Stepped-frequency software-defined ground-based synthetic aperture radar

This paper presents a practical implementation of a software-defined ground-based synthetic aperture radar. The proposed system uses a PC, a general purpose low-cost SDR platform and a minimum number of external components. The SDR platform is a USRP N200 equipped with a WBX RF daughterboard. The only external components are two offthe- shelf RF switches, an Arduino Uno microcontroller board, a fixed RF attenuator and two Vivaldi antennas. The system implements stepped-frequency radar operation with a bandwidth of 1500 MHz (500 – 2000 MHz) achieving a resolution of 10 cm in air. The proposed system mimics the behavior of Vector Network Analyzers. It works by sweeping its operating frequency over the 1500 MHz frequency band and storing the amplitudes and phases of the scattered waves. These are assembled in a matrix, the so-called raw data matrix, which is processed using an implementation of the backprojection (BP) SAR algorithm to generate the bidimensional focused image. All of the above-mentioned assertions have been validated experimentally, proving the proposed system’s ability to generate high resolution images of the analyzed scene.