Originally Posted by
Eggman
Ever pay attention to card access systems for buildings? Some you gotta swipe (like a credit card) others you just present the card near the card reader - those are called proximity cards.
The pair (card & reader) use induction, similar to a transformer with two windings - a primary & secondary. The card reader acts as the source of energy by inducing an electrical current into the antenna of the card. Once the card is presented within the proximity of the operating range of the reader it will wake up the tiny tiny little chip embedded between the layers of the card, and that little chip transmits it's signal to the reader. The reader may either decide itself whether to unlock the door, or send the code to a central database for the unlock decision.
It's just a guess, but I'm guessing you are looking at similar technology, Wallythacker. But I strongly doubt that your Mirage key does not have a transponder chip. Just can't tell from here... Here's a fun experiment that won't cost me a dime - have a new blank key cut and tell us it it'll start your Mirage haha.