| 摘要 |
1,072,366. Aerials. SIEMENS - SCHUCKERTWERKE A.G. June 29, 1964 [June 28, 1963; April 15, 1964], No. 26879/64. Heading H4A. [Also in Division G2] An arrangement, Fig. 1, comprising a number of short (1 mm. or less) conductive rodlets embedded in substantially parallel formation in a relatively non-conductive rigid carrier substance can transmit deci-millimetric or infra-red electromagnetic (E.M.) waves of frequencies not less than 3 x 10<SP>11</SP> c/s. whose electric vector is perpendicular to the rodlet axes, but will scatter or reflect E.M. waves whose electric vector is parallel to the rodlet axes, said rodlets functioning as electric dipoles. Typical transmission and reflection curves are illustrated in Figs. 2 and 3, respectively (not shown). As described, a molten eutectic of a semi-conductor material with another material which tends to form conductive rodlets on crystallizing is formed and allowed to solidify by a normal freezing process. The parallel orientation of the rodlets may be assisted by, for example, the application of a magnetic field, or by freezing the melt in a flowing condition. Suitable combinations of semi-conductor materials/rodlet materials for such eutectics are indium antimonide/antimony or an antimonide of chromium, iron, manganese or nickel, gallium antimonide/antimony and germanium/cobalt or nickel. In another embodiment, a combination prepared as described above is treated with a solvent which removes the semi-conductor and the recovered rodlets are re-embedded in another carrier substance, such as glass. A transmission filter prepared according to the second embodiment consists of indium antimonide with 1�8 % by weight of nickel antimonide, the latter forming rodlets of diameter about 1 micron (�) and lengths from 10� to 50�. When a reflection filter is required, e.g. for use with a laser, the density of the rodlets in the carrier substance is preferably greater than for a transmission filter, and the material of which they are composed, ferromagnetic. A eutectic of indium antixnonide and mangauese antimonide, containing approximately 6% by weight of the latter may be used. |
