Novel smart antenna array for IEEE 802.11a wireless LAN applications

A 3×3 phased-array antenna of rectangular patches is designed for WLAN applications in the 5.25 GHz band. The elements are probe-fed so that they can be fed through separate phase shifters or switches. Suggestions have been made to reduce the number of phase shifters. The phased array scans the space through a switched-beam algorithm, finding and focusing on the desired signal´s direction of arrival. The main advantage of the design is that it is applicable as an external module, regardless of the other parts of the system, i.e. the WLAN card. The performance of the smart antenna is simulated and compared in terms of gain and SIR with the performance of a single patch antenna. In all simulations, exact element patterns and mutual coupling effects are taken into account. In an interference-free environment a minimum 25 dB gain improvement is achieved. Environments with one and two interfering signals show at least 4 dB and 7 dB SIR improvement respectively.