|dc.description.abstract||The target of this study is to develop a smart antenna array for mobile communication application, so as to improve the transmission efficiency and interference suppression. The center frequency of 2.4 GHz is chosen, which is one of the ISM band (Industrial Scientific Medical Band) and is commonly used for WLAN (IEEE 802.11b / IEEE 802.11g), Bluetooth, and ZigBee applications.
Most of the conventional antenna designs for mobile application are omnidirectional ones because the signal may come from any direction. However, this does not lead to optimal data transmission performance and the antenna will also receive interferences from all directions. Since the wanted signal comes from a particular direction only, we propose an antenna array for mobile devices, in which the relative phases of the antenna elements are varied in a way that the main beam of the radiation pattern can be set to the desired direction with suppression of undesired interferences from other directions.
This work employs a 2×2 patch antenna planar array on a PCB (printed circuit board) size of 200 mm ×137.5 mm, which is about the size of a 7.9 inch tablet. The relative phase of the antenna feed is controlled by digital phase shifters. The main beam of proposed antenna array can be set to four directions, which are the east, west, south, and north sides. The measured bandwidth for 10 dB return loss is about 4.6%, with a peak gain of 1 dBi and a HPBW (half-power beam width) of about 50 degree. It can be applied to the back of tablet of size larger than 7.9 inch for improving the transmission efficiency and interference suppression.