Characteristics of a radio link in the 55 to 65 GHz range

The long-term variability (i.e., greater than hundreds of seconds) of the transfer function for a radio link in the 55 to 65 GHz range is examined by computing the differential attenuation and differential phase with respect to changes in pressure and temperature. The computed values for the differential attenuation and phase for a 3 km path are on the order of 0.06 dB and 0.13 rad, respectively, for a 5 percent change in temperature and a 1 percent change in pressure. This indicates that in some applications an equalizer may not be necessary. The expected time variations in the transfer function are estimated from experimental measurements of atmospheric changes. The time variability of the transfer function shows a high degree of correlation with the time variability of the air density.