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Electronic and mechanical pointing, signal processing, and clever element configuration come together in automotive hybrid sat-TV antenna design: Part 1
In bringing DIRECTV satellite signals into a car, design engineers had to ensure reliable, continuous service, all in a compact, aerodynamic package
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Passenger video entertainment is one of the hottest automotive electronics accessories available, with more than 50% of 2006 model year full-size SUVs shipping with some form of in-car video system. According to analyst firm Frost & Sullivan, more than 20 million cars will have video systems by 2011.
With a growing number of video passenger entertainment systems being sold both in the aftermarket and as a factory-installed component, the question then becomes "What will people watch on all these video screens?" Just like at home, where people watch more live TV than pre-recorded content, that same trend occurs anywhere TV screens appear, including cars. In addition, pre-recorded media like DVDs provide only short-term entertainment value and must be stored in the car. Clearly, the time has come for expanded content and live programming. In fact, Frost & Sullivan projects that more than three million automobiles in the U.S. will be equipped with live mobile satellite systems by 2011.
In 2003 KVH Industries introduced the TracVision A5, which allowed passengers to watch DIRECTV satellite television programs and enjoy XM Satellite Radio in their vehicles while on back roads or rolling down the highway.
In August 2006, KVH advanced the technology again with the introduction of the TracVision A7 (see above), a system that builds on the original technology of the A5 and significantly advances the state-of-the-art in mobile satellite TV. The A7 offers faster acquisition, increased versatility, greater reliability, and quieter operation, due to patented advances in satellite TV technology developed by KVH engineers.
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Several key innovations have made the TracVision A7 possible:
Hybrid antenna
At the heart of the TracVision A7 is the hybrid phased-array antenna. Until the introduction of the A5 and now the A7, the longstanding form of a satellite antenna was the familiar round or elliptical parabolic dish. However, these dish-style antennas have obvious drawbacks when used on the roof of an SUV or automobile. A dish antenna's overall size, height, and aerodynamic drag—even when covered by a dome—make the dish-approach unusable as a mobile satellite TV antenna.
Three aspects of mobile satellite TV antennas: The round parabolic TracVision M3 for boats, the elliptical parabolic R6 for recreation vehicles (RVs,) and the flat, hybrid phased-array A7 for cars and SUVs.
To fit the low profile and small size requirements of a car or SUV mobile TV unit, a new design was needed. In response to these daunting constraints—for example, the antenna package could not exceed a 5.3 inches in height—KVH engineers took a hybrid approach. They combined the best capabilities of electronic phased-arrays and mechanically pointed antenna systems to produce the TracVision A7 antenna hybrid. The resulting antenna has impressive operational features and excellent signal capture capability engineered into a thin package.
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