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 ground structures and peripheral conductive housing structures defining opposing edges of a slot element. A monopole element may overlap the slot element. The monopole element may be directly fed radio-frequency signals by an antenna feed coupled to the monopole element. The monopole element may radiate the radio-frequency signals in a first frequency band while indirectly feeding the radio-frequency signals to the slot element via near-field electromagnetic coupling. The slot element may radiate the radio-frequency signals in a second frequency band that is lower than the first frequency band. The monopole element and the slot element may collectively form a multi-band antenna that exhibits a relatively wide bandwidth.

Abstract: An electronic device may include ground structures and peripheral conductive housing structures defining opposing edges of a slot element. A monopole element may overlap the slot element. The monopole element may be directly fed radio-frequency signals by an antenna feed coupled to the monopole element. The monopole element may radiate the radio-frequency signals in a first frequency band while indirectly feeding the radio-frequency signals to the slot element via near-field electromagnetic coupling. The slot element may radiate the radio-frequency signals in a second frequency band that is lower than the first frequency band. The monopole element and the slot element may collectively form a multi-band antenna that exhibits a relatively wide bandwidth.

Abstract: An electronic device may include an antenna and peripheral conductive housing structures. A dielectric gap may divide the peripheral conductive housing structures into first and second segments. The first and second segments may be separated from the antenna ground by respective first and second slots and may be fed using respective first and second feeds. An antenna isolation element may be coupled to the antenna ground and may separate the first slot element from the second slot element. The antenna isolation element may include a metal strip having an end coupled to the antenna ground and an opposing tip that extends into the dielectric gap. The antenna isolation element may electromagnetically isolate first radio-frequency signals conveyed by the first antenna feed in a cellular midband from second radio-frequency signals conveyed by the second antenna feed in a cellular high band.

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 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. The peripheral conductive structures may form housing sidewalls. A slot may be machined into a metal housing that separates the housing sidewalls from a planar rear housing portion that forms a ground for an antenna. The slot may be filled with plastic filler. A parasitic antenna resonating element arm that supports an antenna resonance at high band frequencies may be embedded within the plastic filler. The parasitic antenna resonating element may be formed from a portion of the planar rear housing portion.

Abstract: An electronic device may be provided with wireless circuitry that includes a radio-frequency transceiver circuit and an antenna. The antenna may be a patch antenna formed from a patch antenna resonating element and an antenna ground. The patch antenna resonating element may be formed from a metal patch on a printed circuit board. The antenna ground may be formed from a metal housing having a planar rear wall that lies in a plane parallel to the metal patch. The radio-frequency transceiver circuit may be coupled to the metal patch through traces on the printed circuit and may be coupled to rear wall of the housing through a screw and a screw boss in the housing. Buttons and other electrical components may be mounted on the printed circuit board and may be coupled to control circuitry on the printed circuit board through the metal patch.

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 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: 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 a dual arm inverted-F antenna. The antenna may have a resonating element formed from portions of a peripheral conductive electronic device housing member and may have an antenna ground that is separated from the antenna resonating element by a gap. A short circuit path may bridge the gap. An antenna feed may be coupled across the gap in parallel with the short circuit path. Low band tuning may be provided using an adjustable inductor that bridges the gap. The antenna may have a slot-based parasitic antenna resonating element with a slot formed between portions of the peripheral conductive electronic device housing member and the antenna ground. An adjustable capacitor may bridge the slot to provide high band tuning.

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 include a peripheral conductive housing wall. The housing wall may be patterned to form first and second continuous regions defining opposing edges of a patterned region. The patterned region may include slots that divide the wall into conductive structures between the first and second continuous regions. A tuning element for an antenna in the device may be formed from the conductive structures and the slots in the patterned region. The slots and the conductive structures in the patterned region may be configured to mitigate any excessive capacitances between the first and second continuous regions in one or more desired frequency bands to optimize antenna efficiency. The slots may be narrow enough so as to be invisible to the un-aided human eye. This may configure the first and second continuous regions to appear to a user as a single continuous piece of conductor.

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 include a peripheral conductive housing wall. The housing wall may be patterned to form first and second continuous regions defining opposing edges of a patterned region. The patterned region may include slots that divide the wall into conductive structures between the first and second continuous regions. A tuning element for an antenna in the device may be formed from the conductive structures and the slots in the patterned region. The slots and the conductive structures in the patterned region may be configured to mitigate any excessive capacitances between the first and second continuous regions in one or more desired frequency bands to optimize antenna efficiency. The slots may be narrow enough so as to be invisible to the un-aided human eye. This may configure the first and second continuous regions to appear to a user as a single continuous piece of conductor.