Abstract
Integrated Doppler measurement is one of the major methods for tracking a planetary space vehicle. To study the lunar gravity field precisely, the SELENE project is to measure the Doppler frequency of the spacecraft (s/c) radio signal with an accuracy of 1 mHz, or of 0.1 mm/s of range rate. Also, the Doppler measurement should be done with a data rate of everyfew tens seconds. Nonlinear phase pattern of the s/c antenna together with s/c spin will make erroneous Doppler measurements. Two types of antennas i.e. crossed-dipole and micro-strip are assumed for the spacecraft-borne antenna and the effects on Doppler measurements were investigated. Due to the s/c spin and antenna phase characteristics, three kinds of errors, i.e., a constant component, a periodical component with spin rate and higher order harmonic components will appear in Doppler measurement. Methods to remove those errors have been mentioned.
