PRISM

PLIS can measure the surface backscatter at HH, HV, VH, and VV polarisations. The PLIS is composed of two “main” 2x2 patch array antennas inclined at an angle of 30° from the horizontal to either side of the aircraft to obtain push broom imagery over a cross track swath of +/- 45°. Both antennas are able to transmit and receive at V and H polarisations. The antenna’s two-way 6-dB beam width is 51°, and the antenna gain is 9 dBi ± 2 dB. In the cross-track direction, the antenna gain is within 2.5 dB of the maximum gain between 15° and 45°. PLIS has an output frequency of 1.245-1.275 GHz with a peak transmit power of 20 W. At the start and end of PRISM-21, PLIS is calibrated using three Polarimetric Active Radar Calibrators (PARCs) located close to the airport. During each flight, PLIS is also calibrated using five Passive Radar Calibrators (PRCs) and a forest site within the study area.