GB612583A - Improvements in or relating to antenna systems - Google Patents

Abstract

612,583. Aerial coupling arrangements. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 28, 1946, No. 16252. Convention date, Jan. 17, 1945. [Classes 40 (v) and 40 (vii)] In a single antenna system for transmission and reception of the same or closely similar frequencies, two directive aerials are employed which are interconnected to a receiver and transmitter in such a manner as to prevent interaction therebetween. The antenna system comprises two directive elements 1, 3 connected by means of two transmission lines 11, 13 of equal length to junctions 15, 17. A pair of branch lines 19, 21 also of equal length connect the points 15, 17 to a common feed point 23 for a radio device 27 (e.g. receiver). The junctions 15, 17 are also connected through lines 31, 33 of equal length to a line balance converter 29, connected by a common feed line 41 to a radio device 43 (e.g. transmitter). Energy from the transmitter 43 flows in the line 31, 180 degrees out of phase with that in the line 33 and the net voltage at the point 23 is nil so that no energy reaches the receiver 27. During reception currents flow down the lines 11, 13 in phase, add at the point 23 and flow to the receiver 27. The transmitter 43, however, is not affected since these in-phase voltages oppose each other in the converter 29. The directive elements 1, 3 are disposed with their directive axes 9 parallel with each other and their centres are displaced one quarter wavelength from each other along the direction of these axes so that a maximum signal may be obtained along the axes 9.