A steerable beam antenna includes a rotatable drum having a diffraction grating surface, and a waveguide feed including first and second conductive metal bases extending axially along the length of the drum, each of the bases having an inner surface spaced from and opposed to the inner surface of the other base, and a proximal surface spaced from the drum surface by a gap. First and second parallel conductive metal plates extend distally from the first and second bases, respectively, the first and second plates having respective inner surfaces separated by an inter-plate space. First and second dielectric strips are flush-mounted on the inner surfaces of the first and second conductive metal bases, respectively, the first dielectric strip extending longitudinally along the inner surface of the first base, and the second dielectric strip extending longitudinally along the inner surface of the second base, opposite the first dielectric strip.

Surface scattering antennas with lumped elements provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure. In some approaches, the surface scattering antenna is a multi-layer printed circuit board assembly, and the lumped elements are surface-mount components placed on an upper surface of the printed circuit board assembly. In some approaches, the scattering elements are adjusted by adjusting bias voltages for the lumped elements. In some approaches, the lumped elements include diodes or transistors.

An object of the present invention is to provide an antenna device having a wide beam scan range with reduced loss. The antenna device according to one aspect of the present invention includes: a first phase shifter, a second phase shifter, and a third phase shifter; a first connection part that electrically connects between the first phase shifter and the second phase shifter directly in series; a second connection part that electrically connects between the second phase shifter and the third phase shifter directly in series; and a power feed part that feeds electric power to the first phase shifter to the third phase shifter, wherein the first phase shifter and the second phase shifter, and the second phase shifter and the third phase shifter respectively have characteristic impedance being discontinuous with respect to each other at the first connection part and the second connection part.

An embodiment of an antenna includes first and second transmission lines, first antenna elements, and second antenna elements. The first transmission line is configured to guide a first signal such that the first signal has a characteristic of a first value, and the second transmission line is configured to guide a second signal such that the second signal has the same characteristic but of a second value that is different than the first value. The first antenna elements are each disposed adjacent to the first transmission line and are each configured to radiate the first signal in response to a respective first control signal, and the second antenna elements are each disposed adjacent to the second transmission line and are each configured to radiate the second signal in response to a respective second control signal. Such an antenna can have better main-beam and side-lobe characteristics, and a better SIR, than prior antennas.

Surface scattering antennas with lumped elements provide adjustable radiation fields by adjustably coupling scattering elements along a waveguide. In some approaches, the scattering elements include slots in an upper surface of the waveguide, and the lumped elements are configured to span the slots provide adjustable loading. In some approaches, the scattering elements are adjusted by adjusting bias voltages for the lumped elements. In some approaches, the lumped elements include diodes or transistors.

A method and apparatus for electronically steering an antenna system is provided. A surface wave is propagated along each of a number of surface wave channels formed in each of a plurality of radiating elements to form a radiation pattern. Each surface wave channel in the number of surface wave channels formed in each radiating element in the plurality of radiating elements is coupled to a transmission line configured to carry a radio frequency signal using a surface wave feed in a plurality of surface wave feed associated with the plurality of radiating elements. A main lobe of the radiation pattern is electronically steered by controlling voltages applied to a plurality of switch elements connecting a plurality of impedance elements in each of the number of surface wave channels.

A radio frequency (RF) circuit is provided for use with a magnetic resonance imaging (MRI) scanner to transmit an RF receive signal to an amplifier circuit, the RF circuit comprising: a transmission line; an antenna electrically connected to a first end portion of the transmission line; an impedance transformation circuit; an impedance matching and detuning circuit electrically connected between the transmission line and the impedance transformation circuit, wherein the impedance matching and detuning circuit includes: multiple reactive impedance elements; and two or more switches operable to controllably switch between configuring the multiple reactive impedance elements to cause matching of overall impedance of the RF circuit to a prescribed input impedance seen at the amplifier circuit at a prescribed RF frequency during a receive mode of the MRI scanner, and to cause an increase of impedance at the antenna, to reduce sensitivity of the antenna to RF signals at the prescribed frequency during an excitation mode of the MRI scanner.

Described embodiments include an antenna system and method. The antenna system includes a surface scattering antenna that has an electromagnetic waveguide structure and a plurality of electromagnetic wave scattering elements. The plurality of electromagnetic wave scattering elements are distributed along the waveguide structure, have a respective activatable electromagnetic response to a propagating electromagnetic wave, and produce a controllable radiation pattern. A gain definition circuit defines a radiation pattern configured to acquire a possible interfering signal. The defined antenna radiation pattern has a field of view covering at least a portion of an undesired field of view of an associated antenna. An antenna controller establishes the defined radiation pattern in the surface scattering antenna by activating the respective electromagnetic response of selected electromagnetic wave scattering elements. A correction circuit reduces an influence of the received possible interfering signal in a contemporaneously received signal by the associated antenna.

A dielectric travelling wave antenna (DTWA) using a TEM mode transmission line and variable dielectric substrate.

An electronically-controlled steerable beam antenna with suppressed parasitic scattering includes a feed line defining an axis x; and first and second arrays of electronically-controlled switchable scatters distributed along the axis x, each of the scatterers in the first and second arrays being switchable between a high state and a low state to scatter an electromagnetic wave propagating through the transmission line so as to form a steerable antenna beam. Each of the scatters of the second array is configured to be 180-phase-shifted relative to a corresponding scatter of the first array. The switchable scatterers of the first and second arrays are configured into high states and low states relative to each other so as to suppress parasitic scattering of the electromagnetic wave without suppressing the steerable antenna beam.