Multi-frequency SFCW Radar for Ground Penetrating Radar

摘要

This paper pertains to the design aspects of a multi-frequency SFCW radar with emphasis on the engineering problems involved in its implementation. The dimensioning of the radar is optimised for detection of surface laid and buried landmines with a maximum depth of 50cm and an initial requirement on range resolution of appr. 5 cm. In order to obtain an acceptable data acquisition time, this radar generates 8 separate SFCW signals which are then additively mixed and radiated simultaneously. The target return also comprises the cocktail of returns at these frequencies. The cocktail signal is then split into its constituents and upon completion of the signal collection over 128 frequencies, these are processed collectively to obtain an extremely high resolution synthetic image of the target. The radiated power in each of the 128 frequencies can be chosen independently. The main area of application of this equipment will be in landmine detection. However the potential of the design is multiple: 1. to study waveforms of variable and flexible transmitted power spectra. 2. to study ultra-wide band processing techniques, without the need to have an ultra-wide instantaneous bandwidth. 3. to study coherent, non-coherent and mixed processing concepts. The radar itself will belong to the class of LPI radars in the SFCW mode. The additional advantage here is that this radar can be built using essentially "bought - out" items i.e. it does not require any radically new technology. The paper discusses some of the parameters of the design and the problems involved in the implementation of this radar. It also analyses the ambiguity function of this class of signals and as to how it is affected when the signal processing is carried out in parallel.