I. Introduction
A synthetic aperture radar (SAR) can work in all weather and all time, and it has become an important observation tool in the field of remote sensing. With the development of the SAR technique, the resolution of an SAR image has been greatly improved. It is of great significance to monitor the running state of a high-voltage power grid using the high-resolution SAR images. The detection of power transmission towers is a key step for power grid monitoring.