| 摘要 |
<p>A millimetre wave antenna (1) is formed by a planar array (2) of millimetre wave radiating elements (3), a substrate (4) carrying the planar array (3), and a ground plane (5) spaced from the planar array (2). The substrate (4) is formed of an infra-red transmissive material and the ground plane (5) is transmissive for infra-red radiation. This enables infra-red radiation to be transmitted via the antenna so facilitating the use of the antenna (1) in apparatus for detecting both millimetre wave and infra-red radiation. The ground plane (5) may comprise a copper mesh (5a) or an imperforate electrically conductive layer of indium tin oxide. The substrate may comprise polyethylene, polypropylene, magnesium fluoride, calcium fluoride, zinc sulphide, zinc selenide or calcium aluminate. <IMAGE></p> |
