Investigation And Design On Magneto-Electric Dipole Antenna

With the rapid development of modern mobile communication such as 3G,LTE,WiFi,UWB;The research of broadband unidirectional antenna becomes popular.The antenna should be broadband,lower polarization,in the passband it also should have a stable gain and better direction,with a low cost and processing difficulty.In 2006,Professor Luk proposed a novel broadband antenna structure called magneto-electric dipole antenna.The antenna achieves an impedance matching bandwidth of 43.8%(VSWR<1.5),which has a stable radiation pattern in the operating frequency band,cross polarization is below-30 dB.In addition,nearly identical E-and H-plane patterns and a stable gain about 8.6dBi is achieved.On the base of research above,in this dissertation a kind of E-type broadband electro-magnetic dipole antenna,and a broadband magneto-electric dipole antenna,a cross dipole antenna loaded with magneto-electric dipole antenna are proposed.The innovations of this paper are listed as follows:(1)A kind of E-shaped broadband magneto-electric dipole antenna with a staircase-shaped feeding strip is presented.By using the E patch structure and the feeding strip,it can reduce the overall height of the antenna and the antenna achieves a relative bandwidth of 66.7%,the antenna has a stable broadside radiation pattern with low cross polarization and low back-lobe radiation over the operating band.(2)A kind of substrate integrated magnetic dipole antenna.With the printed circuit board technology,the antenna achieves an impedance bandwidth of 32.7 %(S11<-10dB)from 4.6 GHz to 6.4 GHz.Four layers of dielectric plates are pressed together and the metal via holes are used to act as magnetic dipole.The complementary antenna has a stable gain in the operating bandwidth,and the pattern is in good agreement with excellent electrical performance.(3)A crossed dipole antenna loaded with magneto-electric dipole to produce the wideband and wide-beam circularly polarized radiation characteristics is presented.The antenna operates in the L1 band of GPS.After that,we change the shape of dipole into progressive shape inspired by the bowtie antenna to further broaden the bandwidth.It increase the bandwidth from 37.5% up to 57.1% and it cover s the L1 band and the S band(VSWR<1.5),while the axis ratio is below 3dB.An average gain of over 9dBi and good circular polarization are achieved.