On the ground wave propagation over a cliff with finite ground parameters

Wang, Haiyin (1992) On the ground wave propagation over a cliff with finite ground parameters. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (8MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

The characteristics of the ground-wave propagation over a cliff are investigated using both the residue and the compensation methods. The two methods are reviewed and compared. The theorical analysis for the ground wave propagating from sea to earth is presented in detail. The residue method employes Fourier transform and Green theorem, while the compensation method employes the surface impedance technique. The analysis of the two methods are reintroduced in a more clarified way. The differences between the assumptions of the two methods are identified and comparisons of the relative results are illustrated. -- The flat-cliff approximation is used to obtain the terrain coefficient so that the problem can be solved when the antennas on the cliff top are close to the cliff edge. The final expressions of terrain coefficient and field distribution over the cliff as well as the sea are presented. -- An approximate analysis expression, called the two terms approximation, is presented in this work to calculate terrain coefficient. The two terms approximation is based on the flat-cliff approximation of Green theorem method. It simplifies the numerical calculation of the problem. -- Graphs are shown in this work to describ the fields changing over the ocean and over the cliff for the transmitters on the cliff and on the ocean separately. The numerical results are in a good agreement with available literature data. -- The expressions and results given in this work can be used to determine the optimum location and height of an antenna over a cliff. -- Presently, a prototype bistatic radar system which uses ground wave propagation for over the horizon target detection is being built on a cliff at Cape Race, Newfoundland. The radar has a log periodic array antenna as the transmitter and a linear array as a receiver. The results, data and the program given in this work are very helpful in designing new groundwave radar antennas on the cliff since the program can be used to determine the optimum location and height of the antennas for both the source and the receiver.

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