Paint vs. Performance -- The Effects of Paint on Large Aperture Ka-Band Antennas

Non-uniform solar loading due to non-standard paint can cause a loss in earth terminal antenna gain and pointing inaccuracies due to dish defocusing, surface distortion and other changes in the structural geometry. Furthermore, paint and primer thickness less than a mil (one thousandth of an inch) is known to adversely affect the noise temperature, gain, and polarization isolation on high performance antennas [1]. In this paper, we describe the technical approach used to assess the effects of paint on an 18 m parabolic antenna. Using thermal and mechanical analysis based on the reflectivity and absorptivity properties of paint, we calculate the degradation on beam spreading and beam pointing losses in two pointing modes (Monopulse, and NORAD). Results of the analysis are used to show that end-to-end system performance (bearer traffic and command link availability margin), ground service availability, and Two Line Element set integrity can be maintained with an appropriate paint selection.