Design of metamaterial superstrates and substrates for directivity and port isolation enhancement of a dual-frequency dual-polarization microstrip antenna

Abstract

In this paper, we propose a novel design for enhancing the directivity and port isolation of a dual-frequency dual-polarization (DFDP) microstrip antenna by using metamaterial superstrates and substrates. To enhance the directivity of this without a complex feed network, we first design a strip-mesh type of Frequency Selective Surface (FSS) type superstrate as a cover for a DFDP antenna, which supports two orthogonal polarizations at two different resonant frequencies. Next, a 2D anisotropic uniplanar compact bandgap ope ground plane is introduced to enhance the isolation between the two ports of the DFDP antenna. It is demonstrated that the directivity at two frequency hands is enhanced by about 13 dB in the first band and by similar to 12 dB at the second one, when compared with the patch antenna alone. Also, the isolation between the two ports is shown to be -35 dB, which is - 15 dB lower than that of a conventional patch antenna. (C) 2006 Wiley Periodicals. Inc.