Accession Number:

ADA052706

Title:

Harmonic Operation of SAW Electromagnetic Transducers,

Descriptive Note:

Corporate Author:

ROME AIR DEVELOPMENT CENTER HANSCOM AFB MASS DEPUTY FOR ELECTRONIC TECHNOLOGY

Personal Author(s):

Report Date:

1978-03-28

Pagination or Media Count:

5.0

Abstract:

For many NDE applications, coverage of an extremely broad range of frequencies is required to characterize a defect or gradient. Non-contact SAW Electromagnetic transducers appear to be restricted to relatively small fractional bandwidths by their structure and low coupling. One solution to this problem is overtone operation of the transducers at their odd harmonics which present models do not predict adequately. This situation motivated the derivation of a new equivalent circuit model based on a description of the dynamic fields surrounding transducer conductors in which the current distributions are allowed to vary. The new results, while in agreement for fundamental frequency operation with the earlier flat field theory, differ in harmonic prediction. Data favors the new theory. As a design example, we present data corrected for propagation losses and variations in our electronics for an unmatched electromagnetic transducer F .376 MHz with a constant insertion loss within 2 dB out to the seventh odd harmonic as predicted by the new theory. Author

Subject Categories:

  • Acoustic Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE