Buoyant Wire Antenna (BWA) System

U.S. Navy Photo
Bouyant Wire Antenna System
Submarine Communications

Buoyant Wire Antenna System
Submarine Communications
HF
HF
VLF/LF
MF/HF
In today’s environment of combined operations
and Network Centric Warfare (NCW) concepts, the ability
of submarines to communicate over a wide range of operating
postures has become increasingly important. Modern submarines
are required to receive messages from their home base, and on
occasion, are required to communicate with surface ships and
aircraft. This must be accomplished while the submarine remains
undetected with minimal negative impact on mission priorities
and effectiveness. In addition, the introduction of Air
Independent Propulsion (AIP) into submarines and the
embracement of Network Centric Warfare by most navies
has elevated the requirement that today’s submarines have
the ability to communicate from below periscope depth. These
tactical concerns present a difficult challenge to a submarine
commander given that presently most conventional submarines
throughout the world’s navies must come to periscope depth
and raise a mast or whip antenna to receive or transmit
messages. Periscope depth operations are generally more
perilous, crew stressing and difficult than operations at depth
due to increased risk of detection, surface traffic, depth keeping
requirements, and sea state effects. Also, since a line source
presents the optimum geometry for return signals to surfacesearch
or fire-control radars, employment of the vertical mast
or whip antenna puts the submarine in a condition of significant
vulnerability.
Lockheed Martin has developed a complete line
of Buoyant Wire Antenna Systems designed to meet this
challenge. Buoyant Wire Antenna (BWA) Systems provide
the submarine the capability of receiving in the VLF/LF/MF/
HF (10 kHz - 35 MHz) communication band while remaining
fully submerged. In addition, it is also possible to configure a
BWA system for reception at VHF and the lower UHF bands
and transmission in the 2 - 10 MHz band.
In-Line Amplifier —
Actual Size
Buoyant Wire Antenna Systems
provide the submarine the capability
to communicate from below periscope
depth.
Buoyant
Wire Antenna
Buoyant Wire Antenna Systems are comprised of three
major components: the Buoyant Wire Antenna, a Deployment
System and an Antenna Coupler.
The standard Buoyant Wire Antenna is either 610 m
or 730 m in length, depending on the variant of Deployment
System in use, with a diameter of 16.5 mm. Shorter and longer
antenna lengths are also available. The standard antenna incorporates
an in-line amplifier which operates in the frequency range
of 2 MHz to 35 MHz; other versions provide operation below
and beyond the 2 MHz - 35 MHz range.
The Deployment System consists of an antenna winch
and associated winch control apparatus. Using the winch control
equipment, a single operator can command the winch to pay out
the antenna, hold the antenna while it is being towed and retrieve
the antenna. Deployment, tow and retrieval of the buoyant wire
antenna can be conducted at a wide range of submarine speeds
and at depths in excess of 400 m. With the complete scope
of the standard antenna deployed, a submarine is capable of
carrying out communication at depths in excess of 125 m.
Upon completion of communications, the antenna may be
completely recovered or remain deployed without adverse
impact to submarine operations.
Two types of Deployment Systems can be provided:
an electrically driven winch located outboard of the pressure
hull and controlled by inboard electronic units or a hydraulically
driven winch located inboard of the pressure hull and controlled
by manually operated hydraulic valves.
A special Antenna Coupler is required with Buoyant
Wire Antennas. This coupler contains unique antenna impedance
matching circuits, low noise amplifiers for improved system
sensitivity, power supplies to power the in-line antenna amplifier
and 50 ohm output drivers. The Antenna Coupler allows
standard, VLF-HF communication receivers to operate with the
Buoyant Wire Antenna.

Lockheed Martin has developed a
complete line of Buoyant Wire Antenna
Systems, for both modern diesel electric
and nuclear powered submarines.
Inboard Deployment System
For larger new construction submarines or where space is
Inboard
available on existing submarines, Lockheed Martin offers an
Deployment
inboard deployment system for buoyant wire antennas. This system is
System
backed by more than 30 years of successful operation beneath the oceans
of the world. Hydraulically operated, the inboard deployment system operates
over a wide range of deployment/retrieval speeds and can be tailored to match the
capacity of the available ship hydraulic system. The inboard deployment system
offers an advantage over the outboard system, in that the equipment is accessible
by the crew while the submarine is submerged, thus allowing different antenna
types to be streamed from the submarine without having to surface.
Outboard
Deployment
System
Winch
Drive Unit
Winch
Control Unit
Outboard Deployment System
For retrofit on existing submarines, or for new designs with limited interior space,
Lockheed Martin offers a unique and highly compact outboard deployment system for
buoyant wire antennas. The deployment system can be customized to fit in the forward
or aft end of the fin or located beneath the submarine superstructure. Inaccessible while
submerged, the outboard deployment system is designed to ensure high reliability,
high survivability, low-noise operation and to withstand the harsh ocean environment.
This is accomplished through the use of direct drive, ultra quiet brushless DC motors,
corrosion resistant materials, and complex shock mounting systems. The outboard
system is remotely operated from within the submarine, powered from a DC and/or
AC power bus and operates over a wide range of deployment/retrieval speeds.
An integral and essential part
to any buoyant wire antenna system is
the antenna coupler. Modern, state-of-theart
buoyant wire antenna couplers utilize
sophisticated electronic circuitry designed
specifically to allow proper interface
between the outboard antenna assemblies
and inboard communication receivers
The uncompensated amplitude
and phase response of a buoyant wire are
a complex function of frequency. Further,
the lower level signals captured by the
antenna are attenuated by the outboard
transmission line which routes the
antenna signals inboard. It is therefore
necessary that appropriate amplitude and
phase compensation circuits be employed
and that the front end utilize extremely
low noise preamplifiers. In addition it
is necessary for the coupler to employ
highly specialized, very low noise power
supply circuits which multiplex DC
Buoyant Wire Antenna Coupler
power onto the same transmission line
to operate the outboard in-line amplifiers
of the buoyant wire antenna assembly.
Lockheed Martin has done
extensive research leading to the
development of a range of Buoyant
Wire Antenna Couplers. These multiband/multimode
couplers allow for the
use of certain buoyant wire antennas
for reception of signals from 10 kHz
to 35 MHz, and with other antennas,
for reception at higher frequencies and
transmission in the HF band.
This equipment has been carefully
designed to operate compatibly in
the submarine radio room environment.
They meet the EMI/EMC requirements
of MIL-STD-461 and the environmental
requirements generally imposed for
submarine equipments.

©2006
Lockheed Martin Corporation
All Rights Reserved
Lockheed Martin MS2
Seven Barnabas Road
Marion, MA 02738
An ISO9001:2000 Company
Sea-Air Systems
508.748.1160 (x138)
e-mail: douglas.Q.williams@lmco.com
OCT2006/NDCR/20060008/Covers:2006