Development of a directional dual-band planar antenna for wireless applications

A new type of directional dual-band antenna is developed for 2.4/5 GHz wireless applications. The dual-band antenna consists of a longer dipole for the lower band and a pair of shorter dipoles for the upper band. A simple coupling microstrip line is employed to excite the dipoles. Both the dual-band antenna and the feeding microstrip line are printed on the same substrate, leading to a fully planar structure. The dual-band planar antenna achieves a desirable directional radiation pattern with an antenna gain of near 8 dBi for the lower band and 9-10 dBi for the upper band. A comprehensive analysis and design for the development of the directional dual-band antenna is presented.