The short, simple answer is because the station is low-power, explained WILM-TV General Manager Constance Knox.
“When we did the digital transition our over-the-air footprint was about the size of a golf ball,” she said. “Now we’re at the size of a dinner plate. When there’s a lot of rain, the outer fringes, like Bald Head Island, may have issues. It’s kind of like DirecTV, you either have a great signal or you don’t.”
Speaking on behalf of WILM-TV, Knox said that station’s signal increased when it switched to digital.
More information about the transition to digital TV
Date posted: October 4, 2010
User-contributed question by:
Anonymous

WILM is a great station. I get their signal very well in the area between Surf City and Holly Ridge, both day and night.
I am from the Raleigh area and loved WRAL for both the news and weather and this station helps me watch something I love from back home. At night I can get WRAL on my tv very clear.
The digital transition on OTA TV was a good thing for some stations and a bad thing for others. SInce some of the stations went to UHF channels, they could run antennas with more gain, and therefore “increaee their power” without having to get bigger transmitters.
WILM’s digital signal does very well in this area for a lower power signal than the other stations in the area. I know their transmitter and antenna used to be of Wrightsville Avenue behind Empie Park, but I don’t know if it has moved since then.
Keep it up WILM, and I would love to see you become a full power player sometime in the future.