This thesis explores the use of complementary asymmetric split ring (CASR) unit cell (Ucell) with modified edge at its longest arm (anisotropic) as a novel metasurface which can produce stable EBg region and demonstrate its versatility as a novel surface waveguide and as a lens to improve an antenna efficiency. Major setback within this field is, no proper method to characterized unit cell EBg and ways to mitigate complex structural approach to develop unit cell based EBg. Additionally, scalar version of non optimized unit cell as metasurface that are independent on the polarization and wave vector of electromagnetic radiation that interacts with its surface. Lastly, scalar metasurface cannot mitigate unwanted surface wave. This research scope will investigate ways to justify CASR unit cell, the effect of introducing a triangular-tip-edge (TrTE) and tapered tip edge (TaTE) onto the split gap of a dual circular split ring unit cell in comparison to the conventional CASR in terms of scattering parameters, impedance, unit cell formation in multiple formation and its effect towards the electric field, and magnetic field. EBg region achieved was 5.9265 to 5.9516 GHz (25.1 MHz) for CASR, for CASR TrTE, 6.0214 to 6.0378 GHz (16.4 MHz) and CASR-TaTE 5.8424 to 5.9378 GHz (95.4 MHz). 3D tetrahedral meshing frequency eigenmode solver and interpolated quasi newton finite integration optimization algorithm within the Finite Integration Technique (FIT) were utilized in comparing proposed unit cells to the result of a conventional CASR unit cell. Method used to conduct the research was validated using calibrated equipment and measured results. This thesis have successfully showcased three (3) different passive metasurface using modified CASR unit cell. Firstly, a CASR based surface waveguide, 13.5 to 21.7 V/m at 900 and another similar iteration of CASR surface wave guide with smaller CASR in between, 55 to 60 V/m at 900 was achieved. Second, CASR based surface beamwave director, based v-shaped formation. Behavior of modified CASR Ucell with desired EBg are found suitable to separate a beam wave into two direction. By reshaping the CASR longest arm edge to a triangular tip, a good and stable bandgap region exists from 6.0214 GHz to 6.0378 GHz The approach of this integration can be used to design better EM shielding area and minimized interference especially for flat surfaces. Findings shows that, based on bare meal laminate, 83.3 V/m at 900 was produced. When compared to the v-shaped based CASR formation, for 1 layer the readings was 71.2 V/m log, at 2 layers was 35.4 V/m log and at 3 layers was 24.52 V/m. Third, CASR based surface radiation director based on the unit cell arrangement and position. Behaviour of the incident wave was first investigated using a bare flat metal laminate (381 V/m source from the edge and 440 V/m source from above patterned laminate) and then compared with a modified tip of CASR surface. Comparison made between simulation and measured samples working at 5.8 GHz, indicates that. EM flow can be altered to desired angle, split into two direction or multiple direction if the source position is made known. For signal source coming the side edge, 156 V/m (energy converge into two direction, 900 and -900), 496 V/m (split into six angles). For signal source coming from above the patterned laminate, 418 V/m (energy converge into two direction, 600 and -600), and 452 V/m (700, 900, 1100), which depends closely on the CASR formation. By using the same CASR surface, if a known EM source is placed at the center, it is found that CASR perform better as a reflector compared to a flat metal surface. This approach can be used to help improve microwave design and enhance specific communication isolation. Achievements in part two and three were combined to create a novel lens that can improve efficiency of an antenna from 26.5 % to 40.6 %. CASR and grew its bandwidth from 0.1039 to 0.1946 GHz. CASR Ucell have proven to be useful in enlarging desired EBg region center operating frequency, redirect radiation pattern and improve scattering parameter response.
