This paper introduces a silicon-based imaging array for remote measurements of complex permittivity of tissue. Using a coherent pulsed measurement approach, this time-frequency resolved technique recovers the three dimensional mapping of electrical properties of the subject in the microwave/millimeter-wave frequency spectrum. Some of the major challenges in the design of the system are described. Initial measurement results from the prototype high-resolution transmitter fabricated in a 0.13 μm SiGe process are described. The transmitter achieves pulse widths suitable for millimeter-level accuracy imaging.