Abstract: Custom antenna structures may be used to improve antenna performance and to compensate for manufacturing variations in electronic device antennas. An electronic device antenna may include an antenna tuning element and conductive structures formed from portions of a peripheral conductive housing member and other conductive antenna structures. The antenna tuning element may be connected across a gap in the peripheral conductive housing member. The custom antenna structures may be used to couple the antenna tuning element to a fixed custom location on the peripheral conductive housing member to help satisfy design criteria and to compensate for manufacturing variations in the conductive antenna structures that could potentially lead to undesired variations in antenna performance. Custom antenna structures may include springs and custom paths on dielectric supports.

Abstract: A test system for testing a device under test (DUT) is provided. The test system may include a DUT receiving structure configured to receive the DUT during testing and a DUT retention structure that is configured to press the DUT against the DUT receiving structure so that DUT cannot inadvertently shift around during testing. The DUT retention structure may include a pressure sensor operable to detect an amount of pressure that is applied to the DUT. The DUT retention structure may be raised and lowered vertically using a manually-controlled or a computer-controlled positioner. The positioner may be adjusted using a coarse tuning knob and a fine tuning knob. The positioner may be calibrated such that the DUT retention structure applies a sufficient amount of pressure on the DUT during production testing.

Abstract: An electronic device may have wireless circuitry with antennas. An antenna may have an inverted-F antenna resonating element, an antenna ground, and other resonating element structures. A tip of the antenna resonating element and the antenna ground may be separated by a peripheral housing gap filled with plastic. The antenna may be sensitive to capacitance changes induced by the presence of a user's hand overlapping the gap or other portions of the antenna. A hand capacitance sensing electrode may be mounted in the plastic of the gap or elsewhere in the vicinity of the antenna. A transmission line may couple the hand capacitance sensing electrode to the antenna to retune the antenna in the event that the user's hand overlaps the antenna.

Abstract: Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may form a dual arm inverted-F antenna and an additional antenna such as a monopole antenna sharing a common antenna ground. The antenna structures may have three ports. A first antenna port may be coupled to an inverted-F antenna resonating element at a first location and a second antenna port may be coupled to the inverted-F antenna resonating element at a second location. A third antenna port may be coupled to the additional antenna. An adjustable component may be coupled to the first antenna port to tune the inverted-F antenna. The inverted-F antenna may be near-field coupled to the additional antenna so that the inverted-F antenna may serve as a tunable parasitic antenna resonating element that tunes the additional antenna.

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 antennas that are tuned, adjustable impedance matching circuitry, antenna port selection circuitry, and adjustable transceiver circuitry. Wireless circuit adjustments may be made by ascertaining a current usage scenario for the electronic device based on sensor data, information from cellular base station equipment or other external equipment, signal-to-noise ratio information or other signal information, antenna impedance measurements, and other information about the operation of the electronic device.

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: Various embodiments are directed toward low cost passive waveguide components. For example, various embodiments relate to passive waveguide components created busing a low cost fabrication technology. In some embodiments, a three-dimensional (3D) printing process is used to create a design mold and a non-conductive structure of the waveguide is formed using a plastic injection molding process. A conductive layer may be formed over the non-conductive structure such that the conductive layer creates an electrical feature of the passive waveguide component.

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 gap may be located under an opaque masking layer on the underside of a display cover glass associated with a display. The loop antenna resonating element may have a main body portion that includes the gap and may have an extended tail portion that extends between the display and conductive housing structures. The main body portion and extended tail portion may be configured to ensure that undesired waveguide modes are cut off during operation of the loop antenna.

Abstract: A manufacturing system for assembling wireless electronic devices is provided. The manufacturing system may include test stations for testing the radio-frequency performance of components that are to be assembled within the electronic devices. A reference test station may be calibrated using calibration coupons having known radio-frequency characteristics. The calibration coupons may include transmission line structures. The reference test station may measure verification standards to establish baseline measurement data. The verification standards may include circuitry having electrical components with given impedance values. Many verification coupons may be measured to enable testing for a wide range of impedance values. Test stations in the manufacturing system may subsequently measure the verification standards to generate test measurement data.

Abstract: Electronic devices may include antenna structures. The antenna structures may form an antenna having first and second feeds at different locations. A first transceiver may be coupled to the first feed using a first circuit. A second transceiver may be coupled to the second feed using a second circuit. The first and second feeds may be isolated from each other using the first and second circuits. The second circuit may have a notch filter that isolates the second feed from the first feed at operating frequencies associated with the first transceiver. The first circuit may include an adjustable component such as an adjustable capacitor. The adjustable component may be placed in different states depending on the mode of operation of the second transceiver to ensure that the first feed is isolated from the second feed.

Abstract: Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include antenna resonating elements, parasitic antenna resonating elements, and antenna ground structures. The antenna structures may include metal traces that are wrapped around an elongated plastic carrier. The plastic carrier may have metal traces that are coupled to a metal bracket using solder that protrudes through a hole in the metal bracket. A printed circuit board may be mounted between the metal bracket and a metal housing. The metal housing may have a protruding ridge portion that is gripped between prongs on the metal bracket. A cover may cover the metal traces on the elongated plastic carrier. The antenna structures may be mounted between hinge structures that couple upper and lower housing structures. The antenna structures may be configured to operate with comparable performance when the upper and lower housing structures are open and closed.

Abstract: Various embodiments provide for systems and methods for increased linear output power of a transmitter. An exemplary wireless communications system for transmitting an input signal comprises a predistorter module, a GaN power amplifier, a coupler, and an antenna. The predistorter module is configured to detect existing distortion by comparing the input signal to a feedback signal and generate a correction signal. The predistorter may adaptively adjust its operation to minimize the existing distortion due to GaN power amplifier nonlinear characteristics. The result is that the GaN power amplifier may send a power signal of improved linearity to the antenna. The coupler is configured to sample the amplified signal from the GaN power amplifier to generate the feedback signal. The antenna is configured to transmit the amplified signal.

Abstract: A wireless electronic device may contain at least one adjustable antenna tuning element for use in tuning the operating frequency range of the device. The antenna tuning element may include radio-frequency switches, continuously/semi-continuously adjustable components such as tunable resistors, inductors, and capacitors, and other load circuits that provide desired impedance characteristics. A test system that is used for performing passive radio-frequency (RF) testing on antenna tuning elements in partially assembled devices is provided. The test system may include an RF tester and a test host. The tester may be used to gather scattering parameter measurements from the antenna tuning element. The test host may be used to ensure that power and appropriate control signals are being supplied to the antenna tuning element so that the antenna tuning element is placed in desired tuning states during testing.

Abstract: Various embodiments provide for systems and methods for increased linear output power of a transmitter. An exemplary wireless communications system for transmitting an input signal comprises a predistorter module, a GaN power amplifier, a coupler, and an antenna. The predistorter module is configured to detect existing distortion by comparing the input signal to a feedback signal and generate a correction signal. The predistorter may adaptively adjust its operation to minimize the existing distortion due to GaN power amplifier nonlinear characteristics. The result is that the GaN power amplifier may send a power signal of improved linearity to the antenna. The coupler is configured to sample the amplified signal from the GaN power amplifier to generate the feedback signal. The antenna is configured to transmit the amplified signal.

Abstract: Radio frequency test systems for characterizing antenna performance in various radio coexistence scenarios are provided. In one suitable arrangement, a test system may be used to perform passive radio coexistence characterization. During passive radio coexistence characterization, at least one signal generator may be used to feed aggressor signals directly to antennas within an electronic device under test (DUT). The aggressor signals may generate undesired interference signals in a victim frequency band, which can then be received and analyzed using a spectrum analyzer. During active radio coexistence characterization, at least one radio communications emulator may be used to communicate with a DUT via a first test antenna. While the DUT is communicating with the at least one radio communications emulator, test signals may also be conveyed between DUT 10 and a second test antenna. Test signals conveyed through the second test antenna may be used in obtaining signal interference level measurements.

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. A hybrid antenna is also described herein. The hybrid antenna can include first and second flexible members capable of facilitating wireless communication, where the first and second flexible members are affixed to one another via a metal member.

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: 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: Various embodiments provide for waveguide assemblies which may be utilized in wireless communication systems. Various embodiments may allow for waveguide assemblies to be assembled using tools and methodologies that are simpler than the conventional alternatives. Some embodiments provide for a waveguide assembly that comprises a straight tubular portion configured to be shortened, using simple techniques and tools, in order to fit into a waveguide assembly. For instance, for some embodiments, the waveguide assembly may be configured such that the straight portion can be shortened, at a cross section of the portion, using a basic cutting tool, such a hacksaw. In some embodiments, the straight portion may be further configured such that regardless of whether the straight tubular portion is shortened, the waveguide assembly remains capable of coupling to flanges, which facilitate coupling the straight tubular portion to connectable assemblies, such as other waveguide assemblies, radio equipment, or antennas.

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.