I'm glad it's working out great for you. But, to be clear, there's nothing magic about a digital antenna vs the older analog ones. The station is still transmitting the signal on good old VHF/UHF frequencies.
Many stations moved their digital signals up to a UHF band during the transition -- when they were broadcasting both. And many of those moved back when the move to digital was complete.
My good old RadioShack Antenna from the 80's in my attic is pulling in the digital stations around here beautifully.
What some manufacturers do is see an antenna with better UHF reception capabilities as "digital".
But, what the hey, for under $20 if it works...
Great!