Channel modeling using the parabolic equation for RF communications

A method that uses the parabolic equation (PE) model to characterize the transmission channel for wideband waveforms is discussed. The results presented use the Advanced Propagation Model (APM) developed by the Atmospheric Propagation branch at the SSC Pacific which utilizes the split-step Fourier algorithm to solve the PE wave equation for a continuous wave (CW) source. To determine the channel response for a given geometry and environment, an approach used to determine the proper frequency sampling to resolve the multipath components will be discussed. The channel impulse response is computed for an ideal case having a direct and reflected path with a known solution, as well as for examples using ducting, terrain, and a surface-based duct measured off the coast of southern California. An example is provided to demonstrate how this method can be used to characterize the time spreading of a waveform and how it can be used to assess the impact of channel-induced intersymbol interference (ISI).