Abstract: An electronic device may have peripheral conductive housing structures divided into first and second segments. First and second antennas may be formed from the segments and may be fed using a flexible printed circuit structure. The structure may include a first substrate attached to the first segment, a second substrate soldered to the first substrate and attached to the second segment, and a third substrate soldered to the second substrate. Third and fourth antennas may be formed on the first substrate whereas fifth and sixth antennas are be formed on the second substrate. The second substrate may be folded and may have a lateral area oriented perpendicular to the third, fourth, fifth, and sixth antennas. Modularly forming the structure in this way may maximize the flexibility with which the structure can accommodate other components, thereby minimizing the space consumption associated with mounting and feeding the antennas without sacrificing wireless performance.

Abstract: An electronic device may have peripheral conductive housing structures divided into first and second segments. First and second antennas may be formed from the segments and may be fed using a flexible printed circuit structure. The structure may include a first substrate attached to the first segment, a second substrate soldered to the first substrate and attached to the second segment, and a third substrate soldered to the second substrate. Third and fourth antennas may be formed on the first substrate whereas fifth and sixth antennas are be formed on the second substrate. The second substrate may be folded and may have a lateral area oriented perpendicular to the third, fourth, fifth, and sixth antennas. Modularly forming the structure in this way may maximize the flexibility with which the structure can accommodate other components, thereby minimizing the space consumption associated with mounting and feeding the antennas without sacrificing wireless performance.

Abstract: Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. An inverted-F antenna may have first and second short circuit legs and a feed leg. The first and second short circuit legs and the feed leg may be connected to a folded antenna resonating element arm. The antenna resonating element arm and the first short circuit leg may be formed from portions of a conductive electronic device bezel. The folded antenna resonating element arm may have a bend. The bezel may have a gap that is located at the bend. Part of the folded resonating element arm may be formed from a conductive trace on a dielectric member. A spring may be used in connecting the conductive trace to the electronic device bezel portion of the antenna resonating element arm.

Abstract: A test system is provided for performing radio-frequency tests on an electronic device under test (DUT) having multiple antennas. The test system may include a test unit for generating radio-frequency test signals, a test enclosure, and a test antenna fixture. The test fixture may include tunable antenna circuitry, antenna tuning elements, a test sensor, a microcontroller, a battery, and a solar cell that charges the battery, each of which is mounted on a test fixture within the test enclosure. The test sensor may be used to detect stimuli issued by the DUT. In response to detecting the stimuli, the microcontroller may send control signals to the antenna tuning elements to configure the antenna circuitry in different modes. Each of the different modes may be optimized to test a selected one of the multiple antennas in the DUT when operating using different radio access technologies and at different frequencies.

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: Electronic device structures such as structures containing antennas, connectors, welds, electronic device components, conductive housing structures, and other structures can be tested for faults using a non-contact test system. The test system may include a vector network analyzer or other test unit that generates radio-frequency tests signals in a range of frequencies. The radio-frequency test signals may be transmitted to electronic device structures under test using an antenna probe that has one or more test antennas. The antenna probe may receive corresponding radio-frequency signals. The transmitted and received radio-frequency test signals may be analyzed to determine whether the electronic device structures under test contain a fault.

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 be formed from an antenna resonating element arm and an antenna ground. The antenna resonating element arm may have a shorter portion that resonates at higher communications band frequencies and a longer portion that resonates at lower communications band frequencies. A short circuit branch may be coupled between the shorter portion of the antenna resonating element arm and the antenna ground. A series-connected inductor and switch may be coupled between the longer portion of the antenna resonating element arm and the antenna ground. An antenna feed branch may be coupled between the antenna resonating element arm and the antenna ground at a location that is between the short circuit branch and the series-connected inductor and switch.

Abstract: A test station may include a test host, a test unit, and a test enclosure. A device under test (DUT) having at least first and second antennas may be placed in the test enclosure during production testing. Radio-frequency test signals may be conveyed from the test unit to the DUT using a test antenna in the test enclosure. In a first time period during which the performance of the first antenna is being tested, the DUT may be oriented in a first position such that path loss between the first antenna and the test antenna is minimized. In a second time period during which the performance of the second antenna is being tested, the DUT may be oriented in a second position such that path loss between the second antenna and the test antenna is minimized. The DUT is marked as a passing DUT if gathered test data is satisfactory.

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: Custom antenna structures may be used to compensate for manufacturing variations in electronic device antennas. An antenna may have an antenna feed and conductive structures such as portions of a peripheral conductive electronic device housing member. The custom antenna structures compensate for manufacturing variations that could potentially lead to undesired variations in antenna performance. The custom antenna structures may make customized alterations to antenna feed structures or conductive paths within an antenna. An antenna may be formed from a conductive housing member that surrounds an electronic device. The custom antenna structures may be formed from a printed circuit board with a customizable trace. The customizable trace may have a contact pad portion on the printed circuit board. The customizable trace may be customized to connect the pad to a desired one of a plurality of contacts associated with the conductive housing member to form a customized antenna feed terminal.

Abstract: Electronic devices may be tested using a test station with a test fixture. The test fixture may include a first holding structure in which a device under test may be placed and a second holding structure for supporting test probes. The second holding structure may be mated with a test probe alignment structure during test station setup operations. The test probe alignment structure may include registration features configured to set the relative position of the first and second holding structures to a known configuration and may include test probe alignment features that can be used to correctly position the placement of the test probes. If at least one of the test probes is not sufficiently aligned to its corresponding alignment feature, the test probe alignment structures will not be able to engage properly with the second holding structure, and the position of the problematic test probe may be adjusted accordingly.

Abstract: Conductive electronic device structures such as a conductive housing member that forms part of an antenna may be tested during manufacturing. A test system may be provided that has a capacitive coupling probe. The probe may have electrodes. The electrodes may be formed from patterned metal structures in a dielectric substrate. A test unit may provide radio-frequency test signals in a range of frequencies. The radio-frequency test signals may be applied to the conductive housing member or other conductive structures under test using the electrodes. Complex impedance data, forward transfer coefficient data, or other data may be used to determine whether the structures are faulty. A fixture may be used to hold the capacitive coupling probe in place against the conductive electronic device structures during testing.

Abstract: An electronic device may have tunable antenna structures. A tunable antenna may have an antenna resonating element and an antenna ground. An adjustable electronic component such as an adjustable capacitor, adjustable inductor, or adjustable phase-shift element may be used in tuning the antenna. An impedance matching circuit may be coupled between the tunable antenna and a radio-frequency transceiver. The adjustable electronic component may be coupled to the antenna resonating element or other structures in the antenna or may form part of the impedance matching circuit, a transmission line, a parasitic antenna element, or other antenna structures. During manufacturing, manufacturing variations may cause the performance of the tunable antenna to deviate from desired specifications. Calibration operations may be performed to identify compensating adjustments to be made with the adjustable electronic component.

Abstract: A portable test chamber with an open top may serve as a field testing apparatus for wireless testing of electronic devices. A wireless device under test may be mounted within a cavity in the test chamber. The cavity may be surrounded by a dielectric lining of anechoic material. A layer of electromagnetic shielding such as metal foil may cover the outer surfaces of the dielectric lining. The chamber may have a box shape with a rectangular opening at its top. Satellite navigation system signals or other wireless signals may be received through the opening at the top of the test chamber during testing. The electromagnetic shielding may reduce the effects of multipath interference during field tests.

Abstract: A wireless electronic device may contain at least one 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 station may be used to measure the radio-frequency characteristics associated with the tuning element. The test station may provide adjustable temperature, power, and impedance control to help emulate a true application environment for the tuning element without having to place the tuning element within an actual device during testing. The test system may include at least one signal generator and a tester for measuring harmonic distortion values and may include at least two signal generators and a tester for measuring intermodulation distortion values.

Abstract: Electronic devices are provided that contain wireless communications circuitry. The wireless communications circuitry may include radio-frequency transceiver circuitry and antenna structures. An inverted-F antenna may have first and second short circuit legs and a feed leg. The first and second short circuit legs and the feed leg may be connected to a folded antenna resonating element arm. The antenna resonating element arm and the first short circuit leg may be formed from portions of a conductive electronic device bezel. The folded antenna resonating element arm may have a bend. The bezel may have a gap that is located at the bend. Part of the folded resonating element arm may be formed from a conductive trace on a dielectric member. A spring may be used in connecting the conductive trace to the electronic device bezel portion of the antenna resonating element arm.

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 device structures such as a conductive housing member that forms part of an antenna may be tested during manufacturing. A test system may be provided that includes a test probe configured to energize the conductive housing member or other conductive structures under test and that includes temporary test structures that may be placed in the vicinity of or in direct contact with the device structures during testing to facilitate detection of manufacturing defects. Test equipment such as a network analyzer may provide radio-frequency test signals in a range of frequencies. An antenna probe may be used to gather corresponding wireless radio-frequency signal data. Forward transfer coefficient data may be computed from the transmitted and received radio-frequency signals. The forward transfer coefficient data or other test data may be compared to reference data to determine whether the device structures contain a fault.

Abstract: Wireless electronic devices may include wireless communications circuitry such as a transceiver, antenna, and other wireless circuitry. The transceiver may be coupled to the antenna through a bidirectional switch connector. The switch connector may mate with a corresponding radio-frequency test probe that is connected to radio-frequency test equipment. When the test probe is mated with the switch connector, the transceiver may be decoupled from the antenna. During transceiver testing, radio-frequency test signals may be conveyed between the test unit and the transceiver using the test probe. During antenna testing, radio-frequency test signals may be conveyed between the test unit and the antenna using the test probe. Transceiver testing and antenna testing may, if desired, be conducted in parallel using the test probe.

Abstract: A wireless electronic device may be provided with antenna structures. The antenna structures may be formed from an antenna ground and an array of antenna resonating elements formed along its periphery. The antenna resonating elements may be formed from metal traces on a dielectric support structure that surrounds the antenna ground. The electronic device may be tested using a test system for detecting the presence of manufacturing/assembly defects. The test system may include an RF tester and a test fixture. The device under test (DUT) may be attached to the test fixture during testing. Multiple test probes arranged along the periphery of the DUT may be used to transmit and receive RF test signals for gathering scattering parameter measurements on the device under test. The scattering parameter measurements may then be compared to predetermined threshold values to determine whether the DUT contains any defects.