Measured Backscatter Modulation from Linearly Oscillating Metal Disks
ROME AIR DEVELOPMENT CENTER GRIFFISS AFB NY
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The work described in this report was carried out as part of the basic research program directed toward providing an understanding of the radar detection of agitated metals RADAM. The report describes an experimental equipment and measurement procedure that permits determination of the kind and amount of modulation introduced onto the backscattered electromagnetic signal by a vibrating or oscillating scattering target. Although discussed specifically in terms of equipment realization at 10 GHz, the techniques are general. Provision has been included for determining characteristics of the mechanical motion and correlating mechanical and electromagnetic results in the time and frequency domain. The results of a series of measurements of modulated backscatter cross sections due to a disk executing small rigid translational oscillations show the modulation introduced to be all phase modulation measured results are in good agreement with those calculated from a soundly-based theory. In addition, it is shown that the modulation amplitude is independent of modulation frequency, that the phase modulation introduced is directly proportional to the amplitude of the mechanical oscillation, and that the spectral components of the modulated signal are monotonically decreasing for simple sinusoidal motion.
- Electricity and Magnetism
- Radiofrequency Wave Propagation