Gharib, A; (2015) Modelling and Simulation of the Topside Electromagnetic Environment of a Naval Combatant in Concept Design. Doctoral thesis , UCL (University College London).

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Abstract

The topside of a naval combatant must accommodate a plethora of highly sophisticated and computerised electromagnetic sensors in order for the ship to effectively fight, both to attack and defend. The electromagnetic sensors serve as the eyes and ears of the ship, and without them the ship would be very vulnerable. Since the topside of a naval ship has limited space, antennas must be sited close to each other (co-site). Many of the topside antennas are required to transmit and receive at similar bands of operating frequencies and, at times, they may be required to operate simultaneously. This gives rise to electromagnetic interference (EMI) which causes performance degradation of the equipment, blockage of communication channels, impairment of the on board sensors and even burning out of the inadequately protected equipment. One of the key challenges faced by ship designers at the concept phase of ship design is the need to effectively distribute topside electromagnetic (EM) sensors to avoid EMI. This is difficult to predict especially as in concept design the ship configuration and the EM systems characteristics will change as different arrangements are explored. The likely interference between shipboard antenna systems can be assessed by computational electromagnetic (CEM) tools which model the ship and its topside antenna systems. To tackle this problem, a general purpose and commercially available electromagnetic simulation package, Computer Simulation Technology (CST), has been employed as a rapid and cost effective method for handling the EMI problems in Early Stage Ship Design (ESSD). Using CST, the project initially modelled the recently in service Royal Navy Type 22 Batch II Frigate and its topside sensors. The EM sensor models on the Type 22 Batch II Frigate model were then simulated against each other in order to determine the EMI coupling between them. To benchmark these EMI coupling simulations, validation of a certain number of CST simulations has been carried out using two physical scale models of the Type 22 Batch II Frigate. After obtaining the required confidence in the reliability of the simulation package, a CST based approach for prediction of topside EMI/EMC has been developed. The approach has then been 3 applied on an early design study for a Future Patrol Ship to predict the likely EM interactions between its topside antennas. Finally, in order to assess the likely free space antenna interference, MATLAB based codes have been developed. These will allow quick evaluations of the magnitude of antenna interference in free space. Thus, they would enable the project sponsor to determine antenna interactions between certain shipboard EM sensors without requiring to use a CEM tool.

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