Design Of Wideband Magneto-electric Dipole Antennas

With the rapid development of the wireless communication technology,the wireless communication system has put forward higher and higher performance requirements for the antenna as its key component.In order to cover both the original operating frequency bands and 5G new frequency bands,the antenna should have a wider operating frequency band.In addition,the antenna should have a series of excellent characteristics such as low back lobe,stable gain,simple structure,high space utilization rate and good far field radiation pattern to meet the engineering demands.Therefore,the antennas with wide operating bands,stable gains and radiation patterns have become urgent research topics.The magneto-electric dipole antenna has attracted the attention of researchers since it has been proposed,because of its wide frequency band,good gains,and symmetrical far-field patterns.Based on this background,this thesis focuses on the wideband magneto-electric dipole antennas,and two novel wideband magneto-electric dipole antennas are designed and implemented.The main contributions of this thesis are summarized as follows.1.A wideband magneto-electric dipole antenna is presented.A pair of E-shaped radiating patches is used to form an electric dipole,while two folded patches,which are shorted to the ground,are used as the magneto dipole.Four inverted-L parasitic branches are introduced on four corners of the ground,producing new resonant points.The four parasitic branches along with the ground plane form a claw shaped reflector for the antenna to obtain stable directional radiation patterns.This antenna is fed by a modified feeding structure to improve the impedance matching characteristics of the antenna.Measured results show that the reflection coefficients of the proposed antenna are less than-10 d B in a relative bandwidth of 103.6%(from 1.18 to 3.72 GHz),and its average gain in the operating band is around 7.6 dBi.2.A wideband circular polarization magneto-electric dipole antenna is presented.In the proposed antenna,a pair of rotationally symmetrical rectangular patches is used as an electric dipole,and a pair of vertical short-circuit patches with the ground is act as an equivalent magnetic dipole.The 3 d B axial ratio bandwidth of the antenna is widened by adding chamfered edges and slots on the rectangular patches,and introducing ?-shaped parasitic branches which are sequentially rotated around the ground.In addition,four baffles are introduced around the ground,which cooperates with the ground to form a back cavity,improving the radiation performance of the antenna.A ?-shaped probe is used to excite the antenna.The measured results show that the reflection coefficients of the proposed antenna are less than-10 d B in a relative bandwidth of 89%(from 1.47 to 3.83 GHz),its 3 d B axial ratio(AR)bandwidth is 73%(from 1.72 to 3.7 GHz),and its average gain in the operating band is around 8.2 dBic.