Accession Number : AD0491313

Title :   WATER RIPPLE ANALOGUE OF ELECTRO-MAGNETIC WAVE PROPAGATION,

Corporate Author : VERMONT UNIV BURLINGTON

Personal Author(s) : Walbridge, Nelson L. ; Smith, Howard M., Jr. ; Woodward, Lloyd A.

Report Date : SEP 1952

Pagination or Media Count : 83

Abstract : An oscillator controlled a vibrating probe used to generate ripples on the surface of water in a tray with a glass bottom. The same oscillator controlled the pulsing of light which passed up through the tray. The ripples acting as lenses focused the light on a ground glass screen. A meniscus which was convex when viewed from above was produced around the head of the probe. This arrangement produced better ripples. A methoc of coincidence of images was developed which applies to attenuated ripples. This method and the use of an auxiliary lens improved the accuracy of measurement of amplitudes particularly for small ripples. Several feeds including dipole arrays were simulated and the field patterns were measured. The results of experiments on reflection can be explained by the assumption of a 180 degrees phase change at a line behind the actual reflector. Ripple tanks can be used in the study of radar antennas since no unsolvable problems have been encountered in the experimental development of the analogy. (Author)

Descriptors :   (*ELECTROMAGNETIC RADIATION, WAVE PROPAGATION), LIGHT, OSCILLATION, WATER, SURFACES, REFRACTION, RADAR ANTENNAS, MEASUREMENT, SIGNAL GENERATORS, RADAR PULSES.

Distribution Statement : APPROVED FOR PUBLIC RELEASE