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In the framework of non-destructive testing and imaging, ultrasound tomography can have an important role in several applications, especially in the biomedical field. The motivation beyond the use of this imaging technique lies in the possibility of obtaining quantitative imaging which is also operator-independent, conversely to conventional approaches. Thus, the need for public data sets for testing inverse scattering approaches is always persisting. To this aim, this paper introduces an experimental multiple-input-multiple-output ultrasound tomographic database whose acquisitions were performed by an air-matched in-house system designed and built by the Authors. The proposed database provides several cases with single and multiple objects of different shapes, sizes, and materials, to be imaged in laboratory-controlled conditions. Therefore, these scenarios can represent interesting options for the preliminary testing of tomographic ultrasound imaging approaches.

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In this paper we show a procedure to measure the impedance mismatch of antennas by exploiting the Time Domain (TD) option available in usual VNAs. The procedure can be applied even in the presence of reflecting obstacles in the measurement scenario surrounding the antenna under test (AUT). It is shown that effective application of the procedure requires to fulfill a reduced number of constraints basically involving the distance of the AUT from the nearest obstacle, the response resolution to be set through the TD option of the VNA, and the length of the gating aperture to be applied to the received signal. The proposed measurement procedure is in principle applicable to any antenna. However, it is very easy and advantageous for antennas having short responses in the time domain, such as horn antennas, where the method can likely be applied to frequencies less than 500 MHz. Comparison between the results obtained from measurements performed inside an anechoic chamber (that is, in the absence of reflecting obstacles around the AUT), outside the anechoic chamber, and even inside a reverberation chamber, demonstrate the effectiveness of the proposed measurement procedure.