The effects of dielectric loss and tip resistance on resonator Q of the scanning evanescent microwave microscopy (SEMM) probe

Scanning evanescent microwave microscopy (SEMM) has significant potential for measuring dielectric properties. The loss tangent appears in a linear term in the relation between frequency shift and resonator quality factor (Q) shift, but the coefficient of this term was not generally known. The derivation of an analytic expression for the coefficient is presented here; good agreement is seen with simulations. In addition, it is shown that the resistance of the evanescent microwave probe (EMP) tip gives rise to a quadratic term in the expression for Q shift. © 2008 IOP Publishing Ltd.