GB1022998A - Wide band direction finding system antenna - Google Patents

Abstract

1,022,998. Aerials; radio beacons and direction-finders. CSF.-COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. May 5, 1964 [May 7, 1963; April 28, 1964], No. 18699/64. Headings H4A and H4D. In a radio beacon or direction-finder utilizing two spaced aerial arrays affording overlapping radiation diagrams of the same shape and the same maximum gain, the ratio of the array gain in the equi-signal direction to the maximum gain is maintained substantially constant over a wide frequency range (e.g. 2 : 1) by varying the relative phase shifts between array elements. In an embodiment wherein each array comprises two elements a 1 , a 2 , Fig. 5 (not shown), feeding a receiver (3) via a directional coupler (1), the path from element a 2 includes a phase-shifter (2) and the phase of the a 2 signal at the receiver relative to the a 1 , signal is made to be: ( - 90‹ + k{f - f 0 }) where k is a constant selected such that in the operating frequency range the above expression remains negative, f 0 is the frequency at which the phase shift introduced in signal a 2 is zero and f is signal frequency. In another arrangement, Fig. 6 (not shown), each array comprises n aerials (A 1 . . . A n ) all but the last of which are correspondingly associated with a network (P) introducing a frequencydependent phase shift and a directional coupler (C); in an example, n = 3, networks P 1 , P 2 introduce phase shifts varying from +31‹ to - 31‹ and + 7‹ to - 7‹ respectively over the frequency range 4À3 to 6À9 Gc(s., and C 1 , C 2 are 4À8 dB and 3 dB couplers respectively.