GB599922A - Improvements in antenna systems - Google Patents

Abstract

5 9 9 , 9 2 2. Directive radio systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. Feb. 9, 1945, No. 3369. Convention date, April 21, 1943. [Class 40 (v)] An antenna system whose direction of maximum radiation may be changed, consists of an array of three spaced radiator elements coupled to a main transmission line by branch transmission lines and has cyclically variable reactance means connected to the two side branch transmission lines. Dipoles 1 and 5 are fed by connecting lines 7, 9 and 19, 21 from junctions 11 and 23 respectively, quarterwavelength branch lines lead from these junctions to the end of the main feeder 33 ; the central aerial 3 is similarly connected to this point by connecting lines 13, 15 and a quarterwavelength branch line 27. Junctions 11 and 23 are also connected by lines 35 and 37 to the stationary plates 41 and 43 of capacitor 39 which is more fully described in Specification '599,383. The moving portion of this capacitor consists of a semicircular plate 45 mounted on coaxial line 42 which has an adjustable shorting plug 44; it may be rotated by motor 51. The lengths of lines 35 and 37 are adjusted so that minimum capacitance is reflected at junction 11 or 23 as a capacitive reactance and maximum capacitance as an inductive reactance, the values of these reactances being made equal by adjusting plug 44. Thus, as capacitor 39 is rotated, the energization of antenna 1 alternately leads and lags and antenna 5 lags and leads on central antenna 3, and alternate overlapping directive radiation patterns are produced.