## Introduction

A variety of radio antennas on Sandia Peak near Albuquerque, New Mexico, US. FM and television transmitting antennas are often located on high towers or mountain peaks, to maximize transmission range. Antennas of both kinds are shown here, along with round dishes and drums for point-to-point microwave communications (for example from studio to transmitter).

## Selected article

The electromagnetic spectrum is the range of all possible electromagnetic radiation. Also, the "electromagnetic spectrum" (usually just spectrum) of an object is the range of electromagnetic radiation that it emits, reflects, or transmits.

The electromagnetic spectrum, extends from the frequencies used in electric power grids (at the long-wavelength end) to gamma radiation (at the short-wavelength end), covering wavelengths from thousands of kilometres down to fractions of the size of an atom. It is commonly said that EM waves beyond these limits are uncommon, although this is not actually true. The 22-year sunspot cycle, for instance, produces radiation with a period of 22 years, or a frequency of 1.4*10−9 Hz. At the other extreme, photons of arbitrarily high frequency may be produced by colliding electrons with positrons at appropriate energy. 1024 Hz photons can be produced today with man-made accelerators. In our universe the short wavelength limit is likely to be the Planck length, and the long wavelength limit is the size of the universe itself (see physical cosmology), though in principle the spectrum is infinite.

## Selected station

BBC Local Radio is the BBC's regional radio service for England and the Channel Islands, consisting of 40 stations. Initially, stations had to be co-funded by the BBC and local authorities, which only some Labour-controlled areas proved willing to do. Radio Leicester was the first to launch on 8 November 1967, followed by Sheffield, Merseyside and Nottingham. By the early 1970s, the local authority funding requirement was dropped, and stations spread across the country; many city-based stations later expand their remit to cover an entire county. Today, stations are asked to target their coverage to Dave and Sue, two fictional fifty-five-year-olds.

## Subcategories

The following are categories relating to radio:

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## Selected biography

Fred Allen (born John Florence Sullivan on May 31, 1894 in Cambridge, Massachusetts, died March 17, 1956 in New York City) was an American comedian whose absurdist, pointed radio show (1934–1949) made him one of the most popular and forward-looking humorists in the so-called classic era of American radio.

His best-remembered gag may be his long-running mock feud with friend and fellow comedian Jack Benny. Allen has been considered one of the more accomplished, daring and relevant humorists of his time. A master ad libber, he constantly battled censorship and developed routines the style and substance of which influenced future comic talents. Perhaps more than any of his generation, Fred Allen wielded influence that outlived both his contemporaries and the medium that made him famous.

## WikiProjects

• Radio December 12, 2006 "...to create, expand, and maintain wikipedia articles related to radio, including radio propagation and reception, radio programming, radio personalities, and the business of radio." (Example: Mutual Broadcasting System)
• Amateur Radio August 24, 2006 "...to improve Wikipedia's articles related to Amateur radio, maintain the amateur radio category and its sub-categories for clean organization, and to produce and maintain templates for Amateur radio-related topic identification." (Example: Amateur radio)
• Radio Stations February 15, 2005 "...to coordinate the activities of creating and maintaining articles about radio stations." (Example: Pulse FM Kingborough & Huon)
• Podcasting January 21, 2007 "...to make Wikipedia's knowledge of notable Podcast and podcast-related information as complete as possible." (Example: Podcast)

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