ABSTRACT
The proposed planar EBG unit cell is shown in Figure 2.1. The size of the unit cell is 4.32 mm × 4.32 mm. A metal pattern is etched on top of a conductor backed GML 1000 substrate, with relative permittivity εr = 3.2 and thickness h = 0.762 mm. The metal pattern can be seen in black in Figure 2.1. This metal pattern is formed by appropriately modifying the conventional uniplanar EBG structure reported in References 13 and 14. For comparison, a conventional uniplanar EBG with the same substrate parameters as those of the proposed EBG structure is considered. Its dimensions are shown in Figure 2.2. In the proposed structure, the meander lines from the center of the structure to its four corners provide the inductance, and the capacitance is provided by the interdigital lines on the periphery of the unit cell. Comparing the proposed and conventional EBG structures with the same overall size (4.32 mm × 4.32 mm) in Figures 2.1 and 2.2 reveals that the length of the lines providing inductance and the length of the gap providing capacitance in the proposed structure are greater than those that exist in the conventional structure, resulting in higher overall inductance and capacitance. Thus, the resonance frequency shifts downward, making the proposed structure more miniaturized than the conventional structure.
