Statistical Tolerance Analysis of Biomedical Near-Field Focused Antenna Arrays

In this contribution, Near-Field Focused Arrays (NFFAs) are considered, able to concentrate/receive the power density at/from specific points located in their near zone. Although satisfactory solutions could be determined through optimisation procedures, errors must be always considered in the practical implementation of any engineering system, in order to meet reliability and safety requirements. In this contribution, biomedical applications are mainly considered, such as hyperthermia and medical imaging, where errors potentially affecting the patient safety and the reliability of diagnostic results must be adequately considered. In particular, following the reference literature, the most common errors in antenna arrays are considered, namely excitation and element failure errors. These are modelled as appropriate random variables, which can strongly distort the structure of the reference electric field, leading to an increase in the secondary lobes and providing also errors in the position of the focal points. A parametric analysis is performed, with respect to the errors strength, of some characteristic parameters of the squared magnitude of the electric field, which is directly related to the radiated/received power density.