Abstract: A retrodirective antenna system (1) for receiving an incoming signal (15) from an object (13) and directing an outgoing signal (11) back to the object (13), comprising two or more transceiver cells (3), each of which receives a part of the incoming signal, produces a phase conjugate output signal, which output signals from the cells combine to form an outgoing signal (11) directed back to the object (13), wherein each transceiver cell (3) comprises an antenna component (7) which detects the part of the incoming signal, a processor which receives the part of the incoming signal and produces first and second same-side, sideband (SB) signals of the part of the incoming signal, a phase shift system comprising a first phase element which receives the first SB signal and outputs a SB signal having a first phase, and a second phase element which receives the second SB signal and outputs a SB signal having a second phase which is in quadrature with the first phase, and an IQ modulator comprising an I input port, a Q

Abstract: A retrodirective antenna system (1) for receiving an incoming signal (15) from an object (13) and directing an outgoing signal (11) back to the object (13), comprising two or more transceiver cells (3), each of which receives a part of the incoming signal, produces a phase conjugate output signal, which output signals from the cells combine to form an outgoing signal (11) directed back to the object (13), wherein each transceiver cell (3) comprises an antenna component (7) which detects the part of the incoming signal, a processor which receives the part of the incoming signal and produces first and second same-side, sideband (SB) signals of the part of the incoming signal, a phase shift system comprising a first phase element which receives the first SB signal and outputs a SB signal having a first phase, and a second phase element which receives the second SB signal and outputs a SB signal having a second phase which is in quadrature with the first phase, and an IQ modulator comprising an I input port, a Q

Abstract: A freestanding frequency selective surface (FSS) is provided which comprises at least one shorted resonance aperture element (12). The shorted resonance aperture element provides a sensitivity to polarization. The shorted resonance aperture element may comprise at least one short, which may enable the FSS to be freestanding. The invention further provides an FSS device comprising at least one array of the freestanding frequency selective surfaces, and a method of forming the freestanding frequency selective surfaces.

Abstract: A freestanding frequency selective surface (FSS) is provided which comprises at least one shorted resonance aperture element (12). The shorted resonance aperture element provides a sensitivity to polarisation. The shorted resonance aperture element may comprise at least one short, which may enable the FSS to be freestanding. The invention further provides an FSS device comprising at least one array of the freestanding frequency selective surfaces, and a method of forming the freestanding frequency selective surfaces.

Abstract: A class E power amplifier circuit comprising an active device, a DC blocking element and an oscillating element, wherein the oscillating element is driven by a voltage signal.

Abstract: Method and apparatus for providing an amplified modulated radio frequency signal, the method comprising the steps of providing a radio frequency (RF) oscillatory signal, generating from the RF oscillatory signal and an input signal a pair of phase modulated phase conjugated signals, and summing the pair of signals to provide the desired modulated RF signal output. A form of the invention is applied to digital modulation using in-phase (I) and quadrature (Q) input signals. Each of the I and Q signals is processed in a respective channel, with the channel outputs being summed. The channels share an RF oscillatory signal, which is phase shifted by 90 degrees within the Q channel.

Abstract: An antenna comprises a polarizer, a phasing network and a field radiating element such as a horn. The polarizer and phasing network generate a plurality of phase shifted circularly polarised waves which are superimposed to produce multiple antenna field patterns from a single antenna aperture.