals through the antenna. 
 
 
   
   
     9. The electronic equipment defined in  claim 8  wherein the handheld electronic device comprises a device with music player functionality and wherein the conductive housing portion comprises metal. 
   
   
     10. The electronic equipment defined in  claim 8  wherein the ground plane is formed from at least one metal layer within the printed circuit board and is spaced at least 2 mm from the resonating antenna element and wherein the resonating element comprises a chip antenna. 
   
   
     11. The electronic equipment defined in  claim 8  further comprising:
 a resistor that is mounted to the circuit board and that is electrically connected between the antenna ground plane and the shield of the wireless communications adapter connector. 
 
   
   
     12. The electronic equipment defined in  claim 8  wherein the handheld electronic device connector and the wireless communications adapter connector comprise mating pins. 
   
   
     13. The electronic equipment defined in  claim 8  wherein the handheld electronic device connector and the wireless communications adapter connector comprise mating pins, the handheld electronic device further comprising a printed circuit board comprising a digital ground, wherein at least one of the pins electrically connects the ground plane in the wireless communications adapter to the digital ground of the handheld electronic device. 
   
   
     14. The electronic equipment defined in  claim 8  wherein the handheld electronic device connector comprises a first plurality of pins, wherein the wireless communications adapter connector comprises a second plurality of pins, wherein the shield of the wireless communications adapter connector mates with the shield of the handheld electronic device connector and is electrically connected to the shield of the handheld electronic device connector, and wherein the first pins mate with the second pins, the handheld electronic device further comprising a printed circuit board comprising a digital ground, wherein at least one of the first pins and at least one of the second pins electrically connect the ground plane in the wireless communications adapter to the digital ground of the handheld electronic device. 
   
   
     15. The electronic equipment defined in  claim 8  wherein the shield of the handheld electronic device connector comprises a first metal shield, wherein the handheld electronic device connector comprises a first plurality of pins, wherein the shield of the wireless communications adapter connector comprises a second metal shield, wherein the wireless communications adapter connector comprises a second plurality of pins, wherein the first metal shield mates with the second metal shield and is electrically connected to the second metal shield, and wherein the first pins mate with the second pins, the handheld electronic device further comprising a printed circuit board comprising a digital ground, wherein at least one of the first pins and at least one of the second pins electrically connect the ground plane in the wireless communications adapter to the digital ground of the handheld electronic device, and wherein the printed circuit board in the wireless communications adapter and the printed circuit board in the handheld electronic device are coplanar. 
   
   
     16. The electronic equipment defined in  claim 8  wherein the shield of the handheld electronic device connector comprises a first metal shield, wherein the handheld electronic device connector comprises a first plurality of pins, wherein the shield of the wireless communications adapter connector comprises a second metal shield, wherein the wireless communications adapter connector comprises a second plurality of pins, wherein the first metal shield mates with the second metal shield and is electrically connected to the second metal shield, and wherein the first pins mate with the second pins, the handheld electronic device further comprising a printed circuit board comprising a digital ground, wherein at least one of the first pins and at least one of the second pins electrically connect the ground plane in the wireless communications adapter to the digital ground of the handheld electronic device, and wherein the wireless communications adapter wirelessly communicates with a compact portable wireless device in a shoe over a communications link operating in a frequency range of 2.4-2.7 GHz, the antenna being configured to transmit and receive radio-frequency signals in the frequency range of 2.4-2.7 GHz. 
   
   
     17. The electronic equipment defined in  claim 8  wherein the handheld electronic device comprises a display and a user input interface. 
   
   
     18. The electronic equipment defined in  claim 8  wherein the handheld electronic device has lateral dimensions that are less than about 11 cm and wherein the conductive housing portion comprises metal. 
   
   
     19. The electronic equipment defined in  claim 8  wherein the handheld electronic device has lateral dimensions in the range of 2 cm to 12 cm and wherein the conductive housing portion comprises metal. 
   
   
     20. The electronic equipment defined in  claim 8  wherein the handheld electronic device connector and the wireless communications adapter connector are each 30 pin connectors having 30 pins for conveying data and ground signals.

Description:
BACKGROUND 
   This invention relates generally to antennas, and more particularly, to antennas in wireless communications adapters for portable electronic devices. 
   As integrated circuit technology advances, it is becoming feasible to construct portable wireless devices with small form factors. Examples of portable wireless devices include mobile telephones, wireless headsets, digital cameras with wireless capabilities, remote controls, wristwatch-type devices, music players with wireless functions, and handheld computers. Devices such as these are often small enough to be held in the hand and may sometimes be referred to as handheld electronic devices. Larger portable wireless devices include laptop computers. 
   Portable electronic devices sometimes use antennas to transmit and receive radio-frequency signals. For example, handheld computers often contain short-range antennas for handling wireless connections with wireless access points. Other portable electronic devices have no built-in wireless communications capabilities or have only limited wireless functions. 
   In situations in which a portable electronic device does not have sufficient built-in wireless capabilities, a wireless communications adapter may be used to supply the portable electronic device with wireless communications capabilities. 
   It is generally desirable for an antenna in a wireless communications adapter for a portable electronic wireless device to exhibit a high efficiency. Antennas with high efficiencies are less likely to consume excessive power than inefficient antennas and are therefore able to operate using smaller power supplies. Large bandwidths are also sometimes desired. At the same time, it is generally desirable to make wireless communications adapters as small as reasonably possible. To a large extent, these requirements compete with each other. Conventional antenna arrangements that are small tend not to be efficient and have small bandwidths, whereas efficient wideband antennas tend to take up a fairly large volume. 
   It would therefore be desirable to be able to provide improved antennas for wireless communications adapters for portable electronic devices. 
   SUMMARY 
   In accordance with the present invention, a portable electronic device and a wireless communications adapter for the portable electronic device are provided. The portable electronic device may be a handheld device with music player functionality or any other suitable device. The portable electronic device may have a multipin connector that mates with a matching multipin connector on the wireless communications adapter. 
   The wireless communications adapter has an antenna that is used to handle wireless radio-frequency signals for the portable electronic device. Processing circuitry in the portable electronic device is used to generate data to be transmitted and is used to consume wirelessly received data. The processing circuitry communicates with transceiver circuitry in the wireless communications adapter using signal and data pins in the matching multipin connectors. 
   The wireless communications adapter may have a printed circuit board. One or more conductive layers on the printed circuit board may be used to form a ground plane for the antenna. A discrete surface mounted antenna structure such as a chip antenna based on a ceramic-encapsulated helical antenna structure may be mounted to the printed circuit board. The chip antenna may serve as the antenna&#39;s resonating element. 
   The portable electronic device may have a housing that is formed at least partly from a conductive material such as metal. The conductive housing portion of the portable electronic device is coupled to the ground plane and resonating element portions of the antenna through near-field radio-frequency coupling and forms a parasitic antenna element for the antenna. A resistor may be provided in the wireless communications adapter to electrically connect the ground plane with the conductive housing portion without shorting the conductive housing portion to the ground plane. 
   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 schematic diagram of an illustrative system including a portable electronic device and wireless communications adapter with an antenna in accordance with an embodiment of the present invention. 
       FIG. 2  is a perspective view of an illustrative handheld electronic device with a wireless communications adapter in communication with a compact portable wireless device that has been installed in a running shoe in accordance with an embodiment of the present invention. 
       FIG. 3  is a schematic diagram of an illustrative handheld electronic device with a wireless communications adapter in communication with a wireless device, accessories, and computing equipment in accordance with an embodiment of the present invention. 
       FIG. 4  is a perspective view of an illustrative portable electronic device with a wireless communications adapter in accordance with an embodiment of the present invention. 
       FIG. 5  is a simplified cross-sectional view of an illustrative wireless communications adapter and a portable electronic device in accordance with an embodiment of the present invention. 
       FIG. 6  is a perspective view of an interior portion of a wireless communications adapter in accordance with an embodiment of the present invention. 
       FIG. 7  is a plan view of a printed circuit board and associated components for a wireless communications adapter in accordance with an embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   An illustrative system that contains a portable electronic device with a wireless communications adapter in accordance with an embodiment the present invention is shown in  FIG. 1 . As shown in  FIG. 1 , portable electronic device  18  may have wireless communications adapter  36  for communicating with other equipment over wireless communications path  16 . In the example of  FIG. 1 , wireless path  16  forms a communications link to compact portable wireless device  12  in sports equipment  14 . This is merely illustrative. Portable electronic device  18  and wireless communications adapter  36  may communicate wirelessly with any suitable electronic equipment. The arrangement in  FIG. 1  is presented as an example. 
   Wireless communications adapter  36  and portable electronic device  18  may contain antenna structures that work together to form an antenna. The antenna supports wireless communications over path  16  and may exhibit a high efficiency and wide bandwidth. Adapter  36  may be used to provide wireless communications capabilities for any suitable electronic device, including personal computers, portable computers, handheld devices, etc. Suitable handheld devices that may use adapter  36  may include cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, global positioning system (GPS) devices, handheld gaming devices, and 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, and supports web browsing. 
   Although antennas in accordance with the present invention may be used in any suitable wireless device, it can be particularly advantageous to use the antennas in devices with relatively small form-factors, because the potentially small size occupied by adapter  36  can be advantageous when space is at a premium. Antennas, wireless communications adapters, and electronic devices in accordance with the invention are therefore often described herein in the context of portable electronic devices, such as portable electronic device  18  of  FIG. 1 . 
   Portable electronic devices, such as device  18  of  FIG. 1 , may be portable computers, wrist devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. As shown in  FIG. 1 , device  18  may be a handheld electronic device. With one particularly suitable arrangement, device  18  may be a handheld electronic device that includes media player functionality and that includes circuitry for using adapter  36  to communicate wirelessly with a wireless pedometer module that is installed in the sole of a running shoe (i.e., compact portable wireless pedometer device  12  in shoe  14 ). Once installed in the running shoe, device  12  can wirelessly communicate with device  18  over link  16 . Device  12  may, as an example, gather information on how many steps a runner is taking and may transmit this information to device  18  for processing. 
   As shown in  FIG. 1 , compact portable wireless device  12  may communicate with adapter  36  and portable electronic device  18  over wireless communications path  16 . Wireless communications path  16  may be a Bluetooth communications path, an IEEE 802.11 wireless communications path (i.e., a WiFi path), a communications path using a custom wireless protocol, or any other suitable wireless communications path. The frequency range covered by path  16  may be about 2.4-2.7 GHz. This is merely illustrative. Path  16  may use any suitable communications band if desired. 
   The operation of portable electronic device  18  is sometimes described in the context of handheld electronic devices as an example. A handheld electronic device may be, for example, a cellular telephone, a media player with integrated wireless communications capabilities or with wireless communications capabilities that are provided using a plug-in wireless adapter, a handheld computer (personal digital assistant), a remote controller, a global positioning system (GPS) device, a handheld gaming device, or a hybrid device that combines the functionality of two or more such devices. For example, a handheld device may be a hybrid device formed by combining music player and cellular telephone functionality. 
   Electronic device  18  may communicate with additional electronic equipment. As shown in  FIG. 1 , electronic device  18  may communicate with user computing equipment  54  over communications link  22 . User computing equipment  54  may be any suitable computing equipment including a personal computer, a laptop computer, a handheld computer, a mainframe computer, a workstation, equipment that contains embedded processors, etc. With one suitable arrangement, user computing equipment  54  is a personal computer that has a port that receives portable electronic device  18 . The port may be, as an example, a Firewire or universal serial bus port or a dedicated port built into a docking station. When portable electronic device  18  is connected to the port, portable electronic device  18  may gather data from compact portable wireless device  12  and may transfer this data to user computing equipment  54  over communications path  22 . 
   User computing equipment  54  may be connected to server  26  and other user computing equipment  28  over a communications network  24 . Communications network  24  may include local area networks, wide area networks such as the internet, or any other suitable communications networks. Server  26  may be implemented using one or more computers at one or more geographic locations. Server  26  may be used to implement a collaborative service that supports athletes or other users who each have a respective compact portable wireless device and a respective handheld electronic device and wireless communications adapter. As an example, server  26  may be used to implement a service in which runners can track their training progress and can compete in virtual competitions with other runners. Compact portable wireless device  12  may be used to gather training data and data for virtual races. During a runner&#39;s training run or race, portable electronic device  18  and adapter  36  may wirelessly gather data that is captured using a sensor in compact portable wireless device  12 . After the training run or race is complete, the captured data may be downloaded to user computing equipment  54  over communications path  22 . 
   Once the data has been downloaded to user computing equipment  54 , a user can use an application running on user computing equipment  54  to process the data (e.g., to track the user&#39;s training progress, to compute running speeds throughout a particular run, to compare the data against historical data, etc.). The user can also upload the data from user computing equipment  54  to server  26 . Server  26  can use the data that has been uploaded from multiple users. For example, server  26  can compare the performance of two or more runners to determine which runner has won a virtual race. So long as these runners are able to upload the data from their compact portable wireless devices to server  26 , server  26  can compare their performance. It is not necessary for the runners to share the same physical location. 
     FIG. 2  is a perspective view of an illustrative handheld electronic device with a wireless communications adapter in communication with an illustrative compact portable wireless device. As shown in  FIG. 2 , wireless communications adapter  36  plugs into handheld electronic device  18 . Device  18  may be any suitable electronic device, such as a music player, a handheld computer, a cellular telephone, a hybrid device, etc. 
   Device  18  may have input-output devices such as a display screen  32 , user input-output controls  34 , and input-output port  30 . Display screen  32  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. As shown in the example of  FIG. 2 , display screens such as display screen  32  can be mounted on a front face of the handheld electronic device. If desired, displays such as display  32  can be mounted on the rear face of the handheld electronic device or on a side or other portion of the device of the device. Visual indicators such as light-emitting diodes (LEDs) may be used instead of or in conjunction with screen  32  to provide visual status information to a user. 
   A user of handheld device  18  may supply input commands using user input interface  34 . User input interface  34  may 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 touch screen (e.g., a touch screen implemented as part of screen  32 ), or any other suitable interface for controlling device  18 . Although shown schematically as being formed on the top face of the main unit of handheld electronic device  18  in the example of  FIG. 2 , user input interface  34  may generally be formed on any suitable portion of handheld electronic device  18 . For example, a button or other user interface control may be formed on the side of device  18  or on adapter  36 . If desired, device  18  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth remote control, etc.). 
   Handheld electronic device  18  may have ports such as port  30 . Port  30  may be, as an example, a 30-pin electrical connector that mates with corresponding 30-pin electrical connectors on other components (e.g., connectors on cables, docking stations, etc.). As shown in  FIG. 2 , adapter  36  has connector  37 , which mates with connector  30 . When adapter  36  is inserted into connector  30 , adapter  36  can be used to provide wireless transmit and receive functions for device  18 . Adapter  36  may include antenna structures and radio-frequency transceiver circuitry that allow adapter  36  to communicate with compact portable wireless device  12  over communications path  16 . Adapter  36  may also include communications circuitry that supports communications between adapter  36  and main unit  38 . 
   In the example of  FIG. 2 , compact wireless device  12  has been installed in running shoe  14 . Compact portable wireless device  12  may be manufactured as part of shoe  14  (or other suitable athletic equipment) or may be installed by a user. A user may, for example, install compact portable wireless device  12  in shoe  14  by lifting the insole of shoe  14  and placing compact portable wireless device  12  in a recess formed within the sole of shoe  14  under the insole. 
   A schematic diagram of handheld electronic device  18  and wireless communications adapter  36  in communication with compact portable wireless device  12  and other devices is shown in  FIG. 3 . Handheld device  18  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. 3 , handheld device  18  may include storage  40 . Storage  40  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash or other electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
   Processing circuitry  42  may be used to control the operation of device  18 . Processing circuitry  42  may be based on a processor such as a microprocessor and other suitable integrated circuits. During operation, processing circuitry  42  generates data that may be transmitted as radio-frequency signals through the antenna associated with wireless communications adapter  36  and consumes data that may have been received as radio-frequency signals through the antenna. 
   Input-output devices  44  may allow data to be supplied to device  18  and may allow data to be provided from device  18  to external devices. Input-output devices can include user input devices  46  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  18  by supplying commands through user input devices  46 . Display and audio devices  48  may include liquid-crystal display (LCD) screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  48  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  48  may contain audio-video interface equipment such as jacks for external headphones and monitors. 
   Handheld electronic device  18  and wireless communications adapter  36  may contain communications circuitry that allows handheld electronic device  18  and wireless communications adapter  36  to exchange data through signal pins in connectors  30  and  37  ( FIG. 2 ). 
   Wireless communications adapter  36  may contain wireless communications devices  50 . Wireless communications devices  50  may include communications circuitry such as RF transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, antennas, and other circuitry for generating and receiving RF wireless signals. 
   Device  18  can use wireless communications adapter  36  to communicate with compact portable wireless device  12  over wireless communications path  16 . Device  18  may also communicate with external devices such as accessories  52  and computing equipment  54 , as shown by paths  56 . Paths  56  may be wired paths. If desired, device  18  may include internal wireless circuitry or may use adapter  36  to communicate wirelessly over paths  56 . 
   Accessories  52  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  54  may be a server from which songs, videos, or other media are downloaded over a cellular telephone link or other wireless link. Computing equipment  54  may also be a local host (e.g., a user&#39;s own personal computer), from which the user obtains a wireless download of music or other media files. 
   A perspective view of an embodiment of handheld electronic device  18  is shown in  FIG. 4 . In the example of  FIG. 4 , handheld electronic device  18  has been provided with a clickwheel-type user input device for interface  34 . The housing of device  18  in the example of  FIG. 4  has an upper case portion  60  and a lower case portion  58 . Portions  58  and  60  may be formed from any suitable materials, such as plastic or other dielectrics, metal or other conductors, etc. With one suitable arrangement, upper case portion  60  is a plastic cap formed from a plastic based on acrylonitrile-butadiene-styrene copolymers (sometimes referred to as ABS plastic) and lower case portion  58  is based on stamped  304  stainless steel. This is merely illustrative. For example, the housing of device  18  may be formed substantially from plastic or other dielectrics, substantially from metal or other conductors, or from any other suitable material or combinations of materials. 
   To enhance antenna performance, the antenna structures of wireless communications adapter  36  may make use of a parasitic antenna element in handheld electronic device  18 . The parasitic antenna element in handheld electronic device  18  may be formed from any suitable conductive structures in handheld electronic device  18 , including battery structures, printed circuit board structures (e.g., a ground plane formed from a planar circuit board ground conductor), and housing structures (e.g., all or part of the housing of device  18 , such as upper and/or lower housing portions  58  and  60  of  FIG. 4 ). In general, the parasitic antenna element in handheld electronic device  18  may be formed from any combination of these structures. An arrangement in which the parasitic antenna element in handheld electronic device  18  is formed from a conductive housing portion (some or all of the case) of handheld electronic device  18  is described herein as an example. 
   A cross-sectional side view of an embodiment of an illustrative wireless communications adapter  36  and handheld electronic device  18  is shown in  FIG. 5 . As shown in  FIG. 5 , wireless communications adapter  36  may have housing  62 . Housing  62  may formed from a plastic such as ABS plastic, other dielectric materials, or any other suitable material. An advantage to forming housing  62  at least partially from a dielectric is that this allows radio-frequency wireless signals to be readily transmitted from and received by the antenna structures within wireless communications adapter  36 . 
   Wireless communications adapter  36  may have printed circuit board  64 . Resonating antenna element  70  may be mounted on board  64 . Board  64  may contain a planar ground structure such as ground plane  66 . Resonating antenna element  70  may be formed from any suitable antenna structure. With one suitable arrangement, resonating element  70  is formed from a discrete surface mount antenna such as a helical chip antenna in which helical antenna structure  72  is surrounded by a ceramic case. An illustrative chip antenna that may be used for resonating element  70  is Panasonic Part No. 5-058, available from Matsushita Electric Industrial Co., Ltd. Resonating element  70 , together with ground plane  66  and a parasitic antenna element formed from conductive housing portion  58  of device  18  (and, if desired, a conductive upper housing portion or other suitable conductive structures in handheld electronic device  18 ) are used to form the antenna for wireless communications adapter  36 . 
   Ground plane  66  may be formed from one or more conductive layers in a multilayer printed circuit board. Other layers in the printed circuit board may be used to form interconnects for interconnecting circuitry such as electrical components  68  that are mounted to printed circuit board  64 . Electrical components  68  may include integrated circuits such as a transceiver integrated circuit, a power amplifier integrated circuit, a digital signal processor or microprocessor integrated circuit, and application specific integrated circuits. Electrical components  68  may also include an oscillator crystal and passive components such as capacitors, inductors, and resistors (e.g., components that form an impedance matching network for the antenna). Ground plane  66  may form a ground for the electrical components  68  and may sometimes be referred to as digital ground. Ground pins of electrical components  68  may be electrically connected to ground plane  66  through interconnects formed in printed circuit board  64 . 
   Ground plane  66  may be formed in a portion of printed circuit board  64  that is laterally separated from chip antenna  70  (e.g., by 2 mm or several millimeters or more in lateral dimension  102  and the lateral direction that is into the page of  FIG. 5 ). Providing sufficient separation between chip antenna  70  and ground plane  66  helps to improve antenna efficiency. Good grounding for electrical components  68  may be provided by ensuring that ground plane  66  underlies most or all of the components mounted to board  64 . 
   Signal lines on board  64  are electrically connected to connector pins at end  78  of printed circuit board  63 . These connector pins form the active signal paths for connector  37 . Shield or shell  74  forms an outer sheath portion for the connector  37 . As shown by interconnect paths  80  in  FIG. 5 , the digital ground formed from ground plane  66  may be electrically connected to some of the connector pins. Any suitable number of connector pins  82  may be connected to ground plane  66 . For example, one, two, or three or more pins  82  may be connected to ground plane  66 . With one suitable arrangement, there may be 30 pins  82  associated with each of connectors  37  and  30 , nine of which are connected to ground plane  66  in adapter  36 . Because there are generally multiple pins associated with connectors  37  and  30 , connector  37  and mating connector  30  on the handheld electronic device are sometimes referred to as multipin connectors. 
   Connector shield  74  is sometimes referred to as the chassis ground for wireless communications adapter  36 . As shown in  FIG. 5 , connector shield  74  may be connected to ground plane  66  using resistor  76 . Resistor  76  may be, as an example, a 1 kΩ resistor. When connector  37  is inserted into port  30  in direction  84 , shield  74  becomes electrically connected to shield  88  of port connector  30 . Shield  88  may be electrically connected to conductive housing  58  using metal braid  100  or other suitable conductive path. Metal braid  100  may be connected to shield  88  and housing  58  using conductive adhesive (as an example). Although shields  74  and  88  are electrically connected to each other and to conductive housing portion  58 , the presence of resistor  76  ensures that shields  74  and  88  and conductive housing portion  58  are not shorted to ground plane  66 . 
   Conductive housing portion  58  (and shields  74  and  88 ) form a parasitic antenna element that is near-field radio-frequency coupled with ground plane  66  and chip antenna  70 . If the resistance of resistor  76  is extremely low (e.g., 0.1 ohm), shield  74  and ground plane  66  are effectively shorted together. In this situation, housing  58  will generally not perform as a satisfactory parasitic antenna element. Moreover, if the resistance of resistor  76  is too low, the circuitry mounted to board  64  of wireless communications adapter  36  may be susceptible to damage due to electrostatic discharge events (e.g., when a user releases static charge by touching shield  74 ). It may also be desirable to ensure that the resistance of resistor  76  is not too high, so that the voltage on ground  66  is allowed to equilibrate with the voltage on shield  74  and the chassis ground of handheld electronic device  18  (e.g., the ground of device  18  that is formed from shield  88  and case  58 ). 
   Wireless communications adapter  36  may be connected to handheld electronic device  18  by inserting connector  37  into the mating connector  30  on handheld electronic device  18 . When inserted, pins  82  on connector  37  mate with corresponding pins  86  on connector  30 . At the same time, shield  74  (chassis ground on the wireless communications adapter) mates with shield  88  (chassis ground on handheld electronic device  18 ). 
   Handheld electronic device  18  may have printed circuit board  90 . Printed circuit board  90  may lie in the same or substantially same plane as printed circuit board  64  and ground plane  66  (i.e., printed circuit board  64  and its structures may be coplanar with printed circuit board  90  and its structures). Integrated circuits and other electrical components  94  may be mounted to circuit board  90 . Circuit board  90  may have one or more conductive layers that are patterned to form ground plane  92 . Ground plane  92  may form a ground for printed circuit board  90  and may be referred to as the digital ground of handheld electronic device  18 . Ground plane  92  may be connected to at least some of the pins  86  on connector  30 , as indicated schematically by conductive path  96 . This allows the digital grounds on the wireless communications adapter  36  and handheld electronic device  18  to equilibrate during operation. 
   When wireless communications adapter  36  is connected to handheld electronic device  18 , the electrical structure formed by shields  74  and  88  and the conductive portion of the handheld electronic device housing form a parasitic antenna element for the antenna of wireless communications adapter  36  that improves antenna performance. The case of the handheld device (with and without shields  74  and  88  of connectors  37  and  30 ) may therefore sometimes be referred to as the antenna&#39;s parasitic element or ground extension. In operation, the parasitic element formed by conductive portions of the handheld electronic device housing such as conductive housing portion  58  is near-field coupled to ground plane  66 , without being electrically shorted to ground plane  66 , which helps to enhance the efficiency and broaden the bandwidth of the antenna. 
   For satisfactory antenna operation, the dimensions of ground plane  66  and the parasitic antenna element formed from the housing should have appropriate sizes and should be placed at appropriate spatial locations relative to each other. In a typical scenario, the ground plane  66  is a planar structure that is laterally spaced at least several millimeters from chip antenna  70  (i.e., the closest edge of ground plane  66  is separated from the closest portion of chip antenna  70  by several millimeters in a first lateral dimension that is oriented into the page of  FIG. 5  and in a second lateral dimension that is oriented along the page of  FIG. 5  in direction  102 ). 
   Link  16  of  FIG. 1  may be formed using any suitable communications frequency band. With one suitable arrangement, link  16  may be a 2.4 GHz link, such as a Bluetooth® or IEEE 802.11 link (WiFi) or a custom link in the same general frequency range (e.g., a frequency range of about 2.4-2.7 GHz). In these types of situations, the free space wavelength of the radio-frequency signals that are being conveyed between wireless communications adapter  36  and other equipment over link  16  will be about 12 cm. When radio-frequency signals are in relatively close proximity to handheld device  18  and structures such as printed circuit board  64  of wireless communications adapter  36 , the size of one wavelength is reduced by a factor approximately equal to the square root of the effective dielectric constant (i.e., by about 20-40% for common printed circuit board materials). As a result, one wavelength (λ) at 2.4 GHz becomes about 8-9 cm (approximately). 
   The lateral dimensions of the antenna structures (i.e., the width of the structures in dimension  104  of  FIG. 2  and the length of the structures in dimension  102  of  FIG. 2 ) has an impact on antenna performance. It has been determined that antenna performance may be improved significantly (e.g., by 20% to 40%) when the parasitic antenna element has lateral dimensions on the order of about λ/4 to λ/2 (i.e., about 1.5 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm or other suitable lateral dimension) or at least less than about λ (e.g., less than about 9 cm, 10 cm, 11 cm, 12 cm or other suitable lateral dimension) and has a total length plus width (L+W) of less than or equal to about λ (e.g., less than about 9 cm, 10 cm, 11 cm, 12 cm, or other suitable amount). When these optimum size guidelines are not followed, antenna performance may be increased to a lesser extent or may not be substantially increased by the presence of the parasitic antenna element. 
   Ground plane  66  may have lateral dimensions as large as about λ. Because it is generally desirable to minimize the size of external adapters such as wireless communications adapter  36 , it may be advantageous to reduce the size of ground plane  66  (e.g., so that ground plane  66  has lateral dimensions on the order of λ/4). As the performance of antennas may decrease with decreasing size, the improved performance that is provided by the parasitic element formed from the housing of handheld electronic device  18  can be particularly advantageous in situations such as these in which minimal component size is desired. 
   Ground plane  66  need not be rectangular. A perspective view of an illustrative printed circuit board  64  having a non-rectangular planar ground structure  66  is shown in  FIG. 6 . In the example of  FIG. 6 , the shape and position of ground plane  66  is indicated by the dotted line. As shown in  FIG. 6 , there is generally a clearance (e.g., a clearance of about 2-5 mm or more) between the closest edges of ground plane  66  and chip antenna  70 . This separation is desirable for optimum operation of the antenna. Electrical components  68  (e.g., a radio-frequency transceiver integrated circuit and passive components for impedance matching, etc.) may be mounted on board  64  above ground plane  66 . Shield portion  74  of connector  37  forms chassis ground and may be mounted to printed circuit board  64  using any suitable technique (e.g., with a plastic mounting structure, by crimping portions of shield  74  to the protruding edge of board  64 , using adhesive, etc.) 
   A top view of an illustrative embodiment of printed circuit board  66  is shown in  FIG. 7 . In the configuration shown in  FIG. 7 , shield  74  of connector  37  has not yet been mounted to board  66 . As a result, a top set of 15 pins  82  is visible (15 identical pins  82  on the lower side of printed circuit board  66  are not visible). Resistor  76  may be mounted on board  64  in the location shown in  FIG. 7  or any other suitable location. As shown in  FIG. 7 , conductive tab structures  106  on board  64  may be used to form electrical contact to shield  74  ( FIG. 6 ). As described in connection with  FIG. 5 , resistor  76  is preferably used to electrically connect the chassis ground of adapter  36  (i.e., tabs  106  and shield  74  of connector  37 ) to digital ground (ground plane  66 ). 
   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: 20061215
Publication Date: 20091124
Grant Date: 20091124
Priority Date: 20061215
Inventors: WANG SHU-LI
Assignee: APPLE INC
CPC Classifications: [{"code": "H05K1/0243", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/273", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H05K1/0243", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 39526502