Posty: 143 #2069971
Moze ktoś z Was m a ochotę podjć się takiego wyzwaia? Szczegółów nie znam... ale w ogolności temat, na ktory sa fundusze jest następujący:
DESIGN AND ANALYSIS OF X-BAND TT&C AND K-BAND LOW GAIN ANTENNAS FOR FUTURE LEO MISSIONS - EXPRO PLUS
Open Date: 13/02/2015
Closing Date: 27/03/2015
Department: Science, Appl & Future Technologies Dept
The objective of the activity is the detailed design and analysis of: - Telemetry, Tracking & Command (TT&C) antennas with close to hemispherical pattern in X-Band. This is a transmit and receiver antenna - and Data Downlink (DDL) antennas with isoflux pattern in K-band for future Low Earth Orbit (LEO) missions. This is a transmit only antenna. The output of the activity will be antenna designs of sufficient detail to enable a direct follow-on of an EM development activity. During the activity antenna solutions with: - separate X-band TT&C and K-band DDL antennas - and also dual frequency designs, which enables the combination of the nadir TT&C and DDL functions, will be traded-off with regard to the antennas performance, satellite accommodation, manufacture, RF Interference,etc. The most promising solution will be taken forward to the detailed design phase of the activity. Background: At the moment all European Earth Observation LEO satellites use S-band and X-band almost exclusively for TT&C and DDL respectively. Consequently, these bands are becoming very congested. It is also expected that a sizable number of future EO missions will have a requirement to uplink large amounts of data for operation plans and dynamic spacecraft software modifications for which the coordination in S-Band will become increasingly difficult due to the limited bandwidth allocation in S-Band and the extensive use of this band. At the WRC-15, a new X-Band frequency allocation by the International Telecommunications Union (ITU) for the Earth Exploration Satellite Service (EESS), that include Low Earth Orbit satellites, for TT&C is planned for the range 7190-7250 MHz for the uplink. This new uplinkcan be used in combination with the existing EESS allocation in 8025-8400 MHz for the downlink. Regarding DDL, the current allocationin X-band is limited to 375 MHz, which also imposes serious limitations on the data rate. The ITU allocates four times more bandwidth in the 26 GHz K-band (i.e. 25.5 to 27 GHz) for EESS (space-to-ground) links . Also, current X-Band isoflux designs are quite large(around 500mm diameter), but X-band close to hemispherical pattern designs, and K-band isoflux designs can be done with smaller antennas that may make them more suitable for smaller missions.