A compact single feed dual-band electronically tunable microstrip antenna for operation in GSM/DCS-1800 system is presented. The antenna consists of two resonant elements designed separately and integrated while preserving their designed bands. The two bands are separately tuned using two biasing control circuits. A significant size reduction and bandwidth selection are achieved using a varactor diode as a voltage control capacitance. The design and implementation is carried out on a foam substrate of thickness 2.44 mm and with a dielectric constant 1.2. Simulation and experimental results show that the required bandwidth of the GSM/DCS-1800 system can be easily covered with voltage changes from 1 to 3 V, which is suitable for mobile hand phones.