GB1359830A - Multimode antennas - Google Patents

Abstract

1359830 Aerials THOMSON-CSF 21 Dec 1971 [22 Dec 1970] 59476/71 Heading H4A A wideband aerial comprises a radiating aperture 17, Fig. 3, at the end of a multimode waveguide 16. The aerial is supplied by at least two waveguides operating in the fundamental mode (as shown there are two such waveguides, 5 and 6). Higher mode generation is effected by at least two successive discontinuities having stepped profiles which increase the crosssectional area in the direction of propagation, such as the steps 13, 14, which are separated by an intermediate waveguide 15. In a second embodiment (Fig. 4, not shown), which is suitable for monopulse working, the intermediate waveguide is flared, and supplementary waveguide feeds are provided at the level of the second discontinuity. Decoupling between the main and supplementary feeds is effected by means of metal plates, disposed transversely of the electric field of the fundamental mode, in the main waveguide. In a third embodiment (Fig. 2, not shown), the main waveguide is flared and, in addition to feed means comprising two primary waveguides and an intermediate waveguide as described above, a third waveguide feeds the main waveguide through a flared intermediate waveguide, with step-like discontinuities at each end thereof. Specifications 1,002,140 and 1,054,057 are mentioned.