The projector itself wont know what to do with the raw antenna signal. You have to have something in the middle decoding the signal and allowing you to change channels etc. Been a while since I've even used one but a real simple low tech solution might be to use a VCR. PLug the coax cable coming off the antenna into the "Cable In" on the back of the VCR and run the yellow RCA plug from one of the "Video Out" red, white, and yellow plugs to the yellow "Video In" on the projector. Then send the red and white RCA from the same "out " on the VCR to your receiver for audio.
Option 2 would be run all three red, white, yellow to the reciever. And then the single yellow RCA from the reciever to the projector.
The S-Video can be used in-place of the yellow RCA with debatable gains in quality. Still gotta use the red & white audio though.