Sp-461 ers-envisat Symposium

Replica Calculation

A replica of the chirped pulse is calculated from a complete calibration row cycle using the P1/P1a, P2 and P3

measurements, the ground characterized row patterns and the external characterization data. This is also typically

updated every 5 to 35 seconds.

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ANTENNA PATTERN CHARACTERIZATION

In order to provide the required image quality, the two-way antenna beam pattern should be known to a high degree of

accuracy (0.1dB). The transmit and receive antenna patterns have been accurately measured on ground for all eight

beams (IS1-IS7 and SS1) and both horizontal and vertical polarizations. The radiating performances of the antenna were

measured in the new Large Planar Near Field Range at Astrium Ltd (Portsmouth). Full characterization was performed:

8 beams, two modes (transmit and receive), two polarizations (V and H), in copolar and crosspolar components.

Example patterns are shown in figures 3 and 4.

In-flight the elevation beam patterns will be re-determined using several techniques:

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Images taken over the Amazonian rain forest