A Near-Field Measurement Setup Using an Array of Optically Modulated Scatterers

In this paper, the design and implementation of a near-field (NF) measurement bench is discussed. The bench is based on the well-known modulated scatterer technique (MST). A low-cost optically modulated scatterer (OMS) probe based on a commercial-off-the-shelf (COTS) photodiode has been conceived and implemented. The probe itself is a short dipole that has been optimized for minimum scattering. Due to invisibility of the optical fiber to the electromagnetic field in the microwave range, making measurement using the OMS probe is essentially perturbation free. The performance of the implemented OMS probe has been validated by measuring known electric field distributions. A probe array is also developed to reduce delays associated with probe movement occurring in near-field planar scanning.