A directional antenna focuses its radiation density in a specific direction. Due to its directivity, interfering transmitters placed outside of primary or secondary lobes are muted, and the antenna increases its reach in beam direction. Consequently the antenna radiates in one direction only, with an opening angle of e.g. 80°.
Antenne gain: The gain of an antenna stands for the amplification of its transmission energy. This gain is achieved by the transmission energy being focused by the antenna in horizontal and/or vertical direction