Miniaturization of microstrip patch antenna for wireless applications by use of multilayered electromagnetic band gap substrate

The effect of a two-layer, periodic, electromagnetic bandgap (EBG) substrate on the performance of a dual-polarization, square, patch antenna is investigated in this paper. The antenna is printed in a gap area of the uppermost surface of the EBG substrate, disturbing by its presence the periodicity and the symmetry of that surface. Finite difference, time domain methods have been used for the simulations and a prototype of the proposed structure has been made in our laboratory in order to verify the simulated results. The proposed antenna resonates at 2415MHz and it is 24% smaller in area than a square patch with the same type of feedlines and the very same resonance frequency, which is printed on an ordinary, reference substrate. By ¿ordinary¿ it is implied that the reference substrate is a stack of two layers having the same dielectric constant and thickness as those of the proposed two-layer, EBG substrate. The decrease in frequency is 45.2% with respect to a square patch of the same size on the reference substrate. Still, the bandwidth of the proposed antenna increases by 12%, despite the narrowband nature of the quarter-wavelength matching circuits at both inputs, and it presents higher isolation between the two ports.