Wideband High-Gain Antennas Loaded With Planar Parasitic Arrays

Antennas with wide impedance matching bandwidth and high-gain are highly required with the continuous advancement of modern wireless communication systems.In an antenna array with enough antenna units,a complex feeding network is indispensable,and the poor efficiency caused by the complex feeding network can not be ignored even though the antenna array can obtain the performance of high gain.Therefore,the wideband high-gain antenna which does not need a complex feeding network is considered as an excellent candidate by the antenna engineer.On the basis of the demand of wireless communication systems for wideband high-gain antenna,this dissertation is mainly concerned with the high-gain antenna loaded with planar parasitic array.1.High-gain antenna loaded with planar parasitic structure.The number of directors have substantial influence to the gain of antenna,and we also investigate the differences on the gain and HPBW with various director arrangements.The antenna obtains a 38.8% impedance bandwidth with a peak gain of 11.42 d Bi when there is 3 ? 3 parasitic units in the antenna,and the gain of the antenna is higher than 9.2d Bi in the whole operating band.When we put 4 ? 4 parasitic direction units in the high-gain antenna,which can obtain a 37.3% impedance bandwidth with a peak gain of 12.02 d Bi,and in the whole operating band,the gain is higher than 9.5d Bi.2.Resonator antenna loaded with capacitive parasitic array.A single-layer planar parasitic array structure is presented to design single-feed resonator antennas with a wide gain bandwidth and a compact size.The design of the planar parasitic array structure applied in this antenna is based on the theory of tightly coupled antenna arrays,in our work,a novel PRS structure is presented,which is constructed by two same triangular metal patches with overlapped section printed on the opposite sides of a 1-mm-thick dielectric substrate.Owing to the strong mutual coupling between the overlapped patches,the proposed antenna obtains a wider bandwidth and the size of the planar parasitic array structure can reduced by 27%.Experimental results show that the antenna obtains a 32% 3-d B gain bandwidth from 8.8GHz to 12.2GHz,with a peak gain of 13.5d Bi.Moreover,the relative impendence bandwidth is 40.9% for the voltage standing wave ratio(VSWR)less than 2 from 8.45 GHz to 12.8GHz.Compared with the feed antenna,the gain of the wideband FPRA enhances about 7d Bi.