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MIXTV Installs Elliptically Polarized Dielectric TUM Antenna

Dielectric Communications announced that Brazilian television broadcaster MIXTV has purchased and installed a TUM elliptically polarized antenna. The TUM antenna is a broadband panel antenna that provides true elliptical polarization and allows different ratios of horizontal to vertical effective radiated power. The TUM series antennas was introduced at NAB this year.

Sergio Guaglianoni, technical director for MIXTV, explains. "Having successfully broadcast with a Dielectric antenna system since 1990, MIXTV has now selected Dielectric to upgrade our facility with a new TUM panel antenna system for DTV," he said. "This UHF broadband elliptically polarized antenna, combined with the output of three NEC transmitters, will allow us to maintain our broadcast transmissions in all directions with the same high-performance coverage we've enjoyed for the past 20 years of operation."

The antenna, which was purchased at NAB, transmits the combined output of three transmitters: an analog transmitter at 60 kW for Channel 14, a DTV transmitter at 20 kW for Channel 15, and an analog transmitter at 60 kW for Channel 16.

The TUM antenna is a high-power broadband antenna with a variable polarization ratio for maximum flexibility—from elliptical polarization to full circular polarization. This flexible design allows for a wide range of omni or directional pattern options, as well as unique elevation pattern requirements such as beam tilt and null fill. The polarization ratio is controlled by varying the phase relationship, a technique that eliminates the need for unequal power dividers and maximizes the overall power rating of the panel by always applying uniform power to the radiating elements. The antenna features a single-input design that reduces feed system complexity by eliminating unnecessary connections and thus increases system reliability. The TUM antenna provides 200-MHz bandwidth, with a VSWR less than 1.1:1, and a power rating of 2 kW per panel.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.