PATENT DOCUMENT

Publication Number: US-10608321-B2
Application Number: US-201715602956-A
Country: US
Kind Code: B2

Title: Antennas in patterned conductive layers

Abstract:
An electronic device may include a substrate and a conductive layer on the substrate. The conductive layer may be patterned to form a first region and a second region that surrounds and defines the shape of the first region. The first region may be formed from a continuous portion of the conductive layer. The second region may include a grid of openings that divides the conductive layer into an array of patches. The first region may form an antenna resonating element for an antenna. The second region may block antenna currents from the antenna resonating element and may be transparent to radio-frequency electromagnetic waves. The openings may have a width that is too narrow to be discerned by the human eye. This may configure the first and second regions to appear as a single continuous conductive layer despite the fact that an antenna resonating element is formed therein.

Claims:
What is claimed is: 
     
       1. Apparatus comprising:
 a dielectric substrate; and 
 a conductive layer on the dielectric substrate that is patterned to form a first region and a second region that surrounds at least some of the first region, wherein the first region forms an antenna resonating element for an antenna and is configured to conduct antenna currents, the second region comprises a grid of openings in the conductive layer and is configured to block the antenna currents, the first region comprises a solid region of the conductive layer, the second region defines edges of the solid region and the antenna resonating element, the conductive layer is continuous and free from openings within the solid region and between the edges of the antenna resonating element, the second region includes an array of conductive patches that are separated by the grid of openings, and the second region is transparent to radio-frequency signals. 
 
     
     
       2. The apparatus defined in  claim 1 , wherein the openings in the grid have a lateral surface area, the second region has a total lateral surface area that includes the lateral surface area of the openings, and a ratio of the lateral surface area of the openings to the total lateral surface area of the second region is less than 20%. 
     
     
       3. The apparatus defined in  claim 2 , wherein the antenna comprises a loop antenna, the antenna resonating element comprises a loop antenna resonating element formed from the first region of the conductive layer, and the second region of the conductive layer comprises a first portion that surrounds the loop antenna resonating element and a second portion that is surrounded by the loop antenna resonating element. 
     
     
       4. The apparatus defined in  claim 1 , wherein the plurality of conductive patches comprises conductive patches selected from the group consisting of:
 hexagonal conductive patches, rectangular conductive patches, triangular rectangular patches, circular conductive patches, and elliptical conductive patches. 
 
     
     
       5. The apparatus defined in  claim 1 , wherein each of the openings in the grid has a width that is less than 100 microns. 
     
     
       6. The apparatus defined in  claim 5 , wherein each of the conductive patches in the plurality of conductive patches has a maximum lateral dimension that is greater than 0.1 mm and less than 5 mm. 
     
     
       7. The apparatus defined in  claim 6 , wherein the dielectric substrate comprises a glass window. 
     
     
       8. The apparatus defined in  claim 1 , wherein the openings in the grid of openings have a lateral surface area, the second region has a total lateral surface area that includes the lateral surface area of the openings, and a ratio of the lateral surface area of the openings to the total lateral surface area of the second region is between 0.1% and 10%. 
     
     
       9. The apparatus defined in  claim 1 , wherein the antenna comprises an inverted-F antenna having an antenna ground, the antenna resonating element comprises an inverted-F antenna resonating element arm formed from the solid region, and the solid region forms at least part of the antenna ground for the inverted-F antenna. 
     
     
       10. The apparatus defined in  claim 1 , wherein the antenna comprises a dipole antenna having first and second feed terminals, the antenna resonating element comprises first and second dipole antenna resonating element arms formed from the solid region, the first feed terminal is coupled to the first dipole antenna resonating element arm, the second feed terminal is coupled to the second dipole antenna resonating element arm, and the array of conductive patches in the second region surrounds the first and second dipole antenna resonating element arms in the conductive layer. 
     
     
       11. The apparatus defined in  claim 1 , wherein the dielectric substrate has opposing first and second surfaces, the conductive layer is formed on the first surface, the antenna comprises an antenna ground formed on the second surface, the antenna comprising a patch antenna, and the antenna resonating element comprises a patch antenna resonating element formed from the solid region. 
     
     
       12. The apparatus defined in  claim 1 , wherein each conductive patch in the array of conductive patches has a maximum lateral dimension that is between 0.1 mm and 5 mm. 
     
     
       13. The apparatus defined in  claim 1 , wherein the array of conductive patches comprises first and second sets of conductive patches, each of the conductive patches in the first set has a first shape, and each of the conductive patches in the second set has a second shape that is different from the first shape. 
     
     
       14. The apparatus defined in  claim 13 , wherein the first set of conductive patches is arranged in a first set of rows and a first set of columns, the second set of conductive patches is arranged in a second set of rows and a second set of columns, the first set of rows is offset with respect to the second set of rows, and the first set of columns is offset with respect to the second of columns. 
     
     
       15. The apparatus defined in  claim 1 , wherein the second region defines at least first, second, and third edges of the solid region, the first edge extending parallel to the third edge, and the second edge extending perpendicular to the first and third edges. 
     
     
       16. The apparatus defined in  claim 1 , wherein the first region has a first reflectivity to visible light and the second region has a second reflectivity to visible light that is within 20% of the first reflectivity. 
     
     
       17. The apparatus defined in  claim 1 , wherein the apparatus comprises an electronic device, the conductive layer comprising a conductive housing wall for the electronic device.

Description:
BACKGROUND 
     This relates generally to electronic devices and, more particularly, to electronic devices with wireless communications circuitry. 
     Electronic devices often include wireless circuitry with antennas. For example, cellular telephones, computers, and other devices often contain antennas for supporting wireless communications. 
     It can be challenging to form electronic device antenna structures with desired attributes. In some wireless devices, the presence of conductive structures such as conductive housing structures can influence antenna performance. Antenna performance may not be satisfactory if the housing structures are not configured properly and interfere with antenna operation. Device size can also affect performance. It can be difficult to achieve desired performance levels in a compact device, particularly when the compact device has conductive housing structures. 
     It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices such as electronic devices that include conductive housing structures. 
     SUMMARY 
     An electronic device may be provided with wireless circuitry. The wireless circuitry may include an antenna and transceiver circuitry. The antenna may include an antenna resonating element, an antenna ground, and an antenna feed having first and second feed terminals. The transceiver circuitry may be coupled to the antenna feed over a radio-frequency transmission line. 
     The electronic device may include a dielectric substrate and a conductive layer formed on the dielectric substrate. The conductive layer may include a conductive housing wall for the electronic device, a metal trace on a printed circuit board, a metal coating on a glass substrate, or any other desired conductive layer in the device. The conductive layer may be patterned to form a first region and a second region that surrounds at least some of the first region (e.g., that defines at least one edge of the first region). The first region may be formed from a continuous (solid) portion of the conductive layer that is free from openings. The second region may include a grid of openings in the conductive layer that divides the conductive layer into an array of conductive patches. The first region of the conductive layer may be coupled to the first feed terminal and may form the antenna resonating element for the antenna. The second antenna feed terminal may be coupled to the antenna ground. Antenna currents may flow through the first region of the conductive layer and the antenna ground. 
     The second region of the conductive layer may be configured to block the antenna currents and may be transparent to radio-frequency electromagnetic signals. This may allow the antenna to exhibit satisfactory antenna efficiency (e.g., antenna efficiency similar to that of an antenna having a resonating element located in free space). For example, the openings in the second region may have a lateral surface area whereas the second region as a whole has a total lateral surface area. A ratio of the lateral surface area of the openings to the total lateral surface area of the second region (e.g., the so-called “etching ratio” of the second region) may be less than 20%, less than 10%, or between 0.1% and 10%, as examples. The conductive patches may have a maximal (greatest) lateral dimension that is between 0.1 and 5 mm. The openings may each have a width that is too narrow to be discerned by the un-aided human eye (e.g., less than 100 microns). This may, for example, allow the first and second regions of the conductive layer to appear to a user of the electronic device as a single continuous piece of conductor despite the fact that an antenna resonating element is formed therein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of illustrative circuitry in an electronic device in accordance with an embodiment. 
         FIG. 2  is a diagram of an illustrative transceiver circuit and antenna in accordance with an embodiment. 
         FIG. 3  is a diagram of an antenna formed from a conductive layer having radio-frequency transparent patterned regions in accordance with an embodiment. 
         FIG. 4  is a perspective view of a radio-frequency transparent region of a conductive layer having a pattern of rectangular patches in accordance with an embodiment. 
         FIG. 5  is a top-down view of a radio-frequency transparent region of a conductive layer having a pattern of hexagonal patches in accordance with an embodiment. 
         FIG. 6  is a top-down view of a radio-frequency transparent region of a conductive layer having a pattern of triangular patches in accordance with an embodiment. 
         FIGS. 7 and 8  are top-down views of a radio-frequency transparent region of a conductive layer having a pattern of round patches in accordance with an embodiment. 
         FIG. 9  is a top-down view of a radio-frequency transparent region of a conductive layer having a pattern of linearly polarizing slots in accordance with an embodiment. 
         FIG. 10  is a plot of illustrative patch and slot dimensions for a radio-frequency transparent patterned region of a conductive layer in accordance with an embodiment. 
         FIG. 11  is a schematic diagram of an illustrative loop antenna that may be used in an electronic device in accordance with an embodiment. 
         FIG. 12  is a top-down view of an illustrative loop antenna formed from a conductive layer having radio-frequency transparent patterned regions in accordance with an embodiment. 
         FIG. 13  is a schematic diagram of an illustrative inverted-F antenna that may be used in an electronic device in accordance with an embodiment. 
         FIG. 14  is a top-down view of an illustrative inverted-F antenna formed from a conductive layer having radio-frequency transparent patterned regions in accordance with an embodiment. 
         FIG. 15  is a schematic diagram of an illustrative dipole antenna that may be used in an electronic device in accordance with an embodiment. 
         FIG. 16  is a top-down view of an illustrative dipole antenna formed from a conductive layer having radio-frequency transparent patterned regions in accordance with an embodiment. 
         FIG. 17  is a perspective view of an illustrative patch antenna that may be used in an electronic device in accordance with an embodiment. 
         FIG. 18  is a perspective view of an illustrative patch antenna formed from a conductive layer having radio-frequency transparent patterned regions in accordance with an embodiment. 
         FIGS. 19 and 20  are perspective views of illustrative electronic devices showing locations at which an antenna of the type shown in  FIGS. 2-18  may be formed in accordance with embodiments. 
         FIG. 21  is a graph of antenna performance (antenna efficiency) for an illustrative antenna of the type shown in  FIGS. 2-18  in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices such as electronic device  10  of  FIG. 1  may be provided with wireless communications circuitry. The wireless communications circuitry may be used to support wireless communications in one or more wireless communications bands. 
     The wireless communications circuitry may include one more antennas. The antennas of the wireless communications circuitry can include loop antennas, inverted-F antennas, strip antennas, planar inverted-F antennas, slot antennas, patch antennas, dipole antennas, monopole antennas, hybrid antennas that include antenna structures of more than one type, or other suitable antennas. The antennas may transmit and/or receive radio-frequency signals within one or more wireless communications bands. The wireless communications bands may, for example, include radio frequencies such as frequencies of 700 MHz or greater. Conductive structures for the antennas may, if desired, be formed from conductive electronic device structures. 
     The conductive electronic device structures may include conductive housing structures. As examples, the housing structures may include peripheral structures such as peripheral conductive structures that run around the periphery of an electronic device. The peripheral conductive structure may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device housing, may have portions that extend upwards from an integral planar rear housing (e.g., to form vertical planar sidewalls or curved sidewalls), and/or may form other housing structures. 
     Antennas may be embedded within the conductive electronic device structures. A grid of slots or openings may be formed in the conductive electronic device structures to form a pattern or array of conductive patches that are separated by the slots. The slots may have a width such that the region of the conductive electronic device structures in which the slots are formed is transparent to radio-frequency signals. Such regions may sometimes be referred to herein as radio-frequency transparent patterned regions of the conductive electronic device structures. The slots may be sufficiently narrow so as to be invisible to the un-aided human eye (e.g., so that the radio-frequency transparent patterned region appears to the un-aided human eye as a single continuous piece of conductor). 
     The antennas may include antenna elements such as one or more antenna resonating elements and an antenna ground plane. The antenna resonating element may be formed from a continuous, un-patterned (slot-free) region of the conductive electronic device structures. Edges of the un-patterned region may be defined by the patterned region. Because the slots in the surrounding patterned region of the conductive electronic device structures are invisible to the un-aided eye, the antenna resonating element and the surrounding patterned region may appear to the un-aided eye as a single continuous piece of conductor. Because the patterned region is transparent at radio frequencies (e.g., the patterned region interacts with electromagnetic waves similar to free space at radio frequencies), the antenna resonating element may operate normally (e.g., with satisfactory antenna efficiency) at radio-frequencies without shorting antenna currents to surrounding conductive electronic device structures. 
     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 wristwatch device, a pendant device, a headphone or earpiece device, a virtual or augmented reality headset 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 is mounted in a kiosk, building, vehicle, or automobile, a wireless access point or base station, a desktop computer, a keyboard, a gaming controller, a computer mouse, a mousepad, a trackpad or touchpad device, equipment that implements the functionality of two or more of these devices, or other electronic equipment. Other configurations may be used for device  10  if desired. The example of  FIG. 1  is merely illustrative. 
     If desired, 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. In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
       FIG. 1  is a schematic diagram showing illustrative components that may be used in device  10 . As shown in  FIG. 1 , device  10  may include control circuitry such as storage and processing circuitry  14 . Storage and processing circuitry  14  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  14  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  14  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  14  may be used in implementing communications protocols. Communications protocols that may be implemented using storage and processing circuitry  14  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  16  may include input-output devices  18 . Input-output devices  18  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  18  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  18  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, motion sensors (accelerometers), capacitance sensors, proximity sensors, fingerprint sensors (e.g., a fingerprint sensor integrated with a button), etc. 
     Input-output circuitry  16  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  20  for handling various radio-frequency communications bands. For example, circuitry  34  may include transceiver circuitry  22 ,  24 , and/or  26 . Transceiver circuitry  24  may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communications and may handle the 2.4 GHz Bluetooth® communications band. Circuitry  34  may use cellular telephone transceiver circuitry  26  for handling wireless communications in frequency ranges such as a low communications band from 700 to 960 MHz, a low-midband from 1400-1520 MHz, a midband from 1710 to 2170 MHz, and a high band from 2300 to 2700 MHz or other communications bands between 700 MHz and 4000 MHz or other suitable frequencies (as examples). Circuitry  26  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 millimeter wave (e.g., 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 global positioning system (GPS) receiver equipment such as GPS receiver circuitry  22  for receiving GPS signals at 1575 MHz or for handling other satellite positioning data (e.g., GLONASS signals at 1609 MHz). Satellite navigation system signals for receiver  22  are received from a constellation of satellites orbiting the earth. 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 one or more 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, dipole antenna structures, monopole antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical 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. If desired, two or more antennas  40  may be arranged in a phased antenna array that are operated using beam steering techniques (e.g., schemes in which antenna signal phase and/or magnitude for each antenna in an array is adjusted to perform beam steering). Antenna diversity schemes may also be used to ensure that antennas that have become blocked or that are otherwise degraded due to the operating environment of device  10  can be switched out of use and higher-performing antennas used in their place. 
     As shown in  FIG. 2 , transceiver circuitry  20  in wireless circuitry  34  may be coupled to antenna feed  42  using radio-frequency transmission line  44 . Antenna feed  42  may include a positive antenna feed terminal such as positive antenna feed terminal  46  and may include a ground antenna feed terminal such as ground antenna feed terminal  48 . Transmission line  44  may be formed from metal traces on a printed circuit or other conductive structures and may have a positive transmission line signal path such as path  50  that is coupled to terminal  46  and a ground transmission line signal path such as path  52  that is coupled to terminal  48 . 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. 2  is merely illustrative. 
     Transmission line paths such as path  44  may be used to route antenna signals within device  10 . Transmission line  44  may include coaxial cable paths, 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, or any other desired radio-frequency transmission line structures. Filter circuitry, switching circuitry, impedance matching circuitry, and other circuitry may be coupled to antenna  40  (e.g., to support antenna tuning, to support operation in desired frequency bands, etc.). 
     If desired, optional impedance matching circuitry  54  may be interposed on path  44 . Impedance matching circuitry  54  may include fixed and/or tunable components. For example, circuitry  54  may include a tunable impedance matching network formed from components such as inductors, resistors, and capacitors that are used in matching the impedance of antenna structures  40  to the impedance of transmission line  44 . If desired, circuitry  54  may include a band pass filter, band stop filter, high pass filter, and/or low pass filter. Components in matching circuitry  54  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. In scenarios where matching circuitry  54  is adjustable, control circuitry  14  may provide control signals that adjust the impedance provided by matching circuitry  54 , for example. Matching network  54  and/or other tunable components coupled to antenna  40  may be adjusted (e.g., using control signals provided by control circuitry  14 ) to cover different desired communications bands. 
     If care is not taken, the presence of conductive structures such as conductive housing structures can influence the performance of antenna  40 . Antenna performance may not be satisfactory if the housing structures are not configured properly and interfere with (e.g., electromagnetically shield or block) antenna operation.  FIG. 3  is a diagram showing how antenna  40  may be formed using conductive structures within device  10 . 
     As shown in  FIG. 3 , electronic device  10  may include a conductive device structure such as conductive layer  60 . If desired, conductive layer  60  may be formed on a dielectric substrate. Conductive layer  60  may include a metal trace, metal foil, stamped sheet metal, a conductive coating on the dielectric substrate, a conductive portion of housing  12  ( FIG. 1 ), or any other desired conductive structure. Conductive layer  60  may include, for example, copper, aluminum, stainless steel, silver, gold, nickel, tin, other metals or metal alloys, or any other desired conductive materials. 
     Conductive layer  60  may be patterned to form a radio-frequency transparent region such as region  62  and a continuous region such as region  64 . Slots or openings may be formed in conductive layer  60  within region  62 . The slots in region  62  may be arranged in a grid pattern, for example. The slots in region  62  may for example, extend completely through the thickness of conductive layer  62  and may divide conductive layer  60  into a pattern or array of conductive patches within region  62 . Continuous region  64  may be formed from a single continuous portion of conductive layer  60  (e.g., region  64  may be formed from a solid portion of conductive layer  60  that is free from slots or openings). Region  62  may therefore sometimes be referred to herein as patterned region  62  whereas region  64  is sometimes referred to herein as un-patterned region  64 . 
     Each of the conductive patches in patterned region  62  may be separated from other conductive patches in patterned region  62  by a corresponding slot in conductive layer  60 . Patterned region  62  may surround some or all of un-patterned region  64  (e.g., at least one edge or at least part of the outline of un-patterned region  64  may be defined by patterned region  62 ). For example, one or more of the slots within patterned region  62  may define the shape (e.g., the edges or outline) of un-patterned region  64  within conductive layer  60 . 
     If care is not taken, conductive structures such as metal may block or otherwise interfere with the transmission or reception of radio-frequency signals by antenna  40 . The slots in patterned region  62  of conductive layer  60  may configure patterned region  62  to be transparent to radio-frequency electromagnetic signals (e.g., so that radio-frequency signals pass through patterned region  62  without being blocked by conductive layer  60 ). For example, the dimensions, shapes, and arrangement of the slots and the conductive patches within patterned region  62  may be selected to allow radio-frequency signals to freely pass through conductive layer  60  without being blocked. In contrast, continuous metal structures such as un-patterned region  64  of conductive layer  60  may be opaque to radio-frequency signals. Patterned region  62  may sometimes be referred to herein as radio-frequency transparent region  62  or radio-frequency transparent patterned region  62  of conductive layer  60 . Un-patterned region  64  may sometimes be referred to herein as continuous region  64  or solid region  64  of conductive layer  60 . 
     Antenna  40  may include antenna elements such as an antenna resonating element, an antenna ground, and antenna feed  42 . The antenna resonating element may be coupled to positive antenna feed terminal  46  whereas the antenna ground is coupled to ground antenna feed terminal  48 . The antenna resonating element may have dimensions (e.g., a particular shape, perimeter, and/or area) that support an antenna resonance within one or more desired frequency bands (e.g., for performing wireless communications in those frequency bands). 
     As shown in  FIG. 3 , positive antenna feed terminal  46  may be coupled to conductive layer  60  within un-patterned region  64  so that un-patterned region  64  of conductive layer  60  forms the antenna resonating element for antenna  40 . Ground antenna feed terminal  48  of antenna  40  may be coupled to antenna ground  70 . Antenna ground  70  may include conductive portions of housing  12 , conductive layers on a substrate such as a printed circuit board, conductive components within device  10 , or any other desired conductive components. If desired, antenna ground  70  may be formed from one or more un-patterned regions  64  of conductive layer  60 . 
     Un-patterned region  64  of conductive layer  60  may receive radio-frequency signals from transceiver circuitry  20  over positive feed terminal  46 . Corresponding antenna currents may flow through un-patterned region  64 . Patterned region  62  of conductive layer  60  may form an open circuit at radio-frequencies so that the antenna currents do not flow over patterned region  62  (e.g., patterned region  62  may block the antenna currents from flowing into region  62 ). Antenna currents flowing through un-patterned region  64  and antenna ground  70  may generate wireless signals that are radiated by antenna  40 . Because patterned region  62  is transparent to radio-frequency signals, patterned region  62  interacts with the wireless signals similar to free space, and the wireless signals may be freely radiated from antenna  40  to external communications equipment. Similarly, antenna  40  may receive wireless signals from external communications equipment. The received wireless signals may generate antenna currents on un-patterned region  64  and antenna ground  70  that are then conveyed to transceiver  20  over transmission line  44 . If region  62  were not transparent to radio-frequency signals, antenna  40  would exhibit an unsatisfactory (degraded) antenna efficiency (e.g., because the antenna currents would be shorted to the entirety of conductive layer  60 ). By forming antenna  40  using a continuous region  64  defined by patterned region  62  of conductive layer  60 , antenna  40  may freely transmit and receive radio-frequency signals with satisfactory antenna efficiency (e.g., antenna efficiency comparable to that of an antenna having an antenna resonating element formed in a free space environment). 
     If desired, the dimensions and shape of the slots and the corresponding conductive patches within patterned region  62  of conductive layer  60  may be selected so that the slots are invisible or indiscernible to the unaided human eye. For example, the slots may be narrower than is resolvable to the unaided human eye at a predetermined distance from conductive layer  60  (e.g., a distance of 1 meter, 1 centimeter, 10 centimeters, etc.). This may allow the entirety of patterned region  62  and un-patterned region  64  to appear to a user as a single continuous (solid) piece of metal, thereby obscuring the potentially unsightly antenna  40  from the user&#39;s view. This may serve to enhance the aesthetic properties of conductive layer  60  to the user (particularly in scenarios where conductive layer  60  is formed at the exterior of device  10 , for example). 
     As an example, the optical characteristics of regions  62  and  64  of conductive layer  60  may be characterized by the reflectivity, absorption, and transmission of visible light by regions  62  and  64 . Region  62  may exhibit a first reflectivity, first absorptivity, and first transmissivity, whereas region  64  exhibits a second reflectivity, second absorptivity, and second transmissivity for visible light. In order to appear to the unaided eye as a single continuous piece of conductor, region  62  may have a first reflectivity, first absorptivity, and/or first transmissivity that are within a predetermined margin of the second reflectivity, second absorptivity, and/or second transmissivity associated with region  64 , respectively (e.g., within a margin of 10%, 20%, 10-20%, 20-30%, 5%, 2%, 1-10%, etc.). 
     The example of  FIG. 3  is merely illustrative. If desired, multiple un-patterned regions such as region  64  may be formed within conductive layer  60 . Each of the un-patterned regions in conductive layer  60  may be separated by some or all of patterned region  62 . Antenna  40  may include multiple resonating elements formed from different un-patterned regions in conductive layer  60  if desired. In another suitable arrangement, multiple antennas  40  may be formed using different un-patterned regions in conductive layer  60 . 
       FIG. 4  is a perspective view showing patterned region  62  of conductive layer  60 . As shown in  FIG. 4 , conductive layer  60  may be formed on a substrate such as dielectric substrate  80 . Substrate  80  may be formed from plastic, polymer, glass, ceramic, epoxy, foam, a rigid or flexible printed circuit board substrate, or any other desired materials. Conductive layer  60  may include a conductive coating or metal coating, sheet metal, conductive or metal traces, or any other desired conductive structures formed on a surface of substrate  80 . Substrate  80  may have a thickness (height)  82 . Conductive layer  60  may have a thickness (height)  74 . Thickness  82  of substrate  80  may be, for example, between 6 mm and 1 mm, between 5.5 mm and 2 mm, between 5 mm and 3 mm, less than 1 mm, between 0.1 mm and 2 mm, or greater than 6 mm (e.g., 1 cm, 5 cm, 10 cm, etc.). Thickness  74  of conductive layer  60  may be, for example, between 100 nm and 10 nm, between 75 nm and 25 nm, less than 25 nm, greater than 100 nm, between 0.1 mm and 0.5 mm, between 500 microns and 1 mm, between 1 and 500 microns, or greater than 1 mm. In practice, lesser thicknesses  74  may provide region  62  of layer  60  with a greater amount of radio-frequency transparency than when greater thicknesses  74  are used, whereas lesser thicknesses  74  may increase the difficulty of manufacturing layer  60  relative to when greater thicknesses  74  are used, for example. 
     As shown in  FIG. 4 , a grid of slots such as slots  66  may be formed in conductive layer  60  within patterned region  62 . As examples, slots  66  may be formed in conductive layer  60  by etching (e.g., laser etching), stripping, cutting, or otherwise removing conductive material in layer  60  from the surface of substrate  80 , or may be formed upon deposition of conductive layer  60  onto the surface of substrate  80 . Slots  66  (sometimes referred to as gaps, notches, or openings) may extend through thickness  74  of conductive layer  60 , thereby exposing substrate  80  through layer  60 . If desired, slots  66  may be filled with a dielectric material such as plastic, glass, ceramic, epoxy, adhesive, integral portions of substrate  80 , or other dielectric materials. If desired, slots  66  may be filled with air. In another suitable arrangement, slots  66  may be formed from integral portions of conductive layer  60  that have been processed to no longer be conductive (e.g., using oxidation or other processing techniques). In yet another suitable arrangement, slots  66  may extend only partially through the thickness  74  of layer  60  (e.g., some of the conductive material in layer  60  may remain within slots  66  if desired). 
     In the example of  FIG. 4 , slots  66  are formed within layer  60  in a rectangular grid pattern in which slots  66  divide conductive layer  60  into multiple rectangular conductive patches  72  (e.g., the edges of conductive patches  72  may be defined by slots  66 ). If desired, conductive patches  72  may be arranged in an array having aligned rows and columns. In another suitable arrangement, the rows and/or columns of patches  72  in the array may be misaligned (e.g., the even numbered rows or columns of patches  72  may all be aligned with each other whereas the odd numbered rows or columns of patches  72  are all aligned with each other but misaligned with respect to the even numbered rows and columns). Each of the rectangular patches  72  in patterned region  62  may be separated from other rectangular patches  72  and/or from un-patterned portions  64  of layer  60  ( FIG. 3 ) by a corresponding segment of slots  66 . Conductive patches  72  may sometimes be referred to herein as conductive tiles. 
     Patterned region  62  of conductive layer  60  may be defined at least in part by two characteristics: the length  78  of each segment of slots  66  (e.g., the portion of slots  66  separating two adjacent patches  72 ) and the width  76  of each segment of slots  66 . The size of each rectangular (e.g., square) patch  72  may be dependent upon the length  78  and width  76  of each segment of the slots  66 , for example. Each rectangular patch  72  within region  62  may have the same size and dimensions or two or more patches  72  within region  62  may have different sizes or dimensions. Each segment of slots  66  in region  62  may have the same length  78  and width  76  or two or more segments of slots  66  may have different lengths and/or widths. 
     The so-called “gap ratio,” “slot ratio,” or “etching ratio” of region  62  may be defined as the ratio of the lateral surface area of slots  66  within patterned region  62  to the total lateral surface area of patterned region  62  (i.e., the total lateral surface area of patterned region  62  includes the lateral surface area of slots  66  within region  62 ). In the example of  FIG. 4 , the total lateral surface area of region  62  is equal to the product of dimension  88  and dimension  90  (e.g., the sum total of area covered by all of slots  66  and patches  72  in region  62 ). Similarly, the lateral surface area of slots  66  is equal to the product of slot length  78  to slot width  76  times the total number of slot segments in region  62  (adjusting for overlap between each of the segments). 
     As examples, a gap ratio of 0.0 (i.e., 0%) may correspond to a region of conductive layer  60  in which no slots  66  are formed (e.g., un-patterned region  64  of  FIG. 3 ), whereas a gap ratio of 1.0 (i.e., 100%) may correspond to a region in which all of the conductive material has been removed from layer  60 . In other words, as length  78  and width  76  of slots  66  increase or the dimensions of patches  72  decrease, the gap ratio of region  62  increases. 
     In practice, the gap ratio may affect the amount of radio-frequency signals transmitted through region  62  of layer  60  (e.g., the degree to which region  62  is transparent at radio-frequencies or, in other words, the radio-frequency transmissivity of region  62 ). In general, larger gap ratios may increase the radio-frequency transparency of layer  60  while also increasing the visibility of gaps  66  to a user relative to scenarios where smaller gap ratios are used. In order to allow for region  62  to have satisfactory radio-frequency transparency while still appearing as a continuous conductor to a user, patterned region  62  may be formed with a gap ratio selected between 0.1% and 10%, between 0.5% and 5%, less than 20%, between 10% and 20%, or between 1% and 3%, as examples. In order to allow for optimal antenna efficiency, slots  66  may have segment lengths  78  (patches  72  may have widths) that are less than 5 mm and greater than 0.1 mm, for example (e.g., lengths  78  may be between 0.1 and 1 mm, between 1 and 5 mm, between 0.2 and 0.5 mm, etc.). In another suitable arrangement, the greatest (maximum or longest) lateral dimension of patches  72  (e.g., the corner-to-corner length of rectangular patches  72 ) may be between 0.1 mm and 5 mm. The dimensions of patches  72 , thickness  74 , lengths  78 , widths  76 , and/or the particular frequency of operation may affect the radio-frequency transparency of region  62  and thus the efficiency of antenna  40  formed using conductive layer  60 . 
     In order for slots  66  to remain invisible or indiscernible to the un-aided human eye at a predetermined distance (e.g., for region  62  to appear as a continuous piece of conductor), slots  66  may have a width  76  that is less than or equal to the resolving power of the un-aided human eye at the predetermined distance. For example, slots  66  may have widths  76  that are less than 200 microns or less than 100 microns such as a width of 50 microns, 40 microns, 70 microns, between 50 and 70 microns, between 70 and 100 microns, between 20 and 50 microns, between 2 and 5 microns, between 10 and 20 microns, between 1 and 10 microns, less than 1 micron, etc. 
     When configured in this way, patterned region  62  of conductive layer  60  may exhibit a visible light reflectivity, absorptivity, and/or transmissivity that are within 20%, within 10%, within less than 10% (e.g., within 5%, within 2%, etc.), or within 10-20% of the visible light reflectivity, absorptivity, and/or transmissivity of un-patterned region  64  of conductive layer  60 , as examples. Patterned region  62  and un-patterned region  64  of conductive layer  60  may thereby appear to the user of device  10  as a single continuous piece of metal. 
     If desired, optional protective cover layer  83  may be formed over conductive layer  60  (e.g., on a side of layer  60  opposite to substrate  80 ). Protective cover layer  83  may include, for example, a dielectric or polymer coating. Cover layer  83  may mechanically protect layer  60  (e.g., to prevent a user from being able to damage portions of layer  60 ) and/or may protect layer  60  from dust, oils, or other contaminants. If desired, substrate  80  and/or cover layer  83  may be omitted. In this scenario, dielectric adhesive may be formed within slots  66  to bind patches  72  together, for example. 
     The example of  FIG. 4  in which a grid of slots  66  divide conductive layer  60  into an array of rectangular patches  72  is merely illustrative. If desired, slots  66  may divide conductive layer  60  into conductive patches of any desired shape.  FIG. 5  is a top-down view of patterned region  62  in which slots  66  divide conductive layer  60  into an array of hexagonal conductive patches. 
     As shown in  FIG. 5 , each segment of slots  66  in conductive layer  60  may separate two adjacent hexagonal (i.e., six-sided) conductive patches  92  (or may separate patches  92  from an un-patterned region  64  of layer  60 ). In other words, each slot segment may be formed between a corresponding side of two different, adjacent hexagonal patches  92 . Each segment of slots  66  may have slot width  76  and length  78  (e.g., each side of hexagonal patches  92  may have a length equal to length  78 ). Forming region  62  using a hexagonal grid of slots  66  and hexagonal conductive patches  92  may allow for increased antenna efficiency for certain types of antenna resonating elements (i.e., antenna resonating elements formed from un-patterned regions  64 ) relative to the rectangular pattern shown in  FIG. 4 , for example. Each hexagonal patch  92  may have the same size and dimensions within region  62  or two or more patches  92  within region  62  may have different sizes or dimensions. Each side of patches  92  or the maximal lateral dimension of each patch  92  may be, for example, between 0.1 mm and 5 mm. 
       FIG. 6  is a top-down view of patterned region  62  in which a grid of slots  66  divide conductive layer  60  into an array of triangular patches. As shown in  FIG. 6 , each segment of slots  66  in conductive layer  60  may separate two adjacent triangular (i.e., three-sided) conductive patches  102  (or may separate patches  102  from an un-patterned region  64  of layer  60 ). In other words, each slot segment may be formed between a corresponding side of two different, adjacent triangular patches  102 . Triangular patches  102  may be, for example, equilateral triangles. Each segment of slots  66  may have slot width  76  and length  78  (e.g., each side of triangular patches  102  may have a length equal to length  78 ). Each side of triangular patches  102  or the maximal lateral dimension of each triangular patch  102  may be, for example, between 0.1 mm and 5 mm. Forming region  62  using a triangular grid of slots  66  and triangular conductive patches  102  may allow for increased antenna efficiency for certain types of antenna resonating elements relative to the square pattern shown in  FIG. 5  and the hexagonal pattern shown in  FIG. 5 , for example. 
     In the example of  FIGS. 4-6 , each of the conductive patches in patterned region  62  has the same equilateral shape (e.g., each of the sides of each conductive patch is straight and the same length). This is merely illustrative. If desired, patterned region  62  may include different conductive patches having different shapes as defined by curved and/or straight edges.  FIGS. 7 and 8  are top-down views of patterned region  62  in which slots  66  form a pattern of conductive patches of different shapes and having curved and/or straight edges. 
     As shown in  FIG. 7 , slots  66  may divide conductive layer  60  into an array of rounded conductive patches  112  and  110  in conductive layer  60 . In this example, slots  66  my follow curved paths (may have curved shapes) and may separate each rounded patch  112  from adjacent patches  112  and  110  in region  62 . Rounded patches  112  may be, for example, elliptical or circular patches having a diameter (e.g., maximal lateral dimension)  79 . Dimension  79  may be between 0.1 mm and 5 mm, for example. Rounded patches  110  may be, for example, diamond-shaped patches having curved sides (e.g., sides having a radius of curvature equal to the radius of curvature of patches  110 ). Slots  66  may have width  76  throughout region  62 . In the example of  FIG. 7 , the array of conductive patches  112  and  110  may include a first sub-array (set) of patches  112  and a second sub-array (set) of patches  110 . The sub-array of patches  112  may be arranged in aligned rows and columns. Similarly, the sub-array of patches  110  may be arranged in aligned rows and columns. The rows and columns of the sub-array of patches  110  may be offset (e.g., misaligned) with respect to the sub-array of patches  112 . This may, for example, ensure that slots  66  maintain width  76  (e.g., to ensure that region  62  remains radio-frequency transparent and visibly continuous) throughout region  62 . 
     In the example of  FIG. 7 , the sub-array of rounded patches  112  is arranged in aligned rows and columns. In another suitable arrangement, rounded patches  112  may be located in rows where each patch is misaligned with the patches in the previous and subsequent rows, as shown in  FIG. 8 . In the example of  FIG. 8 , slots  66  divide conductive layer  60  into an array of rounded patches  122  in region  62 . The patches  122  in the odd rows of the array may be aligned with each other but misaligned from the patches in the even rows of the array. Each rounded patch  122  may have a diameter  79  (e.g., a maximal lateral dimension between 0.1 mm and 5 mm). In order to ensure that slots  66  maintain width  76  throughout region  62  (e.g., to ensure that region  62  remains radio-frequency transparent and visibly opaque), intervening conductive patches  120  may be formed between every three adjacent rounded patches  122  in the pattern. 
     The examples of  FIGS. 4-8  are merely illustrative. In general, slots  66  may divide conductive layer  60  into conductive patches having any desired shapes, sizes, and dimensions (e.g., slots  66  may define conductive patches having pentagon shapes, octagon shapes, other polygonal shapes, shapes having curved and straight edges, etc.). Different sets of conductive patches of different sizes, shapes, and dimensions may be formed within the same patterned region  62  if desired. For example, one or more of the patterns shown in  FIGS. 4-8  may each be used in the same patterned region  62  and/or may be combined with other patterns. In general, in order to allow patterned region  62  to appear to the un-aided eye as continuous with un-patterned region  64  while optimizing antenna efficiency, slots  66  within patterned region  62  may have a width  76  throughout region  62  that is less than or equal to 100 microns regardless of the specific patch shape and arrangement that is used, for example (e.g., slots  66  may have a width of 100 microns, 50 microns, 70 microns, between 50 and 70 microns, between 70 and 100 microns, between 20 and 50 microns, between 2 and 5 microns, between 10 and 20 microns, between 1 and 10 microns, less than 1 micron, etc.). Similarly, in order to allow for optimal radio-frequency transparency and antenna efficiency, the gap ratio of patterned region  62  may be the same (e.g., less than 20%, less than 10%, between 0.1% and 10%, between 0.5% and 5%, between 1% and 3%, etc.) regardless of the specific patch shape and arrangement that is used. Different conductive patch patterns and arrangements may be more optimal for antenna efficiency and for contributing to the seamless appearance of conductive layer  70  for some types of antennas than other patch patterns and arrangements, for example. 
     If desired, slots  66  may be configured to affect the polarization of electromagnetic signals conveyed using antenna  40 .  FIG. 9  is a top-down view of patterned region  62  in which slots  66  form a linear polarizer for antenna  40 . As shown in  FIG. 9 , slots  66  are formed from a pattern of multiple parallel slot segments in region  62 . Each of slots  66  may have width  76  and may be separated from adjacent slots  66  by distance  130 . Distance  130  may, for example, be approximately equal to dimension  79  of  FIGS. 7 and 8  and/or dimension  78  of  FIGS. 4-6  or may be any other desired distance. By forming slots  66  from multiple parallel segments, slots  66  may be transparent to radio-frequency signals of a particular polarization (e.g., linear polarization angle) and opaque to radio-frequency signals at other polarizations. The particular angle of slots  66  relative to un-patterned region  64  may determine the linear polarization angle of the radio-frequency signals that pass through region  62 . Patterned region  62  having polarizing slots  66  may only transmit radio-frequency signals of the corresponding polarization. In this scenario, antenna  40  may have optimal antenna efficiency when conveying signals at the polarization of slots  66  and may have degraded antenna efficiency for other polarizations. In this way, slots  66  may be configured to allow antenna  40  to only handle radio-frequency signals of a particular polarization. 
       FIG. 10  is a graph of possible dimensions for patterned region  62  (e.g., patterned region  62  as shown in  FIGS. 4-9 ). As shown in  FIG. 10 , width  76  of slots  66  is plotted on the x-axis and the length of the conductive patches defined by slots  66  is plotted on the y-axis. The length of the conductive patches plotted on the y-axis may be, for example, distance  130  ( FIG. 9 ), length  78  of  FIGS. 4-6 , length  79  of  FIGS. 7 and 8 , or the maximal lateral dimension of the conductive patches defined by slots  66 . 
     Curve  140  may define a limit on possible dimensions for the length of the conductive patches given a corresponding width  76  of slots  66  (e.g., dimensions at which a minimum amount of plane wave transmission through layer  60  is obtained). The area  142  between curve  140  and minimum conductive patch length value Y 1  and between minimum gap width value X 1  and maximum gap width value X 2  may represent the satisfactory dimensions for slots  66  and the corresponding conductive patches (e.g., dimensions for which patterned region  62  is sufficiently transparent and for which slots  66  are sufficiently invisible to the unaided eye). Maximum gap width value X 2  may be, for example, the minimum resolvable distance for an un-aided human eye at a given distance from layer  60  (e.g., 100 microns). Widths  76  that are greater than value X 2  may be discernable by the unaided eye and may thereby degrade the aesthetic quality of conductive layer  60  (e.g., such that the user will be able to discern un-patterned region  64  from patterned region  62 ). Minimum gap width value X 1  may be, for example, the minimum width that still allows electromagnetic waves at the corresponding radio frequency to pass through region  62  (e.g., 1 micron, 2 microns, 5 microns, etc.). The length of the conductive patches within region  62  may be selected based on the width  76  of slots  66  to be used, so long as the length falls within region  140 . Minimum length Y 1  may be determined by limits in the manufacturing equipment used to form patterned region  62  or any other desired criteria. As an example, minimum length Y 1  may be 0.1 mm, 0.2 mm, less than 0.1 mm, etc. Maximum length Y 2  may be determined from the intersection of curve  140  with maximum gap width value X 2 . As an example, maximum length Y 2  may be 5 mm, between 1 and 5 mm, 2 mm, 0.5 mm, less than 1 mm, between 5 and 10 mm, etc. 
     Threshold curve  140  may be determined through factory calibration and testing of antenna  40  within conductive layer  60 , for example. In general the shape and location of curve  140  may depend upon the frequency of operation and on the thickness  74  of layer  60  ( FIG. 4 ). In general, smaller thicknesses  74  may raise curve  140  as shown by arrows  144  (thereby reducing minimum width X 1  and increasing maximum length Y 2 ) whereas larger thicknesses  74  may lower curve  140  as shown by arrows  146  (thereby increasing minimum width X 1  and decreasing maximum length Y 2 ). Similarly, lower frequencies of operation may raise curve  140  as shown by arrows  144  whereas higher frequencies may lower curve  140  as shown by arrows  146 . This example is merely illustrative. 
     Antenna  40  may be formed using any desired antenna structures. Antenna  40  may include an antenna resonating element formed from un-patterned region  64  within conductive layer  60  ( FIG. 3 ). For example, antenna  40  may include a resonating element that is formed from loop antenna structures, patch antenna structures, dipole antenna structures, monopole antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, hybrids of these designs, etc. 
       FIG. 11  is a schematic diagram showing how antenna  40  may be formed using loop antenna structures. As shown in  FIG. 11 , antenna  40  may include a loop antenna resonating element  40 L that follows a loop-shaped conductive path. Positive transmission line conductor  50  and ground transmission line conductor  52  of transmission line  44  may be coupled to antenna feed terminals  46  and  48 , respectively. Antenna currents may flow between feed terminals  46  and  48  over the loop-shaped conductive path of antenna resonating element  40 L. The resonant frequency of antenna resonating element  40 L may be inversely proportional to the total length or the enclosed area of antenna resonating element  40 L, for example. 
     The example of  FIG. 11  is merely illustrative. If desired, an optional electrical component  160  may bridge terminals  46  and  48 , thereby “closing” the loop formed by the path of element  40 L. Antenna  40  may sometimes be referred to as a series-fed loop antenna in the absence of electrical component  160  and may sometimes be referred to as a parallel-fed loop antenna in the presence of electrical component  160 . Loop antenna resonating element  40 L may have other shapes if desired (e.g., rectangular shapes, elliptical shapes, shapes with both curved and straight sides, shapes with irregular borders, etc.). 
       FIG. 12  is a top-down view showing how an antenna resonating element such as loop antenna resonating element  40 L of  FIG. 11  may be integrated within conductive layer  60 . As shown in  FIG. 12 , patterned region  62  of conductive layer  60  may define the edges of un-patterned region  64  of conductive layer  60  (e.g., un-patterned region  64  may be surrounded by region  62  and the shape of un-patterned region  64  may be defined by region  62 ). A set of slots  66  in patterned region  62  such as slots  66 E (sometimes referred to herein as edge slots, boundary slots, or border slots) may define the boundary between un-patterned region  64  and patterned region  62  (e.g., the edge of conductive material within un-patterned region  64  may be defined by edge slots  66 E). The conductive patches within patterned region  62  may be separated from un-patterned region  64  by at least a corresponding edge slot  66 E. 
     In the example of  FIG. 12 , un-patterned region  64  follows a loop path between a first end  170  and a second end  172  and forms loop antenna resonating element  40 L. Positive antenna feed terminal  46  may be coupled to end  170  of un-patterned region  64  whereas ground antenna feed terminal  48  is coupled to end  172  of un-patterned region  64 . Ends  170  and  162  of un-patterned region  64  may be isolated by a given edge slot  64 E if desired (e.g., in scenarios where optional element  160  does not bridge feed terminals  46  and  48  as shown in  FIG. 11 ). 
     Patterned region  62  may include a first portion that is enclosed by the loop path of loop antenna resonating element  40 L and a second portion that surrounds the loop path of loop antenna resonating element  40 L, for example. Slots  66  within patterned region  62  may be arranged in a grid that divides conductive layer  60  into an array of conductive patches such as patches  72  (e.g., rectangular patches  72  as shown in  FIG. 4 ). This example is merely illustrative. In general, slots  66  may define patches of any desired dimensions and shapes (e.g., hexagonal patches such as patches  92  of  FIG. 5 , triangular patches  102  of  FIG. 6 , rounded patches such as patches  112  of  FIG. 7  or patches  122  of  FIG. 8 , etc.). In another suitable arrangement, slots  66  may form a polarizer as shown in  FIG. 9 . In general, any desired combination of patches of any different shapes, sizes, and dimensions may be used. 
     Because slots  66  and patches  72  within patterned region  62  are transparent to electromagnetic waves at the operational frequency of loop antenna resonating element  40 L (e.g., at a radio frequency greater than or equal to 700 MHz), patterned region  62  may appear as an open circuit to antenna currents at the operational frequency of resonating element  40 L (e.g., the antenna currents may be blocked from flowing into patterned region  62 ). This may allow the antenna current to flow between terminals  46  and  48  over the conductive loop path of antenna resonating element  40 L (e.g., over the continuous conductive path of un-patterned region  64 ) without shorting to other portions of conductive layer  60 , thereby contributing to the resonance of antenna  40  and the transmission/reception of wireless signals corresponding to the antenna currents with a satisfactory antenna efficiency (e.g., similar to as if element  40 L were formed from a conductor in free space). 
     In the diagram of  FIG. 12 , slots  66  are shown as darkened lines for the sake of clarity. However, in practice, slots  66  may be free of the conductive material of conductive layer  60  and may have a width  76  that is unresolvable by (e.g., invisible to) the un-aided human eye (e.g., less than 100 microns). This may allow all of the conductive patches  72  in patterned region  62  to appear as single continuous portion of conductive material within layer  60 . Similarly, region  62  may appear as a single continuous portion of conductive material with un-patterned portion  64 . In other words, conductive layer  60  may appear to a user as a single continuous piece of conductor (e.g., metal), even though slots  66  and a fully-functioning antenna resonating element  40 L are formed therein. 
     If desired, antenna  40  may be formed using inverted-F antenna structures.  FIG. 13  is a schematic diagram showing how antenna  40  may be formed using inverted-F antenna structures. As shown in  FIG. 13 , antenna  40  may include may include an inverted-F antenna resonating element  40 F and antenna ground (ground plane)  40 G. Antenna resonating element  40 F may have a main resonating element arm such as arm  180 . The length of arm  180  and/or portions of arm  180  may be selected so that antenna  40  resonates at a desired operating frequency. For example, the length of arm  180  may be a quarter of a wavelength at a desired operating frequency for antenna  40 . 
     Main resonating element arm  180  may be coupled to ground  40 G by return (short circuit) path  182 . If desired, an inductor or other component (e.g., an antenna tuning component) may be interposed in path  182  and/or may be coupled in parallel with path  182  between arm  180  and ground  40 G. Main resonating element arm  180  may follow a straight path or may follow a curved or meandering path. 
     Antenna feed  42  may run in parallel to return path  182  between arm  180  and ground  40 G. For example, positive antenna feed terminal  46  of antenna feed  42  may be coupled to feed leg  184  of resonating element  40 F. Ground antenna feed terminal  48  may be coupled to ground  40 G. If desired, feed  42  may be formed at other locations along arm  180  or feed leg  184  may be omitted. If desired, antenna  40  may include more than one resonating arm branch (e.g., to create multiple frequency resonances to support operations in multiple communication bands) or may have other antenna structures (e.g., parasitic antenna resonating elements, tunable components to support antenna tuning, etc.). For example, arm  180  may have left and right branches that extend outwardly from feed  42  and return path  182 . Multiple feeds may be used if desired. 
       FIG. 14  is a top-down view showing how antenna elements such as inverted-F antenna resonating element  40 F and antenna ground  40 G of  FIG. 13  may be integrated within conductive layer  60 . As shown in  FIG. 14 , patterned region  62  of conductive layer  60  may define the edges of un-patterned region  64  of conductive layer  60  (e.g., the shape of un-patterned region  64  may be defined by region  62 ). Edge slots  66 E may define the boundary between un-patterned region  64  and patterned region  62  (e.g., the edges of conductive material within un-patterned region  64  may be defined by edge slots  66 E). The conductive patches within patterned region  62  may be separated from un-patterned region  64  by at least a corresponding edge slot  66 E. 
     In the example of  FIG. 14 , un-patterned region  64  forms inverted-F antenna resonating element  40 F (e.g., main resonating element arm  180 , return path  182 , and feed leg  184 ) and antenna ground  40 G. Positive antenna feed terminal  46  may be coupled to feed leg  184  of un-patterned region  64  whereas ground antenna feed terminal  48  is coupled to end ground  40 G of un-patterned region  64 . Feed leg  184  may be omitted and terminal  46  may be coupled to arm  180  if desired. 
     Slots  66  within patterned region  62  may be arranged in a grid and may divide conductive layer  60  into an array of conductive patches such as patches  72  (e.g., rectangular patches  72  as shown in  FIG. 4 ). This example is merely illustrative. In general, slots  66  may define patches of any desired dimensions and shapes (e.g., hexagonal patches such as patches  92  of  FIG. 5 , triangular patches  102  of  FIG. 6 , rounded patches such as patches  112  of  FIG. 7  or patches  122  of  FIG. 8 , etc.). In another suitable arrangement, slots  66  may form a polarizer as shown in  FIG. 9 . In general, any desired combination of patches of any different shapes, sizes, and dimensions may be used. 
     In the example of  FIG. 14 , patterned region  62  includes a set of larger conductive patches  72 ′ that have a lateral surface area that is greater than the other conductive patches  72  in region  62 . For example, patches  72 ′ may have approximately four times the surface area as patches  72 . When placed at a suitable location in layer  70 , larger patches  72 ′ may have a negligible impact on the efficiency of antenna  40 . In the example of  FIG. 14 , patches  72 ′ may be formed in region  62  between return path  182  and antenna feed  42  without affecting the efficiency of antenna  40 . This example is merely illustrative and, in general, patches  72 ′ may be formed at any desired location relative to resonating element  40 F. Larger patches such as patches  72 ′ within region  62  may serve to increase the visual continuity of region  62  to a user relative to scenarios where only smaller patches such as patches  72  are used, for example. 
     Because slots  66 , patches  72 , and patches  72 ′ within patterned region  62  are transparent to electromagnetic waves at the operational frequency of inverted-F antenna resonating element  40 F, patterned region  62  may appear as an open circuit to antenna currents at the operational frequency of resonating element  40 F. This may allow the antenna current to flow between terminals  46  and  48  and across resonating element  40 F and portions of antenna ground  40 G (e.g., over the continuous conductive path of un-patterned region  64 ) without shorting to other portions of conductive layer  60 , thereby contributing to the resonance of antenna  40  and the transmission/reception of wireless signals corresponding to the antenna currents with a satisfactory antenna efficiency (e.g., similar to as if element  40 F were formed from a conductor in free space). 
     In the diagram of  FIG. 14 , slots  66  are shown as darkened lines for the sake of clarity. However, in practice, slots  66  may be free from the conductive material of conductive layer  60  and may have a width  76  that is unresolvable by (e.g., invisible to) the un-aided human eye (e.g., less than 100 microns). This may allow all of the conductive patches  72  and  72 ′ in patterned region  62  to appear as single continuous portion of conductive material within layer  60 . Similarly, region  62  may appear as a single continuous portion of conductive material with un-patterned portion  64 . In other words, conductive layer  60  may appear to a user as a single piece of conductor (e.g., metal), even though slots  66  and a fully-functioning antenna resonating element  40 F are formed therein. 
     If desired, antenna  40  may be formed using dipole antenna structures.  FIG. 15  is a schematic diagram showing how antenna  40  may be formed using dipole antenna structures. As shown in  FIG. 15 , antenna  40  may include may include a dipole antenna resonating element  40 D. Antenna resonating element  40 D may have first and second arms such as arms  40 D- 1  and  40 D- 2  and may be fed by antenna feed  42 . Positive antenna feed terminal  46  may be coupled to an end of dipole antenna resonating element arm  40 D- 1 . Ground antenna feed terminal  48  may be coupled to an end of dipole antenna resonating element arm  40 D- 2 . The length of arms  40 D- 1  and  40 D- 2  may be selected so that antenna  40  resonates at a desired operating frequency. For example, the length from end  200  of arm  40 D- 1  to end  202  of arm  40 D- 2  may be a half of a wavelength at a desired operating frequency for antenna  40 . Arms  40 D 1  and/or  40 D 2  may follow straight, curved, or meandering paths if desired. 
       FIG. 16  is a top-down view showing how an antenna resonating element such as dipole antenna resonating element  40 D of  FIG. 15  may be integrated within conductive layer  60 . As shown in  FIG. 16 , patterned region  62  of conductive layer  60  may define the edges of un-patterned region  64  of conductive layer  60  (e.g., the shape of un-patterned region  64  may be defined by region  62 ). Edge slots  66 E may define the boundary between un-patterned region  64  and patterned region  62  (e.g., the edges of conductive material within un-patterned region  64  may be defined by edge slots  66 E). The conductive patches within patterned region  62  may be separated from un-patterned region  64  by at least a corresponding edge slot  66 E. 
     In the example of  FIG. 16 , un-patterned region  64  forms dipole antenna resonating element  40 D (e.g., first and second arms  40 D- 1  and  40 D- 2 ). Positive antenna feed terminal  46  may be coupled to arm  40 D- 1  on un-patterned region  64  whereas ground antenna feed terminal  48  is coupled to arm  40 D- 2  on un-patterned region  64 . A given edge slot  66 E may separate (isolate) arm  40 D- 1  from arm  40 D- 2 . 
     Slots  66  within patterned region  62  may be arranged in a grid and may divide conductive layer  60  into an array of conductive patches such as patches  92  (e.g., hexagonal patches  92  as shown in  FIG. 5 ). This example is merely illustrative. In general, slots  66  may define patches of any desired dimensions and shapes (e.g., rectangular patches such as patches  72  of  FIG. 4 , triangular patches  102  of  FIG. 6 , rounded patches such as patches  112  of  FIG. 7  or patches  122  of  FIG. 8 , etc.). In another suitable arrangement, slots  66  may form a polarizer as shown in  FIG. 9 . Hexagonal patches  92  may allow dipole antenna resonating element  40 D to operate at with higher antenna efficiency than other patch shapes, for example. In general, any desired combination of patches of any different shapes, sizes, and dimensions may be used. 
     Because slots  66  and patches  92  within patterned region  62  are transparent to electromagnetic waves at the operational frequency of dipole antenna resonating element  40 D, patterned region  62  may appear as an open circuit to antenna currents at the operational frequency of resonating element  40 D. This may allow antenna current to flow to and from terminals  46  and  48  over the continuous conductive paths formed by un-patterned region  64  without shorting to other portions of conductive layer  60  (e.g., region  62  may serve to block the antenna currents from flowing into region  62 ), thereby contributing to the resonance of antenna  40  and the transmission/reception of wireless signals corresponding to the antenna currents with a satisfactory antenna efficiency (e.g., similar to as if antenna resonating element  40 D were formed from a conductor in free space). 
     In the diagram of  FIG. 16 , slots  66  are shown as darkened lines for the sake of clarity. However, in practice, slots  66  may be free from the conductive material of conductive layer  60  and may have a width  76  that is unresolvable by the un-aided human eye (e.g., less than 100 microns). This may allow all of the conductive patches  92  in patterned region  62  to appear as single continuous portion of conductive material within layer  60 . Similarly, region  62  may appear as a single continuous portion of conductive material with un-patterned portion  64 . In other words, conductive layer  60  may appear to a user as a single piece of conductor (e.g., metal), even though slots  66  and a fully-functioning antenna resonating element  40 D are formed therein. If desired, dipole element  40 D may be modified to form a monopole element by omitting second arm  40 D- 2  and extending the length of arm  40 D- 1  to half of a wavelength of operation for the antenna, for example. 
     In the examples of  FIGS. 11-16 , conductive layer  60  may be formed on a first surface of dielectric substrate  80  and may optionally be covered by dielectric cover layer  83  (e.g., as shown in  FIG. 4  and regardless of the particular shape of the conductive patches in region  62 ). If desired, a portion of the antenna ground for antenna  40  may be formed from conductive traces within substrate  80  or on an opposing second surface of substrate  80 . In this scenario, conductive vias or other conductive structures may extend through substrate  80  to short portions of layer  60  and/or terminal  48  to the conductive traces. In another suitable arrangement, substrate  80  may be omitted. In this scenario, dielectric adhesive may be formed within slots  66  to bind the conductive patches in patterned region  62  together. 
     If desired, antenna  40  may be formed using patch antenna structures.  FIG. 17  is a schematic diagram showing how antenna  40  may be formed using patch antenna structures. As shown in  FIG. 17 , antenna  40  may include may include a patch antenna resonating element  40 P that is separated from and parallel to a ground plane such as antenna ground  40 G. Arm  212  may be coupled between patch antenna resonating element  40 P and positive antenna feed terminal  46  of antenna feed  42 . Ground antenna feed terminal  48  may be coupled to ground plane  40 G. Patch antenna resonating element  40 P may be separated from ground plane  40 G by distance  210 . 
     The example of  FIG. 17  is merely illustrative. If desired, patch antenna resonating element  40 P may have different shapes and orientations (e.g., planar shapes, curved patch shapes, patch element shapes with non-rectangular outlines, shapes with straight edges such as squares, shapes with curved edges such as ovals and circles, shapes with combinations of curved and straight edges, etc.). If desired, impedance matching notches  214  may be formed in patch antenna resonating element  40 P to help match the impedance of element  40 P to the impedance of transmission line  44 . The length of the sides of patch antenna resonating element  40 P may be selected so that antenna  40  resonates at a desired operating frequency. For example, the lengths of the sides of element  40 P may be a half of a wavelength at a desired operating frequency for antenna  40 . 
       FIG. 18  is a perspective view showing how antenna elements such as patch antenna resonating element  40 P of  FIG. 17  may be integrated within conductive layer  60 . As shown in  FIG. 18 , patterned region  62  of conductive layer  60  may define the edges of un-patterned region  64  of conductive layer  60  (e.g., the shape of un-patterned region  64  may be defined by region  62 ). Edge slots  66 E may define the boundary between un-patterned region  64  and patterned region  62  (e.g., the edges of conductive material within un-patterned region  64  may be defined by edge slots  66 E). The conductive patches within patterned region  62  may be separated from un-patterned region  64  by at least a corresponding edge slot  66 E. 
     In the example of  FIG. 18 , conductive layer  60  may be formed on a first surface of substrate  80 . Ground plane  40 G may be formed on the opposing second surface of substrate  80 . Un-patterned region  64  of conductive layer  60  forms patch antenna resonating element  40 P and arm  212 . Positive antenna feed terminal  46  may be coupled to an end of arm  212  of un-patterned region  64  whereas ground antenna feed terminal  48  is coupled to ground plane  40 G on the opposing surface of substrate  80 . 
     Slots  66  within patterned region  62  may be arranged in a grid that divides conductive layer  60  into an array of conductive patches such as patches  72  (e.g., rectangular patches  72  as shown in  FIG. 4 ). This example is merely illustrative. In general, slots  66  may define patches of any desired dimensions and shapes (e.g., hexagonal patches such as patches  92  of  FIG. 5 , triangular patches  102  of  FIG. 6 , rounded patches such as patches  112  of  FIG. 7  or patches  122  of  FIG. 8 , etc.). In another suitable arrangement, slots  66  may form a polarizer as shown in  FIG. 9 . In general, any desired combination of patches of any different shapes, sizes, and dimensions may be used. 
     Because slots  66  and patches  72  within patterned region  62  are transparent to electromagnetic waves at the operational frequency of patch antenna resonating element  40 P, patterned region  62  may appear as an open circuit to antenna currents at the operational frequency of resonating element  40 P. This may allow the antenna current to flow to and from terminal  46  over the continuous conductive path of un-patterned region  64  without shorting to other portions of conductive layer  60 , thereby contributing to the resonance of antenna  40  and the transmission/reception of wireless signals corresponding to the antenna currents with a satisfactory antenna efficiency (e.g., similar to as if element  40 P were formed from a conductor in free space). 
     In the diagram of  FIG. 18 , slots  66  are shown as darkened lines for the sake of clarity. However, in practice, slots  66  are free of the conductive material of conductive layer  60  and may have a width that is unresolvable by (e.g., invisible to) the un-aided human eye (e.g., less than 100 microns). This may allow all of the conductive patches  72  in patterned region  62  to appear as single continuous portion of conductive material within layer  60 . Similarly, region  62  may appear as a single continuous portion of conductive material with un-patterned portion  64 . In other words, conductive layer  60  may appear to a user as a single piece of conductor (e.g., metal), even though slots  66  and a fully-functioning antenna resonating element  40 P are formed therein. Conductive layer  60  need not have a uniform thickness across its lateral area. 
     The examples of  FIGS. 11-18  are merely illustrative. If desired, combinations of inverted-F antenna structures, patch antenna structures, dipole antenna structures, monopole antenna structures, loop antenna structures, ground plane structures, or other antenna structures may be used in forming antenna  40  from conductive layer  60 . Multiple antennas  40  may be formed in a single conductive layer  60  if desired (e.g., multiple antennas  40  arranged in a phased antenna array). If desired, multiple conductive layers  60  having integrated antenna resonating elements may be formed within substrate  80  or vertically stacked with respect to each other. If desired, some portions of layer  60  may be thicker than other portions of conductive layer  60 . 
       FIG. 19  is a perspective view of electronic device  10  showing illustrative locations  220  in which antenna  40  may be mounted in device  10 . As shown in  FIG. 19 , device  10  may include housing  12 . Housing  12  may include a rear housing wall  12 R and housing sidewalls  12 E. In one suitable arrangement, a display may be mounted to front side  222  of housing  12  opposite rear housing wall  12 R. Portions of housing  12  may be formed on side  222  if desired. 
     In the example of  FIG. 19 , housing walls  12 R and  12 E are peripheral housing structures that run around the periphery of device  10 . Housing  12  may be implemented using peripheral housing structures that have a rectangular ring shape with four corresponding sidewalls  12 E (as an example). Housing sidewalls  12 E may serve as a bezel for a display on device  10  (e.g., a cosmetic trim that surrounds all four sides of the display and/or that helps hold the display to device  10 , a metal band with vertical sidewalls, curved sidewalls, etc.). 
     Peripheral housing structures  12 E and  12 R 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, or a peripheral conductive housing member (as examples). Peripheral housing structures  12 E and  12 R 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 E and  12 R. 
     Sidewalls  12 E may be substantially straight vertical sidewalls, may be curved, or may have other suitable shapes. Rear housing wall  12 R may lie in a plane that is parallel to the display on front side  222  of device  10 . In configurations for device  10  in which the rear surface of housing  12 R is formed from metal, rear housing wall  12 R may be formed from a planar metal structure and housing sidewalls  12 E may be formed as vertically extending integral metal portions of the planar metal structure. 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 . Planar rear wall  12 R may have one or more, two or more, or three or more portions. 
     Conductive layers  60  having integral antenna elements for one or more antennas  40  (e.g., as described above in connection with  FIGS. 3-18 ) may be used to form some or all of one or more sidewalls  12 E, may be used to form some or all of rear wall  12 R, and/or may be used to form a portion of the front side  222  of device  10  (e.g., conductive layer  60  may include conductive portions of housing  12 ). In these scenarios, layer  60  and antenna  40  are formed at the exterior of device  10 . For example, antenna  40  may be mounted at locations  220  at the corners of device  10 , along the edges of housing  12  such as on sidewalls  12 E, on upper or lower portions of rear housing portion  12 R, in the center of rear housing  12 R, etc. If desired, conductive layers  60  may be located within housing  12  of device  10  (e.g., conductive layer  60  may be formed from a layer of conductive traces on a substrate such as a printed circuit substrate or glass substrate within device  10 ). In another suitable arrangement, a display may be formed at side  222  of device  10 . The display may include active circuitry that emits light (e.g., liquid crystal display circuitry, light emitting diode display circuitry, etc.). The display may be covered by a display cover layer such as a glass or sapphire layer. The active circuitry may emit the light through the display cover layer. The display cover layer may cover all of side  222  (e.g., extending across a length and width of device  10 ) or may cover only some of side  222 . Conductive layer  60  may be formed from a metal coating over some or all of an interior or exterior surface of the display cover layer if desired. 
       FIG. 20  is a perspective view showing how electronic device  10  may be a laptop computer. As shown in  FIG. 20 , antenna  40  may be formed at illustrative locations such as locations  230  on device  10 . Housing  12  may include an upper housing portion  12 A and a lower housing portion  12 B. A display such as display  240  may be formed within upper housing portion  12 A whereas an input-output device such as keyboard  242  is formed in lower housing portion  12 B. Conductive housing portion  12 A may be coupled to housing portion  12 B by a hinge that configures portion  12 A to rotate with respect to portion  12 B. Some or all of the exterior surfaces of housing portions  12 A and  12 B may be formed from conductive structures such as conductive layer  60  having integral antenna components (e.g., as described above in connection with  FIGS. 3-18 ). Antenna  40  in conductive layer  60  may be formed on the same side of housing portion  12 B as keyboard  242 , on a side of portion  12 B that opposes keyboard  242  such as side  246 , on the same side of housing portion  12 A as display  240 , on a side of portion  12 A that opposes display  240  such as side  248 , or at any other desired location on the interior or exterior of device  10 . 
     The examples of  FIGS. 19 and 20  are merely illustrative and, in general, device  10  may be any desired type of electronic device having any desired form factor. If desired, device  10  may be a wearable electronic device such as a wrist watch, pendant device, or eyewear device (e.g., a virtual or augmented reality device, eyeglasses, sunglasses, etc.). For example, substrate  80  for conductive layer  60  may be formed using glass or other transparent lenses in a pair of eyeglasses or sunglasses, from a transparent crystal for a wrist watch, etc. If desired, device  10  may be integrated within a larger system or apparatus such as a vehicle, building, or electronic kiosk. For example, substrate  80  for conductive layer  60  may be formed from a glass window such as a glass window of a building, vehicle (e.g., car, airplane, boat, etc.) or electronic kiosk. 
       FIG. 21  is a graph of antenna performance (antenna efficiency) as a function of frequency for an illustrative antenna of the type shown in  FIGS. 2-18 . As shown in  FIG. 21 , curve  250  illustrates the efficiency of antenna  40  when formed in a free space environment (e.g., in scenarios where antenna  40  is not formed in conductive layer  60 ). Curve  250  may exhibit a peak antenna efficiency at an operational frequency F of antenna  40  (e.g., a radio frequency greater than or equal to 700 MHz). Curve  252  illustrates one possible efficiency of antenna  40  when formed in conductive layer  60  (e.g., as described above in connection with  FIGS. 2-18 ). Curve  252  may exhibit a peak antenna efficiency that is offset from frequency F. Matching circuitry  54  may serve to shift curve  252  in frequency back towards operational frequency F, as shown by arrow  256 . Dashed curve  258  may illustrate the efficiency of antenna  40  after compensation using matching circuitry  54 . Antenna  40  within conductive layer  60  may have a peak antenna efficiency that is offset from the peak efficiency of the free-space antenna associated with curve  250  by offset  254  (e.g., due to the influence of conductive structures such as patches  72  of  FIG. 4  in the vicinity of un-patterned region  64  of layer  60 , etc.). By selecting suitable dimensions for slots  66  and the corresponding patches within patterned region  62  (e.g., based on curve  140  of  FIG. 10 ), offset  254  may be sufficiently small (e.g., approximately zero, less than 1 dB, or less than 0.5 dB) so as to not significantly affect the successful transmission and reception of wireless data using antenna  40 . At the same time, slots  66  in region  62  may be small enough to be effectively invisible to the user of device  10 , such that un-patterned region  64  (and thus antenna  40 ) is visually indistinguishable from patterned region  62  of layer  60  and layer  60  appears to a user as a single continuous piece of metal. In scenarios where slots  66  are omitted, the resonating element of antenna  40  will be shorted to the entirety of conductive layer  60  and the antenna will exhibit a degraded efficiency as shown by curve  262 . 
     The example of  FIG. 21  is merely illustrative. In general, the efficiency curve associated with antenna  40  may have any desired shape. Antenna  40  may exhibit peaks in efficiency at more than one frequency (e.g., in scenarios where antenna  40  is a multi-band antenna). Antenna  40  may exhibit a peak efficiency at operational frequency F without the need for matching network  54  in some examples (e.g., forming antenna  40  in layer  60  may not significantly shift the resonant frequency of antenna  40 ). 
     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: 20170523
Publication Date: 20200331
Grant Date: 20200331
Priority Date: 20170523
Inventors: JIANG, YI
WU, JIANGFENG
ZHANG, LIJUN
YONG, Siwen
PASCOLINI, MATTIA
Assignee: APPLE INC
CPC Classifications: [{"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q15/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/50", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/52", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/44", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/065", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/48", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/528", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/38", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/528", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q21/065", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q15/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q21/065", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q15/0013", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q9/0421", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q7/04", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/528", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/243", "inventive": true, "first": true, "tree": "[]"}, {"code": "H01Q1/2266", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q1/528", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01Q15/0013", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 62200574