KNHC uses a directional antenna due to an adjacent station in Olympia. I actually helped put that antenna up..twice. The first time, the manufacturer provided a mount thta wasn't designed correctly and wouldn't provide the antenna pattern as filed-for.
The other stations which use the Entercom tower on Cougar use a directional panel antenna to replicate the coverage of W. Tiger Mt., and to maximize signal over the market. I've never heard concerns of multipath from the Cascade Mountain Range. I doubt that would be a problem, given the mountains are much further away from the market than Cougar where the transmitters are.
