Results of the balloon measurements of the stratosphere radiothermal radiation at 5 mm

Original microwave radiometer with double frequency conversion developed for remote thermal sounding of the stratosphere up to 40 km is described. Radiometer operating at the slopes of two oxygen lines with resonant frequencies 57.612 and 61.151 GHz has 6 channels with bands of 3 to 150 MHz and sensitivities of 0.6 to 0.09 K, respectively. Results of two balloon flights (one with nadir microwave sounding and another with sounding at the 15° zenith angle) are presented.