Abstract: Systems and techniques are provided for a spiral light antenna. An antenna element may include a first curved element disposed orthogonally to a second curved element. The first curved element and the second curved element may be connected at a connection point at a center of the first curved element and a center of the second curved element. The antenna element may have rotational symmetry and origin symmetry though the connection point but not linear symmetry. The first curved element may be longer than the second curved element. A feed may be connected to the antenna element at the connection point perpendicular to the plane of the antenna element. The first curved element may be inductive, and the second curved element may be capacitive. The antenna element may be disposed at the front of a light bulb and the feed may extend towards the back of the light bulb.

Abstract: Disclosed are a system and a device including a dipole antenna, signal conductors and a transceiver. The dipole antenna may be enclosed in a housing, and have offset signal connections for transmitting and receiving signals. The signal conductors may be communicatively connected to the offset signal connections. The transceiver may be connected to the signal conductors through a balanced communication signal path. The impedance of the dipole antenna may be substantially gamma matched to the impedance of the balanced communication signal path and an input impedance of the transceiver according to an amount of offset of the signal connections.

Abstract: Slot antennas are provided for electronic devices such as portable electronic devices. The slot antennas may have a dielectric-filled slot that is formed in a ground plane element. The ground plane element may be formed from part of a conductive device housing. The slot may have one or more holes at its ends. The holes may affect the impedance characteristics of the slot antennas so that the length of the slot antennas may be reduced. For example, the holes can be used to synthesize the impedance of the slot antennas so that the slot antennas have a resonant frequency that is different from their natural resonant frequency. The holes may affect the impedance of the slot antennas in multiple radio-frequency bands.

Abstract: Electronic devices may include radio-frequency transceiver circuitry and antenna structures. The antenna structures may include antenna resonating elements such as dual-band antenna resonating elements that resonate in first and second communications bands. The antenna structures may also contain parasitic antenna elements such as elements that are operative in only the first or second communications band and elements that are operative in both the first and second communications bands. The antenna resonating elements and parasitic elements may be mounted on a common dielectric carrier. The dielectric carrier may be mounted within a slot or other opening in a conductive element. The conductive element may be formed from conductive housing structures in an electronic device such as a portable computer. The portable computer may have a clutch barrel with a dielectric cover. The dielectric cover may overlap and cover the slot and the dielectric carrier.

Abstract: Slot antennas are provided for electronic devices such as portable electronic devices. The slot antennas may have a dielectric-filled slot that is formed in a ground plane element. The ground plane element may be formed from part of a conductive device housing. The slot may have one or more holes at its ends. The holes may affect the impedance characteristics of the slot antennas so that the length of the slot antennas may be reduced. For example, the holes can be used to synthesize the impedance of the slot antennas so that the slot antennas have a resonant frequency that is different from their natural resonant frequency. The holes may affect the impedance of the slot antennas in multiple radio-frequency bands.

Abstract: Slot antennas are provided for electronic devices such as portable electronic devices. The slot antennas may have a dielectric-filled slot that is formed in a ground plane element. The ground plane element may be formed from part of a conductive device housing. The slot may have one or more holes at its ends. The holes may affect the impedance characteristics of the slot antennas so that the length of the slot antennas may be reduced. For example, the holes can be used to synthesize the impedance of the slot antennas so that the slot antennas have a resonant frequency that is different from their natural resonant frequency. The holes may affect the impedance of the slot antennas in multiple radio-frequency bands.

Abstract: Antenna window structures and antennas are provided for electronic devices. The electronic devices may be laptop computers or other devices that have conductive housings. Antenna windows can be formed from dielectric members. The dielectric members can have elastomeric properties. An antenna may be mounted inside a conductive housing beneath a dielectric member. The antenna can be formed from a parallel plate waveguide structure. The parallel plate waveguide structure may have a ground plate and a radiator plate and may have dielectric material between the ground and radiator plates. The ground plate can have a primary ground plate portion and a ground strip. The ground strip may reflect radio-frequency signals so that they travel through the dielectric member. The antenna may handle radio-frequency antenna signals in one or more communications bands. The radio-frequency antenna signals pass through the dielectric member.

Abstract: Key antennas are provided for an electronic device such as a laptop computer. The electronic device may have radio-frequency transceivers that transmit and receive signals using the key antennas. An antenna resonating element may be mounted beneath a keycap of each key antenna. The antenna resonating element may be spirally wrapped and integrated into the keycap. The key antenna may function as an antenna and may also function as an input key for an electronic device. A flexible communications path may pass through a hole in a conductive housing of the electronic device and may be used to couple the antenna resonating element to the radio-frequency transceiver. The antenna resonating element may be coupled to the radio-frequency transceiver by a weak spring. The weak spring may form a portion of the antenna resonating element.

Abstract: A removable antenna is provided for an electronic device such as a laptop computer. An antenna resonating element is mounted within the antenna. Magnetic coupling structures are used to magnetically attach the antenna to the electronic device. The magnetic coupling structures couple the antenna resonating element to circuitry in the electronic device. The electronic device may have an antenna receptacle that holds the antenna in a stowed position and allows the antenna to extend to an extended position. A user may extend the antenna by sliding the antenna or by rotating the antenna to its extended position. The coupling structures may allow the antenna to break away from the electronic device without damage.

Abstract: Antenna window structures and antennas are provided for electronic devices. The electronic devices may be laptop computers or other devices that have conductive housings. Antenna windows can be formed from dielectric members. The dielectric members can have elastomeric properties. An antenna may be mounted inside a conductive housing beneath a dielectric member. The antenna can be formed from a parallel plate waveguide structure. The parallel plate waveguide structure may have a ground plate and a radiator plate and may have dielectric material between the ground and radiator plates. The ground plate can have a primary ground plate portion and a ground strip. The ground strip may reflect radio-frequency signals so that they travel through the dielectric member. The antenna may handle radio-frequency antenna signals in one or more communications bands. The radio-frequency antenna signals pass through the dielectric member.

Abstract: Antenna window structures and antennas are provided for electronic devices. The electronic devices may be laptop computers or other devices that have conductive housings. Antenna windows can be formed from dielectric members. The dielectric members can have elastomeric properties. An antenna may be mounted inside a conductive housing beneath a dielectric member. The antenna can be formed from a parallel plate waveguide structure. The parallel plate waveguide structure may have a ground plate and a radiator plate and may have dielectric material between the ground and radiator plates. The ground plate can have a primary ground plate portion and a ground strip. The ground strip may reflect radio-frequency signals so that they travel through the dielectric member. The antenna may handle radio-frequency antenna signals in one or more communications bands. The radio-frequency antenna signals pass through the dielectric member.

Abstract: Electronic devices may be provided with sensors for determining the presence and position of extendable and removable antennas. The antennas may extend by rotating about an axis, by reciprocating along their length, or by flexing from a retracted position to an extended position. The electronic device may determine when a removable antenna is attached or detached using signals from the sensors. The electronic device may determine the extent to which an antenna has been extended using signals from the sensors. The electronic device may control the operation of a radio-frequency transceiver that is coupled to the antenna based on signals from the sensors. The electronic device may turn the transceiver off when the antenna is retracted or removed. When the antenna is partially extended, the electronic device may place the transceiver in a low-power mode or place a dual-band transceiver into a single-band mode.

Abstract: Antenna window structures and antennas are provided for electronic devices. The electronic devices may be laptop computers or other devices that have conductive housings. Antenna windows can be formed from dielectric members. The dielectric members can have elastomeric properties. An antenna may be mounted inside a conductive housing beneath a dielectric member. The antenna can be formed from a parallel plate waveguide structure. The parallel plate waveguide structure may have a ground plate and a radiator plate and may have dielectric material between the ground and radiator plates. The ground plate can have a primary ground plate portion and a ground strip. The ground strip may reflect radio-frequency signals so that they travel through the dielectric member. The antenna may handle radio-frequency antenna signals in one or more communications bands. The radio-frequency antenna signals pass through the dielectric member.

Abstract: Slot antennas are provided for electronic devices such as portable electronic devices. The slot antennas may have a dielectric-filled slot that is formed in a ground plane element. The ground plane element may be formed from part of a conductive device housing. The slot may have one or more holes at its ends. The holes may affect the impedance characteristics of the slot antennas so that the length of the slot antennas may be reduced. For example, the holes can be used to synthesize the impedance of the slot antennas so that the slot antennas have a resonant frequency that is different from their natural resonant frequency. The holes may affect the impedance of the slot antennas in multiple radio-frequency bands.

Abstract: A removable antenna is provided for an electronic device such as a laptop computer. An antenna resonating element is mounted within the antenna. Magnetic coupling structures are used to magnetically attach the antenna to the electronic device. The magnetic coupling structures couple the antenna resonating element to circuitry in the electronic device. The electronic device may have an antenna receptacle that holds the antenna in a stowed position and allows the antenna to extend to an extended position. A user may extend the antenna by sliding the antenna or by rotating the antenna to its extended position. The coupling structures may allow the antenna to break away from the electronic device without damage.

Abstract: Key antennas are provided for an electronic device such as a laptop computer. The electronic device may have radio-frequency transceivers that transmit and receive signals using the key antennas. An antenna resonating element may be mounted beneath a keycap of each key antenna. The antenna resonating element may be spirally wrapped and integrated into the keycap. The key antenna may function as an antenna and may also function as an input key for an electronic device. A flexible communications path may pass through a hole in a conductive housing of the electronic device and may be used to couple the antenna resonating element to the radio-frequency transceiver. The antenna resonating element may be coupled to the radio-frequency transceiver by a weak spring. The weak spring may form a portion of the antenna resonating element.

Abstract: Electronic devices may be provided with sensors for determining the presence and position of extendable and removable antennas. The antennas may extend by rotating about an axis, by reciprocating along their length, or by flexing from a retracted position to an extended position. The electronic device may determine when a removable antenna is attached or detached using signals from the sensors. The electronic device may determine the extent to which an antenna has been extended using signals from the sensors. The electronic device may control the operation of a radio-frequency transceiver that is coupled to the antenna based on signals from the sensors. The electronic device may turn the transceiver off when the antenna is retracted or removed. When the antenna is partially extended, the electronic device may place the transceiver in a low-power mode or place a dual-band transceiver into a single-band mode.