These low energy consumption FM antenna programs glow on the dial

Brian Galante
Especially for the weekly tech summary

dielectricThe low-power TV and FM business continues to grow as the company develops and expands its antenna and RF product portfolio of low-power broadcast systems.

Radio stations in Florida and Puerto Rico are two recent examples of how Dielectric has improved signal coverage for FM translators in challenging coverage areas.

Hal Kneller, a broadcast industry veteran who is now an independent consultant, specified DCR-T dielectric antennas for FM translators connected to WSRQ-AM in the Sarasota market and WMDD-AM on the far eastern coast of Puerto Rico .

The DCR-T offers the advantages of Dielectric’s FM ring antennas and offers FM transmitters with low power consumption an alternative for single station systems. This makes the branched, circularly polarized DCR-T a compelling option for broadcasters who need to improve signal coverage.

WSRQ’s 106.9 FM translator (W295BH, in Sarasota) is part of a mixed SFN and simulcasting network that synchronizes programming across four stations in the Sarasota-Bradenton radio market.

To improve coverage, the previously Bradenton-based 250 watt translator W295BH was relocated to Sarasota. While the move would produce a stronger signal with better penetration of the building in the center of Florida’s Suncoast region, the existing “budget antenna” had recently suffered water damage.

Thus it would not match the new directional pattern of the signal.

Kneller kept the station in the air with a backup system while the DCR-T antenna was installed with a shaft on the new tower, which he described as “very busy and loaded”. The compact DCR-T design was mounted on the 475 foot high tower with a tower tube originally intended for cellular antennas. The top-mounted position combined with the directional pattern developed for the translator has greatly improved the translator’s effectiveness in the vital area of ​​Sarasota.

Kneller also bought two dielectric FM filters for the transmitter building at the Sarasota site, one feeding 106.9 and the other feeding a 99.1 FM system. The two antennas are installed on the same tower at the same height. This created significant interference problems for both Kneller and the FCC, which led to extensive intermodulation studies.

“The concerns about intermodulation were justified and prompted us to choose carefully when choosing a filter solution,” said Kneller. “Although it made sense to opt for Dielectric given our antenna selection, we planned extensive tests with parking lot simulations and by connecting the filters in the building. We were relieved to learn that there was no interference or interaction between the two signals. Like the DCR-T, the FM dielectric filters are compact and easy to wall mount in an RF building with limited space. “


The WMDD system in Puerto Rico is also a “cross-service translator” that simulates the main AM signal at 106.5 MHz. The translator licensed for the city of Fajardo is located 30 miles outside of San Juan on the eastern edge of the island. The translator sits on top of the 400 foot tower of the AM station and provides better sounding FM service to the local population.

“Puerto Rico is very mountainous and has challenging terrain for FM coverage around Fajardo,” said Kneller. “We specified an omnidirectional DCR-T antenna with two bays and half wavelength spacing that directs the signal up and away from the ground. This is a common practice for translators and avoids disturbing the contour of the floor of another radio station. Dielectric’s design resolved these issues in advance and packaged and shipped the antenna so that we could bring all of the elements together quickly. It took less than two days to install the antenna and new isocoupler, hang up the two drawers, and run the new 7/8 ”transmission line down the tower. “

And while Kneller sees that many broadcasters are sticking to “budget antennas” for translators, he emphasizes dielectric for products with a professional stainless steel design. In his view, it offers long life for lower powered systems, as well as the benefits of low VSWR, zero fill, and all of the other high performance attributes you’d expect for full power FM transmitters.

Edited by Adam Jacobson of Sarasota County, Florida.

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