Broadcasting and Wireless Communications
at the World Trade Center

Wireless communications sites are commonly collocated with broadcast facilities. Perhaps one of the more obvious examples of this practice is the World Trade Center (WTC) buildings in New York where a major broadcast installation operates from the north tower of the WTC along with approximately 85 telecommunications antennas. A major project was undertaken for Motorola to investigate the ambient RF field environment on the roof of the north WTC tower, taking into account the background fields produced by the many broadcasters at the site as well as the contributions from the numerous, roof-mounted communications antennas.

An intensive series of field measurements over a three day period was obtained of just the broadcast fields using five measurement teams, each equipped with identical broadband, isotropic, frequency shaped probes. Measures of spatially averaged RF fields were obtained at approximately 900 locations on the roof during different modes of broadcast operations, including a tower maintenance mode where certain TV stations operated from lower mounted auxiliary antennas.

A specially modified version of the RoofView™ software (developed by Richard Tell Associates, Inc., see RF Safety Products area of this web site) was employed to perform spatial interpolation of the many measurement values, to compute the expected RF field levels associated with the many wireless antennas and to graphically plot the resulting RF fields determined from the combination of both broadcasting and wireless communications activity. The spatial resolution of the RoofView™ program is one foot.