Signal attenuation due to rain is the primary source of outages on earth-satellite radio links operating above 10 GHz. Measurements of the durations of rain fades are also useful in assessing link performance since the effect of many short outages is clearly different than that of fewer long outages. In this paper the authors present a set of measurements of the number and duration of rain fades measured at 19.04 GHz along an earth-satellite path with 18.5 degree elevation. Since rain attenuation is seasonally dependent, one would expect some seasonal variation in at least the rate of occurrence, and possibly the durations of rain fades. This paper briefly examines this dependence. Another factor affecting the performance of earth-satellite RF links is the distribution of time intervals between rain fades, called here `interfade intervals'. If the probability of short interfade intervals were high, this could adversely influence the link performance for services with long holding times. This paper presents measured distributions of these intervals.

Relationships between rain and ice attenuation and depolarization at 19 GHz have been determined for linear incident polarizations ± 4 and\pm 8\degfrom vertical. These relationships are based on measurements made using beacon transmissions from a COMSTAR satellite. A technique is used to bound depolarization magnitude at any incident polarization from a depolarization magnitude measurement made at another polarization. This technique makes use of previous observations that depolarization is minimal at vertical and horizontal incident polarizations. The bounds are compared with the results from the COMSTAR measurements.

Cumulative attenuation distributions for one year and relationships between attenuations at 19 GHz and 28 GHz are presented for an earth-space propagation path terminating at Crawford Hill, New Jersey. An example from the distributions indicates that 20 dB attenuation was exceeded for 0.012% of the year at 19.04 GHz and for 0.06% at 28.56 GHz. For both frequencies the polarization was linear and oriented 21° from vertical at the receiver. When the attenuation at 19 GHz was less than 20 dB, the attenuation in dB at 28 GHz averaged 2.1 times that at 19 GHz. This ratio was lower at higher attenuations.