Electromagnetic Simulation of a CATR for Digital Twin Development

Abstract

This thesis presents the development of a simulation model of an Over-The-Air (OTA) Compact Antenna Test Range (CATR) chamber as an initial step toward a digital twin of Ericsson’s OTA environment. The work investigates how scattering objects and different chamber configurations affect Quiet Zone (QZ) performance. Electromagnetic simulations were performed using Physical Optics (PO) and Method of Moments (MoM) formulations to evaluate field distributions and to study QZ characteristics such as amplitude, phase, and ripple variations. The results show that the model can reproduce some qualitative features of OTA chamber behavior, particularly QZ degradation due to scattering objects and reflector geometry. Comparison between PO and MoM highlights limitations of the PO approximation, especially where edge effects dominate, leading to discrepancies in field distribution and ripple behavior near reflector edges. Despite these limitations, the model enables useful comparative analysis of chamber configurations. Variations in reflector geometry and the presence of scattering objects consistently affect QZ uniformity, influencing both amplitude and phase distributions. The study also indicates that improvements from serrated reflector edges are mainly linked to an increased effective reflecting area. Overall, the simulation framework provides a first modelling step toward a future digital twin of the OTA chamber. While absolute accuracy is limited by the current electromagnetic formulation, the model is useful for studying relative QZ degradation and guiding future improvements in chamber design and simulation fidelity.