Hybrid ray optics and parabolic equation methods for radar propagation modeling

The use of parabolic equation (PE) methods has become very popular in recent years for modeling radar propagation effects in the lower atmosphere, especially for cases in which the vertical refractive index profile changes along the propagation path. The author presents a hybrid propagation model called the radio physical optics (RPO) model that uses a combination of ray optics (RO) and split-step PE methods to overcome the high computational burden of pure split-step PE methods. RPO considers four regions. At ranges less than 2500 meters and for all elevation angles above 5 degrees, RPO uses a flat Earth (FE) model. For the region beyond the FE region, a full RO model is used. The PE model is used for ranges beyond the RO region. For ranges beyond the RO region and heights above the PE region, an extended-optics (XO) method is used