Latin America. Dielectric's low-power TV and FM business continues to grow as the company develops and expands its antenna and RF product portfolio of lower-power transmission systems. Radio stations in Florida and Puerto Rico represent two recent examples of how Dielectric has improved signal coverage for FM translators in challenging coverage areas.
Hal Kneller, a broadcast industry veteran who now works as an independent consultant, specified Dielectric's DCR-T antennas for FM translators associated with WSRQ-AM (Florida) and WMDD-AM (Puerto Rico). The DCR-T incorporates the benefits of Dielectric's FM ring-style antennas, giving low-power FM stations a cost-effective alternative to single-station systems. This makes the circular-polarized, branch-powered DCR-T an attractive option for broadcasters who need to improve signal coverage with modest technical budgets.
WSRQ's translator for 106.9 FM (W295BH) is part of a combined SFN and simulcast network that synchronizes programming across four stations in the Sarasota/Bradenton market. In an effort to improve coverage, the 250-watt translator, formerly located in Bradenton, moved to Sarasota following FCC approval. While the move would establish a stronger signal with better penetration into the building, the existing "economic antenna" had suffered recent water damage and would not adapt to the new directional signal pattern.
Kneller kept the station up in the air with a backup system while installing the bay-stemmed DCR-T antenna in his new tower, which he described as "very busy and charged." The compact DCR-T design was mounted on top of the 475-foot tower, using a tower tube initially intended for cellular antennas. The top mounting position, combined with the directional pattern designed for the translator, has substantially improved the effectiveness of the translator in the all-important Sarasota area.
Kneller also purchased two FM filters from Dielectric for the Sarasota site transmitter building, one powering 106.9 and the other powering a system on 99.1 FM. The two antennas are installed in the same tower at the same height. That raised significant interference concerns for both Kneller and the FCC, resulting in extensive intermodulation studies.
"Concerns about intermodulation were legitimate and challenged us to choose carefully when it came to a filtering solution," Kneller said. "While it made sense to opt for Dielectric given our choice of antenna, we still plan to conduct extensive testing using parking simulations and connecting the filters inside the building. We were relieved to know that there was no interference or interaction between the two signals. Like the DCR-T, dielectric FM filters are compact and easy to wall mount inside an RF building with limited space."
The WMDD system in Puerto Rico is also a "cross-service translator" that simultaneously broadcasts the main AM signal at 106.5. Licensed from the city of Fajardo, the translator is located 30 miles outside of San Juan at the eastern end of the island. The translator is located in the 400-foot tower of the AM station and provides better FM service to the local population.
"Puerto Rico is very mountainous and has challenging terrain for FM coverage in the area surrounding Fajardo," Kneller said. "We specified a two-bay omnidirectional DCR-T antenna with half-wavelength spacing, which directed the signal up and away from the ground. This is a common practice for translators and avoids interference with the outline of another radio station on the ground. Dielectric's design solved these concerns early on, and they packaged and shipped the antenna in a way that helped us quickly put all the elements together. It took less than two days to install the antenna and the new isocoupler, hang the two bays and run the new 7/8-inch transmission line down the tower."
Kneller adds that the robust quality of Dielectric's products provide greater resilience against the frequent tropical storms these two sites experience.
