A Compact Printed Multi-band Antenna for Laptop Applications

This study proposes a compact printed multi-band antenna, which has the advan- tages of simple structure, small size, easy fabrication, and making integration within thin laptop. The main operating frequencies of the proposed antenna are at GPS (1.575GHz), WLAN (2.4, 5.8GHz), Bluetooth (2.45GHz) and WiMAX (2.5, 3.5, 5.5GHz) bands. The main structure of the antenna is composed of T-shaped monopole and grounded inverted L-shaped branch. The T-shape monopole excites 2.4GHz operating frequency band. And, the grounded inverted L- shaped branch not only can excite 3.5GHz operating band but also can be used for impedance matching, which can tune the bandwidth of each operating band. A branch is added on the left part of T-shaped monopole which can excite GPS band (1.575GHz). Finally, the 5.5GHz operational frequency of WiMAX can be excited by adding a stub on the T-shaped monopole branch. Therefore, a multi-band antenna for laptop applications is achieved. The antenna occupies a small area of 9 £ 47mm 2 only. This antenna is fed on the T-shaped monopole by a 50-› coaxial cable. The measured result shows that the 10dB return loss is satisfled at each operating band, and has a good agreement with simulated result. Moreover, the gain, radiation e-ciency and radiation pattern of each operating center frequency were also simulated and measured. They demonstrate very good performances. The gain is about 1:25 » 6:38dBi and radiation e-ciency ranges from 67% to 95% at each band. The measured radiation pattern is similar to general monopole antenna. The characteristics of the antenna make it attractive for practical application in laptops.