PATENT DOCUMENT

Publication Number: US-7864123-B2
Application Number: US-89703307-A
Country: US
Kind Code: B2

Title: Hybrid slot antennas for handheld electronic devices

Abstract:
Handheld electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include an antenna. The antenna may be formed from a ground plane having a dielectric-filled slot that defines a slot antenna structure and having a planar-inverted-F (PIFA) resonating element located above the opening. The slot antenna structure and the PIFA resonating element may both contribute to the performance of the antenna, so that the antenna exhibits the performance of a hybrid PIFA-slot antenna. The PIFA resonating element may contain multiple antenna resonating element branches. The branches may be configured to operate in different communications bands than the slot antenna structure.

Claims:
What is claimed is: 
     
       1. A hybrid handheld electronic device antenna with characteristics of both a planar inverted-F antenna and a slot antenna, comprising:
 a ground plane antenna element having portions that define a dielectric-filled slot associated with the slot antenna, wherein the slot is a closed slot that has a periphery that is completely surrounded by the portions of the ground plane antenna element; and 
 a planar antenna resonating element that is located above the slot and that is associated with the planar inverted-F antenna, wherein the slot antenna is configured to operate in a first communications band, wherein the planar antenna resonating element comprises a first antenna resonating element branch that is configured to operate in a second communications band that is different than the first communications band, and wherein the planar antenna resonating element comprises a second antenna resonating element branch that is configured to operate in a third communications band that is different than the first communications band and the second communications band. 
 
     
     
       2. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz. 
     
     
       3. The hybrid handheld electronic device antenna defined in  claim 1  wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and a Personal Communications Service (PCS) band at 1900 MHz. 
     
     
       4. The hybrid handheld electronic device antenna defined in  claim 1  wherein the second antenna resonating element branch is configured to operate in an Global System for Mobile (GSM) communications band at 850 MHz and an Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       5. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and a Personal Communications Service (PCS) band at 1900 MHz. 
     
     
       6. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and wherein the second antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       7. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz, wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and a Personal Communications Service (PCS) band at 1900 MHz, and wherein the second antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       8. The hybrid handheld electronic device antenna defined in  claim 1  wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and a Personal Communications Service (PCS) band at 1900 MHz and wherein the second antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       9. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz. 
     
     
       10. The hybrid handheld electronic device antenna defined in  claim 1  wherein the first antenna resonating element branch is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and a Personal Communications Service (PCS) band at 1900 MHz. 
     
     
       11. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and wherein the first antenna resonating element branch is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and a Personal Communications Service (PCS) band at 1900 MHz. 
     
     
       12. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and wherein the second antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       13. The hybrid handheld electronic device antenna defined in  claim 1  wherein the slot antenna is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz, wherein the first antenna resonating element branch is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and a Personal Communications Service (PCS) band at 1900 MHz, and wherein the second antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       14. The hybrid handheld electronic device antenna defined in  claim 1  wherein the first antenna resonating element branch is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and a Personal Communications Service (PCS) band at 1900 MHz and wherein the second antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       15. A hybrid handheld electronic device antenna with characteristics of both a planar inverted-F antenna and a slot antenna, comprising:
 a ground plane antenna element having portions that define a dielectric-filled slot associated with the slot antenna, wherein the slot is a closed slot that has a periphery that is completely surrounded by the portions of the ground plane antenna element; 
 a planar antenna resonating element that is located above the slot and that is associated with the planar inverted-F antenna, wherein the slot antenna is configured to operate in a first communications band, wherein the planar antenna resonating element comprises a first antenna resonating element branch that is configured to operate in a second communications band that is different than the first communications band, and wherein the planar antenna resonating element comprises a second antenna resonating element branch that is configured to operate in a third communications band that is different than the first communications band and the second communications band; 
 a first pair of antenna terminals through which a first transmission line conveys radio-frequency signals for the slot antenna; and 
 a second pair of antenna terminals through which a second transmission line that is different than the first transmission line conveys radio-frequency signals for the planar antenna resonating element. 
 
     
     
       16. The hybrid handheld electronic device antenna defined in  claim 15  wherein the planar antenna resonating element comprises a third antenna resonating element branch that is configured to operate in a fourth communications band that is different than the first communications band, the second communications band, and the third communications band, wherein the slot antenna is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz, wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz, wherein the second antenna resonating element branch is configured to operate in a Personal Communications Service (PCS) band at 1900 MHz, and wherein the third antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       17. The hybrid handheld electronic device antenna defined in  claim 15  wherein the planar antenna resonating element comprises a third antenna resonating element branch that is configured to operate in a fourth communications band that is different than the first communications band, the second communications band, and the third communications band, wherein the slot antenna is configured to operate in a Personal Communications Service (PCS) band at 1900 MHz, wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz, wherein the second antenna resonating element branch is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz, and wherein the third antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       18. The hybrid handheld electronic device antenna defined in  claim 15  wherein the planar antenna resonating element comprises a third antenna resonating element branch that is configured to operate in a fourth communications band that is different than the first communications band, the second communications band, and the third communications band, wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz, wherein the third antenna resonating element branch is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz, and wherein the slot antenna is configured to operate in a communications band selected from the group consisting of: a Personal Communications Service (PCS) band at 1900 MHz and a Digital Cellular System (DCS) communications band at 1800 MHz. 
     
     
       19. A hybrid handheld electronic device antenna with characteristics of both a planar inverted-F antenna and a slot antenna, comprising:
 a ground plane antenna element having portions that define a dielectric-filled slot associated with the slot antenna; 
 a planar antenna resonating element that is located above the slot and that is associated with the planar inverted-F antenna, wherein the slot antenna is configured to operate in a first communications band at 2.4 GHz, wherein the planar antenna resonating element comprises a first antenna resonating element branch that is configured to operate in a second communications band that is different than the first communications band, and wherein the planar antenna resonating element comprises a second antenna resonating element branch that is configured to operate in a third communications band that is different than the first communications band and the second communications band; 
 a first terminal connected to a signal conductor in a transmission line that conveys radio-frequency signals between the hybrid handheld electronic device antenna and transceiver circuitry; 
 a ground terminal that is electrically connected to the ground plane antenna element and a ground conductor in the transmission line; 
 a second terminal that is connected to the ground plane antenna element at a location different from the ground terminal; 
 a first antenna conductive path is electrically connected to the first terminal; and 
 a second antenna conductive path is electrically connected to the second terminal, wherein the first antenna conductive path and the second antenna conductive path convey signals between the first terminal and the second terminal. 
 
     
     
       20. The hybrid handheld electronic device antenna defined in  claim 19  wherein the planar antenna resonating element comprises a third antenna resonating element branch that is configured to operate in a fourth communications band that is different than the first communications band, the second communications band, and the third communications band, wherein the first antenna resonating element branch is configured to operate in a Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz, wherein the second antenna resonating element branch is configured to operate in a Digital Cellular System (DCS) communications band at 1800 MHz and a Personal Communications Service (PCS) band at 1900 MHz, and wherein the third antenna resonating element branch that is configured to operate in a Global System for Mobile (GSM) communications band at 850 MHz and a Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     
     
       21. The hybrid handheld electronic device antenna defined in  claim 19  further comprising a tuning element, wherein the first and second antenna conductive paths are coupled together through the tuning element, wherein the first terminal and the ground terminal serve as antenna feed points for the planar-inverted-F antenna, and wherein the ground terminal and the second terminal serve as antenna feed points for the slot antenna. 
     
     
       22. The hybrid handheld electronic device antenna defined in  claim 19  further comprising a capacitor, wherein the first and second antenna conductive paths are coupled together through the capacitor.

Description:
BACKGROUND 
     This invention relates generally to wireless communications circuitry, and more particularly, to wireless communications circuitry for handheld electronic devices. 
     Handheld electronic devices are becoming increasingly popular. Examples of handheld devices include handheld computers, cellular telephones, media players, and hybrid devices that include the functionality of multiple devices of this type. 
     Due in part to their mobile nature, handheld electronic devices are often provided with wireless communications capabilities. Handheld electronic devices may use long-range wireless communications to communicate with wireless base stations. For example, cellular telephones may communicate using cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz. Handheld electronic devices may also use short-range wireless communications links. For example, handheld electronic devices may communicate using the WiFi® (IEEE 802.11) band at 2.4 GHz and the Bluetooth® band at 2.4 GHz. Communications are also possible in data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System). 
     To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to reduce the size of components that are used in these devices. For example, manufacturers have made attempts to miniaturize the antennas used in handheld electronic devices. 
     A typical antenna may be fabricated by patterning a metal layer on a circuit board substrate or may be formed from a sheet of thin metal using a foil stamping process. Many devices use planar inverted-F antennas (PIFAs). Planar inverted-F antennas are formed by locating a planar resonating element above a ground plane. These techniques can be used to produce antennas that fit within the tight confines of a compact handheld device. 
     Although modern handheld electronic devices often need to function over a number of different communications bands, it is difficult to design a compact antenna that functions satisfactorily over a wide frequency range with satisfactory performance levels. For example, when the vertical size of conventional planar inverted-F antennas is made too small in an attempt to minimize antenna size, the bandwidth and gain of the antenna are adversely affected. 
     It would therefore be desirable to be able to provide improved antennas and wireless handheld electronic devices. 
     SUMMARY 
     Handheld electronic devices and wireless communications circuitry for handheld electronic devices are provided. The wireless communications circuitry may include an antenna. The antenna may include a ground plane having a dielectric-filled opening. The dielectric-filled opening may form a slot antenna structure. The antenna may also have a planar inverted-F antenna (PIFA) resonating element that is located above the opening. The PIFA antenna resonating element may contain multiple branches. The branches of the PIFA resonating element may be configured to operate in different communications bands than the slot antenna structure. 
     With one suitable arrangement, the PIFA antenna resonating element contains two branches. The slot antenna structure may be configured to operate in the Digital Cellular System (DCS) communications band at 1800 MHz. The first antenna resonating element branch may be configured to operate in the Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz and the Personal Communications Service (PCS) band at 1900 MHz. The second antenna resonating element branch may be configured to operate in the Global System for Mobile (GSM) communications band at 850 MHz and the Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     With another suitable two-branch arrangement, the slot antenna structure may be configured to operate in the Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz. The first antenna resonating element branch may be configured to operate in the Digital Cellular System (DCS) communications band at 1800 MHz and the Personal Communications Service (PCS) band at 1900 MHz. The second antenna resonating element branch may be configured to operate in the Global System for Mobile (GSM) communications band at 850 MHz and the Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     If desired, the PIFA resonating element structure may have three branches. In an illustrative arrangement of this type, the slot antenna structure may be configured to operate in the Digital Cellular System (DCS) communications band at 1800 MHz. The first antenna resonating element branch may be configured to operate in the Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz. The second antenna resonating element branch may be configured to operate in the Personal Communications Service (PCS) band at 1900 MHz. The third antenna resonating element branch may be configured to operate in the Global System for Mobile (GSM) communications band at 850 MHz and the Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     With another suitable three-branch arrangement, the slot antenna structure may be configured to operate in the Personal Communications Service (PCS) band at 1900 MHz. The first antenna resonating element branch may be configured to operate in the Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz. The second antenna resonating element branch may be configured to operate in the Digital Cellular System (DCS) communications band at 1800 MHz. The third antenna resonating element branch may be configured to operate in the Global System for Mobile (GSM) communications band at 850 MHz and the Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     If desired, a three-branch antenna resonating element arrangement may be used in which the slot antenna structure is configured to operate in a communications band at 2.4 GHz. The first antenna resonating element branch may be configured to operate in the Universal Mobile Telecommunications System (UMTS) communications band at 2170 MHz. The second antenna resonating element branch may be configured to operate in the Digital Cellular System (DCS) communications band at 1800 MHz and the Personal Communications Service (PCS) band at 1900 MHz. The third antenna resonating element branch may be configured to operate in the Global System for Mobile (GSM) communications band at 850 MHz and the Extended Global System for Mobile (EGSM) communications band at 900 MHz. 
     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 an antenna in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative handheld electronic device with an antenna in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an illustrative handheld electronic device with an antenna in accordance with an embodiment of the present invention. 
         FIG. 4  is a perspective view of an illustrative planar inverted-F antenna (PIFA) in accordance with an embodiment of the present invention. 
         FIG. 5  is a cross-sectional side view of an illustrative planar inverted-F antenna in accordance with an embodiment of the present invention. 
         FIG. 6  is an illustrative antenna performance graph for an antenna of the type shown in  FIGS. 4 and 5  in which standing-wave-ratio (SWR) values are plotted as a function of operating frequency in accordance with the present invention. 
         FIG. 7  is a perspective view of an illustrative planar inverted-F antenna in which a portion of the antenna&#39;s ground plane underneath the antenna&#39;s resonating element has been removed in accordance with an embodiment of the present invention. 
         FIG. 8  is a top view of an illustrative slot antenna in accordance with an embodiment of the present invention. 
         FIG. 9  is an illustrative antenna performance graph for an antenna of the type shown in  FIG. 8  in which standing-wave-ratio (SWR) values are plotted as a function of operating frequency. 
         FIG. 10  is a perspective view of an illustrative planar inverted-F antenna in which a portion of the antenna&#39;s ground plane underneath the antenna&#39;s resonating element has been removed and in which the antenna is shown as being fed by two coaxial cable feeds in accordance with an embodiment of the present invention. 
         FIG. 11  is a perspective view of an illustrative antenna that has both PIFA and slot antenna characteristics in accordance with an embodiment of the present invention. 
         FIG. 12  is a top view of an illustrative three-branch multi-arm PIFA resonating element for a hybrid PIFA-slot antenna in accordance with an embodiment of the present invention. 
         FIG. 13  is a graph of an illustrative antenna performance graph for hybrid PIFA-slot antennas in accordance with embodiments of the present invention in which standing-wave-ratio (SWR) values are plotted as a function of operating frequency. 
         FIGS. 14 and 15  are tables showing how illustrative hybrid PIFA-slot antennas with two-branch multi-arm PIFA resonating elements may be configured to handle multiple communications bands in accordance with embodiments of the present invention. 
         FIG. 16 ,  FIG. 17 , and  FIG. 18  are tables showing how illustrative hybrid PIFA-slot antennas with three-branch multi-arm PIFA resonating elements may be configured to handle multiple communications bands in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to wireless communications, and more particularly, to wireless electronic devices and antennas for wireless electronic devices. 
     The wireless electronic devices may be portable electronic devices such as laptop computers or small portable computers of the type that are sometimes referred to as ultraportables. Portable electronic devices may also be somewhat smaller devices. Examples of smaller portable electronic devices include wrist-watch devices, pendant devices, headphone and earpiece devices, and other wearable and miniature devices. With one suitable arrangement, which is sometimes described herein as an example, the portable electronic devices are handheld electronic devices. 
     The handheld devices may be, for example, cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controllers, global positioning system (GPS) devices, and handheld gaming devices. The handheld devices may also be hybrid devices that combine the functionality of multiple 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, has music player functionality and supports web browsing. These are merely illustrative examples. 
     An illustrative handheld electronic device in accordance with an embodiment of the present invention is shown in  FIG. 1 . Device  10  may be any suitable portable or handheld electronic device. 
     Device  10  may have housing  12 . Device  10  may include one or more antennas for handling wireless communications. Embodiments of device  10  that contain one antenna are sometimes described herein as an example. 
     Device  10  may handle communications over multiple communications bands. For example, wireless communications circuitry in device  10  may be used to handle cellular telephone communications in one or more frequency bands and data communications in one or more communications bands. With one suitable arrangement, which is sometimes described herein as an example, the wireless communications circuitry of device  10  is configured to handle data communications in a communications band centered at 2.4 GHz (e.g., WiFi and/or Bluetooth frequencies) and/or data communications in a 3G data band such as the UMTS band. The UMTS band may range from 1920-2170 MHz (sometimes referred to as 2170 MHz). Other data bands may also be supported instead of these data communications bands or in addition to these data communications bands. In configurations with multiple antennas, the antennas may be located at opposite ends of device  10  to reduce interference (as an example). 
     Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including, plastic, glass, ceramics, metal, or other suitable materials, or a combination of these materials. In some situations, housing  12  or portions of housing  12  may be formed from a dielectric or other low-conductivity material, so that the operation of conductive antenna elements that are located in proximity to housing  12  is not disrupted. Housing  12  or portions of housing  12  may also be formed from conductive materials such as metal. An illustrative housing material that may be used is anodized aluminum. Aluminum is relatively light in weight and, when anodized, has an attractive insulating and scratch-resistant surface. If desired, other metals can be used for the housing of device  10 , such as stainless steel, magnesium, titanium, alloys of these metals and other metals, etc. In scenarios in which housing  12  is formed from metal elements, one or more of the metal elements may be used as part of the antenna in device  10 . For example, metal portions of housing  12  may be shorted to an internal ground plane in device  10  to create a larger ground plane element for that device  10 . To facilitate electrical contact between an anodized aluminum housing and other metal components in device  10 , portions of the anodized surface layer of the anodized aluminum housing may be selectively removed during the manufacturing process (e.g., by laser etching). 
     Housing  12  may have a bezel  14 . The bezel  14  may be formed from a conductive material. The conductive material may be a metal (e.g., an elemental metal or an alloy) or other suitable conductive materials. With one suitable arrangement, which is sometimes described herein as an example, bezel  14  may be formed from stainless steel. Stainless steel can be manufactured so that it has an attractive shiny appearance, is structurally strong, and does not corrode easily. If desired, other structures may be used to form bezel  14 . For example, bezel  14  may be formed from plastic that is coated with a shiny coating of metal or other suitable substances. 
     Bezel  14  may serve to hold a display or other device with a planar surface in place on device  10 . As shown in  FIG. 1 , for example, bezel  14  may be used to hold display  16  in place by attaching display  16  to housing  12 . Device  10  may have front and rear planar surfaces. In the example of  FIG. 1 , display  16  is shown as being formed as part of the planar front surface of device  10 . The periphery of the front surface may be surrounded by bezel  14 . If desired, the periphery of the rear surface may be surrounded by a bezel (e.g., in a device with both front and rear displays). 
     Display  16  may be a liquid crystal diode (LCD) display, an organic light emitting diode (OLED) display, or any other suitable display. The outermost surface of display  16  may be formed from one or more plastic or glass layers. If desired, touch screen functionality may be integrated into display  16  or may be provided using a separate touch pad device. An advantage of integrating a touch screen into display  16  to make display  16  touch sensitive is that this type of arrangement can save space and reduce visual clutter. 
     In a typical arrangement, bezel  14  may have prongs that are used to secure bezel  14  to housing  12  and that are used to electrically connect bezel  14  to housing  12  and other conductive elements in device  10 . The housing and other conductive elements form a ground plane for the antenna(s) in the handheld electronic device. A gasket (e.g., an o-ring formed from silicone or other compliant material, a polyester film gasket, etc.) may be placed between the underside of bezel  14  and the outermost surface of display  16 . The gasket may help to relieve pressure from localized pressure points that might otherwise place stress on the glass or plastic cover of display  16 . The gasket may also help to visually hide portions of the interior of device  10  and may help to prevent debris from entering device  10 . 
     In addition to serving as a retaining structure for display  16 , bezel  14  may serve as a rigid frame for device  10 . In this capacity, bezel  14  may enhance the structural integrity of device  10 . For example, bezel  14  may make device  10  more rigid along its length than would be possible if no bezel were used. Bezel  14  may also be used to improve the appearance of device  10 . In configurations such as the one shown in  FIG. 1  in which bezel  14  is formed around the periphery of a surface of device  10  (e.g., the periphery of the front face of device  10 ), bezel  14  may help to prevent damage to display  16  (e.g., by shielding display  16  from impact in the event that device  10  is dropped, etc.). 
     Display screen  16  (e.g., a touch screen) is merely one example of an input-output device that may be used with handheld electronic device  10 . If desired, handheld electronic device  10  may have other input-output devices. For example, handheld electronic device  10  may have user input control devices such as button  19 , and input-output components such as port  20  and one or more input-output jacks (e.g., for audio and/or video). Button  19  may be, for example, a menu button. Port  20  may contain a 30-pin data connector (as an example). Openings  24  and  22  may, if desired, form microphone and speaker ports. Display screen  16  may be, for example, a liquid crystal display (LCD), an organic light-emitting diode (OLED) display, a plasma display, or multiple displays that use one or more different display technologies. In the example of  FIG. 1 , display screen  16  is shown as being mounted on the front face of handheld electronic device  10 , but display screen  16  may, if desired, 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 devices such as button  19  and touch screen  16 . Suitable user input interface devices for handheld electronic device  10  include buttons (e.g., alphanumeric keys, power on-off, power-on, power-off, and other specialized buttons, etc.), a touch pad, pointing stick, or other cursor control device, a microphone for supplying voice commands, or any other suitable interface for controlling device  10 . Although shown schematically as being formed on the top face of handheld electronic device  10  in the example of  FIG. 1 , buttons such as button  19  and other user input interface devices may generally be formed on any suitable portion of handheld electronic device  10 . For example, a button such as button  19  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 port  20 . Port  20 , which may sometimes be referred to as a dock connector, 30-pin data port connector, input-output port, or bus connector, may be used as an input-output port (e.g., when connecting device  10  to a mating dock connected to a computer or other electronic device. Device  10  may also have audio and video jacks that allow device  10  to interface with external components. Typical ports include power jacks to recharge a battery within device  10  or to operate device  10  from a direct current (DC) power supply, data ports to exchange data with external components such as a personal computer or peripheral, audio-visual jacks to drive headphones, a monitor, or other external audio-video equipment, a subscriber identity module (SIM) card port to authorize cellular telephone service, a memory card slot, etc. The functions of some or all of these devices and the internal circuitry of handheld electronic device  10  can be controlled using input interface devices such as touch screen display  16 . 
     Components such as display  16  and other user input interface devices may cover most of the available surface area on the front face of device  10  (as shown in the example of  FIG. 1 ) or may occupy only a small portion of the front face of device  10 . 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 antennas of handheld electronic device  10  to function properly without being disrupted by the electronic components. 
     With one suitable arrangement, the antenna resonating element structures of device  10  are located in the lower end  18  of device  10 , in the proximity of port  20 . An advantage of locating antenna resonating element structures in the lower portion of housing  12  and device  10  is that this places radiating portions of the antenna structures away from the user&#39;s head when the device  10  is held to the head (e.g., when talking into a microphone and listening to a speaker in the handheld device as with a cellular telephone). This reduces the amount of radio-frequency radiation that is emitted in the vicinity of the user and minimizes proximity effects. 
     A schematic diagram of an embodiment of an illustrative handheld electronic device 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 other 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. With one suitable arrangement, processing circuitry  36  and storage  34  are used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. Processing circuitry  36  and storage  34  may be used in implementing suitable communications protocols. Communications protocols that may be implemented using processing circuitry  36  and storage  34  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, protocols for handling 3G data services such as UMTS, cellular telephone communications protocols, etc. 
     Input-output devices  38  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Display screen  16 , button  19 , microphone port  24 , speaker port  22 , and dock connector port  20  are examples of input-output devices  38 . 
     Input-output devices  38  can include user input-output devices  40  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, etc. A user can control the operation of device  10  by supplying commands through user input devices  40 . Display and audio devices  42  may include liquid-crystal display (LCD) screens or other screens, light-emitting diodes (LEDs), and other components that present visual information and status data. Display and audio devices  42  may also include audio equipment such as speakers and other devices for creating sound. Display and audio devices  42  may contain audio-video interface equipment such as jacks and other connectors for external headphones and monitors. 
     Wireless communications devices  44  may include communications circuitry such as radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, passive RF components, one or more antennas, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Device  10  can communicate with external devices such as accessories  46  and computing equipment  48 , as shown by paths  50 . Paths  50  may include wired and wireless paths. Accessories  46  may include headphones (e.g., a wireless cellular headset or audio headphones) and audio-video equipment (e.g., wireless speakers, a game controller, or other equipment that receives and plays audio and video content). 
     Computing equipment  48  may be any suitable computer. With one suitable arrangement, computing equipment  48  is a computer that has an associated wireless access point (router) or an internal or external wireless card that establishes a wireless connection with device  10 . The computer may be a server (e.g., an internet server), a local area network computer with or without internet access, a user&#39;s own personal computer, a peer device (e.g., another handheld electronic device  10 ), or any other suitable computing equipment. 
     The antenna structures and wireless communications devices of device  10  may support communications over any suitable wireless communications bands. For example, wireless communications devices  44  may be used to cover communications frequency bands such as the cellular telephone bands at 850 MHz, 900 MHz, 1800 MHz, and 1900 MHz, data service bands such as the 3G data communications band at 2170 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System), the WiFi® (IEEE 802.11) bands at 2.4 GHz and 5.0 GHz (also sometimes referred to as wireless local area network or WLAN bands), the Bluetooth® band at 2.4 GHz, and the global positioning system (GPS) band at 1550 MHz. The 850 MHz band is sometimes referred to as the Global System for Mobile (GSM) communications band. The 900 MHz communications band is sometimes referred to as the Extended GSM (EGSM) band. The 1800 MHz band is sometimes referred to as the Digital Cellular System (DCS) band. The 1900 MHz band is sometimes referred to as the Personal Communications Service (PCS) band. 
     Device  10  can cover these communications bands and/or other suitable communications bands with proper configuration of the antenna structures in wireless communications circuitry  44 . 
     A cross-sectional view of an illustrative handheld electronic device is shown in  FIG. 3 . In the example of  FIG. 3 , device  10  has a housing that is formed of a conductive portion  12 - 1  and a plastic portion  12 - 2 . Conductive portion  12 - 1  may be any suitable conductor such as aluminum, magnesium, stainless steel, alloys of these metals and other metals, etc. 
     Housing portion  12 - 2  may be formed from a dielectric. An advantage of using dielectric for housing portion  12 - 2  is that this allows a resonating element portion  54 - 1  of antenna  54  of device  10  to operate without interference from the metal sidewalls of housing  12 . With one suitable arrangement, housing portion  12 - 2  is a plastic cap formed from a plastic based on acrylonitrile-butadiene-styrene copolymers (sometimes referred to as ABS plastic). These are merely illustrative housing materials for device  10 . For example, the housing of device  10  may be formed substantially from plastic or other dielectrics, substantially from metal or other conductors, or from any other suitable materials or combinations of materials. 
     Components such as components  52  may be mounted on circuit boards in device  10 . The circuit board structures in device  10  may be formed from any suitable materials. Suitable circuit board materials include paper impregnated with phonolic resin, resins reinforced with glass fibers such as fiberglass mat impregnated with epoxy resin (sometimes referred to as FR-4), plastics, polytetrafluoroethylene, polystyrene, polyimide, and ceramics. Circuit boards fabricated from materials such as FR-4 are commonly available, are not cost-prohibitive, and can be fabricated with multiple layers of metal (e.g., four layers). So-called flex circuits, which are flexible circuit board materials such as polyimide, may also be used in device  10 . 
     Typical components in device  10  include integrated circuits, LCD screens, and user input interface buttons. Device  10  also typically includes a battery, which may be mounted along the rear face of housing  12  (as an example). 
     Because of the conductive nature of components such as these and the printed circuit boards upon which these components are mounted, the components, circuit boards, and conductive housing portions (including bezel  14 ) of device  10  may be grounded together to form an antenna ground plane  54 - 2 . With one illustrative arrangement, ground plane  54 - 2  may conform to the generally rectangular shape of housing  12  and device  10  and may match the rectangular lateral dimensions of housing  12 . 
     Ground plane element  54 - 2  and antenna resonating element  54 - 1  form antenna  54  for device  10 . If desired, other antennas can be provided for device  10  in addition to antenna  54 . Such additional antennas may, if desired, be configured to provide additional gain for an overlapping frequency band of interest (i.e., a band at which antenna  54  is operating) or may be used to provide coverage in a different frequency band of interest (i.e., a band outside of the range of antenna  54 ). 
     Any suitable conductive materials may be used to form ground plane element  54 - 2  and resonating element  54 - 1  in antenna  54 . Examples of suitable conductive materials for antenna  54  include metals, such as copper, brass, silver, and gold. Conductors other than metals may also be used, if desired. In a typical scenario, the conductive structures for resonating element  54 - 1  are formed from copper traces on a flex circuit or other suitable substrate. 
     Components  52  include transceiver circuitry (see, e.g., devices  44  of  FIG. 2 ). The transceiver circuitry may be provided in the form of one or more integrated circuits and associated discrete components (e.g., filtering components). Transceiver circuitry may include one or more transmitter integrated circuits, one or more receiver integrated circuits, switching circuitry, amplifiers, etc. Each transceiver in transceiver circuitry may have an associated coaxial cable or other transmission line that is connected to antenna  54  and over which radio frequency signals are conveyed. In the example of  FIG. 3 , a transmission line is depicted by dashed line  56 . 
     As shown in  FIG. 3 , the transmission line  56  may be used to distribute radio-frequency signals that are to be transmitted through the antenna from a transmitter integrated circuit  52  or other transceiver circuit to antenna  54 . Path  56  may also be used to convey radio-frequency signals that have been received by antenna  54  to components  52 . A receiver integrated circuit or other transceiver circuitry may be used to process incoming radio-frequency signals that have been conveyed from antenna  54  over one or more transmission lines  56 . 
     Antenna  54  may be formed in any suitable shape. With one suitable arrangement, antenna  54  is based at least partly on a planar inverted-F antenna (PIFA) structure. An illustrative PIFA structure that may be used for antenna  54  is shown in  FIG. 4 . As shown in  FIG. 4 , PIFA structure  54  has a ground plane portion  54 - 2  and a planar resonating element portion  54 - 1 . Antennas are fed using positive signals and ground signals. The portion of an antenna to which the positive signal is provided is sometimes referred to as the antenna&#39;s positive terminal or feed terminal. This terminal is also sometimes referred to as the signal terminal or the center-conductor terminal. The portion of an antenna to which the ground signal is provided may be referred to as the antenna&#39;s ground, the antenna&#39;s ground terminal, the antenna&#39;s ground plane, etc. In antenna  54  of  FIG. 4 , feed conductor  58  is used to route positive antenna signals from signal terminal  60  into antenna resonating element  54 - 1 . Ground terminal  62  is shorted to ground plane  54 - 2 , which forms the antenna&#39;s ground. 
     The dimensions of antenna  54  are generally sized to conform to the maximum size allowed by housing  12  of device  10 . Antenna ground plane  54 - 2  may be substantially rectangular in shape having width W in lateral dimension  68  and length L in lateral dimension  66 . The length of antenna  54  in dimension  66  affects its frequency of operation. Dimensions  68  and  66  are sometimes referred to as horizontal dimensions. Resonating element  54 - 1  is typically spaced several millimeters from ground plane  54 - 2  along vertical dimension  64 . The size of antenna  54  in dimension  64  is sometimes referred to as height H of antenna  54 . 
     A cross-sectional view of antenna  54  is shown in  FIG. 5 . As shown in  FIG. 5 , radio-frequency signals may be fed to antenna  54  (when transmitting) and may be received from antenna  54  (when receiving) using signal terminal  60  and ground terminal  62 . In a typical arrangement, a coaxial conductor or other transmission line has its center conductor electrically connected to point  60  and its ground conductor electrically connected to point  62 . 
     A graph of the expected performance of antenna  54  of  FIGS. 4 and 5  is shown in  FIG. 6 . Expected standing wave ratio (SWR) values are plotted as a function of frequency. As shown, there is a reduced SWR value at frequency f 1 , indicating that the antenna performs well in the frequency band centered at frequency f 1 . Antenna  54  may also exhibit a response at harmonic frequencies such as frequency 2f 1 . The harmonic response (if any) may be stronger than the response at f 1  or may be weaker than the response at f 1 . The dimensions of antenna  54  may be selected so that frequencies f 1  and 2f 1  are aligned with a communication bands of interest. The frequency f 1  (and, if any, harmonic frequency 2f 1 ) may be influenced by the length L of antenna  54  in dimension  66 . For operations in a given communications band of interest, it may be advantageous to configure device  10  so that L is approximately equal to one quarter of a wavelength at a frequency f that lies within the communications band. 
     The height H of antenna  54  of  FIGS. 4 and 5  in dimension  64  is limited by the amount of near-field coupling between resonating element  54 - 1  and ground plane  54 - 2 . For a specified antenna bandwidth and gain, it is not possible to reduce the height H without adversely affecting performance. All other variables being equal, reducing height H will cause the bandwidth and gain of antenna  54  to be reduced. 
     As shown in  FIG. 7 , the minimum vertical dimension of antenna  54  can be reduced while still satisfying minimum bandwidth and gain constraints by introducing a dielectric region  70  in the area under antenna resonating element portion  54 - 1 . The dielectric region  70  may be filled with air, plastic, or any other suitable dielectric and represents a cut-away or removed portion of ground plane  54 - 2 . Removed or empty region  70 , which is sometimes referred to as a slot, may be formed from one or more holes in ground plane  54 - 2 . These holes may be square, circular, oval, polygonal, etc. and may extend though adjacent conductive structures in the vicinity of ground plane  54 - 2 . With one suitable arrangement, which is shown in  FIG. 7 , the removed region  70  is rectangular. This is merely illustrative. Slot  70  may have any suitable shape and may be any suitable size. For example, the slot may be a roughly rectangular opening that is slightly smaller than the outermost rectangular outline of resonating element  54 - 1 . Typical resonating element lateral dimensions are on the order of 0.5 cm to 10 cm. 
     The presence of slot  70  reduces near-field electromagnetic coupling between resonating element  54 - 1  and ground plane  54 - 2  and allows height H in vertical dimension  64  to be made smaller than would otherwise be possible while satisfying a given set of bandwidth and gain constraints. For example, height H may be in the range of 1-5 mm, may be in the range of 2-5 mm, may be in the range of 2-4 mm, may be in the range of 1-3 mm, may be in the range of 1-4 mm, may be in the range of 1-10 mm, may be lower than 10 mm, may be lower than 4 mm, may be lower than 3 mm, may be lower than 2 mm, or may be in any other suitable range of vertical displacements above ground plane element  54 - 2 . 
     If desired, the portion of antenna  54  that contains slot  70  may be used to form a slot antenna. The slot antenna structure in antenna  54  may be used at the same time as the PIFA structure. Antenna performance can be improved when operating antenna  54  as a hybrid device so that both its PIFA operating characteristics and its slot antenna operating characteristics are obtained. 
     A top view of a slot antenna is shown in  FIG. 8 . Antenna  72  of  FIG. 8  is typically thin in the dimension into the page (i.e., antenna  72  is planar with its plane lying in the page). Slot  70  is formed in the center of antenna  72 . Slot  70  of  FIG. 8  is shown as being rectangular in shape. This is merely illustrative. Slot  70  may have any suitable shape. 
     Coaxial cable  56  or other transmission line path may be used to feed antenna  72 . In the example of  FIG. 8 , antenna  72  is fed so that center conductor  82  of coaxial cable  56  is connected to signal terminal  80  (i.e., the positive or feed terminal of antenna  72 ) and the outer braid of coaxial cable  56 , which forms the ground conductor for cable  56 , is connected to ground terminal  78 . 
     When antenna  72  is fed using the arrangement of  FIG. 8 , the antenna&#39;s performance is given by the graph of  FIG. 9 . As shown in  FIG. 9 , antenna  72  operates in a frequency band that is centered about center frequency f r . The center frequency f r  is determined by the dimensions of slot  70 . Slot  70  has an inner perimeter P that is equal to two times dimension X plus two times dimension Y (i.e., P=2X+2Y). At center frequency f r , perimeter P is equal to one wavelength. The position of terminals  80  and  78  may be selected for impedance matching. If desired, terminals such as terminals  84  and  86 , which extend around one of the corners of slot  70  may be used to feed antenna  72 , provided that the distance between terminals  84  and  86  is chosen to properly adjust the impedance of antenna  72 . In the illustrative arrangement of  FIG. 8 , terminals  84  and  86  are shown as being respectively configured as a slot antenna ground terminal and a slot antenna signal terminal, as an example. If desired, terminal  84  could be used as a ground terminal and terminal  86  could be used as a signal terminal. Slot  70  is typically an air-filled slot, but may, in general, be filled with any suitable dielectric. 
     An illustrative configuration in which antenna  54  is fed using two coaxial cables (or other transmission lines) is shown in  FIG. 10 . When antenna  54  is fed as shown in  FIG. 10 , both the PIFA and slot antenna portions of antenna  54  are active. As a result, antenna  54  of  FIG. 10  operates in a hybrid PIFA/slot mode. Coaxial cables  56 - 1  and  56 - 2  have inner conductors  82 - 1  and  82 - 2 , respectively. Coaxial cables  56 - 1  and  56 - 2  also each have a conductive outer braid ground conductor. The outer braid conductor of coaxial cable  56 - 1  is electrically shorted to ground plane  54 - 2  at ground terminal  88 . The ground portion of cable  56 - 2  is shorted to ground plane  54 - 2  at ground terminal  92 . The signal connections from coaxial cables  56 - 1  and  56 - 2  are made at signal terminals  90  and  94 , respectively. 
     With the arrangement of  FIG. 10 , two separate sets of antenna terminals are used. Coaxial cable  56 - 1  feeds the PIFA portion of antenna  54 - 1  using ground terminal  88  and signal terminal  90  and coaxial cable  56 - 2  feeds the slot antenna portion of antenna  54  using ground terminal  92  and signal terminal  94 . Each set of antenna terminals therefore operates as a separate feed for the antenna. Signal terminal  90  and ground terminal  88  serve as antenna feed points for the PIFA portion of antenna  54 , whereas signal terminal  94  and ground terminal  92  serve as antenna feed points for the slot portion of antenna  54 . These two separate antenna feeds allow the antenna  54  to function simultaneously using both its PIFA and its slot characteristics. If desired, the orientation of the feeds can be changed. For example, coaxial cable  56 - 2  may be connected to slot  70  using point  94  as a ground terminal and point  92  as a signal terminal or using ground and signal terminals located at other points along the periphery of slot  70 . 
     Each coaxial cable or other transmission line may terminate at a respective transceiver circuit (also sometimes referred to as a radio) or coaxial cables  56 - 1  and  56 - 2  (or other transmission lines) may be connected to switching circuitry that, in turn is connected to one or more radios. When antenna  54  is operated in hybrid PIFA/slot antenna mode, the frequency coverage of antenna  54  and/or its gain at particular frequencies can be enhanced. For example, the additional response provided by the slot antenna portion of antenna  54  may be used to cover one or more frequency bands of interest. 
     If desired, antenna  54  may be fed using a single coaxial cable  56  or other such transmission line. An illustrative configuration for antenna  54  in which a single transmission line is used to simultaneously feed both the PIFA portion and the slot portion of antenna  54  is shown in  FIG. 11 . As shown in  FIG. 11 , antenna  54  has ground plane  54 - 2 . Ground plane  54 - 2  may be formed from conductive structures such as an LCD display, housing wall portions, bezel  14  ( FIG. 1 ), printed circuit boards, etc. Bezel  14  and conductive housing structures may be located around edges  96  of ground plane  54 - 2 . 
     In the illustrative arrangement shown in  FIG. 11 , planar antenna resonating element  54 - 1  has a two-branch F-shaped structure with shorter arm or branch  98  and longer arm or branch  100 . This is merely illustrative. The PIFA portion of antenna  54  may use any suitable resonating element configuration. For example, the PIFA portion of antenna  54  may use a planar resonating element structure of the type shown in  FIG. 4 . Alternatively, a multiarm PIFA resonating element structure may be used that has a different number of branches (e.g., three branches, more than three branches, etc.). The use of a PIFA antenna resonating element structure that is formed with two arms  98  and  100  is shown as an example. 
     In a multiarm arrangement, the dimensions of the branches of the planar resonating element (e.g., the widths and lengths of branches such as arms  98  and  100  in the example of  FIG. 11 ) may be adjusted to tune the frequency coverage of antenna  54 . In general, changes in arm width (the typically narrower lateral dimension of the arm that is perpendicular to its longitudinal axis) will affect the breadth of the antenna resonance associated with the arm, whereas changes in arm length (the typically longer lateral dimension of the arm that is parallel to its longitudinal axis) will affect the position of the antenna resonance. Typical arm widths are on the order of 0.1 cm to 1.0 cm. Typical arm lengths are on the order of 1-10 cm. 
     As shown in  FIG. 11 , arms  98  and  100  may be mounted on a support structure  102 . Support structure  102  may be formed from one or more pieces of plastic (e.g., ABS plastic) or other suitable dielectric structures. The surfaces of structure  102  may be flat or curved. Arms  98  and  100  may be formed directly on support structure  102  or may be formed on a separate structure such as a flex circuit substrate that is attached to support structure  102  (as examples). Arms such as arms  98  and  100  may be straight, curved, bent, etc. 
     With one suitable arrangement, resonating element  54 - 1  is a substantially planar structure that is mounted to an upper surface of support  102 . Resonating element  54 - 1  may be formed by any suitable antenna fabrication technique such as metal stamping, cutting, etching, or milling of conductive tape or other flexible structures, etching metal that has been sputter-deposited on plastic or other suitable substrates, printing from a conducive slurry (e.g., by screen printing techniques), patterning metal such as copper that makes up part of a flex circuit substrate that is attached to support  102  by adhesive, screws, or other suitable fastening mechanisms, etc. 
     A conductive path such as conductive strip  104  may be used electrically connect the resonating element  54 - 1  to ground plane  54 - 2  at terminal  106 . A screw or other fastener at terminal  106  may be used to electrically and mechanically connect strip  104  (and therefore resonating element  54 - 1 ) to edge  96  of ground plane  54 - 2 . Conductive structures such as strip  104  and other such structures in antenna  54  may also be electrically connected to each other using conductive adhesive. 
     A coaxial cable such as cable  56  or other transmission line may be connected to the antenna to transmit and receive radio-frequency signals. The coaxial cable or other transmission line may be connected to the structures of antenna  54  using any suitable electrical and mechanical attachment mechanism. As shown in the illustrative arrangement of  FIG. 11 , mini UFL coaxial connector  110  may be used to connect coaxial cable  56  or other transmission lines to antenna conductor  112 . A center conductor of the coaxial cable or other transmission line is connected to center connector  108  of connector  110 . The outer braid ground conductor of the coaxial cable is electrically connected to ground plane  54 - 2  via connector  110  at point  115  (and, if desired, may be shorted to ground plane  54 - 2  at other attachment points upstream of connector  110 ). 
     Conductor  108  may be electrically connected to antenna conductor  112 . Conductor  112  may be formed from a conductive element such as a strip of metal formed on a sidewall surface of support structure  102 . Conductor  112  may be directly electrically connected to resonating element  54 - 1  (e.g., at portion  116 ) or may be electrically connected to resonating element  54 - 1  through tuning capacitor  114  or other suitable electrical components. The size of tuning capacitor  114  can be selected to tune antenna  54  and ensure that antenna  54  covers the frequency bands of interest for device  10 . 
     Slot  70  may lie beneath resonating element  54 - 1  of  FIG. 11 . The signal from center conductor  108  may be routed to point  106  on ground plane  54 - 2  in the vicinity of slot  70  using a conductive path formed from antenna conductor  112 , optional capacitor  114  or other such tuning components, antenna conductor  117 , and antenna conductor  104 . 
     The configuration of  FIG. 11  allows a single coaxial cable or other transmission line path to simultaneously feed both the PIFA portion and the slot portion of antenna  54 . 
     Grounding point  115  functions as the ground terminal for the slot antenna portion of antenna  54  that is formed by slot  70  in ground plane  54 - 2 . Point  106  serves as the signal terminal for the slot antenna portion of antenna  54 . Signals are fed to point  106  via the path formed by conductive path  112 , tuning element  114 , path  117 , and path  104 . 
     For the PIFA portion of antenna  54 , point  115  serves as antenna ground. Center conductor  108  and its attachment point to conductor  112  serve as the signal terminal for the PIFA. Conductor  112  serves as a feed conductor and feeds signals from signal terminal  108  to PIFA resonating element  54 - 1 . 
     In operation, both the PIFA portion and slot antenna portion of antenna  54  contribute to the performance of antenna  54 . 
     The PIFA functions of antenna  54  are obtained by using point  115  as the PIFA ground terminal (as with terminal  62  of  FIG. 7 ), using point  108  at which the coaxial center conductor connects to conductive structure  112  as the PIFA signal terminal (as with terminal  60  of  FIG. 7 ), and using conductive structure  112  as the PIFA feed conductor (as with feed conductor  58  of  FIG. 7 ). During operation, antenna conductor  112  serves to route radio-frequency signals from terminal  108  to resonating element  54 - 1  in the same way that conductor  58  routes radio-frequency signal from terminal  60  to resonating element  54 - 1  in  FIGS. 4 and 5 , whereas conductive line  104  serves to terminate the resonating element  54 - 1  to ground plane  54 - 2 , as with grounding portion  61  of  FIGS. 4 and 5 . 
     The slot antenna functions of antenna  54  are obtained by using grounding point  115  as the slot antenna ground terminal (as with terminal  86  of  FIG. 8 ), using the conductive path formed from antenna conductor  112 , tuning element  114 , antenna conductor  117 , and antenna conductor  104  as conductor  82  of  FIG. 8  or conductor  82 - 2  of  FIG. 10 , and by using terminal  106  as the slot antenna signal terminal (as with terminal  84  of  FIG. 8 ). 
     The configuration of  FIG. 10  shows that slot antenna ground terminal  92  and PIFA antenna ground terminal  88  may be formed at separate locations on ground plane  54 - 2 . In the configuration of  FIG. 11 , a single coaxial cable may be used to feed both the PIFA portion of the antenna and the slot portion of the antenna. This is because terminal  115  serves as both a PIFA ground terminal for the PIFA portion of antenna  54  and a slot antenna ground terminal for the slot antenna portion of antenna  54 . Because the ground terminals of the PIFA and slot antennas are provided by a common ground terminal structure and because conductive paths  112 ,  117 , and  104  serve to distribute radio-frequency signals to and from the resonating element  54 - 1  and ground plane  54 - 2  as needed for PIFA and slot antenna operations, a single transmission line (e.g., coaxial conductor  56 ) may be used to send and receive radio-frequency signals that are transmitted and received using both the PIFA and slot portions of antenna  54 . 
     If desired, other antenna configurations may be used that support hybrid PIFA/slot operation. For example, the radio-frequency tuning capabilities of tuning capacitor  114  may be provided by a network of other suitable tuning components, such as one or more inductors, one or more resistors, direct shorting metal strip(s), capacitors, or combinations of such components. One or more tuning networks may also be connected to the antenna at different locations in the antenna structure. These configurations may be used with single-feed and multiple-feed transmission line arrangements. 
     Moreover, the location of the signal terminal and ground terminal in antenna  54  may be different from that shown in  FIG. 11 . For example, terminals  115 / 108  and terminal  106  can be moved relative to the locations shown in  FIG. 11 , provided that the connecting conductors  112 ,  117 , and  104  are suitably modified. 
     The PIFA portion of antenna  54  can be provided using a substantially rectangular conductor as shown in  FIG. 4 , or can be provided using other arrangements. For example, resonating element  54 - 1  may be formed from a non-rectangular planar structure, from a planar structure with a rectangular outline that has one or more serpentine conductive structures within the rectangular outline, or from a slotted non-rectangular or slotted rectangular planar structure. 
     With one particularly suitable arrangement, resonating element  54 - 1  may use a multiarm configuration such as the substantially F-shaped conductive element of  FIG. 11  that has arms  98  and  100 . There may be two, three, or more than three resonating element branches in the multiarm resonating element. Such resonating element branches may be straight, serpentine, curved, or may have any other suitable shape. Use of different shapes for the branches or other portions of resonating element  54 - 1  helps antenna designers to tailor the frequency response of antenna  54  to its desired frequencies of operation and to otherwise optimize antenna performance. 
     For example, when it is desired to have a relatively wide frequency response associated with a given antenna branch, the width of that branch may be increased. When it is desired to produce a narrower frequency response, the width of the antenna branch may be reduced. As another example, the position of the antenna response curve that is associated with a particular arm can be adjusted by making adjustments to the length of the arm. In general, peak antenna response for a given branch of the antenna occurs at a frequency at which the length of the antenna branch is equal to one quarter of a wavelength. If it is desired for the resonant peak associated with a given antenna resonating element branch to have a higher frequency, the length of the branch may be decreased. If it is desired for the resonant peak of the antenna resonating element branch to have a lower frequency, the length of the branch may be increased. 
     An illustrative resonating element  54 - 1  that has three branches is shown in  FIG. 12 . Branch  99  has length L 1 . Branch  101  has length L 2 . Branch  103  has length L 3 . Branches such as branches  99 ,  101 , and  103  may be straight, curved, bent, serpentine, etc. An advantage of using bends in the branches of resonating element  54 - 1  (as illustrated by branch  103 ) is that bent branches are compact and help resonating element  54 - 1  to fit within device  10 . 
     A graph showing the performance of an illustrative hybrid PIFA-slot antenna with a multibranch resonating element is shown in  FIG. 13 . In the example of  FIG. 13 , there are four separate frequency response peaks. This is merely illustrative. A hybrid PIFA-slot antenna such as antenna  54  of device  10  may exhibit any suitable number of frequency peaks. 
     The response of the antenna may be adjusted to cover desired communications bands of interest. 
     Consider, as an example, the antenna response peak at frequency f 1 . This peak may be associated with slot  70  or may be associated with a particular branch of a multibranch resonating element such as arm  98  or arm  100  of  FIG. 11  or arm  99 , arm  101 , or arm  103  of  FIG. 12 . If the f 1  peak is associated with slot  70 , the position of the peak may be adjusted to a higher or lower frequency by adjusting the inner perimeter of slot  70 , as indicated by arrows  120  and  122 . For example, the position of the f 1  peak may be shifted to higher frequencies by decreasing the inner perimeter of slot  70  or may be shifted to lower frequencies by increasing the inner perimeter of slot  70 . If the f 1  peak is associated with a branch of resonating element  54 - 1 , the position of the f 1  peak may be shifted to higher frequencies by decreasing the length of the branch or may be shifted to lower frequencies by increasing the length of the branch. 
     As another example, consider the antenna resonance peak at frequency f 2 . This frequency peak may correspond to a particular branch of antenna resonating element  54 - 1 . If it is desired to increase the width of the f 2  peak, the width of the resonating element branch may be increased. In this situation, the f 2  antenna response peak may change from the response indicated by solid line curve  126  to the broader response indicated by dashed line curve  124 . 
     If desired, the frequency peaks from two or more elements of antenna  54  may be aligned. Consider, for example, antenna response peak at frequency f 3 . This peak may be characterized by solid frequency response line  128 . The peak represented by line  128  may be produced by slot  70  or one of the antenna resonating branches. This antenna resonance can be can be strengthened by configuring antenna  54  so that the resonant frequency that is associated with another antenna element coincides with the frequency peak of line  128 . For example, if peak  128  is associated with slot  70 , one of the resonating element branches can be configured so that its response has the same resonant frequency (f 3 ). In this situation, the combined response of the antenna may be increased, as represented by dotted line  130 . Similarly, if peak  128  is associated with one of the branches of the PIFA antenna resonating element in antenna  54 , the strength of peak  128  can be increased by configuring slot  70  or one of the other PIFA branches to resonate at f 3 . 
     When it is desired to broaden a given communications band or it is desired to cover two adjacent bands, antenna  54  can be configured so that different antenna elements produce adjacent frequency response peaks. As shown by solid line  132  in  FIG. 13 , antenna  54  may have an antenna resonance at frequency f 4 . The f 4  antenna resonance may correspond to slot  70  or to one of the branches of PIFA resonating element  54 - 1 . Antenna  54  can be configured to cover an additional nearby frequency f 4 ′, as indicated by dashed-and-dotted line  134 . If, for example, the f 4  peak is being produced by slot  70 , the length of one of the branches of resonating element  54 - 1  can be configured so that the branch produces a resonant peak at f 4 ′. If the f 4  peak is being produced by one of the branches of resonating element  54 - 1 , the length of one of the other branches of resonating element  54 - 1  may be configured to produce a resonant peak at frequency f 4 ′ or the inner perimeter of slot  70  may be configured to produce a resonant peak at f 4 ′. 
     When it is desired to cover multiple adjacent communications bands of interest with antenna  54  (e.g., GSM and EGSM, UMTS and PCS, or DCS and PCS), an appropriate antenna resonance peak may be broadened sufficiently to cover both bands (e.g., by broadening the resonance peak as described in connection with the f 2  peak of  FIG. 13 , by broadening the resonance peak as described in connection with the f 4  resonance peak, by broadening the resonance peak by superimposing a harmonic associated with a lower frequency antenna resonance, or by using more than one of these approaches). 
     If desired, features such as the broadened peak represented by line  124 , the strengthened peak represented by line  130 , and the additional peak represented by line  134  may also be produced by a second harmonic (e.g., the frequency 2f 1  that was described in connection with  FIG. 6 ). Combinations of these approaches may also be used. 
     Illustrative examples of multiband antenna configurations that may be used for antenna  54  of device  10  are set forth in the tables of  FIGS. 14-18 . The tables of  FIGS. 14 and 15  show illustrative configurations for hybrid PIFA-slot antennas with two-branch multi-arm PIFA resonating elements. The tables of  FIGS. 16 ,  17 , and  18  show illustrative configurations for hybrid PIFA-slot antennas with three-branch multi-arm PIFA resonating elements. 
     In the example of  FIG. 14 , antenna  54  has a two-branch resonating element  54 - 1 . The first branch of antenna resonating element  54 - 1  (e.g., branch  98  of  FIG. 11 ) may be configured to cover both the UMTS and PCS communications bands. Slot  70  may be configured to cover the DCS band. The second branch of antenna resonating element  54 - 1  (e.g., branch  100  of  FIG. 11 ) may be configured to cover both the GSM and EGSM bands. An antenna with this type of arrangement may be considered to cover five bands (UMTS, PCS, DCS, GSM, and EGSM). 
     In the example of  FIG. 15 , antenna  54  also has a two-branch resonating element  54 - 1 . In the  FIG. 15  arrangement, slot  70  has been configured to cover the UMTS communications band. The first branch of antenna resonating element  54 - 1  (e.g., branch  98  of  FIG. 11 ) has been configured to cover both the DCS and PCS communications bands. The second branch of antenna resonating element  54 - 1  (e.g., branch  100  of  FIG. 11 ) has been configured to cover both the GSM and EGSM bands. As with the arrangement of  FIG. 14 , the antenna arrangement of  FIG. 15  may be considered to cover five bands (UMTS, PCS, DCS, GSM, and EGSM). 
     The table of  FIG. 16  corresponds to an illustrative configuration for antenna  54  in which antenna resonating element  54 - 1  has a three-branch resonating element such as antenna resonating element  54 - 1  of  FIG. 12 . As shown in  FIG. 16 , the first branch of antenna resonating element  54 - 1  (e.g., branch  99  of  FIG. 12 ) may be configured to cover the UMTS communications band. The second branch of antenna resonating element  54 - 1  (e.g., branch  101  of  FIG. 12 ) may be configured to cover the PCS communications band. Slot  70  may be configured to cover the DCS communications band. The GSM and EGSM communications bands may be covered by the third branch of antenna resonating element  54 - 1  (e.g., branch  103  of  FIG. 12 ). The antenna configuration of  FIG. 16  can be used to cover five communications bands (UMTS, PCS, DCS, GSM, and EGSM). 
     The table of  FIG. 17  corresponds to another illustrative configuration for antenna  54  in which antenna resonating element  54 - 1  has a three-branch resonating element such as antenna resonating element  54 - 1  of  FIG. 12 . As shown in the table of  FIG. 17 , the first branch of antenna resonating element  54 - 1  (e.g., branch  99  of  FIG. 12 ) may be configured to cover the UMTS communications band. Slot  70  may be configured to cover the PCS communications band. The second branch of antenna resonating element  54 - 1  (e.g., branch  101  of  FIG. 12 ) may be configured to cover the DCS communications band. The third branch of antenna resonating element  54 - 1  may be configured to cover both the GSM and EGSM communications bands (e.g., branch  103  of  FIG. 12 ). As with the three-branch antenna configuration of  FIG. 16 , the three-branch antenna configuration of  FIG. 17  can be used to cover five communications bands (UMTS, PCS, DCS, GSM, and EGSM). 
     In antenna arrangements of the type described in connection with  FIGS. 14 ,  15 ,  16 , and  17 , the highest communications band covered is UMTS (2170 MHz). In these designs, optional higher band antennas (e.g., for Bluetooth and WiFi at 2.4 GHz) may be provided in device  10 . For example, a 2.4 GHz antenna may be provided in the top portion of housing  12  in device  10  (i.e., at the opposite end of housing  12  from antenna  54 ). 
     Another suitable arrangement for covering additional communications bands such as the WiFi/Bluetooth band at 2.4 GHz is shown in the table of  FIG. 18 . With the arrangement of  FIG. 18 , six communications bands of interest are covered (WiFi, UMTS, PCS, DCS, GSM, and EGSM). Slot  70  may, as an example, be configured to cover the WiFi (and Bluetooth) communications band at 2.4 GHz. The first branch of antenna resonating element  54 - 1  (e.g., branch  99  of  FIG. 12 ) may be configured to cover the UMTS communications band. The second branch of antenna resonating element  54 - 1  (e.g., branch  101  of  FIG. 12 ) may be configured to cover both the DCS and PCS communications band. The third branch of antenna resonating element  54 - 1  (e.g., branch  103  of  FIG. 12 ) may be configured to cover both the GSM and EGSM communications bands. 
     As with the five band antenna arrangements described in connection with  FIGS. 14-17 , a six band antenna arrangement may be used in a handheld device that has one or more additional antennas for covering different communications bands. For example, another antenna resonating element (e.g., an antenna resonating element at the opposite end of housing  12 ) may be used to cover a 5 GHz band. Moreover, the GPS band at 1550 MHz can be covered (e.g., with an additional antenna in device  10  or by ensuring that one of the resonating element branches of resonating element  54 - 1  or slot  70  of hybrid PIFA-slot antenna  54  has an antenna resonance at 1550 MHz). 
     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: 20070828
Publication Date: 20110104
Grant Date: 20110104
Priority Date: 20070828
Inventors: HILL ROBERT J.
ZAVALA JUAN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/40", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/371", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/371", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/28", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/30", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 40406636