Abstract: A scanning apparatus operable in the microwave, mm-wave, sub mm-wave (Terahertz) and infrared ranges comprises a primary drum (10) mounted for rotation about a central axis A of the primary drum being hollow and of rectangular polygonal form to provide a number of sides or facets (12, 14) each adapted to transmit such radiation, from a field of view, which is plane polarized in a first direction at 45° with respect to the rotary axis of the drum and to reflect radiation which is plane polarized in an orthogonal direction. Thus, radiation passing into the drum though whichever said side of the drum is currently facing the field of view and passing towards the diametrically opposite side will be plane polarized with a polarization direction such as to be reflected back by that diametrically opposite side towards the rotary axis of the drum.

Abstract: A scanning apparatus operable in the microwave, mm-wave, sub mm-wave (TeraHerz) and infrared ranges comprises a primary drum (10) mounted for rotation about a central axis A of the primary drum being hollow and of rectangular polygonal form to provide a number of sides or facets (12, 14) each adapted to transmit such radiation, from a field of view, which is plane polarised in a first direction at 45° with respect to the rotary axis of the drum and to reflect radiation which is plane polarised in an orthogonal direction. Thus, radiation passing into the drum though whichever said side of the drum is currently facing the field of view and passing towards the diametrically opposite side will be plane polarised with a polarisation direction such as to be reflected back by that diametrically opposite side towards the rotary axis of the drum.

Abstract: An upconverter receives an intermediate frequency (IF) modulated signal on a port (5) and a local oscillator carrier signal at a port (6). A comb generator (13-15) generates a comb-like waveform from the carrier signal, the waveform having a peak for each of a number of multiples of the carrier fundamental. A bandpass filter (16) selects one of the comb peaks and there is further multiplication at a quadrupler (20). The modulated signal (IF) and the multiplied carrier are mixed in a mixer (23) to provide a high frequency upper sideband (LO+IF) output. The output is transmitted in a waveguide (7) which is integral with the casing (2, 3) and which performs high frequency filtering by virtue of its shape.

Abstract: Imaging apparatus is disclosed for passive microwave, millimetre wave, sub-millimetre wave or infrared imaging, the apparatus including a receiver (10) for receiving radiation from the scene or subject being imaged, means for directing such radiation onto the receiver, a cold source (16) or a hot source (16), i.e. a source with a low or high black body temperature, and means (14, 14a) for directing the image or shadow of said cold source or hot source onto the scene or subject being imaged. The result is to produce improved contrast in the image obtained.

Abstract: Scanning apparatus operable in the microwave, mm-wave and infrared ranges and comprises a support structure, a first reflective disc or mirror (10) which is mounted in said support structure for rotation relative to the support structure about a first axis (14), and a second reflective disc or mirror (12) which is mounted in said support structure for rotation relative to the support structure about a second axis (16) and driving means for said discs or mirrors arranged to drive these in respective opposite senses. In operation of the apparatus, radiation from a scene being scanned reaching a reflective surface of the first disc or mirror is reflected thereby onto a reflective surface of the second disc or mirror, to be reflected by the latter, in turn, onto the reflective surface of the first disc or mirror again, to be reflected from the first disc or mirror into or onto a further part of the apparatus incorporating a receiver or receivers for such radiation.

Abstract: Scanning apparatus operable for radiaton comprises a hollow polygonal primary drum rotatable about a central axis to present a plurality of internally presented sides or facets capable of reflecting the radiation concerned. A fixed Mangin mirror mounted within the primary drum directs such radiation onto the internally presented sides or facets of the primary drum to be reflected therefrom onto a rotating reflective faceted secondary drum. The secondary drum reflects the radiation onto a radiation receiver or sensor. The secondary drum is arranged to be rotated about an axis parallel with the rotary axis of the primary drum, in synchronism with the latter, in such a way that, over each line scanning period, radiation from substantially all of the respective facet of the primary drum can reach the receiver or sensor via the secondary drum.