GB1403769A - Phased array fed lens antenna - Google Patents

Abstract

1403769 Aerials SPERRY RAND CORP 28 Nov 1972 [20 Dec 1971] 54851/72 Heading H4A An electronic scanning system comprises a source of radiant electromagnetic energy, array means including feed elements which are coupled to said source for producing a first beam having a non-planar wavefront, and controllable focal properties, and lens means which are responsive to said first beam and which implement a phase gradient for producing a directive second beam having a plane wavefront, a variable range of scan, and an attendant variable gain. As described, an electronic scanning system 10, Fig. 1, comprises a substantially spherically shaped lens 11 which has a plurality of radiator elements 14 on its exterior coupled by respective phase delay elements 13 to respective ones of a like plurality of collector elements 12 on its interior. An array means 15 is disposed within the lens 11 and comprises a plurality of radiator elements 20, which face towards the collector elements 12, a like plurality of collector elements 16, which face towards a feed horn 21, and a like plurality of electronically controlled phase shifters 17, each of which couples an element 16 to a respective element 20. In operation, spherical wavefronts from the feed horn 21 are converted into by the array means 15 into non- planar wavefronts. These are then converted by the lens 11 into planar wavefronts, which are directed at an angle #<SP>1</SP> to the normal N. The phase delay elements 13 may have fixed values, and a formula is given for their determination in terms of # (the angular displacement from the normal N). The array means 15 may be controlled to produce a converging beam when directed along the normal N towards the lens 11, and to produce a diverging beam when directed away from said normal. In this way, the system may provide a broad beam with low gain in the vertical direction, and narrow, high gain beams in directions near the horizontal (Fig. 11, not shown). The lens may be cylindrical instead of spherical, and the array means may be linear or planar. The radiator and collector elements of the lens may be dipoles, with phase delay elements constituted by lengths of flexible cable (Fig. 7, not shown). Alternatively, the said elements may be open ended circular waveguides with dielectric phase delay coupling elements (Fig. 8, not shown). In another embodiment the lens means is a solid dielectric lens, and may constitute the nose cone of a high speed aircraft, when it could be made of titanium dioxide (Fig. 9, not shown). The exterior is of hyperbolic shape, and the required phase delays may be obtained either by fabricating it from materials of different refractive indices or by variation of its wall thickness from the base to the apex.