Abstract: A gate structure includes a gate control housing, a gate member and a control system. The control system includes a first and a second connector. The second connector is detachably attached on the moving object, and includes a signal generating module. The first connector and the second connector are communicated through a predetermined radio frequency signal. The gate member is operated between a closing position and an opening position, wherein in the closing position, a distance between the first and the second connector is larger than a preset connecting distance and the gate member is closed for blocking access to the restricted area, wherein in the opening position, a distance between the first connector and the second connector is within the preset connecting distance and the gate member is actuated to move for allowing access to the restricted area by the moving object bearing the first connector.

Abstract: An alarm device for an automatic garage door includes a detecting circuit for producing a single negative pulse signal when a detector detects an opening motion of said garage door, an alarm controlling circuit for receiving said single negative pulse signal and producing an alarm signal, a "normal function" detecting circuit connecting to a garage door opening machine for producing a "normal opening" signal when said garage door is normally opened by said garage door opening machine, which is then changed to a "shut off alarm" signal provided to said alarm controlling circuit for preventing the production of said alarm signal, an alarm generating circuit for generating an alarm when said alarm signal is received, and a transformer circuit for providing low voltage for said alarm device. Accordingly, the alarm device for an automatic garage door can provide a warning alarm when said garage door is forced to open or damaged by bandits or burglars.