Compact omnidirectional antenna for dipping sonar

An omnidirectional antenna intended to be equipped by a dipping sonar, the antenna comprising multiple elementary transmission rings that are formed around a longitudinal axis of the antenna and multiple hydrophones that are distributed around the longitudinal axis, the antenna being intended to be dipped in water, the hydrophones being separate from the elementary transmission rings, the hydrophones and the elementary transmission rings being fixed to one another in the antenna, wherein the elementary transmission rings and the hydrophones are interlinked along one and the same height measured along the longitudinal axis, wherein the elementary transmission rings and the hydrophones operate at a working frequency of less than 8 kHz, wherein a first minimum cylindrical volume around the longitudinal axis occupied by the elementary transmission rings has a diameter D1, a second minimum cylindrical volume around the longitudinal axis occupied by the hydrophones has a diameter D2 and the difference in absolute value between the two diameters D1 and D2 remains less than 30%, of the smallest of the two diameters D1 and D2, wherein the diameter ratio of the two volumes is constant regardless of whether the antenna is in operation or in a storage position and wherein the projections from the phase centers of the hydrophones in a horizontal plane (P) that is perpendicular to the longitudinal axis, or in a vertical plane (V) containing the longitudinal axis, are spaced apart by a spacing of less than λ/3, λ being the wavelength at the working frequency, the hydrophones being distributed in rings formed around the longitudinal axis in the horizontal plane (P), the spacing (p2), referred to as the horizontal spacing, between two hydrophones is the length of the chord between two neighboring hydrophones over the diameter in question.