1.2.2 Spectrum as a Technical Resource

Electromagnetic radiation is the propagation of energy that travels through space in the form of waves. It includes the visible spectrum (light), as well as infrared, ultraviolet and x-rays. The radio frequency spectrum is the portion of electromagnetic spectrum that carries radio waves. The boundaries of radio spectrum are defined by the frequencies of the transmitted signals, and are usually considered to range from 9 kilohertz (kHz - thousand cycles per second) up to 300 gigahertz (GHz - billion cycles per second). However, technical change is making use of even high frequencies viable. Table 2.0 depicts the some of the many uses of radio spectrum associated with various bands derived from their inherent propagation characteristics.

Table 2 Radio Frequency Propagation

The key characteristics of spectrum are the propagation features and the amount of information which signals can carry. In general, signals sent using the higher frequencies have lower propagation distances but a higher data-carrying capacity. These physical characteristics of the spectrum limit the currently identified range of applications for which any particular band is suitable. Some spectrum (such as in the UHF band 300-3000 MHz) is known to be suitable for a wide variety of services and is thus in great demand.

Presentations delivered at the 2008 ITU World Radiocommunication Seminar, 8-12 December 2008, available at: www.itu.int/ITU-R/index.asp?category=conferences&rlink=seminar-program&seminar=geneva-2008&lang=en