GB1247255A - Improvements in antennas - Google Patents

Abstract

1,247,255. Aerials. THOMSON-CSF. 17 Dec., 1969 [18 Dec., 1968], No. 61494/69. Heading H4A. An aerial comprises a primary source 1, Fig. 1, and a reflecting assembly 2 which is formed from a plurality of adjacent elementary re-radiating sources 3. Each of said sources 3 has at least two independent radiation diagrams, one of which (D 1 ) is orientated in the direction of the primary source 1, and another of which (D 2 ) corresponds angularly with the space zone to be scanned by the aerial. Said scanning is effected by means of variable phase shifting means associated with each source 3. In a first embodiment, each re-radiating source comprises two suitably aligned directional elements placed behind an electromagnetic lens (Fig. 2, not shown). In a second embodiment, each source comprises a plurality of elements which are grouped by a Butler type matrix (Fig. 3, not shown). In a third embodiment, each source is formed by a horn 4, Fig. 4, which tapers to a square waveguide terminated by an orthogonal polarization transition including a phase-shifting means 5. A prism formed from conductive triangular plates 8 is arranged at the mouth of the horn 4. Said prism diverts the beam (D 1 ) which is polarized parallel to the plates 8, whilst not affecting the beam (D 2 ) which is polarized perpendicularly to the said plates. In a fourth embodiment, each source 3, Fig. 5, consists of three pairs of crossed dipoles 4. The horizontal dipoles on the one hand, and the vertical dipoles on the other hand, are connected to respective common points by microstrip lines of appropriate lengths, to obtain suitable phase differences between said dipoles The two common points are connected by a variable phase-shifting means (Fig. 6, not shown).