Wireless and Continuous Strain Measurement of Rotating Helicopter Blades Using Implanted Backscatter Sensors

This paper proposes a wireless strain sensing system for model helicopter rotor blades using implanted backscatter sensors. Strain measurements from two sensors were continuously collected via dedicated subcarrier frequency backscatter channels. While coherent combining of two IQ streams improved packet error rate (PER) in low-speed rotations, it negatively affected performance at high speeds setting due to Doppler shift. Numerical simulations clarified the degradation mechanism and suggested a practical solution: using a single receiving antenna. This approach was validated through laboratory experiments.