A dual-band antenna for cellular applications

The author presents a dual-band antenna design for GSM (900 MHz) and DCS (1800 MHz) cellular radio bands. Simulation results show that the input impedances at the center of both bands are about 50 ohms. Therefore, an additional matching network is not necessary. This means there is no efficiency loss due to adding matching networks. The radiation patterns are basically omnidirectional. Although the GSM and DCS bands are used here, similar results can be obtained for the 900 MHz and 2.4 GHz ISM bands. Furthermore, the design ideas presented can be used for tri-band applications.