Abstract: An electronic device may include wireless circuitry that is configured to transmit wireless signals during operation. A maximum transmit power level may be established that serves as a cap on how much power is transmitted from the electronic device. Adjustments may be made to the maximum transmit power level in real time based on sensor signals and other information on the operating state of the electronic device. The sensor signals may include motion signals from an accelerometer. The sensor signals may also include ultrasonic sound detected by a microphone. Device orientation data may be used by the device to select whether to measure the ultrasonic sound using a front facing or rear facing microphone. Maximum transmit power level may also be adjusted based on whether or not sound is playing through an ear speaker in the device.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and first and second antennas. An electronic device may include a housing. The first antenna may be located at an upper end of the housing and the second antenna may be located at a lower end of the housing. A peripheral conductive member may run around the edges of the housing and may be used in forming the first and second antennas. The radio-frequency transceiver circuitry may have a transmit-receive port and a receive port. Switching circuitry may connect the first antenna to the transmit-receive port and the second antenna to the receiver port or may connect the first antenna to the receive port and the second antenna to the transmit-receive port.

Abstract: An electronic device may have an antenna for providing coverage in wireless communications bands of interest such as a low frequency communications band and a high frequency communications band. The antenna may have an antenna ground and an antenna resonating element. The antenna resonating element may have a high band arm that contributes to a first high band resonance in the high band and may have a low band arm that exhibits a low band resonance in the low band. A passive filter that is coupled between first and second portions of the antenna resonating element may be configured to exhibit a short circuit impedance associated with a bypass path that allows the antenna resonating element to contribute to a second high band resonance in the high band. A tunable inductor coupled to the antenna resonating element may be used to tune the low band resonance.

Abstract: An electronic device may be provided with shared antenna structures that can be used to form both a near-field-communications antenna such as a loop antenna and a non-near-field communications antenna such as an inverted-F antenna. The antenna structures may include conductive structures such as metal traces on printed circuits or other dielectric substrates, internal metal housing structures, or other conductive electronic device housing structures. A main resonating element arm may be separated from an antenna ground by an opening. A non-near-field communications antenna return path and antenna feed path may span the opening. A balun may have first and second electromagnetically coupled inductors. The second inductor may have terminals coupled across differential signal terminals in a near-field communications transceiver. The first inductor may form part of the near-field communications loop antenna.

Abstract: A handheld electronic device may be provided that contains a conductive housing and other conductive elements. The conductive elements may form an antenna ground plane. One or more antennas for the handheld electronic device may be formed from the ground plane and one or more associated antenna resonating elements. Transceiver circuitry may be connected to the resonating elements by transmission lines such as coaxial cables. Ferrules may be crimped to the coaxial cables. A bracket with extending members may be crimped over the ferrules to ground the coaxial cables to the housing and other conductive elements in the ground plane. The ground plane may contain an antenna slot. A dock connector and flex circuit may overlap the slot in a way that does not affect the resonant frequency of the slot. Electrical components may be isolated from the antenna using isolation elements such as inductors and resistors.

Abstract: An electronic device has wireless communications circuitry including an adjustable antenna system coupled to a radio-frequency transceiver. The adjustable antenna system may include one or more adjustable electrical components that are controlled by storage and processing circuitry in the electronic device. The adjustable electrical components may include switches and components that can be adjusted between numerous different states. The adjustable electrical components may be coupled between antenna system components such as transmission line elements, matching network elements, antenna elements and antenna feeds. By adjusting the adjustable electrical components, the storage and processing circuitry can tune the adjustable antenna system to ensure that the adjustable antenna system covers communications bands of interest.

Abstract: A computer stylus may have an elongated body with a metal tube that serves as an antenna ground for an antenna. An antenna resonating element for the antenna may be formed from metal traces that wrap around a longitudinal axis for the elongated body. The antenna may be an inverted-F antenna. A ground antenna feed terminal for the inverted-F antenna may be coupled to the metal tube with a sheet metal member, conductive fabric, and solder. A clip may run along a side of the elongated body at a location that does not overlap the metal traces of the antenna resonating element. The antenna may be fed at a location on an opposing side of the elongated body from the clip. Antenna signals from the inverted-F antenna may be reflected towards the tip by metal structures at the end of the elongated body opposing the tip.

Abstract: Electronic devices may be provided with antenna structures. The antenna structures may be used in wirelessly transmitting and receiving radio-frequency signals. Antenna structures may be formed from molded dielectric substrates. Patterned conductive material may be formed on the dielectric substrates. The dielectric substrates may be formed from molded materials such as glass or ceramic. Sheets of dielectric or dielectric powder may be compressed to form a dielectric substrate of a desired shape. The patterned conductive material may be formed from metallic paint or other conductors. A hollow antenna chamber may be formed by joining molded dielectric structures. An antenna such as an indirectly-fed loop antenna or other antennas may be formed from the molded dielectric substrates and patterned conductors.

Abstract: A handheld electronic device may be provided that contains a conductive housing and other conductive elements. Transceiver circuitry, such as radio frequency (RF) transceiver circuitry configured to transmit and receive RF signals, may be connected to the resonating elements by transmission lines such as coaxial cables. The electronic device may have an integrated touch screen display in which a user can control the device by interacting directly with the display.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and first and second antennas. An electronic device may include a housing. The first antenna may be located at an upper end of the housing and the second antenna may be located at a lower end of the housing. A peripheral conductive member may run around the edges of the housing and may be used in forming the first and second antennas. The radio-frequency transceiver circuitry may have a transmit-receive port and a receive port. Switching circuitry may connect the first antenna to the transmit-receive port and the second antenna to the receiver port or may connect the first antenna to the receive port and the second antenna to the transmit-receive port.

Abstract: An electronic device has wireless communications circuitry including an adjustable antenna system coupled to a radio-frequency transceiver. The adjustable antenna system may include one or more adjustable electrical components that are controlled by storage and processing circuitry in the electronic device. The adjustable electrical components may include switches and components that can be adjusted between numerous different states. The adjustable electrical components may be coupled between antenna system components such as transmission line elements, matching network elements, antenna elements and antenna feeds. By adjusting the adjustable electrical components, the storage and processing circuitry can tune the adjustable antenna system to ensure that the adjustable antenna system covers communications bands of interest.

Abstract: A handheld electronic device may be provided that contains a conductive housing and other conductive elements. The conductive elements may form an antenna ground plane. One or more antennas for the handheld electronic device may be formed from the ground plane and one or more associated antenna resonating elements. Transceiver circuitry may be connected to the resonating elements by transmission lines such as coaxial cables. Ferrules may be crimped to the coaxial cables. A bracket with extending members may be crimped over the ferrules to ground the coaxial cables to the housing and other conductive elements in the ground plane. The ground plane may contain an antenna slot. A dock connector and flex circuit may overlap the slot in a way that does not affect the resonant frequency of the slot. Electrical components may be isolated from the antenna using isolation elements such as inductors and resistors.

Abstract: A handheld electronic device may be provided that contains wireless communications circuitry. The handheld electronic device may have a housing and a display. The display may be attached to the housing using a conductive bezel. The handheld electronic device may have one or more antennas for supporting wireless communications. A ground plane in the handheld electronic device may serve as ground for one or more of the antennas. The ground plane and bezel may define an opening. A rectangular slot antenna or other suitable slot antenna may be formed from or within the opening. One or more antenna resonating elements may be formed above the slot. An electrical switch that bridges the slot may be used to modify the perimeter of the slot so as to tune the communications bands of the handheld electronic device.

Abstract: A handheld electronic device may be provided that contains a conductive housing and other conductive elements. Transceiver circuitry, such as radio frequency (RF) transceiver circuitry configured to transmit and receive RF signals, may be connected to the resonating elements by transmission lines such as coaxial cables. The electronic device may have an integrated touch screen display in which a user can control the device by interacting directly with the display.

Abstract: A handheld electronic device may be provided that contains a conductive housing and other conductive elements. Transceiver circuitry, such as radio frequency (RF) transceiver circuitry configured to transmit and receive RF signals, may be connected to the resonating elements by transmission lines such as coaxial cables. The electronic device may have an integrated touch screen display in which a user can control the device by interacting directly with the display.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and first and second antennas. An electronic device may include a housing. The first antenna may be located at an upper end of the housing and the second antenna may be located at a lower end of the housing. A peripheral conductive member may run around the edges of the housing and may be used in forming the first and second antennas. The radio-frequency transceiver circuitry may have a transmit-receive port and a receive port. Switching circuitry may connect the first antenna to the transmit-receive port and the second antenna to the receiver port or may connect the first antenna to the receive port and the second antenna to the transmit-receive port.

Abstract: An electronic device may have a display. A display cover layer and a transparent inner display member may overlap a display pixel layer. The display pixel layer may have an array of display pixels for displaying images for a user. A touch sensor layer may be interposed between the display pixel layer and the transparent display member. A ferromagnetic shielding layer may be mounted below the display pixel layer. A flexible printed circuit containing coils of metal signal lines that form a near-field communications loop antenna may be interposed between the ferromagnetic shielding layer and the display pixel layer. A non-near-field antenna such as an inverted-F antenna may have a resonating element mounted on an inner surface of the display cover layer. The resonating element may be interposed between the transparent display member and the display cover layer.

Abstract: A handheld electronic device may be provided that contains a conductive housing and other conductive elements. The conductive elements may form an antenna ground plane. One or more antennas for the handheld electronic device may be formed from the ground plane and one or more associated antenna resonating elements. Transceiver circuitry may be connected to the resonating elements by transmission lines such as coaxial cables. Ferrules may be crimped to the coaxial cables. A bracket with extending members may be crimped over the ferrules to ground the coaxial cables to the housing and other conductive elements in the ground plane. The ground plane may contain an antenna slot. A dock connector and flex circuit may overlap the slot in a way that does not affect the resonant frequency of the slot. Electrical components may be isolated from the antenna using isolation elements such as inductors and resistors.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include conductive housing structures such as a peripheral conductive housing member. The antenna structures may be based on an inverted-F antenna resonating element or other types of antenna resonating element. An electronic device may have near field communications circuitry and non-near-field communications circuitry such as cellular telephone, satellite navigation system, or wireless local area network transceiver circuitry. Antenna structures may be configured to handle signals associated with the non-near-field communications circuitry. The antenna structures may also have portions that form a near field communications loop antenna for handling signals associated with the near field communications circuitry.

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.