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Accurate human identification using radar has a variety of potential applications, such as surveillance, access control and security checkpoints. Nevertheless, radar-based human identification has been limited to a few motion-based biometrics that are solely reliant on micro-Doppler signatures. This paper proposes for the first time the use of combined radar-based heart sound and gait signals as biometrics for human identification. The proposed methodology starts by converting the extracted biometric signatures collected from 18 subjects to images, and then an image augmentation technique is applied and the deep transfer learning is used to classify each subject. A validation accuracy of 58.7% and 96% is reported for the heart sound and gait biometrics, respectively. Next, the identification results of the two biometrics are combined using the joint probability mass function (PMF) method to report a 98% identification accuracy. To the best of our knowledge, this is the highest reported in the literature to date. Lastly, the trained networks are tested in an actual scenario while being used in an office access control platform to identify different human subjects. We report an accuracy of 76.25%.

Currently, no publicly available comprehensive set of specifications exists for the design of ground‐penetrating radar antennas. Specifications are presented and derived for the design of a ground‐penetrating radar antenna based on the antenna's interaction with the rest of the radar system. Typically, ground‐penetrating radar antenna engineers are given basic parameters such as gain and bandwidth to design an antenna. An antenna can be designed to meet those specifications but may not perform well in a ground‐penetrating radar imaging system. By considering the whole system, including the operation parameters, expected targets, and signal processing algorithms, we can constrain the less‐commonly considered performance aspects of an antenna to perform more reliably in a deployment. We propose quantitative specifications for the antenna's coupling, beamwidth, boresight radar cross‐section, pulse integrity, residual ringing, and front‐to‐back ratio. Meeting these antenna specifications will decrease the probability that a deficiency in the antenna design impacts the radar's image output. Finally, a summarised design equation table that will be helpful in the ground‐penetrating radar antenna community at large is offered.

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