VHF/UHF Stellar Calibration Error Analysis

Abstract

A statistical error analysis is performed to determine the degree of uncertainty encountered when calibrating steerable VHF /UHF receiving antennas with the stellar calibration method. The analysis considers the propagation of precision error indexes. It is shown that an antenna gain calibration by the stellar method has a one-sigma (1σ) uncertainty of ±0.65 dB at 1440 MHz (L-band), and ±0.8 dB (1σ) at 136 MHz (VHF). Somewhat increased precision can be achieved by monitoring the antenna gain-to-noise temperature (G/T) ratio at a station; a worst-case uncertainty of ±0.4 dB (1σ) can be realized at both L-band and VHF. Finally, field test measurements of antenna gain, obtained at 136 MHz in the NASA space tracking and data acquisition network (STADAN), demonstrate an uncertainty of ±1.0 dB, or less, which effectively confirms the analytical result.