Which frequency band shows decreased ground wave range as frequency increases?

The frequency band that shows decreased ground wave range as frequency increases is indeed the high frequency band. Ground wave propagation involves the transmission of radio waves along the surface of the Earth, and it is most effective at lower frequencies. As frequency increases within the radio spectrum, the ability of ground waves to follow the curvature of the Earth diminishes. This is due to several factors, including increased free-space loss and the tendency of higher frequencies to radiate more energy into the atmosphere rather than along the surface.

In the case of high-frequency signals, which typically range from 3 to 30 MHz, they tend to be more affected by the curvature of the Earth, and as the frequency increases further into the very high frequency (VHF) range, ground wave propagation capabilities decrease significantly. Higher frequencies are more likely to propagate via line of sight or through ionospheric reflection, leading to shorter effective ranges at ground level as compared to lower frequencies like medium and low frequencies, which can travel longer distances along the ground.

Thus, the understanding of these propagation characteristics is crucial for effective communication strategies depending on the frequency band being utilized.