On Orbit Measurement of TOPEX/POSEIDON Altimeter Antenna Pattern

The NASA and CNES altimeters on the TOPEX/POSEIDON satellite share a 1.5-meter antenna. Early data suggested that the beam was broader than measured preflight. As corrections which depend on values from the tail of the waveform have been compensated for deviations from the preflight measurements, no appreciable effect on the final data is expected.