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 be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. The internal ground plane and peripheral conductive housing member may be separated by a gap. The internal ground plane may be formed from sheet metal structures having engagement features such as tabs bent upwards at an angle. Plastic structures may be insert molded over the engagement features. When the internal ground plane is mounted in the electronic device, the plastic structures may bridge the gap between the internal ground plane and the peripheral conductive housing member. An adjustable structure such as a washer with a selectable thickness may be mounted to the peripheral conductive housing member opposing conductive structures across the gap. The thickness ma be adjusted to adjust antenna performance.

Abstract: Electronic devices may include antenna structures. The antenna structures may form an antenna having first and second feeds at different locations. Transceiver circuitry for transmitting and receiving radio-frequency antenna signals may be mounted on one end of a printed circuit board. Transmission line structures may be used to convey signals between an opposing end of the printed circuit board and the transceiver circuitry. The printed circuit board may be coupled to an antenna feed structure formed from a flexible printed circuit using solder connections. The flexible printed circuit may have a bend and may be screwed to conductive electronic device housing structures using one or more screws at one or more respective antenna feed terminals. Electrical components such as an amplifier circuit and filter circuitry may be mounted on the flexible printed circuit.

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 form an antenna having first and second feeds at different locations. The transceiver circuit may have a first circuit that handles communications using the first feed and may have a second circuit that handles communications using the second feed. A first filter may be interposed between the first feed and the first circuit and a second filter may be interposed between the second feed and the second circuit. The first and second filters and the antenna may be configured so that the first circuit can use the first feed without being adversely affected by the presence of the second feed and so that the second circuit can use the second feed without being adversely affected by the presence of the first feed.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. A conductive path may be formed that connects the peripheral conductive housing member and the internal ground plane. The conductive path may include a flex circuit. A metal structure may be welded to the peripheral conductive housing member. A solder pad and other traces in the flex circuit may be soldered to the metal structure at one end of the conductive path. At the other end of the conductive path, the flex circuit may be attached to the ground plane using a bracket, screw, and screw boss.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. A conductive path may be formed that connects the peripheral conductive housing member and the internal ground plane. The conductive path may include a flex circuit. The flex circuit can include a solder flow barrier to constrain flow of solder. A metal structure may be welded to the peripheral conductive housing member. A solder pad and other traces in the flex circuit may be soldered to the metal structure at one end of the conductive path. At the other end of the conductive path, the flex circuit may be attached to the ground plane using a bracket, screw, and screw boss.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. The internal ground plane and peripheral conductive housing member may be separated by a gap. The internal ground plane may be formed from sheet metal structures having engagement features such as tabs bent upwards at an angle. Plastic structures may be insert molded over the engagement features. When the internal ground plane is mounted in the electronic device, the plastic structures may bridge the gap between the internal ground plane and the peripheral conductive housing member. An adjustable structure such as a washer with a selectable thickness may be mounted to the peripheral conductive housing member opposing conductive structures across the gap. The thickness may be adjusted to adjust antenna performance.

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: Electronic devices may include antenna structures. The antenna structures may form an antenna having first and second feeds at different locations. Transceiver circuitry for transmitting and receiving radio-frequency antenna signals may be mounted on one end of a printed circuit board. Transmission line structures may be used to convey signals between an opposing end of the printed circuit board and the transceiver circuitry. The printed circuit board may be coupled to an antenna feed structure formed from a flexible printed circuit using solder connections. The flexible printed circuit may have a bend and may be screwed to conductive electronic device housing structures using one or more screws at one or more respective antenna feed terminals. Electrical components such as an amplifier circuit and filter circuitry may be mounted on the flexible printed circuit.

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 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 form an antenna having first and second feeds at different locations. The transceiver circuit may have a first circuit that handles communications using the first feed and may have a second circuit that handles communications using the second feed. A first filter may be interposed between the first feed and the first circuit and a second filter may be interposed between the second feed and the second circuit. The first and second filters and the antenna may be configured so that the first circuit can use the first feed without being adversely affected by the presence of the second feed and so that the second circuit can use the second feed without being adversely affected by the presence of the first feed.

Abstract: Custom antenna structures may be used to compensate for manufacturing variations in electronic device antennas. An electronic device antenna may have an antenna feed and conductive structures such as portions of a peripheral conductive electronic device housing member and other conductive antenna structures. The custom antenna structures compensate for manufacturing variations in the conductive antenna structures 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. Custom antenna structures may be interposed between an antenna feed terminal and the conductive housing member to adjust the effective location of the antenna feed. Custom antenna structures may include springs and custom paths on dielectric supports.

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: 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: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. The internal ground plane and peripheral conductive housing member may be separated by a gap. The internal ground plane may be formed from sheet metal structures having engagement features such as tabs bent upwards at an angle. Plastic structures may be insert molded over the engagement features. When the internal ground plane is mounted in the electronic device, the plastic structures may bridge the gap between the internal ground plane and the peripheral conductive housing member. An adjustable structure such as a washer with a selectable thickness may be mounted to the peripheral conductive housing member opposing conductive structures across the gap. The thickness may be adjusted to adjust antenna performance.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. A conductive path may be formed that connects the peripheral conductive housing member and the internal ground plane. The conductive path may include a flex circuit. The flex circuit can include a solder flow barrier to constrain flow of solder. A metal structure may be welded to the peripheral conductive housing member. A solder pad and other traces in the flex circuit may be soldered to the metal structure at one end of the conductive path. At the other end of the conductive path, the flex circuit may be attached to the ground plane using a bracket, screw, and screw boss.

Abstract: Electronic devices may be provided that contain wireless communications circuitry. The wireless communications circuitry may include antenna structures that are formed from an internal ground plane and a peripheral conductive housing member. A conductive path may be formed that connects the peripheral conductive housing member and the internal ground plane. The conductive path may include a flex circuit. A metal structure may be welded to the peripheral conductive housing member. A solder pad and other traces in the flex circuit may be soldered to the metal structure at one end of the conductive path. At the other end of the conductive path, the flex circuit may be attached to the ground plane using a bracket, screw, and screw boss.

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: Custom antenna structures may be used to compensate for manufacturing variations in electronic device antennas. An electronic device antenna may have an antenna feed and conductive structures such as portions of a peripheral conductive electronic device housing member and other conductive antenna structures. The custom antenna structures compensate for manufacturing variations in the conductive antenna structures 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. Custom antenna structures may be interposed between an antenna feed terminal and the conductive housing member to adjust the effective location of the antenna feed. Custom antenna structures may include springs and custom paths on dielectric supports.

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.