Loaded waveguide measurements of plastic explosives at V-band

Abstract

Dielectric measurements of plastic explosives using a loaded waveguide technique via vector network analyzer and banded MMW extender modules operating at V-band (50 – 75 GHz) are performed. A portion of explosive sample is inserted into a waveguide shim 2mm in length and trimmed flush with the faces of the shim. Two-port S-parameter measurements were conducted on the explosive; the empty shim is similarly characterized. Using standard waveguide equations and the measured length of the shim, the complex S-parameter data obtained with the filled shim is optimized to four free parameters — complex permittivity and distance offsets for the two sample faces relative to the calibration planes. Permittivity data obtained from measurements of the plastic explosives C-4, Primasheet 1000, Primasheet 2000 and Semtex 10 are presented. Results obtained for C-4 are comparable to other data in open literature. Excellent agreement between the experiment and the fit is obtained using a constant permittivity across the waveguide band, indicating that dispersion is not significant for these materials.