Abstract: In a waveguide (1) having slots (2, 3) perpendicular to the axis of the waveguide, cut out in a narrow wall of the waveguide, there are positioned, on each side of each slot, pairs of metal flat plates (21, 22; 31, 32) symmetrical with respect to the central axis of the slot. These flat plates modify the electrical field at the associated slot and make it possible to excite it, the value of the coupling being set by the adjusting of the size of the flat plates and of their position with respect to the corresponding radiating slot.

Abstract: In a waveguide (1) having slots (2, 3) perpendicular to the axis of the waveguide and cut in a narrow wall of the waveguide, a printed circuit plate (4) is positioned. This plate has patches (5, 7) for coupling with the energy being propagated in the waveguide and microstrip lines (6, 8) connected to the patches to excite the slots (2, 3) with the energy thus tapped. These slot waveguides can be used particularly in array antennas.

Abstract: A microwave primary source with a phase conical scan having a conical horn containing an obstacle which gives rise to a wave that propagates in the TE.sub.21 mode in quadrature with the TE.sub.11 fundamental mode in the opening of the horn; the obstacle is driven in rotation round the axis V of the horn.

Abstract: The apparatus for selectively skimming a layer of pollutant from the surface of a body of water comprises a hull having two lateral parts and a vertical central part, placed between the lateral parts and projecting forwards with respect to the lateral parts. The parts define channels directing a flow of water and pollutant to pollutant-water separators in the hull. The central part carries immersed deflector wings shaped for creating vortices in said water body which decrease divergence of the flow lines in the vicinity of free water level around the hull. Each lateral part cooperates with the central part to define an open water trapping channel which authorizes water flow under a front portion of the lateral part. A front end portion of each lateral part is connected to an immersed part of the central part which is located forward of the stem of the associated lateral part by a vane arranged for deflecting the flow lines of deeper layers downwardly and outwardly away from the central part.

Abstract: A device for exciting a corrugated ultra-high frequency source of revolution operating in two remote frequency bands, decoupled mechanically from the source. The device includes two excitation devices corresponding to the two operating bands, placed perpendicularly to each other, at respective distances from the mouth of the source such that the waves which they emit remain canalized in the Rayleigh zone of each device and provide optimum coupling between these device and the source.

Abstract: Apparatus for selectively removing a layer of light liquid such as oil from a body of water. The apparatus includes a floating hull having two lateral parts and a central part between the lateral parts forming ducts directing a flow of water and light liquid to separator means in the hull. Means are provided on the central part for creating vortices in the water flowing into the ducts which diminish the divergence of the flow at the water surfaces.

Abstract: A radar antenna of the Cassegrain type comprises a paraboloidal principal reflector confronting a hyperboloidal or flat auxiliary reflector of smaller radius directing linearly polarized radiation from a source on their common axis toward the principal reflector along lines passing through the focal point thereof to produce an axially extending outgoing beam whose central part is intercepted by the auxiliary reflector. The latter consists of an array of linear conductors generally parallel to the direction of polarization while the principal reflector is formed by another conductor array generally inclined at 45.degree. to that direction, the latter array being backed by a solid mirror separated therefrom by a distance smaller than a quarter wavelength at the midfrequency of the emitted radiation.