Measurements of Complex Dielectric Constants of Paints and Primers for DSN Antennas: Part I

In past years, it was known that paint on reflector surfaces causes degradation of antenna gain and noise temperatures, but it was not known how much degradation occurs as a function of paint and primer thickness or frequency. This article presents an approach used to study the properties of paint by first measuring the complex dielectric constants of paint and primers at frequencies of interest. After the complex dielectric constants become known, theoretical calculations then can be made of degradation of antenna gain and noise temperatures due to paint/primer thicknesses as functions of incident-wave polarization and incidence angles in free space. Tables are presented for measured complex dielectric constants over a frequency range from 24 through 34 GHz for (1) the paint and primer currently being used on DSN antenna main and subreflector surfaces and (2) paint and primer that are candidate replacements.