A highly sensitive wireless passive radio frequency strain transducer is designed and developed based on a patch antenna loaded with an open loop. A novel idea of utilizing a cantilever at the gap of the open loop significantly improves the sensitivity of resonant frequency shifts. The ground plane allows the sensitivity of the sensor to be independent from the applied surface. A proof-of-concept prototype is fabricated and the measurements successfully validate the operation principle. Index Terms — strain stress sensor, RF transducer, wireless passive sensing.