Which of the following is NOT a factor that affects the range of radio equipment?

Radio communication range is influenced by several physical and environmental factors. Weather can impact radio waves with phenomena such as rain attenuation, temperature inversions, and atmospheric conditions affecting signal propagation. The type of antenna used plays a crucial role in determining how effectively a signal is transmitted and received; different antennas have varying directional patterns and gain characteristics. Additionally, the location of both the transmitter and receiver can significantly affect the range, as physical obstructions like buildings and terrain can hinder signal strength.

Human error, while it can lead to improper setup or operation of radio equipment, does not inherently change the physical properties or characteristics of the radio signals themselves. Therefore, it is not a direct factor affecting the range of radio equipment in the same way that environmental and physical factors are. This distinguishes human error from the other options, making it the correct choice as the factor that does not affect radio equipment range.