Backscatter-Based Wireless Sensing System for Multi-Channel Complex Impedance Measurements

We present a novel work that implements the principle of backscatter communication to enable multiple sensing with a single antenna connected to an SP4T switch. It is demonstrated that data from multiple sensors can be plotted in real-time directly on the IQ pattern of the received signal. Clustering classification is implemented for automatic identification on the IQ diagram of various sensor-related impedance states. A practical experiment based on the use of a software-defined radio on one side and a backscatter node with two different passive sensors demonstrates the proof of concept.