Design and Performance of the Monopulse Pointing System of the DSN 34-Meter Beam-Waveguide Antennas

This article describes the design, analysis, and performance prediction of a monopulse pointing system in a 34-m beam-waveguide antenna of the Deep Space Network (DSN). While the basic concept of monopulse pointing is not new, its application in the DSN is novel in two ways: flrst, the large antenna structure made necessary by the extremely weak signal environment; and second, the use of the single monopulse feed at 31.8 to 32.3 GHz (Ka-band) frequencies. The conventional aircraft radar application has a higher signal-to-noise ratio (SNR) with a fast, hostile tracking scenario. The DSN application requires precise antenna pointing to minimize pointing loss, maximize amplitude stability, and track very low-SNR signals from a very distant spacecraft with a well-predicted trajectory. The combination of the large antenna size, the low SNR, and the precise pointing requirements makes the monopulse implementation in the DSN a challenging task.