Research And Design Of WLAN Directional Pattern Reconfigurable Antenn

Pattern reconfigurable antennas have the virtues of large beam scanning range and tunable beam direction which can improve transmission efficiency of the communication system,reduce noise interference,and adapt to variational environment.An antenna with a complete ground has high directivity,narrow beam,and high gain but with narrow bandwidth and narrow beam scanning range.This thesis aims to enhance bandwidth of planar pattern reconfigurable antenna applied in Wireless Local Area Network(WLAN)system.Several planar antennas with two-dimensional beam scanning have been proposed.And a three-dimensional antenna with three-dimensional beam scanning has been designed based on the aforementioned planar antennas.The main work of this thesis is given in the following.(1)A planar pattern reconfigurable patch antenna has been designed to meet the requirements of antenna with wide bandwidth and low profile.The proposed antenna is composed of a driven patch and four parasitic patches.A slot is etched in the driven patch to obtain wide bandwidth and low profile.Four beam directions are achieved by controlling the four PIN diodes on the ground plane and change the shorting state of the parasitic patch.The antenna size is 140 mm×110 mm×1.5 mm and the measured common bandwidth is2.33-2.51 GHz covering IEEE 802.11 b/g WLAN band.The beam scanning range of the antenna in xoz plane and yoz plane covers ±15°.Compared with the existing planar pattern reconfigurable antennas,the proposed antenna has the advantages of lower profile and larger beam scanning range.(2)A three-dimensional pattern reconfigurable antenna array based on the planar pattern reconfigurable patch antennas has been designed to meet the requirements of antenna with multi-directional beam scanning and tunable beam tilt angle.The proposed antenna is composed of four antenna elements distributed at different position and a reconfigurable feed network.The pattern reconfiguration on the horizontal plane is obtained by electrically controlling the state of the PIN diodes loaded in the feeding network and choosing the excitation of each antenna element while the pattern reconfiguration on the vertical plane is obtained by electrically controlling the operating state of each antenna element.The antenna size is 140 mm×140 mm×110 mm and the measured common bandwidth is 2.39-2.49 GHz.The beam can be switched to Φ=0°,Φ=90°,Φ=180°,Φ=270° in the horizontal plane and the beam scanning range of the antenna in horizontal plane and vertical plane covers ±15°.Compared with the existing threedimensional pattern reconfigurable antenna,the proposed antenna has the advantages of simpler structure,smaller number of PIN diodes used,and larger beam scanning range.(3)A broadband planar pattern reconfigurable antenna has been designed to further improve bandwidth and beam scanning range of the low-profile pattern reconfigurable antenna.The antenna is composed of four broadband end-fire antenna elements and a reconfigurable feeding network.Four beam directions are obtained by controlling the PIN diodes loaded in the feeding network and choosing the excitation of each antenna element.The size of the antenna is 242 mm×242 mm×1.5 mm and the measured common bandwidth is 5.15-5.93 GHz covering IEEE 802.11 ac WLAN band.The proposed antenna can obtain±45° beam scan both in xoz and yoz plane.Compared with the existing planar reconfigurable antenna,the proposed antenna has the advantages of wider bandwidth,lower profile,and larger beam coverage.