Describe the concept of a radiation pattern and how antenna height affects it.

• A. The radiation pattern shows the signal strength over time; height has no effect.
• B. The radiation pattern shows signal strength versus direction; increasing height generally improves horizon coverage and can alter nulls and lobes.
• C. The radiation pattern only indicates impedance; height determines color.
• D. The radiation pattern is fixed and cannot be altered by height.

Answer: (B)

A radiation pattern shows how the antenna’s radiated power varies with direction, basically a map of signal strength or gain around the antenna rather than a time-based waveform. Height above the ground matters because the earth acts as a nearby reflector and changes how the direct and reflected waves combine. When you raise the antenna, the balance between the direct and ground-reflected waves shifts, which reshapes the vertical pattern by moving the directions of maxima and minima (the lobes and nulls) and often pushing more energy toward higher elevation angles. This generally improves horizon coverage because more of the energy reaches distant receivers over the curved surface of the Earth, and it can also alter where the strongest directions lie. In practical terms for radios like the AN/PRC-160 and AN/PRC-163, mounting the antenna higher tends to enhance long-range LOS reach and change the elevation pattern in ways that can favor the links you’re trying to establish.