Design And Implementation Of WLAN Antennas

WLAN (Wireless Local Area Network) technology combines the computer network with the wireless communication system. With the rapid development of the wireless communication technology, WLAN is used more and more widely. Antenna is an important part of WLAN system. Thus design of WLAN antennas meeting various WLAN criterion requirements is very urgent, and will be of practical significance.In this dissertation, firstly two dual-band compact WLAN antennas have been proposed. By notching slots on the ground plane, the first antenna can generate two separate impedance bandwidths, 2.3 to 2.5 GHz and 4.9 to 6 GHz. By gradually changing the patch, the second antenna has a compact configuration, which covers the 2.4/5.2/5.8 GHz WLAN operating bands. Prototypes of these two WLAN antennas have been manufactured. Measured results show that both antennas satisfy the impedance band requirements and have good radiation characteristics.Secondly, a printed monopole antenna has been proposed,based on the special requirements of USB-WLAN cards. Fed by the microstrip line, the proposed antenna has a similar dimension with normal USB flash disk, and can be integrated with WLAN card easily. Its resonant frequency is located at about 2.4 GHz with a good impedance bandwidth. Moreover, good radiation characteristics have been achieved. The antenna is suitable for applying in the WLAN terminal unit.Finally, we propose a frequency reconfigurable antenna. By switching on or off two embedded switches in the proposed antenna, four operating states have been realized. As one of the states, when both switches are closed, the antenna operates at a single band with resonant frequency located at about 2.4 GHz and -10 dB impedance bandwidth from 2.2 to 2.65 GHz. In addition, when the switch states change, the operating frequency of the antenna will change again.