Detection of properly positioned movable objects

DETAILED DESCRIPTION The present invention provides a novel apparatus and a novel method for determining when a movable object is in a predetermined position.
The present invention also provides a means for determining the location of a further object relative to or carried by the movable object.
It is a feature of the present invention that the location of a movable object is determined by the reception of electromagnetic radiation passing near or through the movable object from a source remote from the movable object.
In addition, it is a feature of the present invention to use electromagnetic radiation which is polarized when it leaves the source and subsequently rotated as the radiation passes near or through the movable object.
The detector of the present invention is adapted to receive only rotated radiation so that substantially only that radiation which is rotated by the movable object being at the predetermined position is detected.
It is also a feature of the present invention to use a microwave beam generation and detection system that can be interconnected with a microprocessor control system so that the radiation can be selectively generated and so that the reception of the detected signal can be properly interpreted.
Obviously, the microprocessor control system can also be coordinated with other types of microwave and other detection systems, such as systems used for detecting the presence of people or, for example, the failure to properly close the door of an automobile to be transported.
It is another feature of one embodiment of the present invention to make use of the theory and principals of wave guides, but without the necessity of using expensive, fragile, precisely dimensioned, conventional waveguides.
Conventional waveguides are simply highly conductive metallic tubes inside which electromagnetic waves can propagate through reflection from the inner surfaces.
In order to minimize loses in conventional waveguides and to insure that the frequencies of the propagating wave are not cut off, the internal surfaces are usually made from copper and coated with gold or other precious metal and the tolerances of the internal and external dimensions are kept very small