Broadband microwave bulk acoustic delay device

Electroacoustic apparatus comprising:

• an ultrasonic transmission medium having a first and second surface,
• first and second transducers adapted to convert microwave energy into bulk mode ultrasonic elastic wave energy, and vice versa, located on said first surface,
• microwave input means connected to said first transducer,
• microwave output means connected to said second transducer,
• said first transducer and ultrasonic transmission medium adapted for propagation of bulk mode ultrasonic elastic wave energy in said ultrasonic transmission medium,
• said second surface being positioned to reflect ultrasonic elastic wave energy incident upon said second surface,
• said second transducer located within the area incident of a first reflected ultrasonic elastic wave from said second surface,
• said first reflected ultrasonic elastic wave incident upon said first surface being spread over a larger area than the area of the initially propagated ultrasonic elastic wave due to propagation in the Fraunhofer field region wherein said microwave input means is a coplanar transmission line.

Electroacoustic apparatus comprising:

• an ultrasonic transmission medium having a first and second surface,
• first and second transducers adapted to convert microwave energy into bulk mode ultrasonic elastic wave energy, and vice versa, located on said first surface,
• microwave input means connected to said first transducer,
• microwave output means connected to said second transducer,
• said first transducer and ultrasonic transmission medium adapted for propagation of bulk mode ultrasonic elastic wave energy in said ultrasonic transmission medium,
• said second surface being positioned to reflect ultrasonic elastic wave energy incident upon said second surface,
• said second transducer located within the area incident of a first reflected ultrasonic elastic wave from said second surface,
• said first reflected ultrasonic elastic wave incident upon said first surface being spread over a larger area than the area of the initially propagated ultrasonic elastic wave due to propagation in the Fraunhofer field region wherein said microwave output means is a coplanar transmission line.

Electroacoustic apparatus comprising:

• an ultrasonic tranmission medium having a first and second surface,
• first and second transducers adapted to convert microwave energy into bulk mode ultrasonic elastic wave energy, and vice versa, located on said first surface,
• microwave input means connected to said first transducer,
• microwave output means connected to said second transducer,
• said first transducer and ultrasonic transmission medium adapted for propagation of bulk mode ultrasonic elastic wave energy in said ultrasonic transmission medium,
• said second surface being positioned to reflect ultrasonic elastic wave energy incident upon said second surface,
• said second transducer located within the area incident of a first reflected ultrasonic elastic wave from said second surface,
• said first reflected ultrasonic elastic wave incident upon said first surface being spread over a larger area than the area of the initially propagated ultrasonic elastic wave due to propagation in the Fraunhofer field region wherein the first transducer electrode dimensions are adjusted in size to provide a diffraction loss at the highest frequency of a desired broadband which is equal to the minimum propagation loss at the lowest frequency of said desired broadband whereby the insertion loss of the apparatus is relatively constant from the said lowest frequency to the said highest frequency.