In the realm of metamaterials and electromagnetic engineering, a metasurface is a two-dimensional array of subwavelength-scale structures meticulously engineered to manipulate electromagnetic waves. Unlike conventional bulky optical elements, metasurfaces represent a novel approach, providing ultra-compact, planar solutions capable of controlling the wave's phase, amplitude, and polarization across a broad spectrum. This transformative technology finds multifaceted applications, spanning from high-efficiency optical devices and advanced imaging systems to next-generation communication systems and sensing platforms.Within the context of this dissertation, I delve into four different designs and applications of metasurface research, each poised to push the boundaries of electromagnetic engineering. These include a metascreen, two antennas, and a time-varying capacitor, each contributing to the evolving landscape of metasurface technologies.One of the pivotal contributions explored in this research is the development of a dual-polarization metascreen. This innovation holds significant importance in the realm of electromagnetic engineering and communication systems. A dual-polarization metascreen, capable of manipulating both horizontal and vertical polarizations of electromagnetic waves simultaneously, unlocks a range of practical advantages. Firstly, it enables versatile control over the polarization state of transmitted or received signals, making it invaluable for applications such as radar systems, where the ability to switch between polarizations rapidly can enhance target detection and tracking. Moreover, in wireless communication, dual-polarization metascreens offer increased spectral efficiency by accommodating multiple data streams through polarization multiplexing. This results in improved data rates and network capacity. Additionally, these metascreens find applications in satellite communication and remote sensing, where the capability to simultaneously capture diverse polarizations enhances data acquisition and accuracy. In essence, the development and implementation of dual-polarization metascreens pave the way for advanced and versatile electromagnetic systems with enhanced performance and capabilities.Building upon the breakthrough of dual-polarization metascreens, the subsequent chapter in this dissertation embarks on the exploration of a dual-layered, Ka and W band sinusoidally modulated antenna. These frequency bands, while individually vital, have never been addressed together in a single antenna design. This novel approach ventures into uncharted territory, as the integration of dual-band functionality across these relatively far-apart frequencies presents unique challenges and opportunities. This research breaks new ground by delving into the intricate design, characterization, and implementation of such dual-band metasurface antennas, making significant contributions to the advancement of connectivity technology and broader applications in radar systems, remote sensing, and millimeter-wave technologies. The exploration of this territory not only expands the boundaries of electromagnetic engineering but also holds the promise of unlocking new capabilities for advanced communication and sensing systems, thereby solidifying the progressive trajectory of metasurface technologies in the field.Furthermore, another sinusoidally modulated antenna examined within this dissertation provides valuable insights into the calculation of dispersion characteristics for a 3D printable antenna. The rapid calculation of dispersion curves and the swift fabrication of antennas through 3D printing are pivotal advancements in the field of electromagnetic engineering. Calculating dispersion curves efficiently allows for comprehensive characterization of the propagation properties of electromagnetic waves within various materials and structures. Conversely, 3D printing offers a fast and cost-effective method for prototyping and manufacturing antennas with intricate geometries and tailored properties. This rapid turnaround time accelerates the research and development process, fostering innovation and enabling the swift deployment of custom-designed antennas for emerging technologies. Together, the expedited dispersion curve calculations and 3D printing capabilities seamlessly streamline the antenna design process, thereby propelling advancements in communication, sensing, and connectivity technologies. This approach to antenna research underscores the interdisciplinary nature of this dissertation and its significant contributions to the evolving field of electromagnetic engineering.As we delve further into the realms of electromagnetics and photonics research, one of the forefront areas involves the study of structures with time-varying parameters, such as permittivity and permeability. This exploration of time as a new degree of freedom for controlling electromagnetic waves has yielded structures with fascinating functionalities, including time-Floquet topological insulators, temporal-based non-reciprocity, and static-to-dynamic field conversion. These innovations have addressed challenges faced by time-invariant structures, promising new avenues for wave-matter interactions. Recently, the fusion of time-varying media with the concept of metamaterials has opened another intriguing pathway to control and achieve desired functionalities in electromagnetic systems. This work, however, focuses on a specific subset of time-varying media, namely time-varying networks composed of lumped elements like resistors, capacitors, and inductors with time-dependent properties. These networks offer an accessible platform for experimental demonstrations and have sparked significant research interest. While previous studies predominantly explored periodically modulated lumped elements, this work introduces a novel approach employing aperiodic time modulation of a single capacitor to capture the energy of arbitrary pulses. This advancement addresses practical challenges and significantly expands the potential applications of time-varying lumped elements in electromagnetic energy accumulation, highlighting the interdisciplinary and innovative spirit that drives research in this field.In summary, this dissertation represents a comprehensive exploration of diverse aspects within the field of electromagnetic engineering and photonics. From the development of advanced metasurface technologies and their applications in communication and sensing systems to the utilization of time-varying media for innovative energy accumulation techniques, this research underscores the multifaceted nature of contemporary electromagnetics and photonics. Through theoretical analysis and innovative design, this work not only contributes to the academic understanding of these fields but also holds the potential to catalyze technological advancements with far-reaching implications.