VHF/UHF Propagation by Diffraction - Calculation by Numerical Integration,
COMMUNICATIONS RESEARCH CENTRE OTTAWA (ONTARIO)
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Since precise mathematical solutions of the diffraction problem exist only for simple shapes knife edge, cylinder, sphere, most methods of estimating path loss idealize the terrain as a small number of such shapes, and then apply the solutions to those shapes. The method proposed here, instead of using solutions already worked out, applies approximate diffraction theory to a terrain model that retains most of the complexity of the real terrain, and finds a numerical solution to the diffraction problem for each particular transmission path profile. The method is to find the radiowave field as a function of height above each terrain point by integrating over the field above the preceding terrain point, using Huygens principle. The integration is done not only for direct rays, but also for earth-reflected rays. Such a detailed calculation is demanding of computer time, but an attempt is being made to keep the computer time short enough so that the calculation can reasonably be done on line.
- Radiofrequency Wave Propagation