Editing Null fill (section)

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'''Null fill''' in [[radio engineering]] is used in [[radio]] [[Antenna (radio)|antenna]] systems which are located on [[mountain]]s or tall [[tower]]s, to prevent too much of the [[signal]] from overshooting the nearest part of intended coverage area.  [[phase shifting|Phasing]] is used between antenna elements to take [[electrical power|power]] away from the [[main lobe]] and electrically direct more of it at a more downward angle in the [[vertical plane]]. This requires a [[phased array]]. Changing the relative power supplied to each element also changes the [[radiation pattern]] in this manner, and often both methods are used in combination.