Tropospheric Attenuation: a Challenge for Future Earth-Space Communications Systems

In approximately 60 years, Earth-space communications have evolved from early broadcasting systems to the modern complex interactive ones able to deliver worldwide broadband coverage. This was made possible by the gradual transition of carrier frequencies from the S band (2-4 GHz) to the Ka band (26.5-40 GHz), which is still partially taking place. Unfortunately, the increase in the carrier frequency is also accompanied by the growing impact of the troposphere, which induces several negative effects, attenuation being the most detrimental one. If the troposphere already poses clear limitation to modern Earth-space communications, even more it will to future systems, which are foreseen to operate at even higher carrier frequencies. This contribution discusses such challenges, specifically targeting next generation Earth-space communication systems operating at V band (40-75 GHz), W band (75-110 GHz) and, possibly, even up to the sub-THz band.