His final project as a student was to design an RF transceiver. He decided to work with the Microchip MRF49XA, which runs around $3 but will cost you $20 if you want it in a ready-to-use module.

These features and antennas fit into this ultra-miniature RF module, a tiny package measuring 9 x 9 x 1 mm, the smallest on the market. With extended temperature capability up to 105 o C, this device ...