Elastic wave radiator and detector

Claim 1

APPARATUS FOR USE IN ELASTIC WAVE RADIATION AND RECEIVING SYSTEMS COMPRISING, IN COMBINATION, A CYLINDRICAL ELEMENT MADE OF A MATERIAL CAPABLE OF SUSTAINING THE PROPAGATION OF ELASTIC WAVES THERETHROUGH; MEANS COUPLED TO ONE END OF SAID ELEMENT FOR INTRODUCING PERIODIC ELASTIC WAVES THEREIN WHEN EXCITED; A SERIES OF ANNULAR FINS PROJECTING FROM THE OUTER WALL SURFACE OF SAID CYLINDRICAL ELEMENT AND EQUALLY SPACED THEREALONG WITH THE SEPARATION BETWEEN ADJACENT FINS BEING LESS THAN ONE QUARTER WAVE LENGTH OF SAID PERIODIC ELASTIC WAVES AS MEASURED IN THE MEDIUM SURROUNDING SAID CYLINDRICAL ELEMENT, EACH PAIR OF ADJACENT FINS COUPLING A PORTION OF THE ELASTIC WAVES INTRODUCED INTO SAID CYLINDRICAL ELEMENT INTO SAID SURROUNDING MEDIUM WHEREBY THE AMPLITUDE OF SAID INTRODUCED ELASTIC WAVES PROGRESSIVELY DIMINISHES AS SAID WAVES PROPAGATE TOWARD THE OPPOSITE END OF SAID CYLINDRICAL ELEMENT, SUCCESSIVE FINS OF SAID SERIES EXTENDING PROGRESSIVELY GREATER DISTANCES OUTWARDLY FROM SAID OUTER WALL SURFACE WITH THE FIN IMMEDIATELY ADJACENT SAID ONE END EXTENDING THE SHORTEST DISTANCE THEREFROM WHEREBY EACH PAIR OF ADJACENT FINS COUPLES EQUAL AMOUNTS OF THE ELASTIC WAVES INTO SAID SURROUNDING MEDIUM, SUCCESSIVE FINS OF SAID SERIES ALSO HAVING PROGRESSIVELY DECREASING THICKNESS WITH THE FIN IMMEDIATELY ADJACENT SAID ONE END HAVING THE GREATEST THICKNESS WHEREBY THE PHASE VELOCITY OF SAID ELASTIC WAVES IS MAINTAINED CONSTANT AS SAID ELASTIC WAVES PROPAGATE TOWARDS SAID OPPOSITE END OF SAID CYLINDRICAL ELEMENT.