Too late folks. We've been advertising our presence to the entire Cosmos for about a century now. The first radio transmissions by Marconi, et al, didn't just travel around Planet Earth - but also out into space. They've been propagating outward (imagine an expanding sphere that - by now - contains quite a few stars: some of which will have planetary systems) at the speed of light (186,000 miles per second) and will continue to do so for eternity.
As for ET coming here to nick our resources; I wouldn't worry about it, he probably mastered the trick of transmutating one element into another a long time ago. Once we have mastered 'cold fusion' we will have done the same.
Then there is the 'lebensraum' argument, I wouldn't worry about that either, with his technology ET can probably pitch his tent anywhere in the Cosmos he cares to.
I'm not quite sure why a luminary like professor Steven Hawking should wade into the argument. Perhaps it has something to do with with his recent tv documentory and the fact that he knows that ET knows more than he does. He 's maybe anticipating bad peer reviews.