Abstract: According to an aspect there is provided a sensor circuit for use in a body and for communicating measurements of an in body property to a signal analyzer, the sensor circuit comprising a resonant circuit that is responsive to a first radio frequency, RF, field to receive a carrier signal, the resonant circuit having: a first transducer, wherein a first electrical property of the first transducer is dependent on the in-body property, and a second transducer, wherein a second electrical property of the second transducer is dependent on a second pulsed field; wherein the carrier signal received by the resonant circuit is modulated by changes in the first electrical property due to the in-body property and changes in the second electrical property due to pulses in the second pulsed field.

Abstract: A vital sign monitoring device (10) includes a radio frequency (RF) loop coil (12) that is resonant at both a low frequency and a high frequency that is different from and higher than the low frequency. An annular Faraday shield (18) is arranged to shield the RF loop coil. An oscillator circuit (22) is connected to the both lower and higher oscillation frequency determining RF loop. Readout electronics (24) are connected to measure an electrical response of the RF loop coil energized by the voltage source at both the low frequency and the high frequency and to: extract at least one signal component of the electrical response at the low frequency; extract at least one signal component of the electrical response at the high frequency; and generate vital sign data using both the at least one signal component of the electrical response at the low frequency and the at least one signal component of the electrical response at the high frequency.