A novel measurement method for respiration rate by electromagnetic frequency sweep

The non-contact measurement of the respiration rate of a subject offers several interesting applications in hospital as well as in domestic environments. The use of electromagnetic waves has been proved to be a feasible approach to this purpose. In this paper, authors present a novel measurement method, based on the transmission of a frequency sweep and the measurement of the reflection coefficient (S₁₁), to determine the respiration rate of the monitored subject without contact. The proposed method places itself at the half-way between continuous wave (CW) and ultra wide band (UWB) techniques, offering some advantages of both methods and improving its feasibility. Experimental tests have been carried out on voluntary subjects simultaneously measured with two reference systems in order to compare respiration frequency values. Results show a good correlation between the data measured during tests, proving that the proposed method is a valid approach to the issue of the noncontact assessment of the respiration rate both in clinical and domestic environments.