| 摘要 |
1,079,190. Aerials. C.S.F. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Oct. 20, 1965 [Oct. 22, 1964], No. 44523/65. Heading H4A. In a transmitting aerial installation, such as may be used for ultra-high frequency television broadcasting, comprising an aerial system which is mounted in a dielectric radome, a plurality of separate partially reflecting elements is provided, positioned between the aerial system and the radome and spaced approximately onequarter of a wavelength from the latter, whereby nett reflections of energy back into the aerial system are made substantially zero. As described, a cylindrical radome 3, Fig. 3, surrounds radiating elements 1 placed in front of reflectors 2. A partly reflecting element 5 placed in front of a radiating element 1, and approximately a quarter wavelength from the radome 3, transmits the greater part of the output from the element 1, but returns sufficient in such phase as to compensate for energy reflected back from the radome 3. Both the element 5 and the radome 3 may be made of polyester resin reinforced with glass fibres. The element 5 may be flat, as shown in Fig. 3, and thicker than the radome 3, or it may be bent or angled (Fig. 6, not shown). Alternatively, a partly reflecting element may comprise a number of closely spaced metal bars or tubes (6), Fig. 4 (not shown), forming a " synthetic dielectric " element which is placed between the radiating element (1) and the radome (3), with the longitudinal axes of the bars or tubes (6) parallel to the magnetic vector of the radiation. The bars or tubes may form a flat grid (Fig. 5, not shown), or may form a curved grid (Fig. 7, not shown), their spacings may be made non-uniform in accordance with the directivity of the aerial unit (Fig. 8, not shown), and more than one row may be used (Fig. 9, not shown). |
