Blaw-Knox tower

Blaw-Knox tower
IndustryManufacturing
Headquarters
United States
ProductsSteel

The Blaw-Knox company was an American manufacturer of steel structures and construction equipment based in Pittsburgh, Pennsylvania. The company is today best known for its radio towers, most of which were constructed during the 1930s in the United States. Although Blaw-Knox built many kinds of towers, the term Blaw-Knox tower (or radiator) usually refers to the company's unusual "diamond cantilever" design, which is stabilized by guy wires attached only at the vertical center of the mast, where its cross-section is widest.[1] During the 1930s AM radio broadcasting stations adopted single mast radiator antennas, and the Blaw-Knox design was the first type used. A 1942 advertisement claims that 70% of all radio towers in the United States at the time were built by Blaw-Knox.[2]

The distinctive diamond-shaped towers became an icon of early radio. Several are listed on the United States National Register of Historic Places,[3][4] the distinctive diamond antenna design has been incorporated into logos of various organizations related to radio and a very large (scale) replica of the WSM (AM) Blaw-Knox tower has been built into the Country Music Hall of Fame and Museum.

  1. ^ "Half Wave Mast Antenna: A 665 foot structure which constitutes a new departure" (PDF). Radio-Craft. 3 (5). Mount Morris, Illinois: Techni-Craft Publishing Corp.: 269 November 1931. Retrieved August 31, 2014.
  2. ^ Blaw-Knox Division of Blaw-Knox Company. "On duty for the duration (advertisement)". Broadcasting and Broadcast Advertising. 22 (19). Washington, D.C.: Broadcasting Publications, Inc.: 104.
  3. ^ WSM tower gets 'historic' status, The Tennessean, April 14, 2011
  4. ^ "Weekly list of actions taken on properties: 3/14/11 through 3/18/11". National Park Service. March 25, 2011. Retrieved March 26, 2011.