Single feed, multi-element antenna
AssigneeBAE Systems Information and Electronic Systems Integration Inc.
InventorJohn T. Apostolos
Life of this patent
Estimating the term…
Abstract
An array antenna capable of use with a single signal feed has a transmission line oriented substantially parallel to a ground plane, which transmission line has a multiplicity of sequential sections with each sequential section having a different spacing from the ground plane than each of its immediately adjacent sequential sections. This stepped or varied impedance transmission line forms an array in which the sections spaced further from the ground plane become active antenna elements. Controlling an electrical spacing between the ground plane and transmission line provides relative phase control between the active elements and thereby phased-array directional control of the antenna.
Claims19
A varied impedance transmission line antenna, comprising:
- a ground plane;
- a transmission line oriented substantially parallel to said ground plane, said transmission line having a plurality of sequentially stepped sections, wherein said sequentially stepped sections are comprised of alternating high impedance planar sections and low impedance planar sections, said high impedance planar sections at a different spacing from said ground plane than said low impedance planar sections;
- a plurality of interconnect sections serially interconnecting said high impedance planar sections and said low impedance planar sections;
- and a means for varying a spacing between said sequentially stepped sections and said ground plane, wherein said means for varying changes a propagation constant (β) of said transmission line antenna by changing an impedance ratio (ZH/ZL) of said stepped sections according to (β=β0 (½) (sqrt(ZH/ZL)), where ZH is impedance of the high impedance planar sections and ZL is impedance of the low impedance planar sections, and β0 is propagation constant for a similar transmission line of constant impedance.
A varied impedance transmission line antenna, comprising:
- a ground plane;
- a transmission line oriented substantially parallel to said ground plane, said transmission line having a plurality of sequentially stepped sections, wherein said sequentially stepped sections are comprised of alternating high impedance planar sections and low impedance planar sections, said high impedance planar sections at a different spacing from said ground plane than said low impedance planar sections;
- a plurality of interconnect sections serially interconnecting said high impedance planar sections and said low impedance planar sections;
- and
- a dielectric medium disposed between said ground plane and said transmission line;
- and
- a ground plane, wherein said ground plane is moveable and varies a spacing between said transmission line and said ground plane, wherein varying said spacing changes a propagation constant (β) of said transmission line antenna by changing an impedance ratio (ZH/ZL) of said stepped sections according to (β=β0 (½)(sqrt(ZH/ZL)), where ZH is impedance of the high impedance planar sections and ZL is impedance of the low impedance planar sections, and β0 is propagation constant for a similar transmission line of constant impedance.
Dependencies are inferred from the claim text.