Paraboloidal antenna with compensating elements to reduce back radiation into feed

Claim 1

A BROADBAND DIRECTIVE ANTENNA COMPRISING A MAIN PARABOLIC REFLECTOR, AN OUTWARDLY FLARING HORN MOUNTED ON THE AXIS OF THE PARABOLODIAL SURFACE OF SAID REFLECTOR AND EXTENDING INTO THE INTERIOR OF SAID REFLECTOR, SAID HORN HAVING A THROAT AND A WIDER MOUTH WITH SAID MOUTH LOCATED IN THE INTERIOR OF THE MAIN REFLECTOR, A METALLIC COVER IN THE FORM OF A FRUSTUM OF A CONE EXTENDING FROM THE MOUTH OF THE HORN BACK TO THE INNER SURFACE OF THE MAIN REFLECTOR, ANOTHER REFLECTOR SUBSTANTIALLY HYPERBOLOIDAL IN SHAPE FACING SAID HORN MOUTH, SAID OTHER REFLECTOR BEING APPRECIABLY SMALLER IN SIZE THAN THE MAIN PARABOLIC REFLECTOR AND HAVING ITS WIDEST DIMENSION SUBSTANTIALLY EQUAL TO THE WIDEST DIMENSION OF SAID FRUSTUM, THE DIMENSIONS OF SAID HORN AND OTHER REFLECTOR BEING SUCH THAT THERE IS A POINT SOURCE OF SPHERICAL WAVES AT THE THROAT OF THE HORN AND A VIRTUAL POINT SOURCE OF SPHERICAL WAVES BEHIND THE OTHER REFLECTOR, AND A COMPENSATING ELEMENT MOUNTED ON THE CENTRAL PART OF SAID OTHER REFLECTOR FACING THE MOUTH OF THE HORN FOR REFLECTING BACK TOWARD THE HORN WAVES WHICH ARE EQUAL IN APLITUDE BUT OPPOSITE IN PHASE TO THE WAVES WHICH ARE REFLECTED BACK TOWARD THE HORN FROM SAID OTHER REFLECTOR.