On June 23, 2017, WNJU Telemundo 47 officially began broadcasting from One World Trade Center (1WTC) in New York, becoming the first station to return to this site since Sept. 11, 2001. Other New York City stations will be joining WNJU there soon—WCBS, WNBC, WPXN and WNET—sharing the UHF and VHF panel antennas mounted on the spire.
The UHF panel antennas, RFS models PEP40 and PEP96, contain two crossed dipoles (in an “X” configuration) with the +45-degree and –45-degree elements fed with two transmission lines. Transmitter power is split evenly between the +45 and –45-degree elements. The phase of the two feeds is varied to change the polarization from horizontal polarization only to full circular polarization. Transmitting only vertical polarization would be possible if the FCC allowed it. polarization from horizontal polarization only to full circular polarization. Transmitting only vertical polarization would be possible if the FCC allowed it.
|John Gonzalez (L), WNJU director of technology and operations, and John Lyons, assistant vice president and director of broadcast communication of the Durst Organization, push the button to fire up the WTC1 broadcast antenna.|
TESTING FIRST FULL-POWER SIGNALS
Prior to the official launch of WNJU’s signal from 1WTC we conducted test transmissions. In my RF Technology column “An Inexpensive Setup for Rapid DTV Field Measurements” (Jan. 11, 2015), I described the system used for testing coverage from test transmitters and antennas installed at 1WTC. These tests were done using circular polarization and showed the site was capable of penetrating the “midtown mountain” of high-rises to provide coverage on the north side of Manhattan.
When the WNJU transmitter installation at 1WTC was completed enough to allow overnight on-air testing at full power, we conducted measurements as close as possible to a circle with an 8-mile radius centered on 1WTC. Unlike the 2015 measurements, this…