1 A METHOD of “WEAK RESONANCE” for QUALITY FACTOR and COUPLING COEFFICIENT MEASUREMENT in PIEZOELECTRICS Alex V. Mezheritsky, “A METHOD of “WEAK RESONANCE” for QUALITY FACTOR and COUPLING COEFFICIENT MEASUREMENT in PIEZOELECTRICS”, adapted from the manuscript submitted to the journal IEEE UFFC, Jan. 2005. Abstract - In the absolute-immittance spectrum of a piezoelectric resonator (PR), if the relative resonance- antiresonance frequency interval of a high intensity resonance is basically determined by the coefficient of electromechanical coupling (CEMC), the relative resonance - antiresonance frequency interval of a low intensity resonance with the resonance-antiresonance attenuation less than 15 dB, regardless of the reason, is determined by the quality factor Q of the resonance, and its intensity is proportional to CEMC. The technique for the quality factor and CEMC determination based on the “weak resonance” (WR) concept has been formulated and then applied to low-Q and/or low-CEMC piezoelectrics, including the initial stage of piezoceramics polarization, to piezotransducers under electrical or mechanical loading with maximum efficiency. The WR - method allows to determine the quality factor on PRs under specific conditions, such as: arbitrary PR shape resulting to a broken frequency spectrum; PRs with an extremely large or extremely low electrical capacitance; at high-order PR harmonics; electrodeless piezoelements under mechanically contactless excitation; determining the local thickness - mode material quality factor value and its distribution along the surface of a thin electrodeless piezoplate – all where the traditional methods appear a poor performance or do not work at all. Keywords: piezoelectrics, piezoceramics, coefficient of electromechanical coupling, quality factor. Author: A.V. Mezheritsky e- mail: mav5@optonline.net ( CC: amezheritsky@ieee.org )