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 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 a 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. The wireless communications circuitry may include antenna structures. To accommodate manufacturing variations, the antenna structures and handheld electronic devices may be characterized by performing measurements such as antenna performance measurements. Appropriate antenna adjustments may be made during manufacturing of a handheld electronic device based on the characterizing measurements. An antenna may be formed using an inverted-F design in which an antenna flex circuit is mounted to a dielectric antenna support structure. Cavities in the support may be selectively filled with dielectric material and dielectric patches may be added to the antenna flex circuit to adjust the dielectric loading of the antenna. The length of a ground return path in the antenna may be adjusted by appropriate positioning of an electrical connector within the ground return path.

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 device under test (DUT) and at least one base station. 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 dual-polarized antennas may be coupled to the base station through downlink circuitry. A second group of dual-polarized antennas may be coupled to the base station through uplink circuitry. The uplink and downlink circuitry may each include a splitter/combiner, channel emulators, amplifier circuits, and switch circuitry. The channel emulators and amplifier circuits may be configured to provide desired path loss, spatial interference, and channel characteristics to model real-world wireless network transmission.

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 portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and an inverted-F antenna structure. The slot antenna portion of the hybrid antenna may be used to provide antenna coverage in a first communications band and the inverted-F antenna portion of the hybrid antenna may be used to provide antenna coverage in a second communications band. The second communications band need not be harmonically related to the first communications band. The electronic device may be formed from two portions. One portion may contain conductive structures that define the shape of the antenna slot. One or more dielectric-filled gaps in the slot may be bridged using conductive structures on another portion of the electronic device. A conductive trim member may be inserted into an antenna slot to trim the resonant frequency of the slot antenna portion of the hybrid antenna.

Abstract: A portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and a planar inverted-F antenna structure. The planar inverted-F antenna structure may be formed from traces on a flex circuit substrate. A backside trace may form a series capacitance for the planar inverted-F antenna structure. The antenna slot may have a perimeter that is defined by the location of conductive structures such as flex circuits, metal housing structures, a conductive bezel, printed circuit board ground conductors, and electrical components. Springs may be used in electrically connecting these conductive elements. A spring-loaded pin may be used as part of an antenna feed conductor. The pin may connect a transmission line path on a printed circuit board to the planar inverted-F antenna structure while allowing the planar inverted-F antenna structure to be removed from the device for rework or repair.

Abstract: Portable electronic devices are provided with wireless circuitry that includes antennas and antenna isolation elements. The antennas may include antennas that have multiple arms and that are configured to handle communications in multiple frequency bands. The antennas may also include one or more antennas that are configured to handle communications in a single frequency band. The antennas may be coupled to different radio-frequency transceivers. For example, there may be first, second, and third antennas and first and second transceivers. The first and third antennas may be coupled to the first transceiver and the second antenna may be coupled to the second transceiver. The antenna isolation elements may be interposed between the antennas and may serve to reduce radio-frequency interference between the antennas. There may be a first antenna isolation element between the first and second antennas and a second antenna isolation element between the second and third antennas.

Abstract: Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include antenna resonating elements such as dual-band antenna resonating elements that resonate in first and second communications bands. The antenna structures may also contain parasitic antenna elements such as elements that are operative in only the first or second communications band and elements that are operative in both the first and second communications bands. The antenna resonating elements and parasitic elements may be mounted on a common dielectric carrier. The dielectric carrier may be mounted within a slot or other opening in a conductive element. The conductive element may be formed from conductive housing structures in an electronic device such as a portable computer. The portable computer may have a clutch barrel with a dielectric cover. The dielectric cover may overlap and cover the slot and the dielectric carrier.

Abstract: Handheld electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures. An antenna may be located in an upper right corner of the handheld device as the handheld device is operated in a portrait mode. When the handheld device is rotated counterclockwise and operated in a landscape mode, the antenna is located in an unobstructed upper left corner of the device. The antenna may be formed from a strip of conductor. A proximal end of the strip of conductor may be connected to a transmission line. A distal end of the strip of conductor may be routed away from housing surfaces by bends formed in the strip. A printed circuit board in the handheld electronic device may have a hole. The distal end of the strip of conductor may be located adjacent to the hole.

Abstract: Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include antennas such as inverted-F antennas that contain antenna resonating elements and antenna ground elements. Antenna resonating elements may be formed from patterned conductive traces on substrates such as flex circuit substrates. Antenna ground elements may be formed from conductive device structures such as metal housing walls. Support and biasing structures such as dielectric support members and layer of foam may be used to support and bias antenna resonating elements against planar device structures. The planar device structures against which the antenna resonating elements are biased may be planar dielectric members such as transparent layers of display cover glass or other planar structures.

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 portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and an inverted-F antenna structure. The slot antenna portion of the hybrid antenna may be used to provide antenna coverage in a first communications band and the inverted-F antenna portion of the hybrid antenna may be used to provide antenna coverage in a second communications band. The second communications band need not be harmonically related to the first communications band. The electronic device may be formed from two portions. One portion may contain conductive structures that define the shape of the antenna slot. One or more dielectric-filled gaps in the slot may be bridged using conductive structures on another portion of the electronic device. A conductive trim member may be inserted into an antenna slot to trim the resonant frequency of the slot antenna portion of the hybrid antenna.

Abstract: A portable electronic device is provided that has a hybrid antenna. The hybrid antenna may include a slot antenna structure and a planar inverted-F antenna structure. The planar inverted-F antenna structure may be formed from traces on a flex circuit substrate. A backside trace may form a series capacitance for the planar inverted-F antenna structure. The antenna slot may have a perimeter that is defined by the location of conductive structures such as flex circuits, metal housing structures, a conductive bezel, printed circuit board ground conductors, and electrical components. Springs may be used in electrically connecting these conductive elements. A spring-loaded pin may be used as part of an antenna feed conductor. The pin may connect a transmission line path on a printed circuit board to the planar inverted-F antenna structure while allowing the planar inverted-F antenna structure to be removed from the device for rework or repair.

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: 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: A flex circuit may have test structures and antenna structures. The test structures may include test capacitors and transmission lines. The performance of the test structures may be measured using test equipment. Pass/fail criteria may be applied to the flex circuit based on the measured values. If the flex circuit is a failing circuit, flex circuit manufacturing settings may be adjusted. The performance of a radio-frequency (RF) cable may also be measured using the test equipment. Sample portions of the RF cable may be obtained and measured. Pass/fail criteria may be applied to the RF cable based on measured cable loss values. If the RF cable is a failing cable, RF cable manufacturing settings may be adjusted. Antenna structures associated with passing flex circuits and RF cable segments associated with passing sample RF cable segments may be incorporated into a wireless device during production device assembly.

Abstract: Electronic devices such as handheld devices may have wireless communications circuitry. The wireless communications circuitry may include a broadband antenna and circuitry that covers multiple communications bands. The broadband antenna may be formed from a parallel-fed dipole. The antenna may have first and second antenna resonating element regions on opposing sides of a slot. The slot may be an open slot that has one open end and one closed end. The slot may be formed from an opening in conductive housing structures in a conductive housing for an electronic device. The conductive housing structures may include sidewall structures, rear housing wall structures, and other conductive structures. The antenna may have a feed with a feed line that crosses the slot. An interposed dielectric substrate member may separate the feed line from the conductive structures. The feed line may have sections with different widths to minimize feed line length.

Abstract: Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. A display may be mounted on a front face of an electronic device. A conductive member such as a bezel may surround the display. Internal housing support structures such as a metal midplate member may be used to support the display. The midplate member may be connected between opposing edges of the bezel. The antenna structures may include an antenna formed from part of the midplate member and part of the bezel. Antenna image currents in the midplate member may be blocked by slots in the midplate member. The slots may be located adjacent to the antenna and may ensure that the antenna emits radio-frequency signals in a desired pattern. The slots may be angled and segmented.

Abstract: A method of manufacture for a portable computing device is described. In particular, methods and apparatus for assessing a quality of weld joints used to connect one or more components of the portable computing device are described. The weld joints can include one or more weld points. At a weld check station, using a vector network analyzer, a test signal generated can be passed through the weld joint and a response signal can be measured. The measured characteristics can be used to assess a quality of the weld joint. In one embodiment, the vector network analyzer can be used to generate a number of high frequency test signals that are passed through the weld to perform a time domain reflectometry measurement where the weld joint can be accepted or rejected based upon the measurement.