The stratosphere-troposphere radar PROUST (prototype de radar pour l'observation en UHF de la stratosphère et troposphère) is located at Saint Santin, France (44°39′N; 2°12′E), a place devoted to the French ionospheric incoherent scatter facility whose frequency is 935 MHz. The use of this equipment as stratosphere-troposphere radar has required important modifications of the transmitting and receiving systems, which have been planned in several steps. In a first one, the radar works in a bistatic mode with a 600-m height resolution, allowing measurements in the altitude range 3–10 km. The first results presented here have been obtained with this configuration during two campaigns. In the first one, observations can be interpreted in terms of lee waves; in the second, an intense turbulence activity associated with a high-altitude temperature inversion is observed. In this last case, the oscillations observed in the vertical wind are consistent with trapped gravity waves generated by a decaying turbulence in a stratified medium. In a second step, now operating, a 30-m height resolution has been implemented and will allow a better understanding of these phenomena. In its final version, the PROUST radar will operate in a monostatic mode that will permit to extend the observations up to 15 km.