Investigation of Near-Field Contribution in Shooting and Bouncing Rays for Installed Antenna Performance on a Simple Platform

The near-field contribution in the high-frequency method Shooting and Bouncing Rays (SBR) is investigated for installed antenna performance. Three SBR solvers, the in-house solver SIENT and two commercial solvers, are compared to a commercial full-wave solver. SIENT and one commercial solver have an option to disable near-field effects, which allows the strength of these effects to be investigated. The last solver also includes near-field effects. The results indicate an increase in accuracy when including near-field effects. The most notable difference in the far-field phase and the induced surface current are obtained for the in-house solver. Improvements for the surface current density is seen close to the antenna. On the tested platform, the difference in gain is not as notable but it is overestimated for both the in-house solver and the commercial solvers when excluding near-field terms.