Dual band microstrip patch antenna element with parasitic for GSM

A dual band microstrip patch antenna element, suitable for GSM 900/1800 base station operation is presented. The geometry consists on a smaller patch inside a larger one. Coupling and separation are provided by a U-slot. A single-layer structure has been designed, fabricated and tested. Good agreement has been obtained between theoretical and experimental results. To provide the required bandwidth for the GSM bands a double-layer structure is under analysis.