The article discusses a method for accurately measuring permittivity using Time Domain Reflectometry (TDR) sensors. The researchers found that calibrating TDR sensors using a specific starting point determined by Heimovaara's method is crucial for accurate measurements, especially at low permittivity values. They recommend adopting this method as a standard practice. The study also highlights the importance of placing the starting point slightly forward of the waveform bump to avoid errors in measuring travel time in layered media. Additionally, using long cables to connect sensors can introduce errors due to temperature changes, but these errors can be minimized by using software to track the sensor head.