Research On Pattern Reconfigurable Antenna

With the development of wireless communication technologies,reconfigurable antenna became the research focus of experts both at home and abroad,it can provides diversity functions for antenna through reconfiguring its operating frequency,polarization,or radiation pattern.Recently,the radiation pattern reconfigurable antenna has attracted the attention of many researchers,because the pattern reconfigurable antenna can be applied in noisy environments,maneuver to avoid electromagnetic interference,enhance reliability and security of system,save energy,and possess wide cover range in the wireless communication system.The pattern reconfigurable antenna can change its radiation pattern mainly by changing the antenna surface current distribution.The classical reconfigurable technologies include using mechanical moving components,loading electrical switches or electrical loads,loading electrically tunable materials,loading frequency selection surfaces(FSS),and so on.In this paper,three kinds of pattern reconfigurable antenna were designed by the classification based on the loading position.Firstly,a 2.45GHz-2.75 GHz electrically tunable pattern reconfigurable antenna was designed.The structure of the whole antenna is a printed dipole antenna loaded with electromagnetic band gap structure.The electric switch is loaded on the surface of the electromagnetic band gap structure,so as to minimize the influence of the current distribution of the driven antenna.When the switches turn on or off,electromagnetic band gap structure shows different working states in different regions,which are the state of electromagnetic band gap structure and the state of Yagi antenna reflector.Through switching the electric switch,the antenna can realize three different directions in the main beam,which covers 180 degrees.Secondly,a pattern reconfigurable antenna based on Butler matrix was proposed.A miniature Butler matrix by the application of low temperature co-fired ceramic technology was designed to face the size challenge.Then use it as a feed network for a 1 x 4 microstrip antenna array,so as to realize the pattern reconfigurable antenna.The Butler matrix has a compact and symmetrical structure,with a broad bandwidth which is more than 200 MHz.Four output ports have the phase difference of 45°,-135°,135°,-45° when the signal is input from different input ports.Finally,based on the principle of beam-width reconfiguration using FSS,a pattern reconfigurable antenna working on 3.6GHz was designed.The FSS cell consists of two layers,which loaded with PIN diode,respectively.By adjusting the state of the PIN diode,the cell can produce two working modes,which are transmission mode and the absorption mode,respectively.By switching the working mode,the transmission area of the FSS can be changed,thus the beam-width can be controlled.Place the FSS in front of a horn antenna,the main beam-width of antenna varies from 91.3 degrees to 58.8 degrees.