General Electric Company

The Marconi Company Limited

Edmund W Woloszczuk

Richard G Wash

An antenna formed by an array of dipole elements fed by a triplate or stripline system is provided with earthed posts between the dipoles. These posts prevent radiation from one dipole being received by others thereby improving the antenna efficiency.

Dipole arrays

An antenna capable of producing circularly polarized radiation is formed by two non-coaxial cross dipoles.

Antenna

A triplate fed slot antenna in which a conductive sheet has a slot with a length of .lambda., where .lambda. is the wavelength of a signal intended to be radiated from or received by the antenna. A triplate feed structure is coupled for feeding the slot. The triplate feed structure includes two outer conductors defining walls of a resonant cavity backing the slot, and an inner conductor disposed in the cavity.

Slot antenna

An antenna includes an array of electrically conductive cells each having one open side and containing a radiating/receiving element. The conductive cells reduce mutual coupling between elements.

An antenna arrangement consists of a dipole radiator which is fed via a Triplate three-layer transmission line. The dipole is arranged to radiate and receive plane polarized electro-magnetic radiation having a plane of polarization which is determined by the orientation of an elongate slot in the dipole radiator. The Triplate is coupled to the dipole so as to maintain a substantially constant impedance over a reasonably wide bandwidth. A large number of similar dipole radiators can be mounted side by side and fed from a common Triplate structure and in this latter case a common reflector is used for all dipoles and is mounted on the Triplate structure itself.

Slotted dipole with three layer transmission line feed

The invention is concerned with the provision of a dipole radiator for feeding a parabolic reflector and provides a half wave dipole arranged at the mouth of a shallow cavity. The cavity is preferably circular with a diameter approximately three times its depth. In an example of linearly polarised radiator a cylindrical cavity is provided having a diameter of 0.72.lambda. and a height of 0.26.lambda. and the half wave dipole element is positioned 0.26.lambda. above the base of the cavity so that the dipole element extends beyond the cavity. In an example of circularly polarised radiator two crossed half wave dipole elements are provided, one of which is arranged to be inductive and the other of which is arranged to be capacitive. The cylindrical cavity has a diameter of 0.66.lambda. and a height of 0.28.lambda. and the crossed dipole elements are positioned 0.22.lambda. above the base of the cavity so as to lie flush with the mouth of the cavity.

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Essex, United Kingdom

Edmund W Woloszczuk