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Shortwave broadcasting in the United States allows private ownership of commercial and non-commercial shortwave stations that are not relays of existing AM/MW or FM radio stations, as are common in Africa, Europe, Asia, Oceania except Australia and Latin America. In addition to private broadcasters, the United States also has government ...
Broadband shortwave base antennas traditionally fall into two main categories: Resistively loaded antennas which can be inexpensive and reasonably compact but inefficient at lower frequencies. Large elaborate and very expensive, non-loaded designs. (These can cost upward of $80,000 to purchase and install).
The ALLISS module is a fully rotatable antenna system for high power (typically 500 kW only) shortwave radio broadcasting—it essentially is a self contained shortwave relay station. Most of the world's shortwave relay stations do not use this technology, due to its cost (15m EUR per ALLISS module: Transmitter + Antenna + Automation equipment).
ALLISS allows a broadcaster to change the following shortwave transmission parameters at any time: direction (azimuths from 0 to 360 degrees, rate: ~1 deg / 6 sec), broadcast frequency, and antenna configuration (i.e.: HR 4/4/1 -> HR 6/4/1). All of these transmission mode changes can take effect in as little as 5 minutes.
In telecom circles, any area with more than three antennas could be referred to as an antenna farm. In the case of an AM broadcasting station (mediumwave and longwave, occasionally shortwave), the multiple mast radiators may all be part of an antenna system for a single station, while for VHF and UHF the site may be under joint management.
Shortwave: Shortwave broadcasting in the United States also dates back to the 1920s, though the shortwave bands were nationalized during World War II and were not opened to private broadcasters again until 1962. Like AM, shortwave stations benefit from atmospheric propagation and can cover vast areas of territory, but the higher frequencies are ...
Before the HRS antenna became the default design for high power broadcasting in the 1950s, Sterba curtains were used to transmit shortwave broadcasts. Sterba curtains are modest-gain single-band curtain array antennas. They are named after Ernest J. Sterba, who developed a simple shortwave curtain array for Bell Labs in the 1930s. [1]