Closely coupled metallodielectric electromagnetic band-gap structures formed by double-layer dipole and tripole arrays

The concept of closely coupled metallodielectric electromagnetic band-gap (CCMEBG) structures is introduced and investigated using two-dimensional (2-D) double-layer dipole and tripole arrays. An efficient numerical method based on a set of coupled integral equations is used to simulate the double-layer array response. The arrays are placed in close proximity to each other and shifted appropriately in order to produce maximum element coupling. Measurements are presented for oblique plane wave and surface wave incidences. A substantial decrease of the stopband center frequency is observed with the CCMEBG design for both element geometries. Furthermore, wider bandwidth and improved angular stability as compared to single-layer MEBG is obtained. The tripole arrays arranged on a hexagonal lattice exhibit common stopband for any polarization of the incident field due to the symmetry of the element in conjunction with the lattice. The lowering of the resonance for up to 4 to 1 in simulation results emerges as the layers are separated by less than λ/1200 (0.1 mm at 2.5 GHz).