Abstract: A control system is presented for controlling operation of a phased-array antenna comprising N antenna elements each comprising H and V polarization terminals. The control system includes: an analogue circular polarization system (ACTS) and a digital polarization control system (DPCS). The ACPS comprises an array of N analogue circular polarization circuits (ACPCs) associated with said N antenna elements, respectively, such that each ACPC is connectable to the V and H polarization terminals of the respective antenna element. The ACPS is configured and operable with N analog circular polarization signal components each being either left or right circular polarization signal.

Abstract: A control system is presented for controlling operation of a phased-array antenna comprising N antenna elements each comprising H and V polarization terminals. The control system includes: an analogue circular polarization system (ACTS) and a digital polarization control system (DPCS). The ACPS comprises an array of N analogue circular polarization circuits (ACPCs) associated with said N antenna elements, respectively, such that each ACPC is connectable to the V and H polarization terminals of the respective antenna element. The ACPS is configured and operable with N analog circular polarization signal components each being either left or right circular polarization signal.

Abstract: Method of operating under water an antenna device comprising a frequency-tunable circuit, comprising: tuning said circuit between a first frequency and a second frequency for obtaining a variable directional radiation pattern by the antenna device, to select a directional radiation pattern of the antenna device for improving the radio signal coupling between the antenna devices, in particular for maximizing the radio signal coupling between the two antenna devices, wherein said first frequency and a second frequency are predetermined according to the saltwater-freshwater content of the water such that the directional radiation pattern of the antenna device for one of the two frequencies is directional and the directional pattern of the antenna device for the other of the two frequencies is omnidirectional.

Abstract: Method of operating under water an antenna device comprising a frequency-tunable circuit, comprising: tuning said circuit between a first frequency and a second frequency for obtaining a variable directional radiation pattern by the antenna device, to select a directional radiation pattern of the antenna device for improving the radio signal coupling between the antenna devices, in particular for maximizing the radio signal coupling between the two antenna devices, wherein said first frequency and a second frequency are predetermined according to the saltwater-freshwater content of the water such that the directional radiation pattern of the antenna device for one of the two frequencies is directional and the directional pattern of the antenna device for the other of the two frequencies is omnidirectional.