PATENT DOCUMENT

Publication Number: US-8599088-B2
Application Number: US-95919107-A
Country: US
Kind Code: B2

Title: Dual-band antenna with angled slot for portable electronic devices

Abstract:
Dual slot antennas are provided for portable electronic devices such as handheld electronic devices. A dual slot antenna may have an open slot that has an open end that is not encircled by conductive material and may have a closed slot in which each end is surrounded by conductor. The closed and open slots may have portions that run parallel to each other. The antenna may be fed using feed terminals that bridge the closed and open slots in the vicinity of the portions of the slots that run parallel to each other. The slots may have portions that are angled with respect to each other. An end portion of one of the slots may be bent and widened for impedance matching and broadened bandwidth. Other portions of the slots may also be angled with respect to their main longitudinal axes.

Claims:
What is claimed is: 
     
       1. A handheld electronic device comprising:
 transceiver circuitry; 
 a transmission line coupled to the transceiver circuitry; and 
 an antenna that is coupled to the transmission line, wherein the antenna has a ground plane that has dielectric-filled openings defining a first slot and a second slot, wherein the first slot has a main longitudinal axis, wherein the second slot has a main longitudinal axis, wherein the first and second slots are oriented so that the main longitudinal axis of the first slot is oriented at an angle of between 5° and 85° with respect to the main longitudinal axis of the second slot, wherein the ground plane is configured so that the second slot has a straight portion with a longitudinal axis that is oriented parallel to the main longitudinal axis of the first slot, wherein the second slot has a first width in the straight portion, wherein the ground plane is further configured to define an end portion of the second slot that has a longitudinal axis that is angled with respect to the longitudinal axis of the straight portion of the second slot and that has a second width that is larger than the first width in the straight portion, wherein the second width is perpendicular to the longitudinal axis of the end portion of the second slot, and wherein the end portion is substantially rectangular in shape and has a longitudinal axis that is oriented perpendicular to the longitudinal axis of the straight portion. 
 
     
     
       2. The handheld electronic device defined in  claim 1  wherein the antenna has first and second antenna feed terminals, the handheld electronic device further comprising:
 a dielectric support structure having first and second conductive vias that are coupled to first and second antenna feed terminals. 
 
     
     
       3. A dual slot handheld electronic device antenna formed from a ground plane, comprising:
 an open slot in the ground plane that has an open end; and 
 a closed slot in the ground plane that has a first portion that is oriented along a main longitudinal axis of the closed slot and that has a first width and that has first and second ends that are enclosed by conductive portions, wherein the second end of the closed slot has a longitudinal axis that is angled with respect to the main longitudinal axis of the closed slot and has a second width that is perpendicular to the longitudinal axis of the second end of the closed slot, wherein the second width is larger than the first width, wherein the first end of the closed slot has a longitudinal axis that is angled with respect to the main longitudinal axis of the closed slot and has a third width that is perpendicular to the longitudinal axis of the first end of the closed slot, and wherein the third width is approximately equal to the first width. 
 
     
     
       4. The dual slot handheld electronic device antenna defined in  claim 3  wherein the open slot has a length of at least 10 mm and operates at 2.4 GHz and wherein the closed slot has a length of at least 10 mm and operates at 5.4 GHz. 
     
     
       5. The dual slot handheld electronic device antenna defined in  claim 4  wherein the open slot has no angled portions and wherein the closed slot has at least one portion that is angled away from the open slot.

Description:
BACKGROUND 
     This invention relates to antennas, and more particularly, to antennas for portable electronic devices. 
     Due in part to their mobile nature, portable electronic devices are often provided with wireless communications capabilities. Portable electronic devices may use 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 (e.g., the main Global System for Mobile Communications or GSM cellular telephone bands). Portable electronic devices may also use other types of communications links. For example, portable electronic devices may communicate using the Wi-Fi® (IEEE 802.11) bands at 2.4 GHz and 5.4 GHz and the Bluetooth® band at 2.4 GHz. Communications are also possible in data service bands such as the 3 G data communications band at 2100 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 portable 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. These techniques can be used to produce antennas that fit within the tight confines of a compact portable device such as a handheld electronic device. With conventional portable electronic devices, however, design compromises are made to accommodate compact antennas. These design compromises may include, for example, compromises related to antenna efficiency and antenna bandwidth. 
     It would therefore be desirable to be able to provide improved antennas for portable electronic devices. 
     SUMMARY 
     Multiband slot antennas are provided for portable electronic devices such as handheld electronic devices. The multiband slot antennas may have a ground plane element with first and second openings that define respective first and second dielectric-filled slots. The first slot may be an open slot that has an air-filled end. The second slot may be a closed slot having ends that are surrounded by portions of the ground plane. 
     The open and closed slots may each have a main longitudinal axes. The main longitudinal axis of the closed slot may be angled with respect to the main longitudinal axis of the open slot. The slots may have additional angled portions and may have straight portions that run parallel to each other. The antenna may be fed using antenna terminals that bridge the first and second slots in the vicinity of the straight portions. 
     An end portion of one of the slots may be angled and widened with respect to the remainder of that slot for impedance matching and to enhance the bandwidth associated with that slot. 
     The first and second slots may be formed in part of a conductive portable electronic device housing. A dielectric support structure with conductive vias may be used to route signals from antenna feed terminals across the first and second slots. 
     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 portable electronic device such as a handheld electronic device in accordance with an embodiment of the present invention. 
         FIG. 2  is a schematic diagram of an illustrative portable electronic device in accordance with an embodiment of the present invention. 
         FIG. 3  is a diagram of an illustrative dual slot antenna in which one of the slots has an angled portion in accordance with an embodiment of the present invention. 
         FIG. 4  is a graph showing the performance of an illustrative dual slot antenna in which an end portion of the slot that handles the higher-frequency band is widened to enhance the bandwidth of the higher-frequency band in accordance with an embodiment of the present invention. 
         FIG. 5  is a diagram of an illustrative dual slot antenna with an alternative open slot configuration in accordance with an embodiment of the present invention. 
         FIG. 6  is a diagram of an illustrative dual slot antenna with an angled slot and a substantially straight slot having a relatively short angled portion in accordance with an embodiment of the present invention. 
         FIG. 7  is a diagram of an illustrative dual slot antenna having an angled slot with a relatively short angled portion at one of its ends in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of an illustrative dual slot antenna formed in a portable electronic device housing in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention relates generally to electronic devices, and more particularly, to antennas for wireless electronic devices. 
     The wireless electronic devices may be portable electronic devices such as laptop computers, tablet computers, wireless access point base stations such as IEEE 802.11 base stations, plug-in relay stations such as those for IEEE 802.11 communications, 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 may be handheld electronic devices. 
     Examples of portable and handheld electronic devices include cellular telephones, media players with wireless communications capabilities, handheld computers (also sometimes called personal digital assistants), remote controls, global positioning system (GPS) devices, and handheld gaming devices. The devices may also be hybrid devices that combine the functionality of multiple conventional devices. Examples of hybrid 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 portable electronic device such as a 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 handle communications over one or more 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. Typical data communications bands that may be handled by the wireless communications circuitry in device  10  include the 2.4 GHz band that is sometimes used for Wi-Fi® (IEEE 802.11) and Bluetooth® communications, the 5.4 GHz band that is sometimes used for Wi-Fi communications, the 1575 MHz Global Positioning System band, and 3 G data bands (e.g., the UMTS band at 1920-2170). These bands may be covered by using single and multiband antennas. For example, cellular telephone communications can be handled using a multiband cellular telephone antenna and local area network data communications can be handled using a multiband wireless local area network antenna. As another example, a device  10  may have a single multiband antenna for handling communications in two or more data bands (e.g., at 2.4 GHz and at 5.4 GHz). If desired, the antenna structures in device  10  may be used to implement multiple-in-multiple out (MIMO) schemes such as those used in supporting the IEEE 802.11n standard and in high-capacity cellular telephones, etc. 
     Device  10  may have housing  12 . Housing  12 , which is sometimes referred to as a case, may be formed of any suitable materials including plastic, glass, ceramics, metal, 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 operation of conductive antenna elements that are located in proximity to housing  12  is not disrupted by the housing. Housing  12  or portions of housing  12  may also be formed from conductive materials such as metal. An illustrative metal 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  and metal components in housing  12  may be shorted together to form a ground plane in device  10  or to expand a ground plane structure that is formed from a planar circuit structure as a printed circuit board structure (e.g., a printed circuit board structure used in forming antenna structures for device  10 ). 
     Device  10  may have one or more buttons such as buttons  14 . Buttons  14  may be formed on any suitable surface of device  10 . In the example of  FIG. 1 , buttons  14  have been formed on the top surface of device  10 . 
     If desired, device  10  may have a display such as display  16 . Display  16  may be a liquid crystal diode (LCD) display, an organic light emitting diode (OLED) display, a plasma 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. Buttons  14  may, if desired, be arranged adjacent to display  16 . With this type of arrangement, the buttons may be aligned with on-screen options that are presented on display  16 . A user may press a desired button to select a corresponding one of the displayed options. 
     Device  10  may have circuitry  18 . Circuitry  18  may include storage, processing circuitry, and input-output components. Wireless transceiver circuitry in circuitry  18  may be used to transmit and receive radio-frequency (RF) signals. Transmission lines such as coaxial transmission lines and microstrip transmission lines may be used to convey radio-frequency signals between transceiver circuitry and antenna structures in device  10 . As shown in  FIG. 1 , for example, transmission line  22  may be used to convey signals between antenna structure  20  and circuitry  18 . Transmission line  22  may be, for example, a coaxial cable that is connected between an RF transceiver (sometimes called a radio) and a multiband antenna. 
     A schematic diagram of an embodiment of an illustrative portable electronic device is shown in  FIG. 2 . Portable 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 or handheld electronic device. 
     As shown in  FIG. 2 , portable 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 Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, protocols for handling 3 G 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  and buttons  14  of  FIG. 1  are examples of input-output devices  38 . 
     Input-output devices  38  may include user input-output devices  40  such as buttons, touch screens, joysticks, click wheels, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, speakers, tone generators, vibrating elements, 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 (e.g., antenna structures such as antenna structures  20  of  FIG. 1 ), 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 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 3 G data communications band at 2100 MHz band (commonly referred to as UMTS or Universal Mobile Telecommunications System), Wi-Fi® (IEEE 802.11) bands (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 1575 MHz. Wi-Fi bands that may be supported include the 2.4 GHz band and the 5.0 GHz bands. The 5.0 GHz Wi-Fi bands extend from 5.15-5.85 GHz and are sometimes referred to by their approximate center frequency of 5.4 GHz (i.e., these communications frequencies are sometimes referred to as making up a 5.4 GHz communications 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 top view of illustrative antenna structures in accordance with an embodiment of the present invention is shown in  FIG. 3 . As shown in  FIG. 3 , antenna  20  may be formed from a ground plane structure such as ground plane  52 . Ground plane  52  may be formed from a printed circuit board, a planar metal structure, conductive electrical components, conductive housing walls, other suitable conductive structures, or combinations of these structures. With one suitable arrangement, ground plane  52  may be formed from one or more conductive layers on a printed circuit board. The printed circuit board may be rigid or flexible. An example of a rigid circuit board substrate is fiberglass-filled epoxy (e.g., FR4). An example of a flexible printed circuit board material is polyimide. Flexible printed circuits are sometimes referred to as flex circuits and may be mounted to dielectric support structures such as plastic supports. 
     Antenna resonating elements for antenna  20  may be formed from openings in ground plane  52 . In the example of  FIG. 3 , there are two openings in ground plane  52 : opening  54  and opening  56 . These openings are typically filled with air, but may, if desired, be filled with other suitable dielectrics such as plastic. Because openings such as openings  54  and  56  have lengths that are typically longer than their widths, openings of this type are often referred to as slots. 
     Slots  54  and  56  serve as antenna resonating elements for antenna  20 , whereas ground plane  52  serves as a ground plane element for antenna  20 . The slots and ground plane are sometimes referred to as forming “poles” for antenna  20 . For example, a first antenna structure may be formed by slot  54  (which serves as a first of two antenna poles for the first antenna structure) and ground plane  52  (which serves as a second of two antenna poles for the first antenna structure). Similarly, a second antenna structure can be formed from slot  56  (which serves as a first of two antenna poles for the second antenna structure) and ground plane  52  (which serves as a second of two antenna poles for the second antenna structure). Slots  54  and  56  may resonate at different frequencies, so that the antenna that is formed from slots  54  and  56  (and from ground plane  52 ) serves as a multiband antenna. The antenna structure formed from slot  54  and ground plane  52  may handle a first communications band, whereas the antenna structure formed from slot  56  and ground plane  52  may handle a second communications band. 
     Slots  54  and  56  may have any suitable shapes. For example, slot  54  may be completely surrounded by portions of ground plane element  52  (as with slot  56 ) or may have openings (as with opening  58  of slot  54 ). In a typical configuration, slots  54  and  56  are relatively long and thin. With this type of configuration, slots  54  and  56  have longitudinal dimensions that significantly exceed their lateral dimensions. 
     Any suitable feed arrangement may be used to feed antenna  20 . As shown schematically in the example of  FIG. 3 , a transmission line such as coaxial transmission line may be used to convey radio-frequency signals between antenna  20  and a radio-frequency transceiver such as radio-frequency transceiver  60 . Transceiver circuitry  60  may include one or more transceivers for handling communications in one or more discrete communications bands. For example, transceiver circuitry  60  may be used to handle communications in 2.4 GHz and 5.4 GHz communications bands. 
     Transmission line  22  may be coupled to antenna  20  at feed terminals such as feed terminals  62  and  64 . Feed terminal  64  may be referred to as a ground or negative feed terminal and may be shorted to the outer (ground) conductor of transmission line  22 . Feed terminal  62  may be referred to as the positive antenna terminal. Transmission line center conductor  68  may be used to connect transmission line  22  to positive feed terminal  62 . If desired, other types of antenna coupling arrangements may be used (e.g., based on near-field coupling, using impedance matching networks, etc.). 
     As shown schematically by dotted line  66  in  FIG. 3 , the feed arrangement for antenna  3  may include a matching network. Matching network  66  may include a balun (to match an unbalanced transmission line to a balanced antenna or to match a balanced transmission line to an unbalanced antenna) and/or an impedance transformer (to help match the impedance of the transmission line to the impedance of the antenna). 
     In the example of  FIG. 3 , slot  54  has a length L 1  and a width W 1 , whereas slot  56  has a length L 2  and a width W 2 . Slot widths W 1  and W 2  may be, for example, about 0.1 to 0.5 mm. The use of relatively small slot widths W 1  and W 2  may help reduce the length of the center conductor  68  (or comparable conductive structures used in matching network  66 ). If feed structures such as center conductor  68  are too large, their lengths may approach a quarter of a wavelength at the radio frequencies being handled by transceiver  60 . This could cause center conductor  68  to resonate, thereby reducing efficiency. Because relatively small slot widths W 1  and W 2  may allow use of a reduced feed width (i.e., a smaller lateral spacing between positive antenna feed terminal  62  and ground terminal  64 ), the use of small slot widths W 1  and W 2  may enhance antenna efficiency. 
     The length associated with open slot such as slot  54  may be substantially equal to a quarter of a wavelength at the slot&#39;s frequency of operation. For example, the length L 1  of open-ended slot  54  may be substantially equal to a quarter of a wavelength in a first communications band (i.e., at 2.4 GHz). The length of a close-ended slot such as closed slot  56  may be substantially equal to half of a wavelength at the slot&#39;s frequency of operation. For example, the length L 2  of close-ended slot  56  may be substantially equal to half of a wavelength in a second communications band (i.e., at 5.4 GHz). With this illustrative configuration, the lengths L 1  and L 2  may be, for example, about 10-20 mm (e.g., about 16 mm). 
     An advantage of arrangements of the type shown in  FIG. 3  in which an open-ended slot such as slot  54  is used to cover a lower frequency band while a close-ended slot such as slot  56  is used to cover a higher frequency band is that this prevents the slot that is associated with the lower frequency band from being much longer than the slot that is associated with the upper frequency band and allows the size of antenna  20  to be minimized. For example, the use of an open-ended geometry for slot  54  in the  FIG. 3  arrangement allows the length of slot  54  to be roughly equal to the length of slot  56 , even though slot  54  is used to cover a frequency band at roughly half of the frequency of the frequency band associated with slot  56 . 
     Slot  54  and/or slot  56  may contain portions that are not straight. In the illustrative arrangement of  FIG. 3 , for example, slot  56  has angled portion  70 . Angled portion  70  has a longitudinal axis (i.e., main longitudinal axis  72  of slot  56 ) that is oriented at an angle α with respect to main longitudinal axis  74  of slot  54 . Angle α may have a value of 10-45°, a value of 5-85°, or a value of 15-40° (as examples). The use of a non-zero angle α between slots  54  and  56  in antenna  20  helps to reduce near-field electromagnetic coupling between slots  54  and  56 . Such near-field coupling can create antenna losses, so the use of a non-zero angle to separate slots  54  and  56  can help to improve antenna efficiency. 
     As shown in  FIG. 3 , a slot in antenna  20  such as slot  56  may have a portion such as portion  76  that is angled (bent). Bent portion  76  may have an associated axis (longitudinal axis  78 ) that is oriented at a non-zero angle β with respect to axis  80 . Axis  80  is aligned with a central portion of slot  56  (i.e., a portion of slot  56  that lies between angled portion  70  and angled portion  76 ) and is aligned with main longitudinal axis  74  of slot  54 . In the example of  FIG. 3 , axis  78  and axis  80  are oriented at right angles with respect to each other (i.e., angle β is 90° in  FIG. 3 ). If desired, end portion  76  can be angled at other angles (e.g., angles β of between 70° and 110°). The use of a 90° angle in the  FIG. 3  arrangement is merely illustrative. 
     Because end portion  76  is angled, the footprint associated with slot  56  may be reduced in size. This may help ensure that slots  54  and  56  and ground plane element  52  can be accommodated within the potentially tight confines of housing  12 . Angled end portion  76  may also help to match the impedance of slot  56  to the impedance of the antenna feed (e.g., transmission line  22 ). 
     Portion  76  of slot  56  may have an associated length L 3  along longitudinal axis  78  and may have a width W 3 . The length L 3  of portion  76  is typically significantly smaller than overall slot length L 2 . With one illustrative arrangement, the width W 3  is greater than width W 2 . For example, in configurations in which width W 2  is about 0.1 to 0.5 mm, width W 3  may be 0.6 mm to several mm (as an example). 
     The larger width of angled portion  76  relative to the other portions of slot  56  may help to increase the bandwidth of slot  56 . This is illustrated in  FIG. 4 .  FIG. 4  is a graph in which the standing wave ratio (SWR) for an antenna such as antenna  20  of  FIG. 3  has been plotted as a function of frequency. As shown in  FIG. 4 , antenna  20  of  FIG. 3  covers a lower frequency band at 2.4 GHz and a higher frequency band at 5.4 GHz. Because of the presence of widened end portion  76  in slot  56 , the antenna bandwidth in the 5.4 GHz band (which is associated with slot  56 ) is larger than the antenna bandwidth in the 2.4 GHz band (which is associated with slot  54 ). This type of behavior may be helpful when the higher frequency band (e.g., the 5.4 GHz band in the  FIG. 4  example) requires a relatively larger bandwidth than the lower frequency band. 
     Slots  54  and  56  may be configured so that the second harmonic of the lower-frequency slot (slot  54 ) coincides with the higher-frequency band (directly or at a slight frequency offset). In this type of situation, the frequency response of the fundamental harmonic of slot  56  (e.g., at 5.4 GHz) may be widened due to both the presence of end portion  76  and the frequency response contribution of the second harmonic of lower-frequency slot  54 . If desired, the low frequency slot in antenna  20  (e.g., antenna slot  54 ) may be provided with a widened end portion in addition to or as an alternative to providing slot  56  with widened end portion  76 . 
     As shown in  FIG. 3 , widened end portion  76  may have a substantially rectangular shape. If desired, other shapes may be used for end portion  76  (e.g., portions with curved sides or other non-rectangular shapes). The use of a rectangular widened end portion  76  in the arrangement of  FIG. 3  is merely illustrative. 
       FIG. 5  shows an alternative layout that may be used for slot  54 . As shown in the arrangement of  FIG. 5 , slot  54  in antenna  20  may have an opening  58  that is not completely aligned with edge  82  of ground plane  52 . Nevertheless, arrangements of the type shown in  FIG. 5  may provide satisfactory antenna performance. In certain device configurations, omitting a corner of ground plane  52  as shown in  FIG. 5  may help ground plane  52  fit within housing  12  of device  10 . 
     Another possibly slot geometry is shown in  FIG. 6 . In the  FIG. 6  example, slot  54  has angled end portion  84 . Angled end portion  84  may be angled at any suitable angle with respect to longitudinal axis  74 . For example, angled end portion  84  may be oriented so that its longitudinal axis lies perpendicular to axis  74  as shown in  FIG. 6 . The width of slot portion  84  may be the same as the width of the other portions of slot  54  or may be different (e.g., wider or narrower). As with arrangements of the type shown in  FIG. 5 , the use of bent slot portion  84  in slot  54  may help antenna  20  accommodate design constraints such as constraints imposed by the geometry of device housing  12 . 
       FIG. 7  shows how slot  56  may have an angled portion such as angled portion  86 . Angled portion  86  and widened end portion  76  may be formed at opposite ends of slot  56 . Angled end portion  86  may be oriented at any suitable angle with respect to the other portions of slot  56 . For example, angled end portion  86  may be oriented so that its longitudinal axis is perpendicular to main longitudinal axis  72  of slot  56  as shown in  FIG. 7 . Portion  86  may have the same width as the central portion of slot  56  or may be wider or narrower than the central portion of slot  56 . The use of an angled portion such as angled portion  86  may help antenna  20  accommodate layout constraints (as an example). 
     Slot features such as uneven slot end  58  of slot  54  in  FIG. 5 , angled portion  84  of open slot  54  of  FIG. 6 , angled and widened slot portion  76  of slot  56  of  FIG. 3 , angled slot portion  70  of slot  56  of  FIG. 3 , and angled end portion  86  of closed slot  56  of  FIG. 7  may be used in any desired combination. The geometries of slots  54  and  56  that are shown in  FIGS. 3 ,  5 ,  6 , and  7  are merely illustrative. 
     If desired, antenna  20  may be integrated into a wall of housing  12  or may be otherwise mounted to an exterior portion of device  10 . This type of arrangement is shown in the cross-sectional view of  FIG. 8 . As shown in  FIG. 8 , housing  12  may have housing wall portions  12 A,  12 B, and  12 C that define slots such as slots  56  and  54 . Slots  54  and  56  may be filled with air or other suitable dielectric. Dielectric antenna feed structure  88  may be mounted to the interior of housing  12  in device  10 . Structure  88  may be formed from a layer of flex circuit or other suitable dielectric materials. Vias such as vias  90  and  92  may be used to provide conductive pathways through dielectric structure  88 . Vias  90  and  92  may be formed from metal or other suitable conductors. An example of a metal that may be used to form vias  90  and  92  is nickel. 
     Conductive pads such as pads  94  and  96  may be formed on the interior surface of dielectric support structure  88 . Pads  94  and  96  may be formed of metal or any other suitable conductive material. Similar pads may be formed on the opposing surface of dielectric support  88  to facilitate electrical contact between vias  90  and  92  and conductive housing wall portions  12 A and  12 C. 
     Pads  94  and  96  may serve as ground and positive antenna feed terminals for antenna  20 . In the schematic representation of  FIG. 8 , antenna terminals  62  and  64  are shown as being fed using a coaxial cable  22 . The coaxial cable may have an outer ground conductor that is electrically connected to ground antenna terminal  64  and may have a center conductor such as center conductor  68  that is electrically connected to positive antenna terminal  62 . This is, however, merely illustrative. Any suitable transmission line and/or matching network structures may be used to feed antenna terminals  62  and  64 . The arrangement of  FIG. 8  is presented as an example. 
     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: 20071218
Publication Date: 20131203
Grant Date: 20131203
Priority Date: 20071218
Inventors: CHIANG BING
SPRINGER GREGORY ALLEN
KOUGH DOUGLAS B.
AYALA ENRIQUE
MCDONALD MATTHEW IAN
XU HAO
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/371", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/371", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}]
Family ID: 39873988