Continuously variable microstrip attenuator using directional coupler

Claim 1

A CONTINUOUSLY VARIABLE ATTENUATOR COMPRISING: A FIRST WAVE ENERGY TRANSMISSION LINE PORTION; A SECOND WAVE ENERGY TRANSMISSION LINE PORTION EXTENDING SUBSTANTIALLY PARALLEL TO SAID FIRST TRANSMISSION LINE PORTION, SAID FIRST AND SAID SECOND TRANSMISSION LINE PORTIONS BEING MOUNTED FOR CONTINUOUSLY VARIABLE RELATIVE LATERAL MOTION BETWEEN A FIRST POSITION IN WHICH SAID TRANSMISSION LINE PORTIONS ARE SUBSTANTIALLY COEXTENSIVE TO A SECOND POSITION IN WHICH SAID TRANSMISSION LINE PORTIONS ARE SUBSTANTIALLY DISPLACED; APERTURE MEANS BETWEEN SAID FIRST AND SECOND TRANSMISSION LINE PORTIONS FOR COUPLING SAID TRANSMISSION LINE PORTIONS TO ONE ANOTHER, THE DEGREE OF COUPLING ACROSS SAID APERTURE MEANS BEING PROPORTIONAL TO THE RELATIVE LATERAL DISPLACEMENT BETWEEN SAID TRANSMISSION LINE PORTIONS AND BEING VARIABLE FROM A MAXIMUM AT SAID FIRST POSITION TO A MINIMUM AT SAID SECOND POSITION, SAID APERTURE MEANS HAVING A LENGTH APPROXIMATELY EQUAL TO ONE-QUARTER OF THE MEAN OPERATING WAVELENGTH OF THE TRANSMITTED WAVE ENERGY; AND IMPEDANCE RESTORING MEANS COEXTENSIVE WITH THE LENGTH OF SAID APERTURE MEANS CARRIED BY EACH OF SAID TRANSMISSION LINE PORTIONS TO MAINTAIN THE IMPEDANCE OF SAID TRANSMISSION LINE PORTIONS AT A PRESELECTED VALUE WHEN SAID TRANSMISSION LINE PORTIONS ARE LATERALLY DISPLACED FROM SAID FIRST POSITION, THE IMPEDANCE RESTORING MEANS CARRIED BY SAID FIRST TRANSMISSION LINE PORTION COOPERATING WITH SAID SECOND TRANSMISSION LINE PORTION AND THE IMPEDANCE RESTORING MEANS CARRIED IN SAID SECOND TRANSMISSION LINE PORTION COOPERATING WITH SAID FIRST TRANSMISSION LINE PORTION.