A movable seat of a vertical curtain is disposed in an upper rail and is provided for suspending vertical curtain blades. The dual-band antenna includes a grounded portion, a feeding portion, and a radiation body. The deflection angles of the left and right lamps are differentiated in accordance with the speed change of an automobile. The velocity distribution in the geologic formation andor the geometry of the interface between the sedimentary layers can be known otherwise or determined by means of the method.