The Unimast Concept ‐ a Major Departure in Shipboard Radar Antenna Installation Philosophy

Abstract

The best topside location for an antenna is on top of the highest mast on the ship, thus affording all‐around coverage and minimum interference. However, usually only one antenna can occupy that site. Modern naval combatants have numerous antennas, and the necessary compromises in mounting all of them means that even the best site is often electro‐magnetically compromised by adjacent structures and other antennas. A contrary approach is to mount larger antennas lower, and to design the ship to minimize blockage. This is “The UNIMAST Concept,” which argues for a single mast on which are mounted all the ship's major rotating surveillance antennas. The larger antennas rotate around the lower part of the mast, while lighter antennas, e.g., surface search, are sited above. This paper discusses the degradation of sidelobes due to present topside design and numerically relates degradation to Electronic Counter‐Countermeasures (ECCM) performance. Removal of that degradation via the UNIMAST Concept requires that a device known as an Annular Rotary Coupler (ARC) be used. The development of just such a high power, wide‐band ARC on a Navy‐sponsored R&D contract is herein described. Also described is the potential backfitting of the UNIMAST Concept to existing ships; e.g., the DDG‐993. Battle damage vulnerability of the UNIMAST Concept with respect to a conventional two mast design is addressed. It is argued that the UNIMAST Concept affords no degradation in vulnerability due to improved potential for protecting vital antenna parts.