The New 4m Band

 

The 4m band, also known as the 70 MHz band, is a band of frequencies in the Very High Frequency (VHF) range that is allocated for use by amateur radio operators. The exact frequencies and operating rules for the 4m band vary by country, but in general, the band is used for voice and digital communications over relatively short distances. The band is considered a "VHF-UHF transition" band, which means it is between VHF and UHF bands. Because of its unique characteristics, it offers great propagation characteristics and is especially useful for weak signal communications and for EME (Earth-Moon-Earth) communications.

Propagation on the 4m band can be affected by a variety of factors, including the time of day, the season, and the weather. During the daytime, propagation on the 4m band is typically limited to line-of-sight communications, with signals being reflected by the ionosphere. This means that communications are generally limited to distances of 100-150 miles, depending on the height of the antennas and the terrain.

At night, propagation on the 4m band can be greatly enhanced by the ionosphere, allowing for communications over much greater distances. Signals can be reflected back to the earth by the ionosphere, allowing for communications over thousands of miles. This type of propagation is known as "skywave" propagation.

The season also affects the propagation of the 4m band. During the summer months, the ionosphere is more active, which can lead to better propagation conditions.

Finally, weather can also have an impact on propagation. During periods of high solar activity, the ionosphere is more active, which can lead to improved propagation. On the other hand, during periods of low solar activity, the ionosphere is less active, which can lead to poor propagation.

So, the propagation on the 4m band is affected by different factors, it varies depending on the time of the day, the season, the weather, and the solar activity.