Experimental estimates of the value and temperature dependence of the air-humidity quadratic component of the atmospheric water-vapor absorption coefficient in the frequency band of 140-410 GHz

The water-vapor absorption of radiowaves with frequencies of 138, 247, 260, and 340 GHz was measured over a near-earth path with a length of 1 km. The obtained experimental data together with earlier measurements in atmospheric radio windows with centers near 220, 340, and 410 GHz (carried out at the Radiophysical Research Institute) were used to estimate the value and temperature dependence of the air-humidity quadratic absorption component with allowance for the known laboratory-experiment data on its linear component.