A near-field sensor method and device for obtaining cardiovascular information is disclosed. A transmission-line aperture arrangement configured to guide electromagnetic waves and emit near-field fringing energy, is placed near the skin. The transmission line is excited at a narrow-band Gigahertz frequency. The near-field fringing energy emitted by the sensor device penetrates at least partially into the skin and underlying blood vessels, and this energy is partially absorbed and partially phase shifted in a time varying manner according to the changes in physiology of the skin. The status of the sensor device is monitored over a plurality of time intervals, and changes in both the phase and the amplitude of the signals passing though the transmission line are used to determine the cardiovascular information such as heart rates. Various transmission-line configurations, and various reference transmission-line methods to reduce low-frequency noise, are also discussed.
