In the 1950s and 60s, AT&T built thousands of microwave relay towers across the United States to create a transcontinental telecommunications system it called the Long Lines network. Decades have passed since they were last used for their original purpose, but the structures still dominate their surroundings. One dominates the countryside just south of Greenfield, Indiana.
Up until the 1940s, it was standard practice for phone companies to connect distant cities by cable. It was expensive, so AT&T designed an experimental microwave network called TDX in 1947. An improved technology called TD-2 was rolled out in 1950.
TDX and TD-2 systems relayed signals from distant origins through line-of-sight towers with unique horn-reflector antennas. Greenfield’s Long Line tower was built in 19551. Standing 258 feet tall2, the tower connected AT&T’s central office in Indianapolis twenty miles east to another tower twenty-nine miles southwest near Glenwood3.
Unfortunately, the network was obsolete by the 1980s when geostationary satellites, improved fiber optics, and digital networks became widespread. AT&T was broken up in 1984, and a successor company sold the Greenfield tower in 20004.
The structure retains its fan-shaped KS-15676 horn antennae and a pair of impressive SHX10As, but today, it’s used as part of American Messaging Services’ paging network5.
Sources Cited
1 Hancock County Office of Information & GIS Services. (2023). Parcel ID: 30-11-17-300-014.000-002. Hancock County, Indiana Assessor. map, Greenfield, IN.
2 FCC Registered Cell Phone and Antenna Towers in Hancock County, Indiana (n.d.). City-Data.com. Web. Retrieved November 14, 2023.
3 Long Lines Map and Information (n.d.). Web. Map. Retrieved November 12, 2023.
4 (See footnote 1).
5 Transmitter Characteristics (n.d.). Antennasearch. Web. Retrieved November 14, 2023.
