Abstract: An electronic device may include a housing and four antennas at respective corners of the housing. Cellular telephone transceiver circuitry may concurrently convey signals at one or more of the same frequencies over one or more of the four antennas using a multiple-input multiple-output (MIMO) scheme. In order to isolate adjacent antennas, dielectric-filled openings may be formed in conductive walls of the housing to divide the walls into segments that are used to form resonating element arms for the antennas. If desired, first and second antennas may include resonating element arms formed from a wall without any gaps. The first and second antennas may include adjacent return paths. A magnetic field associated with currents for the first antenna may cancel out with a magnetic field associated with currents for the second antenna at the adjacent return paths, thereby serving to electromagnetically isolate the first and second antennas.

Abstract: An electronic device may include a conductive housing and an antenna. The antenna may include an arm formed from a first segment of the housing. A gap may separate the first segment from a second segment. The antenna may include a feed coupled to a transmission line having a signal conductor. The feed may include first and second positive terminals on the first segment and a third positive terminal on the second segment. An adjustable component may be coupled between the first and third terminals. The signal conductor may be coupled to the first terminal. A wide conductive trace may be coupled between the signal conductor and the second terminal. A switch may be interposed on the signal conductor. The second terminal may cover a cellular low band when the switch is open. The first terminal may cover the cellular low band and higher bands when the switch is closed.

Abstract: A disclosed antenna assembly includes a first flexible circuit having a first signal line, at least one first shielding layer, and a first attachment region. The first attachment region includes a first signal pad and first shielding pads disposed around the first signal pad. The antenna assembly further includes a second flexible circuit having a second signal line, at least one second shielding layer, and a second attachment region. The second attachment region includes a second signal pad and second shielding pads disposed around the second signal pad. The first attachment region is attached to the second attachment region.

Abstract: An electronic device may include a housing and four antennas at respective corners of the housing. Cellular telephone transceiver circuitry may concurrently convey signals at one or more of the same frequencies over one or more of the four antennas using a multiple-input multiple-output (MIMO) scheme. In order to isolate adjacent antennas, dielectric-filled openings may be formed in conductive walls of the housing to divide the walls into segments that are used to form resonating element arms for the antennas. If desired, first and second antennas may include resonating element arms formed from a wall without any gaps. The first and second antennas may include adjacent return paths. A magnetic field associated with currents for the first antenna may cancel out with a magnetic field associated with currents for the second antenna at the adjacent return paths, thereby serving to electromagnetically isolate the first and second antennas.

Abstract: An electronic device may include a housing and four antennas at respective corners of the housing. Cellular telephone transceiver circuitry may concurrently convey signals at one or more of the same frequencies over one or more of the four antennas using a multiple-input multiple-output (MIMO) scheme. In order to isolate adjacent antennas, dielectric-filled openings may be formed in conductive walls of the housing to divide the walls into segments that are used to form resonating element arms for the antennas. If desired, first and second antennas may include resonating element arms formed from a wall without any gaps. The first and second antennas may include adjacent return paths. A magnetic field associated with currents for the first antenna may cancel out with a magnetic field associated with currents for the second antenna at the adjacent return paths, thereby serving to electromagnetically isolate the first and second antennas.

Abstract: An electronic device may include a conductive housing and an antenna. The antenna may include an arm formed from a first segment of the housing. A gap may separate the first segment from a second segment. Respective first and second slots may separate an antenna ground from the first and second segments. The antenna may have a first positive antenna feed terminal on the first segment and a second positive antenna feed terminal on the second segment. A transmission line may include a signal conductor having a first branch coupled to the first positive antenna feed terminal and a second branch coupled to the second positive antenna feed terminal. A switch may be interposed on the second branch for switching the antenna between a first mode in which the second slot is directly fed and a second mode in which the second segment is indirectly fed by the first segment.

Abstract: An electronic device may include a peripheral conductive wall. A gap in the wall may divide the wall into first and second segments. The device may include a first antenna having a first resonating element arm formed from the first segment and a second antenna having a second resonating element arm formed from the second segment. A non-near-field communications transceiver may perform multiple-input and multiple-output (MIMO) operations using the first and second antennas. The gap may provide satisfactory isolation between the first and second antennas while the first and second antennas perform MIMO operations. Near-field communications circuitry may convey near-field communications signals over a conductive loop path that includes portions of the first and second segments and the antenna ground. The volume of the conductive loop path may extend across substantially all of a width of the electronic device.

Abstract: A disclosed antenna assembly includes a first flexible circuit having a first signal line, at least one first shielding layer, and a first attachment region. The first attachment region includes a first signal pad and first shielding pads disposed around the first signal pad. The antenna assembly further includes a second flexible circuit having a second signal line, at least one second shielding layer, and a second attachment region. The second attachment region includes a second signal pad and second shielding pads disposed around the second signal pad. The first attachment region is attached to the second attachment region.

Abstract: An electronic device may include a conductive housing and an antenna. The antenna may include an arm formed from a first segment of the housing. A gap may separate the first segment from a second segment. The antenna may include a feed coupled to a transmission line having a signal conductor. The feed may include first and second positive terminals on the first segment and a third positive terminal on the second segment. An adjustable component may be coupled between the first and third terminals. The signal conductor may be coupled to the first terminal. A wide conductive trace may be coupled between the signal conductor and the second terminal. A switch may be interposed on the signal conductor. The second terminal may cover a cellular low band when the switch is open. The first terminal may cover the cellular low band and higher bands when the switch is closed.

Abstract: An electronic device may include antennas, a ground, and a housing. First and second gaps in the housing may define a segment that forms a resonating element for a first antenna. First, second, third, and fourth antenna feeds may be coupled between the segment and ground. Control circuitry may control adjustable components to place the device in first, second, third, or fourth modes. In the first and second modes, the first and fourth feeds convey signals at the same frequency using a multiple-input and multiple-output scheme while the second and third feeds are inactive. In the third mode, the second feed is active and the first, third, and fourth feeds are inactive. In the fourth mode, the third feed is active and the first, second, and fourth antenna feeds are inactive. Isolating return paths may be coupled between the segment and ground in the first and second modes.

Abstract: A consumer electronic product includes a switchable inductor array coupled to the RF antenna, the switchable inductor array comprising inductive elements and a switch circuit coupled to the inductor array to select at least one of the inductive elements and couple the selected inductive element with the RF antenna. The product can further include an assembly having a mesh that is strengthened by a stiffener. A multi-layer adhesive have a conductive layer that can be used to shield the RF antenna and adhesive layers that can provide adhesion between the stiffener and the housing of the product. The assembly can be covered by a cowling that is made of metal to provide further shielding. To reduce potential coupling between the RF antenna and the cowling, the cowling can have a portion that is formed of plastic to distance its metal portion from the antenna.

Abstract: An electronic device may include a conductive housing and an antenna. The antenna may include an arm formed from a first segment of the housing. A gap may separate the first segment from a second segment. Respective first and second slots may separate an antenna ground from the first and second segments. The antenna may have a first positive antenna feed terminal on the first segment and a second positive antenna feed terminal on the second segment. A transmission line may include a signal conductor having a first branch coupled to the first positive antenna feed terminal and a second branch coupled to the second positive antenna feed terminal. A switch may be interposed on the second branch for switching the antenna between a first mode in which the second slot is directly fed and a second mode in which the second segment is indirectly fed by the first segment.

Abstract: An electronic device may include a peripheral conductive wall. A gap in the wall may divide the wall into first and second segments. The device may include a first antenna having a first resonating element arm formed from the first segment and a second antenna having a second resonating element arm formed from the second segment. A non-near-field communications transceiver may perform multiple-input and multiple-output (MIMO) operations using the first and second antennas. The gap may provide satisfactory isolation between the first and second antennas while the first and second antennas perform MIMO operations. Near-field communications circuitry may convey near-field communications signals over a conductive loop path that includes portions of the first and second segments and the antenna ground. The volume of the conductive loop path may extend across substantially all of a width of the electronic device.

Abstract: An electronic device may have wireless circuitry with antennas. An antenna resonating element arm for an antenna may be formed from peripheral conductive structures running along the edges of a device housing. Elongated conductive members may longitudinally divide openings between the peripheral conductive housing structures and the ground. The elongated conductive members may extend from an internal ground to outer ends of the elongated conductive members that are located adjacent to the gaps. Transmission lines may extend along the elongated conductive members to antenna feeds at the outer ends. The elongated conductive members may form open slots that serve as slot antenna resonating elements for the antenna.

Abstract: An electronic device may be provided with wireless circuitry. The wireless circuitry may include one or more antennas. The antennas may include cellular telephone antennas, wireless local area network antennas, antenna structures for receiving satellite navigation system signals, and other antennas. An antenna may have an antenna resonating element such as an inverted-F antenna resonating element. The inverted-F antenna resonating element may have an inverted-F antenna resonating element arm formed from metal traces on a flexible printed circuit. The flexible printed circuit may be soldered to an antenna grounding clip. A screw may attach the clip, a speaker tab, a connector bracket, and other metal structures to a metal device housing that serves as ground for the antenna. The screw may be isolated from the antenna grounding clip and the other metal structures by an insulating structure such as an insulating gasket.

Abstract: An electronic device may include a peripheral conductive wall. A gap in the wall may divide the wall into first and second segments. The device may include a first antenna having a first resonating element arm formed from the first segment and a second antenna having a second resonating element arm formed from the second segment. A non-near-field communications transceiver may perform multiple-input and multiple-output (MIMO) operations using the first and second antennas. The gap may provide satisfactory isolation between the first and second antennas while the first and second antennas perform MIMO operations. Near-field communications circuitry may convey near-field communications signals over a conductive loop path that includes portions of the first and second segments and the antenna ground. The volume of the conductive loop path may extend across substantially all of a width of the electronic device.

Abstract: An electronic device may include antennas, a ground, and a housing. First and second gaps in the housing may define a segment that forms a resonating element for a first antenna. First, second, third, and fourth antenna feeds may be coupled between the segment and ground. Control circuitry may control adjustable components to place the device in first, second, third, or fourth modes. In the first and second modes, the first and fourth feeds convey signals at the same frequency using a multiple-input and multiple-output scheme while the second and third feeds are inactive. In the third mode, the second feed is active and the first, third, and fourth feeds are inactive. In the fourth mode, the third feed is active and the first, second, and fourth antenna feeds are inactive. Isolating return paths may be coupled between the segment and ground in the first and second modes.

Abstract: An electronic device may include a housing and four antennas at respective corners of the housing. Cellular telephone transceiver circuitry may concurrently convey signals at one or more of the same frequencies over one or more of the four antennas using a multiple-input multiple-output (MIMO) scheme. In order to isolate adjacent antennas, dielectric-filled openings may be formed in conductive walls of the housing to divide the walls into segments that are used to form resonating element arms for the antennas. If desired, first and second antennas may include resonating element arms formed from a wall without any gaps. The first and second antennas may include adjacent return paths. A magnetic field associated with currents for the first antenna may cancel out with a magnetic field associated with currents for the second antenna at the adjacent return paths, thereby serving to electromagnetically isolate the first and second antennas.

Abstract: An electronic device may have wireless circuitry with antennas. An antenna resonating element arm for an antenna may be formed from conductive housing structures running along the edges of a device. The antenna may have a pair of switchable return paths that bridge a slot between the antenna resonating element and an antenna ground. An adjustable component and a feed may be coupled in parallel across the slot. The adjustable component may switch a capacitor into use or out of use and the return paths may be selectively opened and closed to compensate for antenna loading due to the presence of external objects near the electronic device.

Abstract: An electronic device may be provided with shared antenna structures that can be used to form both a near-field-communications antenna such as a loop antenna and a non-near-field communications antenna such as an inverted-F antenna. The antenna structures may include conductive structures such as metal traces on printed circuits or other dielectric substrates, internal metal housing structures, or other conductive electronic device housing structures. A main resonating element arm may be separated from an antenna ground by an opening. A non-near-field communications antenna return path and antenna feed path may span the opening. A balun may have first and second electromagnetically coupled inductors. The second inductor may have terminals coupled across differential signal terminals in a near-field communications transceiver. The first inductor may form part of the near-field communications loop antenna.