Microwave filters and multiplexing networks are frequently found in different space applications: Telecommunication, Navigation, and Earth Observation satellites. In this talk an overview of requirements for passive microwave hardware used in all these payloads will be performed. Broadband and Broadcast Satellite System payload architectures will be analysed and the derived requirements for filters and multiplexers will be presented. Systems such as radiometers, scatterometers, altimeters, radars, etc. will be reviewed highlighting the main features regarding filters, multiplexers, isolators and other passive hardware used in such applications. The latest trends and future requirements for passive equipment within forthcoming satellite systems (including payload flexibility) will be also addressed.