New tunable waveguide and cross-coupling innovations reduce configuration times, improve power handling through the filtering process


RAYMOND, Maine – April 20, 2017Dielectric, a pioneer in purpose-engineered antennas and RF systems for TV and radio broadcasters, will show new innovations for RF filtering inside transmission facilities at the 2017 NAB Show, taking place April 24-27 at the Las Vegas Convention Center (Booth C2613).

For TV systems, Dielectric will unveil a 60 kW tunable waveguide filter design that delivers a boost in efficiency and voltage handling capability for the Spectrum Repack, and future ATSC 3.0 applications.

“Tunable filters have been around for some time, but there has been a goal in the broadcast community to increase their power handling capabilities,” said Derek Small, senior engineer, Dielectric. “In the past, liquid cooling has been used to improve filter power ratings. Dielectric’s tunable waveguide design is an industry first, in part because it generates a minimal amount of heat. We’re achieving higher air-cooled power levels than anything available today that is liquid-cooled.”

Small adds that using a high-power air-cooled filter has no bearing on the broadcaster’s choice of transmitter.  Since most high-power TV transmitters are liquid-cooled, Dielectric’s tunable waveguide air-cooled filter will reduce operational costs inside the plant.  “Using a liquid-cooled filter means pulling liquid from the transmitter,” he said. “That liquid is used to cool the transmitter, and in essence you rob the transmitter of an important cooling source. In some cases, a separate cooling system may be required, which presents an additional capital expense and maintenance.  Our system simplifies the cooling requirements and reduces the complexity of the installation.”

While the waveguide innovation is impressive, the “tunable” aspect remains significant – especially at a time when most broadcasters are concentrating on the Spectrum Repack. The tunable design simplifies the overall architecture, reducing size and accelerating installation. The “one-size-fits-all” design approach for any broadcaster on a UHF channel results in quicker manufacturing and delivery. Once installed, the design effortlessly adapts to environmental changes such as temperature and humidity, ensuring harsh conditions do not adversely affect channel tuning as signals move through the RF filtering process.

“Our customers retain the efficiency of traditional dual-mode cavities with our tunable waveguide design,” said Keith Pelletier, vice president and general manager, Dielectric. “The compact design is easy to install and returns real estate to the RF plant. These are very important benefits as our customers move to new channel assignments during the Repack, and looking forward, the higher voltage handling capability of waveguide is an ideal benefit for ATSC 3.0 systems.”

Cross-Coupling Innovations for Radio

For FM broadcasters, Dielectric continues to lower their initial and operational costs by reducing the amount of parts required to filter two or more channels. At the 2016 NAB Show, Dielectric introduced a new field-tunable, FM two-channel manifold combiner that eliminated coaxial Tee junctions, line and elbows, effectively reducing footprint and returning space to the broadcaster.

This year Dielectric has evolved this design by adding unique cross couplings to its manifold filter design, effectively allowing less frequency separation for combined channels.  Since fewer cavities are used, efficiency is improved and operational costs are reduced.

“Higher-order filters have been required for channel combiners and IM reduction due to the crowded FM spectrum, and have a tendency to reduce efficiency,” said Small.  “Higher order filters with large amplitude roll-off and delay can add asynchronous AM, and reduce stereo separation in the FM signal. From a classic design standpoint, the use of constant impedance FM combiners means twice as many filters and components and raise both initial and operational costs. Our new cross-coupled designs tackle these problems with much less complex architecture in shared FM facilities.”

About Dielectric

Based in Raymond, Maine, Dielectric LLC is a wholly owned subsidiary of Sinclair. Dielectric is a leading provider of innovative broadcast products. From remote stations to major markets, Dielectric has been delivering solutions for every need since 1942. Dielectric is an innovative, customer-centric organization with a long history of engineering excellence in designing and manufacturing high-quality broadcast solutions. The Company is a trusted partner of broadcasters worldwide. More information can be accessed at

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