| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a mechanically-robust and electrically-stable antenna which is much smaller than an air-core antenna. <P>SOLUTION: An antennal which is utilized for ultra-high sound waves or sound waves higher than those has a cylindrical ceramic core (12) of a relative dielectric constant of at least 5. Spiral antenna elements (10A-10D) on the surface of the core cylinder, connected to radial elements (10AR-10AD) on end surface of the core ends (12D) are formed by conductor tracks plated directly on surface of the core. End surface of the elements are connected to a feeder structure placed axially within a plated axial passage (14) of the core. The antenna elements are connected together by a sleeve (20) that is plated, covering the initial end of the core, which in conjunction with the feeder structure, forms a balun of integral structure for matching with an unbalanced feeder. The core fills most of the interior volume. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
