PATENT DOCUMENT

Publication Number: US-7764236-B2
Application Number: US-65007207-A
Country: US
Kind Code: B2

Title: Broadband antenna for handheld devices

Abstract:
Broadband antennas and handheld electronic devices with broadband antennas are provided. A handheld electronic device has integrated circuits, a display, and a battery mounted within a housing. The housing has a planar inner surface. A broadband antenna for the handheld electronic device has a ground element and a resonating element. The ground element and resonating element may have the same shape and may have the same size. The ground element and resonating element may lie in a common plane and be separated by a gap that lies in the common plane. The plane in which the ground element and resonating element lie may be parallel to the planar inner surface of the housing. Electronic components such as the integrated circuits, display, and battery can be mounted in the handheld device so that they do not overlap the gap between the ground element and the resonating element.

Claims:
1. An electronic device comprising:
 a non-folding housing having a planar inner surface, wherein the non-folding housing has a height that is measured along a first axis, a width that is measured along a second axis, and a thickness that is measured along a third axis, wherein the third axis is perpendicular to both the first axis and the second axis, and wherein the thickness of the non-folding housing is less than the width and the height of the non-folding housing; 
 a display mounted in the non-folding housing; 
 at least one integrated circuit mounted in the non-folding housing that provides data for the display, that generates data for wireless transmission, and that processes data that is wirelessly received by the electronic device; and 
 wireless communications circuitry mounted in the non-folding housing that communicates with the integrated circuit, wherein the wireless communications circuitry comprises an antenna comprising a ground element and a resonating element that lie in a first plane that is parallel to the planar inner surface, wherein the first plane is parallel to both the first axis and the second axis, wherein the ground element and the resonating element have a common shape and a common size and are separated by a gap lying in the first plane, wherein the antenna has a height that is substantially equal to the height of the non-folding housing and has a width that is substantially equal to the width of the non-folding housing, wherein the display lies in a second plane that is substantially parallel to the first plane, wherein the display has portions that are separated from the resonating element along a first line that is parallel to the third axis, and wherein the display has portions that are separated from the ground element along a second line that is parallel to the third axis, such that the display overlaps the gap. 
 
   
   
     2. The electronic device defined in  claim 1 , wherein the ground element comprises a conductor with at least one curved edge. 
   
   
     3. The electronic device defined in  claim 1  wherein the ground element comprises a triangular conductor. 
   
   
     4. The electronic device defined in  claim 1  wherein the integrated circuit lies above the ground conductor and does not overlap the gap. 
   
   
     5. The electronic device defined in  claim 1  wherein the integrated circuit lies above the ground conductor and does not overlap the gap, the electronic device further comprising a battery, wherein the battery lies above the resonating element and does not overlap the gap. 
   
   
     6. A handheld electronic device comprising:
 a broadband antenna comprising a ground element and a resonating element, wherein the ground element and the resonating element have shapes that are substantially equal, lie in a first plane, and are separated by a gap in the first plane; 
 a battery; 
 a display that has edges; 
 a housing having a height, a width, and a thickness, wherein the thickness of the housing is less than the width and the height of the housing; and 
 at least one integrated circuit, wherein the ground element has edges, wherein the resonating element has edges, and wherein the display is located in a second plane in the handheld electronic device, wherein the second plane is parallel to the first plane and is distinct from the first plane, wherein the edges of the display overlap the edges of the resonating element, wherein the edges of the display overlap the gap, and wherein the broadband antenna has a height that is substantially equal to the height of the housing and has a width that is substantially equal to the width of the housing. 
 
   
   
     7. The handheld electronic device defined in  claim 6  wherein the integrated circuit has edges and wherein the integrated circuit is located in the handheld electronic device above the ground element such that the edges of the integrated circuit do not overlap the edges of the ground element and do not overlap the gap. 
   
   
     8. The handheld electronic device defined in  claim 6  wherein the ground element comprises a ground terminal and wherein the resonating element comprises a feed terminal, the handheld electronic device further comprising an antenna signal path between the integrated circuit and the ground and feed terminals, wherein the antenna signal path comprises at least one ground conductor layer and at least one feed conductor layer separated by at least one dielectric layer. 
   
   
     9. The handheld electronic device defined in  claim 6  wherein the ground element comprises a ground terminal and wherein the resonating element comprises a feed terminal, the handheld electronic device further comprising an antenna signal path between the integrated circuit and the ground and feed terminals, wherein the antenna signal path comprises a coaxial cable. 
   
   
     10. The handheld electronic device defined in  claim 6  wherein the integrated circuit has edges, wherein the integrated circuit is located in the handheld electronic device above the ground element such that the edges of the integrated circuit do not overlap the edges of the ground element and do not overlap the gap, wherein the battery has edges, and wherein the battery is located in the handheld electronic device above the resonating element such that the edges of the battery do not overlap the edges of the resonating element and do not overlap the gap. 
   
   
     11. A handheld electronic device comprising:
 a housing having a rectangular planar inner surface, wherein the housing has a height, a width, and a thickness, wherein the thickness of the housing is less than the width and the height of the housing; 
 a display that has edges and that is mounted in the housing; 
 an integrated circuit; and 
 an antenna comprising a ground element and a resonating element, wherein the ground element and the resonating element have substantially equal sizes, lie in a first plane within the rectangular planar inner surface that is parallel to the rectangular planar inner surface, and are separated by a gap that lies in the first plane, wherein the ground element and the resonating element are formed from foil, wherein the antenna has a height that is substantially equal to the height of the housing and has a width that is substantially equal to the width of the housing, wherein the display is located in a second plane in the handheld electronic device, wherein the second plane is parallel to the first plane and is distinct from the first plane, and wherein the edges of the display overlap the gap. 
 
   
   
     12. The handheld electronic device defined in  claim 11  further comprising:
 a mounting structure formed from printed circuit board material, wherein the ground element and the resonating element are formed on the mounting structure. 
 
   
   
     13. The handheld electronic device defined in  claim 11  wherein the housing is formed from dielectric and wherein the ground element and the resonating element are formed from adhesive-backed metal foil that is attached to the rectangular planar inner surface of the housing. 
   
   
     14. The handheld electronic device defined in  claim 11  wherein the ground element and the resonating element have a common shape, wherein the integrated circuit has edges and wherein the integrated circuit is located in the handheld electronic device above the ground element such that the edges of the integrated circuit do not overlap the gap. 
   
   
     15. The handheld electronic device defined in  claim 11  wherein the antenna exhibits a standing-wave-ratio of less than three from about 800 MHz to about 3000 MHz and wherein the ground element and resonating element comprise metal foil. 
   
   
     16. The handheld electronic device defined in  claim 11  wherein the integrated circuit generates data that is transmitted through the antenna over at least five communications bands in a frequency range extending from 800 MHz to 3000 MHz, wherein the ground element is a metal foil rectangle, and wherein the resonating element is a metal foil rectangle.

Description:
BACKGROUND 
   This invention relates generally to antennas, and more particularly, to broadband antennas in wireless handheld electronic devices. 
   Handheld electronic devices are often provided with wireless capabilities. Handheld electronic devices with wireless capabilities use antennas to transmit and receive radio-frequency signals. For example, cellular telephones contain antennas that are used to handle radio-frequency communications with cellular base stations. Handheld computers often contain short-range antennas for handling wireless connections with wireless access points. Global positioning system (GPS) devices typically contain antennas that are designed to operate at GPS frequencies. 
   As technology advances, it is becoming possible to combine multiple functions into a single device and to expand the number of communications bands a single device can handle. For example, it is possible to incorporate a short-range wireless capability into a cellular telephone. It is also possible to design cellular telephones that cover multiple cellular telephone bands. 
   The desire to cover a wide range of radio frequencies presents challenges to antenna designers. It is typically difficult to design antennas that cover a wide range of communications bands while exhibiting superior radio-frequency performance. This is particularly true when designing antennas for handheld electronic devices where antenna size and shape can be particularly important. 
   As a result of these challenges, conventional handheld devices that need to cover a large number of communications bands tend to use multiple antennas, antennas that are undesirably large, antennas that have awkward shapes, or antennas that exhibit poor efficiency. 
   It would therefore be desirable to be able to provide an improved broadband antenna for a handheld electronic device. 
   SUMMARY 
   In accordance with the present invention, broadband antennas and handheld electronic devices with broadband antennas may be provided. 
   A broadband antenna may have a ground element and a resonating element that are separated by a gap. The ground element and the resonating element may lie in a common plane. With one suitable arrangement, the ground element and the resonating element may have the same shape and same size. Suitable antenna element shapes include squares and other rectangles, triangles, shapes with curved edges such as circles, etc. 
   A handheld electronic device may have a planar front face and a planar inner surface such as a lower inner surface associated with the rear portion of a plastic handheld electronic device housing. The ground element and resonating element may be mounted to the planar inner surface of the housing. For example, the ground element and the resonating element may be formed by attaching portions of adhesive-backed metal foil to the inner surface of the housing. The ground element and the resonating element may also be formed from portions of the housing itself (e.g., when the housing is made of metal). 
   A handheld electronic device in accordance with the present invention may contain electronic components such as integrated circuits, a display, and a battery mounted within a housing. 
   Components such as these may contain substantial conductive portions. For example, integrated circuits may be surrounded with conductive radio-frequency shielding. Liquid crystal displays (LCDs) and other displays may contain planar ground conductors. Batteries may have thin rectangular cases formed from aluminum or other metals. 
   To avoid interfering with the proper operation of the broadband antenna, the electronic components may be mounted within the housing of the handheld electronic device so that the edges of the components do not overlap the gap between the ground element and the resonating element. For example, the edges of the electronic components may lie within the edges of the ground element and within the edges of the resonating element. With one suitable arrangement, the integrated circuit is located above the ground element and the battery and display are located above the resonating element. 
   Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of an illustrative handheld electronic device with a broadband antenna in accordance with the present invention. 
       FIG. 2  is a schematic diagram of an illustrative handheld electronic device and illustrative equipment with which the handheld electronic device may interact wirelessly in accordance with the present invention. 
       FIG. 3  is a schematic diagram of illustrative wireless circuitry for a handheld electronic device in accordance with the present invention. 
       FIG. 4  is a perspective view of an illustrative broadband antenna in accordance with the present invention. 
       FIG. 5  is a graph showing illustrative performance characteristics for an illustrative broadband antenna in accordance with the present invention. 
       FIG. 6  is a diagram showing how an illustrative transceiver module may be electrically connected to an illustrative broadband antenna in a handheld electronic device in accordance with the present invention. 
       FIG. 7  is a perspective view of an illustrative conductive path based on thin films of conductor and dielectric that may be used to interconnect a transceiver with a broadband antenna in accordance with the present invention. 
       FIG. 8  is a perspective view of an illustrative twin lead conductive path that may be used to interconnect a transceiver with a broadband antenna in accordance with the present invention. 
       FIG. 9  is a perspective view of an illustrative coaxial cable that may be used to interconnect a transceiver with a broadband antenna in accordance with the present invention. 
       FIG. 10  is a cross-sectional view of an illustrative conductive path based on a microstrip configuration that may be used to interconnect a transceiver with a broadband antenna in accordance with the present invention. 
       FIG. 11  is a cross-sectional view of an illustrative conductive path based on a stripline configuration that may be used to interconnect a transceiver with a broadband antenna in accordance with the present invention. 
       FIG. 12  is a cross-sectional side view of an illustrative broadband antenna connected to a circuit board on which integrated circuits have been mounted in accordance with the present invention. 
       FIG. 13  is a cross-sectional side view of an illustrative spring-loaded pin that may be used to make electrical connections between a broadband antenna and circuit board in an arrangement of the type shown in  FIG. 12  in accordance with the present invention. 
       FIG. 14  is a plan view of an illustrative broadband antenna having triangular antenna elements in accordance with the present invention. 
       FIG. 15  is a plan view of an illustrative broadband antenna having rounded antenna elements in accordance with the present invention. 
       FIG. 16  is a plan view of an illustrative broadband antenna having circular antenna elements in accordance with the present invention. 
       FIG. 17  is a plan view of an illustrative broadband antenna having elements of different shapes in accordance with the present invention. 
       FIG. 18  is a plan view of an illustrative broadband antenna having rectangular elements of somewhat different sizes in accordance with the present invention. 
       FIG. 19  is a perspective view of an illustrative broadband antenna formed from portions of a metal case in accordance with the present invention. 
       FIG. 20  is a cross-sectional view of an illustrative broadband antenna mounted to a case of a handheld electronic device in accordance with the present invention. 
       FIG. 21  is a cross-sectional side view of an illustrative broadband antenna in a handheld electronic device in accordance with the present invention. 
       FIG. 22  is a cross-sectional side view of another illustrative broadband antenna in a handheld device in accordance with the present invention. 
       FIG. 23  is a plan view of an illustrative layout that may be used when locating handheld electronic device components relative to elements in a broadband antenna in accordance with the present invention. 
       FIG. 24  is a plan view of another illustrative layout that may be used when locating handheld electronic device components relative to elements in a broadband antenna in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   An illustrative portable electronic device in accordance with the present invention is shown in  FIG. 1 . Portable electronic devices such as illustrative portable electronic device  10  may be small portable computers such as those sometimes referred to as ultraportables. Portable devices may also be somewhat smaller devices. Examples of smaller portable devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. With one particularly suitable arrangement, the portable electronic devices are handheld electronic devices. The use of handheld devices is generally described herein as an example, although any suitable electronic device may be used 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. The handheld devices of the invention may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid handheld devices include a cellular telephone that includes media player functionality, a gaming device that includes a wireless communications capability, a cellular telephone that includes game and email functions, and a handheld device that receives email, supports mobile telephone calls, and supports web browsing. These are merely illustrative examples. Device  10  may be any suitable portable or handheld electronic device. 
   Device  10  includes housing  12  and includes at least one antenna of a type that is sometime referred to as a broadband antenna. Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, wood, glass, ceramics, metal, or other suitable materials, or a combination of these materials. In some situations, case  12  may be a dielectric or other low-conductivity material, so that the operation of conductive antenna elements that are located in proximity to case  12  is not disrupted. In other situations, case  12  may be formed from metal elements that serve as antenna elements for the broadband antenna. 
   The broadband antenna in device  10  may have a ground element (sometimes called a ground) and a resonant element (sometimes called a radiating element or antenna feed element). Antenna terminals, which are sometimes referred to as the antenna&#39;s ground and feed terminals are electrically connected to the antenna&#39;s ground and resonant element, respectively. 
   Handheld electronic device  10  may have input-output devices such as a display screen  16 , buttons such as button  23 , user input control devices  18  such as button  19 , and input-output components such as port  20  and input-output jack  21 . Display screen  16  may be, for example, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a plasma display, or multiple displays that use one or more different display technologies. As shown in the example of  FIG. 1 , display screens such as display screen  16  can be mounted on front face  22  of handheld electronic device  10 . If desired, displays such as display  16  can be mounted on the rear face of handheld electronic device  10 , on a side of device  10 , on a flip-up portion of device  10  that is attached to a main body portion of device  10  by a hinge (for example), or using any other suitable mounting arrangement. 
   A user of handheld device  10  may supply input commands using user input interface  18 . User input interface  18  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  16 ), or any other suitable interface for controlling device  10 . Although shown schematically as being formed on the top face  22  of handheld electronic device  10  in the example of  FIG. 1 , user input interface  18  may generally be formed on any suitable portion of handheld electronic device  10 . For example, a button such as button  23  (which may be considered to be part of input interface  18 ) or other user interface control may be formed on the side of handheld electronic device  10 . Buttons and other user interface controls can also be located on the top face, rear face, or other portion of device  10 . If desired, device  10  can be controlled remotely (e.g., using an infrared remote control, a radio-frequency remote control such as a Bluetooth remote control, etc.). 
   Handheld device  10  may have ports such as bus connector  20  and jack  21  that allow device  10  to interface with external components. Typical ports include power jacks to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data ports to exchange data with external components such as a personal computer or peripheral, audio-visual jacks to drive headphones, a monitor, or other external audio-video equipment, etc. The functions of some or all of these devices and the internal circuitry of handheld electronic device  10  can be controlled using input interface  18 . 
   Components such as display  16  and user input interface  18  may cover most of the available surface area on the front face  22  of device  10  (as shown in the example of  FIG. 1 ) or may occupy only a small portion of the front face  22 . Because electronic components such as display  16  often contain large amounts of metal (e.g., as radio-frequency shielding), the location of these components relative to the antenna elements in device  10  should generally be taken into consideration. Suitably chosen locations for the antenna elements and electronic components of the device will allow the antenna of handheld electronic device  10  to function properly without being disrupted by the electronic components. 
   A schematic diagram of an illustrative handheld electronic device of the type that may contain a broadband antenna is shown in  FIG. 2 . Handheld device  10  may be a mobile telephone, a mobile telephone with media player capabilities, a handheld computer, a remote control, a game player, a global positioning system (GPS) device, a combination of such devices, or any other suitable portable electronic device. 
   As shown in  FIG. 2 , handheld device  10  may include storage  34 . Storage  34  may include one or more different types of storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or electrically-programmable-read-only memory), volatile memory (e.g., battery-based static or dynamic random-access-memory), etc. 
   Processing circuitry  36  may be used to control the operation of device  10 . Processing circuitry  36  may be based on a processor such as a microprocessor and other suitable integrated circuits. 
   Input-output devices  38  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Display screen  16  and user input interface  18  of  FIG. 1  are examples of input-output devices  38 . 
   Input-output devices  38  can include user input-output devices  40  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . Display and audio devices  42  may include liquid-crystal display (LCD) screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
   Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, antennas, such as a broadband antenna of the type described in connection with  FIG. 1 , and, if desired, additional antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
   Device  10  can communicate with external devices such as accessories  46  and computing equipment  48 , as shown by paths  50 . Paths  50  may include wired and wireless paths. Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content). Computing equipment  48  may be a server from which songs, videos, or other media are downloaded over a cellular telephone link or other wireless link. Computing equipment  48  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. 
   The wireless communications devices  44  may be used to cover communications frequency bands such as the cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, the global positioning system (GPS) band at 1575 MHz, data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System), the WiFi® (IEEE 802.11) band at 2.4 GHz, and the Bluetooth® band at 2.4 GHz. These are merely illustrative communications bands over which wireless devices  44  may operate. Additional bands are expected to be deployed in the future as new wireless services are made available. Wireless devices  44  may be configured to operate over any suitable band or bands to cover any existing or new services of interest. If desired, multiple antennas may be provided in wireless devices  44  to cover more bands or one or more antennas may be provided with wide-bandwidth resonating elements to cover multiple communications bands of interest. An advantage of using a broadband antenna design that covers multiple communications bands of interest is that this type of approach makes it possible to reduce device complexity and cost and to minimize the amount of a handheld device that is allocated towards antenna structures. 
   A broadband design may be used for one or more antennas in wireless devices  44  when it is desired to cover a relatively larger range of frequencies without providing numerous individual antennas or using a tunable antenna arrangement. If desired, a broadband antenna design may be made tunable to expand its bandwidth coverage or may be used in combination with additional antennas. In general, however, broadband designs tend to reduce or eliminate the need for multiple antennas and tunable configurations. 
   Illustrative wireless communications devices  44  that are based on a broadband antenna arrangement are shown in  FIG. 3 . As shown in  FIG. 3 , wireless communications devices  44  include at least one broadband antenna  62 . Data signals that are to be transmitted by device  10  may be provided to baseband module  52  (e.g., from processing circuitry  36  of  FIG. 2 ). Baseband module  52  may provide data to be transmitted to transmitter circuitry within transceiver circuits  54 . The transmitter circuitry may be coupled to power amplifier circuitry  56  via path  55 . 
   During data transmission, power amplifier circuitry  56  may boost the output power of transmitted signals to a sufficiently high level to ensure adequate signal transmission. Radio-frequency (RF) output stage  57  may contain radio-frequency switches and passive elements such as duplexers and diplexers. The switches in the RF output stage  57  may, if desired, be used to switch devices  44  between a transmitting mode and a receiving mode. Duplexer and diplexer circuits and other passive components in RF output stage may be used to route input and output signals based on their frequency. 
   Matching circuit  60  may include a network of passive components such as resistors, inductors, and capacitors and ensures that broadband antenna  62  is impedance matched to the rest of the circuitry  44 . Wireless signals that are received by antenna  62  are passed to receiver circuitry in transceiver circuitry  54  over a path such as path  64 . 
   An illustrative arrangement that may be used for broadband antenna  62  is shown in  FIG. 4 . As shown in  FIG. 4 , antenna  62  may include a ground element  66  and a resonating element  68 . The ground element  66  may have an associated ground terminal such as ground terminal  78 . The ground element and ground terminal  78  are sometimes referred to (alone and collectively) as the ground of the antenna or the ground plane of the antenna. The ground terminal is also sometimes referred to as the negative terminal of the antenna. The resonating element  68  may have an associated terminal such as terminal  80 . Terminal  80  is sometimes referred to as a positive antenna terminal or the antenna&#39;s feed terminal. Resonating element  68  and terminal  80  are also sometimes referred to (alone and collectively) as the feed of the antenna. 
   The ground element  66  and resonating element  68  may be formed on one or more mounting structures such as mounting structure  70 . Mounting structure  70  may be any suitable mounting structure for proving physical support for elements  66  and  68 . Suitable mounting structures include mounting structures formed from circuit board materials, ceramics, glass, plastic, or other dielectrics. The mounting structure  70  may, if desired, be formed from part of housing  12  ( FIG. 1 ). For example, housing  12  may serve as mounting structure  70  or as part of mounting structure  70 . 
   Suitable circuit board materials for mounting structure  70  include paper impregnated with phonolic resin, resins reinforced with glass fibers such as fiberglass mat impregnated with epoxy resin (sometimes referred to as FR-4), plastics, polytetrafluoroethylene, polystyrene, polyimide, and ceramics. Mounting structure  70  may be formed from a combination of any number of these materials or other suitable materials. Mounting structure  70  may be flexible or rigid or may have both flexible and rigid portions. These are merely illustrative examples. In general, antenna components such as resonating element  68  and ground element  66  may be supported using any suitable structure. 
   Ground element  66  and resonating element  68  may be mounted so that they lie in the same plane. The plane in which ground element  66  and resonating element  68  lie may be a plane that lies within or nearly within a plane that contains the surface of mounting structure  70 . For example, as shown in the illustrative arrangement of  FIG. 4 , ground element  66  and resonating element  68  may lie on the surface of a planar mounting structure  70 , so that a common plane contains the ground element, the resonating element, and the surface of mounting structure  70 . 
   A gap  72  may be used to separate ground element  66  and resonating element  68 . In general, the gap  72  may be any suitable size, provided that the radio-frequency bandwidth and frequency coverage goals for broadband antenna  62  are satisfied. With one illustrative arrangement, the ground element  66  and resonating element  68  have lateral dimensions on the orders of several centimeters and gap  72  is several millimeters (e.g., 2-4 mm). Gap  72  may be an air or dielectric gap. An advantage of this type of arrangement is that it allows ground element  66  and resonating element  68  to fit within a conveniently sized handheld electronic device while still being sufficiently large to operate properly without interference from internal electronic components in the handheld electron device. This type of arrangement is, however, merely illustrative. Any suitable gap size and lateral antenna element dimensions may be used if desired. This is, however, merely illustrative. 
   The thickness of ground element  66  and radiating element  68  is typically less than 0.5 mm. The thickness that is used depends on the type of technology used to manufacture elements  66  and  68 . With one suitable arrangement, elements  66  and  68  are formed from adhesive-backed copper foil of less than 0.2 mm in thickness. If elements  66  and  68  are formed by printing or otherwise depositing conductive films on a printed circuit board using the types of operations normally used during semiconductor fabrication processes, elements  66  and  68  may be even thinner. In general, any suitable thicknesses may be used for ground element  66  and radiating element  68 . If desired, ground element  66  and radiating element  68  may have different thicknesses. 
   To avoid electrical interference and ensure that antenna  62  functions optimally, components of handheld electronic device  10  that may significantly influence the radio-frequency behavior of antenna  62  may be located away from gap  72 . By locating electronic components in device  10  so that they do not overlap gap  72 , interference with proper antenna operation is avoided. 
   Consider, as an example, a typical handheld electronic device. A typical handheld electronic device may contain components such as integrated circuits and batteries. Integrated circuits are often electrically shielded with a conductor. Integrated circuits may, for example, be shielded within a conformal sheet of copper. Batteries are often manufactured with a conductive casing formed from aluminum or other metals. Other electronic components such as liquid-crystal displays (LCDs) may also contain large amounts of metal or other conductive structures. 
   To ensure that the operation of antenna  62  is not adversely affected by the presence of the metal or other conductive structures within these electronic components, the electronic components can be located within regions that do not overlap gap  72 , such as the regions located within the boundaries shown by dotted lines  74  and  76 . If electronic components remain within the limits imposed by dotted lines  74  and  76 , the radio-frequency performance of the antenna  62  will not be adversely affected by metal or other conductors overlapping gap  72  and will not be adversely affected by metal or other conductors overlapping the edges of ground element  66  and resonating element  68 . 
   The sizes and shapes of the ground element  66  and resonating element  68  affect the radio-frequency performance of broadband antenna  62 . If desired, ground element  66  and/or resonating element  68  may be constructed so that their heights are larger than their widths. The heights of elements  66  and  68  are taken along the dimension that is parallel to longitudinal axis  82  of antenna  62  and handheld electronic device  10  (i.e., along the longer of the two lateral dimensions of a typical handheld electronic device when viewed from the front). With this type of arrangement, ground element  66  has height h 1  that is larger than width w 1 . Similarly, height h 2  of resonating element  68  is greater than width w 2  of resonating element  68 . Because the heights of elements  66  and  68  are greater than their widths, elements  66  an  68  have a greater-than-unity aspect ratio (h/w). The greater-than-unity aspect ratio of elements  66  and  68  tends to make the antenna  62  vertically polarized when device  10  is held vertically in a user&#39;s hand. Vertically-polarized handheld electronic device antenna arrangements can be advantageous for communicating with vertically-polarized base stations. The use of greater-than-unity aspect ratios for ground element  66  and resonating element  68  are merely illustrative. Any suitable aspect ratios may be used for ground element  66  and resonating element  68  if desired. 
   In the example of  FIG. 4 , elements  66  and  68  have the same size. In particular, heights h 1  and h 2  are equal, widths w 1  and w 2  are equal, and areas A 1 =h 1 ×w 1  and A 2 =h 2 ×w 2  of the antenna elements  66  and  68 , respectively, are equal. Because areas A 1  and A 2  are the same, antenna  62  exhibits a wide and relatively flat bandwidth. If desired, the sizes of elements  66  and  68  may be made unequal. For example, the ratio of the antenna element areas may be in the range of between 0.95 and 1.05 (as an example), may be in the range of between 0.9 and 1.1 (as another example), may be in the range of between 0.8 and 1.2 (as yet another example), etc. Care should be taken, however, to avoid making the respective sizes of the ground element  66  and resonating element  68  too different. If, as an example, the area of the resonating element  68  (A 2 ) is only 10% of the area of ground element  66  (A 1 ), the antenna  62  may begin to behave as an asymmetric dipole. In this situation, the antenna&#39;s frequency response may exhibit “peaks” that cover certain bands (e.g., a lower band and an upper band), rather than exhibiting a desirable relatively flat and broad frequency characteristic. 
   One way to characterize the performance of broadband antenna  62  involves the use of a standing-wave-ratio plot. The standing-wave ratio (SWR) of an antenna is a measure of the antenna&#39;s ability to efficiently transmit radio waves. Standing wave ratios R of less than about 3 are generally acceptable. A graph plotting an illustrative standing-wave-ratio versus frequency characteristic for an illustrative broadband antenna is shown in  FIG. 5 . In the example of  FIG. 5 , the ratio R is 3 or less. Solid line  84  shows the standing-wave ratio for illustrative antenna  62  versus frequency. The plot of  FIG. 5  illustrates the type of frequency response that a broadband antenna of the general type shown in  FIG. 4  can achieve. When implementing an antenna, the frequency range, the standing-wave-ratio flatness, and the maximum standing-wave-ratio (R in the plot of  FIG. 5 ) that are achieved by the antenna depend on a variety of factors, such as antenna conductor material, antenna shape, antenna size, gap size, substrate material, electronic component placement, etc. 
   As shown in  FIG. 5 , antenna  62  can cover a frequency range of about 800 MHz to about 3000 MHz (as an example). In this frequency range, the SWR level of the antenna never rises above R (e.g., 3.0, 2.5, 2.0 or other suitable level). If the ratio of antenna element areas were to become too large (e.g., if ground element  66  were to be 10 times the size of resonating element  68 ), the antenna would behave as an asymmetric dipole and would have a frequency response characterized by dashed-dotted line  86 . The antenna would therefore have a frequency range (e.g., a range about frequency  88 ), in which the SWR performance of the antenna is unacceptable (i.e., well above acceptable standing-wave ratio R). Elements  66  and  68  may be constructed with lateral dimensions on the order of λ 0 /2, where an approximate location for a suitable value of λ 0  is shown on the frequency axis of the graph of  FIG. 5 . 
   Because antenna  62  exhibits a relatively flat frequency response from 800 MHz to 3000 MHz, antenna  62  is able to cover desirable communications frequency bands such as the 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), the global positioning system (GPS) band at 1575 MHz, data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System), the WiFi® (IEEE 802.11) band at 2.4 GHz, and the Bluetooth® band at 2.4 GHz. These bands and other suitable bands are examples of bands that can be covered by antenna  62  if desired. As additional bands of interest are added through deployment of future services, these bands may also be handled by antenna  62 . 
   As described in connection with  FIG. 4 , it may be desirable to place integrated circuits and other electronic components of handheld electronic device in a position within handheld electronic device that avoids overlap with gap  72  and that avoids creating protrusions of the electronic components over the edges of ground element  66  and radiating element  68  (i.e., the edges adjacent to gap  72  and the non-gap edges of elements  66  and  68 ). A schematic plan view of an illustrative handheld device showing how electronic components may be placed so that they remain within the outer perimeter of the antenna elements is shown in  FIG. 6 . 
   As shown in  FIG. 6 , handheld electronic device  10  has ground element  66  and radiating element  68 , whose positions are represented by dotted lines. Electronic components  90  and  118  may include a transceiver module containing a power amplifier  56  and transceiver circuitry such as transceiver circuits  54  of  FIG. 3  (e.g., receiver  94  and transmitter  92 ). The transceiver module may have a ground terminal  96  and a feed terminal  98 , which are electrically connected to ground terminal  78  and feed terminal  80  of elements  66  and  68  via antenna signal path  100 . Because electronic components  90  do not protrude over edges  104 ,  106 ,  108 , or  110  of ground element  66 , because electronic components  118  do not extend beyond edges  110 ,  112 ,  114 , and  116  of resonating element  68 , and because none of the electrical components are overlaid on top of the gap  72 , the radio-frequency performance of the broadband antenna will not be adversely affected by the conductive materials in the electrical components. 
   Antenna signal path  100  may be formed using any suitable radio-frequency signal path arrangement. With one illustrative arrangement, path  100  may be formed from a length of coaxial cable. If desired, path  100  may be formed from layered structures of conductor and dielectric. These are merely illustrative arrangements for path  100 . Any suitable path structure may be used for path  100  if desired. 
   Illustrative structures that may be used for paths such as path  100  of  FIG. 6  are shown in  FIGS. 7-11 . An illustrative microstrip path is shown in  FIG. 7 . Path  100  of  FIG. 7  has a lower conductor  120 , a dielectric  122 , and an upper conductor  124 . Path  100  of  FIG. 7  may be formed as a freestanding path (e.g., using a flexible dielectric such as polyimide) or may be formed as part of another structure (e.g., mounting structure  70 ). Any suitable conductive materials may be used for upper and lower conductors  124  and  120 . In general, high-conductivity materials are beneficial, because high-conductivity materials reduce antenna losses. Lower conductor  120  may be ground and may be connected between module terminal  96  and antenna terminal  78  in  FIG. 6 . Upper conductor  122  may be the antenna&#39;s feed and may be connected between module terminal  98  and antenna terminal  80 . With one suitable arrangement, lower conductor  120  and upper conductor  124  are formed from a metal such as copper. Dielectric layer  122  may be formed from a flexible or rigid circuit board material (if desired). Suitable materials for dielectric layer  122  include paper impregnated with phonolic resin, resins reinforced with glass fibers such as fiberglass mat impregnated with epoxy resin (e.g., FR-4), plastics, polytetrafluoroethylene, polystyrene, polyimide, and ceramics. 
   In the arrangement of  FIG. 8 , path  100  has two wire conductors  126  and  128  separated by a dielectric  130  (e.g., plastic). Conductors  126  and  138  may be, as an example, braided or solid copper. Paths of the type shown in  FIG. 8  are sometimes referred to as twinlead paths. 
     FIG. 9  shows how a coaxial cable can be used to form path  100 . The cable has inner conductor  132 , outer conductor  133 , and dielectric  134 . With one suitable arrangement, inner conductor  132  is formed from solid copper wire. Outer conductor  133  may be formed from braided copper filaments. Dielectric  134  may be formed from polyethylene or polytetrafluoroethylene (as an example). 
   A side view of an illustrative path of the general type shown in  FIG. 7  is shown in  FIG. 10 . As shown in  FIG. 10 , ground conductor  140  and feed conductor  136  in path  100  may be separated by a dielectric  138 . Ground  140  and feed  136  may be formed from copper or other suitable conductive materials. Dielectric  138  may be formed from polyimide (as an example). 
     FIG. 11  shows a side view of an illustrative path in which the feed is sandwiched between two grounds. Path  100  of  FIG. 11  has a central feed conductor  146 . Feed conductor  146  may be separated from ground conductor  150  by dielectric  148 . Feed conductor  146  may be separated from ground conductor  142  by dielectric  144 . Ground conductors  142  and  150  may, as an example, be formed from copper or other highly conductive metals. Dielectric layers  144  and  148  may be formed from polyimide or other suitable insulators. 
   A cross-sectional side view of a portion of an illustrative handheld electronic device containing a broadband antenna is shown in  FIG. 12 . Handheld electronic device portion  152  includes antenna  62  and a mounting structure  154  on which electrical components  90  are mounted. Electrical components  90  may be, for example, integrated circuits. Mounting structure  154  may be formed from any suitable material such as circuit board material. With one suitable arrangement, mounting structure  154  is formed from a rigid double-sided FR-4 circuit board. 
   Antenna  62  may include a mounting structure  70  formed from a circuit board, a support formed from circuit board materials, the housing of a handheld electronic device, or other suitable structures. Antenna ground element  66  and resonating element  68  may be formed on top of the upper surface of mounting structure  70 . Conductive structures such as spring-loaded pins  158  may be used to make contact between the ground and feed terminals of antenna  62  and conductive paths (e.g., conductive traces) formed on board  154 . With one suitable arrangement, circuit board pads  156  are formed on the lower surface of board  154 . Tips  166  of spring-loaded pins  158  press against pads  156  and form a good ohmic contact. Solder  160  may be used to electrically and mechanically connect pins  158  to the ground and feed terminals of antenna  62 . Vias in board  154  may be used to make electrical contact between traces on the lower surface of board  154  and the upper surface of board  154 . Electronic components  90  may be electrically connected to the upper surface traces (e.g., using solder ball bonding or other suitable electrical interconnection arrangements). 
   A cross-section of an illustrative spring-loaded pin is shown in  FIG. 13 . Pin  158  contains a spring  170  and reciprocating plunger  164 . Spring  170  is compressed between inner surface  172  of pin housing  162  and surface  168  of reciprocating plunger  164 . In operation, the compressed spring biases plunger  164  in direction  174 , so that tip  166  is driven against pads  156  ( FIG. 12 ). 
   The ground element and resonating element of antenna  62  need not be rectangular in shape. For example, the ground element and resonating element may be squares, trapezoids, ovals, shapes with curves, or 5-sided, 6-sided, or n-sided polygons, where n is any suitable integer. 
   An example where ground element  66  and resonating element  68  are triangular in shape is shown in  FIG. 14 . To avoid interference with the radio-frequency performance of antenna  62 , electronic components in device  10  can be placed so that they lie within the boundary of regions  76  and  74  (or within even larger regions within the confines of the edges of elements  66  and  68 ). As shown in  FIG. 15 , ground element  66  and resonating element  68  may be formed using antenna shapes that have curves. The arrangement of  FIG. 16  uses circular ground element  66  and circular resonating element  68 .  FIG. 17  shows how the shapes of the ground element and resonating element need not be the same. The  FIG. 17  example has square ground element  66  and curved half-oval resonating element  68 .  FIG. 18  shows a configuration for antenna  62  in which ground element  66  and resonating element  68  are formed from rectangles of unequal size. This type of arrangement causes the antenna to behave as an asymmetric dipole and, if the sizes are too unequal, can lead to undesirable frequency responses of the type shown by curve  86  in  FIG. 5 . Nevertheless, slightly unequal sizes may be acceptable and in some circumstances may be advantageous in that they produce larger areas  76  in which electronic components may be located. 
   If desired, the ground element and resonating element may be formed using portions of housing  12  (also referred to as case  12 ). This type of configuration is shown in  FIG. 19 . As shown in  FIG. 19 , housing  12  has been electrically divided into upper housing portion  12 - 1  and lower housing portion  12 - 2 . Housing portions  12 - 1  and  12 - 2  may be co-planar as shown in  FIG. 19  (i.e., housing portion  12 - 1  and housing portion  12 - 2  may lie in a common plane that is parallel to the plane of the front face  22  of  FIG. 1  of handheld electronic device  10 ). Housing portions  12 - 1  and  12 - 2  may, as shown in  FIG. 19 , form the rear face of the handheld electronic device. If desired, the housing portions  12 - 1  and  12 - 2  may be substantially the same size and/or substantially the same shape. 
   Housing  12  of  FIG. 19  may be formed of a conducive material. With one suitable arrangement, housing  12  is formed from a metal such as aluminum or stainless steel. The housing may be coated with a thin layer of insulator to avoid interference from human contact. For example, an aluminum case may be anodized to form an insulating layer (e.g., an insulating layer that contains aluminum oxide). 
   Housing portion  12 - 2  forms ground element  66  of antenna  62  and housing portion  12 - 1  forms resonating element  68 . Housing portion  12 - 1  and housing portion  12 - 2  are separated by gap  72  (in the example of  FIG. 19 ). Gap  72  may be filled with a dielectric such as plastic, epoxy, or other suitable non-conductive materials. The use of a strong dielectric helps to form a strong housing  12 . If desired, additional support structures (e.g., strengthening members disposed along longitudinal axis  82 ) may be used to ensure that housing  12  and handheld electronic device  10  have satisfactory structural integrity. 
   A cross-sectional side view of another illustrative antenna structure is shown in  FIG. 20 . In the arrangement shown in  FIG. 20 , antenna  62  has been formed from adhesive-backed foil elements. Ground element  66  is formed from metal foil  178  and resonating element  68  is formed from metal foil  182 . Metal foil portions  178  and  182  may be, for example, copper foil. Copper foil portions  178  and  182  may be backed with adhesive  180  and  184  to attach foil portions  178  and  180  to case  12 . 
     FIG. 21  shows a cross-sectional side view of an illustrative handheld electronic device that contains a variety of electronic components. As described in connection with  FIG. 4 , it may be desirable to ensure that the electronic components do not extend substantially beyond the edges of ground element  66  and resonating element  68 . With this approach, the electronic components may be maintained substantially within the boundaries established by the edges of ground element  66  and resonating element  68 . It may also be desirable to ensure that the electronic components do not overlap gap  72 . By ensuring that no metal surfaces encroach on gap  72 , optimum antenna performance can be maintained. Wires  192  may be used to electrically connect the electronic components of  FIG. 21  together. 
   In the illustrative arrangement of  FIG. 21 , user input interface  18  (e.g., user controls such as buttons), battery  188  (which may include one or more battery cells), and integrated circuits  186  are shown as being aligned with ground element  66 . User input interface  18  may not contain substantial amounts of metal and may be spaced relatively far from the gap between element  66  and  68 , so, if desired, user input interface  18  may overlap with gap  72  somewhat and may extend laterally over the edges of element  66 . Battery  188  typically has a metal casing and integrated circuits  186  typically have metal RF shielding, so with one suitable arrangement, battery  188  and integrated circuits  186  do not overlap gap  72 , as shown in  FIG. 21 . In the illustrative layout of  FIG. 21 , LCD  190  is located above resonating element  68 . LCD  190  may contain large conductive surfaces (e.g., planar ground conductors), so LCD  190  may be located above resonating element  68  without protruding into gap  72 . 
   A cross-sectional side view of another illustrative handheld electronic device containing a variety of electronic components is shown in  FIG. 22 . In the example of  FIG. 22 , user control interface  16  has been formed on the upper surface of device  10 . Integrated circuits  186  may be mounted in device  10  so that the edges of integrated circuits  186  do not extend beyond the edges of ground element  66 . This prevents conductive surfaces such as copper shielding surrounding integrated circuits  186  from protruding into gap  72 . As with the illustrative arrangement of  FIG. 21 , liquid crystal display  190  is located above resonating element  68 . In vertical dimension  194 , LCD  190  is relatively far from antenna  62  (e.g., LCD  190  is above a plane represented by dotted line  196 ). As a result, the conductive portions of LCD  190  may not have as great an impact on antenna performance as electronic components that are located closer to antenna  62  (e.g., components that are located below line  196 ). Because LCD  190  is located farther away from antenna  62  than other components, LCD  190  may, if desired, overlap somewhat with gap  72 . An optional location for LCD  190  is indicated by dashed-dotted line  198 . In general, however, interference can be minimized by ensuring that LCD  190  does not protrude into gap  72 . 
   As shown in the arrangement of  FIG. 22 , battery  198  (which may include one or more individual battery cells), may be located so that it lies above resonating element  68  without extending beyond the edges of resonating element  68 . An advantage of placing battery  188  in the location shown in  FIG. 22  rather than the location shown in  FIG. 21  is that the  FIG. 22  arrangement may allow device  10  to be formed from a thinner case. In the arrangement of  FIG. 21 , battery  188  is stacked on top of integrated circuits  186 , so there may be more thickness in the vicinity of ground element  66  than with the arrangement of  FIG. 22  (in which only integrated circuits  186  are located above ground element  66 ). 
     FIG. 23  shows a plan view of an illustrative arrangement for handheld electronic device  10  in which two portions of battery  188  are located above resonating element  68 , while one portion of battery  188  and integrated circuits  186  are located above ground antenna element  66 . Gap  72  is not covered, so the performance of antenna  62  is not disturbed by the presence of electronic components containing conductive elements (e.g., metal shielding, planar ground structures, etc.). 
   Another possible approach is shown in  FIG. 24 . In  FIG. 24 , LCD  190  and a first portion of battery  188  are located above resonating antenna element  68 , whereas a second portion of battery  188  and integrated circuits  186  are located above ground element  66 . None of the components in  FIG. 24  overlap gap  72  between ground element  66  and resonating element  68 . 
   In general, any suitable components of handheld electronic device  10  can be located above ground elements  66  and  68 . Components may be located so as to permit handheld electronic device  10  to be manufactured to desired dimensions. For example, if it is desired to manufacture a handheld electronic device that is very thin, electronic components can be relatively evenly distributed by using an arrangement of the type shown in  FIG. 22 . If there is a desire for a slightly larger area in which to locate integrated circuits, the area of ground element  66  can be expanded somewhat (e.g., 10%) at the expense of resonating element  68 . Care should be taken, however, to maintain the flat frequency response of antenna  62 , as described in connection with  FIG. 5 . Still other layouts may be used when it is desired to accommodate a particular component (e.g., an LCD screen or a battery of a particular size or shape). 
   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: 20070104
Publication Date: 20100727
Grant Date: 20100727
Priority Date: 20070104
Inventors: HILL ROBERT J.
CABALLERO RUBEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 39593804