Measurements of K-Band Radiation in the Vicinity of Air-Styrofoam Discontinuities,
OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS ANTENNA LAB
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Field pattern measurements with Styrofoam were made to determine the cause of the severe variations in the field pattern behind the lens and to seek means of modifying the lens to reduce or eliminate them. The experiments indicated that 1 the variations may be attributed to the slits which run through the lens parallel to the direction of propagation 2 simple modifications in the lens, such as the use of Styrofoam wedges in the lens faces, will not significantly reduce these disturbances and 3 if the adjacent blocks in the assembled lens fit closely together, the variations will be reduced in amplitude to a tolerable range. Attempts were made to construct the lens to fit the adjacent blocks as close together as possible. Inspection of the faces of the lens when it was first assembled indicated that adjacent blocks had no significant separation a similar examination at a later time showed the presence of wide spaces between blocks. Styrofoam shrinks or warps after it has been machined. This aging effect is noticeable for a period of about 3 wk after the initial processing.