Simple...
Either rent a larger size hammer drill with a 1/2' bit and 1 - 1 1/2" spade bit and cheese hole a circle with the bit and then punch it out with the spade bit. Cost about $50 - $60
Or, buy a hammer drill from Northern tool, cost about $100 add in a couple of drill bits at $15 - $40.
I use to borrow, once rented, now own the Northern tool unit, works fine for the occasional use, last week I just used it to blast a 1" hole, 18" deep through my "thin side" stone and concrete foundation. Worked like a charm. Going through a concrete foundation is a piece of cake, hammer drill goes right through, you might hit some rebar, generally the bit will just work around it.... Now when I hit a piece of granite in my foundation, it can take 5minutes to drill a half inch.....I have found that tougher than rebar.
Spend the money, and buy the Northern, you'll probably need to drill another hole for something.