Phase-Coherence in a Shallow Water Waveguide
A fundamental property in determining the response of an array is the spatial coherence across the array. Modelling the shallow-water waveguide in terms of normal modes, the phase-coherence factor among modes is known to control the model interference term. This factor is defined using a generalized van Cittert-Zernicke theorem. The resulting expression for the phase coherence is calculated from a spatially-extended single-frequency source, each source element generating m modes. Since single source elements are assumed to radiate incoherently, the complex degree of coherence from an extended source is calculated without the explicit use of an averaging process. Results for a top-to-bottom array are presented for different bottom types, source locations, and sea-surface irregularities.
KeywordsDepth Function Coherence Function Phase Coherence Partial Coherence Vertical Array
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