This paper presents the design of a triple-band antenna for mobile handset covering frequency bands of GSM 900, GSM 1800, and ISM 2450. The proposed antenna includes two open rings attached with the transmission line and a slotted partial ground plane for the three operating bands. This antenna is printed on a less expensive FR4 substrate, occupying very small volume of 26 × 27 × 1.6 mm3. The ground plane of the proposed structure is extended to meet the dimension of a standard smart mobile phone to verify its applicability as a mobile handset antenna. The results of the proposed triple-band antenna and extended ground plane antenna for the mobile handset are in good agreement. The details of design consideration, working principle and the parametric analysis are discussed. © 2021, Springer Nature Singapore Pte Ltd.