Compact circularly polarized omnidirectional microstrip antenna

A new type of circularly polarized omnidirectional microstrip antenna employing zeroth-order resonator loaded with stabs along the ground perimeter is presented. The proposed antenna has the conceptual configuration of the horizontal magnetic and electric loop currents which act as the electric and magnetic monopole antennas, respectively. By adjusting the relevant dimensions of the loaded stabs, circularly polarized omnidirectional operation can be realized. The proposed antenna operates at 1.55 GHz and provides a 10 dB input return loss bandwidth of 1.3%. The whole dimensions of the proposed antenna are about lambda/6 X lambda/6 X lambda/96 in terms of vacuum wavelength. The simulated and measured radiation patterns show the proposed antenna radiates electromagnetic wave omnidirectionally. The simulated axial ratio of the proposed antenna indicates it has good circular polarization performance. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2643-2646, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24697