Band I

Lore & Background

In the UK, Band I was originally used by the BBC for monochrome 405-line television; the French former 455-line (1937–1939) then 441-line (1943–1956) transmitter on the Eiffel Tower in Paris, and some stations of the French monochrome 819-line system also used Band I. Both 405-line and 819-line systems were discontinued in the mid-1980s. Other European countries used Band I for 625-line analogue television, first in monochrome and later in colour. This was gradually phased out with the introduction of digital television in the DVB-T standard, which is not defined for VHF Band I, though some older receivers and some modulators do support it.

In European countries that used System B, the band was subdivided into three main channels (E2, E3, E4), each 7 MHz wide. Italy used slightly different allocations, such as channel IA and the out-of-band 'channel IC' (video: 82.25 MHz, audio: 87.75 MHz). Some countries such as Ireland, France, and the United Kingdom did not use System B and therefore used different frequencies. Russia, Ukraine, Kazakhstan, and a few other countries still broadcast analog TV on Band I in 2023.

In North America, the band is subdivided into five channels for television broadcasting, each occupying 6 MHz (System M). Channel 1 is not used for broadcasting. The upper end of this band, 87.5 to 88 MHz, is the lower end of the FM radio band. In the United States, the FCC occasionally issues a license for 87.9 MHz; 87.7 MHz, approximately the same frequency as the audio feed of channel A6, is used by some television licenses to broadcast primarily to radio.

Reader's Guide

Band I's significance lies in its foundational role in the development of television broadcasting across multiple continents. It was the first VHF band formally defined for television at the 1961 Stockholm Conference, and it accommodated a variety of analog television systems—405-line, 441-line, 819-line, 625-line, NTSC, and PAL—each with different channel spacings (6, 7, or 8 MHz). The band's legacy includes the gradual transition from analog to digital television, with most Band I transmitters switched off between 2006 and 2020 in Europe, and high-power analog stations in the United States ending on June 12, 2009. However, digital television in this band faces problems with impulse noise interference. The band also supports FM radio at its upper edge (87.5–88 MHz), and in Brazil, AM radio stations have migrated to an Extended FM band (76.1–87.5 MHz) using frequencies from former analog TV channels. Amateur radio operators use the adjacent 6-meter (50 MHz) and 4-meter (70 MHz) bands, where E-skip propagation events in summer allow reception of distant TV stations (TV DX) over 800–2,000 km. The band's continued use in some former OIRT countries for analog TV in 2023 underscores its enduring, though diminishing, presence.

Did You Know?

• Italy's channel IC (video: 82.25 MHz, audio: 87.75 MHz) was used by the first RAI transmitter in Turin, originally a US WWII NTSC transmitter.
• The upper end of Band I (87.5–88 MHz) is the lower end of the FM radio band.

Definition and Scope of the Radio Spectrum

The radio spectrum encompasses electromagnetic waves spanning from 3 hertz up to 3,000 gigahertz, or 3 terahertz. As the lowest-frequency category of electromagnetic radiation, its lower boundary is essentially arbitrary—there is no true minimum frequency below which a wave ceases to be a radio wave. At the upper end, the boundary with infrared is fluid and field-dependent. The terahertz range, from 300 gigahertz to 3 terahertz, occupies a gray zone: the ITU classifies it as radio, while spectroscopic researchers treat those same frequencies as far or mid-infrared. The ITU's formal definition describes radio waves as electromagnetic waves of frequencies arbitrarily lower than 3000 gigahertz that propagate through space without an artificial guide. This extraordinarily broad range underpins virtually every form of modern wireless communication, from deep-sea submarine signaling to the cellular networks that connect billions of devices.

Regulatory Architecture and Licensing

Because the radio spectrum is a finite, shared resource, its use is tightly governed at multiple levels. The International Telecommunication Union coordinates global allocation, defining roughly forty distinct radiocommunication services within its Radio Regulations. National bodies such as the United States Federal Communications Commission implement these rules locally, often selling or licensing specific frequency ranges to private operators including cellular carriers and broadcast television stations. For each allocated band, the ITU publishes a detailed band plan specifying channel numbering schemes, carrier spacing, bandwidth, spectral masks, permissible modulation types, content restrictions, and licensing procedures. This layered system of international coordination, national enforcement, and voluntary best practices exists to prevent interference among the many users who depend on the same fixed pool of frequencies, ensuring that transmitters and receivers remain compatible across borders.

Physical Boundaries and Practical Constraints

Despite its vast span, the radio spectrum is bounded by hard physical constraints at both extremes. At the low-frequency end, antenna size grows in proportion to wavelength; below roughly ten kilohertz, transmitting efficiently requires elevated wire antennas stretching kilometers in length. Below about thirty kilohertz, audio modulation becomes impractical, leaving only very slow data transmission. The extreme low end has been exploited by a handful of naval services for extremely low frequency submarine communication, using ground dipole antennas twenty to sixty kilometers long driven by megawatt transmitters, yet achieving only about one bit per minute. At the high-frequency end, atmospheric absorption becomes the limiting factor. Above thirty gigahertz, gases such as water vapor, ozone, and carbon dioxide increasingly attenuate signals. By thirty gigahertz, useful range drops to roughly one kilometer, and in the terahertz band above three hundred gigahertz, the atmosphere is effectively opaque, reducing signal strength to zero within mere meters.

Spectrum Congestion and the Drive for Efficiency

Because the radio spectrum is a fixed resource that cannot be expanded, growing demand has made it increasingly congested over recent decades. This scarcity is a primary driver behind a wave of modern telecommunications innovations designed to extract more utility from the same bandwidth. Techniques such as trunked radio systems, spread spectrum, ultra-wideband, frequency reuse, dynamic spectrum management, frequency pooling, and cognitive radio all aim to improve spectral efficiency without adding new frequencies. The ITU divides the spectrum into twelve bands, each beginning at a wavelength that is a power of ten in metres, and allocates non-overlapping ranges to similar services—broadcasting, mobile radio, navigation—to minimize interference. Ranges are commonly referred to by their provisioned use, such as cellular spectrum or television spectrum, reflecting the practical reality that every hertz is contested, carefully managed, and increasingly precious.

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