Quad-band Antenna for a Foldable Mobile Phone

In this paper a novel antenna is shown, which uses a combination of helical and monopole elements in order to produce, with the help of a matching circuit, two very wide in bandwidth frequency responses, achieving the coverage of four mobile phone frequency bands, GSM850 (824-894 MHz), E-GSM (880-960 MHz), DCS (1710-1880 MHz), PCS (1850-1990 MHz). Due to its novel design, this antenna has a small size resulting to a compact volume, making it possible to be used inside a mobile phone thus making it invisible to the user. Various simulations and measurements are shown, when the antenna is placed on the bottom side of a 'clamshell' type mobile phone, achieving a voltage standing wave ratio (VSWR) of less than 3 and a radiation efficiency of more than 50%, across all frequency bands