When the engineer adjusted the directional antenna, it was found that when the antenna was placed far from the other antenna, the signal would drop, and then the signal would increase slightly. What caused this increase in signal?

When the engineer adjusted the directional antenna, it was found that when the antenna was placed far from the other antenna, the signal would drop, and then the signal would increase slightly. What caused this increase in signal?
A . Signal reflection
B . Frequency harmonics
C . Sideband
D . Sidelobes

Answer: D