Reliability of discerning humans using microwave polarisation and diffraction phenomena

Sammanfattning: Presented here is an examination of the feasibility to utilise basic microwave phenomena for reliable human discernment. Being able to distinguishing a person from other objects is essential around society. For example, near railway tracks where lives could be saved if a system could alert the driver. Microwave technologyhasseveralbenefitsoverotherdetectionsystems. Forexample, itallowscompletelyanonymous detection. Microwavesarealsoinsensitivetodarkness,brightsunlight,andrain. Theprinciplesofantenna polarisation and diffraction phenomena have been investigated with the purpose of locating parameters that can reliable discern a human. By modelling analysis, calculations, examination of related work and measurements, it has been seen that a large number of parameters affect the diffracted fields that occurs around an object under some circumstances. For impartial comparison and the ability to change single parameters at a time, a human phantom has been investigated and constructed. Modelling analysis has been performed in order to visualise how the diffraction changes due to the relationship between object circumference and wavelength, and also due to the dielectric properties of the object. The diffracted fields caused by two different frequencies has been compared, giving a difference signal that in a certain range is potentially reliable for human discernment. Analysis of the measurements conducted in an anechoic chamber show some similarities between the real measurements and the modelled scenarios, and also that the phantom was a successful substitute for a pair of human legs.