Correction for quadrature errors

In high bandwidth radar systems it is necessary to use quadrature devices to convert the signal to/from baseband. Practical problems make it difficult to implement a perfect quadrature system. Channel imbalance and quadrature phase errors in the transmitter and the receiver result in error signals, which appear as self-clutter in the radar image. When digital techniques are used for generation and processing or the radar signal it is possible to reduce these error signals. In the paper the quadrature devices are analyzed, and two different error compensation methods are considered. The practical implementation in the Danish polarimetric SAR system, EMISAR, is presented, and measured results are given.