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Advanced Enclosed Mast/Sensor (AEM/S)

The US Navy's first-ever advanced hybrid composite structure, known as the Advanced Enclosed Mast/Sensor (AEM/S) System, was installed aboard the Spruance Class multimission destroyer USS ARTHUR W. RADFORD (DD 968), at Norfolk Naval Shipyard, Portsmouth, Virginia. The ship was the platform for extensive testing of the new mast by the Navy. The new, advanced composite mast, which the Navy described as "revolutionary and spectacular," was built and designed by an Integrated Product Team (IPT) -- known as "The AE MIS System Masters" -- made up of technical experts drawn from diverse Navy and industry activities nationwide. The AEM/S System is a 93' high, hexagonal structure, 35' in diameter, enclosing existing radars and providing important signature and other operational benefits. By enclosing major antennas and other sensitive equipment, the AEM/S System protects them from the weather. This reduces maintenance, as well as providing significantly reduced radar signature.

Ingalls Shipbuilding division of Litton Industries, the ATD's prime industrial support activity, was responsible for fabrication of the AEM/S System Mast and a myriad of associated test articles. To support this effort, Ingalls established a composites complex and developed a temporary, liftable building in which to fabricate the mast and the test articles. In addition to fabrication, Ingalls developed detailed plans for installation aboard the RADFORD.

The AEM/S System is a high-risk, high-payoff Advanced Technology Demonstration. Benefits and payoffs include:

Enhanced Performance: The AEM/S System is fabricated with an advanced composite hybrid frequency selective surface (FSS), designed to allow passage of own-ship sensor frequencies while reflecting other frequencies. Improved sensor performance results from reduction of blockage, false targets and sensor downtime, thereby dramatically enhancing the ship's war-fighting capability.

Affordable Low-Cost Manufacturing: The AEM/S System utilizes unique materials, creative structures and innovative manufacturing techniques, yet the mast can be produced in a shipyard environment.

Affordable Reduced Life-Cycle Costs: The AEM/S System's enclosed structure protects RADARs and communication antennas from weather exposure and provides all-weather access for repair, thus greatly reducing the need for repair, maintenance costs, replacement costs and risk of failure.

Enhanced sustainability: The AEM/S System concept will enable rapid and seamless transition to the next generation of technology. Features such as embedded sensors, planar arrays, integrated antennas, low observable signatures, reduced topside weight -- all contribute to the Navy's objectives for future warships. Accelerated transition of AEM/S System technology to the LPD 17 is already underway, along with evaluation of its applicability to the SC 21 and CV(X).

The upper half of the AEM/S System is designed to allow passage of own-ship sensor frequencies with very low loss while reflecting other frequencies. It is divided into two radome-like compartments; the upper compartment houses the MK 23 TAS antenna, and the lower encloses the SPS-40 air search radar antenna.

The whole system is a free-standing, fully integrated composite structure. Structural design requirements for strength and stiffness meet Fleet requirements for vibration, shock and fatigue. Signature and electromagnetic design requirements are based on criteria associated with sensor and antenna performance, electromagnetic interference, lighting protection electromagnetic shielding, electrical bonding and grounding. The objective of this team effort was to develop an affordable mast by fully integrating sensor technology, electromagnetics, signature reduction, advanced materials structures and manufacturing technologies. The AEM/S System will result in significant new design options for both future surface ships and major upgrades. This program is a necessary step in the development and deployment of next generation radar and communication systems.

References

• Navy's AEM/S System Mast Leads the Fleet Into the 21st Century Thursday, July 17, 1997
• Advanced Enclosed Mast/Sensor and Visual Display Workshop Final Report 10 December 1997