GB532107A - Improvements in or relating to antennae for radio signalling systems - Google Patents

Abstract

532,107. Directive wireless signalling. THIEMANN, W. H. A. (Bendix Aviation Corporation). May 25, 1939, No. 15598. [Class 40 (v)] An aerial for use with a horizontally-polarised "blind landing" beam consists of a centre-fed dipole with the two limbs 10, 11 bent back in the form of a loop, as shown in plan in Fig. 4. This provides a capacity " loading " and gives the aerial a substantially non-directional response, making it uniformally sensitive even when the plane is diving to land, or heading against a cross-wind. The aerial is fed at adjustable points 20a, 20b by a transmission line 19. The bentback limbs are adjustably secured in a common insulator sleeve 15, which is carried by a support 17, Fig. 5, mounted horizontally on the aeroplane. The aerial is preferably half a wave long, but a sliding bridge 12 near the feeding point allows the length to be adjusted. Figs. 6 and 7 show an alternative construction in which the two limbs 30, 31 are separated vertically, the inner ends 30a, 31a, being brought to a common intermediate plane and bridge at 32. The outer ends 30c and 31c overlap each other, as shown in elevation in Fig. 7, and are supported by bars 33, 33a and insulating pieces 34. The capacity loading between the overlapping parts allows the overall length of the aerial to be reduced for a given wavelength.