Experimental determination and simulations of the Huynen target parameters for full polarimetric millimetre wave concealed weapon recognition

Blackhurst, Eddie, Salmon, Neil and Southgate, Matthew (2018) Experimental determination and simulations of the Huynen target parameters for full polarimetric millimetre wave concealed weapon recognition. In: SPIE Millimetre Wave and Terahertz Sensors and Technology, 10 September 2018 - 13 September 2018, Berlin, Germany.

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Abstract

The Huynen polarisation fork as a representation of the full polarimetric radar signature represents a unique and natural description of a target. This paper investigates the use of full polarimetric radar operating over the band 18-26 GHz to measure the Huynen target parameters of size, orientation, helicity, skip angle and fork angle from a range of canonical polarimetric radar targets and classic concealed weapon surrogates. Measurement will determine how accurately the Huynen target parameters represent the geometries of the canonical targets and surrogate weapons such as concealed metal and ceramic guns, shrapnel and plane sheet dielectrics. Target backgrounds will be large area absorbers and the human body to enable assessment of the capability for stand-off concealed weapons detection. The system used for the measurement comprises a dual channel vector network analyser, a Turnstile orthomode transducer (OMT) and a conical horn antenna. The OMT has an isolation better than -35 dB between orthogonal polarisations. This system measures and calibrates the Sinclair matrices of targets, from which the Huynen target parameters are derived. A simple model of targets based on the original work in Huynen thesis back in 1970 will be presented, enabling comparison between measured and simulated Huynen target parameters to be made. Conclusions are that experimental measurements of the Huynen target parameters of canonical and surrogate targets agree well with the basic theory of the technique and simple model simulations.