Near line of sight is also known as non line of sight used to describe radio transmission across a path that is partially obstructed mostly by a physical object in the Fresnel Zone.

When a RF wave reflects back from a tall object or a low object while it travels between two points a duplicate of the original signal is being created. The distance travelled by both the distance the signals is different and therefore they arrive at different time at the same destination. The time difference between the propogation leads the signal to overlap and merge into a single distorted signal at the receiving end. This clashing between the original signal and the duplicate signal leads to multipath interference.

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