US Patent 11675101 Determining presence and depth of materials in the earth

A method for determining depth of a material is disclosed. The method includes transmitting a signal from an antenna at a location. The signal includes a fundamental frequency and the signal penetrates ground under the location. The location is selected to locate a material at a depth under the location. The fundamental frequency matches a known resonant frequency of a resonant atom of a molecule of the material. The method includes detecting a reflected wave on the antenna, determining a time difference between transmission of the signal and detection of the reflected wave on the antenna, and determining the depth to the material based on the time difference and a reflected velocity corresponding to the resonant atom.