A compact internal tri-band antenna for mobile handsets

A compact and low profile internal antenna capable of operating in multiple bands is proposed. It consists of a long monopole ring, which is top-loaded by a helical element in order to produce two main resonances of wide bandwidth. Its compact size of length 10 mm, width 28 mm and height of 6 mm and small volume of 1.68 cm/sup 3/, makes it possible to be used internally, inside the mobile phone. With the help of a small matching circuit a VSWR < 3 is achieved covering the bands of GSM900 (880-960 MHz), DCS (1710-1880 MHz) and PCS (1850-1990 MHz). The efficiency is above 50% in all bands. The specific absorption rate (SAR) is also measured, presented and discussed in this paper.