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: 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: A circularly polarized electromagnetic-wave radiator, formed from a rectangular section waveguide and a dipole, is energized directly by the guide and placed in the extension of its largest faces. An associated reflector element enables coincidence of the two respective phase centers of the guide and the dipole.

Abstract: A two-band multimode microwave source for an antenna of a low-elevation-tracking radar comprises a higher-frequency section nested in a lower-frequency section, the two sections having E-planes perpendicular to each other. The lower-frequency section includes two outer pairs of waveguides separated by a block which convergingly projects beyond their output ends and is bisected by the E-plane of that section. The higher-frequency section includes two inner pairs of waveguides disposed within that block and separated by an obstruction lying in the last-mentioned E-plane. The higher-frequency wave emitted by the inner waveguides is made planar by a lens disposed at n output aperture of the structure which is transparent to the lower-frequency wave.

Abstract: A multimode ultrahigh-frequency source with wide passband comprises a rectangular waveguide with a cavity terminating at an exit aperture in a horizontally flared horn, an input end of the cavity remote from the horn being joined at a transverse discontinuity plane to an upper and a lower pair of symmetrically disposed rectangular supply guides that are vertically separated from each other. An obstruction in the form of a block located between the levels of the supply guides extends from the discontinuity plane forward into the cavity and converges toward the horn in the vertical E-plane, e.g. with a trapezoidal cross-section. With the supply guides excited in the basic TE.sub.10 mode, a suitable dimensioning of the block will maintain a cophasal relationship between this basic mode and a hybrid mode EM.sub.12, originating at the discontinuity plane, in the exit aperture of the cavity over a wide frequency band.

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.

Abstract: An antenna system of the Cassegrain type, used with a tracking radar and adapted to conically scan incoming waves reflected by outlying targets, comprises a paraboloidal main reflector and two hyperboloidal auxiliary reflectors confronting same. One of the auxiliary reflectors is semitransparent and coaxial as well as cofocal with the main reflector whereas the other is solid with an axis inclined to that of the main reflector about which it rotates while keeping its foci in the focal planes of the semitransparent reflector.

Abstract: Disclosed is a radiating source formed by a dipole excited by a flat waveguide which is rectangular in section and is formed by a dielectric sheet having the shape of a rectangular prism whose major and minor faces are each covered with a metal layer of lesser length. The two major faces parallel to the longitudinal midplane are each extended toward the end of the dielectric sheet by means of a metal tongue terminating in one of the stems of the dipole. These stems may be parallel or perpendicular to the direction of polarization of the electric wave radiated by the guide.

Abstract: A mixed E-plane and H-plane multimode monopulse feed is formed by a multimode E-plane horn structure, in the aperture of which metal bars or plates are arranged parallel to the electrical field. The bars or plates form discontinuities at which an odd mode of the H.sub.30 type is generated, the feed as a whole thus becoming a multimode H-plane structure. Such a feed is very useful for the production of multimode monopulse antennas of reduced dimensions.

Abstract: An antenna of the discone type is omnidirectional in bearing and has a diagram whose directivity in elevation can be adjusted. At the apex end of each cone a dielectric disc of predetermined thickness is inserted parallel to the base of the cone concerned. In the central portion of the antenna these two discs create conditions for the propagation of energy which are different from those existing outside the discs, the result being an improvement in the phase pattern in the radiating aperture of the antenna.