Estimating Uncertainties of System Level RF Parameters of Transponder Spacecraft Payloads

This paper provides an overview of measurement uncertainties associated with a planar near-field test methodology for measuring typical system level characteristics of transceiver payloads. We describe a framework for analyzing the uncertainties when measuring these system level RF parameters in a near-field range. More specifically, saturating flux density (SFD), equivalent isotropic radiated power (EIRP), gain-to-noise temperature (G/T) and end-to-end gain vs. frequency are addressed. Results from a set of validation measurements, performed on a frequency converting simulated payload are used as baseline. A combination of analysis and direct measurements are presented to validate the measurement methodology for each parameter and estimate corresponding uncertainties. The contribution of this paper is the presentation of these methodologies and establishing an initial set of uncertainty boundaries to qualify the near-field test approach for this purpose.