Analysis and Design of Wideband Planar Yagi- and Bi-yagi Arrays with Photonic Band Gap

In this work, the analysis and design of wideband microstrip yagi and bi-yagi antenna arrays with photonic band gap (PBG) is presented. By using the bi-yagi planar array, a high directive gain and a high front-to-back ratio are achieved in comparison with that of the single microstrip yagi structure. The current distribution, return loss, radiation pattern, and input impedance are calculated. For a single yagi, wide bandwidth up to 12.81% at 10.15GHz is obtained. However, a high directive gain is achieved with the bi-yagi. The PBG structures force the antennas to have stop band at the higher end of the operating band. In addition, it increases the front-to back (F/B) ratio. The finite difference time domain (FDTD) with the perfect matched (PML) and a numerical package based on the method of moment (MOM) are used in the present analysis and design. A closed form based on an approximate equivalent circuit is used to get approximate dimensions of the PBG structures.