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The measurement accuracy of an ultra-wideband time domain microwave tomography system is investigated. In order to make an assessment of the random variation of the measurements, the measurement repeatability of the system is evaluated by comparison with an ultra-wideband frequency domain system. A phantom is imaged with the time domain microwave tomography system and the reconstructed images are compared to those obtained by using the frequency domain system. The results suggest that with averaging tens of measurements, the time domain system can achieve the same level of measurement repeatability as that of the frequency domain system in the interesting frequency range of microwave tomography. The imaging results, however, indicate that the phantom reconstruction does not require such high measurement accuracy. The permittivity profile of the phantom reconstructed from the non-averaging time domain measurements is very similar to that obtained by means of the frequency domain system.

In this paper, a time-domain system dedicated to medical diagnostics has been designed, a prototype has been built and its performance has been evaluated. Measurements show that the system has a 3-dB bandwith of about 3.5 GHz and a signal to noise ratio over 40 dB in the frequency range about 800 MHz to 3.8 GHz. The system has been used to perform a microwave tomographic image reconstruction test. The same target was reconstructed based on data measured with a network analyzer.A comparison between the images shows very small differences, and proves the functionality of the time domain system. Index Terms-Microwave imaging, time domain measurements, ultrawideband (UWB).