PATENT DOCUMENT

Publication Number: US-10741909-B2
Application Number: US-201715716363-A
Country: US
Kind Code: B2

Title: Electronic devices having multi-band slot antennas

Abstract:
An electronic device may have peripheral conductive structures and a conductive layer that define edges of a slot element for a slot antenna. The slot element may be configured to cover wireless communications in a 1575 MHz satellite navigation band and 2.4 GHz and 5 GHz wireless local area network bands. A tuning circuit may be coupled across the slot approximately half way across the length of the slot. The antenna tuning circuit may include an inductor coupled in series with a notch filter (in scenarios where the slot is long enough to cover the 1575 MHz satellite navigation band in its fundamental mode) or may include a capacitor coupled in series with a notch or low pass filter. The fundamental mode and one or more harmonic modes of the slot element may cover the satellite navigation and wireless local area network bands.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 a conductive layer extending between the peripheral conductive structures, wherein the conductive layer and the peripheral conductive structures define edges of a slot element in a slot antenna, wherein the slot element has opposing first and second edges; 
 an antenna feed for the slot antenna that is coupled across the slot element between opposing third and fourth edges of the slot element at a first distance from the first edge; 
 radio-frequency transceiver circuitry coupled to the antenna feed and configured to convey radio-frequency signals in a first frequency band, a second frequency band that is greater than the first frequency band, and a third frequency band that is greater than the second frequency band using the slot element; and 
 an antenna tuning circuit for the slot antenna that tunes the antenna when the radio-frequency transceiver circuitry conveys radio-frequency signals with the antenna feed, wherein the antenna tuning circuit is coupled across the slot element between the opposing third and fourth edges of the slot element at a second distance from the first edge. 
 
     
     
       2. The electronic device defined in  claim 1 , wherein the antenna tuning circuit comprises an inductor and a filter coupled in series between the peripheral conductive structures and the conductive layer. 
     
     
       3. The electronic device defined in  claim 2 , wherein the filter comprises a notch filter. 
     
     
       4. The electronic device defined in  claim 3 , wherein the notch filter has a stop band that overlaps with the first frequency band and that does not overlap with the second and third frequency bands. 
     
     
       5. The electronic device defined in  claim 4 , wherein the slot element has a fundamental mode configured to cover the first frequency band and a second harmonic of the fundamental mode is configured to cover the second frequency band. 
     
     
       6. The electronic device defined in  claim 5 , wherein the slot element has a length extending between the opposing first and second edges of the slot element, the length is approximately equal to one half of a wavelength of operation of the slot element that is associated with the fundamental mode, and the antenna tuning circuit is coupled between the opposing third and fourth edges of the slot element at a location that is approximately half way between the first and second edges of the slot element. 
     
     
       7. The electronic device defined in  claim 6 , wherein the first frequency band comprises a satellite navigation frequency band at 1575 MHz, the second frequency band comprises a first wireless local area network frequency band between 2400 MHz and 2500 MHz, and the third frequency band comprises a second wireless local area network frequency band between 5150 MHz and 5850 MHz. 
     
     
       8. The electronic device defined in  claim 6 , wherein the first and third edges of the slot element are defined by the peripheral conductive structures and the second and fourth edges of the slot element are defined by the conductive layer. 
     
     
       9. The electronic device defined in  claim 8 , further comprising:
 a display, wherein the housing comprises a rear housing wall that opposes the display, the peripheral conductive structures comprise conductive sidewalls of the housing extending between the rear housing wall and the display, and the conductive layer comprises the rear housing wall. 
 
     
     
       10. The electronic device defined in  claim 1 , wherein the antenna tuning circuit comprises a capacitor and a filter coupled in series between the peripheral conductive structures and the conductive layer. 
     
     
       11. The electronic device defined in  claim 10 , wherein the filter is selected from the group consisting of: a notch filter having a stop band that overlaps with the second and third frequency bands and that does not overlap with the first frequency band and a low pass filter that is configured to pass signals in the first frequency band and to block signals in the second and third frequency bands. 
     
     
       12. The electronic device defined in  claim 11 , wherein the slot element has a fundamental mode configured to cover the first and second frequency bands and a first harmonic of the fundamental mode is configured to cover the third frequency band. 
     
     
       13. The electronic device defined in  claim 12 , wherein the slot element has a length extending between the opposing first and second edges of the slot element, the length is approximately equal to one half of a wavelength of operation of the slot element corresponding to a frequency in the second frequency band, and the antenna tuning circuit is coupled between opposing third and fourth edges of the slot element at a location that is approximately half way between the first and second edges of the slot element. 
     
     
       14. The electronic device defined in  claim 13 , further comprising:
 a dielectric structure within the slot element at the location that is approximately half way between the first and second edges of the slot element. 
 
     
     
       15. The electronic device defined in  claim 13 , wherein the transceiver circuitry comprises a first transceiver configured to handle the first frequency band and a second transceiver configured to handle the second and third frequency bands, the electronic device further comprising:
 a triplexer coupled between the first and second transceivers and the antenna feed. 
 
     
     
       16. The electronic device defined in  claim 1 , wherein the third edge has a length that is approximately equal to one-half of a wavelength of operation associated with a fundamental mode of the slot element, the fundamental mode of the slot element is configured to cover wireless communications in the first frequency band, and a harmonic mode of the slot element is configured to cover wireless communications in the second frequency band. 
     
     
       17. The electronic device defined in  claim 16 , wherein the antenna tuning circuit comprises:
 an antenna tuning component coupled between the third and fourth edges of the slot element at a location that is approximately halfway between the first and second edges of the slot element, wherein the antenna tuning component comprises an inductor coupled in series with a notch filter between the third and fourth edges of the slot element and the notch filter has a stop band that overlaps with the first frequency band. 
 
     
     
       18. The electronic device defined in  claim 16 , wherein the antenna tuning circuit comprises:
 an antenna tuning component coupled between the third and fourth edges of the slot element at a location that is approximately halfway between the first and second edges of the slot element, wherein the antenna tuning component comprises a capacitor coupled in series with a filter between the third and fourth edges of the slot element and the filter is configured to pass signals between the third and fourth edges in the first frequency band and to block signals from passing between the third and fourth edges in the second frequency band. 
 
     
     
       19. The electronic device defined in  claim 16 , further comprising:
 an additional antenna feed coupled across the slot element; 
 a first transceiver coupled to the antenna feed over a first radio-frequency transmission line and configured to generate radio-frequency signals in the first frequency band; 
 a second transceiver coupled to the additional antenna feed over a second radio-frequency transmission line and configured to generate radio-frequency signals in the second frequency band; 
 a notch filter interposed on the second radio-frequency transmission line, wherein the notch filter has a stop band that overlaps with the first frequency band; and 
 a low pass filter interposed on the first radio-frequency transmission line, wherein the low pass filter has a cutoff frequency between the first and second frequency bands. 
 
     
     
       20. The electronic device defined in  claim 1 , the electronic device further comprising:
 a filter circuit coupled between the third and fourth edges of the slot element, wherein the slot element is configured to convey radio-frequency signals in a 1575 MHz satellite navigation frequency band, a 2.4 GHz wireless local area network frequency band, and a 5 GHz wireless local area network frequency band. 
 
     
     
       21. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 a conductive layer extending between the peripheral conductive structures, wherein the conductive layer and the peripheral conductive structures define edges of a slot element in a slot antenna; 
 an antenna feed for the slot antenna that is coupled across the slot element at a first location; 
 radio-frequency transceiver circuitry coupled to the antenna feed and configured to convey radio-frequency signals in a first frequency band, a second frequency band that is greater than the first frequency band, and a third frequency band that is greater than the second frequency band using the slot element and the antenna feed; and 
 an antenna tuning circuit for the slot antenna that tunes the antenna when the radio-frequency transceiver circuitry conveys the radio-frequency signals in the first frequency band, wherein the antenna tuning circuit is coupled across the slot element parallel to the antenna feed at a second location that is different from the first location. 
 
     
     
       22. An electronic device, comprising:
 a housing having peripheral conductive structures; 
 a conductive layer extending between the peripheral conductive structures, wherein the conductive layer and the peripheral conductive structures define edges of a slot element in a slot antenna; 
 an antenna feed for the slot antenna that is coupled across the slot element; 
 radio-frequency transceiver circuitry coupled to the antenna feed and configured to convey radio-frequency signals in a first frequency band, a second frequency band that is greater than the first frequency band, and a third frequency band that is greater than the second frequency band using the slot element and the antenna feed; and 
 an antenna tuning circuit for the slot antenna that is coupled across the slot element, wherein the antenna tuning circuit includes a filter that forms an open circuit at one of the first, second, or third frequency bands.

Description:
BACKGROUND 
     This relates to electronic devices, and more particularly, to antennas for electronic devices with wireless communications circuitry. 
     Electronic devices such as portable computers and cellular telephones are often provided with wireless communications capabilities. To satisfy consumer demand for small form factor wireless devices, manufacturers are continually striving to implement wireless communications circuitry such as antenna components using compact structures. At the same time, there is a desire for wireless devices to cover a growing number of communications bands. 
     Because antennas have the potential to interfere with each other and with components in a wireless device, care must be taken when incorporating antennas into an electronic device. Moreover, care must be taken to ensure that the antennas and wireless circuitry in a device are able to exhibit satisfactory performance over a range of operating frequencies and with a satisfactory efficiency bandwidth. 
     It would therefore be desirable to be able to provide improved wireless communications circuitry for wireless electronic devices. 
     SUMMARY 
     An electronic device may have a housing with peripheral conductive structures and a conductive layer extending between the peripheral conductive structures. The conductive layer and the peripheral conductive structures may define edges of a slot element in a slot antenna. One or more antenna feeds for the slot antenna may be coupled across the slot element. 
     Radio-frequency transceiver circuitry may be coupled to the antenna feeds and may be configured to convey radio-frequency signals in a first frequency band (e.g., a 1575 MHz satellite navigation band), a second frequency band that is greater than the second frequency band (e.g., a 2.4 GHz wireless local area network band), and a third frequency band that is greater than the second frequency band (e.g., a 5 GHz wireless local area network band) using the slot element. An antenna tuning circuit for the slot antenna may be coupled across the slot element approximately half way across the length of the slot element. 
     In one suitable arrangement, the antenna tuning circuit may include an inductor coupled in series with a notch filter having a stop band that overlaps with the first frequency band and that does not overlap with the second and third frequency bands. The slot element may have a fundamental mode configured to cover the first frequency band and a second harmonic of the fundamental mode may be configured to cover the second frequency band. 
     In another suitable arrangement, the antenna tuning circuit may include a capacitor and a filter coupled in series between the peripheral conductive structures and the conductive layer. The filter may include a notch filter having a stop band that overlaps with the second and third frequency bands and that does not overlap with the first frequency band. If desired, the filter may include a low pass filter that is configured to pass signals in the first frequency band and to block signals in the second and third frequency bands. The fundamental mode of the slot element may be configured to cover the first and second frequency bands and a first harmonic of the fundamental mode may be configured to cover the third frequency band. In this way, the electronic device may use a single rectangular slot antenna to perform wireless communications over three or more frequency bands while maximizing device area for an active area of a display device, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device in accordance with an embodiment. 
         FIG. 2  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 3  is a diagram of illustrative wireless circuitry in an electronic device in accordance with an embodiment. 
         FIG. 4  is a diagram of illustrative slot antenna structures in accordance with an embodiment. 
         FIG. 5  is a top view of illustrative antenna structures in an electronic device in accordance with an embodiment. 
         FIG. 6  is a diagram of an illustrative slot antenna having a tuning capacitor and filter for covering multiple frequency bands in accordance with an embodiment. 
         FIG. 7  is a diagram showing how frequency responses of illustrative filter circuitry of the type shown in  FIG. 6  may be configured in accordance with an embodiment. 
         FIG. 8  is a graph of antenna performance (standing wave ratio) associated with use of illustrative antenna structures of the type shown in  FIG. 6  in accordance with an embodiment. 
         FIG. 9  is a diagram of an illustrative slot antenna having a tuning inductor and filter for covering multiple frequency bands in accordance with an embodiment. 
         FIG. 10  is a diagram showing how a frequency response of illustrative filter circuitry of the type shown in  FIG. 9  may be configured in accordance with an embodiment. 
         FIG. 11  is a graph of antenna performance (standing wave ratio) associated with use of illustrative antenna structures of the type shown in  FIG. 9  in accordance with an embodiment. 
         FIG. 12  is a diagram showing how illustrative antenna structures of the type shown in  FIGS. 6 and 9  may be fed using multiple antenna feeds in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG. 1  may be provided with wireless circuitry that includes antennas. The antennas may be used to transmit and receive wireless signals. 
     The wireless circuitry of device  10  may handle one or more communications bands. For example, the wireless circuitry of device  10  may include a Global Position System (GPS) receiver that handles GPS satellite navigation system signals at 1575 MHz or a GLONASS receiver that handles GLONASS signals at 1609 MHz. Device  10  may also contain wireless communications circuitry that operates in communications bands such as cellular telephone bands and wireless circuitry that operates in communications bands such as the 2.4 GHz Bluetooth® band and the 2.4 GHz and 5 GHz WiFi® wireless local area network bands (sometimes referred to as IEEE 802.11 bands or wireless local area network communications bands). Device  10  may also contain wireless communications circuitry for implementing near-field communications at 13.56 MHz or other near-field communications frequencies. If desired, device  10  may include wireless communications circuitry for communicating at 60 GHz, circuitry for supporting light-based wireless communications, or other wireless communications. 
     Electronic device  10  may be a computing device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wrist-watch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, equipment that implements the functionality of two or more of these devices, or other electronic equipment. In the illustrative configuration of  FIG. 1 , device  10  is a portable device such as a cellular telephone, media player, tablet computer, or other portable computing device. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     In the example of  FIG. 1 , device  10  includes a display such as display  14 . Display  14  may be mounted in a housing such as housing  12 . Device  10  may include a housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, parts of housing  12  may be formed from dielectric or other low-conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Display  14  may be mounted on the front face of device  10 . Display  14  may be a touch screen that incorporates capacitive touch electrodes or may be insensitive to touch. The rear face of housing  12  (i.e., the face of device  10  opposing the front face of device  10 ) may have a substantially planar rear housing wall such as wall  12 R. The rear housing wall may have slots that pass entirely through the rear housing wall and that therefore separate housing wall portions (and/or sidewall portions) of housing  12  from each other. The rear housing wall may include conductive portions and/or dielectric portions. If desired, the rear housing wall may include a planar metal layer covered by a thin layer or coating of dielectric such as glass, plastic, sapphire, or ceramic. Housing  12  may also have shallow grooves that do not pass entirely through housing  12 . The slots and grooves may be filled with plastic or other dielectric. If desired, portions of housing  12  that have been separated from each other (e.g., by a through slot) may be joined by internal conductive structures (e.g., sheet metal or other metal members that bridge the slot). 
     Housing  12  may include peripheral housing structures such as structures  12 W (sometimes referred to herein as peripheral structures  12 W). Structures  12 W may run around the periphery of device  10  and display  14 . In configurations in which device  10  and display  14  have a rectangular shape with four edges, structures  12 W may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding edges and that extend from rear housing wall  12 R to the front face of device  10  (as an example). Peripheral structures  12 W or part of peripheral structures  12 W may serve as a bezel for display  14  (e.g., a cosmetic trim that surrounds all four sides of display  14  and/or that helps hold display  14  to device  10 ) if desired. Peripheral structures  12 W may, if desired, form sidewall structures for device  10  (e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.). 
     Peripheral housing structures  12 W may be formed of a conductive material such as metal and may therefore sometimes be referred to as peripheral conductive housing structures, conductive housing structures, peripheral metal structures, peripheral conductive sidewalls, peripheral conductive housing sidewalls, peripheral conductive sidewall structures, sidewall structures, sidewalls, housing sidewalls, housing sidewall structures, or a peripheral conductive housing member (as examples). Peripheral housing structures  12 W may be formed from a metal such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming peripheral housing structures  12 W. 
     It is not necessary for peripheral housing structures  12 W to have a uniform cross-section. For example, the top portion of peripheral housing structures  12 W may, if desired, have an inwardly protruding lip that helps hold display  14  in place. The bottom portion of peripheral housing structures  12 W may also have an enlarged lip (e.g., in the plane of the rear surface of device  10 ). Peripheral housing structures  12 W may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when peripheral housing structures  12 W serve as a bezel for display  14 ), peripheral housing structures  12 W may run around the lip of housing  12  (i.e., peripheral housing structures  12 W may cover only the edge of housing  12  that surrounds display  14  and not the rest of the sidewalls of housing  12 ). 
     If desired, rear housing wall  12 R may be formed from a metal such as stainless steel or aluminum (rear housing wall  12 R may sometimes be referred to herein as conductive rear housing wall  12 R, rear wall  12 R, or conductive rear wall  12 R). Conductive rear housing wall  12 R may lie in a plane that is parallel to display  14 . In configurations for device  10  in which rear housing wall  12 R is formed from metal, it may be desirable to form parts of peripheral conductive housing structures  12 W as integral portions of the housing structures forming conductive rear housing wall  12 R of housing  12 . For example, conductive rear housing wall  12 R of device  10  may be formed from a planar metal structure and portions of peripheral housing structures  12 W on the sides of housing  12  may be formed as flat or curved vertically extending integral metal portions of the planar metal structure (e.g., conductive housing structures  12 R and  12 W may be formed from a continuous piece of metal in a unibody configuration). Housing structures such as these may, if desired, be machined from a block of metal and/or may include multiple metal pieces that are assembled together to form housing  12 . Conductive rear housing wall  12 R may have one or more, two or more, or three or more portions. Peripheral conductive housing structures  12 W and/or the conductive rear housing wall  12 R may form one or more exterior surfaces of device  10  (e.g., surfaces that are visible to a user of device  10 ) and/or may be implemented using internal structures that do not form exterior surfaces of device  10  (e.g., conductive housing structures that are not visible to a user of device  10  such as conductive structures that are covered with layers such as thin cosmetic layers, protective coatings, and/or other coating layers that may include dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of device  10  and/or serve to hide structures  12 W and/or  12 R from view of the user). 
     Display  14  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  14  may have an active area AA that includes an array of display pixels. The array of pixels may be formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma display pixels, an array of organic light-emitting diode display pixels or other light-emitting diode pixels, an array of electrowetting display pixels, or display pixels based on other display technologies. 
     Display  14  may be protected using a display cover layer such as a layer of transparent glass, clear plastic, transparent ceramic, sapphire, or other transparent crystalline material, or other transparent layer(s). The display cover layer may have a planar shape, a convex curved profile, a shape with planar and curved portions, a layout that includes a planar main area surrounded on one or more edges with a portion that is bent out of the plane of the planar main area, or other suitable shapes. The display cover layer may cover the entire front face of device  10 . In another suitable arrangement, the display cover layer may cover substantially all of the front face of device  10  or only a portion of the front face of device  10 . Openings may be formed in the display cover layer. For example, an opening may be formed in the display cover layer to accommodate a button such as button  16 . An opening may also be formed in the display cover layer to accommodate ports such as a speaker port. Openings may be formed in housing  12  to form communications ports (e.g., an audio jack port, a digital data port, etc.) and/or audio ports for audio components such as a speaker and/or a microphone if desired. 
     Display  14  may have an inactive border region that runs along one or more of the edges of active area AA. Inactive area IA may be free of pixels for displaying images and may overlap circuitry and other internal device structures in housing  12 . To block these structures from view by a user of device  10 , the underside of the display cover layer or other layer in display  14  that overlaps inactive area IA may be coated with an opaque masking layer in inactive area IA. The opaque masking layer may have any suitable color. 
     The antennas of the wireless circuitry in device  10  can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. 
     Gaps may be formed in the conductive structures that divide the conductive structures into segments. As an example, gaps may be formed between conductive structures such as portions of conductive rear housing wall  12 R, one or more peripheral conductive housing sidewalls  12 W, and/or other conductive structures in device  10 . The gaps may be used in forming one or more antennas for device  10 . 
     As an example, housing  12  may have four peripheral edges (e.g., peripheral conductive housing sidewalls  12 W) as shown in  FIG. 1  and one or more antennas may be located along one or more of these edges. As shown in the illustrative configuration of  FIG. 1 , antennas may, if desired, be mounted in regions  20  along opposing peripheral edges of housing  12  (as an example). The antennas may include antenna resonating elements that emit and receive wireless signals through the front of device  10  (i.e., through inactive portions IA of display  14 ) and/or from the rear and sides of device  10 . In practice, active components within active display area AA may block or otherwise inhibit signal reception and transmission by the antennas. By placing the antennas within regions  20  of inactive area IA of display  14 , the antennas may freely pass signals through the display without the signals being blocked by active display circuitry. Antennas may also be mounted in other portions of device  10 , if desired. The configuration of  FIG. 1  is merely illustrative. 
     In order to provide an end user of device  10  with as large of a display as possible (e.g., to maximize an area of the device used for displaying media, running applications, etc.), it may be desirable to increase the amount of area at the front face of device  10  that is covered by active area AA of display  14 . Increasing the size of active area AA may reduce the size of inactive area IA within device  10 . This may reduce the area of regions  20  that is available for forming antennas within device  10 . In general, antennas that are provided with larger operating volumes or spaces may have higher bandwidth efficiency than antennas that are provided with smaller operating volumes or spaces. If care is not taken, increasing the size of active area AA may reduce the operating space available to the antennas, which can undesirably inhibit the efficiency bandwidth of the antennas (e.g., such that the antennas no longer exhibit satisfactory radio-frequency performance). It would therefore be desirable to be able to provide antennas that occupy a small amount of space within device  10  (e.g., to allow for as large of a display active area AA as possible) while still allowing the antennas to operate with optimal efficiency bandwidth. 
     A schematic diagram showing illustrative components that may be used in device  10  of  FIG. 1  is shown in  FIG. 2 . As shown in  FIG. 2 , device  10  may include control circuitry such as storage and processing circuitry  28 . Storage and processing circuitry  28  may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in storage and processing circuitry  28  may be used to control the operation of device  10 . This processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, etc. 
     Storage and processing circuitry  28  may be used to run software on device  10 , such as internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, storage and processing circuitry  28  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  28  include internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols—sometimes referred to as WiFi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol, cellular telephone protocols, multiple-input and multiple-output (MIMO) protocols, antenna diversity protocols, etc. 
     Input-output circuitry  30  may include input-output devices  32 . Input-output devices  32  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  32  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  32  may include touch screens, displays without touch sensor capabilities, buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, position and orientation sensors (e.g., sensors such as accelerometers, gyroscopes, and compasses), capacitance sensors, proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors, etc.), fingerprint sensors (e.g., a fingerprint sensor integrated with a button such as button  24  of  FIG. 1  or a fingerprint sensor that takes the place of button  24 ), etc. 
     Input-output circuitry  30  may include wireless communications circuitry  34  for communicating wirelessly with external equipment. Wireless communications circuitry  34  may include radio-frequency (RF) transceiver circuitry formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas, transmission lines, and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). 
     Wireless communications circuitry  34  may include radio-frequency transceiver circuitry  90  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  36 ,  38 , and  42 . Transceiver circuitry  36  may handle wireless local area network (WLAN) bands such as 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and/or wireless personal area network (WPAN) bands such as the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  38  for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a low-midband from 960 to 1710 MHz, a midband from 1710 to 2170 MHz, a high band from 2300 to 2700 MHz, an ultra-high band from 3400 to 3700 MHz and/or other communications bands between 600 MHz and 4000 MHz or other suitable frequencies (as examples). 
     Circuitry  38  may handle voice data and non-voice data. Wireless communications circuitry  34  can include circuitry for other short-range and long-range wireless links if desired. For example, wireless communications circuitry  34  may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communications (NFC) circuitry, etc. Wireless communications circuitry  34  may include satellite navigation receive equipment such as global positioning system (GPS) receiver circuitry  42  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., Global Navigation Satellite System (GLONASS) signals, etc.). In WiFi® and Bluetooth® links and other short-range wireless links, wireless signals are typically used to convey data over tens or hundreds of feet. In cellular telephone links and other long-range links, wireless signals are typically used to convey data over thousands of feet or miles. 
     Wireless communications circuitry  34  may include antennas  40 . Antennas  40  may be formed using any suitable antenna types. For example, antennas  40  may include antennas with resonating elements that are formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, dipole antenna structures, monopole antenna structures, hybrids of these designs, etc. Different types of antennas may be used for different bands and combinations of bands. For example, one type of antenna may be used in forming a local wireless link antenna and another type of antenna may be used in forming a remote wireless link antenna. 
     As shown in  FIG. 3 , transceiver circuitry  90  in wireless circuitry  34  may be coupled to antenna structures  40  using paths such as path  92 . Wireless circuitry  34  may be coupled to control circuitry  28 . Control circuitry  28  may be coupled to input-output devices  32 . Input-output devices  32  may supply output from device  10  and may receive input from sources that are external to device  10 . 
     To provide antenna structures such as antenna(s)  40  with the ability to cover communications frequencies of interest, antenna(s)  40  may be provided with circuitry such as filter circuitry (e.g., one or more passive filters and/or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuitry. Capacitive structures, inductive structures, and resistive structures may also be formed from patterned metal structures (e.g., part of an antenna). If desired, antenna(s)  40  may be provided with tuning circuits such as tuning components  101  to tune antennas over communications bands of interest. Tuning components  101  may be part of a filter or impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and antenna ground, etc. 
     Tuning components  101  may include fixed components (e.g., inductors having a fixed inductance, resistors having a fixed resistance, capacitors having a fixed capacitance, etc.) and/or may include tunable (adjustable) components such as tunable inductors, tunable capacitors, or other tunable components. Fixed tuning components  101  may include discrete components such as surface mount technology (SMT) capacitors, resistors, and/or inductors and/or may include distributed components such distributed capacitances, resistances, and/or inductances. Adjustable tuning components  101  components may be based on switches and networks of fixed components, distributed metal structures that produce associated distributed capacitances and inductances, variable solid state devices for producing variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of device  10 , control circuitry  28  may issue control signals on one or more paths such as path  93  that adjust inductance values, capacitance values, or other parameters associated with adjustable components in tuning components  101 , thereby tuning antenna structures  40  to cover desired communications bands. Fixed components in tuning components  101  may, for example, configure antennas  40  to cover one or more desired frequency bands of interest with satisfactory antenna efficiency using the same conductive structures. 
     Path  92  may include one or more transmission lines. As an example, signal path  92  of  FIG. 3  may be a transmission line having a positive signal conductor such as line  94  and a ground signal conductor such as line  96 . Signal path  92  may sometimes be referred to herein as radio-frequency transmission line  92  or transmission line  92 . Transmission line  92  may include a stripline transmission line, a microstrip transmission line, waveguide transmission lines, or other transmission line structures. Transmission lines in device  10  such as transmission line  92  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, transmission lines in device  10  may also include transmission line conductors (e.g., signal and ground conductors) integrated within multilayer laminated structures (e.g., layers of a conductive material such as copper and a dielectric material such as a resin that are laminated together without intervening adhesive) that may be folded or bent in multiple dimensions (e.g., two or three dimensions) and that maintains a bent or folded shape after bending (e.g., the multilayer laminated structures may be folded into a particular three-dimensional shape to route around other device components and may be rigid enough to hold its shape after folding without being held in place by stiffeners or other structures). All of the multiple layers of the laminated structures may be batch laminated together (e.g., in a single pressing process) without adhesive (e.g., as opposed to performing multiple pressing processes to laminate multiple layers together with adhesive). 
     A matching network (e.g., an adjustable matching network formed using tuning components  101 ) may include components such as inductors, resistors, and capacitors used in matching the impedance of antenna(s)  40  to the impedance of transmission line  92 . Matching network components may be provided as discrete components (e.g., surface mount technology components) or may be formed from housing structures, printed circuit board structures, traces on plastic supports, etc. Components such as these may also be used in forming filter circuitry in antenna(s)  40  and may be tunable and/or fixed components. 
     Transmission line  92  may be coupled to antenna feed structures associated with antenna structures  40 . As an example, antenna structures  40  may form an inverted-F antenna, a slot antenna, a hybrid inverted-F slot antenna or other antenna having an antenna feed  95  with a positive antenna feed terminal such as terminal  98  and a ground antenna feed terminal such as ground antenna feed terminal  100 . Positive transmission line conductor  94  may be coupled to positive antenna feed terminal  98  and ground transmission line conductor  96  may be coupled to ground antenna feed terminal  100 . Other types of antenna feed arrangements may be used if desired. For example, antenna structures  40  may be fed using multiple feeds. The illustrative feeding configuration of  FIG. 3  is merely illustrative. 
     Control circuitry  28  may use information from a proximity sensor (see, e.g., sensors  32  of  FIG. 2 ), wireless performance metric data such as received signal strength information, device orientation information from an orientation sensor, device motion data from an accelerometer or other motion detecting sensor, information about a usage scenario of device  10 , information about whether audio is being played through speaker  26 , information from one or more antenna impedance sensors, and/or other information in determining when antenna(s)  40  is being affected by the presence of nearby external objects or is otherwise in need of tuning. In response, control circuitry  28  may adjust an adjustable inductor, adjustable capacitor, switch, or other tunable component  101  and/or may switch one or more antennas  40  into or out of use to ensure that wireless communications circuitry  34  operates as desired. 
     The presence or absence of external objects such as a user&#39;s hand may affect antenna loading and therefore antenna performance. Antenna loading may differ depending on the way in which device  10  is being held. For example, antenna loading and therefore antenna performance may be affected in one way when a user is holding device  10  in the user&#39;s right hand and may be affected in another way when a user is holding device  10  in the user&#39;s left hand. In addition, antenna loading and performance may be affected in one way when a user is holding device  10  to the user&#39;s head and in another way when the user is holding device  10  away from the user&#39;s head. To accommodate various loading scenarios, device  10  may use sensor data, antenna measurements, information about the usage scenario or operating state of device  10 , and/or other data from input-output circuitry  32  to monitor for the presence of antenna loading (e.g., the presence of a user&#39;s hand, the user&#39;s head, or another external object). Device  10  (e.g., control circuitry  28 ) may then adjust tunable components  101  in antenna  40  and/or may switch other antennas into or out of use to compensate for the loading (e.g., multiple antennas  40  may be operated using a diversity protocol to ensure that at least one antenna  40  may maintain satisfactory communications even while the other antennas are blocked by external objects). 
     Antennas  40  may include slot antenna structures, inverted-F antenna structures (e.g., planar and non-planar inverted-F antenna structures), loop antenna structures, combinations of these, or any other antenna structures. In one suitable arrangement, antenna  40  may be formed using a slot antenna structure. An illustrative slot antenna structure that may be used for forming antenna  40  is shown in  FIG. 4 . As shown in  FIG. 4 , slot antenna  40  may include a conductive structure such as structure  102  that has been provided with a dielectric opening such as dielectric opening  104 . Openings such as opening  104  of  FIG. 4  are sometimes referred to as slots, slot elements, slot resonating elements, or slot antenna resonating elements of slot antenna  40 . In the configuration of  FIG. 4 , opening  104  is a closed slot, because portions of conductive structure  102  completely surround and enclose opening  104 . Open slot antennas may also be formed in conductive materials such as conductive structure  102  (e.g., by forming an opening in the right-hand or left-hand end of conductive structure  102  so that opening  104  protrudes through conductive structure  102 ). 
     Antenna feed  95  for antenna  40  may be formed using positive antenna feed terminal  98  and ground antenna feed terminal  100 . In general, the frequency response of an antenna is related to the size and shapes of the conductive structures in the antenna. Slot antennas of the type shown in  FIG. 4  tend to exhibit response peaks when slot perimeter P is equal to the wavelength of operation of antenna  40  (e.g. where perimeter P is equal to two times length L plus two times width W). Such response peaks may, for example, be associated with electromagnetic standing waves on slot  104 . Antenna currents may flow between feed terminals  98  and  100  around perimeter P of slot  104 . As an example, where slot length L&gt;&gt;slot width W, the length L of antenna  40  will tend to be about half of the length of other types of antennas such as inverted-F antennas configured to handle signals at the same frequency. Given equal antenna volumes, slot antenna  40  will therefore be able to handle signals at approximately twice the frequency of other antennas such as inverted-F antennas, for example. 
     Feed  95  may be coupled across slot  104  at a location along length L. For example, feed  95  may be located at a distance  105  from one side of slot  104 . Distance  105  may be adjusted to match the impedance of antenna  40  to the impedance of the corresponding transmission line (e.g., transmission line  92  of  FIG. 3 ). For example, the antenna current flowing around slot  104  may experience an impedance of zero at the left and right edges of slot  104  (e.g., a short circuit impedance) and an infinite (open circuit) impedance at the center of slot  104  (e.g., at a fundamental frequency of the slot). Distance  105  from edge  130  may be located between the center of slot  104  and the left edge at a location where the antenna current experiences an impedance that matches the impedance of the corresponding transmission line, for example (e.g., distance  105  may be between 0 and ¼ of the wavelength of operation of antenna  40 ). 
     The example of  FIG. 4  is merely illustrative. In general, slot  104  may have any desired shape (e.g., where the perimeter P of slot  104  defines resonant characteristics of antenna  40 ). For example, slot  104  may have a meandering shape with different segments extending in different directions, may have straight and/or curved edges, etc. Conductive structure  102  may be formed from any desired conductive electronic device structures. For example, conductive structure  102  may include conductive traces on printed circuit boards or other substrates, sheet metal, metal foil, conductive structures associated with a display (e.g., display  14  of  FIG. 1 ), conductive portions of the electronic device housing (e.g., conductive walls  12 W and/or  12 R of  FIG. 1 ), or other conductive structures within device  10 . In one suitable arrangement, different sides (edges) of slot  104  may be defined by different conductive structures. 
     A top interior view of an illustrative device  10  that contains antennas is shown in  FIG. 5 . As shown in  FIG. 5 , device  10  may have peripheral conductive housing structures such as peripheral conductive housing sidewalls  12 W (e.g., four peripheral conductive housing sidewalls  12 W each extending along a respective side of device  10 ). Peripheral conductive housing sidewalls  12 W may be continuous or may be divided by dielectric-filled peripheral gaps (e.g., plastic gaps). A conductive structure such as conductive layer  120  may extend between peripheral conductive housing sidewalls  12 W. Conductive layer  120  may be formed from conductive housing structures, conductive structures from electrical device components in device  10 , printed circuit board traces, strips of conductor such as strips of wire and metal foil, conductive components in display  14 , and/or other conductive structures. In one suitable arrangement, conductive layer  120  is formed from the conductive rear wall of housing  12  (e.g., conductive rear housing wall  12 R as shown in  FIG. 1 ). 
     As shown in  FIG. 5 , conductive layer  120  (e.g., conductive rear housing wall  12 R) may extend between the opposing left and right edges and the opposing top and bottom edges (sidewalls) of device  10 . One or more slot antennas  40  may be formed from conductive layer  120  and/or peripheral conductive housing sidewalls  12 W (e.g., within regions  20  at the upper and lower ends of device  10  under inactive area IA of display  14 , as shown in  FIG. 1 ). The slot elements  104  in each slot antenna  40  may have edges defined by conductive layer  120  and one or more peripheral conductive housing sidewalls  12 W. For example, a first slot antenna  40 - 1  may be formed at the upper-left corner of device  10 , a second slot antenna  40 - 2  may be formed at the upper-right corner of device  10 , a third slot antenna  40 - 3  may be formed at the lower-left corner of device  10 , and a fourth slot antenna  40 - 4  may be formed at the lower-right corner of device  10 . Each slot antenna  40  may have a corresponding feed  95  coupled across the corresponding slot element  104  (e.g., antenna  40 - 1  may have a slot element  104 - 1  fed by feed  95 - 1 , antenna  40 - 2  may have a slot element  104 - 2  fed by feed  95 - 2 , etc.). 
     Antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and/or  40 - 4  may be used to cover the same frequency band or may be used to cover two or more different frequency bands. In scenarios where antennas  40  cover the same band, two or more antennas  40  may be operated using a MIMO scheme to optimize data throughput if desired. If desired, two or more antennas  40  may be operated using an antenna diversity scheme. For example, in scenarios where antennas  40 - 1  and  40 - 2  are being blocked by an external object, antennas  40 - 3  and/or  40 - 4  may be switched into use, in scenarios where antenna  40 - 3  is blocked one or more of antennas  40 - 1 ,  40 - 2 , and  40 - 3  may be switched into use, etc. 
     Slots  104  of antennas  40  may be filled with any desired dielectric material (e.g., air, plastic, ceramic, glass, sapphire, combinations of these, etc.). In the example where conductive layer  120  is formed from conductive rear housing wall  12 R of device  10 , dielectric material in slots  104  may form part of the exterior surface of device  10  and may lie flush with conductive rear housing wall  12 R and/or portions of peripheral conductive housing sidewalls  12 W, if desired. 
     The example of  FIG. 5  is merely illustrative. If desired, one, two, three, four, or more than four antennas  40  may be formed within device  10  (e.g., using corresponding slots  104  and feeds  95 ). Each of slots  104  may have two edges defined by two different peripheral conductive housing sidewalls  12 W or, if desired, one or more of slots  104  may have three edges defined by conductive layer  120  and one edge defined by a corresponding peripheral conductive housing sidewall  12 W. Antennas  40  may each include slots  104  having the same shape and dimensions or two or more antennas  40  may have slots with different shapes or dimensions. Slots  104  may be rectangular in shape or may have other shapes (e.g., shapes having meandering segments, curved segments, straight segments, etc.). Slots  104  may have curved and/or straight edges. One or more slots  104  may have other orientations. If desired, one or more slots  104  may be completely surrounded by conductive layer  120  (e.g., each of the edges of the slot  104  may be defined by conductive layer  120 ). One or two of the edges of one or more slots  104  may be defined by a curved portion of housing  12  where peripheral conductive housing sidewalls  12 W join with conductive layer  120  (e.g., in scenarios where peripheral conductive housing sidewalls  12 W and rear housing wall  12 R are formed from a single continuous piece of metal in a unibody configuration). The example of  FIG. 5  in which the positive feed terminal of each feed  95  is coupled to a corresponding peripheral conductive housing sidewall  12 W and the ground feed terminal of each feed  95  is coupled to conductive layer  120  is merely illustrative. If desired, one or more antennas  40  may have a positive feed terminal coupled to layer  120  and a ground feed terminal coupled to a corresponding peripheral conductive housing sidewall  12 W. Device  10  need not have a substantially rectangular periphery and may, if desired, have other shapes. 
     In practice, the length and perimeter of slot  104  (e.g., length L and perimeter P as shown in  FIG. 4 ) may determine the operating frequencies of a given one of slot antennas  40 . However, in practice, it may be desirable for device  10  to be able to cover multiple frequency bands. In some scenarios, separate antennas may be formed to cover additional frequency bands. However, this may consume an excessive amount of valuable space within device  10 . If desired, slot antenna  40  may be configured to cover multiple frequency bands, thereby eliminating the need for separate antennas for covering multiple frequency bands. In one suitable arrangement, slot antenna  40  may be configured to concurrently cover three different bands such as a satellite navigation band (e.g., a GPS band centered at 1575 MHz), a wireless local area network (or Bluetooth) band at 2.4 GHz, and a wireless local area network band at 5 GHz. 
       FIG. 6  is a diagram showing how a given slot antenna  40  (e.g., a given one of slot antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  of  FIG. 5 ) may be configured to cover three different frequency bands such as a satellite navigation band and 2.4 GHz and 5 GHz wireless local area network bands using a single rectangular slot  104 . 
     As shown in  FIG. 6 , slot antenna  40  may include a slot element  104  between different portions of conductive structures  102 . If desired, one or more edges of slot element  104  may be defined by a conductive layer (e.g., conductive layer  120  of  FIG. 5 ) and the remaining edges of slot element  104  may be defined by one or more conductive sidewalls (e.g., peripheral conductive housing sidewalls  12 W as shown in  FIG. 5 ). In an example where antenna  40  of  FIG. 6  is used to form antenna  40 - 1  of  FIG. 5 , edges  134  and  130  of slot  104  may be defined by the left and upper peripheral conductive housing sidewalls  12 W of housing  12  whereas edges  136  and  132  of slot  104  are defined by conductive layer  120  (e.g., conductive rear housing wall  12 R). 
     Antenna  40  may be fed using feed  95  coupled across length L of slot  104 . For example, positive feed terminal  98  may be coupled to edge  134  of conductive structures  102  (e.g., an edge defined by one of peripheral conductive housing sidewalls  12 W) and ground feed terminal  100  may be coupled to edge  136  of conductive structures  102  (e.g., an edge defined by conductive layer  120 ). Antenna feed  95  may be located at distance  138  from edge  130  of slot  104 . Distance  138  may be selected to ensure that feed  95  is impedance matched with transmission line  92 . Distance  138  may, for example, be 9 mm, between 5 mm and 10 mm, between 2 mm and 12 mm, or any other suitable distance. 
     Slot  104  may have a width W perpendicular to length L. In order to ensure that antenna  40  is not blocked by conductive circuitry in display  14 , width W may, for example, be limited by the size of inactive area IA of display  14  ( FIG. 1 ). As examples, width W may be approximately 0.9 mm, between 0.5 mm and 1.5 mm, between 0.7 mm and 1.2 mm, etc. Decreasing the size of inactive area IA (and thus width W) may maximize the size of active area AA on display  14  for a user of device  10 , for example. 
     Positive signal conductor  96  of transmission line  92  may be coupled to positive feed terminal  98  whereas ground signal conductor  94  of transmission line  92  may be coupled to ground feed terminal  100 . In order to allow the same feed  95  to handle signals in three different frequency bands, transmission line  92  may extend between feed  95  and filter circuitry such as filter  142 . Filter  142  may have a first port coupled to transmission line  92 , a second port coupled to wireless local area network transceiver  36 , and a third port coupled to satellite navigation receiver  42 . Filter  142  may isolate the signals conveyed by wireless local area network transceiver circuitry  36  from the signals conveyed by satellite navigation receiver  42 . For example, filter  142  may receive radio-frequency signals in both 2.4 GHz and 5 GHz wireless local area network bands from transceiver circuitry  36  (e.g., over different ports of transceiver  36 ) and may combine the signals before conveying the combined signals to feed  95 . Similarly, filter  142  may receive radio-frequency signals from feed  95  and may filter the signals by frequency so that the signals in the 2.4 GHz band (e.g., at frequencies between 2400 MHz and 2500 MHz) and the signals in the 5 GHz band (e.g., at frequencies between 5150 MHz and 5850 MHz) are conveyed to corresponding ports of transceiver  36  while the signals in the satellite navigation band (e.g., at 1575 MHz) are conveyed to receiver  42 . Filter  142  may, for example, include a triplexer circuit or any other desired filtering circuitry. The triplexer may, for example, include one or more low-pass filters, band-pass filters, band stop filters, and/or high pass filters. In this way, feed  95  may support communications over both 2.4 GHz and 5 GHz WLAN bands and a satellite navigation band. Other arrangements may be used if desired. 
     The length L of slot  104  (e.g., the length of parallel edges  134  and  136 ) may be selected so that antenna  40  handles radio-frequency signals in a desired frequency band. For example, length L may be approximately equal to one-half of a wavelength corresponding to the desired frequency band. 
     Slot  104  may be characterized by multiple electromagnetic standing wave modes that are associated with different response peaks for antenna  40 . These discrete modes may be determined by the dimensions of slot  104  (e.g., length L). For example, the dimensions of slot  104  may define the boundary conditions for electromagnetic standing waves in each of the standing wave modes that are excited on slot  104  by antenna currents conveyed over feed  95  and/or by received radio-frequency signals. Such standing wave modes of slot  104  include a fundamental mode and one or more harmonics of the fundamental mode (i.e., so-called harmonic modes of slot  104 ). Slot  104  may exhibit antenna performance peaks at frequencies associated with the fundamental mode and one or more of the harmonic modes of slot  104  (e.g., where the harmonic modes are typically at integer multiples of the fundamental modes). 
     Curves  151 ,  153 , and  155  are shown on  FIG. 6  to illustrate some of the standing wave modes of slot  104 . As shown in  FIG. 6 , curves  151 ,  153 , and  155  plot the voltage across slot  104  (perpendicular to length L) at different points along length L. Similarly, curves  151 ,  153 , and  155  may also represent the magnitude of the electric field E0 within slot  104  at different points along length L (e.g., where field E0 extends in a direction parallel to width W). In each mode, nodes in the voltage distribution are present at edges  130  and  132  (e.g., length L establishes boundary conditions for the electromagnetic standing waves produced on slot  104  in the different modes). 
     Curve  151  represents the voltage distribution across slot  104  in the fundamental mode. As shown in  FIG. 6 , in fundamental mode  151 , the voltage across slot  104  (e.g., in a direction parallel to edges  130  and  132 ) and the magnitude of electric field E0 reaches a maximum (e.g., an anti-node) at distance  140  from edge  130  of slot  104  (e.g., half way across length L). Dimension L may establish the fundamental mode, where dimension L is approximately one half of the corresponding wavelength of operation. The wavelength of operation may, for example, be an effective wavelength of operation based on the dielectric material within slot  104 . 
     Curve  153  represents the voltage distribution across slot  104  in a first harmonic mode. As shown in  FIG. 6 , in first harmonic mode  153 , the voltage across slot  104  and the magnitude of electric field E0 reach maxima (anti-nodes) at one-quarter and three-quarters of distance L from edge  130 . At the same time, in the first harmonic mode the voltage across slot  104  and the magnitude of electric field E0 are at a node (e.g., a minimum or zero-value) at distance  140  from edge  130  of slot  104  (e.g., half way across length L). Antenna  40  may exhibit a response peak associated with the first harmonic mode at a frequency that is approximately twice the frequency associated with fundamental mode  151 , for example. 
     Curve  155  represents the voltage distribution across slot  104  in a second harmonic mode. As shown in  FIG. 6 , in second harmonic mode  155 , the voltage across slot  104  and the magnitude of electric field E0 reach maxima (anti-nodes) at one-sixth, one-half, and five sixths of distance L from edge  130 . At the same time, the voltage across slot  104  and the magnitude of electric field E0 form nodes at one-third and two-thirds of distance L from edge  130 . Antenna  40  may exhibit a response peak associated with the second harmonic mode at a frequency that is approximately three times the frequency associated with fundamental mode  151 , for example. While the example of  FIG. 6  only shows three standing wave modes, higher order harmonics may be present on slot  104  in practice. 
     Modes  151 ,  153 , and/or  155  may support coverage in corresponding frequency bands for antenna  40 . In one suitable arrangement, it may be desirable to cover a satellite navigation frequency band at 1575 MHz, a 2.4 GHz WLAN frequency band, and a 5 GHz WLAN frequency band using two or more of modes  151 ,  153 , and  155 . However, because frequencies in the 2.4 GHz band are not a perfect integer multiple of frequencies in the 1575 MHz band and frequencies in the 5 GHz band are not perfect integer multiples of frequencies in the 1575 and 2.4 GHz bands, the dimensions of slot  104  in themselves may be insufficient for covering all three of these frequency bands. If desired, antenna components may be coupled across slot  104  that configure antenna  40  to cover these frequency bands using two or more of modes  151 ,  153 , and  155 . 
     If desired, dielectric structures such as dielectric structure  150  may be formed at one or more locations within slot  104 . Dielectric structure  150  may, for example, have a higher dielectric constant than the other dielectric material that fills slot  104 . Dielectric structure  150  may dielectrically load slot  104  to increase effective electrical length of slot  104  at one or more frequencies covered by slot  104 . Increasing the effective electrical length may serve to shift the corresponding frequencies covered by slot  104  to lower frequencies. Dielectric structure  150  may be placed within slot  104  at a selected location such that dielectric structure  150  loads slot  104  at some frequencies but not at others (e.g., so that the effective electrical length and the corresponding operating frequency of slot  104  is shifted lower for some frequencies but not for others). 
     In practice, dielectric structure  150  may load slot  104  in a particular frequency band when dielectric structure  150  is located at an anti-node of the standing wave mode for that band. For example, dielectric structure  150  may be placed within slot  104  at distance  140  from edge  130 . At this location, dielectric structure  150  may dielectrically load slot  104  at frequencies that are covered by fundamental mode  151  and second harmonic mode  155 , which exhibit antinodes and thus relatively strong electric fields at distance  140  from edge  130  (e.g., relatively strong electric fields may interact more strongly with tuning components and/or dielectrics than relatively weak electric fields). Dielectric structure  150  may thereby serve to increase the effective electrical length of slot  104  at the frequencies associated with modes  151  and  155  when structure  150  is placed at distance  140  from edge  130  (thereby shifting the corresponding frequencies associated with modes  151  and  155  to lower frequencies). However, dielectric structure  150  may not have any frequency impact on mode  153 , which has a node (e.g., zero electric field magnitude) at distance  140  from edge  130 . Distance  140  from edge  130  may sometimes be referred to herein as location  140 . 
     In order to support satisfactory standing wave ratio and antenna efficiency at frequencies in each of the three frequency bands to be handled by antenna  40 , a tuning circuit such as tuning component  156  may be coupled between edges  134  and  136  of slot  104  (e.g., a tuning circuit that includes as tuning components  101  of  FIG. 3 ). Tuning component  156  may be coupled across slot  104  at a distance  140  from edge  130  of slot  104 . Distance  140  may, for example, be approximately equal to one-half of length L (e.g., within 15% of one-half of length L). 
     The placement of tuning component  156  may be selected so that tuning component  156  impacts the performance of antenna  40  at some frequencies but not at others. In practice, tuning component  156  may affect the performance of antenna  40  in a particular frequency band when the tuning component is located at an anti-node of the standing wave mode for that band. For example, at distance  140  from edge  130 , tuning component  156  may be capable of impacting the frequency response of antenna  40  at frequencies that are covered by fundamental mode  151  and second harmonic mode  155 , which have antinodes and thus relatively strong electric fields at distance  140  from edge  130 . However, tuning component  156  may not have any frequency impact on mode  153 , which has a node at distance  140  from edge  130 . 
     Tuning component  156  may include a capacitive circuit such as capacitor  154  coupled in series with a filter circuit such as filter  152  between edges  134  and  136  of slot  104 . Filter  152  may, for example, be a notch filter or a low pass filter that forms a short circuit at satellite navigation frequencies such as 1575 MHz and that forms an open circuit at higher frequencies such as frequencies in the 2.4 GHz and 5 GHz wireless local area network bands. 
     When filter  152  forms an open circuit (e.g., at WLAN frequencies), capacitor  154  is floating and does not impact the frequency response of antenna  40 . However, when filter  152  forms a short circuit path (e.g., at GPS frequencies), capacitor  154  may be coupled to edge  136  and may serve to increase the effective electrical length of slot  104 . Because filter  152  may be configured to form a short circuit at frequencies associated with fundamental mode  151  and an open circuit at frequencies associated with harmonic mode  155 , capacitor  154  may increase the effective electrical length of slot  104  to shift corresponding frequencies associated with fundamental mode  151  lower without affecting the frequency response associated with harmonic mode  155 . Because capacitor  154  is located at a node of harmonic mode  153 , capacitor  154  may not affect the frequency response associated with mode  153  regardless of whether filter  152  forms an open or closed circuit. When configured in this way, the frequency response of slot  104  may cover frequencies in all three of the 1575 MHz GPS band, the 2.4 GHz WLAN band, and the 5 GHz WLAN band with satisfactory efficiency. 
     Some possible transmissions T that may be exhibited by filter of  FIG. 6  as a function of frequency are shown in  FIG. 7 . In the graph of  FIG. 7 , the transmission of filter  152  when formed using a low pass filter is represented by the transmission characteristic of line  160 , whereas the transmission of filter  152  when formed using a notch filter is represented by the transmission characteristic of line  162 . 
     As indicated by line  160 , when configured as a low pass filter, filter  152  may block signals with frequencies greater than frequency F 1 ′ and may pass signals with frequencies less than cutoff frequency F 1 ′ such as frequency F 1 . Frequency F 1  may, for example, be a frequency within the 1575 MHz GPS band handled by antenna  40 . At frequencies less than cutoff frequency F 1 ′, capacitor  154  may be electrically connected in series between edges  134  and  136  of slot  104 . At frequencies greater than cutoff frequency F 1 ′ such as frequencies F 2  and F 3 , an open circuit may be formed between edges  134  and  136  at the location of component  156 . Frequency F 2  may, for example, correspond to a frequency within the 2.4 GHz WLAN band (e.g., between 2400 MHz and 2500 MHz) whereas frequency F 3  may correspond to a frequency within the 5 GHz WLAN band (e.g., between 5150 MHz and 5850 MHz). In this way, capacitor  154  may be invisible to signals at WLAN frequencies and may affect the radiating characteristics of antenna  40  at GPS frequencies. 
     As indicated by line  162 , when configured as a notch filter, filter  152  may pass signals at frequencies outside of a stop band between cutoff frequencies FL and FH and may block signals at frequencies within the stop band between cutoff frequencies FL and FH. The notch filter may be configured so that the stop band of the filter overlaps with both frequencies F 2  and F 3  (e.g., so that the stop band overlaps the 2.4 GHz and 5 GHz WLAN bands). When configured as a notch filter, at frequencies greater than frequency FL and less than frequency FH, an open circuit may be formed between edges  134  and  136  at the location of component  156  (e.g., capacitor  154  may be invisible to signals in the 2.4 GHz and 5 GHz WLAN bands). At frequencies outside of the stop band such as GPS frequencies at frequency F 1 , capacitor  154  may be coupled between sides  134  and  136  of slot  104  and may affect the radiating characteristics of antenna  40  at GPS frequencies. Frequency FL may be, for example, 2400 MHz, 2300 MHz, 2200 MHz, 2000 MHz, or any other desired frequency between frequencies F 1  and F 2 . Frequency FH may be, for example, 5850 MHz, 5500 MHz, or any other desired frequency greater than frequency F 3 . The examples of  FIG. 7  are merely illustrative and, in general, any desired filter structures may be used. 
       FIG. 8  is a graph in which antenna performance (standing wave ratio) has been plotted as a function of frequency for antenna  40  having tuning circuit  156  coupled across slot  104 . Three performance curves are shown in  FIG. 8 . The length L of slot  104  may be selected to be approximately equal to one half of the wavelength corresponding to frequency F 2 ′. As an example, frequency F 2 ′ may be approximately 2.7 GHz. The fundamental mode of slot  104  may therefore support communications in a frequency band around F 2 ′ (e.g., around 2.7 GHz). The first harmonic mode of slot  104  may be present at frequency F 3 , which is approximately two times frequency F 2 ′ (e.g., around 5.4 GHz). Response curve  174  may exhibit a bandwidth that extends across the 5 GHz WLAN frequency band (e.g., from 51510 MHz to 5850 MHz). This harmonic mode of slot  104 , as represented by response curve  174 , may allow antenna  40  to support communications at any desired frequencies within the 5 GHz WLAN frequency band (e.g., at frequency F 3  or other frequencies from 5150 MHz to 5850 MHz). 
     The first harmonic mode of the 2.4 GHz WLAN band may include frequencies that are too low to sufficiently cover the 5 GHz WLAN band (i.e., the first harmonic mode of the 2.4 GHz band may be approximately two times 2.4 GHz or 4.8 GHz). Therefore, selecting length L to allow the fundamental mode of slot  104  to cover a frequency band around 2.7 GHz may push the first harmonic mode into frequencies within the 5 GHz WLAN band. 
     In order to recover a response in the 2.4 GHz WLAN band, dielectric structure  150  may be formed at distance  140  from edge  130  within slot  104  ( FIG. 6 ). The presence of dielectric structure  150  at distance  140  from edge  130  may dielectrically load slot  104  at the fundamental mode (e.g., at frequencies around 2.7 GHz) to increase the effective electrical length of slot  104 . This may serve to push the fundamental frequency to a lower frequency such as frequency F 2 , as shown by arrow  175  and response curve  172 . Frequency F 2  may, for example, be 2.4 GHz. Response curve  172  may exhibit a bandwidth that extends across the 2.4 GHz WLAN frequency band (e.g., from 2400 MHz to 2500 MHz). The presence of dielectric structure  150  may not dielectrically load slot  104  at the first harmonic of slot  104  (e.g., at frequencies in the 5 GHz WLAN band as shown by curve  174 ), because distance  140  from edge  130  is at a node of the first harmonic mode, as shown by curve  153  of  FIG. 6 . Dielectric structure  150  therefore will not reduce response curve  174  to frequencies below the 5 GHz WLAN frequency band. 
     In order to allow slot  104  to cover frequency F 1  (e.g., a GPS frequency at 1575 MHz), capacitor  154  and filter  152  may be coupled in series between edges  134  and  136  of slot  104 . Component  156  may be invisible to the first harmonic mode of slot  104  associated with curve  174  (e.g., because there is a node at distance  140  from edge  130  in mode  153  as shown in  FIG. 6 ). However, tuning circuit  156  may be visible to frequencies towards the lower end of the fundamental mode of slot  104 . Capacitor  154  may serve to increase the effective electrical length of slot  104  at these frequencies, thus pulling the corresponding response down to frequency F 1 , as shown by curve  170 . Filter  152  may block fundamental mode signal in the 2.4 GHz WLAN band (curve  172 ) from being pulled further down (e.g., because filter  152  exhibits an approximately 0% transmission characteristic in the 2.4 GHz WLAN band, as shown in  FIG. 7 ). In this way, a single rectangular slot  104  may be configured to cover all three of the 1575 MHz GPS band, the 2.4 GHz WLAN band, and the 5.0 GHz WLAN band. 
     In the example of  FIGS. 6-8 , space constraints within device  10  may make it infeasible for length L to be long enough to be approximately equal to half of a wavelength of the 1575 MHz GPS frequency band. However, in some scenarios there may be sufficient space within device  10  to allow length L to be long enough to be approximately half of the wavelength of operation in the 1575 MHz GPS frequency band. When such space exists, slot antenna  40  may be configured as shown in  FIG. 9  (if desired). 
     As shown in  FIG. 9 , slot  104  may have a length L′ that is greater than length L of  FIG. 6 . Length L′ may be approximately half of the wavelength of signals in the 1575 MHz GPS frequency band. In this scenario, tuning circuit  184  may be coupled between edge  134  and edge  136  of slot  104  at distance  140  from edge  130  (e.g., in place of component  156  of  FIG. 6 ). Tuning circuit  184  may be capable of impacting the radiation characteristics of antenna  40  at standing wave modes for which the electric field within slot  104  (i.e., the voltage across slot  104 ) exhibits an anti-node or maximum magnitude at distance  140  from edge  130  (e.g., fundamental mode  151  or second harmonic  155  as shown in  FIG. 6 ). Tuning circuit  184  may be incapable of affecting the radiation characteristics of antenna  40  at harmonic modes of slot  104  for which the electric field within slot  104  exhibits a node or minimum magnitude at distance  140  from edge  130  (e.g., first harmonic mode  153  as shown in  FIG. 6 ). 
     As shown in  FIG. 9 , tuning circuit  184  may include an inductive circuit such as inductor  180  coupled in series with a notch filter  182  between edges  134  and  136 . Notch filter  182  may have a stop band that overlaps with frequencies in the 1575 GPS band. Inductor  180  may serve to decrease the effective electrical length of slot  104  and therefore increase the corresponding frequency when shorted to edge  136  by notch filter  182  (e.g., at frequencies outside of the stop band of notch filter  182 ). Inductor  180  may have no effect on the electrical length and radiating characteristics of slot  104  when notch filter  182  forms an open circuit (e.g., at frequencies within the stop band of notch filter  182 ). 
     A transmission T that may be exhibited by notch filter  182  of  FIG. 9  as a function of frequency is shown in  FIG. 10 . In the graph of  FIG. 10 , the transmission of notch filter  182  is represented by the transmission characteristic of line  200 . 
     As indicated by line  200 , notch filter  182  may have a stop band that overlaps with frequency F 1  (e.g., frequencies in the GPS band around 1575 MHz). At frequencies outside of the stop band, such as frequencies F 2  and F 3 , notch filter  182  may form a short circuit and may pass signals between inductor  180  and edge  136  of slot  104 . At frequencies within the stop band, such as frequency F 1 , notch filter  182  may form an open circuit and may block signals from flowing between inductor  180  and edge  136  of slot  104 . 
       FIG. 11  is a graph in which antenna performance (standing wave ratio) has been plotted as a function of frequency for antenna  40  having tuning circuit  184  coupled across slot  104 . As shown in  FIGS. 9 and 11 , length L′ of slot  104  may be selected to be approximately one-half of the wavelength corresponding to frequency F 1  (e.g., 1575 MHz). The fundamental mode of slot  104  may therefore support coverage at frequency F 1 , as shown by response curve  170 . The first harmonic mode of slot  104  (e.g., at two times F 1  or approximately 3 GHz) may be sufficiently broad so as to cover frequencies in the 2.4 GHz frequency band, as shown by curve  172 . If desired, dielectric structures such as structure  150  of  FIG. 6  may be formed at various locations within slot  104  to further adjust the first harmonic frequency to cover frequency F 2 . 
     The second harmonic mode of slot  104  may cover a band centered around frequency F 3 ′ (e.g., three times F 1  or approximately 4.5 GHz). This may be too low to sufficiently cover frequencies in the 5 GHz WLAN band. However, at frequency F 3 ′ (e.g., 4.5 GHz) notch filter  182  may short inductor  180  to edge  136  of slot  104  (e.g., because the stop band of notch filter  182  does not overlap frequency F 3 ′). Because the electric field (voltage) magnitude across slot  104  at distance  140  from edge  130  (i.e., the location of inductor  180 ) is an anti-node or maximum for this second harmonic mode, inductor  180  may decrease the effective electrical length of slot  104  at frequency F 3 ′, thereby serving to push the second harmonic mode to higher frequencies within the 5 GHZ WLAN band, as shown by arrow  177 . In this way, the second harmonic of slot  104  may support communications in the 5 GHz WLAN band centered at frequency F 3  (e.g., from 5150 to 5850 MHz), as shown by response curve  174 . Because the stop band of notch filter  182  overlaps with GPS frequency F 1 , inductor  180  may be invisible at frequency F 1  and may thereby not pull the fundamental mode off of frequency F 1 , even though the electric field across slot  104  is a maximum at distance  140  from edge  130  in the fundamental mode. In this way, a single rectangular slot  104  may be configured to cover all three of the 1575 MHz GPS band, the 2.4 GHz WLAN band, and the 5.0 GHz WLAN band (e.g., in scenarios where sufficient space in device  10  is present for slot  104  to have length L′). 
     In the examples of  FIGS. 6 and 9 , antenna  40  is fed using a single feed  95  that handles signals in all three frequency bands of interest. This is merely illustrative. If desired, separate feeds may be used for handling WLAN signals and GPS signals. 
       FIG. 12  is a diagram showing how antenna  40  may be fed using separate feeds. As shown in  FIG. 12 , WLAN transceiver  36  may be coupled to feed  95  over transmission line  92 . A second feed  95 ′ may be coupled across slot  104  (e.g., adjacent to feed  95  or at any other desired location along the length of slot  104 ). Feed  95 ′ may include a positive feed terminal  98 ′ and a ground feed terminal  100 ′. GPS receiver circuitry  42  may be coupled to feed  95 ′ over transmission line  92 ′. For example, signal conductor  96 ′ of transmission line  92 ′ may be coupled to feed terminal  98 ′ whereas ground conductor  94 ′ of transmission line  92 ′ may be coupled to feed terminal  100 ′. 
     A filter such as notch filter  210  may be interposed on transmission line  92  (e.g., on conductor  94  and/or conductor  96 ) between feed  95  and WLAN transceiver  36 . Notch filter  210  may have a stop band that overlaps with the 2.4 GHz and 5 GHz WLAN frequency bands (e.g., similar to as shown by characteristic  162  of  FIG. 7 ). Notch filter  210  may allow signals at WLAN frequencies to pass between transceiver  36  and feed  95  while blocking other signals such as GPS signals. 
     A filter such as low pass filter  212  may be interposed on transmission line  92 ′ (e.g., on conductor  94 ′ and/or conductor  96 ′) between feed  95  and GPS receiver  42 . Low pass filter  212  may have a transfer characteristic similar to as shown by curve  160  of  FIG. 7 . Low pass filter  212  may allow signals at relatively low frequencies such as GPS signals to pass between transceiver  42  and feed  95 ′ while blocking other signals such as WLAN signals. In this way, transceivers  36  and  42  may be sufficiently isolated while communicating using the same slot element  104 . The dual-feed arrangement of  FIG. 12  may be used in combination with a slot having length L and tuning circuit  156  (as shown in  FIG. 6 ) or with a slot having length L′ and tuning circuit  184  (as shown in  FIG. 9 ). Using two separate feeds may, for example, incur less filter loss than the arrangement in  FIGS. 6 and 9  (e.g., because filters  210  and  212  of  FIG. 12  may be 50-Ohm filters and may contribute less loss to the conveyed signals than a triplexer in filter  142  of  FIG. 6 ). 
     The example of  FIGS. 6-12  are merely illustrative. In general, antenna  40  may cover any desired frequency bands. Antenna  40  may cover more than three or fewer than three frequency bands if desired. Curves  170 ,  172 , and  174  of  FIGS. 8 and 11  may have any desired shape (e.g., so that antenna  40  exhibits a desired frequency response in one or more bands). 
     By configuring one or more slot antennas  40  in device  10  (e.g., one or more of antennas  40 - 1 ,  40 - 2 ,  40 - 3 , and  40 - 4  of  FIG. 5 ) using the slot antenna structures of  FIGS. 6-12 , device  10  may perform wireless communications over three or more frequency bands using the same relatively small slot structure  104 . This may, for example, eliminate the need for other antennas in device  10  for covering respective frequency bands and may minimize the amount of volume in device  10  required to cover these bands. This minimization in volume may, for example, allow active area AA of display  14  ( FIG. 4 ) to be maximized, thereby maximizing the area on device  10  with which a user may interact with device  10 , for example. 
     The foregoing is merely illustrative and various modifications can be made by those skilled in the art without departing from the scope and spirit of the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20170926
Publication Date: 20200811
Grant Date: 20200811
Priority Date: 20170926
Inventors: RAJAGOPALAN, HARISH
ROMANO, Pietro
AZAD, Umar
Garrido Lopez, David
ZHANG, LU
GOMEZ ANGULO, RODNEY A.
Martinis, Mario
DI NALLO, CARLO
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/521", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/521", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": false, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04M1/0266", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04M1/026", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q13/10", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/521", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/35", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/50", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 65809303