государственный электротехнический университет «ЛЭТИ», 2 Первый Санкт-Петербургский государственный медицинский университет им. акад. И. П. Павлова

No abstract

Design principles of a new class of microwave thin film bulk acoustic resonators with multiband resonance frequency switching ability are presented. The theory of the excitation of acoustic eigenmodes in multilayer ferroelectric structures is considered, and the principle of selectivity for resonator with an arbitrary number of ferroelectric layers is formulated. A so called “criterion function” is suggested that allows to determine the conditions for effective excitation at one selected resonance mode with suppression of other modes. The proposed theoretical approach is verifiedusing thepreexisting experimental data published elsewhere. Finally, the possible application of the two ferroelectric layers structures for switchable microwave overtone resonators, binary and quadrature phase-shift keying modulators are discussed. These devices could play a pivotal role in the miniaturization of microwave front-end antenna circuits.

Determination of respiratory rate is a necessary task in assessing the state of health in humans. This review provides a description of modern devices used for recording and monitoring respiratory rate. The advantages and disadvantages of the principles of operation of these devices are discussed.