Printed Monopole Diversity Antenna for USB Dongle Applications

A compact printed multiple-input multiple-output antenna is presented for USB dongle application which covers the WLAN (2.4-2.48 GHz), WiMAX (3.4-3.8 GHz), and HiperLAN (4.7-5.83 GHz) bands. The two monopoles are closely spaced on the PCB at distance of about 0: 094 lambda(0) at lowest resonant frequency. To reduce the mutual coupling between the ports as well as to get the desired operating bands, combination of X-shaped neutralization line and L-shaped slots [defected ground structure (DGS)] are used. Due to which aimed frequency bands as well as better than -14 dB isolation are achieved. The mechanism of neutralization line and DGS are analysed based on the S-parameters and surface current distributions. An equivalent circuit model is also used to understand the mechanism of the neutralization line alone. The envelope correlation coefficient and ratio of mean effective gain are calculated which are found to be well below 0.4 and close to unity, respectively.