What is the difference between VHF and UHF?

VHF (Very High Frequency) and UHF (Ultra High Frequency) are two different frequency ranges in the radio spectrum, each with its own characteristics and applications.

VHF (Very High Frequency) covers the frequency range of 30 MHz to 300 MHz. Some common uses of VHF frequencies include FM radio broadcasting, television broadcasting, marine and aviation communication, and amateur radio. In the context of amateur radio, the most popular VHF band is the 2-meter band (144-148 MHz), which is widely used for local communication, repeaters, and various digital modes.

UHF (Ultra High Frequency) covers the frequency range of 300 MHz to 3 GHz. UHF frequencies are used for television broadcasting, mobile phones, GPS, Wi-Fi, Bluetooth, and various other communication systems. In amateur radio, the most popular UHF band is the 70-centimeter band (420-450 MHz), which is used for local communication, repeaters, satellite communication, and digital modes like DMR, D-STAR, and Yaesu System Fusion.

The main differences between VHF and UHF are related to their propagation characteristics and the way radio waves behave at these different frequencies:

• Propagation: VHF signals generally travel farther than UHF signals under similar conditions due to their longer wavelengths. VHF signals can propagate via ground waves, which follow the curvature of the Earth, and are also more likely to be reflected by the ionosphere, enabling long-distance communication.
• Line-of-sight: Both VHF and UHF signals are primarily line-of-sight, meaning they travel in straight lines and are affected by obstacles like buildings, hills, and trees. However, UHF signals are more easily absorbed by obstacles and have shorter wavelengths, which makes them more susceptible to reflection, diffraction, and multipath propagation effects.
• Antenna Size: Antenna size is related to the wavelength of the radio signal. Since VHF wavelengths are longer than UHF wavelengths, VHF antennas are generally larger than UHF antennas for the same level of performance.
• Penetration: UHF signals can penetrate obstacles like walls and buildings more effectively than VHF signals, making them more suitable for indoor and urban environments.
• Frequency Congestion: UHF frequencies tend to be more congested than VHF frequencies, as they are used by a wider range of communication systems and devices.

In summary, the main differences between VHF and UHF lie in their frequency ranges, propagation characteristics, and applications. VHF signals typically travel farther and are less affected by obstacles, while UHF signals have better penetration in urban environments and are more susceptible to multipath propagation. In amateur radio, both VHF and UHF bands are used for various communication purposes, including local and regional communication, repeaters, and digital modes.