On the ray tracing block of a sky wave over-the-horizon radar simulation tool

A simulation tool of a sky wave over-the-horizon radar performance and detection process includes many stages based on different models, which creates a synthetic searching scenario as a first step followed by a digital signal processing to detect and locate a potential target. The whole process involves several concatenated physical mechanisms which depend on OTHR specific properties. They can be modeled as quasi-independent blocks to analyze synthetic scenarios in order to define the radar's characteristics and range of operation which are essential when selecting radar's operating parameters in order to achieve the best performance. In this work a sensitivity analysis of the ray tracing block is performed. This block is implemented as an independent block in the simulation tool and estimates the signal propagation path with an adapted Jones & Stephenson ray tracing code. This code has options for: (1) the electron density profile, which can be chosen from analytical models or the IRI-2016 model, (2) the Earth's magnetic field from the IGRF-12 model, which can be turned on and off, and (3) collision frequencies, which can also be turned on and off. From this ray tracing we obtain the two-way delay of the signal travelling between the transmitter and the target, the ground range distance and azimuth relative to the transmitter. The sensitivity analysis is carried out analyzing this block output's variation as a consequence of changes in its main input factors. This study is useful to dimension features and elements of a real radar, and also to determine the needs of in-situ ionosphere sounding.