Citation
Abstract
This article quantifies the required antenna separation to observe independent multipath fading on direct-with-Earth links between a lander and/or rover on a planetary body (e.g., the Moon) and an Earth station. Using a simple ray-based model valid for operation at high frequencies (S-band and above), we show that the required antenna separation to achieve uncorrelated fading is much larger than the half-a-wavelength value typically cited in the literature. We also show that operation at grazing angles exacerbates the problem, especially in the downlink direction, requiring Earth stations to be separated by hundreds of kilometers to achieve diversity. Therefore, we conclude that dual coverage from Deep Space Network (DSN) antennas within the same deep space complex is unlikely to provide “protection” against multipath effects. To build confidence in the analytical results presented in this article, we discuss the two empirical data sets available from the Chandrayaan-3 and Intuitive Machines 1 mission. The former is used to show signal correlation at two DSN stations within the same complex (i.e., intra-site channel correlation), while the latter provides information for stations in different DSN sites (inter-site channel correlation).
Keywords
Details
- Volume
- 42-243
- Published
- November 15, 2025
- Pages
- 1–19
- File Size
- 1.2 MB