Title :
The use of impedance standards in free space reflection coefficient measurements
Author :
Smith, F.C. ; Chambers, Barry ; Bennett, J.C.
Author_Institution :
Sheffield Univ., UK
Abstract :
The standards used in free space reflection coefficient (S11) measurements are examined. As with all standards, the response of a free space impedance standard has to be calculable. The impedance standards discussed use transmission line analogy (TLA) techniques to determine their reflection coefficient. However, the TLA can only derive approximate values of reflectivity; to calculate a more accurate value of a standard´s reflectivity a model has been developed, based on the Geometric Theory of Diffraction (GTD), which calculates the reflection coefficient of a standard so as to include the effects of finite sample size and arbitrary illumination. Some preliminary results from the GTD model are presented
Keywords :
electric impedance measurement; electromagnetic wave diffraction; electromagnetic wave reflection; measurement standards; microwave reflectometry; transmission line theory; GTD model; Geometric Theory of Diffraction; arbitrary illumination; finite sample size; free space measurements; free space reflection coefficient; impedance standards; radar absorbing material; reflection coefficient measurements; transmission line analogy;
Conference_Titel :
Low Profile Absorbers and Scatterers, IEE Colloquium on
Conference_Location :
London
