pitkäaaltisen

Pitkäaaltinen is Finnish for long-wavelength and is used as an adjective to describe electromagnetic waves with relatively long wavelengths compared to other parts of the spectrum. The term is used across physics, engineering, and education to denote waves whose wavelengths are substantially longer than those of visible light.

In radio technology, pitkäaaltinen typically refers to the longwave region, approximately 30 kilohertz to 300 kilohertz, corresponding to wavelengths from about 10 kilometers down to 1 kilometer. Longwave signals propagate mainly by groundwave during the day and through skywave reflection at night, which affects coverage and reception.

In other contexts, pitkäaaltinen describes radiation with long wavelengths, such as infrared or microwave bands. As wavelength increases, photon energy decreases, and interactions with matter change, influencing absorption, scattering, and detector design.

Practically, the long wavelength often demands large antennas for efficient transmission or reception and can yield strong diffraction around obstacles. Detectors and instruments aiming at long-wavelength radiation use specialized sensors tuned to the relevant spectral range.

The term is standard in Finnish technical literature and education as a descriptor, rather than a separate physical category. It can pair with nouns like säteily, radio, or infrapuna to specify the kind of long-wavelength radiation being discussed.