The Kennaugh´s concept of the inversion point inside the Poincare sphere model of the scattering matrix and further developments of his ideas

Edward Morton Kennaugh (1920-1983), in his last paper (IEEE Trans. Antennas and Propag., vol.AP-29, no.2, p.412-13, 1981), recalled his geometrical interpretation of polarization dependence of the radar cross-section (RCS). That dependence had been discovered by him and announced for the first time in his two Ohio State University Antenna Laboratory reports of the years 1950 and 1951. Kennaugh noted that his results ´described 30 years earlier, seemed to have been generally overlooked´. Now we can observe that those results, so simple and so important for practical applications, have been ´generally overlooked´ during the next 20 years also. The aim of this paper is to recall his original ´inversion point´ concept as a corner-stone of the Poincare sphere model of the scattering matrix and to present some further developments of his ideas based on that concept.