Microwave Scattering From an Agitated Water Surface.
Abstract
An investigation was conducted into the detection of low frequency sound waves by the reflection of 8 mm microwaves from the water surface. For acoustic waves of moderate intensity, the ratio of amplitude of water motion to the wavelength of 8 mm microwaves is of the order of 0,0003. Due to limitations of time and available equipment, detection of such small motion was judged to be impractical within the scope of the project. An experiment which simulated the actual sound wave problem with larger amplitudes of water surface vibration was constructed. Spectral analysis techniques using the Fast Fourier Transform were applied to the detected phase fluctuation of the reflected microwave beam to separate the frequencies of water surface vibration from the spectrum of surface roughness. The results of the experimental measurements indicate that the use of shorter wavelengths, such as are available from lasers, and/or advanced phase detection techniques will make the detection of sound waves in water possible from reasonable distances, if the acoustic frequency is greater than the highest frequencies present in the water roughness spectrum. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 19, 1968
- Accession Number
- AD0848244
Entities
People
- D. J. Angelakos
- H. Stuart Hutchins Iv.
Organizations
- University of California, Berkeley