Compact Dual-Band WLAN Diversity Antennas on USB Dongle Platform

An antenna system comprising two closely spaced chip antennas is proposed for dual-band wireless LAN uses. The distance between two chips is 12 mm and the spacing between antenna feeds is 1 mm only. Yet, superior isolation performance is achieved in both operation bands. A novel isolation enhancing measure is implemented for the higher 5 GHz band, which is done by adding a pair of open-ended stubs next to antenna feeds. The stub pair functions as an all-stop filter and elevates the port isolation. Rigorous simulation works were conducted to associate antenna geometry with performance features. Results such as impedance matching, isolation, and radiation patterns were examined jointly to identify mechanisms of its decoupling and diversity features. Antenna diversity assessment measures including the envelope correlation coefficient and the effective diversity gain were derived. Results demonstrate that the proposed compact two-antenna configuration suits well to the diversity antenna need on portable devices.