Design of survivable shipboard HF mast antenna models using the numerical electromagnetics code
Choi, Il Yong
Adler, Richard W.
Lee, Hung Mou
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Modern combat ships are crucially dependent on electromagnetic systems including numerous and varied types of antennas. There are many shipboard communication antenna parameters such as location, number, type, and survivability of given antenna systems. Each of these parameters can be varied to determine the overall optimal system. This thesis investigates computer numerical models to improve combat survivability for HF shipboard antenna systems. Future generations of ships will have low profile combat survivable antennas. Possible improvements for present ships might be the elimination of fragile HF antennas by exciting existing mast structures. Two mast configurations resembling an FFG-45 class ship are investigated for various heights: (1) a simplified rectangular column representing a forward mast, and (2) a tapered column containing more details and closely resembling an after mast. The masts are modeled by using surface patches and wire grids. Six computer models of the given masts are developed by the Numerical Electromagnetics Code (NEC). Average power gain, input impedance, and radiation patterns of driven antennas are presented and the results between surface patch models and wire grid models are compared for frequencies from 2 MHz through 16 MHz. It is seen that good performance is possible, for several different feed methods, when using existing mast structures for 2-16 MHz. Some feeding techniques and NEC modeling options that were tried were unsuccessful and yielded non-physical results.
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