Applying the nonuniform FFT to the parabolic equation split-step algorithm for high frequency propagation modeling

A popular approach to modeling electromagnetic wave propagation in the troposphere is to use the Fourier split-step algorithm to solve the parabolic equation (PE) by marching over range steps. In each step a Fourier transform is made to the frequency domain followed by a multiplication of the frequency-domain operator. The result is then transformed again to the space domain and is followed by a multiplication of the space-domain operator. The PE algorithms provide a fast and efficient numerical solution to most long-range propagation problems. Some limitations of this technique are that it neglects the backscattered field and is accurate only for waves propagating near horizontal directions. In this paper, we show a new method that implements the nonuniform fast Fourier transform in the Fourier split-step algorithm to solve the parabolic equation.