© 2025 by the authors. Licensee MDPI, Basel, Switzerland.Sánchez-Sevilleja, SarayPoyatos Martinez, DavidMasa-Campos, J.L.Aragón Fernández, Víctor MiguelRodríguez Prieto, José AntonioSantiago Pé, Amaia2026-03-232026-03-232025-02-18Sensors 2025, 25(4): 1237https://www.mdpi.com/1424-8220/25/4/1237https://hdl.handle.net/20.500.12666/1815An S-band antenna has been designed, developed, measured, space-qualified, and integrated into the INTA ANSER satellite constellation and the future ANSER-AT mission. This antenna will be part of the space-to-ground communication link for the constellation, which consists of one Leader and two Followers. The novel antenna, mounted on the Leader, has been designed and manufactured with materials and processes specifically tested for space. It features dual circular polarization over a wide band without requiring a phase-shifting network, making it very compact and straightforward. Additionally, its gain patterns are highly stable within the desired band, improving its link capacity compared to the UHF monopole alternative used in the previous Leader. Currently, the antenna has been qualified and installed on INTA’s Leader-S, set to launch in January 2025, as well as on the future ANSER-AT mission.engAttribution 4.0 Internationalhttps://creativecommons.org/licenses/by/4.0/constellationclusterCubeSatantennaMPApolarizationaxial ratioinfo:eu-repo/semantics/article10.3390/s250412371424-8220info:eu-repo/semantics/openAccess