GB524360A - Improvements in or relating to directional aerials and aerial systems - Google Patents

Abstract

524,360. Directive wireless aerials. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and BOHM, O. Jan. 28, 1939, No. 2988. [Class 40 (v)] The frequency characteristic of a unidirectional aerial of the progressive-wave type is widened by making each radiator AB, Fig. 2, as a straight wire, several wavelengths long (as distinct from the usual rhombic or inverted-V arrangements) and terminating it by an impedance BC two or three times the value of the surge impedance. The terminating impedances may extend in the direction of propagation as i n Fig. 2, or in any other direction. Alternatively, a termination Zo, equal to the surge impedance, may be arranged in series with a non-radiating or " star " capacity to earth, as shown in Fig. 5. Fig. 6 shows an array of parallel wires, each terminating as described, and fed in parallel. The wires may diverge, as shown at 1, 2, Fig. 9, or cross over each other, Fig. 12 (not shown). Different pairs may be arranged one above the other, or may overlap in the same plane. Earth-wires are preferably laid parallel to the radiators, and the feedline may be zig-zagged to minimize back-radiation.