Technical Services Options
Available
Related LBA MW Systems Available
The LBA Technology SAMWAS-350 is a heavy duty, compact, very short aperture medium wave transmitter antenna system. The SAMWAS-350 is designed to fit completely on a site as small as 200 feet (60 meters) in radius. Designed to operate on a single frequency from 275 kHz to 530 kHz, it uses a unique electrically short radiator and peripherals to provide reliable and cost effective omnidirectional coverage for DGPS and radio navigation applications. The SAMWAS-350 replaces all previous conventional-type DGPS and NAVTEX antenna systems.
The SAMWAS-350 is capable of transmitting any two frequencies separated by 15% or more in the 285 – 530 kHz medium wave band, when equipped with an LBA diplexing system.
The SAMWAS NAVTEX antenna radiating structure uses no base insulator and is directly grounded. The grounded tower provides inherent system lightning protection, and permits easy mounting of other antennas for communications, such as for the USCG Rescue 21 program, or for microwave links, without impact on medium wave transmission.
Unsurpassed Range Vs. Height Coverage
Performance
The SAMWAS-350 can provide 300 kHz DGPS correction signals for safety and
warning information to mariners over approximately 87% of the groundwave and
skywave coverage achievable from a full ¼ wave vertical antenna, using a
structure under 40% of that height. Even better coverage performance is
realized on the 490 and 518 kHz NAVTEX GMDSS frequencies.
Advanced Radiator Design
The low-Q design
of the SAMWAS-350 DGPS/NAVTEX antenna system minimizes voltages compared to
high-Q conventional designs. Because of its low-Q trapezoidal feed design,
more transmitter power gets through the antenna radiator, safely, than in
conventional systems. System stability is unmatched by conventional whips and
narrow towers. The low-Q design, coupled with a proprietary top loading and
ground reference system, isolates the antenna system impedance from changing
earth conditions, while providing a low loss ground termination path.
Overall system height is 350 feet (60.6 meters) above ground. The high efficiency system utilizes an insulated vertical radiator antenna tower with proprietary enhanced top loading and a trapezoidal symmetrical unipole Q-reduction system. The radiator is rated for 5000 watts, MSK modulated, continuous duty, which is conservative for reliable service in DGPS and NAVTEX applications. Higher power levels may be accommodated on request.
Medium intensity strobe lights and a toroidal ring air gap transformer typically provide aviation hazard lighting.
Standard subsystem components are to EIA/TIA-222-F. Typical tower structure components are hot-dip galvanized. Safety features include safety climb devices.
The antenna tuning system provides an interface between the DGPS/NAVTEX transmitting Tower Radiator Subsystem and a 50-ohm coaxial transmission line. Selection of ATU is a function of the operating power. The ATU-5 is rated for 5000 watts, MSK or PSK modulated, continuous duty within in the 300 and 500 kHz bands. Antenna tuning systems for higher or lower transmitting power can be provided with similar performance to the ATU-5. The inherent stability of the low-Q antenna makes constant retuning unnecessary. The system is highly reliable, as there are no active components or control circuits in the LBA ATU systems.
Optional ATU-(*)SFA frequency agile tuning unit for 518/490 kHz: The SAMWAS-350 system can be supplied for dual frequency operation using the ATU-(*)SFA. This unit is designed to take two inputs and sequentially switch them in accord with non-conflicting time slots to provide a two frequency NAVTEX broadcast capability.
While a ¼ wave buried copper wire ground plane is recommended, above ground and shorter buried ground system may be accommodated. To enhance stability of the short radiator under varying weather and earth conditions, and to improve displacement current collection at the base of the tower, a proprietary cantilevered six element radial capacitance reference is provided for above ground installation on the Radiator Subsystem base structure.
Minimum Life Cycle Support Costs
The SAMWAS system
components are designed for the high reliability and minimum life cycle support
costs demanded by critical DGPS, NAVTEX and radio navigation missions. Using
standard parts and maximum commonality in subsystems ensures lowest cost life
cycle maintenance.
High Reliability
Reliability is
further enhanced by the use of galvanically compatible structural materials,
computer confirmed mechanical and electrical safety factors, and special
attention to insulator endurance under salt spray and high solar conditions.
The SAMWAS antenna system radiating structure uses high-flashover, corona
protected guy insulators as needed to protect against lightning and
other voltage-induced outages.
Since installation and performance can be influenced by geotechnical siting conditions, coupled RF energy from nearby antennas, and other local effects, an LBA site survey before design completion is recommended.
Technical Services Options Available:
- Turnkey construction and commissioning: Site survey, design, permitting, site preparation, construction, and commissioning services on an E, F & I basis using qualified resources. Includes “as-built” documentation.
- A la Carte engineering services: Qualified personnel can be provided for such services as site qualification, installation commissioning, and performance verification.
- Inspection, rehabilitation and upgrade of existing transmitter systems.
- Emergency and maintenance service: Available on an
off-air response or routine basis for all system components, including
scheduled inspections and periodic performance revalidation.
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Related LBA MW Systems Available:
- SAMWAS-100: Efficient short aperture antenna system based on a 100-foot tower for the DGPS and NAVTEX bands.
- SAMWAS-200: High efficiency short aperture antenna system based on a 199-foot tower for the DGPS and NAVTEX bands.
- TUP-3: Family of truck and trailer (C-130 qualified) transportable systems for 250-2500 kHz tactical applications.
- TGR-50: Low power,
man-carry emergency system for 285 - 5000 kHz tactical applications.
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For a quotation or technical assistance, use the
or contact Jerry Brown via email or call 800-522-4464
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3400 Tupper Drive (27834),
P.O. Box 8026
Greenville, North Carolina 27835
800-522-4464 / 252-757-0279 / Fax 252-752-9155
Email:
Copyright 2003. LBA Group, Inc. All Rights Reserved.