Abstract: A method of transforming input signals received at N input signal ports to output signals for output at M output signal ports includes generating, from the input signals, first intermediate signals for processing by a fast Fourier transform (FFT), with a predefined number of input ports and output ports corresponding to a size of the FFT; applying the FFT to the first intermediate signals to obtain second intermediate signals; and generating the output signals from the second intermediate signals. The input signal ports are non-uniformly distributed with respect to the input ports in a first signal domain of the input ports; and/or the output signal ports are non-uniformly distributed with respect to the output ports in a second signal domain of the output ports. The disclosure further relates to beamforming networks, reconfigurability in beamforming and beam steering, wideband and narrowband multibeam antenna array devices, FFT processors, programs, and storage media.

Abstract: This application relates to a method of performing wireless communications between a hub station and a plurality of user terminals. The method comprises transmitting radio signals to subsets of user terminals among the plurality of user terminals with sets of active beams, wherein the active beams have beam centers that are determined based on locations of the user terminals. The method further comprises, for each of a plurality of radio resource blocks: selecting a subset of user terminals among the plurality of user terminals; for each user terminal among the subset of user terminals, determining a beam center based on a location of the respective user terminal; and transmitting, using the respective radio resource block, radio signals to the user terminals among the selected subset of user terminals, in beams corresponding to the determined beam centers.

Abstract: A beamforming network for use with a plurality of antenna elements arranged in a planar array of linear sub-arrays includes first and second sets of beamforming sub-networks. Each beamforming sub-network in the first set of beamforming sub-networks is associated with a respective one of the linear sub-arrays and is adapted to generate, via the associated linear sub-array, fan beams along respective beam directions in a first set of beam directions. Each beamforming sub-network in the second set of beamforming sub-networks is associated with a respective one of the beam directions in the first set of beam directions. For each beamforming sub-network in the second set of beamforming sub-networks, each of the output port is coupled to an input port of a respective beamforming sub-network in the first set of beamforming sub-networks that corresponds to the associated beam direction. The application further relates to a multibeam antenna comprising such beamforming network.

Abstract: A beamforming network for use with a plurality of antenna elements arranged in a planar array of linear sub-arrays includes first and second sets of beamforming sub-networks. Each beamforming sub-network in the first set of beamforming sub-networks is associated with a respective one of the linear sub-arrays and is adapted to generate, via the associated linear sub-array, fan beams along respective beam directions in a first set of beam directions. Each beamforming sub-network in the second set of beamforming sub-networks is associated with a respective one of the beam directions in the first set of beam directions. For each beamforming sub-network in the second set of beamforming sub-networks, each of the output port is coupled to an input port of a respective beamforming sub-network in the first set of beamforming sub-networks that corresponds to the associated beam direction. The application further relates to a multibeam antenna comprising such beamforming network.

Abstract: A directional waveguide coupler (20) has four input ports and four output ports. Each input port is coupled to each of the output ports. The directional coupler (20) includes a first coupler having two waveguides (W1, W2) coupled to each other by a first slot array (S1), defined in a first wall (21) common to the two waveguides (W1, W2) of the first coupler. A second coupler has two waveguides (W3, W4), coupled to each other by a second slot array (S2), defined in a second wall (22) common to the two waveguides (W3, W4) of the second coupler. The first and second slot arrays (S1, S2) lie on a first common plane. The first and second couplers are coupled to each other by a third slot array (S3) and a fourth slot array (S4), which lie on a second common plane perpendicular to the first common plane.

Abstract: A directional waveguide coupler (20) has four input ports and four output ports. Each input port is coupled to each of the output ports. The directional coupler (20) includes a first coupler having two waveguides (W1, W2) coupled to each other by a first slot array (S1), defined in a first wall (21) common to the two waveguides (W1, W2) of the first coupler. A second coupler has two waveguides (W3, W4), coupled to each other by a second slot array (S2), defined in a second wall (22) common to the two waveguides (W3, W4) of the second coupler. The first and second slot arrays (S1, S2) lie on a first common plane. The first and second couplers are coupled to each other by a third slot array (S3) and a fourth slot array (S4), which lie on a second common plane perpendicular to the first common plane.

Abstract: A method of manufacturing an array antenna comprising: a design phase wherein an array layout of said array antenna is synthesized and radiating elements are designed to be arranged according to said array layout; and a phase of physically making said array antenna wherein the radiating elements are arranged according to said array layout.

Abstract: Reconfigurable RF front-end circuit for a multi-beam array fed reflector antenna system having a first plurality of NB input beam signals and a second plurality of NE radiating elements (RE), and method of operating such a front-end circuit. The front-end circuit comprises a reconfigurable beam forming network (LLRBFN), having a set of NB input ports and distributing each input port signal to a plurality of NA output ports with phase and amplitude control, a plurality of NA high power amplifiers (HPA) connected to the plurality of NA output ports of the reconfigurable beam forming network (LLRBFN) and an output network (ONET, OSN), arranged for recombining signals output by the high power amplifiers (HPA) and feeding the recombined signals to the second plurality of NE radiating elements (RE). The high power amplifiers (HPA) are variable bias high power amplifiers (VB-HPA).

Abstract: Reconfigurable RF front-end circuit for a multi-beam array fed reflector antenna system having a first plurality of NB input beam signals and a second plurality of NE radiating elements (RE), and method of operating such a front-end circuit. The front-end circuit comprises a reconfigurable beam forming network (LLRBFN), having a set of NB input ports and distributing each input port signal to a plurality of NA output ports with phase and amplitude control, a plurality of NA high power amplifiers (HPA) connected to the plurality of NA output ports of the reconfigurable beam forming network (LLRBFN) and an output network (ONET, OSN), arranged for recombining signals output by the high power amplifiers (HPA) and feeding the recombined signals to the second plurality of NE radiating elements (RE). The high power amplifiers (HPA) are variable bias high power amplifiers (VB-HPA).

Abstract: A digital beam-forming network for an array antenna having N>1 antenna ports, to be associated to respective antenna elements, and M?1 beam ports (BP), corresponding to respective antenna beams. The digital beam-forming network comprises a plurality of complex weighting elements interconnected through summing nodes. At least one of the complex weighting elements is connected to either two antenna ports, to be associated with respective antenna elements which are arranged symmetrically with respect to the symmetry axis, or two beam ports corresponding to respective antenna beams pointing toward directions which are symmetrical with respect to the symmetry axis, or both. The digital beam forming network can be a part of an array antenna comprising N antenna elements, NS of which are arranged according to an array pattern having a symmetry axis, NS being an even integer different from zero.

Abstract: A method of providing multi-beam coverage of a Region of Interest (ROI) in a multi-beam satellite communication system in which a non-uniform traffic demand density is defined over said Region of Interest, the method including partitioning the Region of Interest into N>1 non-overlapping cells (V1-V10, Vi); and generating N satellite beams, each of the satellite beams providing coverage of a respective cell. The step of partitioning the Region of Interest into N>1 non-overlapping cells is performed in such a way that the traffic demand associated to the cells is substantially uniform. Advantageously, the cells form a Voronoi diagram defined over the Region of Interest, the satellite beams being pointed towards the cells of the Voronoi diagram. A satellite communication system implementing the method is also provided.

Abstract: A digital beam-forming network (DBF) for an array antenna having N>1 antenna ports (EP), to be associated to respective antenna elements (RE), and M?1 beam ports (BP), corresponding to respective antenna beams (AB), said digital beam-forming network comprising a plurality of complex weighting elements (CWE-SE, CWE-SB, CWE-SESB) interconnected through summing nodes (SN); wherein at least one of said complex weighting element is connected to either two antenna ports, to be associated to respective antenna elements which are arranged symmetrically with respect to said symmetry axis, or two beam ports corresponding to respective antenna beams pointing toward directions which are symmetrical with respect to said symmetry axis, or both. An array antenna comprising N antenna elements, NS of which are arranged according to an array pattern having a symmetry axis, NS being an even integer different from zero, and such a digital beam-forming network.

Abstract: A beam-forming network for an emitting array antenna having at least NB input ports connected to respective beam ports of the beam-forming network and at least NOSA>1 output ports, for associating to each output port a linear combination of input signals from respective input ports; a set of at least NOSA lossless single-mode networks, each having an input port connected to a respective output port of multi-beam network and at least NNOSAOSA>1 output ports, for associating to each output port a signal obtained by weighting an input signal from the input port; and a set of at least NNOSA?NNOSAOSA lossless multi-mode networks, each having at least NNOSAOSA NOSANOSA input ports, each one connected to an output port of a respective single-mode network, and at least NENOSA>1 output ports connected to respective antenna ports of the beam-forming network, for associating to each output port a linear combination of input signals from respective input ports.

Abstract: A satellite communication system including a multibeam satellite for generating a plurality of feeder beams and a plurality of user beams over a region of interest, a plurality of spatially-separated gateway stations for providing feeder links to said multibeam satellite via respective feeder beams; and a control for operating said gateway stations and multibeam satellite such that: in nominal conditions, NGW gateway stations exchange data with K user beams, each of the gateway stations allocating a fraction of its bandwidth to each of the user beams; and in case of fading, data are switched from faded to unfaded gateway stations, whereby none of said user terminals experiences service outage. A method of performing satellite communication using the satellite communication system, and a multibeam communication satellite payload for carrying out the method are provided.

Abstract: A beam-forming network for an emitting array antenna having at least NB input ports connected to respective beam ports of the beam-forming network and at least NOSA>1 output ports, for associating to each output port a linear combination of input signals from respective input ports; a set of at least NOSA lossless single-mode networks, each having an input port connected to a respective output port of multi-beam network and at least NNOSAOSA>1 output ports, for associating to each output port a signal obtained by weighting an input signal from the input port; and a set of at least NNOSA?NNOSAOSA lossless multi-mode networks, each having at least NNOSAOSA NOSANOSA input ports, each one connected to an output port of a respective single-mode network, and at least NENOSA>1 output ports connected to respective antenna ports of the beam-forming network, for associating to each output port a linear combination of input signals from respective input ports.

Abstract: A method of manufacturing an array antenna comprising: a design phase wherein an array layout of said array antenna is synthesized and radiating elements are designed to be arranged according to said array layout; and a phase of physically making said array antenna wherein the radiating elements are arranged according to said array layout.

Abstract: A satellite communication system including a multibeam satellite for generating a plurality of feeder beams and a plurality of user beams over a region of interest, a plurality of spatially-separated gateway stations for providing feeder links to said multibeam satellite via respective feeder beams; and a control for operating said gateway stations and multibeam satellite such that: in nominal conditions, NGW gateway stations exchange data with K user beams, each of the gateway stations allocating a fraction of its bandwidth to each of the user beams; and in case of fading, data are switched from faded to unfaded gateway stations, whereby none of said user terminals experiences service outage. A method of performing satellite communication using the satellite communication system, and a multibeam communication satellite payload for carrying out the method are provided.

Abstract: A method of providing multi-beam coverage of a Region of Interest (ROI) in a multi-beam satellite communication system in which a non-uniform traffic demand density is defined over said Region of Interest, the method including partitioning the Region of Interest into N>1 non-overlapping cells (V1-V10, Vi); and generating N satellite beams, each of the satellite beams providing coverage of a respective cell. The step of partitioning the Region of Interest into N>1 non-overlapping cells is performed in such a way that the traffic demand associated to the cells is substantially uniform. Advantageously, the cells form a Voronoi diagram defined over the Region of Interest, the satellite beams being pointed towards the cells of the Voronoi diagram. A satellite communication system implementing the method is also provided.

Abstract: A beam-forming network having: a plurality (NI) of input signal ports (IP); a plurality (NO) of output signal ports (OP); a weighting and interconnecting network (WIN) comprising a plurality of signal dividers (SD), phase and amplitude weighting elements (WE), switches (SW1, SW2) and signal combiners (SC), for associating each input port to output ports through respective weighting units; wherein either input (IP) or output (OP) ports, or both, are partitioned into disjoint equivalence classes (IEC, OEC), at least a majority of said equivalence classes having more than one port; and in that the network is either configured in order to associate each input port to at most one output port for each output equivalence class, or to associate each output port to at most one input port for each input equivalence class, or both. Also provide is a multibeam antenna comprising having such a beam-forming network, and an electronic circuit for implementing such a beam-forming network.

Abstract: A multibeam antenna comprising: a plurality of primary radiating elements, each associated to a respective beam; and an active radiating structure comprising a first planar array of radiating elements, a second planar array composed by a same number of radiating elements, a set of connections between each radiating element of the first planar array and one corresponding element of the second planar array, and a set of power amplifiers for amplifying signals transmitted through said connections; wherein: the relative positions of the radiating elements of the first and second planar arrays and phase delays introduced by said connections are such that the radiating structure forms an active discrete converging lens; and said primary radiating elements are clustered on a focal surface of said lens, facing the first planar array; characterized in that said first and second planar arrays are both aperiodic. A method of manufacturing such an antenna.