Research On Planar Monopole Antenna With L-shaped Ground Plane

In modern wireless communications,antennas used in mobile terminals are gradually developing towards miniaturization and integration,and this makes higher demands on the structure and performance of the antenna.Planar monopole antennas are widely used in wireless communication systems because of their small size,wide operating frequency band,good omni-direction,simple technology of production and manufactory.However,during the research on the miniaturization of planar monopole antenna,it is found that the impedance bandwidth and radiation patterns are greatly affected by the size of the ground plane.Therefore,it is necessary to make research on the structure of the ground plane and bring forward new-type ground plane structures.On the basis of existing research results,planar monopole antennas with L-shaped ground plane have been intensively studied in this thesis.Several planar monopole antennas with L-shaped ground plane,which have small effective size and weak ground plane influence,have been proposed.Some of the antennas proposed in this thesis are practically manufactured and tested.The test results are in accordance with the simulation results.This illustrates that the planar monopole antenna with L-shaped ground plane proposed in this thesis can both ensure the operation bandwidth and reduce the influence of the ground plane effectively.So,such antennas have good research prospect and high application value.The main work and creative parts of this thesis are summarized as follows:1.The research status on planar monopole antenna at home and abroad is summarized.The basic principle of planar monopole antenna is introduced and the estimation method of lower resonance point is discussed.2.Several planar monopole antennas with L-shaped ground plane and circular patch are proposed.These antennas have small effective size, wide frequency band and weak influence of ground plane.The cases of common microstrip-fed,tapered microstrip-fed,bended microstrip-fed are analyzed and compared.The influences of SMA connector,ground plane size and corner cut size on return loss,impedance characteristic and radiation pattern are studied.Experiments are carried out,and the test results are in accordance with the simulation results. 3.A planar monopole antenna with L-shaped ground plane and rectangular patch is proposed.By adopting the method of cutting a slit in the ground, the current is concentrated on the radiation patch and edge of the ground plane around it,this method ensures the wide frequency band and reduces the influence of the ground plane at the same time.Experiments are carried out,and the test results are in accordance with the simulation results.