Antenni

摘要

An antenna for use at UHF and upwards has a cylindrical ceramic core (12) with a relative dielectric constant of at least 5. A three-dimensional radiating element structure, consisting of helical antenna elements (10A - 10D) on the cylindrical surface of the core (12) and connecting radial elements (10AR - 10AD) on a distal end face (12D) of the core, is formed by conductor tracks plated directly on the core surfaces. At the distal end face the elements are connected to an axially located feed structure in a plated axial passage (14) of the core (12). The antenna elements are connected together by a plated sleeve (20) covering a proximal part of the core (12) which, in conjunction with the feeder structure, forms an integral balun for matching to an unbalanced feeder. Since the ceramic core fills the major part of the interior volume defined by the radiating element structure, the antenna is very much smaller than an air-cored antenna. It is also mechanically robust and electrically stable.