Band IV

Lore & Background

Sources differ on the exact frequency range of Band IV. The Swiss Federal Office of Communications, the Broadcast engineer's reference book, and Ericsson India Ltd define the range from 470 to 582 MHz. An EICTA paper defines it as 474 to 602 MHz, while the BBC defines it as 470 to 614 MHz. In Australia, UHF channel allocations are 7 MHz wide, and Band IV includes channels 28 to 35, with base frequencies from 529.5 MHz to 578.5 MHz. In New Zealand, UHF channel allocations are 8 MHz wide, and Band IV includes channels 25 to 35, with base frequencies from 506.0 MHz to 586.0 MHz.

In the United Kingdom, Band IV allocations are 8 MHz wide, traditionally consisting of 14 channels from UHF 21 to 34 inclusive. However, in the mid-1990s, the squeezing of analogue Channel 5 broadcasts into the existing national terrestrial TV transmitter network effectively closed a gap between bands IV and V, which was previously reserved for radar applications and home consumer devices. This stretched the practical definition of Band IV in the UK to cover 18 channels from UHF 21 to 38 inclusive. Aerials of the group A type cover this band.

Reader's Guide

Band IV's significance lies in its widespread use for television broadcasting across multiple countries and standards, including analogue, DVB-T, ATSC, and ISDB. It also supports mobile broadcast services such as DVB-H. The band's exact frequency boundaries vary by source and national allocation, reflecting differing regulatory and technical traditions. In the UK, the practical expansion of Band IV in the mid-1990s to accommodate Channel 5 broadcasts illustrates how operational needs can reshape band definitions, closing a gap previously reserved for radar and consumer devices. This flexibility has allowed Band IV to remain a core part of terrestrial television infrastructure, with dedicated aerial types (group A) designed to cover its range. Its legacy is tied to the transition from analogue to digital broadcasting and the ongoing use of UHF spectrum for both fixed and mobile television services.

Did You Know?

• Band IV is part of the ultra high frequency (UHF) spectrum.
• Sources disagree on its exact frequency range, with definitions spanning from 470–582 MHz to 470–614 MHz.
• In the UK, the band was traditionally 14 channels (UHF 21–34) but expanded to 18 channels (UHF 21–38) in the mid-1990s.
• Band IV is used for DVB-T, ATSC, ISDB, and DVB-H services.

Scope and Significance

The radio spectrum encompasses electromagnetic waves spanning from 3 hertz up to 3,000 gigahertz, or 3 terahertz. This range sits at the lowest-frequency end of the broader electromagnetic spectrum and has become the backbone of modern telecommunications. Radio waves within this band are the medium through which wireless communication, broadcasting, navigation, and countless other technologies operate. Because the spectrum is a finite, fixed resource, its efficient use has become a central concern in both engineering and public policy. The generation and transmission of radio waves are not left to chance; they are governed by strict national legislation and coordinated internationally through the International Telecommunication Union. This regulatory framework exists to prevent the inevitable interference that would arise if multiple users occupied the same frequencies without coordination. As demand from an ever-growing number of users continues to outpace the available bandwidth, the management of the radio spectrum has become one of the most consequential technical and political challenges of the modern era.

Regulation and Allocation

The International Telecommunication Union serves as the global coordinator for how the radio spectrum is divided and used. Under its Radio Regulations, roughly forty distinct radiocommunication services are defined, each assigned to specific frequency ranges. In many countries, portions of this spectrum are not merely allocated but actively sold or licensed to private operators—cellular carriers, broadcast television stations, and other commercial entities. These licensed ranges are commonly referred to by their intended purpose, such as cellular spectrum or television spectrum. The practical reality is that the spectrum is a fixed resource with no possibility of expanding its total bandwidth, yet the number of users demanding access has grown dramatically over recent decades. This growing congestion has become a powerful driver of innovation in telecommunications engineering. Technologies such as trunked radio systems, spread spectrum techniques, ultra-wideband transmission, frequency reuse, dynamic spectrum management, frequency pooling, and cognitive radio have all emerged as responses to the fundamental constraint that the available spectrum cannot be increased, only used more intelligently.

Physical Boundaries

The usable range of the radio spectrum is bounded by hard physical constraints at both extremes. At the low-frequency end, antenna size grows in direct proportion to wavelength, so as frequency drops, the structure needed to radiate power efficiently becomes impractically large. Below roughly 10 kilohertz, where wavelengths reach 30 kilometers, elevated wire antennas spanning kilometers are required, and very few systems operate there. Below about 30 kilohertz, audio modulation becomes impractical, limiting communication to slow data rates. The absolute lowest frequencies ever used for radio communication sit near 80 hertz, in extremely low frequency submarine systems built by a handful of naval powers. These employ ground dipole antennas 20 to 60 kilometers long, driven by megawatt-scale transmitters, and transmit only about one bit per minute. At the high-frequency end, atmospheric absorption is the limiting factor. Above 30 gigahertz, atmospheric gases absorb radio energy increasingly, reducing useful communication range to about one kilometer. In the terahertz band above 300 gigahertz, absorption by ozone, water vapor, and carbon dioxide renders the atmosphere essentially opaque, attenuating signals to zero within a few meters.

Band Structure and Planning

To manage the vast range of the radio spectrum in a practical way, the ITU divides it into twelve distinct bands, each beginning at a wavelength that is a power of ten in meters. Within each band, a formal band plan dictates precisely how the spectrum is to be used and shared. These plans specify the frequency range included, how individual channels are defined, and what content will be carried on them. Typical parameters set in a frequency plan include the channel numbering scheme, the spacing between carrier frequencies, the bandwidth or deviation allocated to each channel, the spectral mask governing how extraneous signals must be attenuated, the permissible modulation types, the kinds of information allowed such as audio, video, analog, or digital, and the licensing procedure for obtaining broadcast authorization. The actual authorized bands are defined jointly by the ITU and local regulatory agencies such as the United States Federal Communications Commission, while voluntary best practices among operators help further reduce the risk of interference. This layered system of international standards, national regulation, and industry self-discipline allows hundreds of different services to coexist within the same finite electromagnetic space.

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