Research On WLAN Dual-Band And Dual-Polarized Beam-Reconfigurable Antenna

Nowadays,WLAN is widely used in homes,enterprises,campuses and other places with its advantages of broadband and low price.The rapid growth of wireless data traffic puts higher demands on WLAN antennas.Aiming at the problems of limited electromagnetic signal coverage,obstructions and limited system capacity in the current wireless local area network system,this paper has carried out research and design on the WLAN dual-band dual-polarized beam reconfigurable antenna.The main work and innovations of this article are as follows:1.A design scheme of a reconfigurable antenna with dual-polarized beams in the 2.4GHz frequency band of WLAN is proposed.The entire antenna adopts a dual-polarized superposition scheme:(1)The horizontally polarized antenna adopts the Alford loop antenna as the main radiating unit,and there is a gap every 90° on the circular ground.A diode is connected across each gap,and the current distribution on the circular ground can be changed by controlling the on and off of the diode,thereby controlling the deflection of the directional beam of the horizontally polarized antenna.In this way,the horizontally polarized antenna can switch between the omnidirectional beam and four directional beams in the horizontal plane.(2)The vertically polarized antenna uses an inverted triangular monopole as the main radiating unit,and a rectangular metal strip as a reflector.The deflection of the directional beam is achieved by controlling the on and off of the diode on the reflector.Finally,the vertically polarized antenna can switch between the omnidirectional beam and the eight directional beams.The main beam gain peak of the final antenna directional beam is greater than 3 d Bi,which can cover all positions in the circumferential direction.2.A WLAN 5 GHz band dual-polarized beam reconfigurable antenna design scheme is proposed.The entire antenna consists of two parts: a horizontally polarized antenna and a vertically polarized antenna.(1)The horizontally polarized antenna adopts a circular ground,an Alford loop antenna is used as the main radiating unit,and four arc-shaped microstrip lines are used as reflectors.The center of the reflector is connected by a diode,and the electrical size of the reflector is changed by controlling the on and off of the diode,thereby controlling the deflection of the directional beam.In this way,the horizontally polarized antenna can generate an omnidirectional beam and four directional beams in the circumferential direction.(2)The vertically polarized antenna uses an elliptical monopole fed by a coplanar waveguide as the main radiating unit,and a rectangular metal strip as a reflector.The deflection of the directional beam is achieved by controlling the on and off of the diode on the reflector.In this way,the vertically polarized antenna can switch between an omnidirectional beam and eight directional beams.Finally,the peak gain of the main beam of directional beams is greater than 3 d Bi and can cover all positions in the circumferential direction.3.A method for enhancing the isolation between the horizontally polarized antenna and the vertically polarized antenna is proposed.A fan-shaped metal isolation layer with etched gaps of a specific shape is designed,and finally the isolation between the 2.4 GHz horizontally polarized antenna and the vertically polarized antenna can reach more than20 d B.A higher degree of isolation is achieved when the antenna spacing is small.4.A method to suppress the secondary radiation of the surface current of the coaxial cable is proposed.The choke structure is designed by etching different numbers and different sizes of inverted L-shaped gaps on the rectangular metal plate.The radiation generated by the choke plate offsets the radiation from the surface current of the coaxial cable,effectively reduce the interference of the feed cable of the horizontally polarized antenna to the vertically polarized antenna beams.