Research On Application Of High Impedance Surface In Microstrip Antenna

As a novel type of artificial electromagnetic material,the highimpedance surface structure has been widely used in antenna design.Due to its unique electromagnetic characteristics,the high-impedance surface structure can be applied to improve antenna performance and structure: high gain,wide bandwidth,and low profile.A typical high-impedance surface is a two-dimensional periodic mushroom-shaped structure,which is made of metal and dielectric materials.It has characteristics of surface wave suppression and in-phase reflection within a certain frequency band.In this thesis,the improvement of traditional rectangular patch antenna radiation performance by loading high-impedance surface structures is studied,and the notch characteristics are obtained by loading high-impedance surface elements beside the broadband monopole antenna feed line.The main work can be summarized as the following two parts:(1)Design of broadband microstrip patch antenna loaded with high impedance surfaceBy loading high-impedance surface elements on both radiating sides of the rectangular patch antenna,the relative bandwidth of the antenna is 33.7%(8.1-11.47 GHz),which is an increase of 2.72 GHz wider than the traditional patch antenna.At a center frequency of 10 GHz,the gain of the antenna can reach10.2 d Bi,which is nearly 3.5 d B higher than the traditional patch antenna.(2)Design of ultra-wideband trap antenna loaded with high-impedance surface structureThree high-impedance surface structures were designed by loading beside the feed line of the broadband monopole antenna.The first type is two identical high-impedance surface elements.The antenna achieves a notch in the frequency range of 3.05 GHz to 3.85 GHz,covering the Wi MAX frequency band.The second high-impedance surface unit with Archimedes spiral slot,which reduces the total size of the element.The antenna obtains a notch in the frequency range of 3.1GHz to 3.94 GHz,covering the Wi MAX frequency band.The third high-impedance surface element also with Archimedes spiral slots.By adjusting the size of the two elements,the antenna achieves double notch at 3.3-3.8 GHz and 5.15-5.8 GHz,covering the Wi MAX band and WLAN band.