Antennas with split return path for an electronic device

Abstract

Electronic device (10) comprising: a housing (12) for an electronic device (10) having peripheral conductive structures (16); an antenna ground (104), the antenna ground (104) having a cutout (206) defined by a first edge and a second edge of the antenna ground (104); an antenna resonant element arm (108) formed from a segment of the peripheral conductive structures (16); a first antenna feed line (112) having a first positive feed terminal (98) coupled to the antenna resonating element arm (108) and a ground feed terminal (100) coupled to the antenna ground (104); and a split return path (110) coupled between a first point on the antenna resonating element arm (108) and a second and third point on the antenna ground, the second point being located at the first edge of the antenna ground (104) and the third point being located at the second edge of the antenna ground (104).

Description

BACKGROUNDThis relates generally to electronic devices, and more particularly to electronic devices with wireless communication circuitry.Electronic devices often include wireless communication circuitry. For example, mobile phones, computers, and other devices often include antennas and wireless transceivers for supporting wireless communication.It may be challenging to form electronic device antenna structures with desired characteristics. In some wireless devices, antennas are bulky. In other devices, antennas are compact but sensitive to the position of the antennas relative to external objects. Unless care is taken, antennas may be detuned, output wireless signals with a power less than or greater than desired, or otherwise not operate as expected.US 2015 / 0 249 292 A1 discloses an electronic device with common antenna structures which can be used both for forming a near-field communication antenna, such as a loop antenna, and a non-near-field communication antenna, such as an inverted-F antenna.It would therefore be desirable to be able to provide improved wireless circuitry for electronic devices.SUMMARYThe invention is defined in the independent claims. Advantageous embodiments are defined in the dependent claims. An electronic device may be provided with wireless circuitry and control circuitry. The wireless circuitry may include multiple antennas and transceiver circuitry. The antennas may include antenna structures at opposing first and second ends of the electronic device. The antenna structures at a given end of the device may include adjustable components that are adjusted by the control circuitry to bring the antenna structures and the electronic device into one of a number of different modes of operation or states.The antenna may include a resonant element of the mirror-inverted-F antenna formed of portions of a peripheral conductive housing structure of the electronic device, and may include an antenna ground separated from the antenna resonant element by a gap. A short circuit path may bridge the gap. An antenna feed can be connected across the gap parallel to the short circuit path.The short circuit path may be a split return path coupled between a first point on the inverted F antenna resonating element arm and second and third points on the antenna ground. The split return path may include a first inductor coupled between the first and second points and a second inductor coupled between the first and third points. The first and second inductors may be adjustable.The antenna ground may be at least partially formed by a planar conductive layer forming a rear housing wall for the electronic device. The planar conductive layer may have a cut-out region defined by first and second edges of the planar conductive layer. The second point coupled to the split return path may be on the first edge of the planar conductive layer, while the third point coupled to the split return path may be on the second edge of the planar conductive layer.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a perspective view of an illustrative electronic device according to an embodiment. FIG. 2 is a schematic diagram of illustrative circuitry in an electronic device according to an embodiment. FIG. 3 is an illustration of illustrative wireless circuitry, according to an embodiment. FIG. 4 is a schematic diagram of an illustrative inverted-F antenna according to an embodiment. FIG. 5 is a top view of an illustrative electronic device having an inverted-F antenna with a split return path, according to an embodiment. FIGS. 6 and 7 are cross-sectional views of an illustrative electronic device illustrating how inductive elements may be coupled in a shared return path of the type shown in FIG. 5 between an antenna resonating element and an antenna ground, according to an embodiment. FIG. 8 illustrates a graph of antenna performance as a function of frequency of an adjustable antenna of the type shown in FIGS. 5-7, in accordance with an embodiment of the present invention.DETAILED DESCRIPTIONElectronic devices, such as electronic device 10 in FIG. 1, may be provided with wireless communication circuitry. The wireless communication circuit may be used to support wireless communication in multiple wireless communication bands.Wireless communication circuitry may include one or more antennas. The antennas of wireless communication circuitry may include loop antennas, reverse F antennas, strip antennas, reverse F planar antennas, slot antennas, hybrid antennas including antenna structures of more than one type, or other suitable antennas. Conductive structures for the antennas may be formed of conductive structures of electronic devices, if desired.The conductive structures of electronic devices may include conductive housing structures. The package structures may include peripheral structures, such as peripheral conductive structures, that run around the periphery of an electronic device. The peripheral conductive structures may serve as a bezel for a planar structure such as a display, may serve as sidewall structures for a device package, may have portions that extend upwardly from an integral planar back side package (e.g., to form vertical planar sidewalls or curved sidewalls), and / or may form other package structures.Gaps may be formed in the peripheral conductive structures that divide the peripheral conductive structures into peripheral segments. One or more of the segments may be used in forming one or more antennas for the electronic device 10. Antennas may also be formed using an antenna baseplate and / or antenna resonating element made up of conductive housing structures (e.g., internal and / or external structures, substrate structures, etc.).The electronic device 10 may be a portable electronic device or other suitable electronic device. For example, the electronic device 10 may be a laptop computer, a tablet computer, a somewhat smaller device such as a wristwatch device, a decorative fob device, a headphone device, a hearing element device, or other wearable or miniature device, a hand-held device such as a mobile phone, a media playback device, or other small wearable device. The device 10 may also be a set-top box, a desktop computer, a display incorporating a computer or other processing circuitry, a display without an integrated computer, or other suitable electronic equipment.The device 10 may include a housing, such as a housing 12. The housing 12, which may sometimes be referred to as a "case", may be formed of plastic, glass, ceramic, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of these materials. In some situations, portions of the housing 12 may be made of dielectric or other low conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, the housing 12, or at least some of the structures from which the housing 12 is constructed, may be formed from metal members.The device 10 may include a display, such as a display 14, if desired. The display 14 may be mounted on the front of the device 10. The display 14 may be a touch-sensitive screen incorporating capacitive touch electrodes or insensitive to touch. The rear side of the housing 12 (i.e. the side of the device 10 opposite the front side of the device 10) can have a planar housing wall. The rear housing wall may include slots that pass entirely through the rear housing wall, thus separating housing wall portions (and / or side wall portions) of the housing 12 from one another. The rear housing wall may include conductive portions and / or dielectric portions. If desired, the rear housing wall may comprise a planar metal layer covered by a thin layer or with a dielectric, e.g., glass, plastic, sapphire, or ceramic. The housing 12 (e.g., the rear housing wall, the side walls, etc.) may also have shallow grooves that do not completely pass through the housing 12. The slits and grooves may be filled with plastic or other dielectric. If desired, portions of the housing 12 that have been separated from each other (e.g., by a through slot) may be connected by internal conductive structures (e.g., sheet metal or other metal pieces that bridge the slot).The display 14 may include pixels formed from light emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrowetting pixels, electrophoretic pixels, liquid crystal display (LCD) components), or other suitable pixel structures. A display cover layer, such as a clear glass or plastic layer, may cover the surface of the display 14, or the outermost layer of the display 14 may be formed of a color filter layer, a thin film transistor layer, or another display layer. Buttons, such as button 24, may protrude through openings in the top layer. The cover layer can also have further openings, such as an opening for a loudspeaker connection 26.The housing 12 may include peripheral housing structures, such as structures 16. The structures 16 may extend around the periphery of the device 10 and the display 14. In configurations in which the device 10 and the display 14 have a rectangular shape with four edges, the structures 16 may be implemented using peripheral housing structures having a rectangular ring shape with four corresponding edges (for example). The peripheral structures 16 or a portion of the peripheral structures 16 may serve as a surround for the display 14 (e.g., a cosmetic seam that surrounds all four sides of the display 14 and / or helps to retain the display 14 on the device 10). The peripheral structures 16 may also form sidewall structures for the device 10 (e.g., by forming a metal band with vertical sidewalls, curved sidewalls, etc.), if desired.The peripheral housing structures 16 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). The peripheral housing structures 16 may be formed of a metal, such as stainless steel, aluminum, or other suitable materials. One, two, or more than two separate structures may be used in forming the peripheral package structures 16.It is not necessary for the peripheral housing structures 16 to have a uniform cross section. For example, the upper portion of the peripheral housing structures 16 may include an inwardly projecting lip, if desired, which helps to hold the display 14 in place. The lower portion of the peripheral housing structures 16 may also include an enlarged lip (e.g., in the plane of the rear surface of the device 10). The peripheral housing structures 16 may have substantially straight vertical sidewalls, may have sidewalls that are curved, or may have other suitable shapes. In some configurations (e.g., when the peripheral housing structures 16 serve as a surround for the display 14), the peripheral housing structures 16 may extend around the lip of the housing 12 (i.e., the peripheral housing structures 16 may cover only the edge of the housing 12 surrounding the display 14 and not the remainder of the sidewalls of the housing 12).If desired, the housing 12 may have a conductive rear surface. For example, the housing 12 may be formed of a metal such as stainless steel or aluminum. The rear surface of the housing 12 may lie in a plane parallel to the display 14. In configurations for the device 10 in which the rear surface of the housing 12 is formed of metal, it may be desirable to form portions of the peripheral conductive housing structures 16 as integral portions of the housing structures that form the rear surface of the housing 12. For example, a housing rear wall of the device 10 may be formed from a planar metal structure, and portions of the peripheral housing structures 16 on the sides of the housing 12 may be formed as flat or curved vertically extending integral metal portions of the planar metal structure. Housing structures such as these may be machined from a metal block, if desired, and / or may include multiple pieces of metal that are assembled to form the housing 12. The planar rear wall of the housing 12 may include one or more, two or more, or three or more portions. Peripheral conductive housing structures 16 and / or the conductive back wall of the housing 12 may form one or more exterior surfaces of the device 10 (e.g., surfaces visible to a user of the device 10) and / or may be received using internal structures that do not form exterior surfaces of the device 10 (e.g., conductive housing structures that are not visible to the user of the device 10, e.g., conductive structures covered with layers such as cosmetic layers and protective layers and / or other coatings that may include dielectric materials such as glass, ceramic, plastic, or other structures or other structures that form the exterior surfaces of the device 10 and / or conceal structures 16 from view of the user).The display 14 may include a pixel array forming an active area AA that displays images for a user of the device 10. An inactive edge region IA, such as inactive region IA, may extend along one or more outer edges of the active region AA.The display 14 may have conductive structures, for example, may include an array of capacitive electrodes for a touch-sensitive sensor, conductive lines for pixel elements, drive circuitry, etc. The housing 12 may include internal conductive structures, such as metal frame members and a planar conductive housing member (sometimes referred to as a back plate) that spans the walls of the housing 12 (i.e., a substantially rectangular sheet of one or more metal parts welded or otherwise connected between opposing sides of the member 16). The backplate may form a rear exterior surface of the device 10, or may be covered with layers such as thin cosmetic layers, protective coatings, and / or other coatings that may comprise dielectric materials such as glass, ceramic, plastic, or other structures that form the exterior surfaces of the device 10 and / or serve to hide the backplate from the user's gaze. The device 10 may also include conductive structures such as circuit boards, circuit board mounted components, and other internal conductive structures. These conductive structures, which may be used to form a ground plane in device 10, may extend, for example, across active area AA of display 14.Openings may be formed in regions 22 and 20 within the conductive structures of device 10 (e.g., between peripheral conductive housing structures 16 and opposing conductive ground structures such as conductive portions of housing 12, conductive traces on a printed circuit board, conductive electrical components in display 14, etc.). These openings, sometimes referred to as gaps, may be filled with air, plastic, and other dielectrics and used in forming slot antenna resonating elements for one or more antennas in device 10.Conductive housing structures and other conductive structures in device 10 may serve as a ground plane for the antennas in device 10. The openings in regions 20 and 22 may serve as slots in open or closed slot antennas, may serve as a middle dielectric region surrounded by a conductive path of materials in a loop antenna, may serve as a space separating an antenna resonating element, such as a strip antenna resonating element or an inverted F antenna resonating element, from the ground plane, may contribute to the performance of a parasitic antenna element, or may otherwise serve as part of antenna structures formed in regions 20 and 22. If desired, the ground plane located below the active area AA of the display 14 and / or other metal structures in the device 10 may have portions that extend into portions of the ends of the device 10 (e.g., the ground may extend toward the dielectric-filled openings in the regions 20 and 22), thereby narrowing the slots in the regions 20 and 22.In general, the device 10 may include any suitable number of antennas (e.g., one or more, two or more, three or more, four or more, etc.). The antennas in the device 10 may be located at opposing first and second ends of an elongated device housing (e.g., at the ends 20 and 22 of the device 10 of FIG. 1 ), along one or more edges of a device housing, in the center of a device housing, at other suitable locations, or at one or more of these locations. The arrangement of Fig. 1 is for illustrative purposes only.Portions of the peripheral housing structures 16 may be provided with peripheral gap structures. For example, peripheral conductive housing structures 16 may include one or more gaps, such as column 18 shown in FIG. 1. The gaps in the peripheral housing structures 16 may be filled with a dielectric, such as polymer, ceramic, glass, air, other dielectric materials, or combinations of these materials. The gaps 18 may divide the peripheral housing structures 16 into one or more peripheral conductive segments. For example, there may be two peripheral conductive segments in the peripheral package structures 16 (e.g., in an array with two of the columns 18), three peripheral conductive segments (e.g., in an array with three of the columns 18), four peripheral conductive segments (e.g., in an array with four columns 18, etc.). The segments of the peripheral conductive housing structures 16 formed in this manner may form portions of antennas in the device 10.If desired, openings in the housing 12, such as grooves extending partially or fully through the housing 12, may extend across the width of the rear wall of the housing 12 and may pierce the rear wall of the housing 12 to divide the rear wall into different portions. These grooves may also extend into the peripheral housing structures 16 and may form antenna slots, gaps 18, and other structures in the device 10. A polymer or other dielectric may fill these grooves and other package openings. In some situations, housing openings forming antenna slots and other structures may be filled with a dielectric, such as air.In a typical scenario, the device 10 may include multiple antennas arranged at the top and bottom (as an example). For example, an upper antenna may be formed at the upper end of the device 10 in the region 22. For example, a lower antenna may be formed at the lower end of device 10 in region 20. The antennas may be used separately to cover identical communication bands, overlapping communication bands, or separate communication bands. The antennas may be used to implement an antenna diversity scheme or a multiple-input-multiple-output (MIMO)) antenna scheme.Antennas in device 10 may be used to support any communication bands of interest. For example, device 10 may include antenna structures for supporting local area network (GPS) communication, voice and data cellular telephone communication, global positioning system (GPS) communication), or other satellite navigation system communication, Bluetooth® communication, etc.A schematic diagram showing illustrative components that may be used in the apparatus 10 of FIG. 1 is shown in FIG. 2. As shown in FIG. 2, the apparatus 10 may include control circuitry, such as the storage and processing circuitry 28. The storage and processing circuitry 28 may include a storage device, e.g., a hard disk drive memory, non-volatile 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 the memory and processing circuitry 28 may be used to control the operation of the device 10. This processing circuit may be based on one or more microprocessors, microcontrollers (microcontrollers), digital signal processors, application specific integrated circuits (application specific integrated circuits), etc.The storage and processing circuitry 28 may be used to execute software on the device 10, such as Internet browsing applications, VOIP phone call applications (VOIP= Vo over Internet Protocol), email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, the storage and processing circuitry 28 may be used to implement communication protocols. Communication protocols that may be implemented using the storage and processing circuitry 28 include Internet protocols, wireless local area network protocols (e.g., IEEE 802.11 protocols -- sometimes referred to as WiFi® ), protocols for other short-range wireless communication links, such as the Bluetooth® protocol, mobile phone protocols, multiple-input-multiple-output (MIMO) protocols), antenna diversity protocols, etc.Input-output circuitry 30 may include input-output devices 32. The input-output devices 32 may be used to allow data to be provided to the device 10 and to allow data to be provided from the device 10 to external devices. The input-output devices 32 may include user interface devices, data port devices, and other input-output components. For example, input-output devices 32 may include touch-sensitive screens, displays without touch sensor capabilities, buttons or keys, joysticks, scroll wheels, touchpads, keypads, keyboards, microphones, cameras, buttons or keys, speakers, status indicators, light sources, audio jacks and other audio port components, digital data port devices, light sensors, position and orientation sensors (e.g., sensors such as accelerometers, gyroscopes, and compass), capacitance sensors, proximity sensors (e.g., capacitive proximity sensors, light-based proximity sensors), fingerprint sensors (e.g., a fingerprint sensor integrated into a key such as key 24 of FIG. 1, or a fingerprint sensor, The button may include the button 24 replaced), etc.The input-output circuit 30 may include wireless communication circuitry 34 for wirelessly communicating with external equipment. Wireless communication 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 wireless RF signals. Wireless signals may also be transmitted using light (e.g., using infrared communication).Wireless communication circuitry 34 may include radio frequency transceiver circuitry 90 for handling various radio frequency communication bands. For example, circuitry 34 may include transceiver circuitry 36, 38, and 42. Transceiver circuitry 36 may handle 2.4 GHz and 5 GHz bands for WiFi® (IEEE 802.11) communication and the 2.4 GHz-Bluetooth® communication band. The circuit 34 may use circuitry of a transceiver for a mobile phone 38 to handle wireless communication in frequency ranges such as a low transmission band of 700 to 960 MHz, a low-average band of 960 to 1710 MHz, an average band of 1710 to 2170 MHz, and a high band 2300 to 2700 MHz, an ultra high band of 3400 to 3700 MHz, or other transmission bands between 600 MHz and 4000 MHz, or other suitable frequencies (as examples).The circuitry 38 may handle voice data and non-voice data. If desired, wireless communication circuitry 34 may include circuitry for other short and long range wireless connections. For example, wireless communication circuitry 34 may include 60 GHz transceiver circuitry, circuitry for receiving television and radio signals, paging system transceivers, near field communication (NFC) circuitry, etc. Wireless communication circuit 34 may include global positioning system (GPS) receiver equipment, such as GPS receiver circuit 42 for receiving GPS signals at 1575 MHz or handling other satellite positioning data. In WiFi® and Bluetooth® connections and other short-range wireless connections, wireless signals are typically used to communicate data over tens or hundreds of feet. In cellular telephone and other long range connections, wireless signals are typically used to transmit data over thousands of feet or miles.Wireless communication circuitry 34 may include antennas 40. Antennas 40 may be formed using any suitable antenna types. For example, antennas 40 may include antennas having resonant elements formed of loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, inverted-F planar antenna structures, helical antenna structures, dipole antenna structures, monopole antenna structures, blends of these designs, etc. Different types of antennas may be used for different bands and combinations. For example, one type of antenna may be used in forming an antenna for a local wireless connection, and another type of antenna may be used in forming an antenna for a remote wireless connection.As shown in FIG. 3, transceiver circuitry 90 in wireless circuitry 34 may be coupled to antenna structures 40 using paths such as path 92. The wireless communication circuitry 34 may be coupled to the control circuitry 28. Control circuitry 28 may be coupled to input-output devices 32. Input-output devices 32 may provide output from device 10 and receive input from sources external to device 10.To provide antenna structures, such as the one or more antennas 40, with the capability to cover communication frequencies of interest, one or more antennas 40 may be provided with circuitry, such as filter circuits (e.g., one or more passive filters and / or one or more tunable filter circuits). Discrete components such as capacitors, inductors, and resistors may be incorporated into the filter circuits. Capacitive structures, inductive structures, and resistor structures may also be formed of patterned metal structures (e.g., a portion of an antenna). If desired, the one or more antennas 40 may be provided with adjustable circuitry, such as tunable components 102, to tune antennas via communication bands of interest. The tunable components 102 may be part of a tunable filter or tunable impedance matching network, may be part of an antenna resonating element, may span a gap between an antenna resonating element and an antenna ground, etc.The tunable components 102 may include tunable inductors, tunable capacitors, or other tunable components. Tunable components such as these may be based on switches and networks of fixed components, distributed metal structures that generate associated distributed capacitances and inductances, solid state variable devices for generating variable capacitance and inductance values, tunable filters, or other suitable tunable structures. During operation of the device 10, the control circuit 28 may transmit control signals on one or more paths, such as path 103, that adjust induction values, capacitance values, or other parameters associated with the tunable components 102, thereby tuning the antenna structures 40 to cover desired transmission bands.Path 92 may include one or more transmission lines. For example, signal path 92 of FIG. 3 may be a transmission line having a positive signal conductor, such as line 94, and a ground signal conductor, such as line 96. The lines 94 and 96 may form portions of a coaxial cable, a strip line transmission line, or a microstrip transmission line (as examples). A matching network formed of tunable components 102 such as inductors, resistors, and capacitors may be used in matching the impedance of one or more antennas 40 to the impedance of transmission line 92. The matching network components may be provided as discrete components (e.g., surface mount technology components) or from package structures, circuit board structures, traces on plastic substrates, etc. Components such as these may also be used in forming filter circuits in the antenna(s) 40, and may be tunable and / or fixed components.The transmission line 92 may be coupled to antenna feed structures associated with the antenna structures 40. For example, antenna structures 40 may form a reverse F antenna, slot antenna, a reverse F slot hybrid antenna, or other antennas having an antenna feed 112 and a positive antenna feed terminal, such as terminal 98 and an antenna ground feed terminal, such as antenna ground feed terminal 100. The positive transmission line conductor 94 may be coupled to the positive antenna feed terminal 98, and the conductor of the ground transmission line 96 may be coupled to the antenna ground feed terminal 100. Other types of antenna feed arrangements may be used if desired. For example, the antenna structures 40 may be supplied using multiple leads. The illustrative lead configuration of FIG. 3 is for illustrative purposes only.Circuit 28 may use wireless power data from a proximity sensor (see, for example, sensors 32 of FIG. 2 ), information about device orientation from an orientation sensor, information about device motion from an accelerometer or other motion sensing sensors, information about an application scenario of device 10, information whether playback is via speaker 26, information from one or more antenna impedance sensors, and / or other information that provides information about when antenna(s) 40 is affected by the presence of adjacent external objects or requires further tuning. In response, the control circuit 28 may adjust an adjustable inductor, capacitor, switch, or other tunable components 102 to ensure that the antenna 40 operates as desired. Adjustments to the components 102 may also be made to increase the range of the antenna 40 (e.g., to cover the desired transmission bands that extend over a greater frequency range than that which the antenna 40 would cover without tuning).Antennas 40 may include slot antenna structures, inverted-F antenna structures (e.g., planar and non-planar inverted-F antenna structures), loop antenna structures, combinations of these, or other antenna structures.An exemplary inverted-F antenna structure is shown in FIG. 4. As shown in FIG. 4, inverted-F antenna structure 40 (sometimes referred to herein as antenna 40 or inverted-F antenna 40) may include an inverted-F antenna resonating element, such as antenna resonating element 106, and an antenna ground (ground plane), such as antenna ground 104. Antenna resonating element 106 may have a main resonating element arm, such as arm 108. The length of the arm 108 can be selected so that the antenna 40 resonate at desired operating frequencies. For example, the length of arm 108 (or a branch of arm 108) may be one quarter of a wavelength at a desired operating frequency for antenna 40. Antenna 40 may also exhibit resonances at harmonic frequencies. If desired, slot antenna structures or other antenna structures may be incorporated into an inverted-F antenna, such as antenna 40 of FIG. 4 (e.g., to improve antenna response on one or more transmission bands). For example, a slot antenna structure may be formed between the arm 108 or other portions of the resonant element 106 and the ground 104. In these scenarios, antenna 40 may be configured as both a slot antenna and inverted-F antenna structures, and sometimes a hybrid inverted-F and slot antenna.The arm 108 may be separated from the ground 104 by a dielectric filled opening, such as a dielectric gap 101. The antenna ground 104 may be formed from housing structures such as a metal backing plate, a printed circuit board, metal portions of electronic components, or other conductive ground structures. The gap 101 may be formed of air, plastic, and other dielectric materials.The main resonating element arm 108 may be coupled to the ground 104 through a return path 110. An antenna feed 112 may include the positive antenna feed terminal 98 and the ground antenna feed terminal 100, and may be parallel to the return path 110 between the arm 108 and the ground 104. If desired, inverted-F antennas, such as illustrative antenna 40 of FIG. 4, may include more than a single resonating element arm branch (e.g., to generate multiple frequency resonances and to support operation in multiple communication bands) or may include other antenna structures (e.g., parasitic antenna resonating elements, tunable components to support antenna tuning, etc.). The arm 108 may have other shapes and, if desired, follow any desired path (e.g., paths with curved and / or straight segments).If desired, antenna 40 may include one or more adjustable circuits (e.g., tunable components 102 of FIG. 3 ) coupled to antenna resonating element structures 106, e.g., arm 108. For example, as shown in FIG. 4, tunable components 102, such as the coil 114, may be coupled between the arm structures of the antenna resonating element in the antenna 40, e.g., the arm 108 and the antenna ground 104 (e.g., the adjustable inductor 114 may bridge the gap 101). The variable inductor 114 may have an inductance value resulting in response to control signals 116 supplied to the variable inductor 114 from the control circuit 28.An upper interior view of an illustrative portion of the device 10 including antennas is shown in FIG. 5. As shown in FIG. 5, device 10 may include peripheral conductive housing structures, such as peripheral conductive housing structure 16. The peripheral conductive package structures 16 may be divided by dielectrically filled peripheral gaps (e.g., plastic gaps) 18, such as gaps 18- 1 and 18- 2. The antenna 40 may include a resonant element and a ground 104. In the example of FIG. 5, the resonating element may include an inverted-F antenna resonating element arm, e.g., arm 108, formed from a segment of peripheral conductive housing structures 16 extending between the gaps 18- 1 and 18- 2. Air and / or another dielectric may fill the slot 101 between the arm 108 and the ground structures 104. If desired, the aperture 101 may be configured to form a structure of a slot antenna resonating element that contributes to the overall performance of the antenna. Antenna ground 104 may be formed from conductive housing structures, electrical device components in device 10, printed circuit board traces, conductive traces such as wire and metal strips, or other conductive structures. In a suitable arrangement, the ground 104 includes portions formed from conductive portions of the housing 12 (e.g., portions of a housing rear wall 12 and portions of the peripheral conductive housing structures 16 separated from the arm 108 by the perimeter gaps 18- 1 and 18- 2). The antenna ground 104 may also include portions formed by portions of the display 14 (e.g., conductive portions of a display panel, a conductive plate to support the display panel, and / or a conductive frame to support the conductive plate and / or the display panel).If desired, aperture 101 may provide slot antenna resonances in one or more frequency bands for antenna 40. Antenna 40 may sometimes be referred to herein as an inverted-F antenna or a hybrid inverted-F slot antenna (for example, because slot 101 may contribute to the frequency response of antenna 40).The ground 104 may serve as an antenna ground for one or more antennas. For example, inverted-F antenna 40 may include resonant element arm 108 and ground 104, while another antenna (e.g., a wireless local area network and / or an ultra-short band antenna) may be formed from a separate resonant element in region 206 and ground 104. Inverted-F antenna 40 may be powered using an antenna feed, e.g., feed 112, with a positive feed terminal 98 coupled to peripheral conductive housing structures 16 and a ground feed terminal 100 coupled to antenna ground 104. The positive conductor of transmission line 94 and the conductor of ground transmission line 96 may form a transmission line 92 coupled between transceiver circuit 90 and antenna feed 112.The transceiver circuit 90 may include a mobile phone transceiver circuit (e.g., a wireless transceiver circuit 38 as shown in FIG. 2 ) that enables wireless communication in frequency ranges such as a low band of 700 to 960 MHz, a low-medium band of 960 to 1710 MHz, a medium band of 1710 to 2170 MHz, a high band of 2300 to 2700 MHz, and / or an ultra high band of 3400 to 3700 MHz. The transceiver circuit 90 may use the transmission line 92 and the feed line 112 to enable low-band, low-medium-band, medium-band, high-band, and / or ultra-high-band connections (e.g., radio frequency signals on a low-band, low-medium-band, high-band, and / or ultra-high-band may be transmitted to the antenna 40 via the feed line 112).If desired, an antenna, e.g., a wireless local area network and an ultra-high band antenna, may be formed within the area 206. To optimize the performance (antenna performance) of the antenna 40 and the antenna formed within the region 206, at least a portion of the ground plane 104 below the region 206 may be removed. Ground plane 104 may have any desired shape within device 10. For example, ground plane 104 may be aligned with gap 18- 1 in peripheral conductive hoses 16 (e.g., the bottom edge of gap 18- 1 may be aligned with the edge of ground plane 104 defining slot 101 adjacent gap 18- 1, such that the bottom edge of gap 18- 1 is approximately collinear with the edge of ground plane 104 at the interface between ground plane 104 and the portion of peripheral conductive structures 16 adjacent gap 18- 1). This example is illustrative only, and in another suitable arrangement, ground plane 104 may include an additional vertical slot adjacent gap 18- 1 that extends below gap 18- 1 (e.g., along the Y-axis of FIG. 5 ).If desired, ground plane 104 may include a vertical slot 162 adjacent gap 18- 2 that extends beyond the bottom edge (e.g., bottom edge 216) of gap 18- 2 (e.g., in the direction of the Y-axis of FIG. 5 ). For example, the slot 162 may have two edges defined by the ground 104 and one edge defined by the peripheral conductive structures 16. Slot 162 may have an open end defined by an open end of slot 101 at gap 18- 2. The slot 162 may have a width 172 that separates the ground 104 from the portion of the peripheral conductive structures 16 below the slot 18- 2 (e.g., in the direction of the X-axis of FIG. 5 ). Because the portion of the peripheral conductive structures 16 under the gap 18- 2 is shorted to the ground 104 (and thus forms part of the antenna ground for the antenna structures 40), the slot 162 can effectively form an open slot with three sides defined by the antenna floor for the antenna structures 40. The slot 162 may have any desired width (e.g., about 2 millimeters, less than 4 millimeters, less than 3 millimeters, less than 2 millimeters, less than 1 millimeter, more than 0.5 millimeters, more than 1.5 millimeters, more than 2.5 millimeters, 1-3 millimeters, etc.). The slot 162 may have an elongated length 178 (e.g., perpendicular to the width 172). The slot 162 may have any desired length (e.g., 10-15 millimeters, greater than 5 millimeters, greater than 10 millimeters, greater than 15 millimeters, greater than 30 millimeters, less than 30 mm, less than 20 millimeters, less than 15 millimeters, less than 10 millimeters, between 5 and 20 millimeters, etc.). The electronic device 10 may be characterized by the longitudinal axis 282. The length 178 may extend parallel to the longitudinal axis 282 (and the Y axis). If desired, portions of the slot 162 in one or more frequency bands may provide slot resonances for the antenna 40. The length and width of the arm 162 may be selected such that the antenna 40 resonate at desired operating frequencies. If desired, the overall length of arm 101 and arm 162 may be selected such that antenna 40 resonate at desired operating frequencies.The adjustable component 114 may bridge the slot 101 at a first location along the slot 101 (e.g., the component 114 may be coupled between the terminal 126 on the ground plate 104 and the terminal 128 on the peripheral conductive structures 16). The component 114 may include switches coupled to fixed components, for example inductors for providing adjustable amounts of inductance or an open circuit between the ground 104 and the peripheral conductive structures 16. the component 114 may also include fixed components not coupled to switches or a combination of components coupled to switches and components not coupled to switches. These examples are for illustrative purposes only, and generally, component 114 may include other components, for example, adjustable return path switches, switches coupled to capacitors, or other desired components. The adjustable component 114 may include one or more inductors coupled to a radio frequency switching circuit. In an illustrative example, the adjustable component 114 may include two inductors connected in parallel between the terminals 126 and 128. A radio frequency switching circuit may selectively couple the inductors between terminals 126 and 128 to fine tune the antenna. Additional adjustable components may be included at any desired location within the electronic device 10 (i.e., between the resonating element arm 108 and the mass 104, between different portions of the element 108, the gap 18- 1, or the gap 18- 2, etc.).The resonance of the antenna 40 within the low band LB (e.g., 700 MHz to 960 MHz or in another suitable frequency range) may be associated with the distance along the peripheral conductive structures 16 between the feed line 112 and the gap 18- 2, for example. FIG. 5 is a front view of the appliance 10 such that the gap 18- 2 of FIG. 5 lies on the right edge of the appliance 10 when the appliance 10 is viewed from the front (e.g., the side of the appliance 10 on which the display 14 is formed), and the gap lies on the left edge of the appliance 10 when the appliance 10 is viewed from the rear. Tunable components, such as component 114, may be used to tune the frequency response of antenna 40 in low band LB. The resonance of antenna 40 in mid-band MB (e.g., 1710 MHz to 2170 MHz) may be associated with the distance along peripheral conductive structures 16 between lead 112 and gap 18- 1, for example. If desired, tunable components such as component 114 may be used to tune the response of antenna 40 in medium band MB. Antenna performance in high band HB (e.g., 2300 MHz to 2700 MHz) may be supported by slot 162 in ground plane 104 and / or by a harmonic mode of resonance associated with arm 108. If desired, tunable components such as component 114 may be used to tune the response of antenna 40 in high band HB.The antenna structures 40 may include a return path, for example the return path 110, coupled between the arm 108 (at the terminal 202) and the ground 104 (at the terminals 204- 1 and 204- 2). Return path 110 may include one or more inductors, for example, inductors 212 and 214. If desired, the inductors 212 and 214 may be coupled in parallel between the terminal 202 on the peripheral conductive housing structure 16 and at various locations of the ground 104. For example, the inductor 212 may be coupled between the terminal 202 and the ground terminal 204- 1, while the inductor 214 is coupled between the terminal 202 and the ground terminal 204- 2. The inductor 212 may therefore form a first conductive path (branch) of the shared return path 110 between the terminal 202 and the terminal 204- 1, while the inductor 214 forms a second conductive path (branch) of the shared return path 110 between the terminal 202 and the terminal 204- 2. The inductors 212 and 214 may be fixed inductors or adjustable inductors.For example, each inductor may be coupled to a switch that selectively opens to disconnect the inductor between terminal 202 and ground 104. The inductors 212 and 214 may be adjusted (e.g., corresponding switches may be opened or closed) to tune the resonance of the antenna structures 40 in low band, mid band, high band, and / or other bands.In this manner, return path 110 may be shared between a single point 202 on peripheral conductive housing structures 16 and multiple points on ground 104. Since return path 110 is split between two branches coupled in parallel between terminal 202 and ground 104, return path 110 may sometimes be referred to herein as a split short path or a split return path. For example, the shared short path may improve antenna efficiency for the non-near field communication antenna formed of structures 40 relative to scenarios where the return path is implemented using a single conductive path between terminal 202 and ground 104.The terminals 202, 204- 1, and 204- 2 may include any conductive structures. For example, the terminal 202 may include a conductive screw secured to peripheral conductive housing structures 16. The terminal 204- 1 may include a conductive screw secured to a portion of the ground 104, e.g., a conductive layer of the housing 12 (e.g., a housing rear wall 12). If desired, at the terminal 204- 1, another conductive structure, such as a spring or a pin, that electrically connects the conductive backing plate to a conductive portion of the display 14 (e.g., a grounded portion of the display 14 that forms part of the ground 104 for the antenna 40). The terminal 204- 2 may have the same structure as the terminal 204- 1 or may have a different structure than the terminal 204- 1. The position of the terminals 204- 1 and 204- 2 may be adjusted to reduce antenna performance and frequency response of the antenna 40 (e.g., to tune the antenna 40 to resonate at desired frequencies). The clamps 204- 1 and 204- 2 may be separated from each other by any desired distance (e.g., between 2 and 15 millimeters, between 8 and 20 millimeters, between 5 and 15 millimeters, between 10 and 25 millimeters, between 5 and 30 millimeters, more than 2 millimeters, more than 5 millimeters, more than 8 millimeters, more than 10 millimeters, more than 15 millimeters, less than 10 millimeters, less than 15 millimeters, less than 20 millimeters, less than 30 millimeters, etc.).As discussed above, a portion of the ground plane 104 adjacent to the gap 18- 1 may be removed (e.g., to improve the performance of the wireless local area network and the ultra-high band antenna in the area 206). The removed portion of the ground plate 104 is sometimes referred to as a cut-out. The cutout may have a width 247. The width 247 may be between 2 and 15 millimeters, between 8 and 12 millimeters, between 5 and 15 millimeters, between 10 and 20 millimeters, between 5 and 30 millimeters, greater than 2 millimeters, greater than 5 millimeters, greater than 8 millimeters, greater than 10 millimeters, greater than 15 millimeters, less than 10 millimeters, less than 15 millimeters, less than 20 millimeters, less than 30 millimeters, or any other desired distance. The distance 247 may be adjusted to improve antenna performance and ensure that the antenna oscillates in the desired frequency bands. In embodiments where antenna ground 104 includes multiple layers (e.g., both a conductive layer of housing 12 and a conductive portion of display 14), the cutout may be formed only in a subset of the layers. For example, the cutout may be provided only in the conductive layer of the housing 12 and not in the conductive portion of the display 14.If desired, inductors 214 and 212 may be formed on one or more substrates, such as one or more flexible circuit boards. FIG. 6 is a cross-sectional view of the electronic device 10 (e.g., in the direction of arrow 284 in FIG. 5 ) showing how the inductor 214 may be formed on a flexible printed circuit. As shown in FIG. 6, the display 14 for the electronic device 10 may include a display cover layer, such as the display cover layer 302, covering the display panel 304. The display panel 304 (sometimes referred to as a display module) may be any desired type of display panel and may include pixels formed from light emitting diodes (LEDs), organic LEDs (OLEDs), plasma cells, electrophoretic pixels, liquid crystal displays (LCDs), components, or other suitable pixel structures. For example, the lateral area of the display panel 304 may determine the size of the active area AA of the display 14 (FIG. 1 ). The display panel 304 may include active light emitting components, touch sensitive components (e.g., touch sensor electrodes), pressure sensor components, and / or other active components. The display cover layer 302 may be a layer of clear glass, plastic, or other dielectric that covers the light emitting surface of the underlying display panel. In another suitable arrangement, the display cover layer 302 may be the outer layer of the display panel 304 (e.g., the layer 302 may be a color filter layer, thin film transistor layer, or other display layer). Buttons may pass through the openings in the cover layer 302 (see button 24 in FIG. 1 ). The cover layer can also have further openings, such as an opening for a loudspeaker connection 26 (see loudspeaker connection in FIG. 1 ).The display panel 304 may be supported in the electronic device 10 by a conductive display support plate (sometimes referred to as an intermediate plate or a display plate) such as the display plate 306. The conductive display frame 308 may hold the display panel 306 and / or the display panel 304 in place within the housing 12. For example, the display frame 308 may be annular and include a portion that extends around the perimeter of the display panel 304 and encloses a central opening. The display panel 306 and the display frame 308 may both be made of conductive material (e.g., metal). The display panel 306 and the display frame 308 may be in direct contact such that the display panel 306 and the display frame 308 are electrically connected. If desired, the display plate 306 and the display frame 308 may be integrally formed (e.g., from the same piece of metal).A plastic frame 310 may be molded around the display frame 308. The plastic frame 310 may also be annular (similar to the display frame 308). The electronic device 10 may have a rectangular perimeter with top and bottom edges connected together by left and right edges. The plastic frame 310 may surround the rectangular perimeter of the electronic device 10. The plastic frame 310 may be formed of molded plastic or other desired dielectric material and serve to mount the frame 308, and thus the plate 306 and the plate 304, to peripheral conductive housing structures 16. Conductive frame 308, conductive plate 306, and conductive plate portions 304 (e.g., conductive electrodes, pixel circuits, ground layers, ferrite layers, shield layers, etc.) may form a portion of antenna ground 104 for antenna 40 (FIG. 5 ).As shown in FIG. 6, a conductive portion of the housing 12, such as a conductive housing layer 320 (e.g., a conductive device backplate 10 extending between the left and right edges of the device 10 and forming a portion of the antenna ground 104) may be separated from the portion of the peripheral housing structures 16 forming the arm of the antenna resonating element 108 by the cutout 206. Additional electronic components may be formed in region 206. The desired components may be mounted within the region 206. In the example of FIG. 6, a printed circuit 322 and an electronic component 312 are mounted in area 206.The printed circuit 322 may be a rigid printed circuit board (e.g., a printed circuit board made of fiberglass-filled epoxy or other rigid circuit board material) or a flexible printed circuit board (e.g., a flexible printed circuit board made of a polyimide layer or other flexible polymer layer). The printed circuit board 322 may include antenna traces such as an antenna resonating element (e.g., for a wireless local area network and an ultra-high band antenna), surface mounted technology components, terminals for an antenna feed, or other desired traces or components. The electronic component 312 may be any desired type of component. In some embodiments, component 312 may be an input / output component or form portions of an input / output component (e.g., input / output devices 32 in FIG. 2 ), such as a button, a camera, a speaker, a light sensor, a position and orientation sensor (e.g., an accelerometer, a gyroscope, a compass, etc.), a capacitive sensor, a proximity sensor (e.g., a capacitive proximity sensor, a light-based proximity sensor, etc.), a fingerprint sensor, etc. In a suitable arrangement, electronic component 312 may be an audio receiver (e.g., an ear speaker). Electronic component 312 may be made of plastic or other dielectrics, if desired, to minimize interference with the adjacent antennas (e.g., antenna 40 and / or an antenna formed on printed circuit 322).The example of FIG. 6 in which the printed circuit 322 and the electronic component 312 are formed in the region 206 is merely illustrative. If desired, additional components may be formed in region 206. In general, any number of components of a desired type may be included in the region 206.The flexible circuit 322 and the electronic component 312 may be formed over a cutout in the conductive support plate 320. The package 12 may include dielectric package portions such as the dielectric layer 324 and conductive package portions such as the conductive layer 320 (sometimes referred to herein as a conductive package wall 320). If desired, the dielectric layer 324 may be formed under the layer 320 such that the layer 324 forms an outer surface of the device 10 (and, for example, protects the layer 320 from wear and / or prevents the layer 320 from being viewed by the user). The conductive housing portion 320 may form part of the ground 104. For example, the conductive housing portion 320 may be a conductive support plate or wall (e.g., a conductive back wall or rear housing wall) for the device 10. If desired, the conductive housing portion 320 may extend across the width of the device 10 (e.g., between two opposing sidewalls formed by peripheral housing structures 16). If desired, the conductive housing portion 320 and the opposing sidewalls of the device 10 may be made from a single piece of metal, or the portion 320 may be otherwise shorted to the opposing sidewalls of the device 10. The dielectric layer 324 may be, for example, a thin glass, sapphire, ceramic or sapphire layer or other dielectric coating. In another suitable arrangement, conductive layer 324 may be omitted, if desired.The adjustable component 214 may include at least one inductor coupled to a corresponding switch. The switch may be controlled to selectively connect the inductor between terminals 202 and 204- 2 (as shown in FIG. 5 ). The adjustable component 214 may be embedded (e.g., as a distributed inductance) in the flexible printed circuit 314. This example is illustrative only. If desired, the adjustable component 214 may be formed from components mounted on the surface of the flexible printed circuit 314 (e.g., surface mount technology components). The flexible printed circuit 314 may be formed from a polyimide layer or other flexible polymer layer. The flexible printed circuit 314 may have a longitudinal axis that extends parallel to the Y axis (e.g., the flexible printed circuit 314 extends into and out of the page of FIG. 6 ). In other words, the lateral surface of the flexible printed circuit 314 may lie in the Y-Z plane of FIG. 6.The flexible printed circuit 314 may be attached to peripheral housing structures 16 or other internal structures using any fasteners. For example, one or more optional screws, such as screws 316 and 318, may be included to secure the flexible printed circuit 314 to the housing structures 16. The flexible printed circuit 314 may include one or more apertures to receive fasteners such as screws. The flexible printed circuit 314 may be mechanically attached to the peripheral conductive housing structure 16 or other desired structure in the electronic device 10.The peripheral conductive housing structure 16 may include integral protrusions 326. The integral protrusions 326 may extend away from the peripheral conductive housing structure 16 toward the interior of the electronic device 10. If desired, integral protrusions 326 may be used to mount various components in electronic device 10. For example, in one illustrative embodiment, the flexible printed circuit 314 may be attached to a protrusion of the peripheral conductive package structure 16. In another example, the plastic frame 310 may be supported by a protrusion 326 of the peripheral conductive housing structure 16.Although not explicitly shown in FIG. 6, the flexible printed circuit 314 may be electrically connected to peripheral conductive housing structures 16 (i.e., at the terminal 202 in FIG. 5 ). The flexible printed circuit 314 may be electrically connected to peripheral conductive housing structures 16 on the terminal 202 with a screw or other desired element (e.g., a clip, bracket, spring, pin, etc.). Although not explicitly shown in FIG. 6, the flexible printed circuit 314 may be electrically connected to the conductive backing plate 320 (e.g., at the terminal 204- 2 in FIG. 5 ). The flexible printed circuit 314 may be electrically connected to the conductive support plate 320 at the terminal 204- 2 with a screw or other desired element (e.g., a clip, clip, spring, pin, etc.).FIG. 7 is a cross-sectional view of the electronic device 10 (e.g., taken in the direction of arrow 286 in FIG. 5 ) showing how the inductor 212 may be formed on a flexible printed circuit. As shown in FIG. 7, the adjustable inductor 212 may include an inductor 340 coupled to a switch 342. Switch 342 may be selectively opened and closed (e.g., with control signals provided by control circuit 28 of FIG. 2 ). When the switch 342 is closed, the inductor 340 may be connected between the terminals 202 and 204- 1 (as shown in FIG. 5 ). The inductor 340 and the switch 342 may be mounted on the flexible printed circuit 330. The flexible printed circuit 330 may be made of a polyimide film or other flexible polymer layer. In the embodiment of FIG. 7, the inductor 340 is shown mounted on the surface of the flexible printed circuit 330 (e.g., the inductor 340 may be a surface mounted technology component). This example is illustrative only, and the inductor 340 may be embedded in the flexible printed circuit 330.The flexible printed circuit 330 may be attached to surrounding housing structures or internal structures using any fasteners. For example, the flexible printed circuit 330 may be fastened to a protrusion 326 of the peripheral conductive housing structure 16 with the screw 332 (sometimes referred to as a fastener). The flexible printed circuit 330 may include an opening, such as a threaded hole, to receive the screw 332. The screw 332 may also electrically connect the flexible printed circuit 330 to the peripheral conductive housing structure 16 (e.g., terminal 202 on the protrusion 326). This example is illustrative only, and the terminal 202 may be generally anywhere on the peripheral conductive housing structure 16. The flexible printed circuit 330 may be attached to the peripheral conductive housing structure 16 or other desired structure in the electronic device 10.As shown in FIG. 7, the flexible printed circuit 330 may be attached to the conductive support plate 320 using various fasteners. In FIG. 7, a screw mandrel 334 may be formed on the conductive backing plate 320. The screw 336 may be received by the screw mandrel 334, securing the flexible printed circuit 330 to the conductive housing wall 320. The flexible printed circuit 330 may include an opening that receives the screw 336 and / or the mandrel 334. One or two screw studs 334 and the screw 336 may be made of a conductive material (e.g., metal) such that the flexible printed circuit 330 is electrically connected to the conductive backing plate 320 (e.g., the screw stud 334 and / or the screw 336 form the terminal 204- 1 in FIG. 5 ). In some embodiments, the screw mandrel 334 may be absent or may be integrally formed with the conductive backing plate 320.To optimize antenna performance of antenna 40, conductive layer 320 at terminal 204- 1 may be shorted to conductive portions of display 14. If desired, an additional conductive structure such as a spring 338 may be coupled between the screw 336 and the display plate 306. The spring 338 may electrically connect different components of the device ground (e.g., ground 104 in FIG. 5 ) such that the conductive structures disposed closest to the resonating element arm 108 are maintained at ground potential and form a portion of the antenna ground 104. The display plate 306 and the conductive support plate 320 may form both portions of the ground 104 in this example. The spring 338 (or other desired conductive element) may electrically connect the conductive support plate 320 to the display plate 306. The display plate 306 may include one or more grooves to receive a portion of the conductive structure 338. The spring 338 may help establish a reliable electrical connection between the conductive housing structure 320 and the display plate 306. The example of a spring electrically connecting the conductive housing structure 320 and the display plate 306 is merely illustrative, and other conductive structures such as a bracket, a clip, a spring, a pin, a screw, a solder, a weld, a conductive adhesive, a wire, a metal strip, or a combination thereof may be used to electrically connect the conductive housing structure 320 to the display plate 306.The flexible printed circuit 330 may include bends and bends 352 and 354 that allow different portions of the flexible printed circuit 330 to be disposed in different planes. A first portion of the flexible printed circuit 330 between the screw 332 and the bend 352 may extend along a longitudinal axis that is parallel to the X axis (e.g., the first portion of the flexible printed circuit 330 may be disposed in the XY plane). A second portion of the flexible printed circuit 330 between the bend 352 and the bend 354 may extend along a longitudinal axis that is parallel to the Z axis (i.e., the second portion of the flexible printed circuit 330 may be disposed in the YZ plane). A third portion of the flexible printed circuit 330 between the bend 354 and the screw 336 may extend along a longitudinal axis that is parallel to the X axis (i.e., the third portion of the flexible printed circuit 330 may be disposed in the XY plane). The bends in the flexible printed circuit 330 may serve to couple the flexible printed circuit between the protrusion in the peripheral conductive structure and the conductive backing plate at the device back side (e.g., by receiving other components such as component 312).In some of the aforementioned embodiments, fasteners used to couple conductive components to antenna ground are described. It should be appreciated that any fastening means, e.g., a clip, clip, spring, pin, screw, solder, weld, conductive adhesive, or a combination thereof, may be used. Fasteners may be used to electrically connect and / or mechanically fix components in the electronic device 10. Fasteners may be used on any terminals within the electronic device 10 (e.g., terminals 202, 204- 1, and 204- 2).Additionally, at each ground terminal in the device (e.g., terminals 204- 1 and 204- 2), various components of the device ground (e.g., ground 104 in FIG. 5 ), such as conductive housing structure 320 and display plate 306, may be electrically connected such that the conductive structures located proximate to resonating element arm 108 are maintained at a ground potential and form a portion of antenna ground 104. It should be appreciated that the conductive structures closest to the resonating element arm 108, e.g., the conductive portions of the display 14, may serve to optimize antenna performance of the antenna 40, for example.FIG. 8 is a graph of antenna power versus frequency for an illustrative antenna of the type shown in FIGS. 5-7. As shown in FIG. 8, the antenna 40 may have resonances in the middle band MB. The middle band MB may extend from 1710 MHz to 2170 MHz or over another suitable frequency range. As shown in FIG. 8, the antenna 40 may have antenna performance characterized by the curve 402 in the medium band MBwhen only the adjustable inductor 212 is present (e.g., when no divided return path is used and the adjustable inductor 212 forms the return path 110 without the adjustable inductor 214). The antenna 40 may have antenna performance characterized by the curve 404 in the mid-band MBwhen only the adjustable inductor 214 is present (e.g., when no split return path is used and the adjustable inductor 214 forms the return path 110 without the adjustable inductor 212). When a split return path is used (e.g., as shown in FIGS. 5-7 ), the antenna 40 may have antenna performance characterized by curve 406 in the mid-band MB. Curve 406 may include contributions from both inductors 214 and 212 and extend coverage of antenna 40 beyond the entire center band MB. This example is illustrative only. If desired, antenna 40 may produce resonances in a subset of these bands and / or in additional bands.In accordance with one embodiment of the invention, an electronic device is described that includes an electronic device having peripheral conductive structures, an antenna ground, an antenna resonating element arm formed from a segment of the circumferential conductive structures, an antenna feed having a positive feed terminal coupled to an antenna resonating element arm, and a ground feed terminal coupled to an antenna ground, a shared return path coupled between a first point on the antenna resonating element arm and second and third points on the antenna ground.According to another embodiment, the split return path includes a first inductor coupled between the first and second points.According to another embodiment, the split return path includes a second inductor coupled between the first and third points.In accordance with another embodiment, the first inductor is adjustable.In accordance with another embodiment, the second inductor is adjustable.According to another embodiment, the antenna ground comprises a cutout defined by a first and a second edge of the antenna ground.In accordance with another embodiment, the second point is at the first edge of the antenna ground and the third point is at the second edge of the antenna ground.According to a further embodiment, the electronic device comprises an electronic component located in this cutout.According to another embodiment, the segment of the peripheral conductive structures is a first segment of the peripheral conductive structures, and the antenna ground includes a conductive housing back wall extending between second and third segments of the peripheral conductive structures.According to another embodiment, the first inductor is formed on a flexible printed circuit board coupled between the first point on the antenna resonating element arm and the second point on the antenna ground, wherein the antenna ground comprises a conductive display plate and the electronic device comprises a conductive fastener electrically connecting the flexible printed circuit board to the conductive housing rear wall at the second point and a conductive structure electrically connecting the conductive housing rear wall to the conductive display plate at the second point.In accordance with one embodiment of the invention, an electronic device is described comprising a housing having peripheral conductive structures and a planar conductive layer extending between first and second segments of the peripheral conductive structures, a first dielectric-filled gap in the peripheral conductive structures separating the first segment from a third segment of the peripheral conductive structures, a second dielectric-filled gap in the peripheral conductive structures separating the second segment from the third segment, an antenna resonating element formed from at least the third segment of the peripheral conductive structures, an antenna ground comprised of at least one planar conductive layer and the first and second segments of the peripheral conductive structures, and an antenna return path coupled between a first terminal on the antenna resonating element and second and third terminals on the antenna ground.According to another embodiment, the planar conductive layer includes a cutout defined by first and second edges of the planar conductive layer.In accordance with another embodiment, the second terminal is at the first edge of the planar conductive layer and the third terminal is at the second edge of the planar conductive layer.In accordance with another embodiment, the cutout is proximate the first dielectric-filled gap.In accordance with another embodiment, the planar conductive layer includes a vertical slot extending over an edge of the second dielectric-filled gap, the vertical slot having edges defined by the planar conductive layer and the second segment of the peripheral conductive structures.In accordance with another embodiment, the antenna return path includes a first adjustable inductor coupled between the first terminal and the second terminal and a second adjustable inductor coupled between the first terminal and the third terminal.According to another embodiment, the electronic device includes a display, wherein the antenna ground includes conductive portions of the display.In accordance with one embodiment, an antenna is provided that includes: an inverted-F antenna resonating element arm; an antenna feed having a positive antenna feed terminal coupled to an inverted-F antenna resonating element arm; an antenna ground feed terminal coupled to the antenna ground; a first inductor coupled between a first terminal on the inverted-F antenna resonating element arm and a second terminal on the antenna ground; a second inductor coupled between the first terminal on the inverted-F antenna resonating element arm and a third terminal on the antenna ground that is different than the second terminal.In accordance with another embodiment, the first inductor is adjustable.In accordance with another embodiment, the second inductor is adjustable.

Claims

An electronic device (10) comprising: a housing (12) for an electronic device (10) having peripheral conductive structures (16); an antenna ground (104), the antenna ground (104) having a cutout (206) defined by a first edge and a second edge of the antenna ground (104); an antenna resonating element arm (108) formed from a segment of the peripheral conductive structures (16); a first antenna feed line (112) having a first positive feed terminal (98) coupled to the antenna resonating element arm (108), and a ground feed terminal (100) coupled to the antenna ground (104); a split return path (110) coupled between a first point on the antenna resonating element arm (108) and second and third points on the antenna ground, the second point being located on the first edge of the antenna ground (104) and the third point being located on the second edge of the antenna ground (104).The electronic device (10) of claim 1, wherein the shared return path (110) comprises a first adjustable inductor (212) coupled between the first point and the second point.The electronic device (10) of claim 2, wherein the shared return path (110) comprises a second adjustable inductor (214) coupled between the first point and the third point.The electronic device (10) of claim 1, wherein the segment of the peripheral conductive structures (16) is a first segment of the peripheral conductive structures (16) and the antenna ground (104) comprises a conductive housing back wall (320) extending between second and third segments of the peripheral conductive structures (16).The electronic device (10) of claim 4, wherein the first inductor (212) is formed on a flexible printed circuit board coupled between the first point on the antenna resonating element arm (108) and the second point on the antenna ground (104), the antenna ground (104) further comprising a conductive display plate (306), and the electronic device (10) further comprising: a conductive fastener (334, 336) electrically connecting the flexible printed circuit board to the conductive housing back wall (320) at the second point; and a conductive structure (338) electrically connecting the conductive housing back wall (320) to the conductive display plate (306) at the second point.An electronic device (10) comprising: a housing (12) having peripheral conductive structures (16) and a planar conductive layer (320) extending between first and second segments of the peripheral conductive structures (16); a first dielectric-filled gap (18-1) in the peripheral conductive structures (16) separating the first segment from a third segment of the peripheral conductive structures (16); a second dielectric-filled gap (18-2) in the peripheral conductive structures (16) separating the second segment from the third segment; an antenna resonating element (108) formed from at least the third segment of the peripheral conductive structures (16); an antenna ground (104) formed at least from the planar conductive layer (320) and the first and second segments of the peripheral conductive structures (16), the planar conductive layer (320) having a cutout (206) defined by a first edge and a second edge of the planar conductive layer (320); and an antenna return path (110) coupled between a first terminal (202) on the antenna resonating element (108) and second (204-1) and third (204-2) terminals on the antenna ground (104), the second terminal (204-1) being disposed on the first edge of the conductive layer (320) and the third terminal (204-2) being disposed on the second edge of the planar conductive layer (320).The electronic device (10) of claim 6, wherein the cutout (206) is proximate the first dielectrically filled gap (18-1).The electronic device (10) of claim 7, wherein the planar conductive layer (320) has a vertical slot (162) extending beyond an edge (216) of the second dielectric filled gap (18-2), and the vertical slot (162) has edges defined by the planar conductive layer (320) and the second segment of the peripheral conductive structures (16).The electronic device (10) of claim 7, wherein the antenna return path (110) comprises a first adjustable inductor (214) coupled between the first terminal (202) and the second terminal (204-1), and a second adjustable inductor (212) coupled between the first terminal (202) and the third terminal (204-2).The electronic device (10) of claim 6, further comprising: a display (14), wherein the antenna ground (104) comprises conductive portions of the display (14).An antenna (40) comprising: an antenna ground (104) having a cutout (206) defined by a first edge and a second edge of the antenna ground (104); an inverted F antenna resonating element arm (108); an antenna feed having a positive antenna feed terminal (98) coupled to the inverted F antenna resonating element arm (108), and an antenna ground feed terminal (100) coupled to the antenna ground (104); a first inductor (212) coupled between a first terminal (202) on the inverted F antenna resonating element arm (108) and a second terminal (204-1) on the antenna ground (104); and a second inductor (214) coupled between the first terminal (202) on the inverted F antenna resonating element arm (108) and a third terminal (204-2) on the antenna ground (104) different from the second terminal (204-1), wherein the second terminal (204-1) is disposed on the first edge of the antenna ground (104) and the third terminal (204-2) is disposed on the second edge of the antenna ground (104).The antenna (40) of claim 11, wherein the first (212) and second inductors (214) are adjustable.

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