Achieving a Continuous Duty Cycle with the f-STEC Imaging Mode

In conventional pulsed Synthetic Aperture Radar (SAR) instruments, the echo is received in the time between the short transmit pulses. Due to the way the swath is imaged, the echo is proportional to the scene size and long in comparison to the duration of the transmitted pulse, limiting the pulse duty cycle of the instrument. The Frequency Scan for Time-of-Echo Compression (f-STEC) imaging mode scans the swath with a narrow beam from far to near range, drastically reducing the echo duration and allowing for higher pulse duty cycles up to 70-80%. From a technological point of view, achieving a pulse duty cycle of 100% is advantageous in multiple ways: it further reduces the peak-to-average-power ratio and also enables the use of already existing technology from the telecommunication sector for realizing such a system. This paper presents a technique that achieves a continuous pulse duty cycle with the f-STEC imaging mode, by exploiting the characteristics of the f-STEC echo and carefully selecting the parameters of the SAR instrument. The proposed technique works without adding complexity to the system and furthermore, increases the pulse repetition frequency, lowering the minimum antenna length requirement of f-STEC SAR instruments.