Microwave ultrasonic delay line

Claim 2

A microwave ultrasonic delay line comprising, in combination; an electroacoustical transducer including at least two electrodes; a delay medium mounted at one of its ends in transfer relationship with said transducer; thin films each in the order of 0.1 acoustical wavelengths of the energy propagating through the delay medium disposed on said other end of said medium to provide zoned acoustical lenses for narrow bands of frequencies to refocus the acoustical wave propagating through said said delay medium to said area of the transducer over which the electric field is normal to the surface of said electrodes; said area being substantially smaller than the cross-sectional area of said delay medium.

Claim 3

A microwave ultrasonic delay line comprising, in combinaTion; a delay medium; an electroacoustical transducer including at least two electrodes; one electrode being of substantially the same cross-sectional area as said delay medium, the other electrode being substantially smaller in cross-sectional area to provide an active area of said transducer over which the electric field is normal to the surface of the transducer; said delay medium mounted at one of its ends in transfer relationship with said one electrode, the other end of said medium being shaped to focus the acoustic energy to return to said area of said transducer over which the electric field is normal, said area being substantially smaller than the cross-sectional area of said delay medium whereby the resistive component of the load impedance presented by said transducer is increased in magnitude inversely proportional to the reduction in size of the area of said transducer over which the electric field is normal; and thin film each in the order of one-tenth of the acoustical wavelength of the energy propagating through the delay medium disposed on said other end of said medium for reflecting and focusing the acoustical wave propagating through said delay medium to said active area.

Claim 4

A microwave ultrasonic delay line comprising, in combinaTion; a delay medium; an electroacoustical transducer including at least two electrodes; one electrode being of substantially the same cross-sectional area as said delay medium, the other electrode being substantially smaller in cross-sectional area to provide an active area of said transducer over which the electric field is normal to the surface of the transducer; said delay medium mounted at one of its ends in transfer relationship with said one electrode, the other end of said medium being shaped to focus the acoustic energy to return to said area of said transducer over which the electric field is normal, said area being substantially smaller than the cross-sectional area of said delay medium whereby the resistive component of the load impedance presented by said transducer is increased in magnitude inversely proportional to the reduction in size of the area of said transducer over which the electric field is normal; and thin film each in the order of one-tenth of the acoustical wavelength of the energy propagating through the delay medium disposed on said other end of said medium for reflecting and focusing the acoustical wave propagating through said delay medium to said active area.