The Ku-band is 12-18 GHz portion of the electromagnetic spectrum in the microwave range of frequencies and this frequency is primarily used for satellite communication.
However, there is a disadvantage of Ku-Band system. As this is higher frequency than 10 GHz in heavy rainfall areas, a noticeable degradation occurs, due to the problem caused by and proportional to the amount of rainfall (known as "rain fade"). This problem can be mitigated, by deploying an appropriate link budget strategy when designing the satellite network, and allocating a higher link margin and power to compensate rain fade loss.
Another way to reduce this rain fade, we can use hydrophobic coating on antenna dish. Hydrophobic literally means of "water fearing" and in this context, it means that the water on the antenna surface is in beads rather than in sheets. Water which appears will absorb much of the signal, leading to high losses. If water is in beads, the energy will be slightly diffracted because the water droplets have dimensions much less than a wavelength at these frequencies.
This Hydrophobic things can be illustrated work like a Lotus effect. The Lotus effect refers to self-cleaning properties that are a result of very high water repellence (superhydrophobicity), as exhibited by the leaves of the lotus flower. Dirt particles are picked up by water droplets due to the micro and nonoscopic architecture on the surface, which minimizes the droplet's adhesion to that surface.
The standard measure of hydrophobicity for a surface is the contact angle between that surface and a water droplet sitting on it: as determined be a contact goniometer. Tha angle is measured at the base of the water droplet as illustrated in the inset.
A surface is generally considered to be hydrophobic if the contact angle is greater than 90° . By this measure, Teflon, with a contact angle of 107° is considered hydrophobic.
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