Theoretical Modelling on Substrate Integrated Impedance Surfaces Incorporated on Leaky Wave Antenna

The operating frequency of electromagnetic devices, such as waveguides, cavities, resonators, and antennas, is generally determined by their physical dimensions. The purpose of this thesis is to propose a new concept of substrate-integrated impedance surface (SIIS), which is intended to enable the arbitrary control of the dimensions and operating cutoff frequency of electromagnetic waveguides, resonators, and antennas. In this study, we validate the effectiveness of loading a substrate-integrated waveguide (SIW) with a capacitive SIIS (e.g., a blind-via array) to reduce its cutoff frequency. As a result, SIIS techniques may be useful in miniaturizing SIW-based components that operate at low frequencies. We adapt the non-local homogenization theory to build a solid approximation expression and derive an analytical model to assess and extract the surface capacitance of SIISs of different geometries using stochastic gradient descent (SGD) followed by the least square error (LSE) method to solve non-linear regression problems and fit exponential curves. To prove the concept, we conducted several experiments with SIIS-loaded SIWs set with different parameters to extract surface capacitance. As a result, we observe that the analytical and numerical results are in good agreement. Finally, we demonstrate that the capacitive SIIS incorporated with a half-mode substrate integrated waveguide (HMSIW) reconfigured as leaky wave antenna (LWA) expressed as HMSIW-LWA has the possibility to reconfigure and steer the radiation patterns. With the greatest hope, the research project findings may be of interest given the increasing importance of 5G millimeter-wave products and microwave quantum systems.