Measurement of magnetic field components using a single passive SAW magnetic sensor

SAW sensors have gained substantial consideration over the years due to their valuable characteristics of having a miniature size, simple structure, and higher sensitivity. SAW sensors have been developed for a wide range of applications to measure numerous kinds of measurands including magnetic fields. In this paper, an innovative idea of simultaneously measuring multiple magnetic field components using a single multi-port reflective delay line SAW device has been presented. This is in contrast to the conventional SAW magnetic sensors that can measure only a single field component along their sensitive axis. The sensor uses Giant Magnetoimpedance (GMI) amorphous wires as a magnetic sensitive element which are integrated externally with the reflective ports of the SAW device as the magnetic sensitive load impedances allowing easy replacement of GMI element in the sensor for different sensitivity range requirements. The sensor design supports both active and Radiofrequency (RF) powered passive operation and exploits Time Domain Sampling (TDS) for interrogation making it suitable for wireless sensing of magnetic field components in applications where conventional magnetic sensors are not a good alternative. The obtained experimental results using two different variants of the sensor with operating frequencies of 100 MHz and 1 GHz demonstrated successful measurements with higher accuracy which validated the idea of simultaneously measuring the magnetic field components using a single SAW device.