Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antennas. An antenna may have an antenna ground that is configured to form a cavity for the antenna. The antenna ground may be formed on a support structure. The antenna ground may have an opening. The support structure may have a planar surface on which the opening is formed. A folded monopole antenna resonating element and an L-shaped conductive antenna element may be formed in the opening and may be capacitively coupled. The folded monopole antenna resonating element may have an end at which a positive antenna feed terminal is formed. A ground antenna feed terminal may be formed on the antenna ground. A segment of the antenna ground may extend between the ground antenna feed terminal and an end of the L-shaped conductive antenna element.

Abstract: An electronic device may have a cavity antenna. The cavity antenna may have a logo-shaped dielectric window. An antenna resonating element for the cavity antenna may be formed from conductive traces on a printed circuit board. An antenna resonating element may be formed from the traces. The antenna resonating element may be mounted on an antenna support structure. A conductive cavity structure for the cavity antenna may have a planar lip that is mounted flush with an interior surface of a conductive housing wall. The cavity structure may have more than one depth. Shallower planar portions of the cavity structure may lie in a plane. The antenna resonating element may be located between the plane of the shallow cavity walls and an external surface of the conductive housing wall.

Abstract: Electronic devices may be provided with antenna structures such as distributed loop antenna resonating element structures. A distributed loop antenna may be formed on an elongated dielectric carrier and may have a longitudinal axis. The distributed loop antenna may include a loop antenna resonating element formed from a sheet of conductive material that extends around the longitudinal axis. A gap may be formed in the sheet of conductive material. The loop antenna resonating element may be directly fed or indirectly fed. In indirect feeding arrangements, an antenna feed structure for indirectly feeding the loop antenna resonating element may be formed from a directly fed loop antenna structure on the elongated dielectric carrier.

Abstract: Damage to conductive material that serves as bridging connections between conductive structures within an electronic device may result in deficiencies in radio-frequency (RF) and other wireless communications. A test system for testing device structures under test is provided. Device structures under test may include substrates and a conductive material between the substrates. The test system may include a test fixture for increasing tensile or compressive stress on the device structures under test to evaluate the resilience of the conductive material. The test system may also include a test unit for transmitting RF test signals and receiving test data from the device structures under test. The received test data may include scattered parameter measurements from the device structures under test that may be used to determine if the device structures under test meet desired RF performance criteria.

Abstract: Antennas are provided for electronic devices such as portable computers. An electronic device may have a housing in which an antenna is mounted. The housing may be formed of conductive materials. A dielectric window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. A proximity sensor adjacent to the dielectric window may be used in detecting external objects. The antenna may have an antenna resonating element that is mounted against an inner surface of a display cover glass layer. The antenna resonating element may be mounted to an upper surface of a plastic carrier. An electromagnetic shield may be mounted on a lower surface of the plastic carrier above the proximity sensor.

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 may have a housing in which an antenna is mounted. An antenna window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. Near-field radiation limits may be satisfied by reducing transmit power when an external object is detected in the vicinity of the dielectric antenna window and the antenna. A capacitive proximity sensor may be used in detecting external objects in the vicinity of the antenna. The proximity sensor may have conductive layers separated by a dielectric. A capacitance-to-digital converter may be coupled to the proximity sensor by inductors. The capacitive proximity sensor may be interposed between an antenna resonating element and the antenna window. The capacitive proximity sensor may serve as a parasitic antenna resonating element and may be coupled to the housing by a capacitor.

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: A test system for characterizing an antenna tuning element is provided. The test system may include a test host, a radio-frequency tester, and a test fixture. The test system may calibrate the radio-frequency tester using known coaxial standards. The test system may then calibrate transmission line effects associated with the test fixture using a THRU-REFLECT-LINE calibration algorithm. The antenna tuning element may be mounted on a test socket that is part of the test fixture. While the antenna tuning element is mounted on the test socket, scattering parameter measurements may be obtained using the radio-frequency tester. An equivalent circuit model for the test socket can be obtained based on the measured scattering parameters and known characteristics of the antenna tuning element. Once the test socket has been characterized, an equivalent circuit model for the antenna tuning element can be obtained by extracting suitable modeling parameters from the measured scattering parameters.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. An electronic device may include a display mounted within a housing. A peripheral conductive member may run around the edges of the display and housing. Dielectric-filled gaps may divide the peripheral conductive member into individual segments. A ground plane may be formed within the housing from conductive housing structures, printed circuit boards, and other conductive elements. The ground plane and the segments of the peripheral conductive member may form antennas in upper and lower portions of the housing. The radio-frequency transceiver circuitry may implement receiver diversity using both the upper and lower antennas. The lower antenna may be used in transmitting signals. The upper antenna may be tuned using a tunable matching circuit.

Abstract: An electronic device may be provided with antenna structures. The antenna structures may be formed using a dielectric carrier structure. The antenna structures may have first and second loop antenna resonating elements. The first loop antenna resonating element may indirectly feed the second loop antenna resonating element. The second loop antenna resonating element may be a distributed loop element formed from multiple antenna resonating element subloops. The second loop antenna resonating element may be formed from a strip of metal with a width that loops around the dielectric carrier. An opening in the metal may separate first and second subloop antenna resonating elements from each other in the second loop antenna resonating element. Openings in the metal may form metal segments that collectively form an inductance for the first subloop. Antenna currents may flow through metal traces on the carrier and portions of an electronic device housing wall.

Abstract: A test system for testing multiple-input and multiple-output (MIMO) systems is provided. The test system may convey radio-frequency (RF) signals bidirectionally between a base station emulator and a device under test (DUT). The DUT may be placed within a test chamber during testing. An antenna mounting structure may surround the DUT. Multiple antennas may be mounted on the antenna mounting structure to transmit and receive RF signals to and from the DUT. A first group of antennas may be coupled to the base station emulator through downlink circuitry. A second group of antennas may be coupled to the base station emulator through uplink circuitry. The uplink and downlink circuitry may each include a splitter, channel emulators, and amplifier circuits. The channel emulators and amplifier circuits may be configured to provide desired path loss and channel characteristics to model real-world wireless network transmission.

Abstract: A test system for testing an antenna tuning element is provided. The test system may include a tester, a test fixture, and a probing structure. The probing structure may include probe tips configured to mate with corresponding solder bumps formed on a device under test (DUT) containing an antenna tuning element. The DUT may be tested in a shunt or series configuration. The tester may be electrically coupled to the test probe via first and second connectors on the test fixture. An adjustable load circuit that is coupled to the second connector may be configured in a selected state so that a desired amount of electrical stress may be presented to the DUT during testing. The tester may be used to obtain measurement results on the DUT. Systematic effects associated with the test structures may be de-embedded from the measured results to obtain calibrated results.

Abstract: An electronic device housing may have a base unit and a lid. Aligned antenna windows may be formed on opposing upper and lower surfaces of the base unit along a hinge. Antenna structures that are located between respective upper and lower antenna windows on the upper and lower surfaces may be based on a pair of antennas that are coupled to switching circuitry that can select which antenna to switch into use or may be based on an antenna having a position that may be adjusted relative to the upper and lower antenna windows using a mechanical coupling to the lid or using a positioner. A sensor such as a lid position sensor may monitor how the lid is positioned relative to the base unit. Information from the lid position sensor may be used in adjusting the antenna structures to optimize performance.

Abstract: A housing for a personal electronic device is described herein. The housing may include at least one modular subassembly configured to be arranged within an internal cavity of the housing. The at least one modular subassembly is aligned with a feature external to the housing, is affixed to an interior surface of the internal cavity, and is configured to function both as an antenna and as an internal support member of the housing.

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: Handheld electronic devices are provided that contain wireless communications circuitry having at least first and second antennas. An antenna isolation element reduces signal interference between the antennas, so that the antennas may be used in close proximity to each other. A planar ground element may be used as a ground by the first and second antennas. The first antenna may be formed using. a hybrid planar-inverted-F and slot arrangement in which a planar resonating element is located above a rectangular slot in the planar ground element. The second antenna may be formed from an L-shaped strip. The planar resonating element of the first antenna may have first and second arms. The first arm may resonate at a common frequency with the second antenna and may serve as the isolation element. The second arm may resonate at approximately the same frequency as the slot portion of the hybrid antenna.

Abstract: Antennas are provided for electronic devices such as portable computers. An electronic device may have a housing in which an antenna is mounted. The housing may have an antenna window for the antenna. The antenna window may be formed from dielectric or from antenna window slots in a conductive member such as a conductive wall of the electronic device housing. An antenna may have an antenna resonating element that is backed by a conductive antenna cavity. The antenna resonating element may have antenna resonating element slots or may be formed using other antenna configurations such as inverted-F configurations. The antenna cavity may have conductive vertical sidewalls and a conductive rear wall. The antenna cavity walls may be formed from conductive layers on a dielectric antenna support structure.

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.