Detection of dilute inclusion concentration in polymer metal composite using microwaves

A measurement technique to estimate dilute concentrations (1-5%) of metal inclusion in an inert dielectric is presented. Bulk permittivity of polymer metal composites with aluminium powder (1-5%) in epoxy indicated very small variation for the dilute mixtures. Reflection measurements from composites with small variation in bulk permittivity, Δε≈1 indicated an appreciable change in phase. Experimental results demonstrate the feasibility to detect the change in inclusion concentration of dilute mixtures using microwave measurements.