Electrically short transmission line antenna
AssigneeThe United States of America as represented by the Secretary of the Army
InventorRobert E. Whitman
Life of this patent
Estimating the term…
Abstract
At least one but preferably two shorted transmission line antenna sections, ach comprised of a vertical member shorting a horizontal printed circuit transmission line member to a ground plane with the transmission lines being adjustable in length for tuning by utilization of a flexible braid transmission line member connected between the printed circuit transmission line member and a take-up spindle which is adapted to be rotated and accordingly wind or unwind the braid member thereon. The feed point is at the connection of a pair of fixed capacitors, one of which is connected to ground plane while the other is connected to the take-up spindle.
Claims16
An electrically short electromagnetic wave antenna comprising at least one section of shorted transmission line having a length less than a quarter wavelength of the operating frequency wherein the improvement comprises:
- a metal ground plane;
- a substantially vertical transmission line member terminating at one end in the ground plane;
- a strip transmission line member mounted substantially parallel to the ground plane and terminating at one end in the other end of said vertical transmission line member;
- a flexible transmission line member, also substantially parallel to the ground plane, coupled at one end to the other end of said strip transmission line member;
- a rotatable spindle including an electrical conductive element coupled to the other end of said flexible transmission line member and being adapted to wind a predetermined portion of said flexible transmission line member thereon when rotated to vary the electrical length of the shorted transmission line formed by said above recited transmission line members;
- first and second series connected capacitor means respectively adapted to act as tuning means and impedance matching means, said first capacitor means having one side coupled to the electrical conductive element of said spindle and said second capacitor means having one side coupled to the ground plane;
- and
- input means adapted to be coupled to radio apparatus coupled to the common connection between said first and second capacitor means.
Dependencies are inferred from the claim text.