GB502302A - Transmitting arrangements for radio direction finding systems - Google Patents

Abstract

502,302. Directive wireless systems. LORENZ AKT.-GES., C. May 24, 1938, No. 15476. Convention date, May 25, 1937. [Class 40 (v)] In a radio beacon transmitter, a plurality of differently-directed course-lines are alternately radiated from a continuously-fed dipole aerial by means of a number of alternately effective and ineffective reflector systems each comprising a plurality of reflecting means. In Fig. 3, the two sets of reflectors R1, R2 and R1<1>, R21 combine with the radiating dipole D to produce the radiation characteristics A1, A2, and All, A2<1> which mark the course lines LI, L2 and L1<1>, L2<1>. The two systems are alternately operative for periods of one minute and are distinguished by their wave, modulation, or keying frequencies. The signals are separated in the receiver by tuned high or low frequency filters, or by acoustical comparison, respectively. A cam-controlled switch may be used conjointly for supplying the characteristic frequency to a given system and for rendering the remaining systems inoperative. The individual reflectors of an inoperative reflector system need not be inoperative, but may assist the operative reflector system in producing the desired radiation characteristic. Keying noises are eliminated by making the circular radiation characteristic of the dipole intersect all points of intersection between the directional characteristics. The angles between the course lines may be varied by suitably adjusting the phases of the reflectors and in cases where a zigzag route is necessary beacon transmitters may be situated at the points of alteration of direction.