Abstract: An electronic device may be provided with wireless circuitry. Control circuitry may be used to adjust the wireless circuitry. The wireless circuitry may include an antenna that is tuned using tunable components. The control circuitry may gather information on the current operating mode of the. electronic device, sensor data from a proximity sensor, accelerometer, microphone, and other sensors, antenna impedance information for the antenna, and information on the use of connectors in the electronic device. Based on this gathered data, the control circuitry can adjust the tunable components to compensate for antenna detuning due to loading from nearby external objects, may adjust transmit power levels, and may make other wireless circuit adjustments.

Abstract: An electronic device may be provided with antenna structures. The antenna structures may be coupled to non-near-field communications circuitry such as cellular telephone transceiver circuitry or wireless local area network circuitry. When operated at non-near-field communication frequencies, the antenna structures may be configured to serve as one or more inverted-F antennas or other antennas for supporting far field wireless communications. Proximity sensor circuitry and near-field communications circuitry may also be coupled to the antenna structures. When operated at proximity sensor frequencies, the antenna structures may be used in forming capacitive proximity sensor electrode structures. When operated at near-field communications frequencies, the antenna structures may be used in forming an inductive near-field communications loop antenna.

Abstract: Antenna structures for an antenna may be formed from a dielectric carrier with metal structures. The metal structures may be patterned to cover all sides of the dielectric carrier. The dielectric carrier may have a shape with six sides or other shape that creates a three-dimensional layout for the antenna structures. The antenna structures may have a tunable circuit that allows the antenna to be tuned. The tunable circuit may have first and second terminals coupled to one of the sides of the carrier. The metal structures may be configured to form an inverted-F antenna resonating element. Portions of the metal structures may form a first arm for an inverted-F antenna and portions of the metal structures may form a second arm for the inverted-F antenna. The antenna may operate in multiple communications bands. The tunable circuit may tune one band without significantly tuning other bands.

Abstract: An electronic device may have a conductive housing with an antenna window. A display cover layer may be mounted on the front face of the device. Antenna and proximity sensor structures may include a dielectric support structure with a notch. The antenna window may have a protruding portion that extends into the notch between the display cover layer and the antenna and proximity sensor structures. The antenna and proximity sensor structures may have an antenna feed that is coupled to a first conductive layer by a high pass circuit and capacitive proximity sensor circuitry that is coupled to the first conductive layer and a parallel second conductive layer by a low pass circuit. The first conductive layer may be formed from a metal coating on the support structure. The second conductive layer may be formed from patterned metal traces in a flexible printed circuit.

Abstract: An electronic device may have an antenna for providing coverage in wireless communications bands of interest such as a low frequency communications band, a middle frequency communications band, and a high frequency communications band. Slot structures in the antenna that might reduce efficiency in the high frequency communications band may be avoided by capacitively loading the antenna and omitting meandering paths in the antenna. A capacitor may be coupled between an antenna ground formed from a metal housing structure and an antenna resonating element having a curved shape that conforms to the shape of the edge of the electronic device. The capacitor may have interdigitated fingers and may be adjustable to tune the antenna. The antenna may transmit and receive radio-frequency signals through a display cover layer in a display and a dielectric antenna window portion of the housing.

Abstract: An electronic device may have a conductive housing with an antenna window. Antenna structures may be mounted adjacent to the antenna window. The antenna structures may have a dielectric carrier. Patterned metal antenna traces may be formed on the surface of the dielectric carrier. A proximity sensor may be formed from a flexible printed circuit mounted on the dielectric carrier. The flexible printed circuit may have a tail that contains a transmission line for feeding the antenna structures. The transmission line may include a positive signal conductor that is maintained at a desired distance from the conductive housing using a polymer sheet. A portion of the antenna structures may protrude between a microphone and a camera module. Plastic camera module housing structures may have an inner surface coated with a shielding metal. A U-shaped conductive fabric layer may be used as a grounding structure.

Abstract: An electronic device may have a conductive housing with an antenna window. A display cover layer may be mounted on the front face of the device. Antenna and proximity sensor structures may include a dielectric support structure with a notch. The antenna window may have a protruding portion that extends into the notch between the display cover layer and the antenna and proximity sensor structures. The antenna and proximity sensor structures may have an antenna feed that is coupled to a first conductive layer by a high pass circuit and capacitive proximity sensor circuitry that is coupled to the first conductive layer and a parallel second conductive layer by a low pass circuit. The first conductive layer may be formed from a metal coating on the support structure. The second conductive layer may be formed from patterned metal traces in a flexible printed circuit.

Abstract: An electronic device may include balance-fed antenna structures that do not have direct paths to ground. The antenna structures may serve as a Global Positioning System (GPS) antenna and may have a dipole structure having a first and second antenna resonating element arms. The antenna structures may include a conductive path that conveys antenna signals between a first feed terminal on the first antenna resonating element arm and a transmission line. The conductive path may overlap with the second antenna resonating element arm such that current flow through the conductive path induces corresponding current flow in the second antenna resonating element arm. The antenna structures may include an impedance matching short-circuit stub path that couples the first antenna resonating element arm to the second antenna resonating element arm. Choke inductors may be used to help block indirect paths from the antenna structures to ground through adjacent circuitry.

Abstract: An electronic device may be provided with a primary antenna that is used for transmitting and receiving signals and a secondary antenna that is used for receiving signals. The primary and secondary antennas may be used together in a diversity arrangement when receiving signals. The electronic device may have a transceiver. A phase shifter may be interposed between the transceiver and the secondary antenna. Control circuitry may select a communications band of interest for transmitting signals with the primary antenna. The control circuitry can adjust the phase shifter in real time based on which communications band of interest has been selected for transmission with the primary antenna. The phase shifter may impose a phase shift on signals carried between the secondary antenna and the transceiver that ensures that primary antenna efficiency degradation associated with the presence of the secondary antenna in the vicinity of the primary antenna is avoided.

Abstract: Antennas are provided for electronic devices such as portable computers. Multiple resonating elements may be formed on a flexible antenna resonating element substrate. The flexible antenna resonating element substrate may have a first antenna resonating element at one end and a second antenna resonating element at an opposing end. The flexible antenna resonating substrate may be wrapped around a dielectric carrier and mounted within an electronic device under an inactive display region and above a dielectric housing window. Conductive structures such as conductive housing structures may form antenna ground. The resonating elements and antenna ground may form first and second antennas. A parasitic antenna resonating element may form part of the first antenna.

Abstract: An electronic device may have an antenna for providing coverage in wireless communications bands of interest. The wireless communications bands may include first, second, third, and fourth communications bands. The antenna may have an antenna resonating element with first, second, and third arms and may have an antenna ground. The antenna ground may be formed form metal housing structures and other conductive structures in the electronic device. The first arm may be configured to exhibit an antenna resonance in the first and third communications bands. The second arm may be configured to exhibit an antenna resonance in the second communications band. The third arm may be configured to exhibit an antenna resonance in the fourth communications band. The third arm may be located between the first arm and the ground. A diagonal crossover path may pass over a return path and may couple the second and third arms.

Abstract: An electronic device may have an antenna for providing coverage in wireless communications bands of interest. The wireless communications bands may include a communications band at a first frequency. The antenna may have a parasitic antenna resonating element that supports a low efficiency resonance. In response to operation of the electronic device in free space, the low efficiency resonance will be located at a second frequency that is greater than the first frequency. In response to operation of the electronic device in proximity to a user's body or other external object, the antenna will be loaded and the low efficiency resonance associated with the parasitic antenna resonating element will shift to the communications band at the first frequency. The antenna may include a resonating element formed on a flexible printed circuit or a dielectric carrier such as a plastic support structure.

Abstract: An electronic device may be provided with a housing. The 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 a slot. An antenna feed may have a positive antenna terminal coupled to the peripheral metal member and a ground terminal coupled to the ground and may feed both an inverted-F antenna structure that is formed from the peripheral metal member and the ground and a slot antenna structure that is formed from the slot. Control circuitry may tune the antenna by controlling adjustable components that are coupled to the peripheral metal member. The adjustable components may include adjustable inductors and adjustable capacitors.

Abstract: An electronic device may have an antenna for providing coverage in wireless communications bands of interest such as a low frequency communications band, a middle frequency communications band, and a high frequency communications band. Slot structures in the antenna that might reduce efficiency in the high frequency communications band may be avoided by capacitively loading the antenna and omitting meandering paths in the antenna. A capacitor may be coupled between an antenna ground formed from a metal housing structure and an antenna resonating element having a curved shape that conforms to the shape of the edge of the electronic device. The capacitor may have interdigitated fingers and may be adjustable to tune the antenna. The antenna may transmit and receive radio-frequency signals through a display cover layer in a display and a dielectric antenna window portion of the housing.

Abstract: An electronic device may have a conductive housing with an antenna window. Antenna structures may be mounted adjacent to the antenna window. The antenna structures may have a dielectric carrier. Patterned metal antenna traces may be formed on the surface of the dielectric carrier. A proximity sensor may be formed from a flexible printed circuit mounted on the dielectric carrier. The flexible printed circuit may have a tail that contains a transmission line for feeding the antenna structures. The transmission line may include a positive signal conductor that is maintained at a desired distance from the conductive housing using a polymer sheet. A portion of the antenna structures may protrude between a microphone and a camera module. Plastic camera module housing structures may have an inner surface coated with a shielding metal. A U-shaped conductive fabric layer may be used as a grounding structure.

Abstract: Antenna structures for an antenna may be formed from a dielectric carrier with metal structures. The metal structures may be patterned to cover all sides of the dielectric carrier. The dielectric carrier may have a shape with six sides or other shape that creates a three-dimensional layout for the antenna structures. The antenna structures may have a tunable circuit that allows the antenna to be tuned. The tunable circuit may have first and second terminals coupled to one of the sides of the carrier. The metal structures may be configured to form an inverted-F antenna resonating element. Portions of the metal structures may form a first arm for an inverted-F antenna and portions of the metal structures may form a second arm for the inverted-F antenna. The antenna may operate in multiple communications bands. The tunable circuit may tune one band without significantly tuning other bands.

Abstract: An electronic device may have a conductive housing with an antenna window. A display cover layer may be mounted on the front face of the device. Antenna and proximity sensor structures may include a dielectric support structure with a notch. The antenna window may have a protruding portion that extends into the notch between the display cover layer and the antenna and proximity sensor structures. The antenna and proximity sensor structures may have an antenna feed that is coupled to a first conductive layer by a high pass circuit and capacitive proximity sensor circuitry that is coupled to the first conductive layer and a parallel second conductive layer by a low pass circuit. The first conductive layer may be formed from a metal coating on the support structure. The second conductive layer may be formed from patterned metal traces in a flexible printed circuit.

Abstract: A display cover layer may be mounted in an electronic device housing using housing structures such as corner brackets. A slot antenna may be formed from a corner bracket opening, metal traces on a hollow plastic support structure, or other conductive structures. The slot antenna may have a main portion with opposing ends. An antenna feed may be located at one of the ends. The slot antenna may have a slot with one or more bends. The bends may provide the slot antenna with a C-shaped outline. A side branch slot may extend from the main portion of the slot at a location between the two bends. The presence of the side branch slot may enhance antenna bandwidth. A hollow enclosure may serve as an antenna support structure and as a speaker box enclosing a speaker driver. The antenna feed may be positioned so as to overlap the speaker driver.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antennas. The antennas may include a non-tunable antenna and a tunable antenna. The non-tunable antenna may serve as the primary antenna in the electronic device and the tunable antenna may serve as a secondary antenna in the electronic device. The non-tunable antenna may be configured to operate in at least one communications band. The tunable antenna may contain adjustable circuitry. The adjustable circuitry may be used to tune the tunable antenna to cover the same communications band used by the non-tunable antenna. The tunable antenna may have a resonating element and an antenna ground. The adjustable circuit may be coupled between the resonating element and the antenna ground. The adjustable circuit may include electrical components such as inductors and capacitors and a radio-frequency switch for antenna tuning.

Abstract: A near-horizon antenna structure includes an upper radiating element having a straight conductive trace disposed on a planar surface of a non-conductive substrate, a rectangular lower radiating element serving as a ground plane disposed on the planar surface, and a feed point provided between the upper and lower radiating elements. When the planar surface is positioned vertically, the far-field effects of horizontal current flowing in opposite directions on the radiating elements cancel to provide an antenna pattern with increased gain in horizontal directions and reduced gain in vertical directions. A flat panel display and a portable communication device are also provided with one or more near-horizon antenna structures integrated therein.