Towards Smart Cities: Antenna-Embedded Walls and Antenna-User Interaction Modeling for Enhanced Urban Connectivity

With the rapid evolution of mobile networks and the ongoing deployment of 5G, there is a pressing need for innovative solutions to accommodate the growing number of users and higher data rates facilitated by higher carrier frequency bands. However, as the carrier frequency increases, communication networks face heightened sensitivity to blockages, impeding signal propagation and reducing reliability. This thesis investigates novel electromagnetic modeling techniques of antenna-embedded building walls and antenna-human interaction to enhance 5G and future mobile communication systems, providing tools to develop and test improvements that mitigate their adverse effects on communication quality. The first part of this thesis explores the concept of signal-transmissive walls, where two planar antenna elements are connected back-to-back by a coaxial cable embedded into a load-bearing wall to guide signals from outside into a building. A load-bearing wall, with and without the embedded antenna system, is studied in terms of electromagnetic transmission, thermal insulation, and mechanical stress distribution. Numerical simulations of electromagnetic transmission coefficient, up to 8 GHz, demonstrate that the signal-transmissive wall significantly improves transmission coefficients for carrier frequencies above 2.6 GHz. The full-wave simulation models are later validated by measurements. An analytical electromagnetic transmission model of the wall is developed to optimize signal transmission up to millimeter-wave (mmWave) frequencies, achieving a more than 70 dB improvement over a bare load-bearing wall at 30 GHz. The second part of the thesis focuses on the modeling of antenna-user interactions for mmWave mobile phones. Empirical studies of antenna radiation with a mobile user at mmWave frequencies have largely relied on real humans, lacking repeatability. To address this, a physical human body phantom for mmWave frequencies is presented for the first time, validated by comparing measured spherical coverage of a reference antenna array on a mobile phone-sized chassis against simulations with an accurate numerical human body model. Three different mobile antenna arrays operating at 28 GHz are evaluated using the developed full-body human phantoms to study various antenna array configurations. Finally, photogrammetry is applied to antenna-hand interaction studies for the first time, using 3D hand models of individual users to assess the effects of hand palms and natural grips on the radiation characteristics of 28 GHz mobile phone antennas. The results reveal significant variations in realized gains and radiation efficiency across different user hand models.