SYNTHETIC APERTURE RADAR FREQUENCY SCAN FOR TIME-OF-ECHO COMPRESSION IMAGING MODE

The paper details a SAR imaging mode named frequency SCan On Receive and Transmit (fSCORT) where, a narrow, frequency-scanning transmit antenna beam is formed illuminating the swath of interest from far to near range. Similarly, the frequency-scanning receive antenna beam collects the return echo signal reflected from the ground. It is shown that the imaging technique trades (sacrifices) range resolution for (improved) signal-to-noise ratio, azimuth resolution, and swath width. It is shown that the (transmit) pulse duty cycle may be significantly increased over what is common for pulsed SAR systems, allowing for a lower peak-to-average transmit power ratio. The imaging mode is especially suitable for space-borne SAR systems operating at high carrier frequencies, such as X- or Ka-band where other advanced digital beam-forming techniques may not be feasible due to technology limitations, while, on the other hand, a large system bandwidth may be available. The paper provides a mathematical model describing fSCORT operation parameters. Closed expressions for the mode performance parameters, such as range resolution, echo window length, etc. are derived.