Modern day displacement sensors can measure displacement due to cracks in concrete structures at most in 2-dimensions, and can mainly measure the displacements very close to the sensor itself. This is an issue since the sensors are very small, require constant power, and are wired. Radio Frequency (RF) sensors however can measure the distance between each other by sending signals with different properties. These sensors should be able to measure displacements in three dimensions, allowing for a more holistic view of the stresses acting on the structure. Additionally, these sensors should require no tethering or power source, allowing for easy installation and data collection throughout the entire structure. Our research focuses specifically on finding a relationship between the phase of the waves extracted from the sensors to the displacement between them. Via static and dynamic testing, we emulate the formation of cracks by changing the distance between two concrete slabs in which RF sensors are embedded. The experiments indicate clear correlation between features of the transmitted signal and minute displacements. Experiments also indicate that significant changes in the environment (temperature, humidity, pressure) can be confounding factors, and further experiments and data analysis are being performed to quantify environmental effects. In conclusion, RF sensors are the future of smart structures in our urban environment, as they can help detect the failure of a structure before irreversible damage is done, and save lives throughout the world.