Abstract: The present invention relates to a dual-feed antenna. The invention provides an antenna comprising first and second electromagnetic radiation paths which join to form a common third electromagnetic radiation path, wherein the first path is rotatable with respect to the second path. In this way, two antenna feeds can be directed independently of one another, whilst combining the electromagnetic radiation paths from the antenna feeds then allows a common set of components to be used in signal analysis or generation.

Abstract: The present invention relates to a dual-feed antenna. The invention provides an antenna comprising first and second electromagnetic radiation paths which join to form a common third electromagnetic radiation path, wherein the first path is rotatable with respect to the second path. In this way, two antenna feeds can be directed independently of one another, whilst combining the electromagnetic radiation paths from the antenna feeds then allows a common set of components to be used in signal analysis or generation.

Abstract: A transporter is provided for use in particular with microwave or millimetric wavelength electromagnetic radiation, and includes a retro-reflecting arrangement and a modulating arrangement, in which the modulating arrangement is operable, by a current-induced field, to apply a predetermined type of pattern of modulation to incident microwave or millimetric wavelength electromagnetic radiation passing therethrough, before and/or after the incident radiation is reflected by the retro-reflecting arrangement. When used in combination with an interrofator unit, a particular type or pattern of modulation applied by the transponder may be detected in order to extract information represented in the modulation.

Abstract: A device for changing the divergence of a beam of microwave radiation comprises a ferrite body having an aperture through which the beam passes. Magnetic wires pass both through the body and across the aperture, or a magnetic coil on either side of the aperture, causes a differential phase delay as the beam passes through the aperture which broadens or narrows the beam.

Abstract: A microwave receiving antenna system (30) is described which is used to determine an originating direction of microwave radiation. The system has a birefringement phase plate (34) which splits radiation incident on it into two components which undergo a differential phase delay as they pass through it. The amount of differential phase delay induced varies with angular position around the phase plate (34) from 0 at an angular position of 0° to &lgr; an angular position of 360°. By determining the differential phase delay (assuming a previously existing relationship) the originating direction of the radiation can be determined.

Abstract: A beam steerer for steering a microwave beam comprises a body of magnetic material having an aperture and magnetic coils for applying a gradient of magnetization across the aperture. Tapered slots extending from the magnetic coils towards a central region of the aperture are filled with a material having a lower magnetic permeability than the magnetic material of the body. Lower reluctance paths available through the central region of the aperture allow more magnetic flux from the magnetic coils to penetrate through the central region than would be the case in a body of uniform material composition.

Abstract: An interferometer comprises a non-uniform beam splitter (34) which splits an incoming beam (30) of energy into two beams (36, 38). The two beams (36, 38) are taken from parts of the incoming beam (30) which overlap. The two beams (36, 38) are fed spacially separated energy feeds (44, 46) and then fed to a comparator to produce sum and difference channels (54, 58). The sum and difference channels (54, 58) are guided to a means for detecting a difference in phase (60) between the sum and difference channels (54, 58).