1 RADIATION PERFORMANCES OF A MULTIFREQUENCY DIPOLE ANTENNA ARRAY WITH A LEFT HANDED SUPERSTRATE

Abstract- In this paper, the radiation performances of a multifrequency antenna array (MFAA) which consists of two dipoles (1 and 3) that are radiating at 9.57 GHz and other one (dipole 2) radiating at 11.98 GHz are presented. In order to improve the directivity and to reduce the coupling between the dipoles, a non-uniform Left Handed (LH) superstrate formed by cells of different resonant frequencies has been placed over them. Each dipole is tuned to the resonant frequency of the cells that are on top of it allowing the power transmission and producing a very uniform illumination that enhance the radiation performances of the whole structure. With this configuration, directivity values of 10.1 dB when dipoles 1 and 3 are radiating and 8.1 dB when dipole 2 is radiating have been obtained, with a gap between dipoles of 0.23 λ0 at resonant frequency of the first dipole and a coupling smaller than- 17 dB