Electromagnetic modelling of the SKA-LOW AAVS1.5 prototype

The numerical modelling of the Square Kilometre Array (SKA) Aperture Array Verification System Version 1.5 is discussed. The role of this SKA prototype is placed within the perspective of the overall SKA project. The dual-polarized log-periodic SKALA4.1 antenna elements comprising a station are briefly described, along with some considerations regarding the station. Computational simulation aspects are considered, and preliminary results shown. An appraisal of the implications for station-level calibration concludes the paper

Optimizing Processing Time of Radio-Astronomy Antenna Simulations using FEKO

The far-field pattern of a geometrically large and complex antenna used in low-frequency radio astronomy is computationally expensive to simulate on electromagnetic simulators, such as FEKO. For example, one station of the Square Kilometer Array, which consists of 256 log-periodic antenna elements, will take years to simulate using the full CAD model for the full operational frequency band. This paper focuses on reducing the simulation time for a single antenna element by simplifying the simulation model, thus decreasing the number of unknowns that have to be solved in a simulation. An iterative process for optimizing the simplification of such an element is described, while keeping the reflection coefficient within 1 dB absolute mean deviation of the measured data. After four iterations, the amount of unknowns to be solved, which includes the number of triangles and segments, was reduced from 29,307 to 11,991. This decreased the computation time by 86.5%, making array simulations feasible. Using the techniques described in the paper, other antenna constructions can benefit from it and be simulated more efficiently