Originally developed by RCA, the pylon antenna design has become a vital building block for Dielectric to continue its innovation in TV antennas. However, the cylindrical design attributes of pylon antennas historically translated to narrow bandwidth characteristics making it impractical for FM signals. As Dielectric worked with the pylon antenna design for its digital television antennas, then subsequently for repack antennas in the VHF band, it learned a thing or two about expanding the bandwidth of a pylon antenna, according to Keith Pelletier, Vice President General Manager of Dielectric.
“We’ve learned a lot from working with the basic building block of the pylon antenna during the broadcast repack,” Pelletier said. “And, essentially, once we developed the broadband pylon antenna for VHF, a light bulb went off and we knew we could do something similar in the FM arena.”
Dielectric is now bringing the high-efficiency, low wind-load, and reliability of its broadband pylon TV antennas to FM broadcasters with its new FM pylon (FMP) antennas, which represent the broadcast industry’s first slot cavity microstrip FM antenna product family. The benefits to high-power FM broadcasters of the antenna include multicasting, pattern flexibility, increased reliability, and smaller tower footprint.
Over the past year, Dielectric developed an FMP antenna with broader bandwidth until it covered the whole FM band. “We can utilize the pylon antenna with the features that we designed in VHF and UHF bands and it translates to any frequency band, thus making the FMP design timeline very efficient. In addition, the full band operation and power handling capabilities will make multicasting off that antenna very easy to do,” Pelletier said.
The engineering breakthroughs that led to the FMP include reducing the antenna’s Q factor, which improves the bandwidth significantly, from one to 20 percent. That translates to full FM band operation.
“You want the lowest Q factor possible in that circuit to get the most bandwidth, which we were able to accomplish,” Pelletier explained. “The other thing you need to be careful with is phase cancellations within the antenna system if you want to get the maximum overall bandwidth. So there are multiple advanced engineering techniques that we utilized to make this product come to fruition.”
With roots dating back to 1942, Dielectric has strived to be a technology leader and innovator in radio and television transmission antennas for decades, Pelletier told Inside Towers. For example, it developed the first dual-polarized FM antenna in the 1960s, which introduced the concept of circular polarization from a single FM antenna element. In the late 1970s, the company introduced a quadrupole design with bandwidth improvements that remain in modern ring-style antennas.
Dielectric will publicly share full details of the FMP antenna family for the first time at the 2022 NAB Show, April 24-27, Las Vegas Convention Center. Stop by and see them at Booth W7017.
For more information, visit: dielectric.com.
By J. Sharpe Smith, Inside Towers Technology Editor
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