Földhullámú

Földhullámú is a Hungarian term that translates to "earth wave" or "ground wave." In the context of radio communication, it refers to the propagation of radio waves that travel along the surface of the Earth. This type of propagation is most effective at lower frequencies, typically in the very low frequency (VLF), low frequency (LF), and medium frequency (MF) ranges.

Ground wave propagation is influenced by the electrical properties of the Earth's surface, such as its conductivity and permittivity. As the radio wave travels along the Earth's surface, it induces currents in the ground, which in turn absorb some of the wave's energy. This absorption leads to a decrease in signal strength with distance. Consequently, ground wave range is limited, especially at higher frequencies.

Despite its limitations, ground wave propagation is valuable for certain applications. It is commonly used for long-distance radio broadcasting, maritime communications, and for navigation systems. The predictable nature of ground wave propagation allows for reliable communication over moderate distances, particularly during the day when ionospheric propagation can be less stable. The effectiveness of ground wave propagation is also generally better over saltwater than over dry land due to the higher conductivity of saltwater. Understanding the characteristics of földhullámú is crucial for designing and operating radio systems that rely on this mode of propagation.