Simulering av radarvågutbredning – Utveckling av absorberande randtekniker för den paraboliska vågekvationen

This thesis explores two different methods to simulate radar propagation by solving the Paraboliv wave equation (PWE): the Finite Difference (FD) method with the Crank-Nicolson (CN) scheme and the Split-Step Wavelet (SSW) method. A central part of the thesis is to implement absorbing boundary conditions at the top boundary of the computational domain to simulate an infinite upper boundary. The method used for this is the Perfect Matched Layer (PML). The methods are evaluated on their computational ability, convergence, accuracy, performance with the PML and ability to handle different atmospheric conditions. The FD, CN method shows high accuracy, but this comes at a cost of lower computational efficiency, and the SSW method can use coarser grids and faster computation times, but does not reach the same accuracy. The PML gives a satisfactory absorption of the signal when using a well tuned damping function. A cubic damping function is shown to perform well if the parameters are tuned correctly. The method choice depends on the priority between computational speed and accuracy.