Apex was an experimental radio broadcasting system introduced in the United States in 1934 that used high frequencies between roughly 25 and 42 MHz to achieve high fidelity sound with less static and distortion on AM stations. They were called "apex", "skyscraper" or "pinnacle" stations because of the height of the broadcast antennas used. Sine waves of various frequencies; the lower waves have higher frequencies than those above. ... A megahertz (MHz) is one million (106) hertz, a measure of frequency. ... Amplitude modulation (AM) is a form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal. ... A Yagi-Uda antenna An antenna or aerial is an electronic component designed to transmit or receive radio signals (and other electromagnetic waves). ...

The Federal Communications Commission thought initially that very high frequency (VHF) radio waves would have a small, discrete range, and would allow stations to broadcast in duplicate frequencies without interfering with each other. But as wattage increased, the opposite was realized: because of the short wavelengths associated with high frequencies, apex station signals could sometimes be heard on the other side of the planet at night. In October 1937, the FCC made public its allocation plan for VHF radio broadcasting: 75 channels with 40 kHz separation on 41.02 to 43.98 MHz for apex stations and 16 channels in 30-40 MHz for relay stations. Twenty-five of the 75 channels were reallocated for educational use in 1938. By 1939, apex stations were operating in 34 cities in 22 states. The FCCs official seal. ... Very high frequency (VHF) is the radio frequency range from 30 MHz (wavelength 10 m) to 300 MHz (wavelength 1 m). ... Wattage may mean: electrical power, measured in watts This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same title. ... A Grundig shortwave receiver Shortwave radio operates between the frequencies of 3,000 kHz and 30 MHz (30,000 kHz) and came to be referred to as such in the early days of radio because the wavelengths associated with this frequency range were shorter than those commonly in use at...

Until the late 1930s, commercially-made radio receivers did not operate within that band of frequencies, so early listeners of apex stations used self-built receivers, or built converters for existing models.

Most apex stations operated under experimental licenses, and were affiliated with and subsidized by commercially licensed stations. Apex radio broadcasting's goal of high fidelity sound was later realized by frequency modulation (FM), which operated at 43-50 MHz (Later 87.6-107.9 MHz), immediately above the apex band of frequencies. The FCC in 1939 began encouraging apex stations broadcasting in AM to consider the change to the technically superior FM system. Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ...

External links

• Apex broadcast stations in the U.S. in 1939
• Apex broadcast stations in the U.S. in 1942
• Apex broadcasting in Milwaukee
• Apex broadcasting in Detroit
• Apex and FM chronology