Which frequency band is used only for experimental purposes?

The Extremely High Frequency (EHF) band, which ranges from 30 GHz to 300 GHz, is specifically designated for experimental purposes in various applications such as research, scientific exploration, and technological testing. This band is part of the larger microwave spectrum, but it is particularly noted for its use in experimental settings where new communication technologies and radar systems are developed and tested.

The allocation of EHF for experimental use allows researchers and engineers to innovate without the constraints typically applied to more established frequency bands used for commercial or public communication. This freedom is vital for advancing technology and understanding the behavior of radio waves at these high frequencies.

In contrast, other bands like UHF, SHF, and microwave frequencies may encompass both experimental and established commercial communications, making them less exclusive for experimental use. Thus, the unique classification of the EHF band solidifies its role within the realm of experimentation and innovation.