It's been one of the better-kept secrets of the digital age that only broadcast engineers, technology execs, and perhaps a handful of other early adopters seemed to appreciate: Some of the best-looking HD content available anywhere is purely terrestrial--and, of course, it's free.

While the once-ubiquitous outdoor TV antenna and indoor rabbit ears may seem relics of the distant past to some observers, the costs of subscribing to HD via cable or DBS (not to mention the hard, cold fact of digital compression) have reportedly led to a renewed interest in antennas. When one company advertised that it was giving away free antennas shortly before this month's Super Bowl, the lines were around the block, Newsweek reports in its Feb. 19 edition.

Some antenna firms, including Terrestrial Digital of St. Louis and Audiovox of Hauppauge, N.Y., said the demand for their products is sky-high right now from HD set owners. Terrestrial Digital's sales have doubled annually since 2003, says its founder, who started up by selling antennas out of the back of his truck. "People thought I was selling drugs," he said.

About 85 percent of U.S. homes subscribe to cable or satellite and have not been dependent on antennas for many years. Therefore, antenna proponents say, educating consumers to the terrestrial facts of life in a digital world is still necessary because many people are not aware that HD broadcast content is easily retrievable OTA--provided, of course, you're within satisfactory geographic range of the signals.