Triple-band planar dipole antenna for omnidirectional radiation

This letter presents a compact triple-band dipole antenna that radiates omnidirectionally. The antenna is a T-shaped structure that is excited through a vertical feedline. Located under the horizontal rectangular patch are two /2 long meander-line stubs symmetrically interfaced to the feedline. On the bottom side of the substrate is a trident shaped ground-plane structure located under the T-shaped radiator. The proposed configuration is essentially composed of three radiating elements, which has a small footprint of 19x16mm(2) on a 0.8mm thick substrate. Regions of enhanced impedance matching are realized between 0.5 and 2.69GHz, 3.2-4.44GHz and 4.82-6.6GHz covering major portions of L, S, and C-bands. It is shown by reducing the gap between the meander lines stub and rectangular patch reduces results in increased gain performance. Measured results confirm the antenna exhibits omnidirectional radiation with enhanced impedance match at 1.5, 4, and 5.4GHz with corresponding average gain of 1.6dBi, 3.4dBi, and 3dBi, respectively.