A georadar, ground penetrating radar, ground penetrating radar, ground sounding radar, GPR or bottom radar is an instrument used to investigate or detect objects, structures, etc., below ground level.[1]​.

Georadar is a modern non-destructive technique, widely used by a very diverse group of professionals including agronomists, archaeologists, architects, criminologists, engineers, environmental specialists, foresters, geologists, geophysicists, hydrologists, land use managers, and soil scientists.

It is a non-invasive method of materials analysis based on the transmission of ultra-broadband electromagnetic waves in materials; in the range of 10 MHz to 2.6 GHz. A part of the electromagnetic wave is reflected when a boundary is reached between two materials with different electrical properties. The reflected signal is recorded at the source of the EM wave and displayed for the operator and frequently recorded for later analysis.

The applications of subsurface georadar as an ecological, non-destructive and high-resolution technique are widely documented, also due to the great versatility that characterizes it (e.g. water distribution systems[2]​). One of the challenges that this technique faces is being able to obtain information in greater depth than what is currently obtained, as well as methods of representing the data obtained that are easier to interpret.

Georadar is a relatively new technique. At the beginning of the century, Christian Hülsmeyer obtained the first patent on radar technology, in 1904. Six years later Gotthelf Leimbach and Heinrich Löwy applied this technology to locate objects buried underground.

Already in 1926, Dr. Hülsenbeck introduced the pulse radar system, which made it possible to significantly improve depth resolution, being a technique that is still widely used today. One of the first surveys using the georadar technique was carried out in Austria in 1929, where W. Stern measured the depth of a glacier.[3]​.

After this milestone, the georadar technique is abandoned for many years. It was not until after World War II that this technology was resumed, especially aimed at military applications such as locating tunnels in the demilitarized zone between North and South Korea.

Shortly thereafter, utility and construction companies became interested in georadar as a practical tool for locating conduction lines under city streets.[3] Another application that appeared around 1980 was the use of this ground-penetrating radar technology to explore, among others, water tables and salt deposits.