Omnidirectional antenna

Patent metadata

Field	Value
Publication number	US-10789928-B2
Application number	US-201515514373-A
Country	US
Kind code	B2
Filing date	Sep 25, 2015
Priority date	Sep 26, 2014
Publication date	Sep 29, 2020
Grant date	Sep 29, 2020

Abstract

An omnidirectional antenna to equip a sonar, the antenna centered around a longitudinal axis and comprises an assembly of emission rings stacked along the longitudinal axis, each emission ring formed around the longitudinal axis. The emission rings are assembled in groups of ring, the antenna comprises at least two groups of rings and each group of rings comprises at least two rings, the inter-ring spacings between the rings of one and the same group and the inter-group spacings between two successive groups of rings chosen so as to optimize the emission bandwidth and the sound level.

First claim

The invention claimed is:

1. An omnidirectional antenna intended to equip a sonar, the antenna being centered around a longitudinal axis, the antenna comprising:
an assembly of emission rings stacked along said longitudinal axis, said emission rings being directly immersed in a dielectric fluid, each emission ring being formed around said longitudinal axis, wherein each ring constitutes a vibrating ring in said dielectric fluid and comprises an internal cavity including an internal fluid, each ring presenting at least two resonance frequencies acoustically coupled to said fluid, said resonance frequencies comprising a cavity frequency corresponding to a cavity mode and a radial frequency corresponding to a radial mode,
wherein the emission rings are assembled in groups of rings,
the groups of rings comprising at least two groups of rings,
each group of rings, of the groups of rings, comprising at least two rings, and
an inter-ring spacing between the rings of one and the same group of rings are a function of the cavity frequency of the group of rings while an inter-group spacing between two successive groups of rings are a function of a frequency of operational use of the emission rings,
wherein the inter-ring spacing between the rings of one and the same group of rings is furthermore chosen as a function of the radial frequency of the group of rings.

2. The omnidirectional antenna as claimed in claim 1 , wherein the rings are made of piezoelectric material.

3. The omnidirectional antenna as claimed in claim 1 , wherein the sum of the inter-group spacing between two groups of rings p, of the inter-ring spacing d between two of rings and of twice the height of a ring is substantially equal to half the wavelength of the frequency of operational use of the emission rings.

4. The omnidirectional antenna as claimed in claim 1 , wherein the inter-ring spacing between two rings of one and the same group of rings is chosen so as to position the cavity frequency of the group of rings with respect to the radial frequency of the rings of the group of rings.

5. The omnidirectional antenna as claimed in claim 1 , wherein the cavity frequency of each ring is coupled with the radial frequency of said ring.

6. The omnidirectional antenna as claimed in claim 1 , wherein the internal cavity of each emission ring is in contact with said dielectric fluid.

7. The omnidirectional antenna as claimed in claim 1 , wherein the antenna is housed in a leaktight enclosure filled with said dielectric fluid.

8. The omnidirectional antenna as claimed in claim 7 , wherein the enclosure is over-pressurized.

9. The omnidirectional antenna as claimed in claim 7 , wherein the enclosure is placed in hydrostatic equilibrium with the exterior medium.

10. The omnidirectional antenna as claimed in claim 1 , wherein the rings are fed group-wise in parallel.

11. The omnidirectional antenna claimed in claim 1 , wherein a group of rings comprising more than two rings and the inter-ring spacing between two rings of said group varies within the group.

12. The omnidirectional antenna claimed in claim 1 , wherein the inter-group spacing between two groups of rings of the antenna varies for the assembly of groups of rings of the antenna.

13. The omnidirectional antenna as claimed in claim 1 , wherein in the radial mode for a ring is obtained by alternate extension/compression of the material constituting the ring, and the cavity mode for a ring is obtained by causing the internal fluid included in the internal cavity to resonate.

14. The omnidirectional antenna as claimed in claim 13 , wherein the cavity mode depends on the height of the ring.

Assignees

• Thales Sa

Inventors

• Lagier Yves
• LARDAT Raphaël
• Andreis Daniel

Classifications

• G10K11/008 Primary

  Arrays of transducers (seismic streamers, see G01V1/20) · CPC title