EP2050161A1

EP2050161A1 - Submarine wire antenna

Info

Publication number: EP2050161A1
Application number: EP07823381A
Authority: EP
Inventors: Eric Pierron
Original assignee: Bilbo Marine Technique Industrie
Current assignee: Bilbo Marine Technique Industrie
Priority date: 2006-08-11
Filing date: 2007-07-31
Publication date: 2009-04-22
Anticipated expiration: 2027-07-31
Also published as: ATE506714T1; EP2050161B1; FR2904892B1; WO2008020121A1; FR2904892A1; DE602007014057D1

Abstract

Submarine RF communication device (1) comprising a coaxial cable (11), an electrically conducting antenna element (12) and an amplifier (13) linked to the said antenna element (12) and to a first electrical conductor (111) of the coaxial cable (11), the amplifier (13) being suitable for amplifying a signal received (S2) by the said antenna element (12) and for transmitting an amplified signal (S2) via the said first electrical conductor (111) of the coaxial cable (11). The amplifier (13) is disposed at an end (112) of the said coaxial cable (11) and at least one portion of the antenna element (12) extends along at least one portion of length of the said coaxial cable (11).

Description

WIRED ANTENNA FOR SUBMARINES

The present invention relates generally to the field of wireless communication using a radio antenna adapted to be connected to a submarine.

More particularly, the invention relates to a submarine radio communication device comprising a coaxial cable, an electrically conductive antenna ^" element ^" and an amplifier connected to said antenna element and a first electrical conductor of the coaxial cable. amplifier being adapted to amplify a signal received by said antenna element and to transmit an amplified signal via said first electrical conductor of the coaxial cable.

In order to pick up or transmit radio signals from a submarine it is known to use devices with floating antennas, these antennas extending from the submarine to reach the surface of the water body. under which plunges the submarine.

FIG. 1A represents one of the first types of submarine known communication device. The antenna of Figure IA is formed of an electrically conductive wire and surrounded by an electrical insulation sheath of positive buoyancy material. The antenna 12 of FIG. 1A is towed by a submarine 17 and the end of the conducting wire which is distant from the submarine is connected to the ground (the term "mass" describes any conductive element having the electrical potential of the environment in which the device of the invention plunges). Such an antenna is particularly useful for capturing signals at very low frequencies (frequency band known as VLF) and / or low frequencies (frequency band known as LF), but is poorly suited for capturing signals. high frequency signals (frequency band known as HF).

A submarine radio communication device improving the previously defined type is for example described in US Pat. No. 4,774,519. This device of the prior art shown in FIG. 1B in the general form of a divided flexible cable 11 in two disjointed parts of cable connected together by an amplifier 13.

The antenna element 12 is located at a distance from the cable portion connecting the sub-amplifier to the amplifier 13 and away from the amplifier which serves as relay.

The antenna element is disposed at the end of the cable which has a length exceeding 300 meters. Amplifier 13 is integrated on the cable to relay and amplify the signal from the antenna element.

The force required to pull the antenna element passes entirely through a resistive housing containing the amplifier 13. The cable connecting the submarine 17 to the amplifier

13 is a coaxial cable which comprises a conductor 111 serving as a coaxial cable core and a peripheral conductor 113 of the coaxial cable, these two conductors are electrically insulated from each other by an insulating sheath. The antenna element 12 which is connected to the amplifier pulled by the coaxial cable consists of a wire placed in an insulating sheath, this wire being connected to ground at its end which is remote from the amplifier 13. This type of device

^• --'- goose communication IB figured allows ^"" dice to capture and transmit underwater frequency signals

VLF, LF and HF (see definitions above).

In this context, the present invention aims to provide a robust radio communication device and allowing a submarine to receive radio signals.

To this end, the device of the invention, moreover in accordance with the generic definition given in the preamblev defined above, is essentially characterized in that: the amplifier is disposed at one end of said coaxial cable and; in that at least a portion of the antenna element extends along at least a portion of length of said coaxial cable.

Having an amplifier disposed at the end of the coaxial cable rather than the length of the cable, between two coaxial cable portions, is advantageous from the standpoint of ruggedness. device since few traction forces pass through the area of the device containing the amplifier.

Indeed, when towing the device by a submarine, the mechanical forces exerted on the area of the device containing the amplifier are reduced compared to what they would be if the amplifier was placed between two disjoint parts cable. The tensile forces are distributed over the entire length of the coaxial cable, and the minimum tensile stress is located at the end of the device which is opposite ^"to ^point""'d ^1' cable tie. The ^constraint" minimum tensile is therefore at the end of the coaxial cable carrying the amplifier, this end being opposed to the submarine with respect to the coaxial cable.

In addition, the device of the invention has substantially constant bending characteristics over its entire length and this up to the end of the coaxial cable, which reduces the risk of having areas of potential rupture of the device between the flexible cable and the amplifier - .q.uά. is generally arranged in a protective case for example flexible or rigid.

By arranging the amplifier at the end of the coaxial cable, the risk is reduced that the amplifier is damaged during the winding of the device on a winch drum, since the amplifier is then always placed outside the drum in a zone. not crushed by the coaxial cable. The fact that at least a portion of the antenna element extends along at least a portion of length of said coaxial cable also promotes the mechanical strength of the communication device because the antenna element is partly carried by the coaxial cable and is not necessarily carried by the housing containing the amplifier. In addition, the core of the coaxial cable is designed to be resistant to the mechanical stresses of underwater traction.

It is for example to ensure that said portion of antenna element is spirally wound along ^'de-riadite length portion of said coaxial cable ^-.->' ---- • '- ^•' This feature of This winding enables the mechanical strength of the device to be increased while improving the reception characteristics of the antenna element.

For example, it may be ensured that said antenna element is formed of an antenna conductor wire having a diameter of less than 2 millimeters and preferably less than 1.5 millimeters. The fact that the antenna element is formed of a low-diameter wire makes it possible to avoid a risk of capacitive coupling between the antenna element and at least one of the conductors. coaxial cable. In fact the antenna element is chosen so that the surface of this element which is opposite the conductors of the coaxial cable is small in relation to the surface of the conductors of the coaxial cable.

For example, it is possible to ensure that said coaxial cable which comprises said first conductor The electrical circuit further comprises a second electrical conductor, the first and second electrical conductors being concentric and insulated from one another by an electrical insulation sheath.

The device of the invention is adapted to have a positive buoyancy in seawater in this case the insulation sheath is here preferably chosen to promote this positive buoyancy and is therefore in material of density less than 1 as the polyéthyrêne. ^""""^{''":" • '•} - ~ ^ ---

For example, it is possible for the device of the invention to comprise an electrically insulating outer sheath extending along said coaxial cable.

Such a sheath on the one hand protects the device and on the other hand makes it possible to define an outer profile of the relatively constant device over the entire length of the device. This constant profile of the sheath allows to cQiïl ^{'dissertation-≈Je} device in a hull structure passes the submarine having a seal rubbing along the outer sheath. The regularity of the profile of the outer sheath reduces the risk of water passing between the outer sheath and the seal of the sheath.

This outer sheath is preferably made of a material having a positive buoyancy in the water in order to promote the surface rise of the antenna element. For example, it is possible for said antenna element to have a first end connected to said amplifier and another end connected to a grounding electrode of the antenna element, this electrode being oriented towards the outside of the antenna element. device.

This embodiment makes it possible to improve the reception characteristics of the antenna for certain radio signal frequency bands. For example, it is possible to make said electrode

^{~ '';} ^'Mi-S-E' to the mass of the antenna element comprises nή &'ring of electrically conductive material, this ring being arranged to electrically connect the antenna element to a surrounding material the device such as seawater.

The fact of using a ring for the grounding makes it possible to promote electrical contact with the water surrounding the antenna element and this even if the antenna element is pivoted along a longitudinal axis of the coaxial cable. .

For example, it is possible for the antenna element to be embedded in an electrical insulator adapted to electrically isolate this antenna element from a material surrounding the device such as seawater.

This embodiment makes it possible to protect the antenna element against electrical disturbances originating from the environment of the device. The antenna element can be: - be completely isolated throughout its length and be connected at one end to the amplifier;

- is insulated along its entire length and connected at one end to a grounding electrode and at the other end to the amplifier.

The choice between these embodiments is performed depending on the reception characteristics that are desired and particularly in frequency bands functions ^"of signal- 'frert- ^ hile it is desired to capture.

For example, it is possible for the second electrical conductor of the coaxial cable to be connected to an electrode for grounding the coaxial cable. This embodiment may be useful to reduce the risk of capacitive coupling between the antenna element and the second conductor of the coaxial cable.

For example, the device of the invention may comprise an electronic measurement assembly of at least one physical quantity located at the end of said coaxial cable and in the vicinity of said amplifier.

Thanks to this embodiment, the device of the invention can advantageously be used to receive a radio signal via the antenna element and to measure a physical quantity in the immediate environment of the end of the coaxial cable where is disposed the amplifier. Such a physical quantity can be pressure by a pressure sensor, which allows the submariner to detect when the antenna element has reached the surface of the water body or possibly the depth of the element. antenna under this body of water. The sensor used may for example be a temperature and / or salinity sensor thus making it possible to determine salinity or temperature profiles without having to deploy for it a specific device such as a bathythermic probe.

For example, it may be ensured that said electronic unit for measuring physical quantity is electrically connected to said first cable conductor

Coaxial so as to transmit a signal representative of said at least one physical quantity measured via said first conductor of the coaxial cable. This embodiment is advantageous because it makes it possible to use the conductor (s) of the coaxial cable for

20 transmit to the submarine both signals

CΞ. --- i. representative of the radio signal picked up by the antenna element and signals representative of the measured physical quantity. This embodiment makes it possible to avoid adding a specific cable to the

Communication of signals representative of the physical quantity.

For example, it may be ensured that said electronic measurement assembly comprises at least one sensor for

Physical magnitude electrically connected to a bandpass filter and a modulator for generating said signal representative of said at least one physical quantity.

This embodiment makes it possible to modulate the signal representative of the physical quantity in a range of frequency or amplitude remote from the frequency band used by the amplifier to transmit the signals representative of the radio signal picked up.

In this embodiment, the signal representative of the physical quantity does not disturb the transmission of the signal representative of the wireless signal.

For example, it is possible for the device to comprise a DC generator having at least one power supply terminal connected to said first conductor of the coaxial cable and for the amplifier to be electrically powered by said DC generator via said coaxial cable.

This embodiment makes it possible to deport the power supply of the amplifier and possibly that of the electronic measurement unit (if the electronic assembly - • of winding is - adapted to be powered via the first conductor of the cable. coaxial) to the submarine.

Other features and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limiting, with reference to the appended drawings, in which: FIG. 1A represents a device of the prior art whose antenna element is in the form of a wire electrically insulated and extending from the back of a submerged submarine to the surface of the body of water; Fig. 1B shows a prior art device according to US Pat. No. 4,774,519; FIG. 2 represents the device according to the invention when it is used by a diving submarine for receiving radio signals; 3 shows in section a 10 Communication according to the invention with a grounding device ^'of the second electrical conductor ^"of the coaxial cable and with a generator powering the amplifier via the first conductive member of the coaxial cable ;

FIG. 4 shows the device of the invention according to FIG. 3 but having in addition a grounding of one end of the antenna element which is distant from the amplifier and close to the submarine; FIG. 5 represents a device according to

The invention according to Figure 3 but having in addition receiving device of a signal --is.eαόmfedr-re via the second electrical conductor, this secondary signal being located in a frequency band different from that to which the signal amplified by

The amplifier which passes through the first electrical conductor; FIG. 6 represents a device according to the device of FIG. 6 and furthermore having an electronic measuring assembly of at least one size

30 which generates a signal modulated in frequency or amplitude depending on the measured physical quantity and an electronic signal collection assembly thus modulated by the electronic measuring assembly.

As previously announced, the invention relates to a submarine communication device.

FIG. 1B shows a device of the prior art equipped with an amplifier 13 interconnecting an end 112 of the coaxial cable 11 and an end of the antenna element 12 formed by an electrically insulated wire. This amplifier 13 is located at a distance of 300 ^"" m or more ^de-: the end of the coaxial cable 11 which is connected to the submarine 17 towing the device 1. This amplifier 13 is also located more than 30 meters from the free end of the antenna element 12. This antenna element 12 which has a length of more than 30 meters is used to pick up a wireless signal which is amplified by the amplifier 13 before being retransmitted to the submarine 17 via the coaxial cable 11.

In contrast to the prior art shown in FIG. 1B, where the amplifier 13 is arranged between the coaxial cable 11 and the free wire serving as antenna element 12, the device of the invention as shown in FIG. 2, 3, 4, 5 and 6 comprises an amplifier 13 placed at the end of the coaxial cable 11 which also constitutes an end of the device 1 of the invention. In these same figures 2, 3, 4, 5, 6 the amplifier 13 is connected to one end of the antenna element and this Antenna element 12 extends along the coaxial cable at its periphery.

According to the invention, the antenna element shown in FIGS. 2, 3, 4, 5 and 6 has a length of between 5 and 40 meters and preferably between 5 and

10 meters whereas in the prior art shown in Figure 1, the antenna element to a length greater than 30 m. The total length of the coaxial cable of the device of the invention is intended to be between 300 and 800 meters. In the example of the figures

^" 2,3,4,5,6, ^" the antenna element extends along its entire length along the coaxial cable 11.

As shown in FIGS. 3 to 6, the submarine wireless communication device 1 of the invention comprises:

a coaxial cable 11; an electrically conductive antenna element 12 and; an amplifier 13 connected to said antenna element 12 and to an electrical conductor 111 of the antenna. _^ r-

The coaxial cable 11 is flexible and of cylindrical section and comprises a first electrical conductor 111 placed at its center.

The coaxial cable 11 further comprises a second concentric electrical conductor 113 of the first conductor 111. This second conductor 113 is formed by a braid surrounding the first wire-shaped cable 111. The first and second conductors 111, 113 are disjointed one. on the other and isolated from each other by electrical insulation sheath 114 of flexible plastic preferably having a positive buoyancy.

The coaxial cable 11 has an end 116 intended to be attached to a submarine structure such as a winch drum and a second end 112 intended to be placed at a distance from the submarine, at the surface of the water body below which plunges the submarine.

The amplifier 13 is connected to the end -112 of the coaxial cable and more precisely to the first electrical conductor 111 of the coaxial cable 11 so that the amplifier 13 amplifies a signal Sl received by said antenna element 12 and transmits an amplified signal S2 via said first electrical conductor 111 of the coaxial cable 11. The amplifier 13 must have sufficient power to transmit the signal S2 over the entire length of the coaxial cable 11 to a first onboard electronic assembly 19 of the submarine 17 able to receive and interpret S2.

The antenna element 12 may have a coaxial braid shape. However, as shown in all of FIGS. 2 to 7, the antenna element 12 preferably has the shape of a wire of small diameter in relation to the diameter of the second electrical conductor 113 of the coaxial cable 11 so as to avoid coupling. capacitive between the antenna element 12 and the coaxial cable 11. For this the antenna element has a diameter less than 2 millimeters and preferably less than 1, 5 millimeter whereas the diameter of the second braided conductor 113 is preferably greater than 6 millimeters and preferably less than 14 millimeters. The antenna element 12 is fixed at the periphery of the coaxial cable 11 so as to form a spiral and extend along a length portion of this coaxial cable 11. The length D on which extends the antenna element 12 is preferably greater than 5 meters, preferably less than 40 ^' meters and preferentially less than 10 meters. The coaxial cable 11 has an electrically insulating outer sheath 14 extending along said coaxial cable 11 and the antenna element 12 is preferably inserted in this outer sheath 14 without ever being in contact with the second conductor 113.

In order to facilitate the manufacture of the device according to the invention, the insulating outer sheath 14 is composed of a first insulating part 14a (part inte-rne of the sheath 14) and • d-.un.e -. • ^• It is based isolating 14b (external part of the sheath 14). The first insulating portion 14a is in contact and surrounds the second conductor 113 to electrically isolate it over at least part of its length. The antenna element is spirally disposed around the first insulating portion 14a. Thus this first part 14a forms an electrically insulating sheath arranged at least between the antenna element 12 and the second conductor 113. The second part 14b which also has a sheath shape surrounds the first part 14a and the antenna element 12 and thus defines the outer portion of the outer sheath 14.

The outer sheath 14 has a relatively constant diameter over its entire length, this diameter being greater than or equal to the diameter of the housing in which is placed the amplifier 13 and possibly to the diameter of the housing in which is placed the electronic measuring assembly so the device is easily swallowed in its entirety inside the submarine 17 to be handled. This diameter of the protective sheath 1-4 is preferably chosen to adapt to submarine shells passage systems currently used. For this, this diameter is generally less than 20 mm and is preferably equal to 16 millimeters to plus or minus 5 millimeters.

Preferably, the insulation sheath 114 placed between the first and second conductors and the outer sheath 14 are in electrically insulating materials ^; and of density less than 1 so that the device of the invention has a positive buoyancy. The second electrical conductor 113 is preferably connected to ground by an earthing electrode 115 preferably formed by a peripheral metal ring of the coaxial cable 11 and disposed at the end of the cable 112. In the embodiment of the figures 4, 5 and 6, the end 122 of the antenna element 12 is grounded by a grounding electrode 123 formed by a peripheral metal ring of the coaxial cable 11.

This grounding ring of the antenna element 12 is partially embedded in the outer sheath 14 of the device and more particularly in the second portion 14b of this outer sheath 14. This ring is provided to have a substantially equal outside diameter. and aligned with the outer diameter of the outer sheath 14.

In Te mode ^"embodiment of Figure 6, ^the" device 1 comprises, in addition to its amplifier 13, 15 an electronic measurement set of at least one physical quantity on the end of said coaxial cable 112 and proximate said amplifier 13.

This electronic set of physical magnitude measurement 15 is composed of one (or more) sensor (s) of physical size (s) 151 electrically connected to one (or more) filter (s) pass band 152 and one (or more) modulator (s) 153. The modulator 153

^ -allows to transform the signal. : disturbed and transmitted by the physical size sensor 151 into a modulated signal

Smod in frequency or amplitude.

The filter 152 makes it possible to ensure that this modulated signal Smod in frequency or in amplitude 'is included in frequency or amplitude ranges that do not interfere with the signal S2 transmitted by the amplifier 13 on the first conductor 111 of the cable The modulated signal Smod is thus sent as a modulated carrier in a band not used by the other functions of the device. Thus the signal S2 located in frequency bands of 10 to 120 KHz or 1.5 to 20 MHz or 1.5 to 30 MHz. As a function of the frequency band of the signal S2, the frequency of the modulated carrier Smod is selected by the measurement unit 15 to be:

- in a frequency band below 10KHz;

- in a frequency band above 120 kHz and below 1.5 MHz; or above the highest unused frequency, that is to say above 30 MHz.

An electronic reception unit 24 of the signal modulated in frequency or in amplitude by the modulator 153 is on board the submarine 17. This assembly 24 comprises a band pass filter 24a and a modulated signal receiver 24b by the modulator 153. The filter bandpass 24a has its input connected to the first electrical conductor 111 of the coaxial cable 11 and its output connected to the modulated signal receiver 24b so as to let transit to this 24b receiver as if-nals produced by _^ ï 'measuring assembly 15 For-βela the bandpass filter 24a is substantially identical to the bandpass filter 152 of the measurement assembly 15. The receiver 24b receives and demodulates signals representative of the physical quantity measured by the sensor 151, which allows the submariner to perform remote measurements of the submarine.

It should be noted that the measuring assembly 15 and the amplifier 13 are preferably implanted in the same rigid sealed housing. Figures 3, 4, 5 and 6 show a DC generator 16 provided to be implanted aboard the submarine. This generator 16 has a power supply terminal electrically connected to said first conductor 111 via an onboard power supply circuit 18 on the submarine which comprises a coil and first and second capacitors 18b, 18c. The coil 18a of the on-board power supply circuit 18 has a first terminal connected directly to the first electrical conductor 111 and a second terminal connected to a first terminal of the first capacitor 18b, the second terminal of this first capacitor 18b being connected to ground. The second capacitor 18c of the onboard supply circuit 18 is arranged in series with the first electrical conductor 111, between the terminal of the coil 18a and a terminal of the first onboard electronic assembly 19 of the submarine able to receive and interpret the signal S2. This second capacitor 18c serves as a filtering capacitor. In addition to the on-board power supply circuit 18 aboard the

_* - * ^ dispositif- the underwater ude- the invention comprises a remote power supply circuit 20 for receiving the supply current generated by the onboard power supply circuit 18 and transmitted via the first electrical conductor 111. This circuit remote power supply 20 is disposed in the immediate vicinity of the amplifier 13 and is for example arranged in the same housing as the amplifier 13. The remote supply circuit 20 comprises a coil 20a, and first and second capacitors 20b and 20c. The coil 20a has a first terminal connected directly to the first conductor 111 and a second terminal connected to a supply terminal belonging to the amplifier 13. The first capacitor 20b of the remote supply circuit 20 has a first terminal connected to ground and a second terminal connected to the first terminal of the coil 20a. The second capacitor 20c of the remote supply circuit 20 is connected in series between the output of the amplifier 13 through which the amplified signal S2 and the first conductor 111 of the coaxial cable 11 pass.

As shown in the particular embodiments of FIGS. 5 and 6, a bandpass filter 21 may be positioned in series between the second capacitor 20c of the remote supply circuit 20 and the output of the amplifier 13 through which the amplified signal S2 passes. . This bandpass filter 21 is preferably adapted to pass only high frequency amplified signals. In this case, the amplified signal S2 which is received by the first

On-board electronic assembly 19 is a high-frequency signal and a second electronic assembly 22 on board the submarine is used which is distinct from the first on-board electronic assembly 19 to receive signals whose frequency bands are different from the band. frequency of the signal S2. In this case the second onboard electronic assembly 22 is adapted to receive very low frequency signals known by the acronym VLF and low frequency signals known by the acronym LF. For this, as shown in Figures 5 and 6, the second on-board electronic assembly 22 is connected to the second electrical conductor 113 of the coaxial cable 11 in order to receive signals S3 picked up by this second electrical conductor 113. Thanks to this embodiment, the device of the invention makes it possible to receive high frequency signals ( which are in this embodiment the amplified signals S2) passing through the first electrical conductor 111 and low-frequency and very low-frequency signals S3 passing through the second electrical conductor 113 of the coaxial cable 11. In this embodiment the device is particularly versatile since it can pick up radio signals belonging to a very broad frequency band by separating the signals as a function of frequencies and treating these separate signals in channels dedicated specifically to each type of signal. The second on-board electronic assembly 22 comprises first and second bandpass filters 22a and 22b, a coil 22c and signal-aux 22d adapted to analyze signals passing through the second electrical conductor 113 of the coaxial cable 11. The first bandpass filter 22a connects the second electrical conductor 113 to the ground and makes it possible to put the electrical conductor 113 to ground only to unfiltered frequency bands, that is for high frequencies. This first band pass filter therefore preferably has filtration characteristics similar to those of the high frequency filter 21 disposed at the output of the amplifier. With this arrangement, the high frequency amplified signals S2 pass through first electrical conductor 111. The second electrical conductor 113 is dedicated to the transmission of low and very low frequency signals S3.

The second band pass filter 22b has a first terminal connected to the second electrical conductor 113 and a second terminal connected to the signal receiver 22d. This second band pass filter 22b is in this case

10 adapted to pass only signals in ^S3. "Strips of low and very low frequency The coil-22c has a first terminal connected to the second electrical conductor 113 and a second terminal connected to ground 22c This coil has. for function to put the

Second electrical conductor 113 to the ground with respect to the direct current flowing through the second conductor, while not permitting grounding for certain high frequency currents passing through the second conductor 113.

20 ι - i ⁱ s- _™ -Dan the embodiment of the invention -près-enté-- to Figure 6, the device comprises a measuring electronic unit 15 which is supplied electrically by a current flowing through the first

25 and the coil 20a of the remote supply circuit 20.

Claims

1) Submarine wireless communication device (1) comprising a coaxial cable (11), an electrically conductive antenna element (12) and an amplifier (13) connected to said antenna element (12) and a first conductor electrical connector (111) of the coaxial cable (11), the amplifier (13) being adapted to amplify a received signal (S2) by said antenna element (12) and ^'for transmitting an amplified -signal (S2) via said first electrical conductor (111) of the coaxial cable (11), characterized in that:

the amplifier (13) is disposed at one end (112) of said coaxial cable (11) and;

- At least a portion of the antenna element (12) extends along at least a length portion of said coaxial cable (11).

2) A communication device according to claim 1, characterized in that said portion of the antenna element (12) is spirally wound along said length portion of said coaxial cable (11).

3) Communication device according to any one of claims 1 or 2, characterized in that said antenna element (12) is formed of an antenna conductor wire of diameter less than 2 millimeters and preferably less than 1, 5 millimeters. 4) Communication device according to any one of the preceding claims, characterized in that said coaxial cable (11) which comprises said first electrical conductor (111) further comprises a second electrical conductor (113), the first and second electrical conductors (111, 113) being concentric and isolated from each other by an electrical insulation sheath (114).

5) Device according to any one of claims -1 to 4, characterized in that it comprises ^an electrically insulating outer sheath (14) and extending along said coaxial cable (11).

6) Device according to any one of the claims

1 to 5, characterized in that said antenna element

(12) has a first end connected to said amplifier (13) and another end (122) connected to an electrode (123) for grounding the antenna element, said electrode (123) being oriented towards-i external device (1). - • - ^• ^• --'- -

7) Device according to claim 6, characterized in that said grounding electrode (123) of the antenna element (122) comprises a ring of electrically conductive material, said ring being arranged to electrically connect the antenna element (122) to a material surrounding the device such as seawater. 8) Device according to any one of claims 1 to 1 _r characterized in that the antenna element (12) is embedded in an electrical insulator adapted to electrically isolate said antenna element vis-à-vis a material surrounding the device such as seawater.

9) Device according to any one of the preceding claims combined with claim 4, characterized in that the second electrical conductor (113) of the coaxial cable (11) is connected to an electrode (115) for grounding the coaxial cable (11).

10) Device according to any one of the preceding claims, characterized in that it comprises an electronic assembly (15) for measuring at least one physical quantity located at the end of said coaxial cable (112) and close to said amplifier ( 13).

11) Device - according to claim 10, characterized in that said electronic physical magnitude measuring assembly (15) is electrically connected to said first conductor (111) of the coaxial cable (11) so as to transmit a representative signal at least one physical quantity measured via said first conductor (111) of the coaxial cable (11).

12) Device according to any one of claims 10 or 11, characterized in that said electronic measuring assembly (15) comprises at least a physical magnitude sensor (151) electrically connected to a bandpass filter (152) and a modulator (153) for generating said signal representative of said at least one physical quantity.

13) Device according to any one of the preceding claims, characterized in that it comprises a DC generator (16) having at least one power supply terminal connected to said first conductors (113) of the coaxial cable (11) and in ^• that this' l ^r amplifier (13) is ^{"electrically} fed by said direct current generator (16) via said coaxial cable (11).