# C-SAR
*sensor . products*

Active C-band Synthetic Aperture Radar operating at 5.405 GHz (about 5.55 cm wavelength), sole imaging payload of the ESA Sentinel-1 satellite series under the Copernicus programme. Instrument built by Airbus Defence and Space (Friedrichshafen); satellite platform built by Thales Alenia Space (distinct role). Active phased-array antenna 12.3 by 0.821 metres. Four imaging modes: Interferometric Wide Swath (IW) is the operational workhorse at 250 km swath / 5 by 20 m resolution dual-pol; plus Extra Wide (EW, 400 km), Stripmap (SM, 80 km, ERS/Envisat heritage), and Wave (WV, open ocean profiling). Operational on Sentinel-1A (2014), Sentinel-1C (Dec 2024), Sentinel-1D (Nov 2025); Sentinel-1B retired August 2022 after a power anomaly. Backbone of RADD forest disturbance alerts.

## Specifications
- **product status**: operational
- **manufacturer**: airbus-ds
- **sensor**: {"instrument_family":"sar","measurement_principle":"active","frequency_band":"C","centre_frequency_mhz":5405,"chirp_bandwidth_mhz":100,"polarisation_modes":["HH","VV","HH+HV","VV+VH"],"incidence_angle_range_deg":[18.3,47],"nesz_db":-22,"antenna_length_m":12.3,"transmit_power_w":4368,"swath_km":250,"modes":[{"name":"IW","resolution_range_m":5,"resolution_azimuth_m":20,"swath_km":250,"polarisation":"VV+VH or HH+HV"},{"name":"EW","resolution_range_m":20,"resolution_azimuth_m":40,"swath_km":400,"polarisation":"VV+VH or HH+HV"},{"name":"SM","resolution_range_m":5,"resolution_azimuth_m":5,"swath_km":80},{"name":"WV","resolution_range_m":5,"resolution_azimuth_m":20,"swath_km":20}],"notes":"PRF 1000 to 3000 Hz programmable. Pulse width 5 to 100 microseconds programmable. Bandwidth 0 to 100 MHz programmable. IW mode uses TOPSAR burst-mode across three sub-swaths."}
- **last verified date**: "2026-05-18T00:00:00.000Z"
- **verified by**: sw
- **claim status**: agency-verified
- **deployment context**: orbital

## Compositional position
- sentinel-1a (missions) --[mission_payloads]--> C-SAR
- sentinel-1c (missions) --[mission_payloads]--> C-SAR
- sentinel-1d (missions) --[mission_payloads]--> C-SAR

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Source: https://eo-atlas.org/products/sensor/c-sar
Maintainer: SpectraWorks B.V. (CC-BY 4.0)