A novel design technique for control of defect frequencies of an electromagnetic bandgap (EBG) superstrate for dual‐band directivity enhancement

Abstract In this paper, we propose a novel design technique to control the defect frequencies of an electromagnetic bandgap (EBG) superstrate with the objective of enhancing the directivity of a patch antenna at two frequencies. Two different defect configurations, the first of which is introduced by the ground plane of the antenna while the other is produced by a row of rods with dissimilar dielectric constants in the EBG structure, are examined in detail in order to achieve dual‐band operation. We begin by investigating the EBG structure and varying several of its parameters to determine the locations of the bandgap and defect frequencies, as well as their controllability. Finally, the promising designs for the EBG superstrates, which provide enhanced directivities for the EBG antenna, are evaluated to validate the proposed design scheme. It is demonstrated that the directivity of the antenna with a 12 × 3 EBG superstrate increases to 18 and 18.5 dBi, respectively, at the two design frequency bands, as compared to that of the antenna alone (maximum 10 dBi) without the superstrate. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 25–31, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20196