Patent 7324062 was granted and assigned to Mitsumi Electric on January, 2008 by the United States Patent and Trademark Office.
An antenna unit comprises a hollow cylindrical member obtained by forming a flexible insulating film member into a hollow cylinder and an antenna pattern composed of four conductors formed on an inner peripheral surface of the hollow cylindrical member. A phase shifter pattern is formed on the inner peripheral surface of the hollow cylindrical member so as to be electrically connected to the antenna pattern. The antenna unit further comprises a hollow cylindrical cover case covering the hollow cylindrical member and a shield member provided so as to cover the phase shifter pattern.