Abstract: An electronic identification system for identifying an animal moving through a portal structure is disclosed. A transponder worn on a rope or chain around the neck of the animal is energized by a multi-directional electromagnetic field generated by a double antenna loop in the portal structure. The transponder, when energized, will transmit identifying data back to the antenna loop after the electromagnetic field has been removed. That information will be processed by a microprocessor so that the animal can be identified. The antenna loop is secured within a flexible free-hanging curtain. The curtain is attached only at the top to the frame of the portal structure; the bottom of the curtain is free-hanging so that the curtain and antenna loop will not be damaged if the animal kicks the curtain. The system also includes two ultra-sonic transducers positioned at the entrance and exit of the portal.