Fast Planar Near-Field Measurements of Reduced Angular Pattern Domains

Emerging 5G and Beyond wireless systems are putting the focus on millimeter-wave (mmW) and sub-THz antenna systems with multiple beams and a large number of elements yielding electrically large and complex radiant systems such as Reflective Intelligent Surfaces (RIS) or Massive MIMO panels. Characterization of those antennas may be unfeasible by means of conventional near-field techniques due to the required sampling schemes and high acquisition times. This work proposes a fast Planar Near-Field (PNF) technique based on sparse acquisitions. Singular Value Decomposition (SVD) techniques are employed to reduce the number of unknowns of the inverse problem and to design a non redundant measurement grid. By restricting the near-field to far-field transformation problem to a reduced domain of the antenna radiation pattern, a time-efficient characterization of the mentioned antennas is achieved. The proposed technique has been validated through numerical an measurement examples demonstrating its potential for fast and robust PNF measurements of narrow beam antenna patterns with large tilt angles.