 
 <prompt> Wetin power gain represent? Based on di last question, write one context wey contain di answer. E fit be 1 - 20 sentences. Context: <response>: Antennas get different performance measures wey pesin go dey reason wen e wan select or design antenna for one particular use. The main ones dey relate to the direction wey the antenna dey face (as shown for the antenna radiation pattern) and the gain wey dey come out. Even for antennas wey dey omni-directional (or weakly directional), the gain fit still increase if dem focus more power for the horizontal directions, even if e mean say dem go reduce the power wey dem dey send go sky and ground. The antenna power gain (or just "gain") also dey consider the antenna efficiency, and e dey often the main figure wey dem dey look out for. 