Spectral coding is of special interest in high-sensing-capacity imaging applications. This letter presents the design, fabrication, and experimental validation of a lightweight and robust 3-D-printed compressive horn antenna, capable of performing spectral coding for such applications. First, a pyramidal horn antenna is designed to operate within the E-band. Then, a dielectric piece with a pseudorandom geometric pattern is inserted inside the horn to distort the radiation pattern of the antenna in both near- and far-field regions. The performance of both antennas is evaluated by their return loss and radiation patterns.

Digital Breast Tomosynthesis (DBT) can be fused with microwave Nearfield Radar Imaging (NRI) in order to improve breast cancer detection. This paper presents the design of a new miniaturized ultra-wideband Antipodal Vivaldi Antenna (AVA), which can be used in such a hybrid DBT/NRI mechatronic imaging device. The antenna is miniaturized by using a coupling media and a substrate that have a high effective dielectric constant. Preliminary results show that the designed antenna has a return loss above 9 dB in a 2.5 GHz frequency band.

The use of solid cavities around electromagnetic sources has been recently reported as a mechanism to provide enhanced images at microwave frequencies. These cavities are used as measurement randomizers; and they compress the wave fields at the physical layer. As a result of this compression, the amount of information collected by the sensing array through the different excited modes inside the resonant cavity is increased when compared to that obtained by no-cavity approaches. In this work, a two-dimensional cavity, having multiple openings, is used to perform such a compression for ultrasound imaging. Moreover, compressive sensing techniques are used for sparse signal retrieval with a limited number of operating transceivers. As a proof-of-concept of this theoretical investigation, two point-like targets located in a uniform background medium are imaged in the presence and the absence of the cavity. In addition, an analysis of the sensing capacity and the shape of the point spread function is also carried out for the aforementioned cases. The cavity is designed to have the maximum sensing capacity given different materials and opening sizes. It is demonstrated that the use of a cavity, whether it is made of plastic or metal, can significantly enhance the sensing capacity and the point spread function of a focused beam. The imaging performance is also improved in terms cross-range resolution when compared to the no-cavity case.

Currently X-ray-based imaging systems suffer from low contrast between malignant and healthy fibrous tissues in breast. Microwave Near-field Radar Imaging (NRI) shows a higher contrast between the aforementioned tissues and therefore can enhance tumor detection and diagnosis accuracy. In this work, we present the first imaging results of our developed NRI system that is equipped with a pair of Antipodal Vivaldi Antennas. We used a metal bearing ball immersed in oil as our object of interest, to keep the first measurement configuration simple. Moreover, to demonstrate the safety of our system for human subject tests, we simulated the Specific Absorption Rate (SAR) in a realistic breast tissue model and compared the resulted values with both the USA and Europe standards. The results show that firstly the imaging results from the measurements and simulations are comparable, and secondly the antennas radiations meet the SAR criteria.