Frequency Scan for Time-of-Echo Compression in SAR Systems

Abstract

The development of synthetic aperture radar (SAR) instruments at higher carrier frequency is motivated, among others, by the relative wavelength scaling, which provides an increased bandwidth and reduced physical dimensions of the RF hardware, for the same coverage. The later causes a reduced area and a high length-to-height aspect ratio of the antenna, which is unfavorable, since the resulting design compromise leads to systems of small swath width and low signal-to-noise ratio. The frequency Scan for Time-of-Echo Compression (STEC) technique described in this paper is known from \cite{Roemer18, FScan_PatentUS, Nan2020} and utilizes the available bandwidth to form a narrow frequency-scanning antenna beam illuminating the swath of interest from far to near range. The operation parameters of the technique may be chosen to significantly reduce the pulse echo duration which may be used to significantly increase the transmit pulse duty cycle over what is common for SAR instruments allowing for a lower peak-to-average transmitted power ratio.