System aspects of clear air propagation above 40 GHz

Communication links operating at frequencies above 40 GHz may be modeled by computer programs which treat both the atmosphere and communication hardware of the system in an integrated fashion. Absorption by atmospheric gases and turbulence effects are considered. Link degradations due to seasonal variations are treated. Absorption by molecular oxygen and water vapor causes dispersive signal attenuation, phase delay, and noise due to random atmospheric emission. These quantities may be predicted for specific frequency bands and atmospheric conditions by employing a computer program for ray tracing. The characteristics of the atmospheric transfer function are of importance to questions of modulation distortion in high data rate systems. The atmosphere is viewed as an additional signal filter of the communication channel and the resultant signal distortion is quantified by predicting bit error rate degradation.