Reasearch On WLAN Base Station Antenna

WLAN(Wireless Local Area Network) technology combines the computer networkwith the wireless communication system. WLAN is composed of several standards,such as:802.11b,802.11g,802.11a,802.11n and so on. From the point of view of theantenna,802.11b/g/n occupied the frequency band of2.4GHz frequency band, while802.11a occupied5GHz frequency band. As an important part of WLAN systems,designing and producing antenna for high-performance WLAN devices is veryimportant. Work in this paper includes two aspects:Firstly, a compact planar J-pole antenna applied to WLAN routers and accesspoints(AP) is presented in this paper. The proposed antenna adopts the planar J-shapedstructure, which comprises of a meander radiator and a matching stub. The size can bereduced by using the meander structure of the radiator and the impedance matching canbe obtained by adjusting the feed point position on matching stub. The proposedantenna is realized by using a planar structure, which makes it suitable for aestheticdesign. A prototype of the antenna is constructed and tested. The experimental resultsshow that the antenna has good performance in its working band. The impedancebandwidth (|S11|<-10dB) is130MHz (centered at2.48GHz), and the radiation patternsare almost omni-directional in the H plane and bidirectional in the E plane.We also proposed the design of dual-polarized antenna for the WLAN routers. Theantenna adopts planar structure. The antenna consists of a J-pole antenna and a dipoleantenna and it is fed by the coaxial cable. When the antenna is placed perpendicular tothe ground, the J-pole antenna polarization is vertical polarization, the polarization ofthe dipole antenna is horizontal polarization. Therefore, the antenna can achievepolarization diversity. The arms of dipole antenna adopt a bent structure, so the antennasize has decreased. The section which consists of the matching stub and the feed pointplays a role of the equivalent parallel inductance. By adjusting the feed position, theantenna impedance can be changed. Therefore, the antenna itself has a matchingfunction. Simulation and experimental results show the antenna has good performanceat the working band.