PATENT DOCUMENT

Publication Number: US-11862838-B2
Application Number: US-202016851812-A
Country: US
Kind Code: B2

Title: Electronic devices having wideband antennas

Abstract:
An electronic device may include a curved cover layer and an antenna. The antenna may include a ground and a resonating element on a curved surface of a substrate. The curved surface may have a curvature that matches that of the cover layer. The resonating element may include first, second, and third arms fed by a feed. The first arm and a portion of the ground may form a loop antenna resonating element. The second arm and the first arm may form an inverted-F antenna resonating element, where a portion of the first arm forms a return path to the antenna ground for the inverted-F antenna resonating element. A gap between the first and second arms may form a distributed capacitance. The third arm may form an L-shaped antenna resonating element. The antenna may have a wide bandwidth from below 2.4 GHz to greater than 9.0 GHz.

Claims:
What is claimed is: 
     
       1. An electronic device comprising:
 a dielectric substrate having a surface; 
 an antenna ground on the surface; 
 a first antenna arm on the surface and coupled to the antenna ground at a grounding location; 
 a second antenna arm on the surface and extending from the first antenna arm; 
 an antenna feed coupled to the antenna ground and configured to feed the first and second antenna arms, wherein:
 the first antenna arm and a portion of the antenna ground extending between the grounding location and the antenna feed form a loop path that is configured to convey radio-frequency signals in a first frequency band, 
 the second antenna arm is configured to convey radio-frequency signals in a second frequency band, and 
 a portion of the first antenna arm forms a return path to the antenna ground for the second antenna arm; 
 
 a gap between the second antenna arm and the portion of the first antenna arm, wherein the gap forms a distributed capacitance that is configured to tune a frequency response of the first antenna arm in the first frequency band; and 
 a dielectric cover layer having a curved interior surface, wherein the first and second antenna arms are configured to radiate through the dielectric cover layer, the surface comprises a curved surface, the first and second antenna arms are disposed between the curved surface of the dielectric substrate and the curved interior surface of the dielectric cover layer, and the curved surface is separated from the curved interior surface by a uniform distance across a lateral area of the first and second antenna arms. 
 
     
     
       2. The electronic device of  claim 1 , further comprising:
 a third antenna arm configured to convey radio-frequency signals in a third frequency band, wherein the antenna feed is configured to feed the third antenna arm. 
 
     
     
       3. The electronic device of  claim 2 , further comprising:
 a conductive trace on the surface, wherein the first antenna arm extends from the conductive trace to the grounding location, the third antenna arm extends from the conductive trace, and the antenna feed is coupled between the antenna ground and the conductive trace. 
 
     
     
       4. The electronic device of  claim 3 , wherein the first antenna arm comprises a first segment extending from the conductive trace along a first longitudinal axis, the second antenna arm comprises a second segment that extends from the first segment, the second segment extends along a second longitudinal axis that is non-parallel with respect to the first longitudinal axis, the third antenna arm comprises a third segment that extends from the conductive trace, and the third segment extends along a third longitudinal axis that is parallel to the first longitudinal axis. 
     
     
       5. The electronic device of  claim 4 , wherein the portion of the first antenna arm comprises fourth and fifth segments, the gap is formed between the fourth segment and the second segment, the fifth segment couples the fourth segment to the grounding location, the third antenna arm comprises a sixth segment that extends from the third segment, and the sixth segment extends along a fourth longitudinal axis that is parallel to the second longitudinal axis. 
     
     
       6. The electronic device of  claim 2 , wherein the third antenna arm is coupled to the antenna ground, the antenna feed being coupled between the first antenna arm and the antenna ground. 
     
     
       7. The electronic device of  claim 6 , wherein the third antenna arm comprises an L-shaped strip. 
     
     
       8. The electronic device of  claim 7 , wherein the second antenna arm is configured to feed the L-shaped strip via near-field electromagnetic coupling. 
     
     
       9. The electronic device of  claim 7 , wherein the first antenna arm and the portion of the antenna ground run around a central opening at the surface, the L-shaped strip being located within the central opening. 
     
     
       10. The electronic device of  claim 2 , wherein the second frequency band is lower than the first frequency band, the third frequency band comprising frequencies that are greater than the first frequency band. 
     
     
       11. An antenna comprising:
 an antenna ground; 
 a loop antenna resonating element configured to resonate in a first frequency band, wherein the loop antenna resonating element extends around a central opening; 
 an inverted-F antenna resonating element configured to resonate in a second frequency band, wherein a portion of the loop antenna resonating element forms a return path to the antenna ground for the inverted-F antenna resonating element; 
 an L-shaped antenna resonating element configured to resonate in a third frequency band, wherein the L-shaped antenna resonating element is disposed within the central opening of the loop antenna resonating element and has a proximal end connected to the antenna ground; and 
 an antenna feed configured to feed the loop antenna resonating element, the inverted-F antenna resonating element, and the L-shaped antenna resonating element. 
 
     
     
       12. The antenna defined in  claim 11 , wherein the L-shaped antenna resonating element extends from a portion of the loop antenna resonating element. 
     
     
       13. The antenna defined in  claim 12 , wherein the L-shaped antenna resonating element extends from a portion of the loop antenna resonating element formed from the antenna ground. 
     
     
       14. The antenna defined in  claim 11 , wherein the first frequency band comprises 5 GHz, the second frequency band comprises 2.4 GHz, and the third frequency band comprises a frequency between 5 GHz and 9 GHz. 
     
     
       15. An antenna comprising:
 an antenna ground; 
 a feed segment separated from the antenna ground by a first gap; 
 a first resonating element arm having a first segment extending from the feed segment, a second segment extending from the first segment at a non-parallel angle with respect to the first segment, and a third segment extending from the second segment to the antenna ground; 
 a second resonating element arm having a fourth segment extending from the first and second segments and having a fifth segment extending from the fourth segment at a non-parallel angle with respect to the fourth segment, wherein the fourth segment extends parallel to the second segment; 
 a second gap between the second segment and the fourth segment; 
 a third resonating element arm having a sixth segment coupled to the feed segment and having a seventh segment that extends from the sixth segment at a non-parallel angle with respect to the sixth segment; and 
 an antenna feed having a positive antenna feed terminal coupled to the feed segment and having a ground antenna feed terminal coupled to the antenna ground, wherein the antenna feed is configured to feed the first, second, and third resonating element arms. 
 
     
     
       16. The antenna defined in  claim 15 , wherein the sixth segment extends from the feed segment parallel to the first segment. 
     
     
       17. The antenna defined in  claim 16 , wherein the seventh segment extends parallel to the fifth segment and is separated from the fifth segment by a third gap. 
     
     
       18. The antenna defined in  claim 17 , wherein the second resonating element arm has an eighth segment that extends from the fifth segment parallel to the third segment. 
     
     
       19. The antenna defined in  claim 15 , wherein the feed segment, the first segment, the second segment, the third segment, and a portion of the antenna ground form a loop antenna resonating element configured to radiate in a first frequency band, the second resonating element arm being configured to radiate in a second frequency band that is different from the first frequency band. 
     
     
       20. The antenna defined in  claim 15 , wherein the sixth segment is coupled to the feed segment at a location between the positive antenna feed terminal and the first segment.

Description:
BACKGROUND 
     This relates to electronic devices, and more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices are often provided with wireless communications capabilities. An electronic device with wireless communications capabilities has wireless communications circuitry with one or more antennas. Wireless transceiver circuitry in the wireless communications circuitry uses the antennas to transmit and receive radio-frequency signals. 
     It can be challenging to form a satisfactory antenna for an electronic device. If care is not taken, the antenna may not perform satisfactorily, may be overly complex to manufacture, or may be difficult to integrate into a device. There is also increasing demand for antennas to handle a greater number of frequency bands. However, space constraints in electronic devices can undesirably limit the bandwidth of the antennas. 
     SUMMARY 
     An electronic device may include a housing having a curved dielectric cover layer. The device may include wireless circuitry with an antenna. The antenna may include an antenna ground and an antenna resonating element formed from conductive traces patterned on a curved surface of a dielectric substrate. The curved surface may have a curvature that matches the curvature of the curved dielectric cover layer. This may ensure that a uniform impedance boundary is present between the antenna and the curved dielectric cover layer across the entire lateral area of the antenna resonating element. 
     The antenna resonating element may include first, second, and third arms that are fed by a single antenna feed. The first arm may be coupled between the antenna feed and the antenna ground. The second arm may extend from the first arm. The first arm and a portion of the antenna ground may form a loop antenna resonating element. The second arm and the first arm may form an inverted-F antenna resonating element, where a portion of the first arm forms a return path to the antenna ground for the inverted-F antenna resonating element. A gap between the second arm and the portion of the first arm may form a distributed capacitance. The distributed capacitance may tune a frequency response of the loop antenna resonating element. 
     The third arm of the antenna resonating element may form an L-shaped antenna resonating element. The third arm may be coupled to the antenna ground or may be coupled to the loop antenna resonating element. The loop antenna resonating element may resonate in a first frequency band. The inverted-F antenna resonating element may resonate in a second frequency band lower than the first frequency band. The L-shaped antenna resonating element may resonate in a third frequency band that includes frequencies higher than the first frequency band. The antenna may have a relatively wide bandwidth such that the antenna exhibits satisfactory antenna efficiency greater than a threshold antenna efficiency across the entire bandwidth (e.g., from below 2.4 GHz to greater than 9.0 GHz). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram of an illustrative electronic device having an antenna in accordance with some embodiments. 
         FIG.  2    is a top view of an illustrative wideband antenna having three antenna arms extending from a feed segment in accordance with some embodiments. 
         FIG.  3    is a top view of an illustrative wideband antenna having first and second arms extending from a feed and a third arm that extends from an antenna ground in accordance with some embodiments. 
         FIG.  4    is a top view of an illustrative wideband antenna having first and second arms extending from a feed and a third arm that is coupled to an antenna ground and that is interposed between the first and second arms and the antenna ground in accordance with some embodiments. 
         FIG.  5    is a plot of antenna performance (voltage standing wave ratio) as a function of frequency for an antenna of the type shown in  FIGS.  2 - 4    in accordance with some embodiments. 
         FIG.  6    is a cross-sectional side view showing how an antenna of the type shown in  FIGS.  2 - 4    may be integrated within an illustrative electronic device in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     An electronic device such as electronic device  10  of  FIG.  1    may be provided with wireless circuitry. The wireless circuitry may include antennas. Electronic device  10  may be a computing device such as a laptop computer, a desktop 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 wristwatch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses, goggles, or other equipment worn on a user&#39;s head such as a head mounted (display) device, or other types of 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, a wireless internet-connected voice-controlled speaker, a wireless base station or access point, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     As shown in  FIG.  1   , device  10  may include control circuitry  12 . Control circuitry  12  may include storage such as storage circuitry  16 . Storage circuitry  16  may include 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. 
     Control circuitry  12  may include processing circuitry such as processing circuitry  14 . Processing circuitry  14  may be used to control the operation of device  10 . Processing circuitry  14  may include on one or more microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), etc. Control circuitry  12  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  16  (e.g., storage circuitry  16  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  16  may be executed by processing circuitry  14 . 
     Control circuitry  12  may be used to run software on device  10  such as satellite navigation applications, 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, control circuitry  12  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  12  include internet protocols, wireless local area network (WLAN) 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 or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols, cellular telephone protocols, MIMO protocols, antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), or any other desired communications protocols. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  18 . Input-output circuitry  18  may include input-output devices  20 . Input-output devices  20  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  20  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  20  may include touch sensors, displays (e.g., touch-sensitive displays), light-emitting components such as displays without touch sensor capabilities, buttons (mechanical, capacitive, optical, etc.), scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, audio jacks and other audio port components, digital data port devices, motion sensors (accelerometers, gyroscopes, and/or compasses that detect motion), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), etc. In some configurations, keyboards, headphones, displays, pointing devices such as trackpads, mice, and joysticks, and other input-output devices may be coupled to device  10  using wired or wireless connections (e.g., some of input-output devices  20  may be peripherals that are coupled to a main processing unit or other portion of device  10  via a wired or wireless link). 
     Input-output circuitry  18  may include wireless circuitry  22  to support wireless communications. Wireless circuitry  22  may include radio-frequency (RF) transceiver circuitry  24  formed from one or more integrated circuits, power amplifier circuitry, low-noise input amplifiers, passive RF components, one or more antennas such as antenna  40 , transmission lines such as transmission line  26 , and other circuitry for handling RF wireless signals. Wireless signals can also be sent using light (e.g., using infrared communications). While control circuitry  12  is shown separately from wireless circuitry  22  in the example of  FIG.  1    for the sake of clarity, wireless circuitry  22  may include processing circuitry that forms a part of processing circuitry  14  and/or storage circuitry that forms a part of storage circuitry  16  of control circuitry  12  (e.g., portions of control circuitry  12  may be implemented on wireless circuitry  22 ). As an example, control circuitry  12  (e.g., processing circuitry  14 ) may include baseband processor circuitry or other control components that form a part of wireless circuitry  22 . 
     Radio-frequency transceiver circuitry  24  may include wireless local area network transceiver circuitry that handles 2.4 GHz and 5 GHz bands for Wi-Fi® (IEEE 802.11) or other WLAN communications bands and may include wireless personal area network transceiver circuitry that handles the 2.4 GHz Bluetooth® communications band or other WPAN communications bands. If desired, radio-frequency transceiver circuitry  24  may handle other bands such as cellular telephone bands, near-field communications bands (e.g., at 13.56 MHz), millimeter or centimeter wave bands (e.g., communications at 10-300 GHz), and/or other communications bands. If desired, radio-frequency transceiver circuitry  24  may include radio-frequency transceiver circuitry for handling communications in unlicensed bands such as Industry, Science, and Medical (ISM) bands, a frequency band around 6 GHz such as a frequency band that includes frequencies from about 5.925 GHz to 7.125 GHz, or other frequency bands up to about 8-9 GHz. 
     Radio-frequency transceiver circuitry  24  may also include ultra-wideband (UWB) transceiver circuitry that supports communications using the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols. Ultra-wideband radio-frequency signals may be based on an impulse radio signaling scheme that uses band-limited data pulses. Ultra-wideband signals may have any desired bandwidths such as bandwidths between 499 MHz and 1331 MHz, bandwidths greater than 500 MHz, etc. The presence of lower frequencies in the baseband may sometimes allow ultra-wideband signals to penetrate through objects such as walls. In an IEEE 802.15.4 system, a pair of electronic devices may exchange wireless time stamped messages. Time stamps in the messages may be analyzed to determine the time of flight of the messages and thereby determine the distance (range) between the devices and/or an angle between the devices (e.g., an angle of arrival of incoming radio-frequency signals). The ultra-wideband transceiver circuitry may operate (i.e., convey radio-frequency signals) in frequency bands such as an ultra-wideband communications band between about 5 GHz and about 8.5 GHz (e.g., a 6.5 GHz UWB communications band, an 8 GHz UWB communications band, and/or at other suitable frequencies). Communications bands may sometimes be referred to herein as frequency bands or simply as “bands.” 
     Wireless circuitry  22  may include one or more antennas such as antenna  40 . In general, radio-frequency transceiver circuitry  24  may be configured to cover (handle) any suitable communications (frequency) bands of interest. Radio-frequency transceiver circuitry  24  may convey radio-frequency signals using antennas  40  (e.g., antennas  40  may convey the radio-frequency signals for transceiver circuitry  24 ). The term “convey radio-frequency signals” as used herein means the transmission and/or reception of the radio-frequency signals (e.g., for performing unidirectional and/or bidirectional wireless communications with external wireless communications equipment). Antennas  40  may transmit the radio-frequency signals by radiating the radio-frequency signals into free space (or to freespace through intervening device structures such as a dielectric cover layer). Antennas  40  may additionally or alternatively receive the radio-frequency signals from free space (e.g., through intervening devices structures such as a dielectric cover layer). The transmission and reception of radio-frequency signals by antennas  40  each involve the excitation or resonance of antenna currents on an antenna resonating element in the antenna by the radio-frequency signals within the frequency band(s) of operation of the antenna. 
     Antennas such as antenna  40  may be formed using any suitable antenna types. For example, antennas in device  10  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, monopole antenna structures, strip antenna structures, dipole antenna structures, hybrids of these designs, etc. Parasitic elements may be included in antennas  40  to adjust antenna performance. If desired, antenna  40  may be provided with a conductive cavity that backs the antenna resonating element of antenna  40  (e.g., antenna  40  may be a cavity-backed antenna such as a cavity-backed slot antenna). 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. In some configurations, different antennas may be used in handling different bands for radio-frequency transceiver circuitry  24 . Alternatively, a given antenna  40  may cover one or more bands. 
     As shown in  FIG.  1   , radio-frequency transceiver circuitry  24  may be coupled to antenna feed  32  of antenna  40  using transmission line  26 . Antenna feed  32  may include a positive antenna feed terminal such as positive antenna feed terminal  34  and may include a ground antenna feed terminal such as ground antenna feed terminal  36 . Transmission line  26  may be formed from metal traces on a printed circuit, cables, or other conductive structures. Transmission line  26  may have a positive transmission line signal path such as path  28  that is coupled to positive antenna feed terminal  34 . Transmission line  26  may have a ground transmission line signal path such as path  30  that is coupled to ground antenna feed terminal  36 . Path  28  may sometimes be referred to herein as signal conductor  28  and path  30  may sometimes be referred to herein as ground conductor  30 . 
     Transmission line paths such as transmission line  26  may be used to route antenna signals within device  10  (e.g., to convey radio-frequency signals between radio-frequency transceiver circuitry  24  and antenna feed  32  of antenna  40 ). Transmission lines in device  10  may include coaxial cables, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Transmission lines in device  10  such as transmission line  26  may be integrated into rigid and/or flexible printed circuit boards. In one suitable arrangement, transmission lines such as transmission line  26  may also include transmission line conductors (e.g., signal conductors  28  and ground conductors  30 ) 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). The multilayer laminated structures may, if desired, be folded or bent in multiple dimensions (e.g., two or three dimensions) and may maintain 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). 
     Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be interposed within the paths formed using transmission lines such as transmission line  26  and/or circuits such as these may be incorporated into antenna  40  (e.g., to support antenna tuning, to support operation in desired frequency bands, etc.). During operation, control circuitry  12  may use radio-frequency transceiver circuitry  24  and antenna(s)  40  to transmit and receive data wirelessly. Control circuitry  12  may, for example, receive wireless local area network communications wirelessly using radio-frequency transceiver circuitry  24  and antenna(s)  40  and may transmit wireless local area network communications wirelessly using radio-frequency transceiver circuitry  24  and antenna(s)  40 . 
     Electronic device  10  may be provided with electronic device housing  38 . Housing  38 , 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. Housing  38  may be formed using a unibody configuration in which some or all of housing  38  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure covered with one or more outer housing layers). Configurations for housing  38  in which housing  38  includes support structures (a stand, leg(s), handles, frames, etc.) may also be used. In one suitable arrangement that is described herein as an example, housing  38  includes a curved dielectric cover layer. Antenna  40  may transmit radio-frequency signals through the curved dielectric cover layer and/or may receive radio-frequency signals through the curved dielectric cover layer. 
     In practice, the number of frequency bands that are used to convey radio-frequency signals for device  10  tends to increase over time. In some scenarios, device  10  may include a different respective antenna  40  for handling each of these bands. However, increasing the number of antennas  40  in device  10  may consume an undesirable amount of space, power, and other resources in device  10 . If desired, a given antenna  40  in device  10  may handle communications in multiple frequency bands to optimize resource consumption within device  10 . In one suitable arrangement that is described herein as an example, a given antenna  40  in device  10  may be configured to handle WLAN frequency bands at 2.4 GHz and 5.0 GHz, unlicensed bands around 6 GHz (e.g., between 5.925 and 7.125 GHz), and/or UWB communications bands at 6.5 GHz and 8.0 GHz. However, it can be challenging to provide an antenna  40  with structures that exhibit sufficient bandwidth to cover each of these frequency bands (e.g., from below 2.4 GHz to above 9.0 GHz) with satisfactory antenna efficiency, particularly when the size of the antenna is constrained by the form factor of device  10 . 
       FIG.  2    is a diagram of an illustrative antenna  40  that may exhibit a sufficiently wide bandwidth so as to cover each of these frequency bands with satisfactory antenna efficiency. As shown in  FIG.  2   , antenna  40  may include an antenna resonating element such as antenna resonating element  46  and ground structures such as antenna ground  42 . Antenna resonating element  46  may sometimes be referred to herein as antenna radiating element  46  or antenna element  46 . Antenna ground  42  may sometimes be referred to herein as ground plane  42  or ground structures  42 . 
     Antenna resonating element  46  and antenna ground  42  may be formed from conductive traces patterned onto a lateral surface such as surface  45  of an underlying dielectric substrate such as dielectric substrate  44 . Dielectric substrate  44  may sometimes be referred to herein as dielectric support structure  44 , dielectric carrier  44 , or antenna carrier  44 . Dielectric substrate  44  may be formed from plastic, ceramic, or any other dielectric materials. If desired, antenna ground  42  and/or antenna resonating element  46  may be formed from conductive traces patterned onto a flexible printed circuit that is layered over surface  45  of dielectric substrate  44 . Surface  45  may be planar or curved, may have planar and curved portions, or may have any other desired geometry. Examples in which surface  45  is curved are described herein as an example. Surface  45  may be curved in three dimensions about multiple axes if desired (e.g., surface  45  may be spherically curved, aspherically curved, freeform curved, etc.). 
     Antenna  40  may be fed using antenna feed  32 . Antenna feed  32  may be coupled between antenna resonating element  46  and antenna ground  42  (e.g., across gap  58  at surface  45  of dielectric substrate  44 ). For example, antenna resonating element  46  may have a feed segment such as feed segment  72 . Feed segment  72  may extend along a corresponding longitudinal axis (e.g., a longitudinal axis oriented parallel to the X-axis of  FIG.  2   ) and may be separated from antenna ground  42  by gap  58 . Positive antenna feed terminal  34  of antenna feed  32  may be coupled to feed segment  72  whereas ground antenna feed terminal  36  is coupled to antenna ground  42  (e.g., at opposing sides of gap  58 ). 
     Antenna resonating element  46  may have multiple arms or branches. In the example of  FIG.  2   , antenna resonating element  46  includes a first arm (branch)  52  extending from feed segment  72 , a second arm (branch)  50  extending from first arm  52 , and a third arm  48  extending from feed segment  72 . Arms  52 ,  50 , and  48  may sometimes be referred to herein as antenna resonating element arms or antenna arms. 
     As shown in  FIG.  2   , first arm  52  may have a first segment  74  extending from an end of feed segment  72  (e.g., first segment  74  may have a first end at the end of feed segment  72  that is opposite to antenna feed  32 ). First segment  74  may extend at a non-parallel angle (e.g., a perpendicular angle) with respect to feed segment  72  (e.g., the longitudinal axis of first segment  74  may extend parallel to the Y-axis of  FIG.  2    and perpendicular to the longitudinal axis of feed segment  72 ). First arm  52  may have a second segment  76  extending from an end of first segment  74  (e.g., first segment  74  may have a second end opposite feed segment  72 , and second segment  76  may have a first end at the second end of first segment  74 ). Second segment  76  may extend at a non-parallel angle (e.g., a perpendicular angle) with respect to first segment  74  (e.g., the longitudinal axis of second segment  76  may extend parallel to the X-axis and feed segment  72 , and may extend perpendicular to the longitudinal axis of first segment  74  of  FIG.  2   ). First arm  52  may also have a third segment  78  extending from an end of second segment  76  (e.g., second segment  76  may have a second end opposite first segment  74 , and third segment  78  may have a first end at the second end of second segment  76 ). Third segment  78  may extend at a non-parallel angle (e.g., a perpendicular angle) with respect to second segment  76  (e.g., the longitudinal axis of third segment  78  may extend parallel to the Y-axis and the longitudinal axis of first segment  74  of  FIG.  2   ). Third segment  78  may have a second end opposite second segment  76 . The second end of third segment  78  may be coupled to antenna ground  42  (e.g., at a grounding location). This may configure first arm  52  to form a loop-shaped path  56  (with feed segment  72  and antenna ground  42 ) for antenna currents flowing between positive antenna feed terminal  34  and ground antenna feed terminal  36 . Loop-shaped path  56  may run around central opening  77  at surface  45  of dielectric substrate  44 . 
     Second arm  50  may have a first segment  80  extending from the second end of segment  74  of first arm  52  and extending from the first end of segment  76  of first arm  52  (e.g., first segment  80  of second arm  50  may have a first end at the ends of segments  74  and  76  of first arm  52 ). First segment  80  of second arm  50  may extend parallel to segment  76  of first arm  52  (e.g., first segment  80  of second arm  50  may extend along a longitudinal axis oriented parallel to the longitudinal axis of segment  76  of first arm  52 ). Second arm  50  may have a second segment  82  extending from an end of first segment  80  to tip  84  of second arm  50  (e.g., first segment  80  may have a second end at second segment  82  of second arm  50 ). Second segment  82  of second arm  50  may extend at a non-parallel angle with respect to first segment  80  of second arm  50  (e.g., along a longitudinal axis parallel to the Y-axis). First segment  80  of second arm  50  may be separated from segment  76  of first arm  52  (e.g., along the entire length of first segment  80 ) by gap  64 . Second segment  82  of second arm  50  may also be separated from segment  78  of first arm  52  by gap  64  if desired. Gap  64  may form a distributed capacitance along the length of first segment  80  of second arm  50  (e.g., a distributed capacitance between segment  80  of second arm  50  and segment  76  of first arm  52 ). The distributed capacitance formed by gap  64  may be used to tune the frequency response of first arm  52  and/or second arm  50 . 
     Third arm  48  may have a first segment  68  extending from feed segment  72  (e.g., first segment  68  of third arm  48  may have a first end at feed segment  72 ). First segment  68  of third arm  48  may extend at a non-parallel angle (e.g., a perpendicular angle) with respect to feed segment  72  (e.g., the longitudinal axis of first segment  68  of third arm  48  may be oriented parallel to the longitudinal axes of segments  74  and  78  of first arm  52  and segment  82  of second arm  50 ). Third arm  48  may also have a second segment  70  extending from a second end of first segment  68  to tip  66  of third arm  48 . Second segment  70  of third arm  48  may extend at a non-parallel angle (e.g., a perpendicular angle) with respect to first segment  68  (e.g., second segment  70  may extend along a longitudinal axis oriented parallel to the longitudinal axes of feed segment  72 , segment  76  of first arm  52 , and segment  80  of second arm  50 ). In other words, third arm  48  may be an L-shaped strip (e.g., an L-shaped arm) extending from feed segment  72 . A portion of second segment  70  of third arm  48  (e.g., at tip  66 ) may be separated from second arm  50  by gap  62 . 
     During signal transmission, antenna feed  32  receives radio-frequency signals from radio-frequency transceiver circuitry  24  of  FIG.  1   . Corresponding (radio-frequency) antenna currents may flow on antenna resonating element  46  and antenna ground  42 . The antenna currents may radiate the radio-frequency signals (e.g., as wireless signals) that are transmitted into free space. During signal reception, antenna resonating element  46  may receive (wireless) radio-frequency signals from free space. Corresponding antenna currents are then produced on antenna resonating element  46 . The radio-frequency signals corresponding to the antenna currents are then transmitted to radio-frequency transceiver circuitry  24  ( FIG.  1   ) via antenna feed  32 . 
     The lengths of first arm  52 , second arm  50 , third arm  48 , and/or feed segment  72  may be selected so that antenna  40  operates in (handles) desired frequency bands of interest. For example, the length of antenna  40  from positive antenna feed terminal  34  to ground antenna feed terminal  36  through feed segment  72 , segments  74 ,  76 , and  78  of first arm  52 , and antenna ground  42  (e.g., the length of loop path  56 ) may be selected to configure antenna resonating element  46  to resonate in a first frequency band. The length of loop path  56  may, for example, be approximately equal to (e.g., within 15% of) one-half of the effective wavelength corresponding to a frequency in the first frequency band. The effective wavelength is equal to a free space wavelength multiplied by a constant value that is determined based on the dielectric constant of dielectric substrate  44 . The first frequency band may, for example, include frequencies between about 5.0 GHz and 6.0 GHz (e.g., for conveying signals in a 5.0 GHz wireless local area network band and/or unlicensed frequencies within the first frequency band). The first frequency band may sometimes be referred to herein as the midband of antenna  40 . 
     During signal transmission, antenna currents in the first frequency band may flow along loop path  56  (e.g., along the perimeter of the conductive structures forming loop path  56 ). Loop path  56  may radiate corresponding (wireless) radio-frequency signals in the first frequency band. Similarly, during signal reception, radio-frequency signals received from free space in the first frequency band may cause antenna currents in the first frequency band to flow along loop path  56 . In this way, feed segment  72 , segments  74 ,  76 , and  78  of first arm  52 , and the portion of antenna ground  42  extending from segment  78  to ground antenna feed terminal  36  may form a loop antenna resonating element for antenna  40  (e.g., first arm  52  may form part of the loop antenna resonating element). If desired, gap  64  may introduce a (distributed) capacitance to loop path  56  that serves to tune the frequency response of loop path  56  in the first frequency band. Increasing the width of gap  64  may decrease this capacitance whereas decreasing the width of gap  64  may increase the capacitance. Gap  64  may, for example, have a width of 0.01-0.10 mm (e.g., approximately 0.05 mm), 0.01-0.50 mm, greater than 0.50 mm, etc. 
     At the same time, the length of antenna resonating element  46  from positive antenna feed terminal  34  to tip  84  of second arm  50  through feed segment  72 , segment  74  of first arm  52 , and segments  80  and  82  of second arm  50  (e.g., the length of path  60 ) may be selected to configure antenna resonating element  46  to resonate in a second frequency band. The length of path  60  may, for example, be approximately equal to (e.g., within 15% of) one-quarter of the effective wavelength corresponding to a frequency in the second frequency band. The second frequency band may, for example, include frequencies below 2.5 GHz (e.g., for conveying signals in a 2.4 GHz wireless local area network band). The second frequency band may sometimes be referred to herein as the low band of antenna  40 . 
     During signal transmission, antenna currents in the second frequency band may flow along path  60  between positive antenna feed terminal  34  and tip  84  (e.g., along the perimeter of the conductive structures forming path  60  of antenna resonating element  46 ). Path  60  may radiate corresponding (wireless) radio-frequency signals in the second frequency band. Similarly, during signal reception, radio-frequency signals received from free space in the second frequency band may cause antenna currents in the second frequency band to flow along path  60 . Segments  76  and  78  of first arm  52  may form a return path to antenna ground  42  for the antenna currents in the second frequency band (e.g., portions of first arm  52  may form a return path to ground for second arm  50  in the second frequency band while concurrently resonating in the first frequency band with the remainder of loop path  56 ). In this way, second arm  50  and first arm  52  may collectively form an inverted-F antenna resonating element in the second frequency band for antenna  40  (e.g., first arm  52  may form both part of a loop antenna resonating element in the first frequency band and part of an inverted-F antenna resonating element in the second frequency band). If desired, gap  64  may introduce a (distributed) capacitance to second arm  50  that serves to tune the frequency response of path  60  in the second frequency band. 
     In addition, the length of third arm  48  (e.g., path  54 ) may be selected to configure antenna resonating element  46  to resonate in a third frequency band. The length of third arm  48  (e.g., path  54 ) may, for example, be approximately equal to (e.g., within 15% of) one-quarter of the effective wavelength corresponding to a frequency in the third frequency band. The third frequency band may, for example, include frequencies between about 5.0 GHz and 9.0 GHz (e.g., for conveying signals in a 5.0 GHz wireless local area network band, for conveying signals in an unlicensed band such as a frequency band between 5.925 and 7.125 GHz, for conveying signals in a 6.5 GHz UWB communications band, and/or for conveying signals in an 8.0 GHz UWB communications band). The third frequency band may sometimes be referred to herein as the high band of antenna  40 . Third arm  48  may sometimes be referred to herein as the high band arm of antenna  40 . Second arm  50  may sometimes be referred to herein as the low band arm of antenna  40 . First arm  52  may sometimes be referred to herein as the midband arm of antenna  40 . 
     During signal transmission, antenna currents in the third frequency band may flow along path  54  between positive antenna feed terminal  34  and tip  66  (e.g., along the perimeter of the conductive structures forming third arm  48 ). Third arm  48  (e.g., path  54 ) may radiate corresponding (wireless) radio-frequency signals in the third frequency band. Similarly, during signal reception, radio-frequency signals received from free space in the third frequency band may cause antenna currents in the third frequency band to flow along path  54 . In this way, third arm  48  may form a monopole antenna resonating element (e.g., an L-shaped antenna resonating element) in the third frequency band for antenna  40 . If desired, gap  62  may introduce a capacitance to third arm  48  that serves to tune the frequency response of third arm  48  and/or that serves to perform impedance matching for third arm  48  in the third frequency band. 
     When configured in this way, antenna  40  may convey (e.g., transmit and/or receive) radio-frequency signals in each of the first, second, and third frequency bands with satisfactory antenna efficiency. Antenna  40  may, for example, exhibit a wideband response and may exhibit satisfactory antenna efficiency from the lower limit of the second frequency band to the upper limit of the third frequency band (e.g., from below 2.4 GHz to over 9.0 GHz). The example of  FIG.  2    in which third arm  48  extends from feed segment  72  of antenna resonating element  46  is merely illustrative. In another suitable arrangement, feed segment  72  may be omitted and third arm  48  may extend from antenna ground  42 . 
       FIG.  3    is a diagram showing how third arm  48  of antenna  40  may extend from antenna ground  42 . As shown in  FIG.  3   , feed segment  72  of  FIG.  2    may be omitted and positive antenna feed terminal  34  may be coupled to the first end of segment  74  of first arm  52 . Segments  74 ,  76 , and  78  of first arm  52  and the segment of antenna ground  42  from segment  78  to ground antenna feed terminal  36  may form loop path  90 . The length of antenna resonating element  46  from positive antenna feed terminal  34  to ground antenna feed terminal  36  through first arm  52  and antenna ground  42  (e.g., the length of loop path  90 ) may be selected to configure antenna resonating element  46  to resonate in the first frequency band. In this way, first arm  52  and the portion of antenna ground  42  extending from segment  78  to ground antenna feed terminal  36  (e.g., loop path  90 ) may form a loop antenna resonating element for antenna  40  that resonates in the first frequency band. 
     The length of antenna resonating element  46  from positive antenna feed terminal  34  to tip  84  of second arm  50  through segment  74  of first arm  52  and through second arm  50  (e.g., the length of path  92 ) may be selected to configure antenna resonating element  46  to resonate in the second frequency band. Segments  76  and  78  of first arm  52  may form a return path to antenna ground  42  for antenna currents in the second frequency band on second arm  50  (e.g., portions of first arm  52  may form a return path to ground for second arm  50  in the second frequency band while concurrently resonating in the first frequency band with the remainder of loop path  90 ). In this way, second arm  50  and first arm  52  may collectively form an inverted-F antenna resonating element in the second frequency band for antenna  40  (e.g., first arm  52  may form both part of a loop antenna resonating element in the first frequency band and part of an inverted-F antenna resonating element in the second frequency band). Gap  64  may introduce a distributed capacitance that serves to tune the frequency response of loop path  90  in the first frequency band and/or that serves to tune the frequency response of path  92  in the second frequency band. 
     As shown in  FIG.  3   , segment  68  of third arm  48  may be coupled to antenna ground  42  (at a grounding location) located at the side of antenna feed  32  opposite to segment  78  of first arm  52  (e.g., antenna feed  32  may be laterally interposed between segment  68  and segment  78  on dielectric substrate  44 ). The length of third arm  48  (e.g., path  88 ) may be selected to configure antenna resonating element  46  to resonate in the third frequency band. If desired, gap  62  may introduce a capacitance to third arm  48  that serves to tune the frequency response of third arm  48  and/or that serves to perform impedance matching for third arm  48  in the third frequency band. Antenna feed  32  may, for example, indirectly feed antenna currents in the third frequency band for third arm  48  via near-field electromagnetic coupling (e.g., across gap  62 ). 
     The example of  FIG.  3    in which antenna feed  32  is interposed between third arm  48  and segment  78  of first arm  52  is merely illustrative. In another suitable arrangement, third arm  48  may be located within central opening  77  of first arm  52 .  FIG.  4    is a diagram showing how third arm  48  may be located within central opening  77  of first arm  52 . 
     As shown in  FIG.  4   , segment  68  of third arm  48  may be coupled to antenna ground  42  at a location that is laterally interposed between antenna feed  32  and segment  78  of first arm  52  (e.g., third arm  48  may be located within central opening  77  of first arm  52 ). The length of third arm  48  (e.g., path  94 ) may be selected to configure antenna resonating element  46  to resonate in the third frequency band. In the examples of  FIGS.  2 - 4   , all three of arms  52 ,  50 , and  48  share the same antenna feed  32  (e.g., antenna feed  32  feeds radio-frequency signals for each of arms  52 ,  50 , and  48 ). Antenna feed  32  conveys the radio-frequency signals for each of arms  52 ,  50 , and  48  between antenna  40  and transceiver circuitry  24  ( FIG.  1   ) (e.g., antenna feed  32  transmits radio-frequency signals that are received by arms  52 ,  50 , and  48  from free space to transceiver circuitry  24  and antenna feed  32  transmits radio-frequency signals that are received from transceiver circuitry  24  over arms  52 ,  50 , and  48 ). The examples of  FIGS.  2 - 4    are merely illustrative. In general, first arm  52 , second arm  50 , and third arm  48  may have other shapes following any desired paths (e.g., paths having any desired number of curved and/or straight segments and that extend at any desired angles). The edges of the conductive material in antenna resonating element  46  may have any desired shape (e.g., may include any desired number of straight and/or curved portions extending at any desired angles). Antenna resonating element  46  may cover additional frequency bands if desired. 
       FIG.  5    is a plot of antenna performance as a function of frequency for antenna  40  of  FIGS.  2 - 4   . As shown in  FIG.  5   , curve  96  plots antenna performance (e.g., voltage standing wave ratio (VSWR)) as a function of frequency for antenna  40 . As shown by curve  96 , antenna  40  may exhibit response peaks that are below a threshold VSWR value TH from a first frequency F 1  to a second frequency F 2 . Frequency F 1  may, for example, be less than 2.4 GHz. Frequency F 2  may, for example, be greater than 9.0 GHz. Antenna  40  may exhibit satisfactory antenna efficiency at each frequency for which the VSWR of the antenna is below threshold value TH. Antenna  40  may therefore exhibit satisfactory antenna efficiency across bandwidth  98  from frequency F 1  to frequency F 2 . 
     For example, as shown by curve  96 , antenna  40  may exhibit a response peak in first frequency band B 1  between about 5.0 GHz and 6.0 GHz due to the contribution (resonance) of first arm  52  of  FIGS.  2 - 4   . Antenna  40  may also exhibit a response peak in second frequency band B 2  at 2.4 GHz due to the contribution (resonance) of second arm  50  (and first arm  52  in serving as a return path for second arm  50 ). Similarly, antenna  40  may exhibit a response peak in third frequency band B 3  between about 5.0 GHz and 9.0 GHz due to the contribution (resonance) of third arm  48 . At the same time, antenna  40  may exhibit satisfactory antenna efficiency at other frequencies across bandwidth  98 . This may allow antenna  40  to also convey radio-frequency signals at any other desired frequency bands between frequencies F 1  and F 2  with satisfactory antenna efficiency, while also occupying a relatively small amount of space within device  10 . The example of  FIG.  5    is merely illustrative. Curve  96  may have other shapes. Antenna  40  may convey radio-frequency signals in any desired number of frequency bands at any desired frequencies. 
       FIG.  6    is a cross-sectional side view (e.g., as taken in the direction of arrow  86  of  FIGS.  2 - 4   ) showing how antenna  40  may be integrated into device  10 . As shown in  FIG.  6   , dielectric substrate  44  may have a curved surface such as surface  45  and at least one additional surface such as bottom surface  102 . Antenna resonating element  46  may be formed from conductive traces patterned onto surface  45  of dielectric substrate  44 . Antenna ground  42  may be formed from conductive traces patterned onto surface  45  and bottom surface  102  of dielectric substrate  44 . The conductive traces of antenna ground  42  and antenna resonating element  46  may be patterned onto dielectric substrate  44  using a Laser Direct Structuring (LDS) process if desired (e.g., dielectric substrate  44  may be formed from an LDS plastic material). In another suitable arrangement, antenna ground  42  and antenna resonating element  46  may be patterned onto one or more flexible printed circuits that are layered onto surfaces  45  and  102  of dielectric substrate  44 . 
     Antenna ground  42  and dielectric substrate  44  may include a hole or opening such as hole  104 . A fastening structure such as screw  100  may extend through hole  104  to secure antenna ground  42  and dielectric substrate  44  to other device components such as system ground  116 . Screw  100  may be a conductive screw that serves to short antenna ground  42  to system ground  116  (e.g., system ground  116  may form part of the ground plane for antenna  40 ). Screw  100  may be replaced by any desired conductive fastening structures such as a conductive clip, a conductive spring, a conductive pin, a conductive bracket, conductive adhesive, welds, solder, combinations of these, etc. 
     Device  10  may include a dielectric cover layer such as dielectric cover layer  110 . Dielectric cover layer  110  may form part of housing  38  of  FIG.  1    for device  10 . Dielectric cover layer  110  may have an interior surface  112  at the interior of device  10  and may have an exterior surface  114  at the exterior of device  10 . Interior surface  112  and/or exterior surface  114  may be curved surfaces (e.g., three-dimensional curved surfaces that are curved along any desired axes such as spherically curved surfaces, aspherically curved surfaces, freeform curved surfaces, etc.). Interior surface  112  and exterior surface  114  may have the same curvature if desired. Dielectric cover layer  110  may be formed from any desired dielectric materials such as plastic, ceramic, rubber, glass, wood, fabric, sapphire, combinations of these or other materials, etc. 
     Dielectric substrate  44  may be mounted within device  10  such that surface  45  faces dielectric cover layer  110 . Antenna resonating element  46  may be separated from interior surface  112  of dielectric cover layer  110  by distance  106 . Antenna  40  may convey radio-frequency signals  108  through dielectric cover layer  110 . Surface  45  of dielectric substrate  44  may be curved. The curvature of surface  45  may be selected to match the curvature of interior surface  112  of dielectric cover layer  110  (e.g., surface  45  may be a three-dimensional curved surface that is curved along any desired axes such as a spherically curved surface, aspherically curved surface, freeform curved surface, etc.). In other words, an entirety of the lateral area of surface  45  overlapping antenna resonating element  46  may extend parallel to the portion of interior surface  112  overlapping antenna resonating element  46 . This configures antenna resonating element  46  to be separated from interior surface  112  by the same distance  106  across the entire lateral area of antenna resonating element  46  (e.g., across the lateral area of at least arms  52 ,  50  and  70 ). This may ensure that a uniform impedance transition is provided from antenna resonating element  46  through dielectric cover layer  110  and to free space across the entire lateral area of antenna resonating element  46 . This may serve to maximize the antenna efficiency for antenna  40  despite the presence of a curved impedance boundary such as dielectric cover layer  110 . 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20200417
Publication Date: 20240102
Grant Date: 20240102
Priority Date: 20200417
Inventors: ZHANG, LIJUN
WU, JIANGFENG
PASCOLINI, MATTIA
YONG, Siwen
JIANG, YI
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q5/371", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/328", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/371", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q5/10", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/378", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/42", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/378", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/328", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q5/328", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/00", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 75478314