Abstract: An electronic device may have wireless circuitry with antennas. An antenna resonating element arm for an antenna may be formed from conductive housing structures running along the edges of a device. The antenna may have a pair of switchable return paths that bridge a slot between the antenna resonating element and an antenna ground. An adjustable component and a feed may be coupled in parallel across the slot. The adjustable component may switch a capacitor into use or out of use and the return paths may be selectively opened and closed to compensate for antenna loading due to the presence of external objects near the electronic device.

Abstract: An electronic device may have wireless circuitry with antennas. The electronic device may have a dielectric housing. A printed circuit board with electrical components may be mounted in the dielectric housing. Heat spreader structures may be used to dissipate heat from the electrical components. The heat spreader structures be configured to form antenna cavities. The antennas in the electronic device may be formed from the antenna cavities and may have antenna resonating elements formed on the printed circuit. An electrical component such as a light-emitting diode may be mounted in one of the antenna cavities. Each antenna element may be an inverted-F antenna resonating element with short and long arms. The short arm of each antenna resonating element may be formed from edge plated metal traces on an edge of the printed circuit.

Abstract: An electronic device may be provided with wireless circuitry. The wireless circuitry may include antennas. The antennas may include phased antenna arrays for handling millimeter wave signals. Antennas may be located in antenna signal paths. The antenna signal paths may include adjustable components such as adjustable filters, adjustable gain amplifiers, and adjustable phase shifters. Circuitry may be incorporated into an electronic device to facilitate wireless self-testing operations. Wireless self-testing may involve use of one antenna to transmit an over-the-air antenna test signal that is received by another antenna. The circuitry that facilitates the wireless self-testing operations may include couplers, adjustable switches for temporarily shorting antenna signal paths together, mixers for mixing down radio-frequency signals to allow digitization with analog-to-digital converters, and other circuitry for supporting self-testing operations.

Abstract: An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. An antenna may have an antenna feed that is coupled to a radio-frequency transceiver with a transmission line. An impedance matching circuit may be coupled to the antenna feed to match the impedance of the transmission line and the antenna. The impedance matching circuit and tunable circuitry in the antenna may be formed using integrated circuits. Each integrated circuit may include switching circuitry that is used in switching components such as inductors and capacitors into use. Sensors such as temperature sensors, current and voltage sensors, power sensors, and impedance sensors may be integrated into the integrated circuits. Each integrated circuit may store settings for the switching circuitry and may include communications and control circuitry for communicating with external circuits and processing sensor data.

Abstract: An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more dual-frequency dual-polarization patch antennas. Each patch antenna may have a patch antenna resonating element that lies in a plane and a ground that lies in a different parallel plane. The patch antenna resonating element may have a first feed located along a first central axis and a second feed located along a second central axis that is perpendicular to the first central axis. The patch antenna resonating element may be rectangular, may be oval, or may have other shapes. A shorting pin may be located at an intersecting point between the first and second axes. The patch antennas may be used in beam steering arrays. The patch antennas may be used for wireless power transfer at microwave frequencies or other frequencies and may be used to support millimeter wave communications.

Abstract: An electronic device may have wireless circuitry with antennas. An antenna resonating element arm for an antenna may be formed from peripheral conductive structures running along the edges of a device housing. The peripheral conductive structures may form housing sidewalls. A slot may be machined into a metal housing that separates the housing sidewalls from a planar rear housing portion that forms a ground for an antenna. The slot may be filled with plastic filler. A parasitic antenna resonating element arm that supports an antenna resonance at high band frequencies may be embedded within the plastic filler. The parasitic antenna resonating element may be formed from a portion of the planar rear housing portion.

Abstract: An accessory such as a wireless earbud may have an antenna for transmitting and receiving wireless signals. A housing for the earbud may have a main body portion and an extended portion that forms a stalk protruding from the main body portion. The earbud may have a speaker aligned with a speaker port in the main body portion. The antenna may have an elongated shape and may extend along the stalk. The stalk may have a plastic housing wall portion. The antenna may be formed from first and second metal traces on opposing sides of a printed circuit substrate. The first metal trace may form an antenna resonating element arm and may lie between the substrate and the plastic housing wall portion. The second metal trace may be a ground trace. A feed for the antenna may be located at a juncture between the main body portion and the stalk.

Abstract: An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include millimeter wave antenna arrays formed from arrays of patch antennas, dipole antennas or other millimeter wave antennas on millimeter wave antenna array substrates. Circuitry such as upconverter and downconverter circuitry may be mounted on the substrates. The upconverter and downconverter may be coupled to wireless communications circuitry such as a baseband processor circuit using an intermediate frequency signal path. The electronic device may have opposing front and rear faces. A display may cover the front face. A rear housing wall may cover the rear face. A metal midplate may be interposed between the display and rear housing wall. Millimeter wave antenna arrays may transmit and receive antenna signals through the rear housing wall.

Abstract: Methods and devices useful in radio frequency (RF) signal transmission are provided. By way of example, a wireless electronic device may include a transceiver, and an enclosure in which the transceiver is disposed. The enclosure may include an RF transparent layer and an RF opaque coating disposed on the RF transparent layer, where the RF opaque coating includes a pattern formed therein to enable RF signals to pass therethrough.

Abstract: An electronic device such as a wristwatch may have a housing with metal sidewalls and a dielectric rear wall. The metal sidewalls may form an antenna ground for an antenna. The antenna may include an antenna resonating element formed from conductive traces patterned directly onto an interior surface of the dielectric rear wall. The conductive traces may define a slot at the dielectric rear wall. A coil and a sensor may be mounted to the dielectric rear wall within the slot. Radio-frequency transceiver circuitry may be coupled to the conductive traces and the antenna ground and may transmit and receive radio-frequency signals through the dielectric rear wall using the antenna. Wireless power receiver circuitry may use the coil to receive wireless power signals through the dielectric rear wall. The sensor may emit and/or receive light through a transparent window in the dielectric rear wall.

Abstract: An electronic device may include a metal housing and a distributed loop antenna. The antenna may include a dielectric carrier. The antenna may include a distributed loop antenna resonating element that extends around the carrier and a loop antenna feed element on the carrier. Portions of the feed element and loop antenna resonating element may be formed from the housing. The feed element may be directly fed and may indirectly feed the distributed loop antenna resonating element via near field electromagnetic coupling. The loop antenna resonating element may include a conductive sheet on the carrier. The conductive sheet and the housing may form a conductive loop path of the loop antenna resonating element. A capacitance may be interposed in the conductive loop path and may be formed by a gap between the conductive sheet and the housing. A speaker driver may be placed within a cavity in the carrier.

Abstract: An electronic device may have a hybrid antenna that includes a slot resonating element formed from a slot in a ground plane and a planar resonating element formed over the slot. A parasitic element may be disposed over the planar element. A switch may couple the parasitic element to the ground. A tunable circuit may couple the planar element to the ground. The switch and tunable circuit may be placed in different tuning states. In a first state, the tunable circuit and switch form open circuits. In a second state, the tunable circuit may an open circuit and the switch is closed. In a third state, the tunable circuit forms a return path and the switch forms an open circuit. This may allow the antenna to operate with satisfactory efficiency in low, mid, and high bands despite volume constraints imposed on the antenna.

Abstract: An electronic device may be provided with wireless circuitry. An application processor may generate wireless data that is to be transmitted using the wireless circuitry and may process wireless data that has been received using the wireless circuitry. The wireless circuitry may include multiple baseband processors, multiple associated radios, and front-end module and antenna circuitry. Sensors may be used to provide the application processor with sensor data. During operation, the application processor and the baseband processors may be used to transmit and receive wireless communications traffic. A multiradio controller integrated circuit that does not transmit or receive the wireless communications traffic may be used in controlling the wireless circuitry based on impedance measurements, sensor data, and other information.

Abstract: An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include cellular telephone antennas, wireless local area network antennas, antenna structures for receiving satellite navigation system signals, and other antennas. An antenna may have an antenna resonating element such as an inverted-F antenna resonating element. The inverted-F antenna resonating element may have an inverted-F antenna resonating element arm formed from metal traces on a flexible printed circuit. The flexible printed circuit may be soldered to an antenna grounding clip. A screw may attach the clip, a speaker tab, a connector bracket, and other metal structures to a metal device housing that serves as ground for the antenna. The screw may be isolated from the antenna grounding clip and the other metal structures by an insulating structure such as an insulating gasket.

Abstract: An electronic device may have a display cover layer mounted to a metal housing. Electrical component layers such as a display layer, touch sensor layer, and near-field communications antenna layer may be mounted under the display cover layer. An antenna feed may have a positive feed terminal coupled to the electrical component layers and a ground feed terminal coupled to the metal housing. The electrical component layers may serve as an antenna resonating element for an antenna. The antenna may cover cellular telephone bands and may receive satellite navigation system signals. A system-in-package device may be mounted to the metal housing. A flexible printed circuit may extend between the electrical component layers and the system-in-package device. A mounting bracket for the system-in-package device may be provided with electrical isolation to enhance antenna performance in bands such as a satellite navigation system band.

Abstract: An electronic device may have wireless circuitry with antennas. An antenna resonating element arm for an antenna may be formed from conductive housing structures running along the edges of a device. The antenna may have a pair of switchable return paths that bridge a slot between the antenna resonating element and an antenna ground. An adjustable component and a feed may be coupled in parallel across the slot. The adjustable component may switch a capacitor into use or out of use and the return paths may be selectively opened and closed to compensate for antenna loading due to the presence of external objects near the electronic device.

Abstract: A consumer electronic product includes a switchable inductor array coupled to the RF antenna, the switchable inductor array comprising inductive elements and a switch circuit coupled to the inductor array to select at least one of the inductive elements and couple the selected inductive element with the RF antenna. The product can further include an assembly having a mesh that is strengthened by a stiffener. A multi-layer adhesive have a conductive layer that can be used to shield the RF antenna and adhesive layers that can provide adhesion between the stiffener and the housing of the product. The assembly can be covered by a cowling that is made of metal to provide further shielding. To reduce potential coupling between the RF antenna and the cowling, the cowling can have a portion that is formed of plastic to distance its metal portion from the antenna.

Abstract: An accessory such as a wireless headset may have an antenna for transmitting and receiving wireless signals. First and second earbuds may be coupled to different ends of a housing for the accessory. A rigid flex printed circuit board in the housing may include a rigid printed circuit portion. The rigid printed circuit portion may include first and second rigid printed circuit layers. A first portion of a flexible printed circuit may be interposed between the first and second rigid layers. A second portion of the flexible printed circuit may extend from an end of the rigid layers and may be wrapped around the first rigid layer. Planar inverted-F antenna resonating element, antenna shorting, and antenna feeding traces may be formed on the second portion of the flexible printed circuit. The efficiency of the antenna may be undisturbed by the presence of a user's body adjacent to the accessory.

Abstract: Electronic device antenna structures may include first and second antennas. A housing may have a periphery that is surrounded by peripheral conductive structures such as a segmented peripheral metal member. A segment of the peripheral metal member may be separated from a ground by an opening. An antenna feed for the first antenna may have a positive antenna terminal coupled to the peripheral metal member and a ground terminal coupled to the ground. A return path for the first antenna may span the opening in parallel with the antenna feed. A plastic carrier may be mounted to a printed circuit and a metal housing structure using screws. The plastic carrier may support an antenna resonating element for the second antenna and may support the return path for the first antenna. The screws may short metal structures on the plastic carrier to the metal structures and traces on the printed circuit.

Abstract: An electronic device may have a housing and other structures that form an antenna ground for an antenna. An antenna resonating element arm for the antenna may extend along the periphery of the housing. The resonating element arm may have opposing first and second ends. A return path may couple the resonating element arm to the antenna ground at the first end. An antenna feed may be coupled between the resonating element arm and the antenna ground in parallel with the return path. Electrical components such as first and second capacitors may be coupled between the antenna resonating element arm and the antenna ground. A first of the capacitors may be coupled between the antenna resonating element arm and the antenna ground at a location between the first and second ends. A second of the capacitors may be coupled between the second end and the antenna ground.