THE QUALITY OF THE LINCOLN CALIBRATION SPHERE
Abstract
Due to the relatively high background noise level of the radar range used to measure the Lincoln Calibration Sphere (LCS) before launch, the upperbound estimates of the backscattering cross section variation made at the time included a large contribution generated by the range itself. By comparing the range measurements and the mechanical measurements made on the LCS with measurements made on three other similarly constructed spheres, a refined estimate of the quality of the LCS is made. The comparison makes use of more precise range and mechanical measurements made on the other three spheres and of an application of perturbation theory to compute the variation of cross section from the mechanical measurements. The unexpectedly large signal scattered by the equatorial joint is an unwelcome addition to the backscattered field and is discussed in some detail. It is concluded that, at all frequencies below about 25 GHz, the r.m.s. deviation in backscattering cross section is not greater than 0.15 db, and that the average backscattering cross section differs from that of a perfect sphere of radius 0.56469 m by an amount which is small compared with the r.m.s. deviation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 22, 1966
- Accession Number
- AD0638442
Entities
People
- Michael L. Burrows
Organizations
- Massachusetts Institute of Technology