A method includes forming a transistor over a substrate; forming a conductive structure over the substrate, such that a first end of the conductive structure is electrically coupled to a gate of the transistor, and a second end of the conductive structure is electrically coupled to the substrate; applying biases to the gate of the transistor and source/drain structures of the transistor; determining whether the first end and the second end of the conductive structure are electrically connected; generating, based on the determination, a first result indicating that the first end and the second end of the conductive structure are electrically connected; and qualifying the conductive structure as an antenna in response to the first result.