Although there are real-world limitations, yes the F-15 radar has look-down capabilities meaning it can pick targets out of ground returns. I won't go into how it does this, but there are several good books on airborn radar principles available at amazon.com.
Mini D is absolutely correct on the pedigree of the F-111... It turned out to be a horrible carrier "fighter" and they never did give it more than a rudimentary A-A capability in the USAF (it could carry aim-9s and some models had a basic a-a radar mode) but yea it was an amazing strike aircraft. Fast, reliable (2 engines!), weapons system officer to focus on precision weapons and systems management, big bomb load, big fuel capacity. Pretty much everything the JSF isn't, but that's another story.
At least the JSF carries more gas than an F-16... whoops that's off topic too.
