Printed double S-shaped monopole antenna for wideband and multiband operation of wireless communications

A novel and simple printed wideband and multiband monopole antenna is presented. Printed on a single dielectric substrate and easily fed by using a 50 Ω microstrip line, a low-profile antenna structure with two parallel S-shaped meandered lines of different sizes, capable of generating a number of separate resonant modes for multiband operations, is achieved. By introducing a protrudent strip to a two-arm S-like monopole antenna, much wider impedance matching concealing multi-frequency resonant modes at the higher band can be produced. From fabricating and measuring the prototypes of the proposed antenna, two available bands with 10 dB return loss bandwidths of about 85 MHz at 2.44 GHz band and of about 73.5% ranging from 4.14 GHz to 8.95 GHz were obtained. A stably omnidirectional radiation pattern and an average gain of greater than 5 dBi over the main operating bands were also obtained.