Abstract:
An optical to radio frequency detector comprising an optical guide (11 to 14) for receiving two optical signal components having frequencies that differ by an amount corresponding to a radio frequency, and a radio signal guide (15, 16) coupled with an interaction zone (14) of the optical guide for propagating a radio signal from the interaction zone at the radio frequency. The interaction zone (14) of the optical guide comprises an interaction material presenting a second-order non-linear optical polarisation characteristic to the propagation of the optical signal components, and the radio signal guide (15, 16) is in travelling-wave coupling with the interaction zone. The interaction material includes electrically orientated diazobenzene. The radio signal guide (15, 16) comprises an electrically conductive strip (15) juxtaposed with and extending along the interaction zone (14) on one side thereof and an electrically conductive ground plane (16) juxtaposed with and extending along the interaction zone (14) on an opposite side thereof.
Abstract:
A wireless transmitter includes a stream parser for generating a plurality of spatial streams from a digital signal and a space time block coder (STBC) for mapping each of the spatial streams to a plurality of space-time streams that each include data and a preamble for estimating a channel transfer function. The transmitter also includes a spatial mapper for spatially expanding each of the space-time streams by applying a spatial expansion matrix to data and to first training symbols used in the preamble to probe a channel experienced by the data and by applying an extension matrix to second training symbols used in the preamble to probe at least one additional dimension of the channel to enable use of beamforming to achieve range extension The spatial expansion matrix and the extension matrix form an overall matrix that has at least two orthogonal columns with different norms. The wireless transmitter also includes an analog front end for modulating the spatially expanded space-time streams onto a wireless carrier.
Abstract:
An ultra wide band (UWB) antenna is provided, characterised by a teardrop shaped main conductor 400, wherein beyond a region of attachment, a first derivative of the profile of the main conductor 501 is continuous.
Abstract:
A detector or a modulator for converting between optical and radio frequency signals comprising an optical guide (11 to 14) for propagating two optical signal components having frequencies that differ by an amount corresponding to a radio frequency and a microstrip radio signal guide (15, 16) for propagating a radio signal at the radio frequency, the microstrip radio signal guide being in travelling-wave coupling with an interaction zone (14) of the optical guide comprising material in which interaction between the optical signal components and the radio signal occurs. The microstrip radio signal guide element (15, 16) comprises an electrically conductive strip (15) juxtaposed with and extending along the interaction zone (14) on one side thereof and an electrically conductive ground plane (16) juxtaposed with and extending along the interaction zone (14) on an opposite side thereof. Transition radio signal guide elements (20, 21) in the form of Vivaldi antennas extending transversely to the microstrip (15) connect the microstrip radio signal guide element (15, 16) with a rectangular section wave-guide (18) and a matched load. Each of the transition radio signal guide elements (20, 21) comprises an opening of progressively varying width formed in the electrically conductive ground plane of the microstrip guide (16). Radio frequency signal resonators (24 to 27) extend the ends of the microstrip (15) and the small ends of the Vivaldi antennas.