DIELECTRIC TRAVELLING WAVEGUIDE WITH VARACTORS TO CONTROL BEAM DIRECTION
A waveguide formed of two or more dielectric control layers. A varactor layer provides control over the propagation constant, in turn permitting the waveguide to act as a steerable antenna having a controllable beam direction.
1 . An apparatus comprising:
a dielectric waveguide formed of at least a first layer and a second layer;
a varactor coupled to the first and second layers; and
a control circuit coupled to control a voltage applied to the varactor.
2 . The apparatus of claim 1 where a third layer is disposed between the first and second layers, and the third layer comprises a plurality of alternating sections formed of dielectric material with different propagation constants, with a selected subset of the sections providing two or more varactors.
3 . The apparatus of claim 1 where the waveguide is used as a feed for a plurality of antenna elements.
4 . The apparatus of claim 1 where the varactor is formed from a reverse biased PN junction.
5 . The apparatus of claim 1 where the varactor further comprises:
an elongated element having a rectangular cross section composed of a semiconductor material and having a top face and a bottom face opposide the top face;
a first conductive section disposed adjacent the top face; and
a second conductive section disposed adjacent the bottom face.
6 . The apparatus of claim 2 where a same bias voltage applied to the two or more varactors.
7 . The apparatus of claim 2 where different bias voltages are applied to the two or more varactors.