GB577460A - Improvements in and relating to radio compasses - Google Patents

Abstract

577,460. Directive wireless signalling. SJOSTRAND, H. E. March 23, 1943, No. 4701. Convention date, March 26, 1942. [Class 40 (v)] [Also in Groups XIX, XXXII and XXXVI] In a direction-finder of the kind in which a directive aerial is continuously rotated in synchronism with an electromagnet receiving signals from the aerial, the electromagnet has poles on each side of the axis of rotation and the armature of the electromagnet is asymmetric about the axis. The armature is connected to the indicating pointer through a spring or other coupling which damps the action of the armature on the pointer so that the influence of night effects, which vary the direction of the received waves, is reduced or avoided. In one form, Fig. 1, a three-pole magnet a, b, c rotates with shaft 1 and its armature 10 on spindle 11 is connected by a spiral spring 18 to a float 16 having fins 17 immersed in liquid and carrying the pointer 15. The spring 18 may be replaced by two spiral springs, the inner ends of which are connected to the armature and the pointer, and the outer ends to a common disc, Fig. 2 (not shown), this arrangement compensating for heat-expansion. The electromagnet may have only two poles, or four or more poles acting on a pair of permanent magnets mounted astatically, Fig. 3 (not shown), or on a horseshoe magnet, Fig. 4 (not shown). The float and damping liquid may be replaced by a magnetic damping device, or the springs may be replaced by a magnetic, pneumatic, or other yielding coupling means, Figs. 5 and 6 (not shown). Specification 475,027 is referred to.