Research On Reconfigurable Antenna With Pattern And Frequency Selectivity

With the rapid development of modern science and technology,wireless communications technology is evolving toward miniaturization,intelligent and plane.Antenna has attracted wide attention as an important part of wireless communications system.Reconfigurable antenna becomes a hot topic in antenna field,due to the advantages of low profile,less mass and easy integration with other devices.This dissertation introduces the basic knowledge,research status and implementation method of reconfigurable antenna in detail.On this basis,one kind of reconfigurable antenna that can attain pattern and frequency selectivity is analyzed preliminary,and three compact frequency and beam reconfigurable antenna are designed.Among the three schemes of reconfigurable antenna,one design is a novel rectangle-shaped antenna with dual-band and four patterns reconfigurable characteristics.The main lobe of each pattern directs to one of four different directions in the plane with the elevation angle of 45 degree or 90 degree by controlling the states of one set of connections among the center patch,square loop and Quasi-Horn parasitic elements.The antenna can cover two resonant frequencies of 5.25 GHz and 2.45 GHz,respectively.The antenna can be used in Bluetooth(2.4-2.48GHz),Zigbee(2.4-2.834GHz)and WLAN(5.15-5.35GHz)and other wireless communication systems.Another design is a compact frequency and beam reconfigurable antenna with a defected ground plane.The antenna is able to achieve four frequency bands(2.33-2.4GHz,2.39-2.47 GHz,2.66-2.92 GHz,3-3.62GHz),which cover Wibro(2.3-2.39GHz)?Bluetooth(2.4-2.48GHz)?WLAN(2.4-2.48GHz)?Wimax(3.4-3.69GHz),and two radiation patterns at each operating frequency based on the activation of switches.The last one is a compact planar parasitic array antenna with reconfigurability in both frequency band and radiation pattern.By controlling the states of PIN diodes,the proposed antenna is capable of operating within 2.29-2.50 GHz,2.48-2.69 GHz,and 2.77-2.91 GHz,respectively,and steering radiation patterns in the whole azimuth plane to six different directions.The proposed reconfigurable microstrip antenna has the excellent impedance match in three operating frequency bands.Each operating state has its corresponding main radiating beam,and the measured-3dB beamwidths are about 76°,74°and 77°,and the measured main lobe gains can reach 4.3dBi,4.59 dBi,and 6.73 dBi at 2.42 GHz,2.57 GHz and 2.82 GHz,respectively.The antenna has excellent performance in reconfigurable antenna.The antennas are simulated using Ansoft HFSS13.0.The prototypes of the rectangle-shaped antenna with dual-band and four patterns reconfigurable characteristics and the planar parasitic array antenna with reconfigurability in both frequency band and radiation pattern antennas were fabricated and measured,the measured and simulated results agree well,which verify the correctness and feasibility of antenna design.