Antenna for underwater radio communications

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. Antenna device arranged to periodically tune said circuit to select a directional radiation pattern of the antenna device for improving the radio signal coupling with another antenna device, in particular for maximizing the radio signal coupling with another antenna device.

Dependencies are inferred from the claim text.