Explain why reception for high frequency band is better during night time.

Explain why reception for high frequency band is better during night time.
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Answer :

In sky wave propagation, the transmitted signal travels into the upper atmosphere where it is bent or reflected back to earth. This bending or reflection of signal takes place due to the presence of a layer called as ionosphere in the upper atmosphere. There are four main ionospheric layers F2, F1, D, E in the descending order. At night the F1 and F2 layers combine to form one layer and the lower two layers D and E disappears. As the lower layers are absent, the absorption of the signal does not take place, which was taking place during the day time. This improves the strength of the reflected signal and hence the reception for high frequency band is better during night time.

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