GB945859A - Improvements in or relating to anti-fading aerial systems - Google Patents

Abstract

945,859. Aerials. MARCONI CO. Ltd. Dec. 12, 1961 [May 8, 1961], No. 16704/61. Heading H4A. A V.H.F. aerial system comprises at least two reflector elements and a primary radiating element from which said reflectors are spaced by different distances in the direction of, or in a direction parallel to, the direction of maximum gain of the primary element, the reflectors being so positioned, shaped and dimensioned that if the system is transmitting they share equally the energy transmitted and reflect it in a common direction, while if the system is receiving, they receive energy from the common direction and reflect it in substantially equal amounts to the primary element. Preferably, the primary element has its axis directed upwards towards two tilted reflectors. In one such arrangement (Fig. 1) each reflector 2, 3 is planar and is arranged at 45 degrees to the transmission axis. The reflectors are laterally displaced with respect to each other as shown. In an alternative embodiment (Fig. 2, not shown) one of the reflectors is an annulus. The complement of this arrangement is also described (Fig. 3, not shown). In a further embodiment (Fig. 4, not shown) the lower reflector is a semi-transparent mirror, for example a grid of parallel metal rods or a perforated metal plate or a dielectric sheet. The spacing between the reflectors is adjustable is in all cases adjustable.