Metamaterial inspired, electrically small, GSM antenna with steerable radiation patterns and high radiation efficiency

Abstract

In this study, metamaterial inspired, electrically small, single band antennas with steerable radiation patterns and high radiation efficiencies are proposed. Three different antenna structures having their maximum directivities in the vertical (Antenna A), diagonal (Antenna B) and horizontal (Antenna C) directions are presented and their simulated performance characteristics are reported. These antennas, which consist of a coax-fed printed monopole and a capacitively loaded loop (CLL) as a near-field resonant parasitic element, radiate as magnetic dipoles at each of their resonance frequencies, which are defined mainly by the size of the CLL element and its gap. The direction of the maximum radiation is controlled by the position of the monopole and the CLL gap. These antennas are designed to operate at the GSM frequencies (1.93-1.99GHz). For each of these antenna designs, ka is smaller than 0.58 at its operating frequency. The radiation efficiencies of Antenna A, B and C are equal to 0.89, 0.91 and 0.81 respectively.