Several imaging modes of polarimetric SAR

In recent years , Polarimetric synthetic aperture radar (POLSAR) In feature classification 、 The environmental monitoring 、 Target detection and other fields have been widely used . Polarization SAR The polarization scattering matrix of the target is obtained by transmitting and receiving electromagnetic waves with different polarization directions , Then the polarization scattering characteristics of different ground objects are studied . At present, polarimetric synthetic aperture radar can be divided into single polarization according to the different polarization channels of transmitting and receiving 、 Bipolarization 、 Simple polarization 、 Full polarization equipolarization system . In terms of information quantity , Single polarization 、 Bipolarization 、 The polarization information obtained by the four modes of simple polarization and full polarization is more and more abundant , However, the system is becoming more and more complex . Fully polarized systems are subject to design and maintenance complexity 、 Power consumption 、 Coverage and data download , They restrict full polarization SAR Application .

1. Single polarization

Single polarization SAR The system has a single transmitting channel and a single receiving channel , The obtained polarization information is HH or VV, Early synthetic aperture radar (SAR) was single polarization mode , Such as the US ocean satellite series SEASAT、 European remote sensing satellite ERS-1(European remote-sensing satellite, ERS)、 Japan earth resources satellite JERS-1(Japanese earth resources satellite,JERS)、 Canadian satellite Radarsat-1 etc. .

2. Bipolarization

The dual polarization system has a single transmitting channel and a dual receiving channel , There are three different modes , The polarization information obtained are HH/VV or HH/HV or VV/VH. Canadian Radarsat-2 And Germany. TerraSAR-X Both have dual polarization mode .

3. Simple polarization

Simple polarization (compact-pol) It is a recently developed polarization mode , It emits electromagnetic waves in one polarization direction , Receive electromagnetic waves in two polarization directions . According to the polarization type of transmitted and received polarization waves , There are three modes of simple polarization ：Π/4 Pattern 、 Double circular polarization mode and mixed polarization mode . India's Mini-SAR、 In the United States Mini-RF（miniature radio-frequency） Lunar exploration satellites all adopt double circular polarization mode , Canada's Radar Satellite Constellation program also lists the dual circular polarization mode as a polarization selection method .

4. Full polarization

The full polarization system has two transmitting channels and two receiving channels , The obtained polarization information is full polarization information ：HH/HV/VH/HH. Specially , If reciprocity assumption is considered , Then the received message is HH/HV/VV, It is called four polarization mode .1985 year ,NASA/JPL The first airborne full polarization SAR System ,1994 American space shuttle SIR-C Fully polarized spaceborne SAR, Later, Japan's advanced land observation satellite ALOS-PALSAR And Canadian Radarsat-2 All are full polarization synthetic aperture radar .
notes ： The article is excerpted from 《 Synthetic aperture radar intelligent interpretation 》 Xu Feng et al