Time-Domain System for Millimeter-Wave Material Characterization

Time-domain material characterization using a leaky lens antenna and an in-house fabricated millimeter-wave wavelet generator using III-V technology is investigated. The wavelet generator produces short high-frequency pulses and is connected to a wideband and nondispersive leaky lens antenna. A purely time-domain methodology is used to extract the complex permittivity of nondispersive and nonmagnetic materials. The permittivity is found from the phase delay and the amplitude mismatch introduced by the object at the carrier frequency of the pulse. The wide bandwidth of the wavelet is used to investigate frequency-dependent material properties. Measurement results from two dielectric slabs are illustrated. The time-domain methodology is verified by frequency-domain measurements and analysis.